Ricoh A318 Service Manual page 19

ORIGINAL FEED
7.7 BELT DRIVE MOTOR CIRCUIT
DF Main Board (PCB 1)
Speed
Data
ON/OFF
CPU
Forward/
Reverse
A dc servomotor is used as the belt drive motor. The driver IC controls the
speed of the belt drive motor. The CPU sends the speed data (programmed)
to the driver IC. The driver IC sends the pulse-width-modulation (PWM)
signal to the driver circuit, which sends the motor drive pulses.
An encoder in the servomotor has two magnetic sensors that generate two
pulse signals (phase A and B). The driver IC monitors the belt speed and
direction with these pulse signals and uses the signals to regulate the motor's
speed.
PWM
Driver
Driver
Circuit
IC
+5V
Phase A
Phase B
18
CN102-1
CN102-2
CN103-1
CN103-2
CN103-3
CN103-4
1 May 1993
Belt Drive
Motor
Encoder