Canon LBP-1210 Service Manual page 118

CHAPTER 2
4. Horizontal sync control
This control determines the writing position in the horizontal direction on an image.
The CPU generates the UNBLANKING signal based on the BD INPUT (/BDI) signal sent from
the BD sensor installed in the laser/scanner unit. During this unblanking period, the CPU con-
trols the LASER CONTROL signals to force the laser diode (LD) to emit.
After detecting the laser beam, the BD sensor generates the BD input (/BDI) signal and sends
it to the CPU in the engine controller. Based on the /BDI signal, the CPU generates the HORI-
ZONTAL SYNC (/BD) signal. When detecting that the picked-up print paper reaches the speci-
fied position, the CPU starts sending the /BD signal to the interface controller. After deceiving
the /BD signal, the interface controller outputs the VIDEO (/VDO, VDO) signals to the laser
driver IC to determine the writing position in the horizontal direction on an image.
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