Canon 1000 Service Manual page 121

The pattern on the transfer belt is exposed by a LED and read by a special CCD.
The image data is sent to the DC controller, and a histogram (Figure 3-425) is prepared for both main
and sub scanning directions. The coordinates of the center of the pattern is computed based on the data. In
the case of Figure 3-425, the center in the main scanning direction is the 128th pixel and that in the sub
scanning direction is the 130th line.
Feeding
direction
COPYRIGHT © 2001 CANON INC.
(front of copier)
Mirror
CCD
LED
Transfer belt movement
Figure 3-424
CCD array
0line
130th line
Figure 3-425
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
Image data
DC controller
ON signal
PCB
Pattern
Accumulated value
256th line
3. OPERATION AND TIMING
256th pixel
128th pixel
0th pixel
3-77