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.)

4

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

23

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

P2

P1

CCD PWB

CCD

Amplifier

Operation panel

analog
image data

(CCD OUT)

C1

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

8)

8)

19)

12)

2)

3)

9) PAPER SIZE SW

10)

4)

11)

4)

5) PUS

6)

6)

7) PIN SENSOR

13)

12)

13)

14)

16)

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.

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

PIN

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

1

MA

2

MA-

3

MB

4

MB-

Paper pickup
solenoid

Main motor

Paper feed
roller

PE

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.

ON

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

A

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

(2) Major parts

4) MHPS

4) MHPS

10)

11)

8) SL SENSOR

2)

3)

1)

2)

6) CCD SENSOR

5)

7)

4) MHPS

10) 8) SL SENSOR 7) 6) CCD SENS

9)

11) 9) 5) 3)

No.

1 Scanner lamp

2 Scanner drive wire Transmits the scanner motor

3 Scanner motor Drives the scanner unit.
4 MHPS MHPS Scanner home

5 Lens Transfers the document image to

6 CCD

7 Scanner lamp Radiates light to the document to

8 SL SENSOR PDA/PDK Scanner lamp light

9 No. 1 mirror Leads the document image to

10 No. 2 mirror Leads the document image to

11 No. 3 mirror Leads the document image to

Code Signal name Name Type Function/operation Active condition

control PWB

position sensor

CCD OUT CCD (Image)

SENSOR

sensor

quantity sensor

Parts

Drives the scanner lamp.
Maintains the lamp light quantity
at a constant level.

power to the scanner unit.

Photo
transmission
sensor

CCD Scans the document images

Photo diode Detects the scanner lamp light

Detects the scanner home
position. By this signal the image
scanning operation is controlled.

CCD.

(photo signals) and converts
them into electrical signals.

allow the CCD to scan the
document images.

quantity. This signal is inputted to
the scanner lamp control PWB to
control the scanner lamp drive
voltage to maintain a constant
level of light quantity.

CCD.

CCD.

CCD.

OR

Note

HIGH (5V) when
the home position
is detected.

Digital signal
(8Bit)

Analog signal
(0 ∼ 0.5V)

1 – 10

(3) Operation

a. Wiring diagram

MCU(PCU) PWB

ASIC

IC8

CPU

IC5

CCDD0
CCDD1
CCDD2
CCDD3
CCDD4
CCDD5
CCDD6
CCDD7

CLCNT

MRMT0
MRMT1
MRMT2
MRMT3

IC112

A/D

(Not used)

IC13

DRIVER

12V

GND 1
A-GND 2
CCDOUT 3
A-GND 4

5V
5V

A5V 5
5V 6
12V 7
GND 8
f1 9
GND 10
f2 11
GND 12
SH- 13
GND 14
RS 15
GND 16
SP 17
GND 18
CP 19
GND 20
NC 21
GND 22

D-GND 1
A-GND 2
CCDOUT 3
A-GND 4
A5V 5
5V 6
12V 7
D-GND 8
f1 9
D-GND10
f211
D-GND12
SH-13
D-GND14
RS15
D-GND16
SP17
D-GND18
CP19
D-GND20
NC21
D-GND22

CCD UNIT

RAMP UNIT

CN2

CFL-H 1
2
3

FGND 4

PDA 5

24V

CN10

24V 1
P-GND 2
CL-CNT 3
CL-IN 4

MRMT0 1
MRMT1
MRMT2
MRMT3
24V-mir

PDK 6

CFL-L 7

CN1

24V 1

P-GND 2

ON/OFF 3

PD 4

2
3
4
5

SCANER MOTOR

INVERTER UNIT

MRPS1

MRPS2

MHPS

GND 1
MHPS 2
5V 3

* Copy lamp
A cathode ray tube (Xenon lamp) is used as the light source for

reading images.
To maintain the lamp light quantity at constant level, the following

operations are performed.
The copy lamp light quantity sensor is provided in the scanner unit to

detect the copy lamp light quantity.

GND 1

MHPS 2

5V 3

SCANER H.P
SENSOR

The copy lamp drive voltage corresponding to the sensor output level
(CLIN) is outputted.

The copy lamp is driven by the scanner lamp control PWB.

1 – 11

* CCD unit
Images (light) is converted into an electrical signal (analog signal) by

the CCD.
The image signal read by the CCD is converted into a digital signal b

the A/D convertor in the MCU PWB and outputted to the ASIC, where
the image is processed.

* Scanner motor
The scanner unit is driven by the scanner drive motor.

C. Scanner (writing) section

(1) Outline

In this section, the dot image data sent from the MCU PWB are
converted into laser beams (ON/OFF), which are scanned to form
latent electrostatic images on the OPC drum. It is composed of the
laser beam generating section (where dot image data signals are
converted into laser beams (ON/OFF)), the laser beam correction
section, the laser beam scanning section, and the laser beam detect­ing section. The major parts and their functions are described in the
following.

(2) Block diagram

Scanning motor drive signal (PMD, PMCLK)

* Scanner home position sensor
The scanner home position sensor senses the scanner position. The

copy image position control is performed by the sensing timing of this
sensor.

* Zooming
Zooming is performed by changing the copy magnification ratio in the

sub scanning direction or changing the scanning speed.
The copy magnification ratio in the main scanning direction is

changed by the software in the ASIC.

MCU

(PCU)

SYNC

Drum

control circuit

Laser beam
sensor

Laser diode

VIDEO

(3) Major parts

No. 2
cylinder
lens

No. 2
reflection mirror
(curved mirror)

No. 3
reflection
mirror

Signal

Laser beam

Laser
diode

Collimator
lens

No. 1
reflection
mirror

No. 1
cylinder
lens

Motor
mirror

2)

1) SYNC

3)

8)

1 – 12

7)

4)

6)

5)

No.

Code Signal name Name Type Function/operation Active condition

Parts

1 SYNC SYNC IN Laser beam sensor Bin diode Detects the laser beam position.

By this signal the left image print

start position is controlled.
2 No. 1 mirror
3 No. 3 mirror Leads the laser beam to the OPC

drum.
4 Second cylindrical

lens

Corrects the laser beam

deflection by variations in the

scanning mirror angle. Corrects

the optical section dirt.
5Fθ mirror (No. 2

mirror)

6 Scanning mirror

(rotation mirror)

7 No. 1 cylindrical

Corrects the laser beam form and

pitch.

Scans the laser beam and

performs imaging.

Adjust the direction of laser beam.

lens

8 Laser diode Generates laser beam. (Controls

ON/OFF for imaging)

(4) Operation

a. Wiring diagram

Note

LOW (0V) when
laser beam is
detected.

CPU
(IC5)

ASIC

(IC8)

ASIC

(IC202)

PMCLK

SAMP

LEND­SYNC­APCSTT

PMD-

VSYNC

PRSTT

SDATA
LEND
PRSTT

VSYNC
SYNC

MCU(PCU) PWB

ICU PWB

+24V

CN8

CN203

CN9
1
2
3
4
5
6

APCSTT
7
8

+24V
GND
VDATA
SAMP
SYNC-

PMCLK
PMD-

CN601
1
2
3
4
5
6
7
8

+24V
GND
VDATA
SAMP
SYNC-

APCSTT

PMCLK
PMD-

4

+5VL

3

GND

GND

LSU PWB

IC603

3-termina

31

regulator

2

+24V

Q603

5

1

INH

OUT

VPS

54

3

IM

VDD

2

O/I

IC601

VCC

78

CONT

IC603
I/O

1

CN603

+5VL

1
2

SYNC_

GND3

CN602

+24V

3
1

PMD-

2

+24V

4

PMCLK

5 GND

LD
/PD

VR601

Laser beam detection PWB
(start position detection PWB)

CN604

+5VL

1
2

SYNC_

GND3

Scanning motor

b. Operation

The APC circuit is started by the APCSTT signal sent from the MCU
(PCU) PWB, and laser diode is turned on/off according to the VIDEO
signal. (The laser diode is turned on when the VDATA signal is
HIGH.)

When the laser diode is turned on, 780nm infrared semiconductor
laser beams are radiated from the laser diode and arranged to be
parallel beams by the collimeter lens and focused to the photocon­ductor drum by No. 1 cylinder lens and sent to the scanning mirror.

Rotation of the scanning mirror is controlled by the scanning motor to
scan laser beams.

1 – 13

The scanning mirror is a 6-surface mirror. Six lines are printed for one
rotation of the scanning motor. Laser beams reflected by the scan­ning mirror are passed to the curved mirror by the No. 1 reflection
mirror. Before reaching the curved mirror, the laser beams enter the
laser beam sensor on the start position detection PWB to make
horizontal synchronization (generating SYNC signal).

The laser beams from No. 1 reflection mirror are arranged to be
parallel beams by the curved mirror and passed to No. 3 reflection
mirror. The laser beams reflected by No. 3 reflection mirror are
passed through No. 2 cylinder lens to the photoconductor drum.

No. 2 cylinder lens corrects deflection of laser beams due to varia­tions in the duplex scanning mirror installing angle, and leads the
stable laser beams for each line to the photoconductor drum.

Part name Function

Laser diode The laser power is controlled by the

APC (Auto Power Control) circuit. In
addition, the paper empty sensor is
provided.
The laser diode radiates 780nm infrared
semiconductor laser beams under
control of the laser control PWB.

Collimator lens The collimator lens arranges laser

beams radiated from the laser diode to
be parallel beams and converges them

on the photoconductor drum.
No. 1 cylindrical lens Adjusts the direction of the laser beams.
Scanning motor/

Scanning mirror

No. 1 mirror This mirror reflects laser beams to the

Laser beam sensor
PWB (Start position
detection PWB)

No. 2 mirror (Curved
mirror)

No. 3 mirror This mirror passes the laser beams

No. 2 cylindrical lens This lens is used to correct laser beam

Used to rotate the scanning mirror.

Started by the drive signal (PMD_) from

the PCU. The RPM is controlled by the

clock signal (PMCLK_). The motor RPM

is 11811 RPM.

The scanning mirror is a6-surface

mirror, and it reflects laser beams. By

this operation, 6 lines of printing is made

for one rotation of the scanning motor.

curved mirror.

Used to detect laser beams to make

horizontal synchronization.

The photo sensor on the PWB detects

laser beams to generate SYNC signal.

Laser beams are scanned by the

scanning mirror. But the dot interval of

laser beams radiated onto the

photoconductor differs at the center and

at the corners. This mirror corrects this

difference to provide even dot interval of

laser beams. For this reason, it is of

curved structure.

reflected from the curved mirror to the

photoconductor mirror.

deflection due to variations in the

scanning mirror angle.

D. Image process section

(1) Outline

This section is composed of the photoconductor section, the develop­ing section, the transfer/separation section. Images formed by laser
beams formed by the scanner (Writing) section are converted into a
latent electrostatic images, which are formed into visible images by
toner development. The toner images are transferred onto paper.

1 – 14

(2) Image forming process diagram

High voltage
circuit

Paper exit

High voltage
circuit

Main charger
brush

Discharging
brush

Fusing

Heat roller,
pressure roller

Cleaning, charging

Discharging

Separation

Separation
electrode

Scanning
mirror

No. 1 ­No. 3 mirror

Exposure

Transfer

Transfer charger roller

Lens

Development,
residual toner
collection

Paper feed roller

Laser diode

Toner

Development
roller

Paper tray

High voltage
circuit

Paper

High voltage circuit

Heater lamp

The operation of this section are composed of the six processes:
charging, exposure, development, transfer, separation, and discharg­ing. An OPC drum is used as the photocoductor drum. Toner is of
one-component. For charging, the rotation brush is used. For trans­fer, the roller is used and virtually no generation of ozone. It is also
compact. The high voltage required in this section is provided by the
high voltage power PWB.

1 – 15

(3) Major parts

a. Photoconductor section

1)

5)

6)

5)

4)

2)

1)

No.

1 OPC drum OPC Forms latent electrostatic images.
2 OPC drum earth electrode Connects the OPC drum aluminum layer and

3 Main charger electrode Connects the main charger output (high

4 Discharge brush Discharges (lower the potential of) the OPC

5 Main charger brush Charges the OPC drum.
6 Toner seal Shield to prevent toner from leaking outside

Name Type Function/operation

Parts

the earth (high voltage PWB).

voltage PWB) and the main charger brush.

drum surface.

the OPC drum unit.

3)

Note

Japan only

1 – 16

b. Development section

5)

2)

1)

5)

8)7)

3)

3)

4)

5)

1)

No.

1 Developing roller Attaches toner to the latent electrostatic

2 Developing doctor Controls toner quantity on the developing

3 Developing bias

electrode

4 Potential control

electrode

5 Toner stirring roller Lead toner to the developing roller and

6 Zenor diode Maintains the potential between the

7 Toner seal Shields toner from leaking outside the

8 Potential control sheet Maintains the developing roller potential at

Name Type Function/operation

Parts

images on the OPC drum to convert it into
a visible image.

roller and charges toner.
Connects the developing roller and the bias

voltage output (high voltage PWB).
Connects the developing roller and the bias

voltage output (high voltage PWB).

charges toner.

developing roller and the toner stirring roller
at a constant level.

developing unit.

a constant level.

1)

6)

4)

8)

Note

1 – 17

c. Transfer/separation section

3)

1)

4)

3)

2)

1)

No.

1 Transfer roller Transfers toner images on the OPC drum onto the paper.
2 Transfer roller

3 Pressure spring Applies pressure to the transfer roller, paper, and the OPC drum to improve

4 Separation electrode Reduces paper charging potential to facilitate separation of paper.
5 Earth electrode Connects the separation electrode and the earth (high voltage PWB).

Name Function/operation

Connects the transfer roller and the transfer voltage output (high voltage PWB).

electrode

transfer efficiency.

Parts

4)

5)

Note

1 – 18

(4) System diagram

Scanning mirror

Laser
beam

Laser unit

MCU PWB

Main
charger
brush

Discharge
brush

Separation
electrode

(5) Operation

a. Wiring diagram

No. 1 - 4 mirror

Photoconductor drum

Transfer
charger
roller

Developing
roller

DC-200V

Paper

Toner

DC-310V

Image data

High voltage power PWB

DC-850V
AC600V(P-P)

DC+500V

–

310V/+

200V

selection
DC

–

310V

DC +200V

DC +3.5KV
AC600V(P-P)

DC –850V

MCU(PCU) PWB

TSIN

ASIC
(IC8)

CPU
(IC5)

CN6

+5V

MCON

TC/Bias ON

PWNSIN

GND3
TSIN2

1

High voltage power PWB

Driver I

C801

Q803
Q808

Toner sensor

Q804

Q806

+24VP

+24VP

Q807

T801

transformer

T802

transformer

MC

CB

DRUM
EARTH

TC

DC
Bias

Charger brush

Discharge brush

OPC drum

Separation electrode

Transfer charger roller

100V

Supply roller

Developing roller

Earth sheet

1 – 19

b. Major parts functions and operations

11)

1)

10)

9)

5)

3)

2)

4)

12)

<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 develop­ing. 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.

8)

1 Developing

roller

2 Doctor 6 Transfer

3 Toner stirring

plate

4 Toner supply

roller

5 Toner seal 9 Discharge

charger roller

7 Separation

electrode

8 Phot conductor

drum

6)7)

brush

10 Main charger

brush

11 Toner seal

12 Discharge

(Earth) sheet

<1> Photoconductor drum unit

The photoconductor surface is charged and latent electrostatic im­ages 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 resis­tance 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

OPC layer

(Charge Transfer Layer)
CGL

(Charge Generation Layer)
Aluminum layer

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 dis­charges paper charged positively in the transfer section to reduce
potential difference with the OPC drum, reducing electrostatic attrac­tion 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.

2) Main charger brush

The main charger brush charges the OPC drum surface. It is com­posed 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 supply­ing 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.

1 – 20

c. Actual image forming process
Step 1 (Cleaning, charging): Residual toner on the OPC drum is

stirred and negative charges are dis­tributed evenly on the OPC drum.

(The OPC drum is evenly charged.)
The main charger brush is of roller shape and is rotating.
The main charger brush stirrs residual toner and paper dust on the

OPC drum.
At the same time, a high voltage of AC 600V (P-P) is applied to DC

–850V and applied to the main charger brush to make electric dis­charge between the roller and the OPC drum to form positive and
negative charges. The negative charges are attracted to the OPC
drum which is positively charged. And negative charges are evenly
distributed on the OPC drum. (The OPC drum surface is evenly
charged.)

Residual toner and paper dust stirred by the main charger brush are
distributed evenly on the OPC drum.

Step 2 (Exposure); Laser beam scanning light corresponding to the

print data is radiated onto the OPC drum.

Positive and negative charges are generated in the CGL of the OPC
drum which are radiated with laser beams. The positive charges in
the CGL are moved to the OPC drum surface, and the negative
charges are moved to the aluminum layer.

Therefore, positive and negative charges are neutralized in the OPC
drum exposed with laser beams and the aluminum layer, reducing the
OPC drum surface potential. On the other hand, there is no change in
the area which is not exposed with laser beams. So the OPC drum
surface is kept negatively charged to maintain a high potential. As a
result, latent electrostatic images are formed on the OPC drum.

AC600V
(P-P)

DC-850V

Residual toner

CTL

CGL

Main charger brush

OPC drum

Aluminum layer
(Drum base)

Non-exposure area

Laser beam

Exposure area

CTL

CGL

Aluminum layer
(Drum base)

CTL

CGL

Aluminum layer
(Drum base)

1 – 21

Step 3 (Development): Toner is attached to the latent electrostatic

images formed on the OPC drum.

At that time, the potential of the OPC drum surface where there is no
charge by exposure of laser beams is higher than the developing
roller potential. On the other hand, there are negative charges in the
OPC drum surface area which is not exposed to laser beams. When
that area is brought into contact with the developing roller, if toner is
attached to the OPC drum,. toner is moved to the developing roller
which is in a high potential than the OPC drum.

As a result, unnecessary toner and paper dust on the OPC drum are
collected in the developing unit.

In this operation, toner is moved from the OPC drum to the develop­ing roller.

In cleaning operation mode, DC +200V is applied to the developing
roller and cleaning capacity is further increased.

Doctor

Developing roller

OPC drum
Exposure area

(Exposed by
laser beams.)

Non-exposure area
(Not exposed by
laser beams.)

:Toner (Negative charge)

100V

Earth sheet

Toner supply roller

Step 4 (Transfer): Visible images of toner on the OPC drum are

transferred to the paper.

Aluminum surface
(Drum base)

OPC drum

CGL

CTL

Aluminum layer
(Drum base)

CGL

CTL

DC
+200V

DC

-310V

Toner enters between the developing roller and the doctor, and a thin
layer of toner (a certain fixed amount) is formed on the developing
roller by a pressure applied to the doctor.

Toner is negatively charged by friction when passing between the
developing roller and the doctor.

When the OPC drum surface area where there is no charges be­cause of exposure of laser beams is brought into contact with the
developing roller, toner is moved from the developing roller to the
OPC drum surface. The principle of the process is as follows:

A bias voltage of –310V is applied to the developing roller. Toner
which is charged by potential difference between the bias voltage and
the OPC drum surface potential is attracted to the OPC drum surface
(positively charged).

A high voltage of AC60V (P-P) is applied to DC+350V and applied to
the transfer roller, generating electric discharge between the roller
and the OPC drum, generating positive and negative charges.

1 – 22

Paper

Transfer roller

DC+3500V
AC600V(P-P)

DC –850V

The positive charges are attracted to the OPC drum which is nega­tively charged, and put on the paper transported between the transfer
roller and the OPC drum. The paper, therefore, is charged positively.

The negative charged toner on the OPC drum is attracted to the
paper which is positively charged and visible images of toner are
transferred onto the paper.

In the cleaning mode, a voltage of –850 V is applied. If there is toner
on the transfer roller, the toner is attracted to the OPC drum.

Step 5 (Paper separation): Paper is separated from the OPC drum.

Step 6 (Discharging): The drum surface is discharged by the dis-

charge brush to facilitate cleaning. (Residual
toner can be easily collected by the main
charger roller.)

Step 7 (Cleaning): Residual toner on the OPC drum is removed.

Aluminum layer
(Drum base)

CGL

CTL

Paper

Separation
electrode

Transfer roller

An electric force is acting between the paper which is positively
charged in the transfer process and the OPC drum which is negative­ly charged. Positive charges on the paper are moved to the aluminum
layer through the separation electrode to reduce the potential dif­ference between the OPC drum and the paper.

By this operation, the paper can be easily separated from the OPC
drum.

Main charger brush

AC600V
(P-P)

Residual toner

OPC drum

DC-850V

Discharge brush

CTL

DC+500V

CGL

Aluminum layer
(Drum base)

The main charger brush is of roller shape and is rotating.
The main charger brush stirs residual toner and paper dust on the

OPC drum. The residual toner and paper dust are evenly distributed
and put on the OPC drum again to be sent to the developing roller.

1 – 23

d. OPC drum surface potential

<1> OPC drum surface potential shift in printing

<2> OPC drum surface potential and developing bias

voltage during developing

-310V

-850V

OPC drum surface potential (-V)

Charging/
cleaning

Laser
beams

Exposure

Dark area
potential

Toner attraction
potential

Light area potential

Residual toner
collection/
Development

Time (OPC drum rotating angle)

Transfer

Developing
bias

Charging

-310V

OPC drum surface potential (-V)

Start

Light area potential

Time (OPC drum rotating angle)

During developing

Dark area
potential

Developing
bias

End

1 – 24

E. Fusing/paper exit section

(1) Outline

Toner attracted to the paper in the transfer section is fused by heat
and pressure of the heat roller. The heat roller is of thin aluminum
roller which is high heat conductivity, minimizing the warm up time.
The heat roller surface temperature is detected by the fusing
temperature sensor to maintain the fusing temperature at a constant
level (160/155 ˚C).

(2) Major parts

11)

7)

11)

8)

8)

6)

2) POUT

3)

4)

5)

4) 5)

2) POUT

3)

No.

Code Signal name Name Type Function/operation Active condition

6)

Parts

9)

10)

9)

10)

1 Heat roller Heats toner on the paper and

fuses onto the paper.

7)

1)

9)

1)

11)

MODEL Note

LOW (0V) when
paper is
detected.

2 POUT POUT IN Paper exit detector Photo transmission

Detects paper exit.

sensor

3 RTH IN Fusing temperature

sensor

4 Temperature fuse 1

Thermistor Detects the heat roller

surface temperature.

Mold Assures safety in overheating.

(Fusing section)

5 Temperature fuse 2

Mold Assures safety in overheating.

(Fusing section)

6 HL Heater lamp Halogen lamp Heats the heat roller. 100V series 10V 500W

120V series 120V 500W
200V series 230V 500W

7 Pressure roller Applies a pressure to the

heat roller and paper to

improve fusing efficiency.
8 Paper exit roller Discharges paper after fusing.
9 Separation pawl Separates paper from the

fusing roller mechanically.

10 Paper exit roller Discharges paper outside the

machine after fusing.

11 Pressure spring Applies a pressure to the

heat roller, paper, and

pressure roller to improve

transfer efficiency.

1 – 25

(3) Operation

a. Wiring diagram

CPU

(IC5)

ASIC

(IC202)

MCU(PCU) PWB POWER SUPPLY PWB

AC POWER IN

HLON

Gate

RTH

AMP

PR

DRIVER

HLON-

COMP

CN2
GND

RTHN

High voltage power PWB

PR

1
2

+24V

CN801

1

+24V

2

NC

3 +24VS

CN603

1/3

CN603

2/4

Fusing section

Temperature fuse
(132 C)

HLL

HLN

RTH

Temperature fuse
(187 C)

Heater

lamp

Thermistor

b. Operation

The heater lamp ON/OFF is controlled by the detection signal (volt­age value) from the thermistor to maintain the heat roller surface
temperature at the optimum level.

The heat roller surface temperature is controlled to 160/155 ˚C in the
print mode and to 80 ˚C in the pre-heat mode.

As a protective measure in case of abnormally high temperature in
the fusing section, two temperature fuses are provided in the heater
lamp power line.

The heater lamp is lighted by the AC power source.

Heat roller: The heat roller is made of aluminum

tube coated with teflon to provide a good
separation capability.

Heater lamp: A halogen lamp is used as the heater

lamp.

Pressure roller: Silicon rubber is used to provide enough

pressure.

Thermistor: A chip-type thermistor of good response

is used to detect the heat roller surface
temperature.

Temperature fuse (132 ˚C): The temperature fuse (132 ˚C) is at-

tached to the fusing cover. When the
fusing cover ambient temperature be­comes abnormally high, this fuse is
blown off.

Temperature fuse (187 ˚C): The temperature fuse (187 ˚C) is closely

attached to the heat roller. When the
heat roller temperature becomes abnor­mally high, this fuse is blown off.

Separation pawl: The separation pawl separates paper

from the heat roller mechanically.

1 – 26

F. Drive section

(1) Outline

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 in the high voltage power PWB.

(2) Major parts

1)

3)

2)

No.

Code Name Type Function, operation

1 MM Main motor Stepping motor (+24V) Drives the paper feed section, the paper

2 Paper feed section drive

gear

3 Imaging process/

fusing section drive gear

Parts

transport section, the fusing section, and
the image process section.

Transmits the main motor power to the
paper feed section.

Transmits the main motor power to the
imaging process section and the fusing
section.

(3) Wiring diagram

MCU(PCU)PWB

ASIC
(IC8)

CPU
(IC5)

MEN

MMT0
MMT1

High voltage power PWB

CN804

1

Motor
driver

2
3
4

Main motor

MA
MA­MB
MB-

Note

Paper feed roller

Heat roller
Pressure roller

Paper exit roller

Developing cartridge

Photoconductor cartridge

1 – 27

Transfer roller

G. Electrical section

(1) Block diagram

CCD PWB

CCD

Amplifier

Scanner motor

FAN motor

Home position sensor

Operation panel PWB

Key switch
Display lamp

Paper size sensor

Toner sensor

Scanner

lamp

Invertor

MCU (PCU) PWB

Power PWB unit

Temperature

Power SW

A/D

SRAM
32kX8

fuse

Motor driver

Image process ASIC

CCD control

Image

process

SRAM
32kX8

Heat roller

Thermistor

Heater lamp

Temperature

DRAM
16Mbit

fuse

RAMROM

DRAM
16Mbit

Data select

DRAM
16Mbit

CPU
H8S

EEPROM

Developer cartridge

Doctor

Developing

roller

Earth sheet

ICU PWB

ASIC

I/F

DRAM

Paper in sensor

Driver

Motor driver

High voltage unit

OPC cartridge

High voltage

PWB

Main charger roller

Drum

Control

electrode

LSU unit

Laser

Paper exit

sensor

Pickup solenoid

Main motor

Transfer roller

Laser beam

sensor

Polygon motor

a. Major sections operations and functions
MCU (PCU) PWB

The CPU controls the engine, and the ASIC performs image process.
Image data (analog signals) from the scanner (reading) section are
converted into digital signals by the A/D convertor and image process
(area separation, filter process, gamma correction, resolution conver­sion, zooming) is performed by the ASIC and the line memory
(SRAM). The processed data are outputted to the scanner (writing)
section.

During printing, the dot image data from the ICU PWB are received
and outputted to the scanner (writing) section straightly. The CPU
controls the machine operations according to the key operation sig­nals from the operation PWB. The loads (motor, lamp. solenoid, high
voltage power PWB, etc.) are controlled according to the sensors and
detectors signals. At the same time, the machine status data are
outputted to the operation section and the ICU PWB.

1 – 28

MCU PWB BLOCK DIAGRAM

PAPER

EXIT

SENSOR

THERMISTOR

PSIZE_IN

RTH_IN

CN7

CN2

OPCLK,OPLATCH

OPDATA,SELIN1,2,3

SCANNER

MOTOR

MRMT0~3

OPPSW

OPKIN1,2

OPERATION PANEL

HOME

POSITION

SENSOR

MHPS_IN

CN11 CN12 CN14

IC13

IC5

CPU

H8S/2350

CN4CN1

VFMOUT

FAN MOTOR

CCD PWB

f1,f2,

SH-,RS,

SP,CP

IC112

IC8

ASIC

HG73C025FD

MEN-,MMT0,1

MCON,HL,TC/BIASON

PUS,PR,PWMSIN

HIGH VOLTAGE PWB

CCDOUT

CN5

INVERTOR

PWB

CLCNT

CN10

PIN_IN-

FW

CN6

TS_IN

TONER

SENSOR

PSIZE_IN

CN13CN9CN8

DSRDY-,RESERR-

RESET,DREADY-

PAPER

SIZE

SENSOR

LSU PWB

DPAGE-,VIDEO
VSYNC-,PRSTT
DCRDY-,ERROR

SCLK,SYNC

VDATA

PMCLK

PMD-

PEMP_IN

ICU PWB

LASER

POLYGON

MOTOR

PAPER
EMPTY

SENSOR

ICU PWB

Print data from the host (PC) are developed by the ASIC and the line
memory (DRAM) to converted into full dot image data, which are then
outputted to the data select section in the MCU PWB. The machine
status data from the MCU PWB are outputted tot he host (PC). In
addition. the ASIC controls the parallel I/F.

ICU PWB

CN202

TO PC

MCU
PWB

CN203

IC202

GATE ARRAY

IC201

DRAM

CN201

TO PC

Operation PWB

Status data from the MCU PWB are converted into the lamp and
lamp display by the display controller. The key operations are con­verted into key data signals and outputted to the MCU (PCU) PWB.

OPERATION PWB BLOCK DIAGRAM

LAMP, VALUE DISPLAY LED

MCU PWB

DISPLAY CONTROLLER (DRIVER)

CN-901

IC901

DECODER

IC902

KEY SWITCH

High voltage power PWB

This PWB supplies the high voltage used in the image process sec­tion. (Main charger, developing bias, transfer charger) It also includes
the driver for the main motor. The power output is controlled by the
control signals from the MCU (PCU) PWB.

Copy lamp control PWB

The copy lamp light quantity is controlled so that the necessary quan­tity of light is provided even when 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. Control is made
with the control signals from the MCU (PCU) PWB.

Power PWB

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

1 – 29

q

COPYRIGHT  1998 BY SHARP CORPORATION

All rights reserved.

Printed in Japan.

No part of this publication may be reproduced,

stored in a retrieval system, or transmitted.

In any form or by any means,

electronic, mechanical, photocopying, recording, or otherwise,

without prior written permission of the publisher.

SHARP CORPORATION
Printing Reprographic Systems Group
Quality & Reliability Control Center
Yamatokoriyama, Nara 639-1186, Japan

1998 October Printed in Japan S