Sharp AL-840, AL-800 User Manual 2

SERVICE MANUAL

CODE: 00ZAL840//B1E

BASIC MANUAL DIGITAL COPIER

MODEL AL-800/840

CONTENTS

[ 1 ] OPERATING PRINCIPLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1

1. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1

2. Outline of operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3

A. Paper path and imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3

B. Image process and data flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3

3. Operations of each section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5

A. Paper feed, paper transport section . . . . . . . . . . . . . . . . . . . . . . . . . .1-5

B. Scanner (reading) section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

C. Scanner (writing) section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-12

D. Image process section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-14

E. Fusing/paper exit section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-25

F. Drive section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-27

G. Electrical section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-28

Parts marked with "!" is important for maintaining the safety of the set. Be sure to replace these parts with specified ones for maintaining the safety and performance of the set.

This document has been published to be used

SHARP CORPORATION

for after sales service only. The contents are subject to change without notice.

1. Block diagram

Control signal, detection signal, drive signal, control data line

Image data signal line

Image (light)

Power line

Paper path line

SCANNER HOME

POSITION

SENSOR

COPY LAMP

LIGHT QUANTITY

SENSOR

MIRROR

DOCUMENT

LENS

SCANNER (READING) SECTION

CCD

SCANNER

MOTOR

[1] OPERATING PRINCIPLE

1 – 1

PRINT PWB

OPERATION PWB

LAMP (LED)

KEY

MAIN MOTOR

COPY LAMP

CONTROL PWB

FAN MOTOR

MOTOR DRIVER

HIGH VOLTAGE POWER PWB

FUSING/PAPER EXIT SECTION

PAPER

EXIT

PAPER

EXIT

ROLLER

HEATER LAMP

PRESSURE

ROLLER

HEAT

ROLLER

TEMPERATURE

FUSE

TEMPERATURE

SENSOR

ROLLER

PAPER EXIT

DETECTOR

A/D

ONVERTOR

MEMORY

CPU

ASIC

MCU (PCU) PWB

IMAGE PROCESS SECTION

MAIN

CHARGER

PHOTOCONDUCTOR

SEPARATION ELECTRODE

TRANSFER

ROLLER

DEVELOPING

ROLLER

LASER DIODO

LENS

MIRROR

MEMORY

ASIC

ICU PWB

SCANNER (WRITE) SECTION

LASER BEAM

SENSER

POLYGON

MIRROR

PAPER FEED SECTION

PAPER FEED

ROLLER CLUTCH

PAPER WIDTH

DETECTOR

PAPER EMPTY

DETECTOR

PAPER ENTRY

DETECTOR

SCANNER

MOTOR

PAPER

FEED

ROLLER

I/F

PARALLEL

PAPER

TRAY

HOST(PC)

PAPER

POWER PWB

AC POWER

Scanner (reading) section

Fusing/paper exit section

Scanner (writing) section

Image process section

Scanner (read) section

In this section, the copy lamp (cathode ray tube, Xenon lamp) radiates light onto a document, and the reflected light is detected by the image sensor (CCD element) to convert into electrical signals (analog signals), which are sent to the MCU PWB.

MCU (ICU) PWB

The image data from the scanner (reading) section are converted into digital signals and subject to image process (correction, etc.), and converted into dot image data and outputted to the scanner (writing) section.

During printing, the dot image data from the ICU PWB are outputted to the scanner (writing) section directly. The engine status data are outputted to the ICU PWB.

The loads (motor, solenoid, etc.) are controlled according to the sensor/detector signal.

The above operation is performed by the CPU, ASIC, and memory.

ICU PWB

Print data (compressed data) sent from the host are developed and converted into dot image data and outputted to the scanner (writing) section. The engine status data sent from the MCU (PCU) PWB are outputted to the host (PC).

Scanner (writing) section

In this section, the dot image data sent from the MCU PWB are converted into laser beams (ON/OFF), which is scanned to form latent electrostatic images on the OPC drum.

Paper feed section

The paper feed roller feeds paper to the transfer section. The paper feed operation is controlled by the paper fed roller clutch

and the paper feed roller clutch solenoid.

Image process

This section is composed of the photoconductor section, the developing section, and the transfer/separation section. The images formed by laser beams in the scanner (writing) section are formed into latent electrostatic images on the photoconductor and converted into visible images by toner development.

Paper feed section

The operations of this section are composed of five processes; exposure, development, transfer, separation, and discharge.

The OPC drum is used as the photoconductor drum, and one-component toner is employed.

For charging, the rotation brush is employed. For transfer, the roller is employed to eliminate ozone generation. In addition, t is compact.

The high voltage required in this section is supplied by the high voltage PWB.

Fusing/paper exit section

Toner is fused to the paper in the fusing/paper exit section using heat and pressure.

The heat roller surface temperature is detected by the fusing temperature sensor to maintain the constant fusing temperature (155 ˚C).

The heater lamp is driven by the power PWB unit.

Operation PWB

The operation PWB displays various information and supplied the key operation signals to the MCU (PCU) PWB.

High voltage power PWB

The high voltage power PWB outputs the high voltage for the main charger, the developing bias, and the transfer charger. In addition, the main motor drive circuit is built into the PWB.

Main motor.

The main motor drives the paper feed section, the transport section, the image process section, and the fusing section.

The main motor drive circuit is built into the high voltage power PWB.

Copy lamp control PWB

The copy lamp light quantity is controlled to provide necessary light quantity even though the conditions of the scanner (reading) section are changed.

The copy lamp drive voltage is controlled by the output level of the light quantity sensor in the scanner (reading) section.

Power PWB

The power PWB outputs the DC power voltages (+24V, +5V, +3.3V, +12V), and drives the heater lamp.

1 – 2

2. Outline of operations

A. Paper path and imaging

Paper is fed, transported, and discharged through the path indicated with the arrow in the figure below.

1) Paper feed (Paper on the paper tray is fed to the transfer section by the paper feed roller.)

2) Image transfer (The toner image on the photoconductor is transferred onto the paper by the transfer roller.)

3) Fusing (The toner image on the paper is fused by the heat roller and the pressure roller.)

4) Paper exit (The paper is discharged to the paper exit tray by the paper exit roller.)

B. Image process and data flow

(1) Copy mode

C1) Images scanned by the image sensor (CCD element) is con-

verted into electrical signals (analog signals) and outputted to the MCU PWB. (CCD unit)

C2) Image data outputted from the scanner (reading) section are

converted into digital signals. (CCDD0-7)

C3) Image process (area separation, filter process, gamma correc-

tion, resolution conversion, zooming) is performed by the ASIC and the line memory (SRAM). The dot image data, the resolution of which is converted from 400dpi to 600dpi, are sent to the data select section. (Image data (LD))

C4) The data are passed through the data select section to the

scanner (writing) section. (Image data (V DATA)) In the multi copy mode, image data of one sheet are stored in

the DRAM. (Sharp version only)

1 – 3

(2) Printer mode

P1) Print data (compressed data) are sent from the host. (Image

data (Data 1 – 8)

P2) Print data are developed by the ASIC and the line memory and

converted into the full dot image data and sent to the data select section. (Image data)(VIDEO)

P3) The data are sent through the data select section to the scan-

ner (writing) section. (image data) (V DATA)

DATA FLOW DIAGRAM

CCD PWB

CCD

Amplifier

Operation panel

analog image data

(CCD OUT)

C2 C3

MCU PWB

Image process ASIC

image data

A/D

(CCDD0~7)

SRAM

32kbitx8

serial data

(OP DATA/KIN1/KIN2)

32kbitx8

SRAM

ROM

Image

process

image data(LD)

DRAM 16Mbit

(SC only)

CPU

RAM

(SC only)

BUS

Data select

DRAM 16Mbit

image data

image data (V DATA)

DRAM 16Mbit

(SC only)

serial data

CPU H8S

serial data (EEPD)

EEPROM

(SDATA)

ICU PWB (VIDEO)

ASIC

I/F

DRAM

image data

(Data1~8)

LSU unit

Laser

P3C4

1 – 4

3. Operations of each section

A. Paper feed, paper transport section

(1) Outline

The paper feed tray contains about 200 (250) sheets of paper. The paper is passed to the transfer section by the paper feed roller. The paper feed operation is controlled by the paper feed roller clutch

and the paper feed roller clutch solenoid. The paper feed clutch employs the mechanical spring clutch.

Paper mis-feed and paper jam are detected by the paper empty sensor and the paper entry sensor. The paper size (width) is detected by the paper size (width) detector to prevent toner from attaching to the area over the paper width.

(2) Major parts

1) PE SENSOR

19)

12)

9) PAPER SIZE SW

10)

11)

5) PUS

7) PIN SENSOR

13)

12)

13)

14)

16)

18)

15)

17)

19)

1 – 5

No.

1 PE SENSOR PEMP IN Paper empty

2 Paper guide Adjust the paper width. 3 Paper feed tray Sets the print paper. (Capacity:

4 Paper release

5 PUS PUS Paper feed clutch

6 Paper feed

7 PIN SENSOR PIN Paper in detector Photo

8 Paper feed roller Feeds paper. 9 PAPER SIZESWPAPER SIZEINPaper width

10 Paper pressure

11 Paper pressure

12 Paper separator Separates paper in paper feed

13 Paper feed clutch Mechanical

14 Paper feed clutch

15 Paper feed clutch

16 Paper feed clutch

17 Paper feed clutch

18 Paper feed clutch

19 Paper separater

Code Signal name Name Type Function/operation Active condition

detector

lever

solenoid

release lever

detector

plate

spring

lever

joint

sleeve

spring

gear

spring

Parts

Photo transmission sensor

transmission sensor

Mechanical switch (Micro switch)

spring type clutch

Detects paper on the paper tray. LOW (0V) when

XXX sheets) Put this lever straight to set

paper to release paper feed. Put this lever down to enable paper feed.

Controls (on/off) the main motor drive for the paper feed roller.

When the paper feed lever is put straight, this lever releases paper feed solenoid drive. This partially reduces stress to the paper feed roller clutch in removing paper.

Detects whether the fed paper is transported to the transfer position or not. By the timing of this detector signal, the relative positions of paper and print image are controlled.

Detects the paper width. This signal controls the laser beam radiation area.

Presses paper onto the paper feed roller.

operation. Controls ON/OFF of the paper

feed roller. (The paper feed roller is driven by the paper feed clutch solenoid and the main motor.

Driven by the paper feed clutch solenoid to control ON/OFF of the paper feed clutch. Prevents against reverse rotation of the paper feed roller.

Links the paper feed roller and the paper feed roller clutch.

Controls ON/OFF of the paper feed roller. (The paper feed roller is driven by the paper feed clutch solenoid and the main motor.)

Transmits the paper feed clutch rotation to the paper feed clutch sleeve.

Transmits the main motor power to the paper reed roller.

Applies a proper pressure to the paper separater.

Note

paper is detected.

LOW (0V) when paper is detected.

LOW (0V) when the max. width is detected.

1 – 6

(3) Operation

a. Block diagram

MCU(PCU)PWB

ASIC (IC8)

CPU (IC5)

PUS MEN

MMT0 MMT1

POUT-

+5V

1 2 3

CN7

+5V POUT GND

High voltage power PWB

+24V

Motor driver

+5V

PD801

PD802

Paper entry roller

Paper exit roller

CN805

12+24V

PUS

CN804

MA-

MB-

Paper pickup solenoid

Main motor

Paper feed roller

CN9

9PE

b. Operation

* The main motor is a 4-phase stepping motor of 2-phase excite-

ment bipolar system, which serves as the drive source of the paper feed and transport system.

* The pickup solenoid operates on 24V and turns ON/OFF paper

feed operation.

* The following sensors are used.

Paper empty sensor (transmission photo transistor):

It is installed on the LSU PWB and is used to detect whether there is paper in the paper feed tray or not.

Paper entry sensor (Transmission photo transistor):

This sensor is used to detect the paper feed timing of next paper (in pre-feed) and to make synchronization between paper transport and image forming on the drum. It is also used to detect a paper jam.

Paper exit sensor (Transmission photo transistor):

This sensor is used to detect that paper is discharged. It is also used to detect a paper jam.

LSU PWB

CN601

9PE

+24V

Paper empty

PD601

roller

* Paper release lever

(Paper release)

(Paper fixed)

The paper release lever is used to fix or release paper. To release paper, pull the lever toward you as shown in the figure below. To fix paper, push the lever forward. The lever mechanism is as shown below.

1 – 7

(Paper release operation)

Lower frame

Notch

Lock lever arm

Lock lever

Spring

(Paper fixing operation) When the paper release lever is pushed down, the paper release

lever arm pushes the lock lever arm in the direction of arrow (A). By the above operation, the rotating disk is lifted and the paper is

pushed by the paper feed roller. If printing is made without pushing down the paper release lever, the

lock lever arm is pushed by the paper feed roller gear boss in the direction of arrow (A) and the paper feed tray is pushed to fix the paper.

* Paper feed roller, paper feed solenoid

Paper feed tray

Paper release lever

Paper feed roller

Paper feed clutch

Clearance

The lock lever arm is always pressed onto the paper release lever by the sp ring. Wh en the paper re lease leve r is pul led toward you, th e lock lever arm is brought into contact with the lower frame so that the paper pressure plate is fixed at the paper release position. Under this condition, a clearance is provided between the paper feed roller and the paper feed tray as shown in the figure below, and the paper is released.

Paper release lever

Paper feed solenoid

Paper feed clutch

The paper feed solenoid is used to turn ON/OFF the paper feed clutch. When the paper feed solenoid is turned on, the paper feed roller is rotated.

Paper feed roller

Paper plessure plate

Paper release lever

Paper feed clutch

Paper feed roller gear

(A)

Sub release lever

Lock lever arm

paper feed clutch

The paper feed clutch is a spring clutch. The paper feed roller gear rotation is transmitted to the paper feed roller only in the direction of (A). That is, the paper feed roller is rotated only in the direction of (A) (paper feed direction).

1 – 8

Paper feed roller

Separate sheet

The paper feed roller is of circular form, and double paper feed is prevented by the separate sheet.

Paper feed clutch lever

B. Scanner (reading) section

(1) Outline

In this section, the copy lamp (Xenon lamp) radiates light onto a document, and the reflected light is detected by the image sensor (CCD element) to convert into electrical signals (analog signals), which are sent to the MCU PWB.

Clutch R sleeve

The paper feed clutch lever is provided to prevent the paper feed roller from rotating reversely. When paper feed is not performed, the paper feed clutch lever is engaged with the paper feed roller boss gear.

When removing paper for paper replacement, a reverse rotation power is applied to the paper feed roller. In this case, the paper feed solenoid provides enough power to prevent the paper feed roller from rotating reversely, however an excessive stress is applied to the spring clutch, which may be damaged. Therefore the paper feed clutch lever is used to lock and protect the spring clutch from an excessive stress.

1 – 9

+ 21 hidden pages