Paper Feeding Motor Encoder Sensor Circuit; Registration Sensor Circuit - Epson GT-1200 Service Manual

ADF

2.1.2.4 Paper Feeding Motor Encoder Sensor Circuit

The paper feeding motor is used to manage the following operations:
q Registration operation
q Drives the transportation motor after the timing sensor goes off.
q Controlling backward rotation of the motor
Since this motor is used for various operations, the motor rotation must be
precisely controlled. Failure in controlling the motor does not guarantee
prompt feeding, or may result in jamming caused by the document
inserted over the document remaining in the ADF. The motor rotation is
controlled according to the signal form the photo-interrupter which detects
the slid plate directly attached to the motor shaft. The signal is output to
the CPU via the resistors only.
+5V
R82
180
CN1
+5V
1
2 KM CLK
GND
3
GND
Paper Feeding Motor Encoder Sensor Circuit Block Diagram
Rev. A
TP20
IC12
R61
CPU
10K
R14
74
INTP2
10K
Figure 2-45.

2.1.2.5 Registration Sensor Circuit

The registration sensor with an LED and the photo transistor built in has
an mirror attached across the paper path. Since the registration sensor is
a reflex type sensor, it detects paper empty condition by emitting infrared
light from the LED toward the mirror and receiving the light reflected on
the mirror.
The voltage input to the sensor is divided by R55 and R56, and 1/3 of the
original level is input to the AD converter of the CPU. (Actually, it is
regulated to 5 V by D2.) Analog data for the input voltage is output one
after another in a rectangle waveform from IC4 via PWM circuit in the gate
array. This PWM signal is integrated via R3 and C6 of the C,R circuit and
converted into the analog voltage. Then it is amplified by the non-reverse
amplifier to establish the reference value for the comparator. Therefore,
the reference value is set to 1/3 of the High level of each sensor output
timing. In case the voltage level input to the AD converter of the CPU
drops below 1.6 V, the CPU outputs High from Pin 48 to increase LED
emission.
C44
0.01uF
R39
IC4-18 22K
AGND
IC5
RDDPWM R3
-
+
C6
10K
0.01uF
C40
AGND
0.01uF
AN+24V
TP14
CN1
13 AN+24V
REGS
14
15 RDDLED
R68
2.7 K
R69
5.6 K
AGND
Figure 2-46. Registration Sensor Circuit Block Diagram
Operating Principles
+5V
R38 R23
TP19
22 K 10K
R60
IC6
4.7K
-
+
R56
100K
+5V
10K
AGND
D2
TP23
R65 R4
10K
10K
R55
C16
4.7K
0.1uF
Q4
AGND
IC12
73
INTP1
CPU
56
ANIO
48
P11
2-14