Service manual

COPYRIGHT © 1999 CANON INC. CANON GP160 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 7 PICK-UP/FEEDING SYSTEM
7-12
V. PAPER FEEDING OPERATION
A. Paper leading edge detection
The paper sent from the pick-up assembly is sent to the transfer area by the registra-
tion clutch (CL302) rotation.
A sensor is installed in front of the transfer area which detects the leading edge of
the paper sent from the registration roller. The DC controller PCB sends a vertical syn-
chronizing signal (TOP*) to the image processor PCB when the paper leading edge sen-
sor (PS301) detects the paper’s leading edge.
A designated period of time after the image processor PCB receives the TOP* sig-
nal, it sends out a video signal (VDO*, VDO) which causes the image on the photosen-
sitive drum and the paper’s leading edge to coincide.
After this, the paper passes through the transfer, separation and fixing areas, and is
then delivered onto the eject tray.
B. Paper width detection
The unit’s cassette size detection is judged by the position of the cassette paper size
lever which the user has set in the unit.
In the event of the paper size (width) in the cassette and the setting of the paper size
lever differing from each other, the paper size sensor (PS304) detects this and a paper
width detection signal (PS304S) will be sent to the DC controller PCB which will stop the
feeding operation.
Due to this, even if smaller paper (widthwise) than set by the cassette size lever is
fed through, the toner developed on the photosensitive drum will not adhere to the edge
of the transfer charging roller, therefore internal machine soiling caused by the toner is
prevented.
Figure 7-501
[2] PS301S
DC controller PCB
Image processor PCB
[3] TOP*
[4] VDO
[4] VDO*
Transfer charging roller
Registration roller
Paper leading edge sensor (PS301)
[1] PS304S
Paper width sensor (PS304)
[1] PS304S: Paper width detection signal
[2] PS301S: Paper leading edge detection signal
[3] TOP*: Horizontal synchronized signal
[4] VDO/VDO*: Video signal
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