OKIDATA OKIPAGE 20, Service Manual

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Service Manual - OKIPAGE20
Chapter 2 Operation Description
The electro-photographic processing is outlined below. Figure 2-5 shows the electro-photographic printing
process.
(1) Charging
The surface of the image drum is uniformly charged with negative charges by applying a negative 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 part of the image drum surface is lowered, so that an electrostatic latent image
associated with the print image is formed.
(3) Developing and toner recovery
When the negatively charged toner is brought into contact with the image drum, it is attracted to the
electrostatic latent image by static electricity, making the image visible. 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 and a positive charge, opposite in polarity to the toner,
is applied to the reverse side of the paper from the transfer roller, the toner is attracted by the positive
charge and is transferred to the paper. As a result, the toner image formed on the image drum is
transferred to the paper.
(5) Temporary cleaning
Residual toner that remains on the image drum without being transferred is made uniform
by the cleaning roller and is temporarily attracted to the cleaning roller by static electricity.
(6) Fusing
The toner image transferred to the paper is fused under heat and pressure. Figure 2-6 shows an
electro-photographic process timing chart.