Oki OF5300, Руководство по обслуживанию

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Page: 266
Service Manual for OF5300/5600
Chapter B Print Operation Description
3) Exposure
Light emitted from the LED head irradiates the image drum surface with negative charges. The surface
potential of the irradiated part of the image drum drops, thereby forming an electrostatic latent image
associated with the image signal.
The image drum is coated with an underlayer (UL), a carrier generation layer (CGL), and carrier transfer
layer (CTL) on the aluminum base. The organic photo conductor layer (OPC), comprising a CTL and a
CGL, is about 20 mm thick.
The image drum surface is charged to about -750 V by the contact charge of the charge roller.
When light from the LED head irradiates the image drum surface, the light energy generates positive and
negative carriers in the CGL. The positive carriers are moved to the CTL by an electrical field acting on the
image drum. Likewise, the negative carriers flow into the aluminum layer (ground).
The positive carriers moved to the CTL combine with the negative charges on the image drum surface
accumulated by the contact charge of the charge roller, lowering the potential on the image drum surface.
The resultant drop in the potential of the irradiated part of the image drum surface forms an electrostatic
latent image on it. The irradiated part of the image drum surface is kept at about -100 V.