Canon 1000 Service Manual page 113

The video signals are synchronized for the sub scanning direction by the video controller based on the
image leading edge signal (ITOP). The ITOP signal is triggered by the output of the transfer belt home
position sensor, and the timing of output varies according to paper size. When the ITOP signal is generated,
the read enable signal for each color (YMRE in the case of Figure 3-411) causes the video signals (YMCBk)
to be read from the page memory area for transmission to the video controller. (As can be learned from the
timing chart, the read enable signal for each color is given a delay for the distance between drums.)
The video signal is forced to remain '0' until the print area signal (YFRM in Figure 3-411) is generated,
thereby creating a leading edge margin.
DC controller PCB
Memory PCB
Image leading edge signal
(ITOP)
Y read enable signal (YMRE)
Y print enable signal (YPE)
Y print area signal (YFRM)
M read enable signal (MMRE)
M print enable signal (MPE)
M print area signal (MFRM)
COPYRIGHT © 2001 CANON INC.
Video controller PCB
ITOP signal
Memory read
signal (MRE)
Video signal
Y,M,C,Bk
Figure 3-411
1st page
Paper length
(feeding direction)
Drum distance
Figure 3-412
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
Print area signal
Sub scanning
sync control
Density correction
Video signal
Test pattern
Y,M,C,Bk
Image area
1st page
Paper length
(feeding direction)
Image area
3. OPERATION AND TIMING
Video signal
Y,M,C,Bk
2nd page
3-69