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Canon FACSIMILE BASIC 2000 Service Manual

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FACSIMILE
FACSIMILE
BASIC
2000
REVISION 0
HY8-53A2-00Z
APR.2000
COPYRIGHT © 2000 CANON INC.
FACSIMILE BASIC2000 APR.2000 PRINTED IN JAPAN (IMPRIME AU JAPON)

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Summary of Contents for Canon FACSIMILE BASIC 2000

  • Page 1 FACSIMILE FACSIMILE BASIC 2000 REVISION 0 HY8-53A2-00Z APR.2000 COPYRIGHT © 2000 CANON INC. FACSIMILE BASIC2000 APR.2000 PRINTED IN JAPAN (IMPRIME AU JAPON)
  • Page 2 Application This manual has been issued by Canon Inc. to provide information necessary to self-study to tech- nicians who service facsimile products. This manual covers all localities where the facsimile products are sold. For this reason, there may be information in this manual that does not apply to your locality.

  • Page 3: Preface

    PREFACE This manual describes the general technology and principles of CANON facsimile operation so that those studying facsimiles for the first time and those already servicing facsimiles can gain a further understanding of these equipment. Chapters 1 and 2 describe an overview of telephony and facsimile operation. Chapter 3 onwards describes the reading section, recording section, communications and electrics in more detail.

  • Page 4: Table Of Contents

    CONTENTS PREFACE..................i CONTENTS..................ii CHAPTER 1 BASIC OF TELEPHONE INTRODUCTION TO THE TELEPHONE ........1-2 Parts of the Telephone..............1-2 Making a Call ................1-3 How do you make a call?............1-4 Voice Frequencies Carried by the Telephone......1-4 STRUCTURE OF A TELEPHONE ..........1-5 Transmitter (Microphone)............1-6 Receiver (Speaker) ..............1-7 Voice Circuit................1-7...
  • Page 5 Telephone Lines ...............2-3 Types of ITU-T Recommendations...........2-4 How Images are Transmitted ...........2-8 STRUCTURE OF A FACSIMILE..........2-13 Reading Section ..............2-15 Recording Section ..............2-18 MODEM ..................2-21 NCU board (Network Control Unit board) .......2-22 System Control Section ............2-22 THE FUTURE OF FACSIMILES ..........2-23 Color Facsimiles ..............2-23 LAN-networked Facsimiles .............2-23 Internet Facsimiles ..............2-24...
  • Page 6 Printing by LASER ..............4-24 Flow of Printing ...............4-26 Video Control Section/Printer Engine Control Section....4-27 LASER/Scanner Section............4-32 Printing Process..............4-34 Toner Cartridge...............4-46 BJ (Bubble Jet) Printer............4-48 Printing by Bubbles ..............4-48 Printing Section...............4-50 Carriage Section ..............4-51 Purge Unit ................4-56 BJ Cartridge ................4-58 CHAPTER 5 G3 FACSIMILE COMMUNICATIONS INTRODUCTION ................5-2 WHAT IS A “G3 FACSIMILE?”...
  • Page 7 Option Signals ..............5-106 Structure of Binary Signals ...........5-107 Example of G3 Procedures ..........5-122 ECM Communications ............5-123 CHAPTER 6 FACSIMILE SYSTEM INTRODUCTION................6-2 SCNT BOARD................6-3 System Control Section ............6-3 Communications Control Section ..........6-4 Reading Control Section............6-4 Printer Control Section .............6-4 NCU BOARD................6-5 Off-hook Detection..............6-6 Formation of DC Loop ..............6-6 Detection of Calling Identification (CI) ........6-9...
  • Page 8 Factors of Telephone Line Deterioration........A-6 FACSIMILE COMMUNICATION NETWORK SERVICES & MINIFAX (JAPAN ONLY) ............A-10 F-NET ..................A-12 Minifax I (MF-I)............... A-16 Minifax II (MF-II)..............A-17 TELEPHONE LINE BAND & SIGNAL SPECTRUM ....A-19 S/N..................... A-20 POLARITY INVERSION ON EXCHANGE ........ A-21 FACTORS WHICH CAUSE DETERIORATION IN QUALITY OF FACSIMILE TRANSMISSION ......
  • Page 9 CHAPTER BASIC OF TELEPHONE 1. INTRODUCTION TO THE TELEPHONE ......... 1-2 Parts of the Telephone ............ 1-2 Making a Call ..............1-3 How do you make a call? ..........1-4 Voice Frequencies Carried by the Telephone....1-4 2. STRUCTURE OF A TELEPHONE ........... 1-5 Transmitter (Microphone) ..........

  • Page 10: Chapter 1 Basic Of Telephone

    BASIC OF TELEPHONE 1. INTRODUCTION TO THE TELEPHONE You can’t transmit a document unless your facsimile and the receiving fac- simile are connected over a telephone line. In this section, let’s learn about the basics of telephones and telephone lines. Parts of the Telephone Very few people know the names of the parts of a telephone even though they use it every day.

  • Page 11: Making A Call

    BASIC OF TELEPHONE Making a Call There are names for the party being called and the party making the call. When we make a call, one of the two parties must first dial to call up the other party by the bell on its telephone. Making a call in this way, that is, dialing is called the “outgoing call”, and the call that arrives is called the “incoming call”.

  • Page 12: How Do You Make A Call

    BASIC OF TELEPHONE How do you make a call? When you call someone, you must take various actions. Let’s consider each individual action needed for making a call. (1) You pick up the handset. This means you are making a calling request. The telephone exchange gets ready to connect you to your party.

  • Page 13: Structure Of A Telephone

    BASIC OF TELEPHONE 2. STRUCTURE OF A TELEPHONE A telephone consists of a receiver (speaker), a transmitter (microphone), a voice circuit, a dial, a bell (speaker), and a hook button. Of these parts, the parts that play the most important roles are the transmit- ter and the receiver.

  • Page 14: Transmitter (Microphone)

    BASIC OF TELEPHONE Transmitter (Microphone) The voice vibrates a diaphragm compressing/releasing carbon powder. When carbon powder is compressed, its contact resistance decreases. When the powder is released, its contact resistance increases. So direct current varies corresponding to the change of pressure (voice). This is called “voice current”.

  • Page 15: Receiver (Speaker)

    BASIC OF TELEPHONE Receiver (Speaker) The receiver acts just like an electromagnet. The receiver creates voice waves by changing magnetic force, which move a vibrating diaphragm according to the current strength. Armature Diaphragm Permanent magnet Fig. 1-7 Receiver Voice Circuit When the transmitter and receiver are connected as shown in the Fig.

  • Page 16: Hook Button

    BASIC OF TELEPHONE Hook Button When a hook button is closed by picking up a handset, direct current flows to the telephone circuits. Hook button Hook button Fig. 1-9 Hook Button The purpose of this is twofold (i) so that direct current is made to flow to the transmitter to provide current for sending voice when the handset is picked up, and (ii) so that the exchange detects this direct current to recog- nize that the handset has been picked up.

  • Page 17: Dial

    BASIC OF TELEPHONE Dial Dialling enables an exchange to connect one party to a requested number according to a dialing signal. “DP” means the Dial pulse contact. The con- tact is usually closed. When you turn a dial and release it, the contact opens the same number of times as the number you dialed.

  • Page 18: Bell (Speaker)

    BASIC OF TELEPHONE Here, we have described an example (number of dial pulses = N) where the number of dial pulses is the same as the dialed number (N). However, in some countries, the number of dial pulses is sometimes different as fol- lows: The number of dial pulses is the dialed number (N) + 1 Dialed number...

  • Page 19: Types Of Telephones

    BASIC OF TELEPHONE 3. TYPES OF TELEPHONES There are three types of telephone: dial telephones and pushbutton tele- phones that are used on analog lines, and digital telephones that are used on digital lines. In this section, let’s learn about these types of telephones. Dial Telephones The type of telephone having a dial as explained earlier in section 2.5 is a dial telephone.

  • Page 20: Digital Telephones

    BASIC OF TELEPHONE Some pushbutton telephones have a dial selector switch for selecting between tone dialing (PB) and pulse dialing. With these pushbutton tele- phones, if the selector switch is set to pulse dialing, the telephone outputs dial pulses even though the telephone looks like a pushbutton telephone. Digital Telephones Though digital telephones also have 12 buttons just like a pushbutton tele- phone, the dialing signals are output not as a tone (frequency) but as a code...

  • Page 21: Circuit Diagram In The Telephone

    BASIC OF TELEPHONE 4. CIRCUIT DIAGRAM IN THE TELE- PHONE In this section, let’s learn about the basic circuits inside a telephone. Dial Telephones The Fig. 1-13 shows the basic circuit of a dial telephone. T: Transmitter R: Receiver DP: Dial pulse contact HS: Hook switch Fig.

  • Page 22: Pushbutton Telephone

    BASIC OF TELEPHONE Pushbutton Telephone The Fig. 1-15 shows the basic circuit of a pushbutton telephone. Basically, the only difference between the circuit of a pushbutton tele- phone and the circuit of a dial telephone is that the dialing signal generator differs.

  • Page 23: Introduction To The Telephone Network

    BASIC OF TELEPHONE 5. INTRODUCTION TO THE TELEPHONE NETWORK We can talk to people over a long distance because we have an interlinked telephone network which contains many telephone centers. In this section, let’s learn about the mechanism of a telephone network. Parts of a Telephone Network To communicate over a telephone line, you need two telephones, a tele- phone line, and an exchange system.
  • Page 24 BASIC OF TELEPHONE To simply connect two telephones without using an exchange, every tele- phone must be connected individually to every other telephone. This type of network is called a mesh network. Fig. 1-17 Mesh Network In a mesh network, you need more telephone lines than telephones. The number of lines needed to connect telephone is given by n(n-1)/2.
  • Page 25 BASIC OF TELEPHONE So far, we have the mesh network and the star network. These are the basic types of network systems. If we combine both networks into one system, we have a hybrid network. Fig. 1-19 Hybrid Network ït çi 1–17...
  • Page 26 BASIC OF TELEPHONE In this way, a telephone network consists of telephones used as a terminal for converting voice to electrical signals and electrical signal back again to voice, a telephone line for transmitting electrical signals to places far away, and an exchange system for connecting two telephones.

  • Page 27: Basic Structure Of A Telephone Network System

    BASIC OF TELEPHONE Basic Structure of a Telephone Network System As the number of telephones to be connected to the exchange increases and the conversation area expands, it becomes more economic to set up two or more exchanges and connect between exchanges by telephone lines rather than terminating all of the telephone lines in a single exchange.

  • Page 28: Nationwide Telephone Network (In Case Of Japan)

    BASIC OF TELEPHONE As the transit exchange relay-switches conversations between subscriber exchange, we can consider transit exchange to be ranked (classified) higher than the subscriber exchange. The rank for an exchange is called the grade, and the telephone center is called the center grade. That is, the high grade exchanges can route calls to a wider area.
  • Page 29 BASIC OF TELEPHONE A call made between subscriber areas is called a long-distance call, and can be made by dialing an area code, an exchange number, and a sub- scriber number. Long-distance call Subscriber Subscriber exchange exchange Subscriber area A Subscriber area B Fig.
  • Page 30 BASIC OF TELEPHONE • District center (DC) DCs have been established in every seat of prefectural government of the same rank city. • Toll center (TC) TCs have been established at central towns in a district center area. • End office (EO) An end office (EO) is an office that connects telephones in a subscriber area.
  • Page 31 BASIC OF TELEPHONE The big cities have a transit exchange (a local tandem exchange office) in a star network. Generally, a hybrid network is formed when many calls con- centrate on certain lines. Subscriber area We are multiple offices. Transit exchange Fig.
  • Page 32 BASIC OF TELEPHONE 5.3.2 Toll network The toll network is formed by three classes of star networks connected with upper centers and lower centers. The topmost centers form a mesh network. The nationwide toll network hierarchy of toll networks is called the toll band system.

  • Page 33: Telephone Exchanges

    BASIC OF TELEPHONE 6. TELEPHONE EXCHANGES The exchange system and the telephone network have made simultaneous progress. At first, people used the manual exchange, but now the automatic exchange has replaced the manual exchange in most offices. In this sec- tion, let’s learn about the types of telephone exchange and how they work.

  • Page 34: The Exchange

    BASIC OF TELEPHONE (3) Electronic exchange (D type) • This has the same function as crossbar’s. Moreover, the electronic exchange uses a computer as its control unit and provides high reli- ability. The Exchange An exchange is a device, so it cannot talk or listen like a human being. For this reason, the telephone sends signals that the exchange can understand, and the exchange sends signs to the telephone that a human being can understand.
  • Page 35 BASIC OF TELEPHONE 6.2.1 Details of signals and signs sent from the telephone to the exchange (1) DC loop This is for notifying the exchange that a person has picked up the handset. A DC loop has the following meaning: •...
  • Page 36 Notes 1–28...
  • Page 37 CHAPTER GENERAL DESCRIPTION OF A FACSIMILE 1. WHAT IS A “FACSIMILE?” ............2-2 Established Rules of Communication......2-2 Control Procedure ............2-2 Facsimile Groups ............2-3 Telephone Lines .............. 2-3 Types of ITU-T Recommendations........2-4 How Images are Transmitted........... 2-8 2.

  • Page 38: Chapter 2 General Description Of A Facsimile

    GENERAL DESCRIPTION OF A FACSIMILE 1. WHAT IS A “FACSIMILE?” A facsimile is a machine that is connected to the telephone line instead of the telephone, and transmits and receives documents instead of holding conversations. In this section, let’s start with a description of the rules governing facsimi- les.

  • Page 39: Facsimile Groups

    GENERAL DESCRIPTION OF A FACSIMILE Facsimile Groups ITU-T recommendations classify facsimiles into groups called “G3” and “G4.” G3 facsimiles enable the transmission of A4-size type docu- ments in about one minute on a public telephone network. G4 facsimiles, as a general rule, enable the error-free reception of documents on a public digital line.

  • Page 40: Types Of Itu-T Recommendations

    GENERAL DESCRIPTION OF A FACSIMILE Analog Line Exchange Telephone, Telephone, G3 facsimile, etc. G3 facsimile, etc. Digital Line Exchange G4 facsimile, G4 facsimile, digital telephone, digital telephone, etc. etc. Fig. 2-1 Analog Line and Digital Line In Japan, there are lines exclusively for facsimile communications called Facsimile communication network services.
  • Page 41 GENERAL DESCRIPTION OF A FACSIMILE • T.4 (Standardization of Group 3 facsimile terminals for document transmission) • Scanning track • Dimensions of terminals • Transmission time per total coded scan line • Coding scheme • T.6 (Facsimile coding schemes and coding control functions for group 4 facsimile apparatus) •...
  • Page 42 GENERAL DESCRIPTION OF A FACSIMILE • V.34 (A modem operating at data signalling rates of up to 33600 bit/ s for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits) • Conditions of transmission equipment relating to the transmission of group 3 proceudre signals (600 bps, 1200 bps, 2400 bps) •...
  • Page 43 GENERAL DESCRIPTION OF A FACSIMILE • T.433 (Document Transfer And Manipulation (DTAM) -Services and protocols-Protocol specification) • T.503 (A document application profile for the interchange of Group 4 facsimile documents) • Clarification of formats to be applied to group 4 facsimile document interchange •...

  • Page 44: How Images Are Transmitted

    GENERAL DESCRIPTION OF A FACSIMILE How Images are Transmitted The sender facsimile transmits the image over the telephone line, and the receiver facsimile receives and prints out the transmitted image. The figures below illustrate how images are sent. 2. Division into 3.
  • Page 45 GENERAL DESCRIPTION OF A FACSIMILE (1) Image This is the original image before it is transmit. Fig. 2-3 Image (2) Division into pixels The image is divided into either white or black pixels. ït çi Fig. 2-4 Division of Image into pixels 2–9...
  • Page 46 GENERAL DESCRIPTION OF A FACSIMILE (3) Conversion into electrical signals Black pixels are converted into High level signals, and white pixels are converted into Low level signals. High level signal Low level signal Fig. 2-5 Conversion into Electrical Signals (4) Modulation The picture signals are modulated.
  • Page 47 GENERAL DESCRIPTION OF A FACSIMILE (5) Transmission/Reception Image signals are transmitted in the order of lines a, b through h. Transmission Reception Fig. 2-7 Transmission/Reception (6) Demodulation Image signals a through h are sequentially demodulated into the electrical signals that represent black and white pixels. ït çi Fig.
  • Page 48 GENERAL DESCRIPTION OF A FACSIMILE (7) Reassembly of pixels Demodulated electrical signals are sequentially reassembled. Fig. 2-9 Reassembly of pixels (8) Reproduction of image The black and white image information is printed on recording paper according to the electrical signals to reproduce a copy of the original pic- ture.

  • Page 49: Structure Of A Facsimile

    GENERAL DESCRIPTION OF A FACSIMILE 2. STRUCTURE OF A FACSIMILE Now, let’s take a look at the actual structure of a facsimile. Simply speaking, we could say that a facsimile is structured by integrating a scanner (reading section) and printer (recording section) in a telephone, and providing it with a communications function (modem) for handling data exchange transactions with the other party via a telephone line(NCU board).
  • Page 50 GENERAL DESCRIPTION OF A FACSIMILE Operation Reading unit section Telephone board line System Modem control unit AC power supply Power Recording Sensors supply unit section Fig. 2-12 Block Diagram of Facsimile Electric System The facsimile has a system control section comprising mainly a CPU, and the reading section, recording section, modem and other mechanisms are connected to its periphery.

  • Page 51: Reading Section

    GENERAL DESCRIPTION OF A FACSIMILE Reading Section The role of the reading section is to read the document(s) to be transmitted to the other party and convert images into electrical signals. For those used to operating a personal computer, calling the reading sec- tion an “image scanner”...
  • Page 52 GENERAL DESCRIPTION OF A FACSIMILE 2.1.2 Flat-bed scanning By this scanning method, a photosensor comprising linearly arranged sen- sors is moved in the vertical scanning direction to read the document or the document itself is moved while being scanned by the photosensor. By this method, the required number of photosensors for reading a single line in the vertical scanning direction is moved to read a single line of the document, and the reading position is moved one line at a time in the...
  • Page 53 GENERAL DESCRIPTION OF A FACSIMILE (2) Contact sensor system Though contact sensors are inferior to CCD image sensors in terms of reading speed, contact sensor systems have the advantage that they can be downsized. This system is used on small-, medium- and large-size machines accompanying progresses in image-processing technology.

  • Page 54: Recording Section

    GENERAL DESCRIPTION OF A FACSIMILE Recording Section This is the so-called printer. Here, picture data that is sent from the other party is printed on paper. Generally, the following three methods are used for recording on a facsim- ile. 2.2.1 Thermal recording method This recording method uses paper (heat-sensitive paper) that has been coated with a color-forming layer.
  • Page 55 GENERAL DESCRIPTION OF A FACSIMILE 2.2.2 Ink jet recording method By this method, particles of ink are dispensed from nozzles to adhere to the recording paper. As plain paper is used as the recording paper, this method has the advan- tage that recording paper that has been received can be written and stamped on.
  • Page 56 GENERAL DESCRIPTION OF A FACSIMILE 2.2.3 Electrophotographic method Canon is putting onto the market facsimiles that use a LASER beam printer (LBP) engine. By this method, the pattern to be recorded is exposed on the surface of a photosensitive drum by a LASER beam, and toner is made to adhere on that pattern.

  • Page 57: Modem

    GENERAL DESCRIPTION OF A FACSIMILE MODEM Facsimiles must transmit image signals (digital signals) of scanned docu- ments to other parties via telephone lines (analog lines). For this reason, the transmitting facsimile must convert these digital signals to analog sig- nals and transmit them out onto the telephone line. This conversion is called “modulation.”...

  • Page 58: Ncu Board (Network Control Unit Board)

    The role of this control section includes the control of all facsimile devices (mainly the CPU, program ROM and memory), data processing and saving of data. Generally, the system control section corresponds to the electrical circuit boards called the SCNT board or IP board mounted on Canon facsimiles. 2–22...

  • Page 59: The Future Of Facsimiles

    GENERAL DESCRIPTION OF A FACSIMILE 3. THE FUTURE OF FACSIMILES The facsimiles we have discussed so far only transmit and receive black- and-white images over telephone lines. How will facsimiles look in the future? This section describes color facsimiles, LAN-networked facsimiles and Internet facsimiles whose use is expected to expand in the future.

  • Page 60: Internet Facsimiles

    GENERAL DESCRIPTION OF A FACSIMILE you could use the facsimile from a personal computer as a network printer or as an image scanner. Such facsimiles have already started appearing on the market. Server LAN-FAX Exchange Fig. 2-21 LAN-networked Facsimiles Internet Facsimiles The mere mention of the Internet makes people think of e-mail and home pages.
  • Page 61 GENERAL DESCRIPTION OF A FACSIMILE Either way, we believe that facsimiles will be transformed from being stan- dalone facsimile machines, and will enter the market as facsimiles to be connected to LANs and the Internet, as facsimiles for connection to net- work systems.
  • Page 62 Notes 2–26...
  • Page 63 CHAPTER READING SECTION 1. INTRODUCTION..............3-2 2. READING METHODS.............. 3-3 Sheet Reading Method ........... 3-3 Book Reading Method............. 3-4 ADF Type ................ 3-4 3. CONTACT SENSOR .............. 3-10 Structure of Contact Sensor.......... 3-10 Features of Contact Sensor .......... 3-10 ït 4.

  • Page 64: Chapter 3 Reading Section

    READING SECTION 1. INTRODUCTION This chapter describes the reading section of the facsimile. At the reading section, a document comprising two or more sheets is fed one sheet at a time to the image sensor (e.g. contact sensor) where it is read, and the resulting image data undergoes image processing.

  • Page 65: Reading Methods

    READING SECTION 2. READING METHODS There are two types of reading methods, sheet reading method and book reading method. There are a further two types of reading methods for the sheet reading method, flat-bed type and drop-in type. Reading method Sheet reading Flat-bed type ADF type...

  • Page 66: Book Reading Method

    READING SECTION Book Reading Method Book reading is a method where the document (thick document) is placed on the copyboard glass and is read by the contact sensor. This sensor is moved backwards and forwards in the vertical scanning direction along the guide shaft by motor drive transmitted to the belt via gears.
  • Page 67 READING SECTION Upper feed roller Document edge Document sensor sensor actuator actuator White mylar sheet Separation guide Document pressure Upper eject roller plate Forwarding roller Feed roller Separation roller Eject roller Contact sensor Fig. 3-5 Flat-bed type ADF Now, let’s take a look at which operations are performed. (1) Document forwarding operation When the document is inserted in the ADF section and pushes up the actu- ator on the document sensor, the forwarding roller picks up the document...
  • Page 68 READING SECTION (2) Document separation operation After document forwarding, the document is fed out into the document feed section one sheet at a time from the bottommost sheet by the separa- tion roller and separation guide. Entry of the remaining document sheets into the document feed section is prevented by the separation guide.
  • Page 69 READING SECTION Upper feed roller Document sensor actuator Document pressure plate Document edge Separation guide sensor actuator Document Forwarding Feed roller Separation roller Fig. 3-8 Document Feed (4) Document reading operation The document is held down from above by the white mylar sheet (white reference sheet).
  • Page 70 READING SECTION the actuator on the document edge sensor drops to end monitoring of the document length. The document is then output onto the document tray by the eject rollers. Document edge sensor actuator Upper eject roller Document Document tray Feed roller Forwarding roller Eject roller...
  • Page 71 READING SECTION 2.3.2 Drop-in type With this ADF type, performance when loading documents is inconsistent due to its inclined document feed path. This sometimes results in the non- feeding of sheets when a document comprising many sheets is loaded. Also, as the document output direction is downwards, output documents tend to stack poorly.

  • Page 72: Contact Sensor

    READING SECTION 3. CONTACT SENSOR Structure of Contact Sensor The structure of the contact sensor is designed to prevent dirt and dust from collecting on the sensor surface or entering the inside. The inside of the contact sensor comprises an LED array, contact glass, rod lens array and photo-transistor array.
  • Page 73 READING SECTION • When the document rises up even slightly from the glass surface, that section is read as black. So, the document must be held down by a roller. • As the document is pressed against the glass surface, there is the possi- bility that documents that tend to stick such as photographs cannot be fed.
  • Page 74 READING SECTION 3.2.1 Multi-chip type The radiated light emitted from the LED array is reflected by the docu- ment, and passes through the rod lens array to be received by the photo- transistor array. Reading surface Radiated light Reflected light Document feed direction Guide mylar sheet Contact glass...
  • Page 75 READING SECTION 3.2.2 -Si type The irradiated light emitted from the LED array is reflected by the docu- ment, and is received by the photo-transistor array. Document feed direction Sensor Document Glass substrate LED array Fig. 3-15 -Si Type (cross-section view) The glass substrate has a built-in driver circuit for amplifying the output of the received light, and the output of that driver circuit is converted to serial data to be transmitted to the system controller.

  • Page 76: Image Data Processor

    READING SECTION 4. IMAGE DATA PROCESSOR After the document is read by the contact sensor, the resulting image data undergoes various image data processing at the system controller. The following shows a block diagram outlining the content of image pro- cessing.
  • Page 77 READING SECTION • Shading memory A pre-scan is performed at the start of document reading to store the read- ing brightness data for the base color of the white mylar sheet to shading memory. Then, the data stored to shading memory is compared with the reading brightness data when the document is read to generate uniform image reading brightness data.
  • Page 78 READING SECTION • GENESIS (UHQ) (GEneration of NEw Superior Imaging System (Ultra High Quality)) GENESIS (UHQ) is an image processing method that achieves high-qual- ity images for text documents by performing edge emphasis and notch pro- cessing, and high-quality images for documents containing both text and photos by performing error diffusion processing.
  • Page 79 CHAPTER RECORDING SECTION 1. INTRODUCTION..............4-2 2. IMAGE DATA PROCESSING SECTION ........4-3 Image Area Separation Processing, Smoothing Processing and Selector ....... 4-4 Reproduction Ratio Processing Section......4-8 Ink Saving/Toner Saving..........4-11 3. PAPER FEED SECTION ............4-12 Pickup Section............... 4-12 ït Feed/Eject Section ............

  • Page 80: Introduction

    RECORDING SECTION 1. INTRODUCTION This chapter describes the recording section on a facsimile. At the recording section, the image data is processed to data for printing, and then the recording paper is picked up, printed, and output. The recording section can be broadly divided into the following three sec- tions: •...

  • Page 81: Image Data Processing Section

    RECORDING SECTION 2. IMAGE DATA PROCESSING SECTION The purpose of the image data processing is to achieve better-looking prints. After the image data has undergone various image processing by the system control section, it is sent to the printing section. Image data pro- cessing is almost the same on both LBP system and BJ system facsimiles.

  • Page 82: Image Area Separation Processing, Smoothing Processing And Selector

    RECORDING SECTION Image Area Separation Processing, Smoothing Pro- cessing and Selector 2.1.1 Image area separation processing Image area separation processing section looks at the pixels around the pixel (focus pixel) that is to be smoothed, and judges whether the pixels are part of a binary image or part of an image with half-tones such as a photo.
  • Page 83 RECORDING SECTION • Number of black/white reversions The focus is applied to a certain single pixel, and the total number of black/ white reversions in a given matrix centered around that pixel is calculated. If the adjacent pixels are black and white, then it is said that black/white reversion is occurring.
  • Page 84 RECORDING SECTION 2.1.2 Smoothing processing When image data of a resolution lower than even that of the printer is printed, the oblique or curved sections of the image become jagged. The function for removing these jagged parts to smooth oblique or curved sec- tions is called “smoothing.”...
  • Page 85 RECORDING SECTION Fig. 4-6 shows the result of smoothing when a certain document is printed in each of the standard, fine, super-fine and ultra-fine modes. Low resolution Standard image Fine converted image Super-fine converted image ït High resolution Ultra-fine converted image Fig.

  • Page 86: Reproduction Ratio Processing Section

    RECORDING SECTION Reproduction Ratio Processing Section The image is then reduced by one of the Reproduction ratio shown below. After scaling, the image data is sent to the printing section. (1) Regular reproduction Size of Size of Image Recording Reproduction Data Paper The image data is reduced by a ratio of 70%.
  • Page 87 RECORDING SECTION As a result, as the printer prints one dot of the image data using 1.772 dots, this can be converted to the following integer ratio: 1:1.772 = about 9:16 So, the printer knows that nine dots of image data are to be printed using 16 dots.
  • Page 88 RECORDING SECTION sion pattern. (Black pixels are converted to white pixels.) The following shows an example of this. There are nine dots of image data of resolution 8 (dots/mm) in the horizon- tal scanning direction. : Black 8 dots/mm pixel : White pixel Fig.

  • Page 89: Ink Saving/Toner Saving

    RECORDING SECTION Ink Saving/Toner Saving This process is performed to save the amount of ink and toner that is con- sumed during printing. On BJ printers, this is called the “ink saving” func- tion, and on LBP, this is called the “toner saving” function. This function is valid when it is set on user registration switches.

  • Page 90: Paper Feed Section

    RECORDING SECTION 3. PAPER FEED SECTION Fig. 4-12 shows the general path of the recording paper. Eject roller Printing section Feed roller Feed/eject section Pickup section Separation roller Pickup roller Path of recording paper Fig. 4-12 Path of Recording Paper One sheet of recording paper is picked up at a time by the pickup roller and separation roller, and is sent to the printing section by the feed roller.
  • Page 91 RECORDING SECTION (1) Claw method The claw at the leading edge angled section of the paper cassette holds down the recording paper. When the recording paper is picked up by the pickup roller, the retention force of the claw holds down the second sheet of recording paper onwards and separates only the first sheet of recording paper.
  • Page 92 RECORDING SECTION (2) Reverse roller method The recording paper is separated by applying torque in the counterclock- wise direction (opposite to the pickup direction) to the reverse roller. • Operation before paper pickup Torque in the counterclockwise direction is applied to the separation roller, or is applied to the reverse roller via a torque limitter.
  • Page 93 RECORDING SECTION • Operation during double-feeding The reverse roller rotates in the counterclockwise direction, and the recording paper (second sheet onwards) on the reverse roller side returns in the counter-pickup direction. Only the recording paper (first sheet) on the separation roller side is fed to the printing section. 2nd sheet sheet Fig.
  • Page 94 RECORDING SECTION 3.1.2 ASF method With this method, the recording paper is loaded directly in the pickup entrance on the facsimile body. Though the number of paper sheets that can be loaded in one operation is not as much as the cassette method, a fea- ture of this method is that it allows the mechanism to be designed more compactly.

  • Page 95: Feed/Eject Section

    RECORDING SECTION Feed/Eject Section The recording paper that arrives from the pickup section is sent to the printing section by the feed roller, and is output to the recording paper out- put exit by the eject roller after it has been printed. Eject roller Printing section Feed roller...
  • Page 96 RECORDING SECTION Recording Paper Eject Methods Normally, paper is eject in order from the first sheet after a facsimile is received. However, on some types of machines, the facsimile is tempo- rarily stored to memory so that it can be output in order from the last page (print in order).

  • Page 97: Detection Of Recording Paper Jams

    RECORDING SECTION Detection of Recording Paper Jams A “recording paper jam” is a state where loaded recording paper has jammed inside the unit without being picked up, fed or ejected. Recording paper jams are detected by the ON/OFF timing of sensors that detect the presence of recording paper.
  • Page 98 RECORDING SECTION • Pickup jam This jam occurs in the following two instances: • when the pickup sensor cannot detect the leading edge of the recording paper within a specified period of time after the pickup operation has started • when the sensor cannot detect the trailing edge of the recording paper within a specified period of time after the sensor has detected the lead- ing edge of the recording paper Pickup sensor...
  • Page 99 RECORDING SECTION • Feed jam This jam occurs when the eject sensor cannot detect the leading edge of the recording paper within a specified period of time after the pickup sensor has detected the trailing edge of the recording paper. Pickup sensor Recording paper Eject sensor...
  • Page 100 RECORDING SECTION • Fixing unit wrap-around jam (only in case of LBP) This jam occurs when the eject sensor has detected a “no recording paper” state within a specified period of time after the eject sensor has detected the leading edge of the recording paper. Fixing roller Recording paper Eject sensor...
  • Page 101 RECORDING SECTION • Eject jam This jam occurs when the eject sensor cannot detect the trailing edge of the recording paper within a specified period of time after the eject sensor has detected the leading edge of the recording paper. Recording paper Eject sensor Fig.

  • Page 102: Printing Section

    RECORDING SECTION 4. PRINTING SECTION Image data is printed on recording paper that arrives from the pickup sec- tion. This section describes the printing sections of an LBP and a BJ printer. LBP (LASER Beam Printer) As its name implies, an LBP prints images using a LASER beam. This printer is quiet during printing as it does not generate the kind of impact noise that is generated on a typewriter.
  • Page 103 RECORDING SECTION Scanning direction Scanning mirror (rotating) LASER beam Fig. 4-27 LASER Printing 2 ït çi 4–25...

  • Page 104: Flow Of Printing

    RECORDING SECTION Flow of Printing Fig. 4-28 shows the general flow of printing. System control section Printer engine section Image processing section Image data Print Print instruction Video preparations Printer engine control Video signals control section section LASER drive signals LASER/scanner section LASER beam...

  • Page 105: Video Control Section/Printer Engine Control Section

    RECORDING SECTION At the LASER/scanner section, the image is drawn on the photosensitive drum by the LASER beam. The image at this stage is not yet visible to the human eye. In the printing process section, toner is attached to this invisi- ble image on the photosensitive drum to change it to a visible image, and the toner is transferred to and fixed on the recording paper, which is then eject.
  • Page 106 RECORDING SECTION 4.4.1 Main video interface signals Printer engine Video control section control section nRDY Ready signal nPRNT Print signal LASER drive signals LASER/scanner Vertical sync signal nTOP section Horizontal sync signal nVDO Video signal (image data) nRDY nPRNT nTOP nVDO Fixed period of time...
  • Page 107 RECORDING SECTION • nBD signal (Beam Detect) This is the horizontal scanning (horizontal direction) sync signal for the LASER beam, and is used for ensuring that the image printing position in the horizontal scanning direction is constant. • nVDO signal (Video) As its name implies, this is the image signal.
  • Page 108 RECORDING SECTION The LASER beam scans one line of the image at a time to form the image on the photosensitive drum. If the scanning start position in the Horizontal scanning direction is different for each line of the image during scanning, then the image will not be able to be drawn correctly on the photosensitive drum.
  • Page 109 RECORDING SECTION The nVDO signal is sent after a fixed period after this nBD signal has been sent. Accordingly, the image can be drawn correctly on the photosensitive drum as scanning always starts from the same position for each line. nBD signal nVDO signal t : Fixed period of time...

  • Page 110: Laser/Scanner Section

    RECORDING SECTION LASER/Scanner Section Fig. 4-35 shows the basic configuration of the LASER/scanner section. LASER drive signals (video signals + LASER ON signal) Cylindrical lens Collimator lens Scanning mirror (multi-plane mirror) LASER unit Scanner motor Toric lens BD mirror Condensing lens BD circuit board Reflecting mirror Photosensitive drum...
  • Page 111 RECORDING SECTION (2) Cylindrical lens This lens focuses the LASER beam on the planes of the scanning mirror. Cylindrical lens Scanning mirror LASER beam Cylindrical lens Scanning mirror LASER beam Fig. 4-37 Cylindrical Lens (3) Toric lens This lens corrects the LASER beam again so that it becomes parallel. Scanning mirror ït LASER beam...

  • Page 112: Printing Process

    RECORDING SECTION (4) Condensing lens This lens focuses the LASER beam on the photosensitive drum. Note, however, that the scanning speed at points A and B is different by simply focusing the LASER beam as can be seen in Fig. 4-39. Accordingly, a lens that has the characteristic of ensuring that the scanning speed is uniform at any point on the photosensitive drum is used as the condensing lens.
  • Page 113 RECORDING SECTION (1) Primary charging step In this step, the surface of the photosensitive drum is charged with a nega- tive electrical charge by a roller charging system. Primary charging roller (negative electrical charge) Fig. 4-41 Primary Charging Step (2) Exposure step In this step, the LASER beam draws the image (area where the charge has disappeared) on the photosensitive drum.
  • Page 114 RECORDING SECTION (4) Transfer step In this step, the toner (image) on the photosensitive drum is transferred onto the recording paper. Drum Thansfer charging roller Direction (positve electrical charge) of progression Recording paper Fig. 4-44 Transfer Step (5) Fixing step In this step, the toner transferred onto the recording paper is fused on the recording paper to form a permanent image.
  • Page 115 RECORDING SECTION Next, let’s explain each step in a little more detail. • Primary charging step bias and bias of several thousand volts is applied to the primary charging roller. As the electrical potential of the photosensitive drum is higher than that of the primary charging roller, the negative electrical charge that was generated on the primary charging roller moves to the pho- tosensitive drum.
  • Page 116 RECORDING SECTION • Exposure step A uniform negative electrical charge is on the photosensitive drum. When the LASER beam is irradiated on the photosensitive drum in this state, the negative electrical charge of the areas irradiated by the LASER beam changes state in the neutralization direction (positive direction).
  • Page 117 RECORDING SECTION • Developing step The developing cylinder comprises a magnet and sleeve. First, the toner is charged to have a negative electrical charge by the friction between with the rotating developing cylinder. The toner is then attracted by the magnet to be held in contact on the sleeve.
  • Page 118 RECORDING SECTION • Light areas on the photosensitive drum (“black” image areas) (1) Here, toner is made to cling on the light areas on the surface of the photosensitive drum. There also exists a difference between the elec- trical potential of light areas and the electrical potential of the develop- ing cylinder.
  • Page 119 RECORDING SECTION • Dark areas on the photosensitive drum (“white” image areas) (3) Here, toner cling to dark areas though in small amounts. There also exists a difference between the electrical potential of dark areas and the electrical potential of the developing cylinder. This difference is in a mutual relationship where the electrical potential of dark areas is greater than the electrical potential of the developing cylinder.
  • Page 120 RECORDING SECTION About Toner There are two types of toner, single-component toner and double-compo- nent toner. Single-component toner is used on Canon facsimiles, and com- prises mainly resin and magnetic substance. Print Density Adjustment To adjust the density of the image to be printed, change the DC bias applied to the developing cylinder.
  • Page 121 RECORDING SECTION Curvature Separation and Static Charge Eliminator As shown in Fig. 4-52, recording paper tends to be wound onto the photo- sensitive drum more easily after toner has been transferred. For this reason, the recording paper separates naturally from the photosensitive drum due to the strength of the recording paper itself as a result of the outside diam- eter of the photosensitive drum being reduced.
  • Page 122 RECORDING SECTION • Fixing step The toner that is transferred to the recording paper is turned into a perma- nent image by applying heat and pressure. This fixing method is called the “heat fixing method.” This item describes the SURF fixing method (some- times referred to as “on-demand fixing method”) that is the mainstream heat fixing method today.
  • Page 123 RECORDING SECTION Nip Width The fixing pressure roller presses the fixing roller by coil springs on the left and right. The area where the fixing press roller presses the fixing roller is called the “nip,” and the width of this nip section is called the “nip width.”...

  • Page 124: Toner Cartridge

    RECORDING SECTION Toner Cartridge Fig. 4-56 shows the structure of the toner cartridge. This toner cartridge contains the primary charging roller, photosensitive drum and developing cylinder. Primary charging roller Toner container Blade Cleaner blade Developing cylinder Waste toner container Photosensitive drum Fig.
  • Page 125 RECORDING SECTION • Magnetic sensor method A magnetic sensor is pressed against the side of the toner container in the cartridge to detect the amount of toner in the toner container. The magnetic field generated by the toner, which is a liquid, generates a voltage on the coil inside the magnetic sensor.

  • Page 126: Bj (Bubble Jet) Printer

    RECORDING SECTION BJ (Bubble Jet) Printer With a BJ printer, the ink is made to bubble to change the state of the ink and cause ink drops to be ejected to print the image by suddenly changing the state of the ink by heat generated from the heater. Printing by Bubbles The following figure shows the operating principle of BJ printing.
  • Page 127 RECORDING SECTION (1) The nozzle is charged with ink. (2) The ink on the heater surface is suddenly heated to form small bubbles when the heater is turned ON in an extremely short period. (3) The ink suddenly vaporizes for form bubbles. (4) The bubbles expand to maximum size, and an ink drop is pressed out- side the nozzle.

  • Page 128: Printing Section

    RECORDING SECTION 4.10 Printing Section The printing section is broadly divided into the following three parts: • Carriage section • Purge unit • BJ cartridge BJ cartridge Carriage section Paper feed motor Carriage ribbon cable Carriage Carriage guide shaft Carriage belt Carriage motor Purge unit Fig.

  • Page 129: Carriage Section

    RECORDING SECTION 4.11 Carriage Section The carriage section comprises the following five mechanisms: • BJ cartridge loading mechanism • Carriage drive mechanism • Print deviation compensation mechanism • Paper feed motor drive switching mechanism • Pumping operation state detection mechanism BJ cartridge loading mechanism Print deviation...
  • Page 130 RECORDING SECTION • BJ cartridge loading mechanism The BJ cartridge is fixed mechanically onto the cartridge holder. At the same time that it is fixed onto this holder, the BJ cartridge pressure con- tacts the signal contact pad of the carriage ribbon cable to form an electri- cal connection.
  • Page 131 RECORDING SECTION • Carriage drive mechanism The carriage is installed on the carriage belt, carriage guide shaft and car- riage guide rail, and moves reciprocally in the horizontal direction by power from the carriage motor. The carriage position is detected by the home position (photo-interrupter) sensor installed at the rear side of the carriage.
  • Page 132 RECORDING SECTION • Paper feed motor drive switching mechanism The recording paper is fed and cleaning performed by switching the power of he paper feed motor. (1) During recording paper feed The power in the forward direction of the paper feed motor is transmit- ted to the paper feed roller to feed the recording paper.
  • Page 133 RECORDING SECTION Home Position Sensor The maintenance jet absorber on the purge unit is the home position (car- riage reference position) of the carriage. When the carriage is not at the home position (carriage reference position), a home position error occurs. Even if image data is received during a home position error, printing is not performed, and the received image data is stored to memory.

  • Page 134: Purge Unit

    RECORDING SECTION 4.12 Purge Unit The purge unit performs cleaning operation. The purpose of cleaning is to eliminate defective printing caused by faulty ejection discharge of ink from the BJ cartridge. Cleaning involves the fol- lowing four operations: • Capping operation •...
  • Page 135 RECORDING SECTION • Capping operation This operation functions to prevent the drying of ink, ink leakage and the adhesion of dust on the BJ print head. The rubber cap on the pump rotates several tens of times by the carriage pressing the control pin when it moves to the home position, and covers the nozzle outlets on the BJ cartridge.

  • Page 136: Bj Cartridge

    RECORDING SECTION 4.13 BJ Cartridge 4.13.1 Structure of bj cartridge Fig. 4-65 shows the structure of the BJ cartridge. Cartridge cover Ink sponge Ink filter Ventilation holes Cartridge body Aluminum plate Joint pipe Signal contact pad BJ nozzle Face plate BJ print head unit Fig.
  • Page 137 RECORDING SECTION • BJ print head unit The ink that is supplied from the ink sponge is sent to the BJ nozzles according to print signals that arrive from the signal contact pad. Filament contacts Protective bond for filament contacts Printed circuit board Silicon plate Signal circuit...
  • Page 138 RECORDING SECTION There are two types of BJ cartridge: ink cartridge integrated type and ink cartridge separate type. When the latter type of BJ cartridge has run out ink, replacement of only the ink cartridge is possible. Generally, the ink cartridge is called the “ink tank.”...
  • Page 139 RECORDING SECTION 4.13.2 Types of bj cartridges The following table shows the types of BJ cartridges used on facsimile products. Ink Retention BJ Print Head/ Target Ink Type State Ink Tank Tank BC-01 black Ink sponge Integrated type — BX-2 black Ink sponge Integrated type —...
  • Page 140 RECORDING SECTION 4.13.3 Ink detection method There are two types of ink detection methods: a light-transmitting type photo-interrupter method that uses an optical sensor and a reflecting-type photo-interrupter method. A dot count method that uses software to count the number of ink ejects (dot count) is incorporated in some products. •...
  • Page 141 RECORDING SECTION • Reflecting-type photo-interrupter method At the end of printing, light is emitted from the LED (light-emitting sec- tion) in the direction of the footer mark (black) printed on the trailing edge of the recording paper, and the reflected light is detected by a photo-tran- sistor (light-receiving section).
  • Page 142 RECORDING SECTION • Reflecting-type photo-interrupter method + dot count method When the power is turned ON or at the end of printing, light is emitted from the LED (light-emitting section) in the direction of the ink tank filled with liquid ink (black), and the reflected light is detected by the photo- transistor (light-receiving section).
  • Page 143 CHAPTER G3 FACSIMILE COMMU- NICATIONS 1. INTRODUCTION..............5-2 2. WHAT IS A “G3 FACSIMILE?”..........5-2 3. G3 FACSIMILE IMAGE TRANSMISSION ........ 5-3 Structure of Image Signals..........5-3 Transmission Time ............5-5 4. CODING SCHEMES ..............5-8 Why is Coding Necessary? ..........5-8 MH Coding Scheme (One-dimensional Coding Scheme) ..

  • Page 144: Introduction

    G3 FACSIMILE COMMUNICATIONS 1. INTRODUCTION This chapter describes the fundamental technology and transmission con- trol procedures relating to G3 facsimile communications. 2. WHAT IS A “G3 FACSIMILE?” “G3 facsimile” is the general term for facsimiles made in compliance with ITU-T recommendations on an analog telephone line.

  • Page 145: G3 Facsimile Image Transmission

    G3 FACSIMILE COMMUNICATIONS 3. G3 FACSIMILE IMAGE TRANSMISSION The following shows a block diagram of G3 facsimile image transmission. Transmitting Document Contact Coding Modulation To the line side sensor conversion Receiving From the line Received side Demodu- Decoding Recording image lation section Fig.
  • Page 146 G3 FACSIMILE COMMUNICATIONS lines/mm (ultra-fine mode) depending on the product. After the image is read, coding is performed successively in the horizontal scanning direction one scanline at a time. Horizontal scanning line density 8 dots / mm 1728 dots Vertical scanning line 1145 lines density 3.85 lines / mm Horizontal scanning direction...

  • Page 147: Transmission Time

    G3 FACSIMILE COMMUNICATIONS special signal called an “EOL” for distinguishing the delimiter of each line. The start of the 1st line is also prefixed with an EOL. For this reason, each coded line is enclosed by EOLs in each scanline in the horizontal scanning direction.
  • Page 148 G3 FACSIMILE COMMUNICATIONS are mounted on a MODEM, and communications is performed using the fastest transmission speed held by the two MODEMs on the transmitting side and the receiving side. 3.2.2 Image data compression methods The image compression method is also called the “coding scheme.” When image data of the same size is compressed, the size of the data after com- pression changes depending on the coding scheme that is applied.
  • Page 149 G3 FACSIMILE COMMUNICATIONS Data Data Fill When shorter than MTT (transmission with fills) Data When equal to or longer than MTT (transmission without fills) Fig. 5-4 When Minimum Transmission Times Differ ITU-T recommendations, the standard minimum transmission time is set to 20 ms. Optional available times are 0 ms, 5 ms, 10 ms and 40 ms. A “0 ms MTT”...

  • Page 150: Coding Schemes

    G3 FACSIMILE COMMUNICATIONS 4. CODING SCHEMES Why is Coding Necessary? One of the features of a G3 facsimile is that image data is coded before it is transmit and received. The reason for coding is to reduce the size of the data to be actually transmitted to reduce the transmission time.
  • Page 151 G3 FACSIMILE COMMUNICATIONS unwanted areas exist is called “redundancy”. The larger the redundancy, the greater the effect of coding becomes. Example of document Example of completely containing characters black document Fig. 5-6 Examples of Documents with High Redundancy Let’s consider the document shown in Fig. 5-7 below. When the focus is applied to a certain scanline, it will be noted that the scanline comprises white pixel groups and black pixel groups.

  • Page 152: Mh Coding Scheme (One-Dimensional Coding Scheme)

    G3 FACSIMILE COMMUNICATIONS The Modified READ coding scheme (MR coding scheme) and the Modi- fied Modified READ scheme (MMR coding scheme) are widely used as optional coding schemes for G3 facsimiles. The JBIG (Joint Bi-level Image experts Group) coding scheme that started to gain in popularity at the same time as V.34 MODEMs has also been rec- ommended by ITU-T, and is expected to further gain in popularity.
  • Page 153 G3 FACSIMILE COMMUNICATIONS 4.2.1 Outline of MH coding scheme Codes having a fewer number of bits are allocated to codes to be swapped for black and white that appear more frequently when coding is performed. By this allocation, the data ultimately becomes compressed data, and the transmission time is reduced.
  • Page 154 G3 FACSIMILE COMMUNICATIONS (2) MH coding After being converted to run lengths, the scanlines are converted to MH codes. These MH codes comprise terminating codes and make-up codes. (See the table of page 5-14.) Different mechanisms are used for converting to MH codes for when the run length is 0 to 63, and when the run length is 64 or more.
  • Page 155 G3 FACSIMILE COMMUNICATIONS (3) Coding of one scanline Coding is completed by arranging the MH codes of each run consecutively. The code sequence for one scanline for which coding has been completed is called “data.” Total 27 bits MH-coded 1100 10100 011000 00101101...
  • Page 156 G3 FACSIMILE COMMUNICATIONS Because of coding, the size of the information increased fourfold. In other words, this kind of document can be transmitted faster without it being coded. Table 5-2 Terminating Code Table White Run Terminating Black Run Terminating Length Code Length Code...
  • Page 157 G3 FACSIMILE COMMUNICATIONS Table 5-2 Terminating Code Table White Run Terminating Black Run Terminating Length Code Length Code 00010010 000001101011 00010011 000011010010 00010100 000011010011 00010101 000011010100 00010110 000011010101 00010111 000011010110 00101000 000011010111 00101001 000001101100 00101010 000001101101 00101011 000011011010 00101100 000011011011 00101101 000001010100 00000100...
  • Page 158 G3 FACSIMILE COMMUNICATIONS Table 5-3 Make-up Code Table Make-up Code Table 1 White Run Black Run Make-up Code Make-up Code Length Length 11011 0000001111 10010 000011001000 010111 000011001001 0110111 000001011011 00110110 000000110011 00110111 000000110100 01100100 000000110101 01100101 0000001101100 01101000 0000001101101 01100111 0000001001010 011001100...

  • Page 159: Mr Coding Scheme (Two-Dimensional Coding Scheme)

    G3 FACSIMILE COMMUNICATIONS Table 5-3 Make-up Code Table Run Length (white and black) Make-up Code 2240 000000010110 2304 000000010111 2368 000000011100 2432 000000011101 2496 000000011110 2560 000000011111 MR Coding Scheme (Two-dimensional Coding Scheme) 4.3.1 Outline of MR coding scheme With G3 facsimiles, the MR coding scheme can be used as an option in addition to the MH coding scheme.
  • Page 160 G3 FACSIMILE COMMUNICATIONS Previous line Present line Fig. 5-15 Example of Two Consecutive Scanlines This scheme is particularly effective in coding documents containing lots of text broadly spread vertically or horizontally (that is, documents con- taining few shifts of changing pixels). By the MH coding scheme, 3-bit, 4-bit and at maximum 13-bit coded data must be used to express a single run length.
  • Page 161 G3 FACSIMILE COMMUNICATIONS “parameter K”. This is standardized as shown in the table below. By this measure, if, for example, a transmission error prevents data from being decoded correctly, decoding can be performed correctly from after the next MH data. The line that was coded by the MH scheme to be referenced to at this time is called the “reference line.”...
  • Page 162 G3 FACSIMILE COMMUNICATIONS 4.3.3 Structure of image signals in MR coding scheme Fig. 5-17 shows the image signals when parameter K is 2. Structure of image signals in MR coding scheme One page's worth of image signals EOL+1 Data (MH) EOL+0 Data (MR) Fill...
  • Page 163 G3 FACSIMILE COMMUNICATIONS b1: The first changing pixel on the reference line to the right of a0 and of opposite color to a0 b2: The next changing pixel to the right of b1 on the reference line Reference line Coding line Fig.
  • Page 164 G3 FACSIMILE COMMUNICATIONS Processing of First Pixel of Line The first starting pixel a0 on each coding line is imaginarily placed at a position just before the first pixel, and is regarded as a white pixel. The first run length on a line a0a1 is replaced by “a0a1-1”. In other words, if the first run is black and is considered to be coded by the horizontal mode, then the first code word M(a0a1) corresponds to a white run of zero run length.
  • Page 165 G3 FACSIMILE COMMUNICATIONS (2) Vertical mode When this mode is detected, the position of a1 is coded at a position rela- tive to the position of b1. The relative distance a1b1 can take on one of seven values V(0), VR(1), VR(2), VR(3), VL(1), VL(2) and VL(3), each of which is expressed by a separate code word.
  • Page 166 G3 FACSIMILE COMMUNICATIONS Table 5-5 MR Code Table Mode Elements To Be Coded Notation Code Word Pass b1, b2 0001 Horizontal a0 a1, a1 a2 001+ M(a0 a1)+ M(a1 a2) Vertical a1 just under b1 a1 b1 = 0 V(0) a1 b1 = 1 a1 to the right of VR(1)
  • Page 167 G3 FACSIMILE COMMUNICATIONS Start First line of K lines? EOL+0 EOL+1 Place a0 just before 1-dimensional coding the 1st pixel Detect a1 Detect b1 Detect b2 b2 to the left of |a1 b1 |<3 Pass mode coding Place a0 just Detect a2 under b2 ït...
  • Page 168 G3 FACSIMILE COMMUNICATIONS • Example of MR coding Let’s try applying MR coding to the example A4 size document shown below, assuming that the parameter K is 4. 1728 bits 1st line 2nd line 3rd line 4th line 5th line 6th line 7th line 8th line...
  • Page 169 G3 FACSIMILE COMMUNICATIONS MH coding EOL+1 1728W EOL+0 1st line 0000000000011 010011011 0011010 0000000000010 MR coding V(0) EOL+0 2nd line 0000000000010 MR coding H+M(3)+M(1) H+M(4)+M(1) H+M(3)+M(1) 001 1000 010 001 1011 010 001 1000 010 3rd line H+M(2)+M(7) V(0) EOL+0 001 0111 00011 0000000000010 MR coding...

  • Page 170: Mmr Coding Scheme

    G3 FACSIMILE COMMUNICATIONS 4.3.6 Effect of MR coding scheme The table shows the size of compressed data by the MR coding scheme and the MH coding scheme. Table 5-7 Comparison of the Effect by MR Coding and MH Coding MR coding MH coding 1st line 43 bits...

  • Page 171: Jbig Image Compression Encoding Scheme

    G3 FACSIMILE COMMUNICATIONS JBIG Image Compression Encoding Scheme 4.5.1 Outline of the JBIG image compression encoding scheme The JBIG Image Compression Encoding Scheme is recommended in ITU- T T.82/T.85 as a new bi-level (bi-level: White and Black) image compres- sion encoding scheme developed by JBIG (Joint Bi-level Image experts Group).
  • Page 172 G3 FACSIMILE COMMUNICATIONS Progressive Sequential Fig. 5-25 Images The characteristics of Progressive Bi-level Image Compression are explained below as a reference. First of all, after the original image has been read in at high resolution, it is converted to low resolution, and this low resolution image data proceeds to be encoded (compressed).
  • Page 173 G3 FACSIMILE COMMUNICATIONS 4.5.2 Single progression sequential bi-level image com- pression scheme The Single Progression Sequential Bi-level Image Compression Scheme used in this fax is explained below. The Progressive Bi-level Image Compression Scheme uses multiple reso- lution layers on a single page (multi-level layers, low resolution layers to high resolution layers) to perform encoding/decoding.
  • Page 174 G3 FACSIMILE COMMUNICATIONS 4.5.3 Encoding scheme In the JBIG encoding used in the Single Progression Sequential Bi-level Image Compression Scheme, uses in the encoder shown below to encode to the original the results of comparison of the line currently being pro- cessed and the previous line, as well as the predicted value of an image pixel (white or black) used in a model template.
  • Page 175 G3 FACSIMILE COMMUNICATIONS (1) In the pattern prediction section, the line currently being processed and the current line are compared, and judged to match or not match. A flag showing whether or not the lines match (1 bit, 0: match, 1: don’t match) is attached to the head of each line according to this judg- ment.
  • Page 176 G3 FACSIMILE COMMUNICATIONS very effective when encoding a periodic pixel, similar to a dither pattern image. The position of AT in the figure is the beginning position of the AT pixel. (3) The study table, as shown below, is constructed by all of the 10-bit pixel patterns output by the model template, and their corresponding status numbers and predicted values of the pixel to be encoded.
  • Page 177 G3 FACSIMILE COMMUNICATIONS Table 5-9 Probability Estimation Table NLPS NMPS SWITCH NLPS NMPS SWITCH 5A1Dh 01A4h 2586h 0160h 1114h 0125h 080Bh 00F6h 03D8h 00CBh 01DAh 00ABh 00E5h 008Fh 006Fh 5B12h 0036h 4D04h 0706h 50E7h 05CDh 4B85h 04DEh 5597h 040Fh 504Fh 0363h 5A10h 02D4h...
  • Page 178 G3 FACSIMILE COMMUNICATIONS Example: A brief explanation of how the study table works is given below. It is assumed that each of the model template pixels 1 to 10 in the image below are white. • In this case, the model template pixel pattern is 000h. •...
  • Page 179 G3 FACSIMILE COMMUNICATIONS The study table is constantly updated in this way, increasing the probabil- ity of accurate predictions. (4) The probability estimation table is published in the ITU-T T.82. Its contents are fixed, differing from those of the study table. This table shows probability of accuracy/inaccuracy in the form of a range, according to the accurate/inaccurate results of a given status prediction value.
  • Page 180 G3 FACSIMILE COMMUNICATIONS more detail. This operation is called “Renormalization”, and this range (A) is reset to a value above a certain range The concept of alithmetic encoding is simply explained below. The following assumptions are made in order to make the explanation easy to understand.
  • Page 181 G3 FACSIMILE COMMUNICATIONS LSZ, A2=A1-LSZ, and A3=A2-LSZ. In the case of an inaccurate prediction, range A=LSZ. *3 Actually, hexadecimal 8000. *4 Actually, the hexadecimal value will be shifted to the left two times, and thehexadecimal will be over 8000. Next, the encoding for continuos accurate predictions will be simply explained.
  • Page 182 G3 FACSIMILE COMMUNICATIONS 4.5.4 Construction of image data with JBIG image com- pression encoding Images are encoded in block units called stripes, as shown in the figure below. Document width (XD) Header Floating marker code Stripe Stripe length (L0) Floating marker code Stripe JBIG...
  • Page 183 G3 FACSIMILE COMMUNICATIONS 4.5.5 Explanation of bi-level image header section (BIH) The BIH is shown in the construction figure below. It designates the image size, number of lines per stripe, model template, etc. BIH (Bi-level Image Header) FILL Orber Option DPTABLE 1byte 1byte...
  • Page 184 G3 FACSIMILE COMMUNICATIONS Symbol Meaning Parameter Reference Indication of progressive-compatible 1 bit 0 fixed sequential coding ILEAVE Interleaved transmission order of 1 bit 0 fixed multiple bit plane SMID Transmission order of stripes 1 bit 0 fixed LRLTWO Number of reference lines 1 bit 0/1 0: 3 lines 1: 2 lines...
  • Page 185 G3 FACSIMILE COMMUNICATIONS 4.5.8 Explanation and parameters for each symbol used in (1) Floating marker code section The floating marker code is set at the head of the stripe data entity (SDE). In order to distinguish the encoding and the floating marker code, it is imperative that ESC (escape code: 0xFF) be set at the head.
  • Page 186 G3 FACSIMILE COMMUNICATIONS STUFF Image data is a variable, so STUFF:0 (zero) is adjusted by continuous sending so that the image data can be arranged into byte units or word (2 byte) units. SDNORM (Stripe data completion: 0x02) Shows the completion of stripe data 0x02 SDRST (The reset at completion of stripe data: 0x03) Shows the completion of stripe data.

  • Page 187: Modulation Method

    G3 FACSIMILE COMMUNICATIONS 5. MODULATION METHOD After the document is scanned, the resulting image data is converted to compressed digital data by coding described in the previous section. How- ever, the telephone line that is used when transmitting that digital data is for transmitting analog signals “voice,”...

  • Page 188: Shift And Modulation Methods

    G3 FACSIMILE COMMUNICATIONS In this example, the digital signals change the amplitude of the carrier wave. For this reason, this modulation method is called “amplitude shift keying modulation.” As can be seen from the figure, the digital informa- tion (0, 1) is expressed by the size of the amplitude of the analog carrier wave.

  • Page 189: Modulation Methods Up To 9600 Bps

    G3 FACSIMILE COMMUNICATIONS Modulation Methods up to 9600 bps Here, let’s describe modulation methods having a data transmission speed up to 9600 bps that is currently used on almost all facsimiles. 5.3.1 Frequency shift keying Frequency Shift Keying (FSK) is a modulation method that is widely used on facsimiles to transmit facsimile procedure signals.
  • Page 190 G3 FACSIMILE COMMUNICATIONS 5.3.2 Phase shift keying Phase Shift Keying (PSK) is a general-purpose modulation method that is used on facsimiles to transmit image signals. This system expresses digital data by changing the phase of the carrier wave. Here, let’s describe PSK by starting with a description of the meaning of “phase change.”...
  • Page 191 G3 FACSIMILE COMMUNICATIONS (1) Concept of PSK method The PSK method expresses digital information by changes in the phase of the carrier wave. The size of the change in the phase that occurs as a result of modulation differs according to the PSK method adopted. By the PSK method, information is not expressed by the actual shape of the carrier wave itself but by changes in the phase of the carrier wave.
  • Page 192 G3 FACSIMILE COMMUNICATIONS Coded image data is grouped into two consecutive digital bits, and the car- rier wave is modulated every 1/1200 seconds on each group. In other words, there are 1200 phase changes every second. Modulation speed (baud rate) = 1200 baud Transmission speed = 2400 bps Time 1/1200 sec...
  • Page 193 G3 FACSIMILE COMMUNICATIONS ”010” ”000” ”011” ”001” (Absolute phase) ”111” ”101” Tribit ”110” Phase shift (relative phase) ”100” Fig. 5-44 Spatial Diagram of 8-phase PSK Method Coded image data is grouped into three consecutive digital bits, and the carrier wave is modulated every 1/1600 seconds on each group. In other words, there are 1600 phase changes every second.
  • Page 194 G3 FACSIMILE COMMUNICATIONS 5.3.3 Quadrature amplitude modulation method Quadrature Amplitude Modulation (QAM) is a modulation method that expresses digital information using the changes in both the amplitude and phase. From this, we can understand the following: AM + PSK = QAM (1) 9600 bps QAM method This QAM method groups digital image data into 4-bit groups called “quad bits.”...
  • Page 195 G3 FACSIMILE COMMUNICATIONS Modulation speed (baud rate) = 2400 baud Transmission speed = 9600 bps Time Modulated as amplitude Modulated as phase shift 1/2400 sec Coded image data 0 0 1 0 1 1 1 0 0 0 1 1 1 0 0 1 1 1 0 1 QAM-modulated...
  • Page 196 G3 FACSIMILE COMMUNICATIONS (3) Additional explanation relating to QAM methods The purpose of QAM methods is not to increase the transmission speed by generally increasing the number of phases in modulation processing. The reason for this is that as a distortion occurs due to the characteristics of telephone line which results in the position of the modulation signal shift- ing and amplitude change.

  • Page 197: High-Speed Modems Above 14400 Bps

    G3 FACSIMILE COMMUNICATIONS Boundary Fig. 5-48 Target of QAM Method and Spatial Pattern High-speed MODEMs above 14400 bps Since 9600 bps MODEMs recommended as V.29 in 1976 were adopted in facsimiles, MODEM technology has advanced all the more to the point that facsimiles capable of transmitting and receiving at transmission speeds exceeding 9600 bps are in the process of becoming mainstream.
  • Page 198 G3 FACSIMILE COMMUNICATIONS with transmission speeds exceeding 9600 bps were developed. Due to this background, ITU-T decided in 1985 on the standardization of a 14400 bps MODEM that used a coding QAM method as a MODEM exclusively for 4-wire exclusive lines. Then in 1988, this MODEM was officially recom- mended as V.33, and facsimiles that were capable of communicating with MODEMs made by other companies and that were capable of 14400 bps communications using proprietary modes were developed as MODEMs...
  • Page 199 G3 FACSIMILE COMMUNICATIONS coded data on a convolutional coder is called the “coding constraint length,” and is two in the case of the coder in Fig. 5-49. The sum of modulo 2 is taken. Coded Shift register output data Input data The sum of modulo 2 is taken.
  • Page 200 G3 FACSIMILE COMMUNICATIONS output data at that moment in time. In addition to Fig. 5-50, this nature of a convolutional coder can also be expressed by the figure of a trellis shape in Fig. 5-51. This figure is called a trellis diagram. As the nature of convolu- tional coding is expressed by this trellis diagram, convolutional coding is generally referred to as “trellis coding.”...
  • Page 201 G3 FACSIMILE COMMUNICATIONS 010001 and each of the eight possible coded data strings of all these become that as shown in Table 5-10. In this example, there are three coded data strings (000000, 000011 and 110101) for which the Hamming dis- tance with receive data string 010001 is the minimum, and the Hamming distance is 2 in each case.
  • Page 202 G3 FACSIMILE COMMUNICATIONS Here, the survivor paths in any step i exist individually in each of the respective states, and the distances (pathmetric) with receive data strings relating to each survivor path are assumed to Mai, Mbi, Mci and Mdi. At this time, the following operation is repeated in Vitterbi decoding.
  • Page 203 G3 FACSIMILE COMMUNICATIONS Pathmetric Pathmetric Branchmetric Branchmetric Comparison Selection Storage Path update/storage Pathmetric Path memory ai+1 ai+1 Branchmetric Branchmetric Comparison Selection Storage Path update/storage Pathmetric Path memory bi+1 bi+1 Fig. 5-52 Basic Flow of ACS Operation ït This concludes a brief explanation of the principles of Vitterbi decoding. When this trellis coding/Vitterbi decoding scheme is used for voice band- width lines, generally, the branchmetric or pathmetric to the receive data çi...
  • Page 204 G3 FACSIMILE COMMUNICATIONS 5.5.2 Trellis coding/vitterbi decoding on V.17 MODEMs MODEMs support various modulation systems such as differential phase modulation and quadrature phase modulation. All of these modulation sys- tems make the digital data correspond to analog signals and transmit infor- mation.
  • Page 205 G3 FACSIMILE COMMUNICATIONS Vitterbi decoding is not in the recommendation. However, at the present moment, Vitterbi decoding is generally used as it is the most efficient decoding scheme for trellis coding. (1) 8-state trellis coding Fig. 5-53 shows the trellis coder in V.17. 2n-1 1n-1 Differential coder...
  • Page 206 G3 FACSIMILE COMMUNICATIONS Table 5-11 Differential Coding in V.17 Input Advance Input Output 1n-1 2n-1 By being coded, these 2-bit coded data Y1n and Y2n are appended a 1-bit redundant bit, and are output as 3-bit coded data Y0n, Y1n and Y2n. The 3-bit output coded data is mapped systematically on the signal spatial dia- gram as shown in Fig.
  • Page 207 G3 FACSIMILE COMMUNICATIONS Q 90 0000110 0001110 0000011 1001111 0001011 1000111 1100100 1001010 1110100 1000010 1010100 1011101 1100001 1111101 1110001 1101101 1010001 1010110 1011000 0010110 1111000 0011110 1101000 1011110 1010011 1101111 0010011 0101111 0011011 0100111 1011011 1100111 1000100 1101010 0100100 0101010 0110100 0100010 0010100 1100010 0000100 0001101 1000001 0011101 0100001 0111101 0110001 0101101 0010001 1001101 0000001...
  • Page 208 G3 FACSIMILE COMMUNICATIONS State State n+1 1, n+1 2, n+1 3, Fig. 5-55 Shift in States in 8-state Trellis Coding At time n, when W2n from among three bits W1n, W2n and W3n currently stored on the convolutional coder is 0, one of 000(=A), 010 (=B), 001(=C) or 011(=D) is output as the coded bit string, and when W2n is 1, one of 110(=E), 101 (=F), 111(=G) or 100(=H) is output.
  • Page 209 G3 FACSIMILE COMMUNICATIONS Fig. 5-56 Mapping Rules in Trellis Coding (1) ït If we focus on only expression by A to H regarding these 128 signal points, of points A to H, four respective points A, B, C and D will be çi selected under the condition Y0n=0.
  • Page 210 G3 FACSIMILE COMMUNICATIONS Fig. 5-57 Mapping Rules in Trellis Coding (2) In other words, the area of these 16 points is four times the area of the orig- inal 128 points. This means that this area has a tolerance of four times with respect to data errors caused by line noise.
  • Page 211 G3 FACSIMILE COMMUNICATIONS (2) Soft-judgment Vitterbi decoding Recommendation V.17 stipulates only 8-state trellis coding, and the fact that no stipulations whatsoever are made regarding decoding for this cod- ing scheme is as already mentioned above. For this reason, the following describes an instance where soft-judgment Vitterbi decoding is used as a decoding method for trellis coding in a V.17 MODEM described above.
  • Page 212 G3 FACSIMILE COMMUNICATIONS ably. An increase of the pathmetric to be stored means that hardware equivalent to that value will be required, and in terms of economy this can- not be said to be efficient. For this reason, the scale of the hardware can be reduced by configuring a circuit in such a way that the calculation of the pathmetric reduces fixed values at a certain point in time.
  • Page 213 G3 FACSIMILE COMMUNICATIONS 010100 010001 111110 000111 011100 011001 110110 010111 110101 110000 111011 000010 100101 100000 110011 010010 011110 100111 001100 001001 101110 001111 111100 111001 011011 100010 101101 101000 101011 001010 000101 000000 000100 000001 001110 101111 101100 101001 100110 011111 111101 111000 001011 101010 001101 001000 100011 011010 010110 110111 100100 100001...
  • Page 214 G3 FACSIMILE COMMUNICATIONS the carrier frequency of the V.32 MODEM family is the main frequency used by ATT in the United States and BT in the United Kingdom, be adopted. At the assembly, deliberation turned into an argument between US manufacturers and Japan who insisted on the different carrier fre- quency of 1700 Hz.

  • Page 215: Modem Technology

    G3 FACSIMILE COMMUNICATIONS V.34 MODEM Technology The image transmission time is reduced drastically compared with the pre- vious models by the V.34 modem (maximum transmission speed 33600 bps) recommended by ITU-T. 5.6.1 V.8/V.34 protocol (1) Outline • The V.8 protocol is used as the startup protocol to move to V.34. The V.8 protocol enables connection with fax machines, data modem and equipment using existing V-series modems.
  • Page 216 G3 FACSIMILE COMMUNICATIONS 1. The V.34 protocol uses ECM. If the ECM SW in user data is set to OFF, the V.8 protocol is not executed. Therefore, the V.34 protocol is not used, and V.17 or a lower protocol is selected. 2.
  • Page 217 G3 FACSIMILE COMMUNICATIONS (2) Typical protocol Declares the usable modulation Connected to the line mode. Network interaction Declares that V.34 capability exists ANSam (Phase 1) on each machine, and transfers the V.34 procedures with phase 2. INFO0c INFO0a After declaring the modem's modulation speed capacity, etc.
  • Page 218 G3 FACSIMILE COMMUNICATIONS • Network interaction (Phase 1) The V.8 protocol is used as the startup protocol for high-speed modem V.34. The V.8 protocol determines the best modulation scheme (V-series modem mode) that is available between the transmitter and receiver. Transmitter Abbre- Signal...
  • Page 219 G3 FACSIMILE COMMUNICATIONS Receiver Abbre- Signal Meaning Remarks viation Modified ANSam 2100-Hz tone signal Equivalent to answer tone amplitude-modulated CED for previous by 15 Hz. models. Joint menu Indicate the terminal Modulated by signal type, such as a fax V.21(H) machine, and an avail- able modulation scheme in response to...
  • Page 220 G3 FACSIMILE COMMUNICATIONS • Probing (Phase 2) The line characteristics are measured and modulation-related parameters, such as symbol rate, are set. Transmitter Abbre- Signal Meaning Remarks viation INFO INFO0c Indicate modem capa- Transmission sequence bilities, such as baud speed: 600bps rate and frequency transmission function (two frequency bands...
  • Page 221 G3 FACSIMILE COMMUNICATIONS Receiver Abbre- Signal Meaning Remarks viation INFO INFO0a Report the modem Transmission sequence capabilities, such as speed: 600bps baud rate and fre- quency transmission ability. Tone A Modem synchroniza- The phase of the tion with a 2400-Hz A- signal is Tone A tone signal.
  • Page 222 G3 FACSIMILE COMMUNICATIONS • Control channel start-up (Phase 4) Select the maximum data signalling rate and trellis encoder and set the data signalling rate that can be supported. Transmitter/receiver Abbre- Signal Meaning Remarks viation PPh signal The other modem uses this signal to train the equalizer.
  • Page 223 G3 FACSIMILE COMMUNICATIONS • Control channel The conventional T.30 protocol is executed. The transmission speed is 600bps. Transmitter Abbre- Signal Meaning Remarks viation Flag flags Maintain synchroniza- 7E (H) tion. Non-standard Receive NSF from the facilities set- other party, select an available mode from it, and instruct reception.
  • Page 224 G3 FACSIMILE COMMUNICATIONS In the control channel, signals which differ according to the frequencies of both TX and RX are output. It follows that the effects of the echo are not received because the frequencies of the signal returned by echo and the signal output by the other machine are different.
  • Page 225 G3 FACSIMILE COMMUNICATIONS • Control channel resyncronization procedure (Communication end procedure) Protocol for terminating transmission. The transmission speed is 1200bps. Transmitter Abbre- Signal Meaning Remarks viation Sh signal Short training Sh signal ALT signal — E sequence — End of proce- PPS- One page is transmit- dures...
  • Page 226 G3 FACSIMILE COMMUNICATIONS (3) Examples of sequences The signals in the shaded areas are important in the protocol. • Late start Since the receiver cannot detect the CM signal while sending the ANSam signal, it sends the DIS signal containing the “V.8 protocol” declaration. The transmitter sends the CI signal to request the receiver to send the ANSam signal again to move to V.8 protocol.
  • Page 227 G3 FACSIMILE COMMUNICATIONS • Between-page sequence The transmitter sends image data, then the PPS-MPS signal in the same as for the T.30 protocol. The receiver sends the MCF signal to receive the next page. Image data Turn-off PPS-MPS flags flags flags "1"...
  • Page 228 Then the receiver sends the DIS signal and the transmitter sends the DCS signal to change the mode. Image data Turn-off PPS-EOM flags flags When Canon fax flags machines communicate with each other, a special procedure is used, so this protocol is omitted. flags flags flags "1"...
  • Page 229 G3 FACSIMILE COMMUNICATIONS • Image transmission speed change from the receiver The receiver returns to the PPh signal in response to the Sh signal from the transmitter. The image transmission speed is then determined by the MPh sequence sent from both modems. Image data Turn-off...
  • Page 230 G3 FACSIMILE COMMUNICATIONS • Image transmission speed change from the transmitter The transmitter sends image data, and then the PPh signal, and the receiver returns the PPh signal to the transmitter. The image transmission speed is then determined by the MPh sequence sent from both modems. Image data Turn-off...

  • Page 231: Transmission Control Procedures

    G3 FACSIMILE COMMUNICATIONS 6. TRANSMISSION CONTROL PROCE- DURES With G3 facsimiles, the document size, recording paper size, MODEM type and other factors differ according to the product. For this reason, G3 facsimiles use special signals to handle mutual information about func- tions and states on the transmitting and receiving sides.

  • Page 232: Signal Types

    G3 FACSIMILE COMMUNICATIONS Signal Types In G3 facsimile communications, various signals are used in addition to the previously described binary signals. Table 5-13 Signal Types Type of Signal Meaning Preamble signal Signal prefixed to binary signal Binary signal Signal expressed by 0 or 1 to communicate meaning of procedure Image signal Signal of coded image...

  • Page 233: Basic Transmission Control Procedure

    G3 FACSIMILE COMMUNICATIONS Basic Transmission Control Procedure This is the basic transmission control procedure in G3 communications. We recommend fully understanding this control procedure as it is the most basic of the procedures. Note, however, that operation differs on V.34 MODEM installed facsimiles as they use the V.8 procedure.
  • Page 234 G3 FACSIMILE COMMUNICATIONS 6.3.1 Tonal procedure Transactions are performed using only tonal signals, and whether the com- municating side is the G3 transmitting side or receiving side is notified. The tonal procedure is also called center identification or phase A. Calling Side (transmitter) Called Side (receiver) Dial...
  • Page 235 G3 FACSIMILE COMMUNICATIONS 6.3.2 Initial identification The facsimile transmits its own capabilities to the destination by using the initial identification. If optional signals are used, the indispensable DIS is transmitted last. Calling Side (transmitter) Called Side (receiver) Preamble Preamble Preamble ït Fig.
  • Page 236 G3 FACSIMILE COMMUNICATIONS 6.3.3 Receive command This command is transmitted after the initial identification or the transmit command is received from the other party. (For details on the transmit command, see 6.9.1 Polling (reception on calling side) (described later).) Overview When DIS is received from the receiver, the transmitter sends the DCS.
  • Page 237 G3 FACSIMILE COMMUNICATIONS 6.3.4 Training/Pre-message response By training, TCF is transmitted at the transmission speed by which images are actually transmitted after the receive command to check whether or not images will be transmitted without a transmission error occurring. The pre-message response is a response that is transmitted by the receiver that has received the receive command and training/TCF.
  • Page 238 G3 FACSIMILE COMMUNICATIONS 6.3.5 Message transmission This is the body of the image signal and comprises training, message and RTC. The message is transmitted from the transmitting side after it has been ver- ified that the CFR has been received from the receiving side and that train- ing has been performed correctly.
  • Page 239 G3 FACSIMILE COMMUNICATIONS 6.3.6 Post-message commands The transmitter notifies the other party that transmission has ended after the image signal has finished being transmitted. The signal to be transmitted sometimes changes when the next document is prepared or when the transmission mode is to be changed. In this exam- ple, EOP is transmitted as the image data is only one page.
  • Page 240 G3 FACSIMILE COMMUNICATIONS 6.3.7 Post-message responses The receiver transmits signals for notifying the transmitter whether or not that page could be received successfully at each reception of a single page. In this example, MCF is transmitted as the page was successfully received. RTP and RTN are also transmitted.
  • Page 241 G3 FACSIMILE COMMUNICATIONS 6.3.8 Other control signals Calling Side (transmitter) Called Side (receiver) Preamble Preamble Preamble Line disconnected Line disconnected Fig. 5-73 Other Control Signals These signals are for disconnecting the line, and do not require a response from the other party. Transmission Reception Binary Signal...

  • Page 242: Procedures For Performing Individual Page Control (Q Signals)

    G3 FACSIMILE COMMUNICATIONS Procedures for Performing Individual Page Control (Q signals) “EOP” is transmitted on the facsimile transmitting side as the signal for showing the end of one page’s worth of image. Nevertheless, as the way of sending on the transmitting side, there are times when multiple-sheet doc- uments are to be transmitted and the next page of the document is to be transmitted at a different resolution.
  • Page 243 G3 FACSIMILE COMMUNICATIONS EOP is transmitted when a document was transmitted continuously by EOM and MPS and there are no more documents to send. EOP is also transmitted when there is only one document sheet to transmit. When MCF is received from the other party, DCN is trans- mitted to disconnect the line.

  • Page 244: Training

    G3 FACSIMILE COMMUNICATIONS Training The compensation of line characteristics such as attenuation distortion or group delay distortion that occurs on telephone lines is “equalizing.” “Training” is the procedure where equalizing is performed to reliably transmit image signals. To be more precise, various pattern signals are out- put from the transmitting side at the same transmission speed as the image signals before the image signals are transmitted.
  • Page 245 G3 FACSIMILE COMMUNICATIONS by DCS. Delaying the transmission speed in this way when a communica- tions error has occurred at the current transmission speed is called “fall- back.” When FTT is returned (when TCF cannot be successfully received) even if fallback is repeated, the transmitting side judges that communica- tions is not possible on the current line, and the communications ends in error.

  • Page 246: Method For Detecting Image Signal Transmission Errors

    G3 FACSIMILE COMMUNICATIONS Method for Detecting Image Signal Transmission Errors Although image signals are sent after equalizing the MODEM and train- ing, a transmission error may occur when sudden noise or an instantaneous power interruption is generated during image signal transmission. To detect whether a transmission error has occurred in the image signal on the receiving side, the number of bits in each line after decoding is compared with the specified number of bits according to the document size (1728...
  • Page 247 G3 FACSIMILE COMMUNICATIONS from the next page onwards, DCS is returned to in the same way as RTN, a fallback is made to repeat the procedure from training again and the trans- mission speed is determined again to enable more reliable communica- tions.

  • Page 248: Option Signals

    This is an auto-dial Response facsimile. This is an auto-reception facsimile. This is a G3 facsimile. This is a Canon facsimile. Telephone number is XXXXX. ITU-T G3 mode This is a G3 facsimile. This is a Canon facsimile. Telephone number is XXXXX.

  • Page 249: Structure Of Binary Signals

    G3 FACSIMILE COMMUNICATIONS Transmission Reception Binary signal Signal (including user name and maker code) that communicates to the other party that transmission will be performed using a function other than that recommended by ITU-T (functions unique to manufacturer that are not provided in DCS). Transmission Reception Binary signal...
  • Page 250 G3 FACSIMILE COMMUNICATIONS 6.8.1 Preamble The preamble is the signal that prefixes the binary signal, and is a series of the flags for about 1 sec. A “flag” comprises eight bits “01111110” (7E when expressed in Hex), and the preamble comprises about 37 continuous flags.
  • Page 251 G3 FACSIMILE COMMUNICATIONS Address field Although this is used for the terminal device ID in data communica- tions, it is fixed to a single format for the facsimile. Format 11111111(=FF H) Remarks Signal for maintaining the format of HDLC Control field This is used to control the terminal device in data communications, and to determine whether that the frame is the final frame or not in the case of multiple frames.
  • Page 252 G3 FACSIMILE COMMUNICATIONS There are two types of frames, frames with a frame information field (FIF) and frames without. Sometimes multiple signals such as NSF, CSI and DIS are output as a continuous string to the transmission control signals. The control field (C) is used for identifying the final frame at this time.
  • Page 253 G3 FACSIMILE COMMUNICATIONS 6.8.3 Details of FCF The FCF for each signal is determined as shown in the following table. Table 5-14 Correspondence between Signal Name and FCF Signal Remarks Name Initial identification 00000100 FIF follows right after. 00000010 00000001 Transmit command 10000100 10000010...
  • Page 254 G3 FACSIMILE COMMUNICATIONS 6.8.4 Details of FIF FIF is used for incorporating information that cannot be expressed by FCF alone. As the format of FIF differs according to each signal, let’s describe FIF in order. • FIF of DIS, DTC The FIF of DIS and DTC has the same format and the same meaning.
  • Page 255 Extension field: (1) = FIF is extended by 8 bits after this bit. (0) = FIF is up to this bit. = “0” Uncompressed mode: (0) = Not provided, (1) = Provided, (0) on Canon machines ECM: (0) = Not provided, (1) = Provided = “0” = “0” = “0”...
  • Page 256 G3 FACSIMILE COMMUNICATIONS Table 5-15 FIF of DIS, DTC Bit No. Meaning/Function Extension field: (1) = FIF is extended by 8 bits after this bit. (0) = FIF is up to this bit. Sub-address capability: (0) = Not provided, (1) = Provided Password: (0) = Not provided, (1) = Provided Ready to send data file (polling) Pending...
  • Page 257 G3 FACSIMILE COMMUNICATIONS Table 5-15 FIF of DIS, DTC Bit No. Meaning/Function Single-layer sequential coding (recommendation T.85) optional L0: (0) = Not provided, (1) = Provided Extension field: (1) = FIF is extended by 8 bits after this bit. (0) = FIF is up to this bit. HKM key management capability: (0) = Not provided, (1) = Provided PSA key management capability: (0) = Not provided, (1) = Provided Override mode capability: (0) = Not provided, (1) = Provided...
  • Page 258 (0) = FIF is up to this bit. = “0” Uncompressed mode: (0) = Not provided, (1) = Provided, (0) on Canon machines ECM: (0) = Regular transmission, (1) = ECM transmission ECM frame size: (0) = 256 bytes, (1) = 64 bytes = “0”...
  • Page 259 G3 FACSIMILE COMMUNICATIONS Table 5-16 FIF of DCS Bit No. Meaning/Function = “0” T.43 coding selection: (0) = Selected, (1) = Not selected Plain interleave selection: (0) = Selected, (1) = Not selected Pending Pending Extension field: (1) = FIF is extended by 8 bits after this bit. (0) = FIF is up to this bit.
  • Page 260 G3 FACSIMILE COMMUNICATIONS Table 5-16 FIF of DCS Bit No. Meaning/Function Processable mode 26 (T.505) selection: (0) = Selected, (1) = Not selected Digital network capability selection: (0) = Selected, (1) = Not selected Full-duplex and half-duplex operation: (0) = For half-duplex operation only (1) = Full-duplex and half-duplex operation JPEG coding selection: (0) = Selected, (1) = Not selected Full color mode selection: (0) = Selected, (1) = Not selected...
  • Page 261 G3 FACSIMILE COMMUNICATIONS Table 5-16 FIF of DCS Bit No. Meaning/Function Pending for security in the future Pending Pending Pending Pending Extension field: (1) = FIF is extended by 8 bits after this bit. (0) = FIF is up to this bit. •...
  • Page 262 G3 FACSIMILE COMMUNICATIONS Example of telephone number: 01 2345 6789 9 8 7 6 5 4 3 2 1 1 0 0 1 1 0 0 Fig. 5-82 Content of FIF of CSI, CIG and TSI • FIF of NSF, NSC and NSS The FIF of NSF, NSC, and NSS contains the information for communica- tions between facsimiles made the same manufacturer in modes other than ITU-T...
  • Page 263 Japan: All bits “0” 3rd byte Maker code Code which indicates the name of the manufacturer. Canon code is 88H. (See Appendix 10. MAKER CODES TABLE.) From Free area Manufacturers can freely use this the 4th byte area.

  • Page 264: Example Of G3 Procedures

    G3 FACSIMILE COMMUNICATIONS Example of G3 Procedures 6.9.1 Polling (reception on calling side) “Polling” refers to the reception of the document currently loaded on the called side by the calling side. Calling Side (receiver) Called Side (transmitter) Dial Call Response "Start key is pressed to hear CED".

  • Page 265: Ecm Communications

    G3 FACSIMILE COMMUNICATIONS Calling side Called side Binary signal Signal for communicating the telephone number of the calling side to the called side. (option) Calling side Called side Binary signal Command for instructing transmission after receiving the DIS from the called side and verifying that there is a document loaded at the other party.
  • Page 266 G3 FACSIMILE COMMUNICATIONS of 256 frames that are in an HDLC structure, and partitions image data coded by the MH, MR, MMR or JBIG schemes into 256 bytes. Accord- ingly, a single data block is 64 kbytes. The content of the coded image is the same as in general G3 communications.
  • Page 267 G3 FACSIMILE COMMUNICATIONS Called Side (receiver) Calling Side (transmitter) Dial Call Response Training Frame 0 Transmission of 1st block Frame 1 (error not generated) Frame 2 Frame 255 End of transmission of block PPS-NULL Next block present Received successfully Training Frame 0 Frame 1 Error generated...
  • Page 268 G3 FACSIMILE COMMUNICATIONS 6.10.2 Structure of ECM image signals The content of coded images is the same as that in general G3 communica- tions. Fills, however, are not required as the image data is basically com- municated by memory transmission and reception. Each frames are numbered from 0 to 255.
  • Page 269 G3 FACSIMILE COMMUNICATIONS • PPR The receiving side informs the transmitting side of error frames by PPR in response to PPS-Q. MCF is returned when there are no errors. As a single block of image data has 256 frames, frames are assigned a frame number within the range 0 to 255.
  • Page 270 G3 FACSIMILE COMMUNICATIONS • CTC and CTR When there is an error frame however many times the same block is trans- mitted, delaying the image transmission speed will reduce the rate (error rate) at which errors occur. For this reason, the transmitter outputs CTC when PPR is received four times in the same block to notify the receiver that it will transmit (fallback) at a delayed image transmission speed.
  • Page 271 (when an error occurs even if the image transmission speed is delayed), the transmitter outputs the EOR to cancel re-transmitting of that block. Canon facsimiles do not output EOR until a fallback to 2400 bps is made. EOR is first output when the re-transmit is continued at 2400 bps and PPR is received.
  • Page 272 G3 FACSIMILE COMMUNICATIONS • RNR and RR On receivers whose printing speed is slower than the data receive speed, the receive buffer sometimes becomes full or busy. In this case, reception of the next block is not possible until new free memory appears after print- ing of already received blocks has ended.
  • Page 273 CHAPTER FACSIMILE SYSTEM 1. INTRODUCTION..............6-2 2. SCNT BOARD................6-3 System Control Section........... 6-3 Communications Control Section ........6-4 Reading Control Section ..........6-4 Printer Control Section ............ 6-4 3. NCU BOARD................6-5 Off-hook Detection ............6-6 Formation of DC Loop ............. 6-6 Detection of Calling Identification (CI) ......

  • Page 274: Chapter 6 Facsimile System

    FACSIMILE SYSTEM 1. INTRODUCTION This chapter describes the functions of the main printed circuit boards used on a facsimile. Mainly, the following printed circuit boards are used: • SCNT board for controlling the entire facsimile system • NCU board that acts as the facsimile’s interface with the telephone line •...

  • Page 275: Scnt Board

    FACSIMILE SYSTEM 2. SCNT BOARD “SCNT board” is an abbreviation of System CoNTroller board, and per- forms control of the entire facsimile system. The control functions of the SCNT board can be broadly classified into the following four control sec- tions: •...

  • Page 276: Communications Control Section

    FACSIMILE SYSTEM the DRAM and the MODEM, and between the system controller and the DRAM to reduce the load placed on the CPU. The system controller is the IC that controls peripheral devices. It converts the serial data that arrives from the reading section to parallel data and performs chip selection of peripheral ICs, amongst other operations.

  • Page 277: Ncu Board

    FACSIMILE SYSTEM 3. NCU BOARD “NCU board” is an abbreviation for Network Control Unit board. This board is located at the telephone line - facsimile interface. This board func- tions to detect signals arriving from the telephone line to transfer them to the MODEM on the SCNT board, and to switch the line between the fac- simile and telephone.

  • Page 278: Off-Hook Detection

    FACSIMILE SYSTEM The following describes the functions of the NCU board divided into basic functions. Detection of CI Off-hook detection H relay System controller Line signal monitor MODEM 2-wire/4-wire conversion S relay CML relay P relay Formation of Exchange DC loop Vref SCNT generation...
  • Page 279 FACSIMILE SYSTEM OFF within the telephone, DC current does not flow and the DC loop is not formed. On-hook Off-hook detection circuit H relay CML relay DC seiz To 2-wire/4-wire Exchange circuit conversion circuit NCU board Fig. 6-5 Formation of DC Loop (in standby state) DC current flows as the HS turns ON when the telephone is made off- hook, and a DC loop is formed between the exchange...
  • Page 280 FACSIMILE SYSTEM Off-hook detection circuit H relay CML relay DC seize To 2-wire/4-wire Exchange circuit conversion circuit NCU board Fig. 6-7 Formation of DC Loop on Facsimile Side 6–8...

  • Page 281: Detection Of Calling Identification (Ci)

    FACSIMILE SYSTEM Detection of Calling Identification (CI) The CI detection function detects the calling identification (CI) sent from the exchange. Normally, when dialing is performed from the calling party, the bell of the telephone on the incoming call side rings according to the CI from the exchange.

  • Page 282: Line Signal Monitor

    FACSIMILE SYSTEM Line Signal Monitor In the answering machine connection mode, the CML relay is switched to the telephone side in the same way as in a standby state so that the tele- phone line is connected directly to the telephone. However, when the call- ing party is a facsimile, the CML relay must be switched to facsimile for reception, and so the CML relay is switched to the facsimile side according to the signals arriving from the telephone line.

  • Page 283: Dial Control

    FACSIMILE SYSTEM Dial Control The dial control function generates dial pulses (DP). Application of ON/ OFF switching of relays is often adopted as a method of generating dial pulses. The following shows the basic configuration of the dial control cir- cuit.

  • Page 284: 2-Wire/4-Wire Conversion

    FACSIMILE SYSTEM 2-wire/4-wire Conversion Normally, telephone lines are 2-wire. However, 2-wire must be converted to 4-wire so that the send data can be processed separately from the received data internally on the facsimile. The 2-wire/4-wire conversion cir- cuit performs this conversion. Reception 2-wire/4-wire conversion...
  • Page 285 FACSIMILE SYSTEM A varistor is used as the protective circuit for overcurrent. Though varistors normally do not allow current to pass, they turn the CML relay ON when a high-voltage CI arrives from the telephone line, and so the current is allowed to escape to the line to protect the circuit elements from voltage rise.

  • Page 286: Telephone Connection Control

    FACSIMILE SYSTEM Telephone Connection Control In European regions, there are some countries where the line connection of the handset and the extension telephone to be connected to the facsimile is prioritized, and must be connected in parallel in accordance with the com- munication standards of that country.
  • Page 287 FACSIMILE SYSTEM Hello! Who's that calling? Hello! Who's Exchange that calling? Handset in use Extension telephone cannot be used. Hello! Who's Exchange that calling? Handset not in use (on-hook) Hello! Who's tha t calling? When the handset is made off-hook Extension telephone can be used.
  • Page 288 FACSIMILE SYSTEM • Non-prioritized connection (parallel connection) The relationship between the handset and the extension telephone is not prioritized, allowing a three-way conference call. Hello! Who's that calling? Hello! Who's that calling? Exchange Hello! Who's that calling? Fig. 6-17 Non-prioritized Connection 6–16...

  • Page 289: Relay Operations

    FACSIMILE SYSTEM Relay Operations The following describes operation of each of the relays. • CML relay (Connect Modem to Line relay) This relay is for switching between the facsimile and the telephone (hand- set or extension telephone) that is the core function of the NCU board. With regular relays, an instantaneous circuit interruption occurs at switch- ing.

  • Page 290: Opcnt Board

    FACSIMILE SYSTEM 4. OPCNT BOARD As the operation panel is the part that the user must touch to operate the facsimile, the OPCNT board in the operation panel is powered ON at all times to enable use of buttons on the operation panel. The OPCNT board is configured as follows: System OPCNT...
  • Page 291 FACSIMILE SYSTEM KOUT7~KOUT0 OPCNT control IC KIN7~KIN0 Fig. 6-19 Button Detection Matrix and Control IC To detect button input, the reference clock from the OPCNT control IC is divided so that the state of outputs KOUT0 to KOUT7 is Low for a fixed period of time.
  • Page 292 FACSIMILE SYSTEM For example, if button 23 is held down when KOUT2 becomes Low, KIN3 also becomes Low, and the OPCNT control IC detects that the button of the KOUT2 row and the KIN3 line has been pressed. KOUT7~KOUT0 Divided clock KOUT0 OPCNT...

  • Page 293: Led Lighting Control

    FACSIMILE SYSTEM LED Lighting Control The LEDs are connected to the ports on the OPCNT control IC as shown in the figure below. These ports are configured internally as drivers. When the LED lighting signal arrives from the MPU, the driver turns ON, and current flows to the LED to light the LED.

  • Page 294: Flow Of Image Signals

    FACSIMILE SYSTEM 5. FLOW OF IMAGE SIGNALS Transmission (1) Images are read by the contact sensor, and the resulting analog image data is sent to the SCNT board. (2) The analog image data that arrives from the contact sensor undergoes digital image data conversion, error diffusion processing or other pro- cessing on the image processor IC of the reading control section.

  • Page 295: Reception

    FACSIMILE SYSTEM Reception (1) Received data that arrives from the telephone line is amplified by the NCU board, and then sent to the MODEM on the SCNT board. (2) The MODEM demodulates the data, and writes the received data to DRAM.

  • Page 296: Power Supply Unit

    FACSIMILE SYSTEM 6. POWER SUPPLY UNIT The “power supply unit (regulator)” converts the alternating current (AC) for household use into a direct current (DC) constant voltage power source. A “constant voltage power source” refers to a power source whose output is maintained at a fixed output voltage even if the input voltage or output current fluctuate.
  • Page 297 FACSIMILE SYSTEM In other words, when the output voltage is higher than the reference volt- age, the duty ratio is lowered (the OFF time is increased), and when it is lower than the reference voltage, the duty ratio is raised (the ON time is increased) so that the output voltage is equal to the reference voltage at all times.
  • Page 298 FACSIMILE SYSTEM 6.1.1 Protective circuit The power supply circuit is provided with a protection function for over- current and overvoltage on the primary side. As protection against overcurrent, the power supply circuit is provided with a current fuse. When an overcurrent flows, this fuse blows due to self- heating, preventing overcurrent from flowing to the circuit from then on.
  • Page 299 FACSIMILE SYSTEM 6.1.2 Noise filter The noise filter comprises coils and capacitors, and cuts noise generated at the input section (line noise, etc.) and prevents switching noise from escap- ing to the power supply line. Input (power Output supply line side) Fig.
  • Page 300 FACSIMILE SYSTEM The diode bridge can also be represented as shown in Fig. 6-29. Fig. 6-29 Diode Bridge 6.1.4 Surge prevention circuit input is rectified by the diode bridge, and is charged in capacitor C. For this reason, a large surge current flows when the power is turned ON. A thermistor is used to prevent surge current from flowing as there is the dan- ger that elements on circuits may be destroyed when surge current flows.
  • Page 301 FACSIMILE SYSTEM 6.1.5 Oscillation/Control and output error amplification cir- cuits The oscillation/control circuit (IC1) is located on the primary side, and the output error amplification circuit is located on the secondary side. The out- put error amplification circuit detects the error with the reference voltage according to the fluctuation in the output voltage.
  • Page 302 FACSIMILE SYSTEM 6.1.6 Smoothing circuit is rectified using only a rectifier, the DC output contains a large pul- sating component. The circuit used to reduce this pulsating current and provide smooth stable DC voltage is called a smoothing circuit. Fig. 6-32 Pulsating Component Fig.

  • Page 303: Configuration Of Power Supply Unit On A Facsimile

    FACSIMILE SYSTEM Configuration of Power Supply Unit on a Facsimile The power supply unit on a facsimile, broadly speaking, supplies voltage to two or three power lines such as those below from the AC power for household use: • +5V for IC drive •...

  • Page 304: G4Cnt Board

    FACSIMILE SYSTEM 7. G4CNT BOARD The G4CNT board is provided on G4 facsimiles, and is the equivalent to the NCU board on a G3 facsimile. The G4CNT board performs connection with the ISDN line to perform digital communications. In the case of a G4 facsimile, G4 communications is performed.
  • Page 305 FACSIMILE SYSTEM V853 Slave CPU (V853) Dual port RAM (V821) Modem Codec ISDN interface HDLC controller To analog telephone SLIC Codec Fig. 6-34 System Block Diagram of G4CNT Board ït çi 6–33...
  • Page 306 Notes 6–34...

  • Page 307: Appendix

    APPENDIX APPENDIX 1. TRANSMISSION LINES OF TELEPHONE LINES ....A-2 2. CHARACTERISTICS OF TELEPHONE LINE (ANALOG) ..A-4 Telephone Line Band ............A-4 Characteristics of Telephone Network Components ..A-5 Factors of Telephone Line Deterioration ......A-6 3. FACSIMILE COMMUNICATION NETWORK SERVICES & MINIFAX (JAPAN ONLY) ............

  • Page 308: Transmission Lines Of Telephone Lines

    1. TRANSMISSION LINES OF TELE- PHONE LINES Let’s take a look at what is used as the transmission lines of an actual tele- phone lines. Fig. A-1 shows the transmission lines of a hierarchical organi- zation in Japan. Regional Center (RC) 4-wire coaxial cable system/optical fiber cable system or...
  • Page 309 Coaxial cable system Coaxial cable, which is an assembly of coaxial pairs with relatively low attenuation and superior high-frequency characteristics compared to 2- wire cable, is used. Among its various methods, the FDM-FM method which provides 1000 to 10000 channels, is adopted. Microwave radio relay system This system uses microwave radio in the 1 to 10 GHz band for transmis- sion.

  • Page 310: Characteristics Of Telephone Line (Analog

    2. CHARACTERISTICS OF TELEPHONE LINE (ANALOG) Telephone Line Band A human voice spectrum has the characteristics shown in Fig. A-3. Telephone line frequency band 2000 4000 6000 8000 10000 12000 Frequency (Hz) Fig. A-3 Voice Spectrum The greater part of voice energy is concentrated between 0 to 4000 Hz as shown in the Fig.

  • Page 311: Characteristics Of Telephone Network Components

    However, this bandwidth is too narrow for data transmission which requires a broad bandwidth such as facsimile transmission. So, coding and high-speed modulation technologies are used for facsimiles to transmit data at high speed in the limited narrow band. Characteristics of Telephone Network Components This item describes the characteristics of each component in a telephone network.

  • Page 312: Factors Of Telephone Line Deterioration

    “S/N” stands for the signal-to-noise ratio. It is also called the SN ratio. (For details, see this chapter, 5. S/N.) 2.2.2 Characteristics of exchange (1) Step-By-Step (SXS) Noise or Short breaks are more likely to occur as these exchange has many mechanical contacts.
  • Page 313 (3) Factors in international communications • Echo • Time taken for establishing line connection (4) Other factors • Lightning Though these factors do not cause major trouble in voice transmission, they sometimes are a problem in data transmissions such as facsimile transmission.
  • Page 314 Table A-1 Phenomenon Caused by Deteriorating Factors and Countermeasures Deteriorating Phenomenon Countermeasure Factor Group delay The image signals become more dif- — distortion ficult to receive just like as in atten- uation distortion. Level variation Lines are missed if the variation is Improve the S/N ratio.
  • Page 315 Table A-1 Phenomenon Caused by Deteriorating Factors and Countermeasures Deteriorating Phenomenon Countermeasure Factor Echo Control procedure errors may occur. Several countermeasures are avail- able. (See this chapter, 7.3 Echo.) Time taken for In international communications, it Insert a pause in the registered tele- establishing line may take a long time to connect phone number.

  • Page 316: Facsimile Communication Network Services & Minifax (Japan Only

    3. FACSIMILE COMMUNICATION NET- WORK SERVICES & MINIFAX (JAPAN ONLY) In facsimile communications over telephone lines, there is a tendency towards increasing communications speeds to keep costs down. Facsimiles are also being provided more and more functions to make them more con- venient.
  • Page 317 Subscriber exchange Subscriber exchange F-NET PSTN Subscriber exchange Fig. A-7 F-NET and PSTN çi A–11...

  • Page 318: F-Net

    F-NET F-NET is organized as shown in the Fig. A-8 for the following reasons: (1) Terminals and the network are considered to be integrated, and termi- nal functions are concentrated as far as possible on the network to improve terminal economy. (2) Many services can be achieved and line usage efficiency improved by adopting a storage and conversion system.
  • Page 319 3.1.1 Functions of facilities on F-NET The following describes the facilities and functions of the component ele- ments on F-NET. (1) Storage and conversion equipment (STOC) • Stores image signals. • Transmits and receives image signals with other STOCs. • Stands by and calls again when the incoming call terminal is busy. •...
  • Page 320 Two types of terminal are stipulated as being connectable to F-NET: Class 1 connection arrangement terminal and Class 2 connection arrangement terminal. Class 1 Connection Arrangement Terminal Terminal supporting the Minifax I mode Class 2 Connection Arrangement Terminal Terminal having an F-NET compatible G3 mode For details on the Minifax I mode, see this chapter, 3.2 Minifax I (MF-I).
  • Page 321 3.1.3 Description of connection operation on F-NET (1) When the caller dials the special number “161” on the telephone, the secondary dial tone (SDT) is returned from the LS. The caller then dials the called party number. (2) LS detects the caller number, and transmits this to the TS-FX on the calling side together with the called party number.

  • Page 322: Minifax I (Mf-I

    “Minifax I” originally is the name of Class 1 connection arrangement ter- minals for F-NET. The transmission method used on these terminals is also called “Minifax I (MF-I)”. Any simple mention of Minifax refers to Mini- fax I. Recent Canon facsimiles do not support communications with Minifax I. A–16...

  • Page 323: Minifax Ii (Mf-Ii

    Minifax II (MF-II) Facsimile machines called “Minifax II (MF-II)” are produced as Class 2 connection arrangement terminals for facsimile communications. The mode used here is the mode called “F-NET compatible G3” and is almost the same as ITU-T’s G3 standard. (1) Control procedure of G3 facsimiles supporting F-NET The Fig.
  • Page 324 The Fig. A-11 shows the procedure for sending to the terminal from F- NET. F-NET (FCAP) 1300 Hz FAX alert Detection of FAX 2.2~10sec signal alert signal 2100 Hz 2.6~4sec (NSF) (CSI) TRAINING TRAINING MESSAGE Line disconnection Fig. A-11 Control Procedure of F-NET Compatible G3 (F-NET to facsimile terminal) A–18...

  • Page 325: Telephone Line Band & Signal Spectrum

    4. TELEPHONE LINE BAND & SIGNAL SPECTRUM Although the bandwidth of regular telephone lines is 300 to 3400 Hz, the upper limit is 3000 Hz for submarine coaxial cables for international com- munications. This is for the efficient use of high-cost cables. Telephone line frequency Frequency...

  • Page 326: S/N

    5. S/N S/N (Signal to Noise) is the ratio of the signal power level to the noise power level at optional point on a telephone line. Measured waveform Telephone Telephone Exchange Fig. A-13 S/N Generally, S/N can be calculated by the following formula: Signal power[mW] S/N = 10 log [dB]...

  • Page 327: Polarity Inversion On Exchange

    6. POLARITY INVERSION ON EXCHANGE The Fig. A-16 shows the standard operation of an exchange in order to explain polarity inversion. This example is for an exchange operating in Japan. The polarity on the calling side is reversed simultaneously with the called party becoming offhook.

  • Page 328: Factors Which Cause Deterioration In Quality Of Facsimile Transmission

    7. FACTORS WHICH CAUSE DETERIO- RATION IN QUALITY OF FACSIMILE TRANSMISSION Usual Factors (1) Transmission loss “Transmission loss” is the amount that a signal transmitted from the trans- mitting terminal attenuates until it arrives at the receiving terminal. Trans- mission loss is expressed in dB. Transmission loss has the greatest influence on the quality of telephone conversations.
  • Page 329 L (Loading) S=Approx.1km Frequency (kHz) Fig. A-18 Loading cable Fig. A-19 Attenuation Characteristics of Non-loading Cable (2) Attenuation distortion “Attenuation distortion” is the distortion that occurs as a result of inconsis- tent transmission loss in the required frequency band. Attenuation distortion occurs between EOs (end offices) and on non- loaded subscriber lines.
  • Page 330 Frequency (kHz) Fig. A-21 Attenuation Characteristics of Subscriber Lines Number of links The “number of links” is the number of times that modulation (multiplex) is performed between exchanges in the telephone hierarchy at or above the EO stage. You can also think of this as the number of transit trunks between exchanges that a telephone conversation passes through.
  • Page 331 (4) Level variation “Level variation” refers to the signal level change according to time. (5) White noise “White noise” occurs in amplifier vacuum tubes, transistors and resistors, and is uniformly distributed among all frequencies. (6) Crosstalk “Crosstalk” is the voice signals you can hear on other lines that is caused by electromagnetic or inductive coupling.
  • Page 332 FDM stands for Frequency Division Multiplex. This is a multiplex system in which the available transmission bandwidth of a transmission line is divided by frequency into narrow bands. By this method, carrier waves of differing frequencies are modulated on the signal wave, and their single sidebands are arranged along the frequency axis.

  • Page 333: Unusual Factors

    Unusual Factors (1) Impulse noise “Impulse noise” is the irregular noise that occurs because of the contact points at an exchange. This noise is easily generated by step-by-step exchange that operate by mechanical contacts. Impulse noise is no problem in telephone conversations, except that it can be a little offensive to the human ear when it occurs.

  • Page 334: Echo

    (3) Phase hit “Phase hit” is the sudden phase fluctuation caused by fading on carrier equipment and on microwave transmission zones, or by the switching of the transmission line on a multiplex transmission line. Phase hit does not cause any special problems in telephone conversations. However, in G3 facsimile transmission, the same phenomenon as in phase jitter occur significantly.
  • Page 335 time, such phenomenon occur. That is, one’s own voice is reflected at the other party, and is heard after 0.6 sec and 0.2 sec, respectively. The time for the echo to return may reach 1.2 sec in the case of satellite communications.
  • Page 336 (2) Echo suppressor disabler (Standardized in ITU-T G.164) Problems may arise with the echo suppresor which is necessary for general telephone calls when carrying out data communication using the full- duplex system. For this reason, a device called a “disabler” for disabling the echo suppressor is built into the echo suppressor.
  • Page 337 (3) Echo Canceller (Standardized in ITU-T G.165) If the signal propagation delay time were not too long, if the echo return loss was not too low, and if the speakers would not frequently interrupt each other, then an echo suppressor would be sufficient. However, the echo return loss varies considerably from connection to connection.
  • Page 338 Add a tonal signal (1080 Hz, 0.5 sec) before the CED tone (selected by the SSSW). By adding a tone other than 2100±21 Hz before CED, disabling of the echo suppressor can be prevented. A tone of 1080 Hz is added on Canon facsimiles. Long distance transmission line Tonal signal (1080 Hz, 0.5 sec)
  • Page 339 (3) Countermeasures on both transmitter and receiver After transmitting binary signals, ignore the binary signals from the other party for 0.6 to 0.7 sec. (This function is provided on all Canon facsimi- les.) After transmitting each binary signal, ignore binary signals from the other party for 0.6 to 0.7 sec (differs according to model of facsimile) as shown...
  • Page 340 Long distance transmission line Preamble 0.6~0.7sec Preamble Training Preamble 0.6~0.7sec Training MESSAGE Preamble 0.6~0.7sec Preamble 0.6~0.7sec Preamble Fig. A-35 Countermeasures on Both Transmitter and Receiver A–34...

  • Page 341: Ratio, Db, Dbm & Dbv

    8. RATIO, dB, dBm & dBV (1) Ratio and dB There are two ways of comparing values: by ratio and by dB indication (logarithm indication). Circuit network where : Input power : Output power : Input voltage : Output voltage : Input current : Output current : Input impedance...
  • Page 342 • A very wide range of numerical values can be expressed as small numerical values by using dB. Small ratios can also be expressed con- veniently. Example: When the power ratio is 1, 0 dB is used; when 10, 10 dB is used, and when 100, 20 dB is used.
  • Page 343 where impedance of the measure- Voltage 20 log [dBm] 0.775V ment point is 600 ohm Let’s look at how dB and dBm are actually used. As shown in the Fig. A- 38, if we assume the presence of attenuation on the transmission line and the exchange, then the signal that is transmitted from the transmitter at a level of -13 dBm becomes -27.5 dBm at the receiver.
  • Page 344 Here, let us try calculating the relationship between dBm indication and dBV indication: 20 log – 20 log 0.775 = 20 (log – log 0.775 20 log × 20 log 0.775 0.775 That is, if we added 2.2 dB to the value of the dBV indication, the result is the dBm indication.

  • Page 345: Binary Signals Table

    9. BINARY SIGNALS TABLE Table A-4 Signal Table Format (B: binary signal, T: tonal signal) Abbreviation On facsimile that (* indicates Function first receives DIS option.) On opposite facsimile Signals transmit- Calling Tone T: 1100 Hz ted by transmitter Digital Command Signal B: FCF1=X100 0001 End of Message B: FCF1=X111 0001...
  • Page 346 Table A-4 Signal Table Format (B: binary signal, T: tonal signal) Abbreviation On facsimile that (* indicates Function first receives DIS option.) On opposite facsimile Signals transmit- CED* Called Station Identification T: 2100 Hz ted by receiver Confirmation to Receive B: FCF1=X010 0001 CIG* Calling Subscriber Identifica-...
  • Page 347 Table A-4 Signal Table Format (B: binary signal, T: tonal signal) Abbreviation On facsimile that (* indicates Function first receives DIS option.) On opposite facsimile Error correction Continue To Correct: B: FCF1=X100 1000 mode (ECM) Response to Continue to Cor- B: FCF1=X010 0011 exclusive signals rect:...

  • Page 348: Maker Codes Table

    10.MAKER CODES TABLE Maker codes are included in the NSS/NSF/NSC signals of the FIF. While each maker is indicated within the three bytes of the FIF, when the third byte is 00, the maker is indicated in the fourth byte. The codes included in the maker code are indicated as shown below.
  • Page 349 Table A-5 Maker Codes Hexadecimal Binary Company Name 88 ** 1000 1000 **** **** CANON 8A ** 1000 1010 **** **** SANYO 8C ** 1000 1100 **** **** SHARP 8E ** 1000 1110 **** **** TAMURA 90 ** 1001 0000 **** **** TOSHIBA...

  • Page 350: Standard Document Sizes

    11.STANDARD DOCUMENT SIZES Table A-6 and Table A-7 shows standard document sizes. Table A-6 ISO A-series Document Sizes Size (mm x mm) Remarks 841×1189 594×841 Size of an opened out newspaper 420×594 297×420 210×297 148×210 105×148 Table A-7 ISO B-series Document Sizes Size (mm x mm) Remarks 1030×1456...

  • Page 351: G3 Facsimile Transmission Control Procedures

    12.G3 FACSIMILE TRANSMISSION CON- TROL PROCEDURES Transmitting station Transmit COMMAND T1 elapsed? NSP REQ? REC? Go to non- specified DIS or DTC? procedures COMPT REMOTE REC? DOC TO XMIT? Transmit (TSI)(NSS) MODE or(TSI)(DCS) COMPT REMOTE XMTR? Transmit trsining TCF çi Error correction? RESPONSE...
  • Page 352 Transmitting station Tranamit MPS(PRI-MPS) LAST DOC? RESPONSE REC? Interrupt 3RD TRY? CHANGE PIN or PIP? MODE? Transmit EOP Transmit EOM MCF? (PRI-EOP) (PRI-EOM) RESPONSE RTP? RESPONSE REC? REC? 3RD TRY? 3RD TRY? RTN? PIN or PIP? PIN or PIP? Alert operator MCF? MCF? T3 elapsed?
  • Page 353 Transmitting station END OF PAGE? LAST DOC? Interrupt CHANGE MODE? Fig. A-41 Transmitting Station Procedure 3 çi A–47...
  • Page 354 Transmitting station Transmit PPS-NULL RESPONSE 3RD TRY? REC? PPR? 4TH PPR? RNR? CONTINUE TO CORRECT? RESPONSE MCF? REC? RESPONSE REC? Transmit training Transmit error frames Transmit RCP Fig. A-42 Transmitting Station Procedure 4 A–48...
  • Page 355 Transmitting station Transmit PPS-MPS (PPS-PRI-MPS) RESPONSE 3RD TRY? REC? PPR? 4TH PPR? RNR? CONTINUE TO CORRECT? RESPONSE MCF? REC? RESPONSE REC? PIP or PIN? Transmit training çi Transmit error frames Transmit RCP Fig. A-43 Transmitting Station Procedure 5 A–49...
  • Page 356 Transmitting station Transmit PPS-EOP (PPS-PRI-EOP) RESPONSE 3RD TRY? REC? PPR? 4TH PPR? RNR? CONTINUE TO CORRECT? RESPONSE MCF? REC? RESPONSE REC? PIP or PIN? Transmit training Transmit error frames Transmit RCP Fig. A-44 Transmitting Station Procedure 6 A–50...
  • Page 357 Transmitting station Transmit PPS-EOM (PPS-PRI-EOM) RESPONSE 3RD TRY? REC? PPR? 4TH PPR? RNR? CONTINUE TO CORRECT? RESPONSE MCF? REC? RESPONSE Go to beginning REC? of phase B PIP or PIN? Transmit training çi Transmit error frames Transmit RCP Fig. A-45 Transmitting Station Procedure 7 A–51...
  • Page 358 Transmitting station END OF PAGE? LAST DOC? CHANGE MODE? Fig. A-46 Transmitting Station Procedure 8 A–52...
  • Page 359 Transmitting station Transmit EOR-NULL RESPONSE 3RD TRY? REC? RNR? RESPONSE ERR? REC? CONT WITH NEXT MSG? çi Fig. A-47 Transmitting Station Procedure 9 A–53...
  • Page 360 Transmitting station Transmit EOR-MPS (EOR-PRI-MPS) RESPONSE 3RD TRY? REC? RNR? RESPONSE ERR? REC? CONT WITH NEXT PIN? MSG? Fig. A-48 Transmitting Station Procedure 10 A–54...
  • Page 361 Transmitting station Transmit EOR-EOP (EOR-PRI-EOP) RESPONSE 3RD TRY? REC? RNR? ERR? RESPONSE REC? PIN? çi Fig. A-49 Transmitting Station Procedure 11 A–55...
  • Page 362 Transmitting station Transmit EOR-EOM (EOR-PRI-EOM) RESPONSE 3RD TRY? REC? RNR? ERR? RESPONSE REC? CONT PIN? WITH NEXT MSG? Go to beginning of phase B Fig. A-50 Transmitting Station Procedure 12 A–56...
  • Page 363 Receiving station Transmit (NSF) (CSI) DIS (NSC) (CIG) DTC RESPONSE 3RD TRY? T1 elapsed? REC? Go to non-specified procedures Error COMMAND T2 elapsed? EOM? 3RD TRY? correction? REC? LOCAL DTC? CARRIER INT? REC? DIS? Receiver training Receive phasing DCS? training TCF çi Error Receive facsmile...
  • Page 364 Receiving station PRI-Q? Alert operator LINE REQ? 3RD PRI-Q? MPS? Transmit PIN or PIP EOP? COPY QUALITY Phone to line EOM? Transmit PIN Transmit PIP OK to continue? LOCAL INT? Go to beginning of phase B COPY QUALITY REPHASE TRAIN? Respond RTN Respond MCF Respond RTP...
  • Page 365 Receiving station PRI-Q? ALERT OPERATOR CTC? Respond CTR LINE REQ? T3 elapsed? Transmit PIN Transmit PIN or PIP Transmit PIP çi Phone to line OK to continue? Go to beginning of phase B Fig. A-53 Receiving Station Procedure 3 A–59...
  • Page 366 Receiving station PPS-PRI-Q? COPY QUALITY PPS-Q? COPY QUALITY Respond PPR RECEIVE READY? END OF Respond RNR PAGE? COMMAND LOCAL INT? REC? ALERT T2 elapsed? Transmit PIP OPERATOR LINE REQ? RR or Respond MCF PPS-PRI-Q? PPS-Q? Fig. A-54 Receiving Station Procedure 4 A–60...
  • Page 367 Receiving station EOR-PRI-Q? EOR-Q? RECEIVE READY? END OF Respond RNR PAGE? LOCAL COMMAND INT? REC? ALERT T2 elapsed? Transmit PIN OPERATOR çi LINE REQ? RR or Respond ERR EOR-PRI-Q? EOR-Q? Fig. A-55 Receiving Station Procedure 5 A–61...
  • Page 368 Receiving station Last post message command PPS-Q? VII a Fig. A-56 Receiving Station Procedure 6 A–62...
  • Page 369 RESPONSE REC? Enter T4 delayed? Flag? Receive a frame? Signal gone? 3 second FCS error? delayed? 3s delayed? Signal gone? CRP? 200 ms delay? Transmit DCN? çi Disconnect the line Optional Process optional 200 ms response? response delay? Return "Yes" Return "No"...
  • Page 370 COMMAND REC? Enter Flag? Reset 6s timer T2 Receive a frame? Signal gone? FCS error? 3s delay? Signal gone? 3s delay? 200 ms delay? 200 ms delay? DCN? Disconnect line Optional CRP option? Return "No" command? Process optional Respond CRP command Return "Yes"...
  • Page 371 RESPONSE REC? Enter T5 elapsed? Transmit RR RESPONSE REC? 3RD TRY? Return (No) Return (Yes) Fig. A-59 RR Response Reception çi A–65...
  • Page 372 RESPONSE REC? Enter SET MODE Transmit CTC RESPONSE REC? 3RD TRY? CTR? Return (Yes) Return (No) Fig. A-60 CTC Response Reception A–66...

  • Page 373: Glossary

    GLOSSARY GLOSSARY or a digital terminal is sometimes con- nected to an ISDN line. AC (Alternating Current) Current whose direction of flow is inverted periodically. Device Answering machine connection mode This function is for automatically judging whether the incoming call is a facsimile or Capillary phenomenon a telephone call when the answerphone is The phenomenon where the level of a liquid...
  • Page 374 GLOSSARY DMA (Direct Memory Access) Transfer Friction coefficient A system internal function, transfer of data groups (memory blocks) that does not pass The ratio between the friction force parallel through the CPU. DMA transfer can speed to a contacting surface acting on contacting up system performance as it does not place parts and the force acting perpendicularly a load on the CPU.
  • Page 375 GLOSSARY Horizontal scanning parts with different functions, the I/O unit, control unit and arithmetic logic unit Reading of documents in the horizontal (ALU). direction is called “horizontal scanning,” and the number of pixels per unit length when the horizontal scanlines are separated into pixels is called the “horizontal scan- Non-feed ning density”...
  • Page 376 GLOSSARY RFC (Requests for Comment) This document issued by the IETF relates to technical information for the Internet, and comprises further documents that are identified by number. RFC describes proto- col sets or HTML language. RTC stands for Real Time Clock, the clock circuit that counts date and time.

  • Page 377: Index

    INDEX INDEX CM 5-76 ABC 3-15 CML relay 6-17 Actuator 4-19 CNG 5-76, 5-92 ADF 3-4 Coding scheme 5-6 A/D conversion circuit 3-15 Color facsimile 2-23 AGC 3-14 Communications control section 6-4 AM 5-46 Compression method 5-6 Amplitude modulation 5-46 Condensing lens 4-34 Amplitude shift keying 5-45 Contact resistance 1-6...
  • Page 378 INDEX Drum cleaning step 4-36, 4-45 G4CNT board 6-32 DTC 5-123 GENESIS 3-16 Dual tone multi frequency 1-11 Grade 1-20 Duty ratio 6-24 Group 2-3 Echo A-28 H relay 6-17 ECM 5-123 Half-duplex communication system A-5 Edge emphasis 3-16 Handset 1-2 Electronic exchange 1-26 HDLC 5-108 Electrophotographic method 2-20...
  • Page 379 INDEX Maintenance jet 4-57 PPS-EOM 5-126 Maker code A-42 PPS-EOP 5-83, 5-126 Make-up code 5-12 PPS-MPS 5-126 MCF 5-83, 5-98 PPS-NULL 5-126 Mesh network 1-16 PPS-Q 5-126 Message 5-96 Preamble 5-90 MH 5-9, 5-10 Pre-scan 3-14 Minimum transmission time 5-6 Primary charging step 4-35, 4-37 mm/inch conversion 4-8 Printer control section 6-4...
  • Page 380 INDEX Run length 5-10 Transit trunk 1-19, 1-24 Transmission control procedure 5-89 S relay 6-17 Transmission speed 5-5 SCNT board 6-3 Transmission time 5-5 Series regulator 6-24 Traversal trunk 1-24 Shading memory 3-15 Trellis coding 5-56 Sheet reading 3-3 TSI 5-81, 5-107 Shift 5-46 Two-dimensional coding scheme 5-17 Signal 5-99...
  • Page 381 Printied on paper that contains 60% reused paper. PRINTED IN JAPAN (IMPRIME AU JAPON) 0400AB0.40-0 CANON INC.

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