Each tray has four paper height sensors. The illustration below shows the paper height sensors in the 1st tray. This arrangement is duplicated in the 2nd and 3rd trays.

The amount of paper remaining in the tray is detected by the three paper height photo-interrupter sensors on the left rail as the bottom plate rises. Five states, determined by the position of the actuator [A] are possible.

  1. With the actuator [A] below paper height sensor 4 [B], no sensor is actuated and the display indicates 100%.
  2. When the actuator passes paper height sensor 4 [B] , the display indicates 75% of the paper supply remaining.
  3. When the actuator passes paper height sensor 3 [C], the display indicates 50% of the paper supply remaining.

  4. When the actuator passes paper height sensor 2 [D], the display indicates 25% of the paper supply remaining.

    • When the actuator enters the near end sensor [E] and the paper height sensor 2 [D] does not detect the actuator, the machine signals near end.

  5. Finally, when the last sheet feeds, the paper end sensor signals that the tray is empty.

    [A] Paper Height Sensor Actuator

    [B] 1st Paper Height Sensor 4

    [C] 1st Paper Height Sensor 3

    [D] 1st Paper Height Sensor 2

    [E] 1st Paper Height Sensor 1 (Near End)