Sharp AR-810 (serv.man13) Service Manual ▷ View online
AR-651/810 PAPER FEEDING SECTION 9 - 5
9. 3. 3. Paper separation
This model is equipped with a separation roller which
works to prevent multiple paper feeding. The sepa-
ration roller unit consists of the feed roller, separa-
tion roller, torque limitter, etc., as shown at the right.
The feed roller is rotated by the feed clutch in the
direction of the arrow (
) at the same timing as
the pick up roller rotation.
The figure at lower right shows how duplicate feed-
ing is prevented: Since the friction between two
sheets is small, the lower sheet is not transported
any further while the upper sheet is transported by
the feed roller in the direction of the arrow (
).
[Example]
• When only one sheet enters between the rollers:
Since the transporting force of the feed roller is
greater than the braking force of the separation
roller, the separation roller follows the feed roller,
making the sheet go forward to the registration
roller.
• When two sheets enter between the rollers at the
same time:
Since the transporting force of the feed roller and
the breaking force of the separation roller are
greater than the frictional force between two
sheets, the paper A is transported to the direction
of the arrow (
) and the paper B is braked by
the separation roller and is not transported any
further.
Feed roller
Separation roller
Torque limitter
Feed roller
Separation roller
A
B
AR-651/810 PAPER FEEDING SECTION 9 - 6
9. 3. 4. General operation
[A] From power ON to standby status
(1) When the copier is turned ON, the tray-up motor is activated and the 1st cassette tray starts to rise.
When the tray-up sensor is turned ON (H
촞
L), the tray-up motor is turned OFF and the tray is stopped.
At this time, if the empty sensor is OFF (L), it is judged that there is no paper in the cassette. With the
empty sensor being ON (H), there is paper in the cassette. The tray stops at the raised position
regardless of availabilty of paper.
Then the tray-up motor starts to rotate in the reverse direction and 2nd cassette starts to be lifted. The
2nd cassette tray is stopped in the same manner as the 1st cassette tray and the empty sensor
detects if there is paper in the cassette.
(2) If the cassette is not completely inserted when the copier is turned ON, the tray for that cassette is not
raised. When the cassette is inserted completely, the tray is raised and checked for the availability of
paper.
(3) If either of the sensors at the transport path are ON (meaning there is paper on the transport path) when
the copier is turned ON, it is determined that a paper jam has occurred and paper lift operation is
disabled until after the jamed paper is removed.
[B] Standby status
(1) After the tray is moved up and availability of paper is checked as described above, the copier enters
the standby state. In the standby mode, the tray remains at the raised position.
(2) When a cassette is inserted or removed in the standby state, the tray is raised again to check the
availability of paper.
[C] Bypass feeding
•
The bypass sensor detects the availability of paper.
•
The bypass feed clutch is turned ON and the bypass pickup roller and bypass feed roller rotate.
•
The bypass pickup solenoid is turned ON and the bypass pickup roller is lowered to start feeding.
•
The leading edge of the paper turns ON the registration sensor and the paper is aligned with the
registration roller.
•
The bypass feed clutch is turned OFF and the bypass pickup roller and the bypass feed roller are
stopped, and then the bypass pickup roller is raised.
•
The registration motor is turned ON and paper is transported to the transfer unit.
[D] Cassette feeding
•
The feed clutch is turned ON and the pickup roller and feed roller rotate to start feeding.
•
The leading edge of paper turns ON the transport sensor, then the feed clutch is turned OFF and
the transport clutch is turned ON.
•
The leading edge of paper turns ON the registration sensor and paper is aligned with the registration
roller.
•
The transport clutch is turned OFF and the transport roller is stopped.
•
The registration motor and transport clutch are turned ON and paper is transported to the transfer unit.
AR-651/810 PAPER FEEDING SECTION 9 - 7
[E] Tandem LCF
(E-1) From power ON to standby status
(1) When the copier is turned ON, the power is supplied to start the pre-running operation. The tandem LCF
tray-up motor starts to rotate forward and raises the tray. The tandem LCF tray-up motor is turned OFF
when the tray turns ON the tandem LCF tray-up sensor, and the tray is then stopped. At this time, it is
judged whether there is paper on the feed side tray when the tandem LCF empty sensor is ON. On the
other hand, the absence of paper on the feed side tray is assumed when the sensor is OFF, and the
tandem LCF standby side empty sensor is subsequently checked. When the tandem LCF standby side
empty sensor is OFF, paper is absent on the standby side tray and it is therefore assumed that there
is no paper in the tandem LCF. When the tandem LCF standby side empty sensor is ON, paper on the
standby side tray is moved onto the feed side tray. The tandem LCF tray-up motor is rotated in reverse
and lowers the feed side tray. The lowered tray turns ON the tandem LCF tray bottom sensor, and the
tandem LCF tray-up motor is turned OFF to stop the tray. The end fence solenoid and pickup solenoid
are then turned ON. The end fence motor rotates forward and the paper on the standby side tray is
moved onto the feed side tray. The end fence motor is stopped for a second when the end fence stop
position sensor is turned ON, and the motor immediately starts to rotate in reverse to return the end
fence to the position where the end fence home position sensor is turned ON. When the returning
operation is started, the end fence solenoid and pickup solenoid are turned OFF, and the tandem LCF
tray-up motor is rotated forward to raise the tray. The tandem LCF tray-up motor is turned OFF when the
tray being raised turns ON the tandem LCF tray-up sensor and stops the tray. At this time, the pres-
ence of paper is judged when the tandem LCF empty sensor is ON.
(2) Whe the power is turned ON after the tray unit is removed, the tandem LCF tray-up motor is turned ON.
The tray is raised as soon as the tray unit detects that the tray is fully inserted.
(3) If either of the tandem LCF feed sensors is ON (there is paper at the transportation path) when turning
ON the power, a paper jam is judged and the operation is disabled until the paper is removed.
AR-651/810 PAPER FEEDING SECTION 9 - 8
(E-2) Standby status
(1) Trays detect the paper as described above, and the copier goes into the standby status.
(2) The tray goes down automatically when the tray unit is removed and is raised as soon as the tray unit
is reinstalled it then checks if there is paper in the tray.
(E-3) From the start to the end of copying
(1) The drum motor of the copier is turned ON when the [START] key is pressed. The transport motor is
also turned ON to drive the transfer belt unit.
(2) When the copier judges that the tandem LCF is ready for feeding paper, it turns ON the tandem LCF
feed clutch on the selected tray. This clutch drives the pickup roller and feed roller to feed paper from
the tray.
(3) In a specified time after the feeding has started, the appropriate transport clutch is turned ON to drive
the transport roller.
(4) The leading edge of the paper turns the feed sensor ON. These are located right next to the exit side of
the selected tray. The feed clutch is then turned OFF and feeding from the tray is complete.
(5) The paper is then transported to the copier by the transport rollers. If the trailing edge of the previous
sheet still remains at the transport sensor when the leading edge of the paper reaches the feed sensor,
the transport clutch is turned OFF to stop the transport of the paper at that time.
(6) The trailing edge of the paper turns the feed sensor OFF. These are located right next to the exit side of
the selected tray. The selected tray then becomes ready for feeding the next sheet of paper, and the
procedures (2) to (5) are repeated.
(7) When the copying operation is completed, the drum motor, the tandem LCF transport motor and transport
clutch are turned OFF and the transport roller is stopped.
(E-4) Error detection
a) Jam detection
(1) A paper jam occurs in the following cases.
a. Feed sensor is not turned ON within a specified time after the feeding has started.
b. The leading edge of the paper does not pass the feed sensor in the transport path within a fixed
time.
(2) Open the feed side lower cover and remove all the paper remaining on the transport path and close the
cover to clear the jammed paper. If either of the feed sensors is still ON when the cover is closed, it is
determined that there is still paper on the transport path and the paper jam status is not canceled.
(3) When a paper jam occurs in the paper feeder during multiple copying, the sheet that was fed before the
jam is copied normally.
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