Service manual

CHAPTER 2
2 - 7 COPYRIGHT  2002 CANON INC. CANOSCAN 8000F REV.0 OCT. 2002 PRINTED IN JAPAN (IMPRIME AU JAPON)
B. Lamp Lighting Circuit
1. Scanning Lamp Lighting Circuit
When the scanner is powered on, or the host computer sends a scan command, ASIC turns
the scanning lamp lighting signal (LAMP) ON to light the scanning lamp.
The reflected light from the document is focused on the light-sensitive device CCD (charge-
coupled device) via the five mirrors, lens and FARE unit.
The scanner is provided with a lamp OFF function for energy saving. A built-in timer to be
set by the device driver is counted during lamp ON and turns the scanning lamp OFF when no
scan command is sent for a certain period.
Figure 2-6
Host
Computer
ASIC
GND
CCD
PCB
GND
Inverter
PCB
Scanning Lamp
Main PCB
LAMP
CCD
Document Glass
Lens
FARE Unit
Scanning Unit