Canon imageCLASS MF8450c, Service Manual

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Chapter 7
7-22
7.4.4 Transfer Roller Engagement/disengagement Control
0019-8979
imageCLASS MF9170c / imageCLASS MF9150c / imageCLASS MF8450c
Overview
In the machine, the transfer roller is engaged with or disengaged from the photosensitive drum via the ETB to reduce the color photosensitive drum consumption
at monochrome printing.
The transfer roller engagement/disengagement control is executed at the following timing.
- Multiple initial rotations at power-on
- Multiple initial rotations at door closing
- Image stabilization control
- Printing operation
The status of engagement/disengagement during printing operation differs depending on the printing mode (monochrome or color mode).
This control works with the developing cylinder engagement/disengagement operation.
T-7-4
*: Thick paper, envelope, rough paper, small-size paper, thin paper (H/H environment), thin paper (when thin paper/rough paper is specified in the
special control mode)
Color mode Transfer roller Developing cylinder
Color printing All color cylinders are engaged. All color cylinders are engaged.
Monochrome printing Plain paper, Transparency Only the black color cylinder is engaged. Only the black color cylinder is engaged.
Others* All color cylinders are engaged.
Power-off/standby All color cylinders are disengaged. All color cylinders are disengaged.
MEMO:
- The photosensitive drum consumption is affected by the drum rotation time.
At monochrome printing of plain paper or transparency, the photosensitive drums of Y, M, and C are disengaged from the ETB so that they do not rotate. In this
condition, the sheet is attracted to the ETB by an attraction bias and fed to the black color photosensitive drum.
However, when feeding thick paper and envelopes, the photosensitive drums of Y, M, and C are engaged with the ETB because the absorption power by the
attraction bias is weak for such media.
- This control is executed every time the printing mode is switched. When mixed printing of color and monochrome is performed, the print speed is reduced due to
engagement/disengagement of the transfer roller.
Service mode:
To prevent reduction of the print speed at mixed printing of color and monochrome, set the transfer roller to color mode (in which all color transfer rollers are engaged
with the photosensitive drum).
COPIER> FUNCTION> SPLMAN> SPL53649
However, when this setting is made, the color photosensitive drum is consumed even at the time of monochrome printing.