Canon imageCLASS MF8450c, Service Manual

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Chapter 7
7-7
7.2 Image Stabilization Control
7.2.1 Overview
0019-5019
imageCLASS MF9170c / imageCLASS MF9150c / imageCLASS MF8450c
The quality of a printed image is affected by changes in environmental condition where the machine is installed or changes in the characteristics of the photosensitive
drum and toner.
The machine performs the following controls according to necessity to stabilize print operation.
- Environmental change corrective control
To correct values of primary charging biases and developing biases based on the result of detection performed by the environment sensor. This is comparable
to a conventional D-max control.
- D-half control
To correct the gradation data in the main controller PCB based on the result of detection performed by the color displacement/density sensor
- Color displacement corrective control
To correct the timing of sending a video signal based on the result of detection performed by the color displacement/density sensor.
- Auto gradation correction control
To make a stable gradation density feature of image, customers need to execute any of full correction, quick correction or copy image correction.
Timing of execution of each control
T-7-1
*: Executed when 120 sheets are printed after the initial implementation
Executed when 500 sheets are printed after the 2nd implementation
Executed when 1000 sheets are printed after the 3rd implementation
Executed when 1000 sheets are printed thereafter
No. Execution timing Operation time
Environmental
change corrective
control
D-half control
Color
displacement
corrective control
Remarks
1
Replacement of the
cartridge
Approx. 3 min Yes Yes Yes
Executed at the time of multiple initial rotations after power-
on or door closing
2 Environmental change Approx. 2.5 min Yes Yes - Temperature and humidity by the environment sensor
3
After a specified period
of time is passed
Approx. 2.5 min Yes Yes -
Executed 8 hours after the drum motor stops. The control is
not however executed during sleep mode.
4
Recovery from sleep
mode
Approx. 2.5 min Yes Yes - Executed 8 hours after the drum motor stops.
5
After a specified
number of sheets is
printed
Approx. 3 min Yes * Yes *
Yes
(Every 1000
prints)
Executed after a job is completed.
6
Full correction
(PASCAL)
Approx. 5 min Yes Yes - Executed by user's operation.
7 Quick correction Approx. 2.5 min Yes Yes - Executed by user's operation.
8 Copy image correction Approx. 4 min Yes Yes - Executed by user's operation.