Sharp AR-651 (serv.man23) Service Manual ▷ View online
AR-651/810 PAPER FEEDING SECTION 9 - 3
(10) Tray-up sensor
This sensor detects the tray position when the paper lift plate of the cassette and tandem LCF is in the
up position.
(11) Bottom sensor
This sensor detects when the paper lift plate is at the lower unit position for the cassette and tandem
LCF.
AR-651/810 PAPER FEEDING SECTION 9 - 4
9. 3. Operation
9. 3. 1. Operation of bypass pickup roller
When the bypass pickup solenoid is turned ON, the plunger is pulled and the lever is rotated and lowered.
The pickup arm, which is linked with the lever, is also lowered with the lever by its own weight. When the
bypass pickup solenoid is turned OFF, the pickup arm is brought up by the spring force.
The driving force transmitted through the bypass feed clutch is also transmitted to the bypass feed roller
through the shaft and then to the bypass pickup roller through the timing belt. The roller is rotated by this
driving force.
9. 3. 2. Operation of cassette pickup roller
When the cassette is inserted, the protrusion at the rear side of the cassette pushes the lever (a) in the A
direction. Then, the pickup roller and roller holder are lowered by the spring force of (B).
Bypass pickup roller
Spring
Bypass feed roller
a
A
B
Bypass pickup solenoid
Lever
Pickup arm
Shaft
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.
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