Canon CANOSCAN D1230 series Service Manual page 32

2. FAU Lamp Lighting Circuit
When the host computer sends a film scan command, ASIC turns the scanning lamp lighting
signal (LAMP) OFF then turns FAU lamp lighting signal (XPA) ON to light the FAU lamp.
The FAU lamp light is converted into a flat light source by a light guide plate, then diffused via
1st diffusive film, brightness enhancement film and 2nd diffusive film. As a result, exposed
light from a transparent plate has equal light intensity which transmits a film and focuses on
the CCD in the scanning unit.
The FAU lamp also has a lamp OFF function for energy saving as in the case of the scanning
lamp.
3. Infrared LED Lighting Circuit
When the host computer sends a command to light an infrared LED, ASIC turns IRLED signal
ON to light the infrared LED.
The infrared LED light is converted into a flat light source by a light guide plate as in the case
of the FAU lamp, which transmits a film via 1st diffusive film, brightness enhancement film,
2nd diffusive film and transparent plate.
FAU
Inverter
PCB
Scanner
XPA
Host
Computer
©
COPYRIGHT 2001 CANON INC. CANOSCAN D1230U/D2400U REV.0 MAR. 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
FAU Lamp
IRLED
IRLED
ASIC
Main PCB
Figure 2-8
CHAPTER 2
Reflective Film
Light Guide Plate
1st Diffusive Film
Brightness
Enhancement Film
2nd Diffusive Film
Scanning Unit
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