Optics; Overview - Ricoh A156 Service Manual

4. OPTICS

4.1 OVERVIEW

The optics unit reflects an image of the original on the exposure glass onto
the OPC drum. This forms a latent electrical image of the original.
In this model, a halogen lamp is used for the exposure lamp [A]. The lamp
surface is frosted to ensure even exposure. The specifications of the lamp
are as follows. Note that the A153/155/156 models are faster, so they need
more light during exposure.
A153/A155/A156
A157/A159/A160
Six mirrors are used to make the optics unit smaller and obtain a wide
reproduction ratio range (50 ~ 200%).
The lens [B] is driven by two stepper motors for (1) vertical movement
(parallel to the paper feed direction) and (2) horizontal movement. Also, to
correct for focal length change in reduction and enlargement modes, the
third scanner unit [C] (4th and 5th mirrors) is moved (3) vertically (parallel to
the paper feed direction) by another stepper motor.
A toner shield glass [D] and a green filter [E] are installed above the OPC
drum to improve reproduction of red images or text.
STM
[A]
[D]
115V Machines
97V 280W
97V 200W
[B]
[C]
(2)
(3)
(1)
(1)
(2)
2-39
[B]
230V Machines
85V 280W
85V 200W
(3)
Rev. 7/95
[C]
[E]
A156/A160/A162