LASER EXPOSURE 22 March 1996
6.2.5 Laser Synchronizing Detector Boards
[A]
[B]
A133D613-3.wmf
Some of the optical components are made of plastic, and may expand and
contract with changes of temperature. If this happens, the number of pulses
in the laser main scan across the drum will vary. To counteract the effects of
this, the machine adjusts the frequency of the laser pulses to keep the
number of laser pulses in each main scan constant.
To do this, the machine has two laser synchronizing detector boards. They
are used to determine the number of clock pulses between the start and end
of each main scan. (These clock pulses are from the base clock, which is at a
much higher frequency than the laser frequency.)
The laser synchronizing detector board-1 [B] synchronizes the main scan
start timing. At the other side, the laser synchronizing detector board-2 [A]
counts the number of clock pulses since detector board-1 was activated; from
this count and from the current laser frequency, the machine can calculate
how many laser pulses there were across the main scan.
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ACEC
RICOH
