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2001 CANON INC. 2000 2000 2000 2000 CANON iR2200/iR2800/iR3300 REV.0 MAR. 2001
CHAPTER 3 LASER EXPOSURE SYSTEM
3-5 P
3 Laser Driver Circuit
3.1 Controlling the Laser Unit
The laser driver circuit is used to drive the semiconductor laser according to the laser
drive signal from the DC controller PCB.
The laser driver circuit performs the following:
1. Turning on/off the laser.
2. Controlling the light intensity of the laser (APC control).
The signals have the following meanings and functions:
[1] Laser drive signal; used to drive the semiconductor laser.
[2] Sample laser activation signal; used to turn on the laser for intensity sampling (the result
is used for activation for imaging).
[3] Laser enable signal; goes ‘0’ when the laser is ready after the Start key is pressed.
[4] Image leading edge signal; used to start laser writing when paper reaches the image
leading edge sensor (PS12) mounted in front of the photosensitive drum.
[5] Used to monitor the laser intensity when the laser is turned on for sampling, and feeds
back the level appropriate to the intensity to the laser driver circuit.
[6] Used to control the output so that the feedback level and the reference level from the DC
controller will be identical.
[7] Laser intensity reference signal; used as the laser activation reference level determined
by the DC controller.
[8] Horizontal registration paper detection signal; used to adjust the image position by
changing the timing of laser activation with reference to the result of detection of the
edge of paper re-picked in double-sided mode by the horizontal registration sensor
(PS11).