Auto Power Control (Apc) - Ricoh B121 Service Manual

LASER EXPOSURE

6.6.2 AUTO POWER CONTROL (APC)

+5VLD
1
M61880
LD PD
XLDENB
LD
Video Data
(1 bit)
PD
APC_SH
+5VLD
XDETP
Sync
Detector
GND
LD Drive Board
B121D935.WMF
The LD driver IC drives the laser diode. To prevent the intensity of the laser beam
from changing because of the temperature, the machine monitors the current
passing through the laser diode (LD). The machine adjusts the current to the laser
diode by comparing it with the reference level from the reference circuit.
This auto power control is done just after the machine is turned on and during
printing.
The laser diode power is adjusted on the production line.
NOTE: Do not touch the variable resistors on the LD unit in the field.
B121 Series/B259 Series 6-30 SM