Ricoh Di-C1 Manual page 295

Paper Height Detection
Bottom Plate
Pressure Lever
Paper Height
Sensors
Bottom plate pressure lever: Moves as paper is used up
Slide 295
Note that these sensors are not used unless the optional printer controller
has been installed. Then the current status can be viewed from the driver.
Note that this feature is only available for the optional paper tray units.
The two paper height sensors detect the amount of paper in the tray.
The actuator is attached to the bottom plate pressure lever.
The lift motor rotates to increase the feed pressure when the remaining
paper falls below a certain amount.
When the tray contains paper of a small width, the paper feed pressure
may become too low when the thickness of the remaining stack of
paper has decreased. To counteract this, the lift motor rotates forward
for a short while after the remaining paper falls below a certain level.
This increases paper feed pressure, simulating the pressure generated
by a full tray.
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