Development Bias; Development Bias Mechanism; Correction For Paper Width And Thickness (By-Pass Tray Only) - Ricoh A-P4 Service Manual

6. Details
The outer paddle moves developer to the front Ê and supplies it to the development roller. Developer that
spills off by the doctor blade Ë passes through the holes [C] in the outer paddle, and is transported to the
rear Ì by the inner auger.
While the dual mixing roller is moving the developer, some developer also passes back to the development
unit through the holes in the bottom of the paddle roller Í. New toner from the toner bottle and recycled
toner from the toner collection coil both enter the development unit at [D].

Development Bias

Development Bias Mechanism

Black areas of the latent image are at a low negative charge (about 150 V) and white areas are at a high
negative charge (about –950 V).
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To attract negatively charged toner to the black areas of the latent image on the drum, the high voltage
supply board [A] applies a bias of –540 volts to the development roller throughout the image development
process. The bias is applied to the development roller shaft [B] through the bias terminal spring [C] and
bias terminal [D].
The development bias voltage (–540 V) can be adjusted with SP2201 (Development Bias).

Correction for Paper Width and Thickness (By-pass Tray only)

The by-pass tray can be used for non-standard paper narrow than sizes accepted by the paper trays.
Thicker paper, OHP sheets, etc. can also be loaded in the by-pass tray but adjustments must be performed
with the SP modes listed below in order to avoid jams and misfeeds.
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