Operating Principle Of Reflective Photosensors Ppsens1, Ppsens2, Ppsens3 And Pesens - Kyocera AD-63 Service Manual

(2) Operating principle of reflective photosensors PPSENS1, PPSENS2, PPSENS3 and PESENS

LED
PPSENS3
The following is the operating principle of paper path sensor 3 (PPSENS3). Paper path sensors 1 and 2 (PPSENS1,
PPSENS2) and the paper empty sensor (PESENS) operate in the same manner.
A pulsating signal from pin 33 of the CPU IC8 turns Q9 on and off, causing the LED on the sensor PCB to flash. When the
flashing LED light reflects on the paper, the phototransistor turns on and off. The on/off signal is then inverted by IC7.4 and
the paper presence signal (pulse) is input at pin 62 of the CPU IC8.
If there is no paper, the phototransistor remains off and 5 V DC is input at pin 62 of the CPU IC8.
5 V DC
CN6-12
R78
CN6-10
Phototransistor
CN6-11
1
R71
2
SGND
Figure 2-3-3 Reflective photosensor (PPSENS3) circuit
Off
On
C 2
1 1
Q9
B 2
E 3
R15
1
SGND
R12
1 2
1
C25
2
SGND
5 V DC
1
R28
IC6.1
R69
2
2 2 1
Y A
5 V DC 5 V DC
1
R90 R89
2
9
+
14
8
–
1
IC7.4
R88
2
SGND
Off
On
5FF
33
CPU
IC8
1
2
62
2-3-3