Ricoh FT5233 Service Manual page 59

OPTICS 12 February 1992
4.5 ORIGINAL SIZE DETECTION
[B]
[A]
[C]
[D]
There are six (for LT version) or seven (for A4 version) reflective sensors in
the optics cavity for the original size detection. Two of them [A] are used for
sensing the original width and the other four/five [B] are for the original length.
While the main switch is on, these sensors are active and the original size
data is always sent to the main CPU. You can recognize this by the changes
of the original size indicator when moving an original on the exposure glass.
However, the CPU checks the data only twice in platen mode for determining
the original size for actual copying in APS or AMS modes.
First check is done when the platen (or DF) position sensor [C] is activated.
At this time the angle between the platen cover and the exposure glass is
about 30 degrees. Only the sensor(s) underneath the original receive the
reflective light and output a low signal. The other sensor(s) output a high
signal. The CPU sends an original size signal to the operation panel board
and stores this data.
A second check is done when the platen cover (or DF) is closed and the
platen cover switch [D] turns on. The CPU compares the second check with
the first one to confirm if the detected original size is correct or not.
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