AM-400 (serv.man7). Chapter 3 (Mechanical Description). - Sharp Copying Equipment Service Manual (repair manual). Page 13

AM-400DE

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The main charger is a rotating brush roller.

The main charger removes residual toner from the OPC drum by its
rotating sweeping action and causes it to stick to the brush.

At the same time, a high voltage of -950V is applied to the main
charger roller to generate a discharge of electricity between the roller
and the OPC drum, generating positive and negative charges. The
negative charges are attracted to the OPC drum, and evenly distrib-
uted on the OPC drum. (The OPC drum surface is evenly charged.)

Positive and negative charges are generated in the OPC drum CGL
exposed with the laser beam.

Positive charges generated in the CGL are attracted toward the OPC
drum surface (negative charges), and negative charges toward the
aluminum layer (positive charges).

Therefore, the positive and negative charges neutralize each other in
the laser-exposed area of the OPC drum surface and the aluminum
layer, decreasing the potential of the OPC drum surface.

The area which is not exposed to laser beam has no change, and the
OPC drum surface remains negatively charged to keep a high poten-
tial. As a result, latent electrostatic images are formed on the OPC
drum.

Residual toner the OPC drum is 
stirred and negative charges are 
scattered evenly on the OPC 
drum. (The OPC drum surface is 
evenly charged.)

AC760V
(P-P)

DC-950V

Main
charger
brush

Residual
toner

CTL

CGL

OPC drum

Aluminum layer (drum base)

STEP 2 (Exposure): Laser beam scanning light corresponding to 

the print data is radiated on the OPC drum.

CTL

CGL

CTL

CGL

Non-exposed area

Laser beam

Exposed area

Aluminum layer
(Drum base)

Aluminum layer
(Drum base)