exceeds -700 vdc, the varistor shunts this excess voltage to ground.
Exposure
Light emitted from the LED head is radiated to the image drum surface which is charged with
negative ions. The areas of the drum that light is directed to become conductive. This allows the
surface potential in these areas to drop from -700 vdc to approximately -100 vdc, thereby forming
a latent image associated with the image signals.
Developing
The toner supply roller and the development roller are supplied with bias voltages required during
the developing process. -550 vdc is supplied to the toner supply roller, -400 vdc to the
development roller. The toner supply roller is constructed of a porous material which absorbs
toner. Since the development roller charge is more positive than the toner supply roller charge,
toner is attracted from the toner supply roller to the development roller.
The toner attracted to the development roller is scraped off by the doctor blade, forming a thin
coat of toner on the development roller surface.
Since the areas of the drum exposed to light (-100vdc) are charged more positive than the toner
(-400 vdc), the toner is attracted to the exposed areas of the Image drum surface, making the
latent image visible.
Transfer
As paper passes by the image drum surface, a positive charge (+5Kvdc), is applied to the charge
wire causing the paper to be charged positively through corona discharge. Since the paper is
charged more positive than the toner (-100 vdc), the toner is attracted to the paper.
#####
Cleaning
Upon completion of transfer, residual toner on the image drum is scraped off by the cleaning
blade. The residual toner is returned from the toner recovery unit to the developer unit for reuse.
