Ricoh FW830, Руководство по обслуживанию

Страница: 53 / 227

6.3 TONER OVERFLOW SENSOR
The toner overflow sensor [A] signals the CPU when the toner collection
bottle is full.
A small tuning fork [B] is used as the sensing element of the toner overflow
sensor. This tuning fork is a damping element in a multivibrator circuit. As
long as 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 CN107-B22.
When the CPU detects this LOW signal, it stops the copier and lights the
Toner Collection Bottle indicator.
[B]
[A]
+5 (Vc)
OSC
Freq.
Detec-
Rectifier
Tr.
CN107
-B22
Toner Overflow Sensor
Main Board
tion
0/5 0
1
2
3
CLEANING 31 December 1992
2-34