Ricoh Aficio 1027 - Auto Power Control (APC)

LASER EXPOSURE 10 August, 2001
2-22
2.3.2 AUTO POWER CONTROL (APC)
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 while the laser diode is active.
The laser diode power is adjusted on the production line.
NOTE: Do not touch the variable resistors on the LD unit in the field.
LD
Controller
LD Driver
+5V
Reference
Circuit
VIDEO
LD OFF
LD OFF
LD ON
LD LEVEL
VIDEO
Monitor
PD LD
LD Drive Board
LD
VREF
B027D510.WMF