Toner Overflow Sensor Circuit - Ricoh FT4430 Service Manual

16 April '88

TONER OVERFLOW SENSOR CIRCUIT

The toner overflow sensor [S14] signals the CPU when the toner collection
bottle is full.
A tiny tuning fork is
This tuning fork is a damping element in
there is nothing in contact with the tuning fork, the vibrating frequency of the
circuit stays low and the transistor stays off.
When toner presses against the tuning fork, the resistance of the piezoelectric
elements that are in contact with the tuning fork changes and the vibrating
frequency increases. The frequency detection circuit passes the higher
frequency signal to the rectifier which activates the switching transistor. The
transistor sends a LOW signal to CN206-AI 5.
When the CPU detects this LOW signal, it stops the copier,
Toner Bottle indicator, and blinks the Service Call indicator.
used as
the sensing element of the toner overflow sensor.
a
multivibrator circuit. As long as
2-56
lights the Used