Canon Color imageRUNNER LBP5280 Service Manual Download Page 30

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Technical Reference > Image Formation System > Image Stabilization Control > Color displacement correction control

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Color displacement correction control

This control is to correct the color displacement that appears due to the variation of laser
scanner unit or toner cartridge.
The following objects are controlled by this color displacement correction.
•  Write start position in main scanning direction
•  Magnification in main scanning direction
•  Write start position in sub scanning direction

When one of the following conditions is met, DC controller PCB controls the color
displacement/density sensor and displacement sensor.

The conditions and timing for executing color displacement correction control are shown
below.

Conditions for execution

Execution timing

At power-on

When shifting to idle state
(*5, *2)

When recovering from deep sleep after 8 hours or more have
passed

When shifting to idle state
(*5, *2)

When the door is closed after replacing the Toner Cartridge

Immediately (right after
replacement)

After every 150 pages of printing since the execution of the last
color displacement correction
(However, the count of the number of printed pages is reset when
the power is turned OFF or the machine enters deep sleep, and
the count starts again when color displacement correction has
been executed after that.)

When shifting to idle state
(*2)

When 1 hour has passed since the execution of the first printing
after power ON or the execution of the first color displacement
correction, whichever is earlier, or when 4 hours have passed
since the execution of the last color displacement correction.
(However, the count of the elapsed time is reset when the power is
turned OFF or the machine enters deep sleep, and the count starts
again when color displacement correction has been executed after
that.)

When shifting to idle state
(*2, *3)

When the environment (temperature and humidity) has changed
by a specified value or more

When shifting to idle state
(*2)

Conditions for execution

Execution timing

When requested by the user

After completion of the
jobs in wait
(*4)

*2: Executed immediately after the machine has completed all the jobs to be executed after
the execution conditions have been achieved. (In some cases, density control is executed
after a job received after achievement of the execution conditions has been completed.)
*3: When the machine is in panel off mode, density control is executed when the execution
conditions have been achieved. Density control is not executed during deep sleep. However,
if the execution conditions are satisfied when recovering from deep sleep mode, density
control is executed when shifting to idle state.
*4: When the execution conditions have been achieved, density control is executed
immediately after the machine has completed all the jobs to be executed (before executing
jobs received after the execution conditions have been achieved).
*5: This item is used to control the execution timing by executing the following setting: Setup
> User Maintenance > First Calibration > Color Mismatch Corr. There are 2 types of execution
timing.
After Jobs: Executed when shifting to idle state (immediately after the machine has completed
all the jobs to be executed)
(Default)
Immediately: Executed during initialization of the engine
The following is the sequences of this control.
1) DC controller calculates the degree of each color displacement by the color displacement

detection pattern made on ITB and sends the color displacement information to main
controller.

2) Main controller controls the each color video signal according the color displacement data

and adjusts the write start position in main scanning direction, the magnification in main
scanning direction and the write start position in sub scanning direction.

At printer engine side, DC controller PCB also controls the scanner motor speed to correct
the color displacement in sub scanning direction.