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3: Operation
3-16
Colorwriter LSR 2000 Printer
Service Guide
Laser/scanner system
Figure 3-8
Laser/scanner system
When the /PRNT signal is sent from the video controller, the DC
controller performs Automatic Photoemission Control (see “Initial
APC” on page 3-20) to stabilize the intensity of the laser beam.
Upon completion of APC, the DC controller generates 8-bit video
data signals (Dv2-Dv9) in accordance with the video signals
(/VDO0-/VDO7) sent by the video controller and then sends them
to the PWM-IC in the laser/scanner unit. According to the laser
drive signal (internal signal in the laser/scanner unit) output from
the PWM-IC, the laser driver circuit turns the laser diode on and
off to produce the modulated laser beam.
The modulated laser beam is converted to a parallel beam with the
collimator lens and cylindrical lens. The beam then strikes the
scanning mirror which is rotating at a constant speed.
The laser beam, reflected by the scanning mirror, focuses on the
photosensitive drum after it passes through the focusing lens and
reflects off the reflection mirror.
External device
Video controller PCB
DC controller PCB
/TOP /VDO0-/VDO7
/LSYNC
/BDI
/SCNON
/LSON
Photosensitive
drum
BD mirror
Cylindrical
lens
Focusing lens
Scanning mirror
Scanner motor
/IMCHR
Laser driver
PCB
M1-M8
Dv2-Dv9 /VDOENB
PWM-IC
Reflecting
mirror
LLCNT
/PRNT
BD PCB
PDIN
Collimator
lens