Panasonic KX-FLB852CX Service Manual page 246

KX-FLB852CX / KX-FLB852CXS
7.12.18. TONER SENSOR.... "TONER EMPTY", "TONER LOW", "CHANGE DRUM"
The Sensor detects whether or not the Drum unit and the toner are present.
When there is not Drum unit, Hall IC (IC40) turns off, and the input signal of IC604-95pin (Digital P.C.B) becomes a High level
over 9s. When the Developer unit is set, Hall IC (IC40) turns ON/OFF. If the time of IC604-95pin´s Low 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.
Mixing Paddle does not rotate
State
Toner Set (full)
Near Empty Toner
("CHANGE DRUM")
Display
-
TONER LOW
CHANGE DRUM High level fix or Low level fix
246
Signal (IC604-95pin)
Low level = about 0.3s
Low level>0.6s