SERVICE MANUAL
CODE: 00ZAL840//B1E
BASIC MANUAL
DIGITAL COPIER
MODEL AL-800/840
CONTENTS
1. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
2. Outline of operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
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
for after sales service only.
The contents are subject to change without notice.
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SHARP CORPORATION
1. Block diagram
SCANNER (READING) SECTION
Control signal, detection signal,
drive signal, control data line
DOCUMENT
LENS
COPY LAMP
Image data signal line
SCANNER
MOTOR
MIRROR
CCD
LIGHT QUANTITY
SENSOR
SCANNER HOME
POSITION
Image (light)
SENSOR
Power line
COPY LAMP
CONTROL PWB
A/D
ONVERTOR
OPERATION PWB
LAMP (LED)
CPU
ASIC
MEMORY
ICU PWB
HOST(PC)
KEY
ASIC
MEMORY
FAN MOTOR
SCANNER (WRITE) SECTION
MCU (PCU) PWB
LASER
DIODO
LASER BEAM
SENSER
MOTOR
DRIVER
SCANNER
MOTOR
POLYGON
MIRROR
MAIN MOTOR
HIGH VOLTAGE POWER PWB
FUSING/PAPER EXIT SECTION
PAPER FEED SECTION
IMAGE PROCESS SECTION
PAPER FEED
ROLLER
CLUTCH
PAPER
FEED
ROLLER
TEMPERATURE
SENSOR
HEATER LAMP
MAIN
CHARGER
PAPER WIDTH
DETECTOR
DEVELOPING
ROLLER
PAPER
ROLLER
PHOTOCONDUCTOR
PRESSURE
ROLLER
PAPER
PRINT PWB
PAPER EMPTY
DETECTOR
PAPER
TRAY
PAPER
EXIT
ROLLER
SEPARATION
ELECTRODE
HEAT
ROLLER
TRANSFER
ROLLER
PAPER ENTRY
DETECTOR
PAPER EXIT
DETECTOR
TEMPERATURE
FUSE
AC POWER
POWER PWB
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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 trans-
ferred 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
1
3
2
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 resolu-
tion 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
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(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
C2
C3
ICU PWB
(VIDEO)
ASIC
I/F
image data
image data
(Data1~8)
MCU PWB
CCD PWB
CCD
Image process ASIC
DRAM
LSU unit
Laser
analog
image data
image data
A/D
(CCDD0~7)
Data select
image data(LD)
Image
process
Amplifier
image data (V DATA)
(CCD OUT)
DRAM
16Mbit
(SC only) (SC only) (SC only)
DRAM
DRAM
SRAM
32kbitx8
SRAM
32kbitx8
C1
16Mbit
16Mbit
C4
P3
serial data
(SDATA)
serial data
(OP DATA/KIN1/KIN2)
Operation panel
CPU
H8S
CPU
BUS
serial data (EEPD)
EEPROM
RAM
ROM
1 – 4
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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
2)
3)
1) PE SENSOR
9) PAPER SIZE SW
10)
11)
4)
4)
5) PUS
6)
8)
6)
7) PIN SENSOR
13)
12)
13)
14)
16)
16)
18)
19)
15)
8)
17)
12)
19)
1 – 5
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Parts
Type
Photo
transmission
sensor
No.
1
Note
Code
Signal name
Name
Function/operation
Active condition
PE SENSOR PEMP IN
Paper empty
detector
Detects paper on the paper tray. LOW (0V) when
paper is detected.
2
3
Paper guide
Adjust the paper width.
Paper feed tray
Sets the print paper. (Capacity:
XXX sheets)
4
Paper release
lever
Put this lever straight to set
paper to release paper feed. Put
this lever down to enable paper
feed.
5
6
PUS
PUS
Paper feed clutch
solenoid
Controls (on/off) the main motor
drive for the paper feed roller.
Paper feed
release lever
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.
7
PIN SENSOR PIN
Paper in detector Photo
sensor
Detects whether the fed paper is LOW (0V) when
transmission transported to the transfer
paper is detected.
position or not. By the timing of
this detector signal, the relative
positions of paper and print
image are controlled.
8
9
Paper feed roller
Feeds paper.
PAPER SIZE PAPER SIZE Paper width
Mechanical
Detects the paper width. This
switch (Micro signal controls the laser beam
LOW (0V) when
the max. width is
detected.
SW
IN
detector
switch)
radiation area.
10
11
12
13
Paper pressure
plate
Presses paper onto the paper
feed roller.
Paper pressure
spring
Presses paper onto the paper
feed roller.
Paper separator
Separates paper in paper feed
operation.
Paper feed clutch Mechanical
Controls ON/OFF of the paper
feed roller. (The paper feed roller
is driven by the paper feed clutch
solenoid and the main motor.
spring type
clutch
14
Paper feed clutch
lever
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.
15
16
Paper feed clutch
joint
Links the paper feed roller and
the paper feed roller clutch.
Paper feed clutch
sleeve
Controls ON/OFF of the paper
feed roller. (The paper feed roller
is driven by the paper feed clutch
solenoid and the main motor.)
17
Paper feed clutch
spring
Transmits the paper feed clutch
rotation to the paper feed clutch
sleeve.
18
19
Paper feed clutch
gear
Transmits the main motor power
to the paper reed roller.
Paper separater
spring
Applies a proper pressure to the
paper separater.
1 – 6
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(3) Operation
a. Block diagram
MCU(PCU)PWB
High voltage power PWB
+24V
CN805
1 +24V
2 PUS
ASIC
(IC8)
Paper pickup
solenoid
PUS
MEN
CN804
1
2
3
4
MA
MMT0
MMT1
MA-
MB
Motor
driver
Main motor
MB-
CPU
(IC5)
+5V
PIN
Paper entry
roller
Paper feed
roller
+5V
POUT-
CN7
1
2
3
+5V
Paper exit
roller
POUT
GND
PD802
LSU PWB
+24V
CN601
CN9
PE
Paper empty
roller
PE
9
PE
9
b. Operation
* Paper release lever
* 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.
(Paper release)
(Paper fixed)
* 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.
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
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(Paper release operation)
(Paper fixing operation)
Notch
When the paper release lever is pushed down, the paper release
lever arm pushes the lock lever arm in the direction of arrow (A).
Lower frame
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.
Lock lever arm
Lock lever
Spring
* Paper feed roller, paper feed solenoid
Paper feed solenoid
Paper feed tray
Paper release lever
Paper feed roller
Paper feed clutch
Paper feed clutch
Clearance
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.
The lock lever arm is always pressed onto the paper release lever by
the spring. When the paper release lever is pulled toward you, the
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.
ON
Paper release lever
Paper feed roller
Sub release lever
A
paper feed clutch
Paper plessure plate
Lock lever arm
(A)
Paper feed roller gear
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).
Paper release lever
Paper feed clutch
1 – 8
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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.
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
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
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(2) Major parts
10)
11)
1)
2)
4) MHPS
6) CCD SENSOR
8) SL SENSOR
5)
3)
2)
7)
OR
6) CCD SENS
4) MHPS
10)
8) SL SENSOR
7)
9)
11)
9)
5)
3)
Parts
Type
No.
Note
Code
Signal name
Name
Function/operation
Active condition
1
Scanner lamp
control PWB
Drives the scanner lamp.
Maintains the lamp light quantity
at a constant level.
2
3
Scanner drive wire
Transmits the scanner motor
power to the scanner unit.
Scanner motor
Drives the scanner unit.
4
MHPS
MHPS
Scanner home
position sensor
Photo
Detects the scanner home
HIGH (5V) when
the home position
is detected.
transmission position. By this signal the image
sensor
scanning operation is controlled.
5
6
Lens
Transfers the document image to
CCD.
CCD
SENSOR
CCD OUT
CCD (Image)
sensor
CCD
Scans the document images
(photo signals) and converts
them into electrical signals.
Digital signal
(8Bit)
7
8
Scanner lamp
Radiates light to the document to
allow the CCD to scan the
document images.
SL SENSOR PDA/PDK
Scanner lamp light Photo diode Detects the scanner lamp light
Analog signal
quantity sensor
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.
(0 ∼ 0.5V)
9
No. 1 mirror
No. 2 mirror
No. 3 mirror
Leads the document image to
CCD.
10
11
Leads the document image to
CCD.
Leads the document image to
CCD.
1 – 10
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(3) Operation
a. Wiring diagram
MCU(PCU) PWB
IC112
A/D
CCDD0
CCDD1
CCDD2
CCDD3
CCDD4
CCDD5
CCDD6
CCDD7
GND
A-GND
CCDOUT
A-GND
A5V
5V
12V
GND
f1
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
D-GND
A-GND
CCDOUT
A-GND
A5V
5V
12V
D-GND
f1
ASIC
IC8
5V
5V
12V
GND
f2
GND
SH-
GND
RS
GND
SP
GND
CP
GND
NC
10
11
12
13
14
15
16
17
18
19
20
21
22
10 D-GND
11 f2
12 D-GND
13 SH-
14 D-GND
15 RS
16 D-GND
17 SP
18 D-GND
19 CP
20 D-GND
21 NC
CCD UNIT
GND
22 D-GND
RAMP UNIT
CN2
CFL-H
CLCNT
1
2
3
4
5
6
7
FGND
PDA
PDK
INVERTER UNIT
CFL-L
CN10
CN1
1
2
3
4
24V
24V
1
2
3
4
P-GND
ON/OFF
PD
P-GND
CL-CNT
CL-IN
(Not used)
IC13
CPU
IC5
MRMT0
MRMT1
MRMT2
MRMT3
MRMT0
MRMT1
MRMT2
MRMT3
24V-mir
1
2
3
4
5
SCANER MOTOR
DRIVER
24V
MRPS1
MRPS2
1
2
3
GND
MHPS
5V
GND
MHPS
5V
1
2
3
MHPS
SCANER H.P
SENSOR
* Copy lamp
The copy lamp drive voltage corresponding to the sensor output level
(CLIN) is outputted.
A cathode ray tube (Xenon lamp) is used as the light source for
reading images.
The copy lamp is driven by the scanner lamp control PWB.
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.
1 – 11
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* CCD unit
* Scanner home position sensor
Images (light) is converted into an electrical signal (analog signal) by
the CCD.
The scanner home position sensor senses the scanner position. The
copy image position control is performed by the sensing timing of this
sensor.
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.
* Zooming
Zooming is performed by changing the copy magnification ratio in the
sub scanning direction or changing the scanning speed.
* Scanner motor
The scanner unit is driven by the scanner drive motor.
The copy magnification ratio in the main scanning direction is
changed by the software in the ASIC.
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 detect-
ing section. The major parts and their functions are described in the
following.
(2) Block diagram
Scanning motor drive signal (PMD, PMCLK)
No. 1
cylinder
lens
VIDEO
Laser diode
control circuit
Laser
diode
Collimator
lens
MCU
(PCU)
No. 2
reflection mirror
(curved mirror)
No. 1
reflection
mirror
SYNC
Laser beam
sensor
Motor
mirror
No. 2
cylinder
lens
No. 3
reflection
mirror
Drum
Signal
Laser beam
(3) Major parts
2)
1) SYNC
3)
8)
7)
4)
5)
6)
1 – 12
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Parts
Type
No.
1
Note
Code
Signal name
SYNC IN
Name
Function/operation
Active condition
SYNC
Laser beam sensor Bin diode
Detects the laser beam position.
By this signal the left image print
start position is controlled.
LOW (0V) when
laser beam is
detected.
2
3
No. 1 mirror
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.
5
6
7
8
Fθ mirror (No. 2
Corrects the laser beam form and
pitch.
mirror)
Scanning mirror
(rotation mirror)
Scans the laser beam and
performs imaging.
No. 1 cylindrical
lens
Adjust the direction of laser beam.
Laser diode
Generates laser beam. (Controls
ON/OFF for imaging)
(4) Operation
a. Wiring diagram
MCU(PCU) PWB
LSU PWB
IC603
Laser beam detection PWB
(start position detection PWB)
CPU
(IC5)
PMCLK
SAMP
+24V
CN9
CN603
3-termina
regulator
CN604
CN601
+24V
3
1
1
2
3
4
5
6
7
8
+24V
1
2
3
4
5
6
7
8
1
2
3
+5VL
SYNC_
GND
1
2
3
+5VL
SYNC_
GND
2
GND
GND
VDATA
SAMP
SYNC-
APCSTT
PMCLK
PMD-
VDATA
SAMP
SYNC-
APCSTT
PMCLK
PMD-
ASIC
(IC8)
LEND-
SYNC-
APCSTT
CN602
+24V
+24V
3
1
2
4
5
Scanning motor
PMD-
PMD-
+24V
VSYNC
PRSTT
PMCLK
GND
Q603
5
1
CN8
LD
/PD
4
3
GND
IC601
IM
CN203
VR601
SDATA
7
8
ASIC
LEND
+5VL
(IC202)
PRSTT
4
5
VSYNC
SYNC
3
2
GND
O/I
IC603
I/O
1
ICU PWB
b. Operation
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 photocon-
ductor drum by No. 1 cylinder lens and sent to the scanning mirror.
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.)
Rotation of the scanning mirror is controlled by the scanning motor to
scan laser beams.
1 – 13
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The scanning mirror is a 6-surface mirror. Six lines are printed for one
rotation of the scanning motor. Laser beams reflected by the scan-
ning 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 varia-
tions in the duplex scanning mirror installing angle, and leads the
stable laser beams for each line to the photoconductor drum.
Part name
Laser diode
Function
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
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.
No. 1 mirror
This mirror reflects laser beams to the
curved mirror.
Laser beam sensor
PWB (Start position
detection PWB)
Used to detect laser beams to make
horizontal synchronization.
The photo sensor on the PWB detects
laser beams to generate SYNC signal.
No. 2 mirror (Curved
mirror)
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.
No. 3 mirror
This mirror passes the laser beams
reflected from the curved mirror to the
photoconductor mirror.
No. 2 cylindrical lens
This lens is used to correct laser beam
deflection due to variations in the
scanning mirror angle.
D. Image process section
(1) Outline
This section is composed of the photoconductor section, the develop-
ing 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
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(2) Image forming process diagram
Scanning
Lens
Laser diode
High voltage
circuit
No. 1 -
No. 3 mirror
Main charger
Exposure
Toner
Cleaning, charging
Development,
residual toner
collection
High voltage
circuit
Discharging
brush
Discharging
Development
roller
High voltage
circuit
Paper exit
Separation
Fusing
Transfer
Paper feed roller
Paper tray
Paper
Separation
electrode
Transfer charger roller
High voltage circuit
Heat roller,
pressure roller
Heater lamp
The operation of this section are composed of the six processes:
charging, exposure, development, transfer, separation, and discharg-
ing. An OPC drum is used as the photocoductor drum. Toner is of
one-component. For charging, the rotation brush is used. For trans-
fer, 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
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(3) Major parts
a. Photoconductor section
1)
5)
6)
3)
5)
4)
2)
1)
Parts
No.
Note
Name
Type
Function/operation
Forms latent electrostatic images.
1
2
OPC drum
OPC
OPC drum earth electrode
Connects the OPC drum aluminum layer and
the earth (high voltage PWB).
3
4
Main charger electrode
Discharge brush
Connects the main charger output (high
voltage PWB) and the main charger brush.
Discharges (lower the potential of) the OPC
drum surface.
Japan only
5
6
Main charger brush
Toner seal
Charges the OPC drum.
Shield to prevent toner from leaking outside
the OPC drum unit.
1 – 16
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b. Development section
5)
2)
1)
7) 8) 5)
1)
3)
3)
6)
4)
4)
8)
5)
1)
Parts
No.
Note
Name
Type
Function/operation
1
Developing roller
Attaches toner to the latent electrostatic
images on the OPC drum to convert it into
a visible image.
2
3
4
5
6
Developing doctor
Controls toner quantity on the developing
roller and charges toner.
Developing bias
electrode
Connects the developing roller and the bias
voltage output (high voltage PWB).
Potential control
electrode
Connects the developing roller and the bias
voltage output (high voltage PWB).
Toner stirring roller
Lead toner to the developing roller and
charges toner.
Zenor diode
Maintains the potential between the
developing roller and the toner stirring roller
at a constant level.
7
8
Toner seal
Shields toner from leaking outside the
developing unit.
Potential control sheet
Maintains the developing roller potential at
a constant level.
1 – 17
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c. Transfer/separation section
1)
3)
4)
3)
5)
2)
1)
4)
Parts
No.
Note
Name
Function/operation
1
2
Transfer roller
Transfers toner images on the OPC drum onto the paper.
Transfer roller
electrode
Connects the transfer roller and the transfer voltage output (high voltage PWB).
3
Pressure spring
Applies pressure to the transfer roller, paper, and the OPC drum to improve
transfer efficiency.
4
5
Separation electrode Reduces paper charging potential to facilitate separation of paper.
Earth electrode
Connects the separation electrode and the earth (high voltage PWB).
1 – 18
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(4) System diagram
Laser
beam
Scanning mirror
Laser unit
MCU PWB
No. 1 - 4 mirror
Image data
Toner
High voltage power PWB
–310V/+200V
selection
DC 310V
–
Main
charger
brush
DC-310V
Developing
roller
DC +200V
Photoconductor drum
DC +3.5KV
AC600V(P-P)
DC-200V
Discharge
brush
DC –850V
Paper
Transfer
charger
roller
DC-850V
AC600V(P-P)
Separation
electrode
DC+500V
(5) Operation
a. Wiring diagram
MCU(PCU) PWB
CN6
3
2
1
GND
TSIN
TSIN
+5V
Toner sensor
High voltage power PWB
ASIC
(IC8)
Charger brush
MCON
Q804
MC
CB
T801
transformer
Discharge brush
OPC drum
+24VP
DRUM
EARTH
Driver I
C801
+24VP
Separation electrode
Transfer charger roller
TC/Bias ON
Q807
TC
Q806
T802
transformer
100V
Q803
Q808
DC
Bias
Supply roller
CPU
(IC5)
PWNSIN
Developing roller
Earth sheet
1 – 19
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b. Major parts functions and operations
<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
3)
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.
1)
11)
2)
4)
10)
9)
2) Doctor
The doctor is pressed onto the developing roller. It adjust the toner
quantity on the developing roller surface.
12)
The doctor is made of a conductive material.
3) Toner supply roller
5)
The toner supply roller transports toner to the developing roller.
4) Toner stirring plate
8)
7)
6)
The toner stirring plate stirs toner in the developing unit to transport
toner to the developing roller smoothly.
1
2
3
4
Developing
roller
5
6
7
8
Toner seal
9
Discharge
brush
5) Toner seal
The toner seal prevents toner from leaking outside the developing
unit.
Doctor
Transfer
charger roller
10 Main charger
brush
Toner stirring
plate
Separation
electrode
11 Toner seal
6) Discharge (Earth) sheet
The discharge sheet maintains the developing roller surface potential
at a constant level.
Toner supply
roller
Phot conductor
drum
12 Discharge
(Earth) sheet
<3> Transfer charger roller
<1> Photoconductor drum unit
The photoconductor surface is charged and latent electrostatic im-
ages are formed, then visible images are formed with toner.
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.
1) Photoconductor drum
Paper transported from the paper feed section is charged positively
and negatively charged toner on the OPC drum are transferred onto
the paper.
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.
During cleaning, a voltage of –850V is applied.
<4> Separation electrode
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.
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.
CTL
(Charge Transfer Layer)
OPC layer
<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.
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.
1 – 20
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c. Actual image forming process
Step 2 (Exposure); Laser beam scanning light corresponding to the
print data is radiated onto the OPC drum.
Step 1 (Cleaning, charging): Residual toner on the OPC drum is
stirred and negative charges are dis-
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.
tributed evenly on the OPC drum.
(The OPC drum is evenly charged.)
The main charger brush is of roller shape and is rotating.
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.
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 dis-
charge 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.
Laser beam
Main charger brush
Non-exposure area
Exposure area
CTL
CGL
Aluminum layer
(Drum base)
Residual toner
AC600V
(P-P)
OPC drum
DC-850V
Aluminum layer
(Drum base)
CTL
CGL
CTL
CGL
Aluminum layer
(Drum base)
1 – 21
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Step 3 (Development): Toner is attached to the latent electrostatic
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.
images formed on 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 develop-
ing roller.
In cleaning operation mode, DC +200V is applied to the developing
roller and cleaning capacity is further increased.
Step 4 (Transfer): Visible images of toner on the OPC drum are
transferred to the paper.
:Toner (Negative charge)
Doctor
Developing roller
Toner supply roller
100V
OPC drum
Exposure area
(Exposed by
laser beams.)
Earth sheet
Aluminum surface
(Drum base)
Non-exposure area
(Not exposed by
laser beams.)
CGL
OPC drum
CTL
DC
+200V
DC
-310V
Aluminum layer
(Drum base)
CGL
CTL
Paper
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 be-
cause 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:
Transfer roller
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).
DC+3500V
AC600V(P-P)
DC –850V
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
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The positive charges are attracted to the OPC drum which is nega-
tively charged, and put on the paper transported between the transfer
roller and the OPC drum. The paper, therefore, is charged positively.
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
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.
Step 7 (Cleaning): Residual toner on the OPC drum is removed.
In the cleaning mode, a voltage of –850 V is applied. If there is toner
Step 5 (Paper separation): Paper is separated from the OPC drum.
Main charger brush
Aluminum layer
(Drum base)
CGL
CTL
AC600V
(P-P)
Residual toner
Paper
OPC drum
DC-850V
Separation
electrode
Discharge brush
Aluminum layer
(Drum base)
CTL
CGL
Transfer roller
DC+500V
An electric force is acting between the paper which is positively
charged in the transfer process and the OPC drum which is negative-
ly charged. Positive charges on the paper are moved to the aluminum
layer through the separation electrode to reduce the potential dif-
ference between the OPC drum and the paper.
By this operation, the paper can be easily separated from the OPC
drum.
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
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d. OPC drum surface potential
<2> OPC drum surface potential and developing bias
voltage during developing
<1> OPC drum surface potential shift in printing
During developing
Start
End
Laser
beams
Dark area
potential
Dark area
potential
-850V
-310V
Developing
bias
-310V
Developing
bias
Toner attraction
potential
Light area potential
Time (OPC drum rotating angle)
Light area potential
Charging/
cleaning
Exposure Residual toner Transfer
collection/
Charging
Development
Time (OPC drum rotating angle)
1 – 24
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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)
9)
8)
7)
1)
6)
2) POUT
3)
4)
5)
4)
5)
9)
10)
9)
2) POUT
10)
1)
6)
11)
3)
Parts
Type
No.
1
MODEL
Note
Code Signal name
Name
Heat roller
Function/operation
Heats toner on the paper and LOW (0V) when
Active condition
fuses onto the paper.
paper is
detected.
2
3
4
5
6
POUT POUT IN
RTH IN
Paper exit detector Photo transmission Detects paper exit.
sensor
Fusing temperature Thermistor
sensor
Detects the heat roller
surface temperature.
Temperature fuse 1 Mold
(Fusing section)
Assures safety in overheating.
Temperature fuse 2 Mold
(Fusing section)
Assures safety in overheating.
Heats the heat roller.
HL
Heater lamp
Halogen lamp
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
9
Paper exit roller
Separation pawl
Discharges paper after fusing.
Separates paper from the
fusing roller mechanically.
Discharges paper outside the
machine after fusing.
10
11
Paper exit roller
Pressure spring
Applies a pressure to the
heat roller, paper, and
pressure roller to improve
transfer efficiency.
1 – 25
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(3) Operation
a. Wiring diagram
MCU(PCU) PWB
POWER SUPPLY PWB
Fusing section
AC POWER IN
Temperature fuse
(132 C)
CPU
(IC5)
CN603
1/3 HLL
HLON
HLON-
Gate
Temperature fuse
(187 C)
Heater
lamp
RTH
CN603
2/4 HLN
COMP
PR
Thermistor
AMP
CN2
1
2
GND
RTHN
ASIC
RTH
(IC202)
PR
CN801
+24V
DRIVER
1
2
+24V
NC
High voltage power PWB
3 +24VS
b. Operation
Heat roller:
The heat roller is made of aluminum
tube coated with teflon to provide a good
separation capability.
The heater lamp ON/OFF is controlled by the detection signal (volt-
age value) from the thermistor to maintain the heat roller surface
temperature at the optimum level.
Heater lamp:
Pressure roller:
Thermistor:
A halogen lamp is used as the heater
lamp.
The heat roller surface temperature is controlled to 160/155 ˚C in the
print mode and to 80 ˚C in the pre-heat mode.
Silicon rubber is used to provide enough
pressure.
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.
A chip-type thermistor of good response
is used to detect the heat roller surface
temperature.
The heater lamp is lighted by the AC power source.
Temperature fuse (132 ˚C): The temperature fuse (132 ˚C) is at-
tached to the fusing cover. When the
fusing cover ambient temperature be-
comes 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 abnor-
mally high, this fuse is blown off.
Separation pawl:
The separation pawl separates paper
from the heat roller mechanically.
1 – 26
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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)
Parts
No.
Note
Code
MM
Name
Main motor
Type
Function, operation
1
Stepping motor (+24V)
Drives the paper feed section, the paper
transport section, the fusing section, and
the image process section.
2
3
Paper feed section drive
gear
Transmits the main motor power to the
paper feed section.
Imaging process/
fusing section drive gear
Transmits the main motor power to the
imaging process section and the fusing
section.
(3) Wiring diagram
MCU(PCU)PWB
High voltage power PWB
Paper feed roller
ASIC
(IC8)
MEN
Heat roller
Pressure roller
Main motor
CN804
1
2
3
4
MA
Paper exit roller
MMT0
MMT1
MA-
MB
Motor
driver
Developing cartridge
MB-
CPU
(IC5)
Photoconductor cartridge
Transfer roller
1 – 27
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G. Electrical section
(1) Block diagram
ICU PWB
ASIC
I/F
MCU (PCU) PWB
Image process ASIC
CCD PWB
CCD
DRAM
CCD control
LSU unit
Laser
Data select
DRAM
Image
Amplifier
A/D
Laser beam
sensor
process
High voltage
PWB
Paper in sensor
Polygon motor
Paper exit
sensor
SRAM
32kX8
SRAM
32kX8
DRAM
16Mbit
DRAM
16Mbit 16Mbit
Pickup solenoid
Main motor
Motor driver
Scanner motor
FAN motor
CPU
H8S
Driver
Motor driver
Home position sensor
Operation panel PWB
Key switch
ROM
RAM
EEPROM
High voltage unit
Display lamp
Paper size sensor
Toner sensor
Developer cartridge
Heat roller
Thermistor
Transfer roller
Doctor
Scanner
Invertor
lamp
Main charger roller
Developing
roller
Power PWB unit
Heater lamp
Drum
OPC cartridge
Temperature
fuse
Earth sheet
Temperature
fuse
Control
electrode
Power SW
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 conver-
sion, 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 sig-
nals 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
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MCU PWB BLOCK DIAGRAM
HOME
POSITION
SENSOR
SCANNER
MOTOR
INVERTOR
PWB
CCD PWB
f1,f2,
SH-,RS,
SP,CP
MHPS_IN
CN12
MRMT0~3
CN11
CCDOUT
CLCNT
CN10
CN14
PAPER
SIZE
PSIZE_IN
IC13
IC112
SENSOR
VDATA
LASER
POLYGON
MOTOR
PMCLK
PMD-
LSU PWB
IC5
IC8
CPU
ASIC
H8S/2350
HG73C025FD
PAPER
EMPTY
SENSOR
PEMP_IN
PAPER
DSRDY-,RESERR-
DPAGE-,VIDEO
EXIT
PSIZE_IN
RTH_IN
SENSOR
ICU PWB
VSYNC-,PRSTT
RESET,DREADY-
DCRDY-,ERROR
SCLK,SYNC
THERMISTOR
CN1
CN4
CN5
CN6
MEN-,MMT0,1
MCON,HL,TC/BIASON
PUS,PR,PWMSIN
PIN_IN-
FW
OPCLK,OPLATCH
OPDATA,SELIN1,2,3OPKIN1,2
OPPSW
TS_IN
VFMOUT
TONER
SENSOR
OPERATION PANEL
FAN MOTOR
HIGH VOLTAGE PWB
ICU PWB
OPERATION PWB BLOCK DIAGRAM
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.
LAMP, VALUE DISPLAY LED
DISPLAY CONTROLLER (DRIVER)
IC901
ICU PWB
CN-901
MCU PWB
DECODER
IC902
CN202
TO PC
KEY SWITCH
MCU
PWB
IC202
GATE ARRAY
CN203
High voltage power PWB
IC201
DRAM
This PWB supplies the high voltage used in the image process sec-
tion. (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.
CN201
TO PC
Copy lamp control PWB
The copy lamp light quantity is controlled so that the necessary quan-
tity of light is provided even when conditions of the scanner (reading)
section are changed.
Operation PWB
Status data from the MCU PWB are converted into the lamp and
lamp display by the display controller. The key operations are con-
verted into key data signals and outputted to the MCU (PCU) PWB.
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
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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
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