Toner Cartridge - Sharp FO 4400 - B/W Laser - All-in-One Service Manual

8. LASER EXPOSURE
Laser exposure is the process of creating an invisible static charge im-
age on the PC Drum by the laser beam emitted from the Print Head
Unit. This process is controlled as follows in order to appropriately time
image printing.
In the sub-scanning direction (vertical direction)
· When the printer receives the PRINT signal, the Polygon Motor and
the Main Motor rotate and the paper is fed into the printer.
· The printing in the sub-scanning direction is started when the
Controller PWB sends the VIDEO signal to the Print Head a certain
time after the leading edge of the paper activates the Paper Sensor
(TOD signal).
· The print starting position for the 2nd line is decided by delaying the
VIDEO signal sending timing.
In the scanning direction (horizontal direction)
· The SOS Sensor is installed on the Laser Diode Control PWB to unify
the laser emission timing for each scan line.
9. DEVELOPMENT
9-1. Overview
Toner is applied to the invisible static image on the PC Drum and a toner
image (developed image) is created on the drum surface.

Toner Cartridge

1
2
7
VBL
No. Part Name
1 Toner Hopper
2 Toner Agitating Screw
3 Toner Transport Roller
4 Sleeve Roller
5 Resin Sleeve
6 PC Drum
7 Toner Blade
8 Bias Seal
6
5
4
3
6
4
3
8
VB
VSS
Contains toner.
Agitates the toner in the Toner Hopper and sends the toner to the Toner Transport Roller.
Transports the toner to the Sleeve Roller.
Turns the Resin Sleeve.
Carries the toner to the PC Drum surface for development.
Exposed to laser to create an invisible image and rotates to carry the developed image to the paper surface.
Spreads a thin, even coat of toner over the Resin Sleeve. The toner is negatively charged when passing
between this Blade and the Resin Sleeve.
Separates toner, which has not been attracted to the PC Drum, from the Resin Sleeve and returns it back to
the Buffer Section.
Print Head Unit
7
8
Developing Lower Seal Voltage terminal (VSS)
Developing Voltage terminal (VB)
Developing Blade Voltage terminal (VBL)
Fig. 8
Function
3 – 5
Charged Surface
Reflector Mirror
Laser exposed surface:
approx. -50V
SOS Sensor
Laser Diode
Polygon Motor (M3)
Fig. 7
VSS: DC-300V (DC-400 V max.)
VB: DC-300V (DC-400 V max.)
VBL: DC-550V (DC-700 V max.)
FO-4400U
FO-CS1
PC Drum
PWB-D