Canon    LBP3310, Руководство по обслуживанию

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Chapter 2
2-10
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The exposed area on the photosensitive drum is indicated positive in figure despite of the fact that the actual potential on the drum is negative. This means that the
potential of the photosensitive drum is higher than that of the cylinder relative to the potential of the cylinder.
The developing unit is structured by the developing cylinder, which consists the fixed magnet, the developing cylinder rotating around the magnet and the rubber
blade.
The single-component developing material is called toner. The toner is mainly composed of magnetic particles and resin and it is caught onto the cylinder by the
magnetic force. The toner is insulating property and it is charged negative potential by the friction force with the rotating cylinder.
The area of the photosensitive drum, where the laser beam exposed, has higher potential than the toner that is charged negatively on the cylinder. That is, when this
area contacts the toner layer (negatively charged), the toner jumps onto the drum surface by the potential difference between the drum surface and the cylinder
(higher potential on drum side).
This phenomenon is called the projection development and it visualizes the electrostatic latent image on the drum.
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The developing cylinder is applied the AC bias in order to make the toner jump easier onto the drum surface and improve the contrast of the output image.
The central voltage of the AC bias (1600Vp-p) changes according to the developing DC bias.
This printer enables to adjust the image density by changing the potential difference between the cylinder and the photosensitive drum according to changing the
developing DC bias based on the IMAGE DENSITY INFORMATION signal from the video controller.
2.4.1.5 Transfer block
0018-3108
LBP3370 / LBP3310
The transfer block transfers the toner image on the photosensitive drum onto a print paper.
Step 4: Transfer
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The toner on the photosensitive drum surface is transferred onto a paper according to the positive charge from the back side of the paper. The transfer charging
Stirrer
Blade
AC bias
DC bias
Cylinder
Magnet
Photosensitive
drum
Developing cylinder
+V
-V
Voltage (V)
Developing cylinder
surface potential
Drum surface potential
(Exposed)
Time (t)
DC bias
Drum surface potential
(Unexposed)
Paper
Transfer charging roller
Photo-
sensitive
drum