Bd Correction - Canon iR C3380 series Service Manual

Bk TOP
VDO M
VDO Bk
[1] Print command
[2] Internal timer
[3] Video signal for a single page

6.2.1.4 BD Correction

/ / / / iR C3380i / iR C3380 / iR C2880i / iR C2880
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.
[1]
[2]
P TOP
Y TOP
M TOP
C TOP
[3]
VDO Y
VDO C
[3]
[3]
F-6-7
Chapter 6
[3]
0014-0763
6-7