Canon Color imageRUNNER LBP5280, Service Manual, Page: 31 / 284

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Technical Reference > Image Formation System > Transfer Unit > Pad transfer
Technical Reference > Image Formation System > Transfer Unit > Pad transfer
Note:
This indicates the image size in the main scanning direction.
Since this machine is equipped with the independent photosensitive drum for each
color, the photosensitive drum position differs due to the toner cartridge variation and
that leads to the laser wave length difference. Thus, image range differs depending on
a color in main scanning direction so that the color displacement occurs at the edge of
the image.
Drum Cartridge
■ Developing roller engagement/disengagement control
The developing cylinder engagement/disengagement control engages the required
developing cylinder with the photosensitive drum according to the print mode, full-color mode
or monochrome mode.
The necessary developing cylinder is engaged with the photosensitive drum only when
required, preventing a deterioration of the drums and making maximum use of the life.
The engagement/disengagement of the developing cylinder is controlled by the DC controller
rotating the main motor and changing the direction of the developing disengagement cam.
The DC controller controls the developing cylinder state, whether engaged or disengaged, by
counting the main motor rotation after it detects the signal from the developing homeposition
sensor.
All four colors' developing cylinders disengage from the photosensitive drums when the
printer is turned on and when a print operation is completed. All four colors' developing
cylinders engage with the photosensitive drums when the full-color mode is designated. Only
black's developing cylinder engages with the photosensitive drum when the monochrome
mode is designated.
The DC controller determines an abnormality of the developing cylinder engagement/
disengagement function and notifies the main controller when it does not sense the signal
from the developing homeposition sensor for a specified period during the developing cylinder
engagement/disengagement operation.
Transfer Unit
■
Pad transfer
The printer has a pad transfer method for the primary transfer operation.
The pad transfer method stabilizes an image compared to the conventional separation roller
method. The features for the pad transfer method are as follows:
The wider nip width between the transfer pad and the photosensitive drum improves the
transfer performance.
Narrow nip
width
<Pad transfer method> <Roller transfer method>
Wider nip
width
ITB
Photosensitive Drum
Transfer Pad Transfer Roller
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