Development; Overview - Ricoh FT4430 Service Manual

DEVELOPMENT

Overview

When the main motor
[B] start turning. The
transports it to the development roller. Internal permanent magnets in the
development roller attract the developer to the development roller sleeve.
The turning sleeve of the development roller then carries the developer past
the doctor blade [C]. The doctor blade trims the developer to the desired
thickness and creates backspin to the cross-mixing mechanism.
The development roller continues to turn, carrying the developer to the
selenium drum. When the developer brush contacts the drum surface, the
positively charged areas of the drum surface attract and hold the negatively
charged toner. In this way, the latent image is developed.
Positive bias is applied to the development roller to prevent toner from being
attracted to non-image areas on the drum that may have residual positive
charge. The bias also controls image density.
After turning about 100 degrees more, the development roller releases the
developer to the developer tank. The developer is agitated by the paddle
roller and the cross-mixing mechanism.
Also, in this machine, rotation of the paddle roller [A] and development roller
[B] tend to cause air pressure inside the unit at point [D] to become higher
than the air pressure around the development unit.
Therefore, a hole, fitted with a filter, has been added to the top of the unit to
relieve air pressure and to minimize toner scattering. It also causes air flow
across the face of the ID sensor, which helps dislodge any toner or paper
dust which might fall on it. Also, to allow better heat transmission than earlier
machines, the bottom plate of the unit is made of aluminum.
turns on, the paddle roller [A] and development roller
paddle roller picks up developer in its paddles and
16 April '88