Ricoh C231 Service Manual page 449

6.6.6 DETECTION OF MASTERS ON THE DRUM
[A]: Drum master sensor
[B]: Black patch on the screen
[C]: Black patch on the clamper
The drum master sensor [A] detects whether there is a master on the drum.
When there is a master on the drum, the black patch [B] is covered and the
sensor detects the light reflected from the master. When there is no master on
the drum, the black patch [B] is exposed. The black patch does not reflect light
back to the sensor. Because of this, the master eject process can be skipped
when a new master is being made, if no master is detected on the drum.
The drum master sensor uses the black patch [C] on the clamper for jam
detection. ( 6.10.3)
SM 6-27
DRUM
[C]
[B]
[A]
C238D028.WMF
C231/C237/C238