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[c] Original timing sensor (DTD)
Reverse timing sensor
B3B-PH-K-S
A
1
C
2
VOUT
C
DTD
A
SGND
3
SGND
K
E
GP2S40
The original timing sensor is of the reflection type, and is integrated with the LED and the photo transistor.
Infrared light emitted from the LED is reflected by the mirror and passed to the photo transistor to increase the photo current in the photo transistor,
detecting "original absent." When, on the other hand, there is an original between the LED and the mirror, there is no reflection light from the mirror,
no increase in the photo transistor photo current, detecting "original present." This circuit is provided with the automatic adjustment feature. The LED
anode is connected to R133 to keep the current flowing through the LED constant.
On the other hand, the photo current of the photo transistor is converted into a voltage value by the load resistor R76 and R78, passed through the
noise filter composed of R39 and C48 to IC2 10 pin and the CPU 58 pin. R108, R112, and IC2 form the voltage comparator, which compares the
input voltage from the sensor and the threshold voltage (about 2V) generated by dividing +5V with R107 and R111. When the sensor input voltage
exceeds the threshold voltage, IC2 13 pin output is driven to LOW and passed to the CPU 17 pin as the "original present" signal. The CPU 58 pin is
an A-D input pin, which converts an analog voltage into a digital value in the CPU.
Since there are some variations in the sensor sensitivities, the voltage of "original absent" is used as the reference voltage for automatic adjustment
of the sensor sensitivity. That is, the sensor voltage of "original absent" is A-D inputted and the D-A output voltage is changed to change the PWM
outputted from G/A. Then the CPU controls the sensor voltage to the constant level, and the voltage is outputted from G/A. The PWM output value is
unique to each element, and its value is stored in the EEPROM (IC10).
[d] Original end sensor 2 (DED2)
Original end sensor 2
SLR-935A
A
DED2
K
The original end sensor 2 is the reflection sensor, and is integrated with the LED and the photo transistor.
Infrared light emitted from the LED is reflected by the mirror and passed to the photo transistor to increase the photo current in the photo transistor,
detecting "original absent." When, on the other hand, there is an original between the LED and the mirror, there is no reflection light from the mirror,
no increase in the photo transistor photo current, detecting "original present." This circuit is provided with the automatic adjustment feature. The LED
cathode is connected to R144 to keep the current flowing through the LED constant.
On the other hand, the photo current of the photo transistor is converted into a voltage value by the load resistor R25 and R41, passed through the
noise filter composed of R40 and C2 to IC5 6 pin and the CPU 62 pin. R44, R77, and IC5 form the voltage comparator, which compares the input
voltage from the sensor and the threshold voltage (about 2V) generated by dividing +5V with R44 and R77. When the sensor input voltage exceeds
the threshold voltage, IC5 7 pin output is driven to LOW and passed to the CPU 43 pin as the "original present" signal. The CPU 62 pin is an A-D
input pin, which converts an analog voltage into a digital value in the CPU.
Since there are some variations in the sensor sensitivities, the voltage of "original absent" is used as the reference voltage for automatic adjustment
of the sensor sensitivity. That is, the sensor voltage of "original absent" is A-D inputted and the PWM from G/A is changed to change the photo
transistor light quantity. Then the CPU controls the sensor voltage to the constant level, and the voltage is outputted from G/A. The PWM output
value is unique to each element, and its value is stored in the EEPROM (IC10).
10
LE D
CN1 2-1
CN1 -10
DTDLED
11
CN1 2-2
CN1 -11
DTD
12
CN1 2-3
CN1 -12
SGND
Reverse timing sensor input circuit
B4B-PH-K-S
C
4
PH110M
+5V
CN25-4
3
VOUT
CN25-3
E
2
LE D
CN25-2
1
N.C.
CN25-1
Orignal end sensor 2 input circuit
+5V
C
R75
B
DA 3
Q1
E
C40
+5V
R133
R76
28
CN1-28
+5V
27
CN1-27
DED2
R144
26
CN1-26
DEDLED
R4 1
R2 5
E
R43
B
Q1
C
C3 9
– 24 –
+5 V
+5V
+5V
R116
R112
R7 8
11
+
12
R3 9
10
-
C4 8
R108
+5V
+5V
R143
R7 7
D1 1
IC5-2
5
R2 0
+
7
R4 0
6
-
DA 4
DEDAD
C2
R4 4
TP70
R9 4
17
P62/INT3
TP10
58
P47/AN7
TP72
DED2
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