Sharp FO 4400 Service Manual - Page 56

FO-4400U 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 another 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. Print Exit Exposure Print Head Unit Drum Cartridge Development Toner Cartridge Fusing PC Drum Image Transfer 2nd Option Cassette Unit Fig. 4 6. PAPER TAKE-UP SECTION 7. DRUM CHARGE 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 Paper 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 Sensor (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. 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 charg 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. Drum Cartridge Paper Take-up Roller Depressing Cam Paper Take-up Sensor (PS1) Paper Empty Sensor (PE1) Laser Exposure Rotating Charge Brush Paper Dust Remover Paper Take-up Gear Paper Take-up Solenoid (SL1) Fig. 5 Paper Tray 3 - 4 Development Sleeve Roller Drum Cover 1 2 Pre-charge Film Image Transfer Roller PC Drum charged surface: approx. -800V 1. Drum Charge Brush 2. PC Drum 3. Earth 4 4. Drum Charge Brush Voltage 3 Fig. 6