Apc (Auto Power Control) - Ricoh MP 7503SP Field Service Manual

5. Detailed Descriptions
No. Name
4 Collimating Lens

APC (Auto Power Control)

A built-in PD (Photo Diode) detects the light emitted by the LD (Laser Diode). When the PD detects the
light emitted from the LD, the PD sends an output signal to the LD control board, and then the feedback
from this signal is used to fix the standard value for the strength of the laser. The LD unit is also non-
adjustable so there are no LD power adjustments required after the LD unit has been replaced.
LD Safety Switch (Front Door Interlock Switch)
The front door is provided with a single interlock switch that disables the laser unit when the front door is
opened. When the interlock switch opens, this cuts the 5V circuit to the LDB and disables it.
Laser Unit Control
The 600 dpi 10-bit scan data is converted to either 1200 dpi, 1- bit digital data, or 600 dpi/1-bit
digitized data in the IPU on the BICU and then input to the laser control module of the ASIC. The
converted data is then digitized through 35 levels of Pulse Width Modulation (PWM) to determine the
strength of light exposure.
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