Ricoh G148, Service Manual

Page: 442 / 537

Print Process Overview
1. DRUM CHARGE
In the dark, the charge corona unit gives a negative charge to the OPC drum. The grid plate ensures
that corona charge is applied uniformly. The charge remains on the surface of the drum because the
OPC layer has a high electrical resistance in the dark.
2. LASER EXPOSURE
The image from the printer driver is transferred to the drum by four laser beams, which form an
electrostatic latent image on the drum surface. The amount of charge remaining as a latent image on
the drum depends on the laser beam pulse duration, which is controlled by the BICU.
3. DRUM POTENTIAL SENSOR
The drum potential sensor detects the change in drum potential, caused by variable conditions around
the drum (heat, humidity, drum service) and adjusts the following voltages:
• Grid bias voltage (Vg or Vgrid)
• Laser diode power
• Development bias voltage (Vb)
4. DEVELOPMENT
Print Process Overview
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