A3.3 Electrophotographic Process - Oki OF5700 Service Manual

Page: 284
Service Guide OKIFAX 5700/5900
Chapter A Board Descriptions

A3.3 Electrophotographic Process

(1) Electrophotographic process
The electrophotographic process is outlined below.
1 Charging
The surface of the image drum is charged negatively and uniformly by applying the DC voltage to the charge roller.
2 Exposure
Light emitted from the LED head irradiates the negatively charged surface of the image drum. The surface potential
of the irradiated surface attenuates to form the electrostatic latent image corresponding to the image signal.
3 Development and residual toner recovery
The negatively charged toner is brought into contact with the Image drum, adhering to the electrostatic latent image
on the image drum by static electricity. This adhesion causes the electrostatic latent image to change to a visible
image.
At the same time, the residual toner on the image drum is attracted to the developing roller by static electricity.
4 Transfer
When paper is placed over the image drum surface, the positive charge which is opposite in polarity to that of the
toner, is applied to the reverse side by the transfer roller. The toner is attracted by the positive charge and is
transferred onto the paper. This results in the transfer of the toner image formed on the image drum onto the paper.
5 Cleaning
The cleaning roller temporarily attracts the residual toner on the transferred image drum with static electricity, then
returns the toner to the image drum.
6 Fusing
The transferred unfused toner image is fused to a sheet of paper by applying heat and pressure to the image.
An electrophotographic process timing chart is shown in Figure 2-5.