Charging Process; Exposing Process - Brother MFC8500 Service Manual

(1) Charging process

The high-voltage power supply applies DC bias to the corona wire to generate ion on the grid. The
ion uniformly charges the surface of the laser-sensitive drum to approx. 870V which is kept by the
voltage regulator grounding the grid to the frame.

(2) Exposing process

When the laser-sensitive drum holds a positive electrical charge, the laser beam issued from the
laser unit scans the drum according to the print image to expose the drum surface for neutralizing
the spots where black should be, forming an electrostatic latent image.
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