Color Displacement Correction Control - Canon iR C3380 series Service Manual

Chapter 7

7.3.9 Color Displacement Correction Control

/ / / / iR C3380i / iR C3380 / iR C2880i / iR C2880
The machine performs the following 3 types of control to correct displacement of color possibly caused by differences among components of its laser scanner unit
and drum unit:
- main scanning write start correction
- sub scanning write start correction
- main scanning magnification correction control
The DC controller forms patterns for detection of color displacement for individual colors, and uses the color displacement sensor to detect the position of the pat-
terns.
The DC controller computes the degree of displacement with reference to the position of the pattern detected; based on the result, the DC controller or the main
controller corrects the displacement for individual colors.
7-22
INT
40
20
SIN
10 40
Data output(D-CON)
Current gradation
100
characteristics
60
Gradation characteristics
after correction
40
20
40
Data output(V-CON)
Start-up
DC controller
Patch pattern formation
UN16
Patch reading
DC controller
Measurement data (SIN) transmission
Main controller
Comparison of measurement data (SIN)
and reference data (INT)
Main controller
Offset value (alpha) determination
(i.e., difference between SIN and INT)
Main controller
Inclusion of result in
D-half correction table
F-7-29
0013-8493