Ricoh FT4460, Service Manual, Page: 82 / 413

28 February 1989
5. DEVELOPMENT
5.1 OVERVIEW
The development section is composed of a black development unit [A] and a
color development unit [B]. Normally, the black development roller is in con-
tact with the drum [C]. When color copy mode is selected, the color develop-
ment unit moves against the drum and the black development unit is pulled
back.
Both development units have a development roller [D], two paddle rollers [E],
atoner supply roller [F] and a toner hopper [G].
The paddle rollers pick up developer in their paddles and transport it to the
development roller. Internal permanent magnets in the development roller at-
tract the developer to the development roller sleeve.
The turning sleeve of the development roller then carries the developer past
the doctor blade. The doctor blade trims the developer to the desired thick-
ness and creates a backspill for the cross-mixing mechanism.
The development roller continues to turn, carrying the developer to the drum.
When the developer brush contacts the drum surface, the negatively charged
areas of the drum surface attract and hold the positively charged toner. In this
way, the latent image is developed.
Negative bias is applied to the development roller to prevent toner from being
attracted to non-image areas on the drum that may have a residual negative
charge. Negative bias also controls image density.
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