Panasonic KX-FLB758RU Service Manual page 192

KX-FLB758RU
7.9.11. TONER SENSOR.... "TONER EMPTY", "TONER LOW", "CHANGE DRUM"
The Sensor detects whether or not the Developer unit and the toner are present.
When there is not Development unit, the shelter plate let the sensor light passing through, the photo-transistor turns ON, and
the input signal of IC610-128 pin (Digital P.C.B) becomes a low level over 9s. When the Developer unit is set, the shelter plate
move with rotation of development roller, so the photo-transistor turns ON/OFF. If the time of IC610-128 pin´s high level is under
600ms, there is enough toner in Developer unit, if not, toner is near empty.
Toner Sensor
The rest of toner is detected by the move speed of the magnet put on the pendulum of Mixing Paddle. The pendulum is pushed
up by the Mixing Paddle, then it falls down by its own weight. The rotation speed of paddle is set slower than the one of
pendulum which falls down by its own weight. When the toner is still left, the pendulum falls and stops on the toner, then pushed
by the paddle, it starts to rotate. When no toner is left, the pendulum falls to the bottom. Consequently the contact time between
the magnet and steel becomes short when toner is left and long with no toner.
State Photo-transistor
Toner Set (full) OFF time = about 0.3s
Near Empty Toner OFF time>0.6s
No DEV Unit
("CHANGE DRUM")
Signal (IC610-128pin)
High level = about 0.3s
High level>0.6s
ON Low level fix
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