Canon LBP 2460 - B/W Laser Printer Service Manual page 123

3. Side Registration Adjustment System
When duplex printing, the center of the horizontal scanning direction for the second time print is
aligned with the center of the printable area on the drum with side registration adjustment. This
adjustment is conducted directly after duplex feed roller 1 starts to rotate, to make sure that the
edges of the page are aligned to the side registration guides.
The side registration guide home position sensor (PS23) detects whether or not the guides are
in their home position.
When the power is turned ON, the CPU drives the side registration motor to return the guides
back to their home position. If the guides are already in their home position when the power is
turned ON, they are moved slightly, then returned to the home position.
When a print is sent to the duplexing unit with the switchback roller (rotating clock wise), the
CPU turns ON the duplex feed clutch approx.0.6 second after activating the motor CW. The
print is then fed until the duplex feed roller 1 home position is detected by its home position
sensor (PS24). When detected, the CPU turns OFF CL21, and the paper is stopped. Following
this, the CPU activates the switchback roller pressure release solenoid (SL21), releasing pressure
from the roller. This completes preparation for the side registration adjustment operation.
The CPU drives the side registration motor (SMT22) at its specified pulse rate based on the
paper size information received from the DC controller. The side registration guides are then
moved according to the size of paper being used, and registration adjustment (*note) takes place.
The side registration guides are returned to their home position at a set time after the print has
been fed and the leading edge has been detected by the duplexing unit paper sensor (PS21).
SMT22 is a stepping motor, enabling it to accurately control the movement of the side
registration guides.
The CPU notifies the video controller via the DC controller of a side registration guide
malfunction when the side registration guides take longer than the regulated maximum
movement allowance after the home position detection begins.
Note: When the size of paper is anything other than A3, Ledger, A4 (landscape), Letter
(landscape) or B4, the distance that the side registration guides move is lengthened.
Therefore, the CPU drives SMT22 while the switch-back roller is rotating CCW, then
moves the registration guide. When the paper size is A3, Ledger, A4 (landscape), Letter
(landscape) or B4, at the point at which the CPU rotates the switch-back roller in a
clockwise direction, it drives SMT22 and moves the side registration guides move
quickly.
CHAPTER 2
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