Sharp AR-651 (serv.man19) Service Manual ▷ View online
AR-651/810 RADF (DOCUMENT FEEDER) 16 - 61
(d) Two sheets of A4 two-sided original
0
1000
2000
3000
4000
5000
6000
7000
(ms)
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
Upw
ord
Stop
Do
wnw
ord
Stop
Stop
CW
CCW H
CCW L
CCW H
CCW L
CCW H
CCW L
CW L
CW H
Stop
CW L
CW H
Stop
CW L
CW H
Upper limit sensor
Lo
w
er limit sensor
T
ra
y
lift motor
Empty sensor
F
eed motor
Or
iginal length sensor
Registr
ation sensor
Read sensor
Read motor
Reading star
t signal(SCN-STR)
Large or
iginal e
xit motor
Large or
iginal e
xit solenoid
Disengagement solenoid
Large or
iginal e
xit sensor
Inter
mediate tr
anspor
t sensor
Small or
iginal e
xit motor
Small or
iginal re
v
erse sensor
Small or
iginal e
xit sensor
Small or
iginal e
xit solenoid
313
322
348
671
1129
1452
741
562
631
1412
1239
1003
811
761
1035
1129
1233
1365
1858
2009
2561
3209
3498
3592
3983
4003
4576
5682
6348
5024
4618
4886
5094
5303
4967
5020
5221
4321
3732
4472
6097
6124
6323
4596
4897
5105
5316
4917
2013
2122
2424
2444
2841
2632
2726
3231
3487
3614
4025
4565
3759
3958
4348
4458
2092
2145
2494
2547
2748
2143
2621
2826
1885
1995
1385
1233
1580
2164
4043
4637
2076
2895
3359
3209
4187
5662
6542
4647
4257
4630
6612
6985
4807
7162
7002
7200
4090
4207
4815
4176
3259
3189
6150
3785
4150
4340
6695
4717
7072
7220
4554
6515
6909
4076
5732
6441
6455
6562
6531
5832
3938
6303
4539
5368
3696
2123
2726
3806
5199
3455
4321
5928
4596
2826
3696
5303
1858
3455
4321
5928
2097
2444
2632
2726
3498
3592
4560
4917
5105
5199
6108
964
1151
1858
2009
2561
4321
4472
5034
950
1885
1995
2494
2547
4348
4458
4967
5020
1024
2086
2621
2748
3487
3614
4549
5094
5221
6097
2600
3466
5073
1735
3332
4194
5805
3702
1343
974
3437
950
3098
3200
3214
974
3447
423
652
1204
1433
3048
3458
691
984
3447
3527
572
1433
3532
1064
652
1353
3855
1054
3517
585
1435
3537
3845
5199
5704
AR-651/810 RADF (DOCUMENT FEEDER) 16 - 62
16. 11. Circuits
(1) Input circuits for read sensor, large original exit sensor, small original reverse sensor and original
length sensor
Since the read sensor, large original exit sensor, small original reverse sensor and original length sensor
have almost the same circuitry, only the input circuit for the read sensor is described as followed.
This circuit consists of the voltage-current conversion circuit, which adjusts the amount of light of the
infrared LED, and the voltage comparison circuit, which compares the voltage output from a
phototransistor (PTr) with a reference voltage and converts the output voltage into digital signals.
The read sensor is a mirror reflection sensor, and consists of a pair of emission elements (infrared
LEDs) and a light receiving element (PTr). Both elements have a light axis running in the same direction.
There is a mirror on the extended light axis of these elements. When there is no original between the
elements and the mirror, infrared light emitted from LED is reflected by PTr in high reflectance. If there is
an original, light emission to the mirror and reflected light from the mirror are blocked by the original, and
the reflected light entering PTr becomes extremely small.
When a large amount of light is entering PTr (this means there is no original) the optical current flowing
in the PTr is increased, and the voltage of IC6-8pin becomes higher due to a drop in voltage caused by
R109. IC6 is a comparator which compares the reference voltage input to 9pin (non-reverse input
terminal) with the signal voltage of 8pin (reverse input terminal). If the voltage of 8pin is higher, the
output level (IC6-14pin) is "L". On the contrary, when the amount of the incoming light is small (this
means there is an original), the voltage of 14pin is low and the voltage of IC6-14pin becomes "H". R56,
C56 and C57 are noise filters. This circuit has an automatic sensitivity adjustment function to control the
unevenness of the sensor sensitivity. Uneven sensor sensitivity is corrected by controlling the machine
to have a constant PTr voltage when there is no original. The intensity of the infrared light emitted from
the LEDs is changed to adjust the PTr voltage.
When the sensor sensitivity adjustment mode is selected, the PTr output voltage (analog value) is
measured by the A-D input terminals of CPU. The output voltage of the D-A converter is changed to
keep the PTr output voltage to a certain level, and the LED current is adjusted by a voltage-current
conversion circuit consisting of IC11, R65, Q6, etc. Each machine; has a different D-A output voltage
value, which is stored in the volatile memory.
AR-651/810 RADF (DOCUMENT FEEDER) 16 - 63
(2) Irruptive current control circuit
This circuit controls the irruptive current flowing into the current regeneration condensers mounted on
the drive circuits for the motors to a certain value. The circuit consists of a posister (PTH1) which
controls the current and FET (Q12) which supplies the current in normal conditions.
Base current is not supplied to Q2 and it becomes OFF after the RADF open/close switch and cover
open/close switch are turned OFF till the cathode voltage of ZD3 reaches the zener voltage. At this
time, both voltages are set by R36 and C107. Q12 is turned OFF correspondingly to supply the current
to PTH1, and the current regeneration condensers are charged.
After the current regeneration condensers are fully charged and when the cathode voltage of ZD3
exceeds the zener voltage after the time allowance given by C107 and R36, a base current is supplied
to Q2 to turn it ON and Q12 comes ON correspondingly. The current limitation is canceled and the
current flowing in the PTH1 starts to be supplied to Q12.
R66, R67, R68 and R69 are discharge resistors to capture charge stored in the current regeneration
condensers right after either of the RADF open/close switch or cover open/close switch is opened. The
circuit consisted of PTH2 and D1 captures the charge stored in C107 right after either the RADF open/
close switch or the cover open/close switch is opened, and also controls incoming current for
instantaneous opening/closing of the cover.
AR-651/810 RADF (DOCUMENT FEEDER) 16 - 64
(3) Drive circuit for read motor
This circuit controls the rotation/stoppage and the direction of rotation, excitation mode and motor
current of the read motor.
A drive clock signal (RMOT_CLK) and rotation direction signal (CWB) are input to control the speed and
direction of the motor rotation. M1 and M2 are the exciting mode setting signals.
The PWM signal of RMOT_CU is separated and smoothed at R80, R76 and C91, and it is input into
IC10-7pin(Vref) to set the motor current value. The motor current value can be changed by altering
duties of the PWM signal.
(4) Drive circuit for feed motor
This circuit controls the rotation/stoppage, the direction of the rotation of the feed motor and the motor
current. The drive pattern signal is input into IC15-6, 7, 8, 9 to control the speed and direction of the
motor rotation.
The PWM signal is input into FMOT_CU and separated and smoothed at R89, R87 and C87, and it is
input into IC15-12pin (Vref) to set the motor current value. The motor current value can be changed by
altering duties of the PWM signal.
Click on the first or last page to see other AR-651 (serv.man19) service manuals if exist.