Canon Color iR C3480, Service Manual

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Chapter 6
6-7
F-6-7
[1] Print command
[2] Internal timer
[3] Video signal for a single page
6.2.1.4 BD Correction
0014-0763
Color iR C3380G / Color iR C2880G / Color iR C3380i / Color iR C3380 / Color iR C2880i / Color iR C2880 / iR C3480 / iR C3480i / iR C3080 / iR C3080i / iR
C2550
The polygon mirror used in the machine's laser scanner has resulted in imperceptible manufacturing variation of its mirror surface angle. In other words, the ma-
chine, which determines the start points of 4 main scanning lines using the Bk laser as the reference BD, is inherently subject to variation in the starting points of
Y and M main scanning lines.
To make up for the variation, the machine computes the variation among the angles of individual mirrors by measuring BD intervals, correcting the start points of
the Y and M main scanning lines based on the result of the computation.
The machine executes this correction each time it is turned on or for each print job.
[2]
VDO C
VDO Bk
VDO M
VDO Y
Bk TOP
C TOP
M TOP
Y TOP
P TOP
[3]
[1]
[3]
[3]
[3]