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CHAPTER 3 EXPOSURE SYSTEM
COPYRIGHT
©
1999 CANON INC. CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
3-5
Description
• Provides a means of reference for
determining forward movement
distance.
• Stops the scanner moving in re-
verse in 0.1 sec.
Scanner sensor
PS1(scanner
home position
sensor)
Signal
SCHP
Scanner
Forward Reverse
Table 3-102
Figure 3-105
Copy Start key
Power switch
ONON
STBY
INTR
SCFW
Forward
SCFW
SCRV
LSTR
STBY
Scanner home position
sensor (PS1)
Scanning lamp(LA1)
Scanner
III
SCRV
I
Reverse
Pre-registration roller
paper sensor (Q751)
I : Scanner home position detection
II : Lens home position detection
2. Relationship between Scanner Sensor and Signal
3. Basic Sequence of Operations (scanner)
The microprocessor on the DC controller PCB controls the forward movement distance of the
scanner with reference to the falling edge of the scanner home position signal. The forward move-
ment distance of the scanner varies according to the length of copy paper and reproduction ratio. If
the ratio is less than 130%, the scanner is moved forward as if for A4 (297 mm); if it is 130% or
more, the scanner is moved forward as if for LTR (279 mm).
For descriptions on how length is detected, see p. 5-10.