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PTM 2-31 B070/B071
2.4.2 LASER EXPOSURE MECHANISM
The LD unit consists of two 4-channel LDA’s (Laser Diode Arrays) and two collimating
lenses.
Each LDA produces 4 beams [A]. Each collimating lens [B] is a fixed lens, seated in a
V-groove and held in place by a spring and a screw.
Four beams from each LDA [C] pass through the collimating lenses, though the
apertures [D], then strike the polygonal mirror. Due to this multi-beam writing, the
polygonal mirror motor speed can be reduced, thus the noise generated by the
polygon mirror motor and the wear on the motor can be reduced.
Auto Power Control (APC)
A built-in photo diode detects the light emitted from the LD unit. When the photo diode
detects this light, it generates a signal and the feedback of this signal to the LD control
board is used to adjust the strength and amount of light in the laser beams.
NOTE: The laser diode array is assembled and adjusted in the factory, and does
not require physical position adjustment in the field.
LD drivers control the power output from the laser diodes.
(
Digital Processes > Printing > Laser Printing > Laser Diode Power Control)
NOTE: The reference levels are adjusted on the production line. Never touch the
variable resistors on the LD unit.
B070D102.WMF
[A]
[B]
[D]
[C]