Ricoh FT8680 Service Manual page 62

DEVELOPMENT
6. DEVELOPMENT
6.1 OVERVIEW
[E]
[G]
This copier uses a double roller (diameter 20 mm each) development system.
This system differs from single roller development system in that (1) it
develops the image in a narrow area and (2) it develops the image twice.
Also, fine toner and developer (smaller particle size) are used. As a result,
the image quality, especially of thin lines, the trailing edge of half-tone areas,
and black solid areas are improved.
A dc motor is used to drive the development unit.
The developer is supplied to the developer guide [A] upper side by the
paddle roller [B]. The magnet of the upper development roller [C] attracts the
developer to the roller surface.
The doctor blade [D] trims the developer to the desired thickness and creates
back spill to the cross mixing mechanism [E]. The developer is transferred to
the lower development roller [F] and then returned to the agitator roller [G]
area via a paddle roller.
The development rollers are given a positive bias to prevent the toner from
being attracted to the non-image areas, on the drum surface, that may have a
slight residual positive charge. The bias voltage is determined based on the
factors checked by the process control system.
[D]
[A]
[B]
A171D594.img
2-38
31 July 1995
[C]
[F]