e-STUDIO160/200/250 DEVELOPER SECTION 12 - 6 December 2002 TOSHIBA TEC
12.5 Toner Control Circuit
12.5.1 Outline
The amount of toner remaining in the process unit is detected by the piezoelectric type toner empty
sensor. When the amount is small, the toner supply motor is driven to rotate the auger in the toner
cartridge, causing the toner to be supplied to the process unit.
12.5.2 Toner empty detection circuit
The circuit for detecting the amount of toner remaining in the process unit consists of the following:
1) The I/O port GA-1 (IC7) turns the TONEREN signal (toner detection start signal) to “High” level to turn
on Q1. This allows a +5V power supply to be delivered to the TES driver (IC3).
↓
2) The TES driver sends the TES signal (drive/detection signal) to the toner empty sensor.
↓
3) The toner empty sensor performs oscillation by the TES signal. At this time, if there is much toner in
the process unit, the oscillation of the sensor is obstructed due to the pressure of the toner, thus
causing the waveform of the TES signal to change. On the other hand, if there is not much toner in it,
the pressure of the toner decreases to cause the sensor to perform oscillation so that the waveform of
the TES signal almost remains unchanged.
↓
4) The TES driver detects a change in phase of the TES signal, and judges that there is no toner when a
change in phase is small. At this time, the TES driver sends the TESMON signal (toner empty signal)
at “Low” level to the I/O port GA-2 (IC6).
↓
5) The CPU (IC66) judges the amount of remaining toner by the number of times the level of the TESMON
signal becomes low.
12-4-01
IC3
TES driver
Main PWA Relay PWA
Toner empty sensor
TES
C425
R493
SG
3
4
9481
2
CN27
CN21
CN15
94
TESMON
TONEREN
563
Q1
+5V
2454
IC2
IC7
I/O port GA-1
IC6
I/O port GA-2
IC66
CPU
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