Scanner Motor Control - Ricoh FT5540 Service Manual

3.4 SCANNER MOTOR CONTROL

The scanner drive motor is a dc servomotor. The CPU on the optics board controls the speed
of this servomotor. The main CPU and the optics CPU communicate through a serial interface
bus (TXD/RXD).
After the main CPU sends the scanner start signal to the optics CPU, the optics CPU receives
the drum speed data from the main PCB (pulse generator).
An encoder on the servomotor has two magnetic sensors that generate two pulse signals.
The optics CPU monitors the scanner speed and direction by these pulse signals.
Based on the drum speed and encoder data, the optics CPU determines the proper speed for
the scanner drive motor to obtain proper vertical magnification. The optics CPU sends the
speed data to the timer IC, which controls the scanner motor circuit.
The home position sensor informs the optics board when the first scanner is in the home
position.
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31 August 1989