Ricoh FT5540 Service Manual page 124

31 August 1989
Paper End Detection
After the last sheet of paper is fed from a cassette, the Add Paper indicator lights. The first and
second paper end sensors use photointerruptors. When a sensor is actuated, the
photointerrupter turns off (0 volts to 5 volts). The CPU detects paper end by monitoring the
output of these sensors. The CPU uses scan pulses to monitor the output of these sensors
and detect paper end.
[A] Manual feed paper end sensor
[B] Cassette paper end sensor
The first paper end sensor consists of two photointerrupters, which are in parallel. The CPU
detects a paper end condition by monitoring these two photointerrupters and the manual feed
sensor.
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