Sharp FO-4450 Service Manual page 52

FO-4450U/FO-CS1
5. PAPER PATH
Paper can be fed into the printer from the Multi Purpose Tray (250 sheets)
or from the Manual Feed Port (1 sheet).
Installing the 2nd Paper Cassette Unit (FO-CS1) (500sheets) adds an-
other feeding method.
The paper fed by the Paper Take-Up Roller is transported to the Image
Transfer Roller, Fusing Roller and then Paper Exit Roller. After this, the
paper is fed out onto the Print Tray.
6. PAPER TAKE-UP SECTION
6-1. Multi-Purpose Tray
When the Paper Take-Up Solenoid (SL1) is energized, the drive of the
Main Motor (M1) is transmitted to the Paper Take-Up Roller via the Pa-
per Take-Up Gear (one-way clutch) to turn the Paper Take-Up Roller
one revolution. At the same time, the Depressing Cam turns and lifts the
Paper Lifting Plate, and the first (top) sheet of paper on the tray is fed to
the printer. The Fixed Separating Pad is used for the paper separation
system. It prevents the second and subsequent sheets of paper from
being fed together with the top sheet. The actual length of the paper is
detected using the period of time through which the Paper Take-up Sen-
sor (PS1) remains energized (or through which the paper moves past
the sensor) and it is determined whether the actual length matches the
paper length specified by the controller.
Paper Take-up
Sensor (PS1)
Paper Take-up
Gear
Paper Take-up Solenoid (SL1)
Print Exit
Paper Take-up Roller
Depressing Cam
Paper Empty
Sensor (PE1)
Paper Tray
Fig. 5
Exposure
Drum
Print Head
Cartridge
Unit
Development
Toner Cartridge
2nd Option Cassette Unit
Fig. 4
7. DRUM CHARGE
The PC Drum is charged with static electricity before laser exposure.
The Drum Charge Brush and the Pre-charge Film are used for the charg-
ing method.
The Drum Charge Brush and Pre-charge Film charging generate little
ozone in the printer. Because the charge is directly applied to the PC
Drum, the PC Drum can be charged by low voltage. In addition, the
charge applied to the PC Drum is stable and even.
The Pre-charge Film supplies the charge to the PC Drum before being
charged by the Drum Charge Brush to improve the charging efficiency.
The Drum Charge Brush is turned by the drive of the Main Motor (M1)
via a gear.
The electric potential on the surface of the charged PC Drum is approxi-
mately-800 V.
Laser Exposure
Development
Sleeve Roller
Drum Cover
1
3 – 4
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Fusing
PC Drum
Image
Transfer
Drum Cartridge
Rotating Charge Brush
Paper Dust Remover
Pre-charge Film
Image Transfer Roller
PC Drum
charged surface:
approx. -800V
1. Drum Charge Brush
2. PC Drum
3. Earth
4. Drum Charge Brush
4
2
Voltage
3
Fig. 6