Ricoh G147 - Auto Power Control (Apc)

SM 6-13 G147
Detailed
Descriptions
the F-theta mirror, mirror, and BTL (barrel toroidal lens). Then these laser beams go to the
drum through the toner shield glass. The laser synchronization detector determines the
main scan starting position.
 The front door and upper right door (transfer door) are equipped with safety
switches that automatically shut down the laser unit when either door is opened.
6.4.2 AUTO POWER CONTROL (APC)
The LD driver on the LDDR drives the laser diode. Even if a constant electric current is
applied to the laser diode, the intensity of the output light changes with the temperature. The
intensity of the output decreases as the temperature increases.
In order to keep the output level constant, the LDDR monitors the electrical current passing
through the photodiode (PD). Then it increases or decreases the current to the laser diode
as necessary, comparing it with the reference level. This auto power control is done just after
the machine is turned on and during printing while the laser diode is active.
The reference levels are adjusted on the production line. Do not touch the variable resistors
on the LDDR in the field.
6.4.3 DUAL-BEAM WRITING
This LD unit employs two laser diodes [A] (LD) and [B] (L2). Each face of the polygon mirror
writes two main scan lines, and twelve main scans are produced when the polygon mirror
rotates once. This reduces polygon motor rotation speed, reduces noise generated by the
polygon motor, and reduces the frequency of the image data clock.
The two laser beams follow the path: collimating lenses [C] > prism [D] >polygon mirror [E].