Canon LBP-2000, Service Manual

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CHAPTER 2
2 - 46
V. PICKUP/FEEDING SYSTEM
A. O u t l i n e
The presence/absence of paper in the multifeeder tray is detected by the multifeeder tray paper
sensor (PI102), and the presence/absence of paper in the cassette is detected by the cassette
paper sensor (PI104).
The size of paper inside the cassette set in the Printer and the presence/absence of the cassette
are checked by the paper size detecting switch (SW105) inside the Printer.
When the cassette is used as the source of paper, the cassette pickup clutch (CL101) goes on
while the main motor is rotating, causing the cassette pickup roller to rotate to feed a sheet of
p a p e r.
When the multifeeder tray is used, the multifeeder pickup solenoid (SL101) goes on while the
main motor is rotating, causing the manual feed pickup roller to rotate to feed a single sheet of
p a p e r.
When the paper moves past the registration paper sensor (PI101) and reaches the registration
roller, it is stopped and is made to arch on its leading edge, thus ridding itself of any skew.
Thereafter, the registration clutch (CL102) goes on to move the paper farther.
A specific period of time after the registration paper sensor (PI101) goes on (as set by the leading
edge registration adjusting volume VR101 on the DC controller), the vertical sync signal (/TOP) is
sent by the DC controller to the video controller.
A specific period of time after the video controller receives the /TOP signal, video signals (/VDO,
VDO) are sent, and the leading edge of the paper is matched against the leading edge of the image
on the surface of the photosensitive drum. Thereafter, the paper is moved through the transfer,
separation, and fixing blocks for face-down delivery.
The paper path is equipped with 2 photointerrupters (PI101, PI103) to monitor the arrival or
passage of paper. If the paper fails to reach or move past either of these sensors within a specific
period of time, the microprocessor (CPU) on the DC controller will identify the condition as indicat-
ing a jam, and will inform the video controller of the presence of a jam.