Paper Pick-Up Unit - Canon LBP 2460 - B/W Laser Printer Service Manual

B. Paper Pick-up Unit
1. Cassette feed
Presence of the upper and lower cassettes is detected by the upper cassette sensor (PS1202) and
lower cassette sensor (PS1201). The presence of paper is detected by the upper cassette paper-
out sensor (PS1207) and lower cassette paper-out sensor (PS1208). The paper size is detected by
the four upper and lower cassette paper-size sensing switches (SW1601 to SW1604) installed in
the upper and lower cassettes. Table 2-5-1 lists combinations of cassette paper-size sensing
switches.
The paper level in the upper cassette is detected by combinations of outputs from the upper
cassette paper-level sensor 1 (PS1205) and upper cassette paper-level sensor 2 (PS1206). The
paper level in the lower cassette is detected by combinations of outputs from the lower cassette
paper-level sensor 1 (PS1203) and lower cassette paper-level sensor 2 (PS1204). Figure 2-5-3
shows combinations of PS1205, PS1203, PS1206, and PS1204.
When the video controller inputs the /PRNT signal into the printer, the cassette pick-up motor
(SMT1) starts operation. The cassette pick-up motor is a stepping motor, when rotating
clockwise, it drives the cassette pick-up roller, feed roller 1, and separation roller on the upper
cassette to enable printer to feed paper from the upper cassette. When it rotates counter
clockwise, it drives the cassette pick-up roller, feed roller 1, and separation roller on the lower
cassette to enable the printer to feed paper from the lower cassette.
Following this, the cassette pick-up solenoid (SL1) turns on, the main motor then drives the
cassette pick-up roller lowering cam to lower the cassette pick-up roller to the paper surface.
Paper is fed by the rotating cassette pick-up roller.
The paper picked up by the cassette pick-up roller is fed into the printer by feed rollers 1 and
2. If more than one sheet is picked up, unnecessary sheets are discharged by the separation
roller.
The paper passes through the pick-up unit paper sensor (PS2), the registration paper sensor
(PS1) and then reaches the registration roller. The registration roller does not rotate, so the paper
is stopped. The leading edge of the paper is looped to correct any skew. When the VERTICAL
SYNC signal (/VSYNC) is received, the registration clutch (CL1) turns on and the paper is fed
again.
Paper size
Ledger
A3
B4
Legal
Letter
A4
Table 2-5-1
Cassette paper-size sensing switch
SW1601 SW1602 SW1603
OFF OFF OFF
OFF ON OFF
ON OFF OFF
ON ON OFF
OFF OFF OFF
OFF OFF ON
CHAPTER 2
SW1604
OFF
OFF
OFF
OFF
ON
OFF
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