Canon fax basic 2000 サービスマニュアル

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RECORDING SECTION

• Developing step

The developing cylinder comprises a magnet and sleeve. First, the toner is

charged to have a negative electrical charge by the friction between with

the rotating developing cylinder. The toner is then attracted by the magnet

to be held in contact on the sleeve. The toner on the sleeve is regulated by

the blade to form a uniform layer of toner on the surface of the sleeve. The

potential of the AC bias previously applied to the developing cylinder

changes, and toner jumps to the electrostatic latent image section on the

surface of the photosensitive drum when the electromagnetic field between

the surface of the developing cylinder and the electrostatic latent image

section on the surface of the photosensitive drum becomes stronger than

the force of the magnetic that is attracting the toner. This development is

called the “toner projection development.”

Fig. 4-49   Development

DC bias is also applied to the developing cylinder in addition to the AC

bias. This DC bias is the center of the amplitude of the AC bias voltage.

Accordingly, the peak of the AC bias voltage changes by varying the DC

bias. The AC and DC biases adjust the amount that the toner jumps and

works to improve the contrast of the image.

Next, let’s explain the function of toner during development.

AC bias

DC bias

Blade

Toner

Magnet

Sleeve

Developing
cylinder

Photosensitive

drum