Sharp FACSIMILE FO-4500 Service Manual page 63

6. PRINT PROCESSING
Fusing
Drum Cartridge
Drum
Charging
Image
Transfer
2nd Transport
Unit
CASSETTE 1
7. PAPER TAKE-UP SECTION
Paper can be fed into the printer from the Multi Purpose Tray or from
the Manual Feed Port (1 sheet).
Installing the Second Tray adds another feeding method.
The paper fed by the Paper Take-Up Roller is transported to the
Transport Roller, Fusing Roller and then Paper Exit Roller. After this,
the paper is fed out onto the Print Tray.
The starting position of an image is decided by the Paper Take-Up
Sensor (PC1).
7-1. Multi-Purpose Tray
When the Paper Take-Up Solenoid is energized, the drive of the Main
Motor (M1) is transmitted to the Paper Take-Up Roller via the Paper
Take-Up Clutch (one-way clutch) to rotate the Paper Take-Up Roller
one revolution. At the same time, the Depressing Cam rotates and
releases the Paper Lift-Up Plate to feed the top (first) sheet of paper.
The Fixed Separating Pad is used for the paper separation system. It
prevents the second or later sheets of paper from being fed together
with the top paper.
A Paper Empty Sensor in the Multipurpose Tray senses when the
paper tray is empty. Additionally, a sensor informs the Printer Control
PWB if the paper guide is adjusted to Legal and that legal sized paper
is installed.
Upper Fusing Roller
Lower
Fusing
Roller
PC Drum
Image
Transfer Roller
Paper Lift-Up Plate
Fixed Separating Pad
Transport Roller
Paper Take-Up
Sensor (PC1)
Paper Take-Up
Clutch
Print Head Unit
Print Exit
Exposure
Toner
Hopper
Development
Toner Cartridge
Fig. 7
Paper Exit Roller
Paper Exit Sensor
(PC3)
When SL1 is de-energized
Paper Take-Up
Roller
Depressing
Cam
Paper
When SL1 is energized
Paper Take-Up
Solenoid (SL1)
Paper Lift-Up Plate
Fig. 8
8. DRUM CHARGE
The PC Drum is charged with static electricity before laser exposure.
The Rotating Charge Brush and the Precharge-film are used for the
charging method.
The rotating brush charging and the Precharge-film charging generate
little ozone in the printer. Because the charge is directly given to the
PC Drum, the PC Drum can be charged by low voltage. At the same
time, PC Drum can be charged stably and evenly.
The Precharge-film charging supplies the charge to the Rotating
Charge Brush to improve the charging efficiency.
The Rotating Charge Brush is turned by the drive of the Main Motor
(M1) via a gear.
Drum Cartridge
Rotating Charge
Brush
A
A: Drum
Charging
Bias
B: Drum
Ground
B
9. LASER EXPOSURE
An invisible static image is made by the laser beam emitted from the
Print Head Unit.
In the sub-scanning direction (vertical direction)
When the printer receives the PRINT signal, the Polygon Motor and
the Main Motor rotate and the paper is fed into the printer.
The printing in the sub-scanning direction is started when the PWB-P
sends the VIDEO signal to the Print Head a certain time after the
leading edge of the paper activates the Paper Sensor (TOD signal).
The print starting position of the 2nd line is decided by delaying the
VIDEO signal sending timing.
In the scanning direction (horizontal direction)
The SOS Sensor is installed on the Laser Diode Control Board (PWB-
D) to unify the laser emission timing for each scan line.
Charged Surface
Laser exposed surface:
approx. -50V
PWB-D
SOS Sensor
Laser Diode
3 – 6
Drum Charging &
Precharge-film Bias
PWB-F
CN4
8
PC Drum
Protecting Shutter
1
CN1
Charged Surface:
approx. -800V
Rotating Charge
PC Drum
Brush
Cleaner
Precharge-
film
Precharge-
film
Fig. 9
Reflector Mirror CN10
CN5
M2
Fig. 10
FO-4500H
PWB-A
1
8
PWB-A
1
4
1
7