Operation; Image Writing; Write Control - Konica Minolta 7145 Service Manual

WRITE UNIT
2.2

Operation

2.2.1

Image writing

The image data from the CCD sensor is converted into digital form by the ADB (A/D conversion board),
and its image processing is then carried out on the SCB (System control board). Based on the processed
image data, the image is written onto the drum by the laser beam output from the LDB (LD drive board).
2.2.2

Write control

A. Dot diameter adjustment
The sensor on the toner control sensor board detects the patch image density on the drum, and the
LDB (LD drive board) controls the quantity of laser beam so that its output value becomes the speci-
fied value.
(1) Timing for execution
a. While in copying
• Executed once for every 20 copies added up. However, when 20 copies are added up in the middle of
the job, the execution is made at the time of completion of the job.
b. Anytime other than while in copying
• While in the L inspection
• When the drum counter is reset
• When the sub power is turned on. However, this is subject to the settings 6 and 7 of the DIPSW16 in
the 25 mode.
B. APC (Automatic power control)
The LDB (LD drive board) monitors the laser output value for every one scan, and maintains the laser
beam quantity at the fixed level by driving the laser so that it becomes the output value set for the dot
diameter adjustment.
C. Write timing
The SCB (System control board) uses a laser detection signal from the INDEX (Index sensor board) to
determine the starting point for laser writing for every one scan in the drum shaft direction.
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