Ricoh A250 Service Manual page 362

PAPER HEIGHT DETECTION
2.4 PAPER HEIGHT DETECTION
The amount of paper in the tray is detected by the combination of on/off signals
from two paper height sensors [A] and [B].
When the amount of paper decreases, the bottom plate pressure lever [C] moves
the actuator up.
The following combination of sensor signals is sent to the copier.
Amount of Paper Paper Height Sensor 1 Paper Height Sensor 2
Near End
30%
70%
100%
When the tray contains paper of a small width, the paper feed pressure may
become too low when the thickness of the stack of remaining paper has
decreased. The lift motor rotates forward 300 ms after the sensor detects a certain
amount of paper remaining in the tray to increase paper feed pressure, simulating
the pressure generated by a full tray.
The amount of remaining paper depends on SP modes 1-908-6 and 7. The amount
of forward rotation depends on SP1-908-4 and 5. Note that there are two paper
size thresholds: small and middle (this is the same as for the paper lift mechanism
described earlier). Some models only use the small threshold. The paper size
thresholds depend on SP1-908-8 and 9.
A250
[C]
OFF
ON
ON
OFF
10-10
[B]
[A]
A861D107.WMF
ON
ON
OFF
OFF
[C]
SM