Sharp AL-840, Digital Copier Photoconductor drum unit, Developing unit, Transfer charger roller

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b. Major parts functions and operations

 

 

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3)

 

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10)

 

 

 

2)

 

 

 

 

 

 

 

 

 

 

4)

 

9)

 

 

 

 

 

 

 

 

 

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5)

 

 

8)

 

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6)

 

1

Developing

5

Toner seal

9

Discharge

 

roller

 

 

 

brush

2

Doctor

6

Transfer

10

Main charger

 

 

 

charger roller

 

brush

3

Toner stirring

7

Separation

11

Toner seal

 

plate

 

electrode

 

 

4

Toner supply

8

Phot conductor

12

Discharge

 

roller

 

drum

 

(Earth) sheet

<1> Photoconductor drum unit

The photoconductor surface is charged and latent electrostatic im- ages are formed, then visible images are formed with toner.

1) Photoconductor drum

Latent electrostatic images are formed and visible images are formed with toner.

An OPC (Organic Photo Conductor) drum is used. The OPC drum surface is negatively charged by the main charger brush.

When laser beams are radiated on the OPC drum, the electric resis- tance at the radiated area is reduced to generate an electric charge inside the OPC drum. As a result, the charges on the OPC drum are removed. This process is used to form latent electrostatic images.

CTL

(Charge Transfer Layer)

OPC layer

CGL

(Charge Generation Layer)

Aluminum layer

2) Main charger brush

The main charger brush charges the OPC drum surface. It is com- posed of brush textures and of a roller shape.

A high voltage of AC 600V (P-P) is applied to DC-850V to charge the brush.

The main charger brush is in contact with the OPC drum. By supply- ing electric charges to the OPC drum, the OPC drum is charged to about –850V.

3) Toner seal

The OPC drum has two toner seals. The toner seals are used to prevent residual toner on the OPC drum from leaking outside.

<2> Developing unit

Visible images are formed with toner over the latent electrostatic images formed on the OPC drum surface. Toner is filled in the developing unit.

1) Developing roller

The developing roller is made of urethane and it has considerably high electrical resistance. It is flexible and pressed onto the OPC drum. Toner is attached to the latent electrostatic images on the OPC drum to make visible images. A voltage of DC-310V/+200V is applied to the developing roller. A voltage of –310V is applied when develop- ing. A voltage of +220V is applied when cleaning.

2) Doctor

The doctor is pressed onto the developing roller. It adjust the toner quantity on the developing roller surface.

The doctor is made of a conductive material.

3) Toner supply roller

The toner supply roller transports toner to the developing roller.

4) Toner stirring plate

The toner stirring plate stirs toner in the developing unit to transport toner to the developing roller smoothly.

5) Toner seal

The toner seal prevents toner from leaking outside the developing unit.

6) Discharge (Earth) sheet

The discharge sheet maintains the developing roller surface potential at a constant level.

<3> Transfer charger roller

The transfer charger roller is made of urethane and its electrical resistance is considerably high. It is flexible and pressed onto the OPC drum.

A high voltage of AC600V (P-P) is applied to DC +3500V.

Paper transported from the paper feed section is charged positively and negatively charged toner on the OPC drum are transferred onto the paper.

During cleaning, a voltage of –850V is applied.

<4> Separation electrode

The separation electrode is connected to the drum earth. This dis- charges paper charged positively in the transfer section to reduce potential difference with the OPC drum, reducing electrostatic attrac- tion power between paper and the OPC drum, facilitating paper separation.

<5> High voltage unit

The high voltage is made by the invertor system, and is supplied to the main charger unit, the transfer unit, and the developing roller.

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Contents Model AL-800/840 Operating Principle High voltage power PWB Fusing/paper exit sectionPower PWB Scanner read sectionCopy mode Paper path and imagingImage process and data flow Printer mode Data Flow DiagramOutline Paper feed, paper transport sectionMajor parts PUSPUS PE Sensor PempPIN Sensor Paper SizeOperation Paper release operation Scanner reading section CCD CCD OUT MhpsCCD SensorAsic IC8 Mcupcu PWB Wiring diagramScanner writing section Block diagramSync Mcupcu PWB LSU PWBICU PWB Image process section Image forming process diagram OPC Photoconductor sectionDevelopment section Transfer/separation section CPU IC5 System diagramDeveloping unit Photoconductor drum unitTransfer charger roller Separation electrodeActual image forming process Paper Transfer roller Residual toner OPC drum OPC drum surface potential OPC drum surface potential and developing biasFusing/paper exit section ModelRTH Hlon HLL AC PowerComp AMP CN2Drive section Wiring diagramAsic CPU IC5 MEN MMT0 MMT1Major sections operations and functions Electrical sectionHigh voltage power PWB Power PWBCopy lamp control PWB Operation PWB Copyright 1998 by Sharp Corporation
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