Canon imageRUNNER ADVANCE C5255, Service Manual, Page: 77 / 1443

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Technology > Laser Exposure System > Various Controls > BD correction control
Technology > Laser Exposure System > Various Controls > BD correction control
■
BD correction control
● Purpose
This is to correct the displacement of writing start position of each color laser due to the angle
variation of scanner mirror facet.
●
Execution timing
At power-ON, per printing
●
Execution time
Within approx. 0.5s or less
●
Control detail
1) DC Controller measures the BD interval after the constant-speed rotation control of
Scanner Motor is completed.
2) DC Controller calculates the correction value according to the gap of BD interval.
3) Based on the foregoing correction value, image writing position is corrected.
BD1 BD2 BD3 BD4
BD1 BD2
α
α
BD3 BD4
BD1 BD2 BD3 BD4
VDO VDO VDO VDO
START
END
Scanner motor
control finish
(Constant-speed
rotation detection)
BD interval
measurement
Writing start correction
value calculation
Writing start position
correction
Narrow interval
Constant interval
Constant interval
Constant interval
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