Canon imageRUNNER ADVANCE C5255 Series Service Manual page 77

2
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.
2 Technology > Laser Exposure System > Various Controls > BD correction control
START
Scanner motor
control finish
(Constant-speed
rotation detection)
BD interval
measurement
Constant interval
Narrow interval
BD1 BD2
Writing start correction
value calculation
α
BD1 BD2
Writing start position
correction
α
VDO
BD1 BD2
END
2-39
Constant interval
Constant interval
BD3 BD4
BD3 BD4
VDO VDO VDO
BD3 BD4
F-2-56
2-39