Paper Size And Volume Sensors - Ricoh FT5540 Service Manual

31 August 1989

6. PAPER SIZE AND VOLUME SENSORS

The CPU sends separate scan pulses (SCAN 3, 4) to the corresponding sensors of the
cassette bank. The output of this group of sensors for all cassettes can be monitored by one
data bus because the scan pulses are sequential, allowing the CPU to determine which
cassette information is being received.
In the above diagram, two example actuator plates are shown. The actuator plates in cassette
3 and cassette 4 paper size sensors in the cassette bank have notches in the fourth and
second positions respectively. Where there are notches, the photointerruptors remain
activated (0 volts). Thus, when scan line 3 is high, bit 4 of the data bus remains LOW; when
scan line 4 is high, bit 2 of the data bus remains LOW. The CPU monitors the data bus at the
appropriate time to determine the paper size in cassettes 3 and 4 of the cassette bank.
Signals from the volume sensors are sent to the copier main PCB through the cassette bank
PCB and the paper feed control PCB; however, the copier operation panel will not indicate
how much paper remains in the cassettes.
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