OKI 8c Maintenance Manual
OKIPAGE8c
LED Page Printer
ODA/OEL/INT
1997.11.19
MAINTENANCE
MANUAL
PREFACE
This maintenance manual provides procedures and techniques for the troubleshooting, maintenance, and
repair of OKIPAGE 8c.
This manual is written for maintenance personnel, but it should always be accompanied with the OKIPAGE
6c User’s Manual for procedures for handling and operating OKIPAGE 8c, For repairing each component
of OKIPAGE 8c, see the Troubleshooting manual.
[Notices]
The contents of this manual is subject to change without prior notice.
Although reasonable efforts have been taken in the preparation of this manual to assure its accuracy, this
manual may still contain any errors and omissions. OKI will not be liable for any damage caused or alleged
to be caused, by the customer or any other person using this maintenance manual to repair, modify, or
alter OKIPAGE 8c in any manner.
[Warning]
Many parts of OKIPAGE 8c are very sensitive and can be easily damaged by improper servicing. We
strongly suggest that OKIPAGE 8c be serviced by OKI’s authorized technical service engineers.
CONTENTS
1. SPECIFICATIONS ....................................................................................... 1-1
1.1 Basic System Configuration .......................................................................................1-1
1.2 Printer Specifications ................................................................................................. 1-2
1.3 Option Specifications ................................................................................................. 1-3
1.4 Basic Specifications ...................................................................................................1-4
2. OPERATION................................................................................................ 2-1
2.1 Main Control Board (PCR PCB)................................................................................. 2-2
2.2 Engine Control Board (PX4 PCB) ..............................................................................2-5
2.3 Power/Board .............................................................................................................. 2-6
2.4 Mechanical Processes ...............................................................................................2-7
2.4.1 Electrophotographic processing mechanism ................................................2-8
2.4.2 Paper running process ................................................................................. 2-14
2.5 Sensors...................................................................................................................... 2-23
2.5.1 Paper related sensors .................................................................................. 2-23
2.5.2 Other sensors ............................................................................................... 2-24
2.6 Correction of Color Deviation ..................................................................................... 2-25
2.7 Transfer Control according to Environmental Changes
(Room Temperatures and Relative Humidities)......................................................... 2-25
2.8 Form Jam Detection................................................................................................... 2-26
2.9 Cover Opening........................................................................................................... 2-26
2.10 Toner Low Detection.................................................................................................. 2-27
2.11 Page Size Detection .................................................................................................. 2-28
2.12 Power-on Processing................................................................................................. 2-29
2.12.1 Self-diagnostic test .......................................................................................2-29
3. PARTS REPLACEMENT............................................................................. 3-1
3.1 Precautions for Parts Replacement ........................................................................... 3-1
3.2 Parts Layout............................................................................................................... 3-3
3.3 How to Change Parts................................................................................................. 3-7
3.3.1 Cover Assy Rear .......................................................................................... 3-8
3.3.2 Motor -Fan (80-25) ....................................................................................... 3-9
3.3.3 Paper Eject Assy .......................................................................................... 3-10
3.3.4 Cover Assy Stacker, Guide Eject FD Assy ...................................................3-11
3.3.5 Frame Assy Upper........................................................................................ 3-12
3.3.6 Plate Support Assy ....................................................................................... 3-13
3.3.7 Limmiter 2way (L), (R)/Plate Guide (L), (R) ..................................................3-14
3.3.8 Cover ............................................................................................................ 3-15
3.3.9 PCB Assy : PCR ...........................................................................................3-16
3.3.10 Motor Fan (CU)............................................................................................. 3-17
3.3.11 PXF PCB/PX4 PCB ...................................................................................... 3-18
3.3.12 Gear Heat Assy ............................................................................................3-19
3.3.13 Main Motor (A), (B)Assy ............................................................................... 3-20
3.3.14 Gear One-way (Z30)..................................................................................... 3-21
3.3.15 Motor Assy BT .............................................................................................. 3-22
3.3.16 Power Supply Unit, Holder Inlet, Sheet Insuration ....................................... 3-23
3.3.17 Sensor Assy Box Toner ................................................................................ 3-24
3.3.18 Square-shaped Connector ........................................................................... 3-25
3.3.19 Hopping Motor.............................................................................................. 3-26
3.3.20 Gear One-way .............................................................................................. 3-27
3.3.21 Feeder Unit Front ......................................................................................... 3-28
3.3.22 Mannual Feed Hopper Assy......................................................................... 3-29
3.3.23 Guide Paper Input Assy................................................................................3-30
3.3.24 Lever Input Sensor ....................................................................................... 3-31
3.3.25 Roller Registration, Roller Assy Hopping ..................................................... 3-32
3.3.26 Roller Hopping.............................................................................................. 3-33
3.3.27 PXU PCB/PXM PCB, Lever Regist Sensor ..................................................3-34
3.3.28 Paper End Lever...........................................................................................3-35
3.3.29 PCO PCB (Operator Panel).......................................................................... 3-36
3.3.30 Holder Gear Toner Assy............................................................................... 3-37
3.3.31 Plate Latch Lever (FD), Spring Latch Lever (FD) ......................................... 3-38
3.3.32 Belt Cassette Assy ....................................................................................... 3-39
3.3.33 High Voltage Power Supply Unit, Bracket HV (BT) Assy ............................. 3-40
3.3.34 Eraser Bracket Assy, Eraser Bracket(KCM) Assy........................................ 3-41
3.3.35 Shaft Link...................................................................................................... 3-42
3.3.36 Contact (BL-R) Assy, Contact (CL-R) Assy.................................................. 3-43
3.3.37 Contact (BL-L) Assy, Contact (CL-L) Assy................................................... 3-44
3.3.38 Contact SB Assy........................................................................................... 3-45
3.3.39 PXC PCB...................................................................................................... 3-46
3.3.40 Heat Unit Assy.............................................................................................. 3-47
3.3.41 Oil Roller Assy.............................................................................................. 3-48
3.3.42 Lever Lock Heat (L) / (R), Guide Side Heat, Spring Lock............................. 3-49
3.3.43 PXL PCB ...................................................................................................... 3-50
3.3.44 Heat Unit Guide Assy ................................................................................... 3-51
3.3.45 Holder LED Assy, LED Head........................................................................ 3-52
4. ADJUSTMENTS .......................................................................................... 4-1
4.1 Maintenance Modes and Their Functions.................................................................. 4-1
4.1.1 User maintenance mode .............................................................................. 4-1
4.1.2 System maintenance mode.......................................................................... 4-5
4.1.3 Engine maintenance mode........................................................................... 4-7
4.2 Adjustments after Parts Replacement ....................................................................... 4-10
4.2.1 Setting the LED head driving time................................................................ 4-10
4.2.2 Color deviation correction............................................................................. 4-12
5. PERIODIC MAINTENANCE ........................................................................ 5-1
5.1 Periodically Replaced Parts .......................................................................................5-1
5.2 Cleaning..................................................................................................................... 5-1
5.3 Cleaning the LED Lens Array ....................................................................................5-1
5.4 Cleaning the Pickup Roller......................................................................................... 5-1
6. TROUBLESHOOTING PROCEDURES ...................................................... 6-1
6.1 Troubleshooting Tips .................................................................................................6-1
6.2 Points to Check before Correcting Image Problems.................................................. 6-1
6.3 Tips for Correcting Image Problems .......................................................................... 6-1
6.4 Preparation for Troubleshooting ................................................................................ 6-2
6.5 Troubleshooting Flow................................................................................................. 6-2
6.5.1 LCD status message/trouble list ...................................................................6-2
6.5.2 LCD message troubleshooting .....................................................................6-14
6.5.3 Image troubleshooting .................................................................................. 6-27
7. WIRING DIAGRAM..................................................................................... 7-1
7.1 Resistance Check ......................................................................................................7-1
7.2 Program/Font ROM Location .....................................................................................7-5
8. PARTS LIST ................................................................................................ 8-1
Appendix A ....................................................................................................... A-1
Appendix B ....................................................................................................... B-1
Appendix C ....................................................................................................... C-1
1. SPECIFICATIONS
M M M
M M
M
M M
LED head
Discharging indicators
Centronics
interface
OKI HSP
Controller
Junction board
Pulse motors
Engine controller
Low-voltage
power unit
Fixing unit
High-voltage
power unit
Second tray
Belt unit
<Sensors, switches, and thermistors>
Paper width sensor
Form size detector (4 bits)
Form end sensor
FF form end
FF home switch
Form feed sensor 1
Form feed sensor 2
Write sensor
Ejection sensor
Toner Low (Y.M.C.K)
EP Up/Down (Y.M.C.K)
Waste toner sensor
Resist Up/Down
Cover open switch (High-voltage
interlock switch)
Heater temperature thermistor
Backup temperature thermistor
Environment temperature sensor
Environment humidity sensor
Oil Roller switch
Fixing unit interlock switch
Waste toner box switch
Y-EP unit M-EP unit C-EP unit B-EP unit
PSIMM
x2
interface
SIMM
x2
interface
Y EP M EP C EP K EP BELT HEATER REGIST FF
Operator panel
1. SPECIFICATIONS
1.1 Basic System Configuration
The basic system configuration of OKIPAGE 8c is illustrated in Figure 1.1.
Figure 1.1
1 - 1
1.2 Printer Specifications
This printer unit is composed with the following hardware.
• Electro-photographric processor
• Paper feeder
• Controller (Cu part / PU Part)
• Operator panel
• Power board (High voltage part / PU part)
Figure 1-2 show the printer unit configuration.
Face-up Stacker Assy
Stacker Cover Assy
Rear Cover
Side Cover (L) Assy
Base Unit
Figure 1.2
I/F Cover Assy
Operator Panel Assy
1 - 2
1.3 Option Specifications
Options available for OKIPAGE 6c are as follows.
(1) 2nd-Feeder
(2) RAM SIMM module (72 pin SIMM, 4MB/8MB/16MB/32MB)
* Make sure to use a set of 2 of the same volume size modules.
(3) PS SIMM modules (72 pin)
1 - 3
1.4 Basic Specifications
(1) Dimensions
Width: 18.8" (478mm) Length: 24.5" (622mm) Height: 14.8" (375mm)
(2) Weight
45kg (100lbs)
(3) Form
Type: Ordinary paper and OHP (Only CG3710)
Sizes: Letter, Legal (13"or 14"), Executive, A4, A5, B5, and A6 (1st tray and front feeder)
Reams: 1st tray 16lbs to 28lbs
2nd tray 20lbs to 28lbs
Front feeder 16lbs to 32lbs
(5) Printing speed
8 pages per minute (OHP: 6 pages per minute)
(6) Resolution
600 dots per inch x 600 dots per inch
(7) Input voltage
120VAC +5.5%, -15%
230VAC to 240VAC +10%, -14%
(8) Power consumption
Peak: Typical operation
Idle: Power-save mode
(9) Frequency
50Hz or 60Hz +2%, -2%
(10) Noises
Operating: 50dB
Standby: 45dB
Power-saving: 43dB
(11) Expendibles and service life
Toner cartridge: 1500 pages (5% duty) (each of Y, M, C, and K)
Image drum: 10,000 pages (5% duty, continuous) (each of Y, M, C, and K)
Maintenance Kit: 7,500 (A4) pages (12 toner cartridges in total) (5% duty,
[Box Toner Assy + Holder 50% color printing and 50% monochromatic printing)
Assy Oil Roller]
(12) Periodically-replaced parts
Heat Unit Assy: 50,000 pages
Belt Cassette Assy: 50,000 pages
1 - 4
(13) Temperatures and relative humidities
Temperature
Temperature conditions
Temperature (in _F) Temperature (in _C) Remarks
Operating
Non-operating
Storage (1 year max.)
Delivery (1 month max.)
Delivery (1 month max.)
50 to 89.6
32 to 109.4
-14 to 109.4
-20 to 158
-20 to 122
Humidity
Humidity condition
Relative humidity (%) Wet-bulb temperature Remarks
Operating
Non-operating
Storage
Delivery
20 to 80
10 to 90
10 to 90
10 to 90
for the packed unit only
10 to 32
0 to 43
-10 to 43
-29 to 70
-29 to 50
25
26.8
35
40
17_C to 27_C (for assurance
of full-color printout quality)
Power off
with drum and toner
with drum and no toner
with drum and toner
50% to 70% (for assurance of
full-color printout quality)
Power off
(14) Printer life
3,000,000 (A4) pages or 5 years
1 - 5
2. OPERATION DESCRIPTION
2. OPERATION
AC-IN AC switch
Crimp-style terminal
PXL board
PXL
Ejection sensor
LED head: Y M C K
Discharging lamp: Y M C K
Heat roller
thermistor
Backup roller
thermistor
Heater unit
SUMi card x 4
PD6 board
Y600 14P
YPOW 12P
M600 14P
MPOW 12P
C600 14P
CPOW 12P
K600 14P
KPOW 12P
HEAD1 13P HEAD2 14P HEADPOW 12P HEAD3 15P
FF form
sensor
Toner sensor x 4
ID sensor x 4
Low-voltage power supply
6P
6P'
JST3P
FAN 1
FAN 2
3P
Oil PAD MSW
FF
motor
Paper supply sensor board
FF Pos MSW
PXM board
40095001YU
REG.POS
sensor
Resist
motor
Y-IDU
motor
M-IDU
motor
C-IDU
motor
K-IDU
motor
Belt
motor
Heat
motor
PXF board
JODEN 8P
FSENS 8P
TONER
14P
PXFIF 30P
OPTION 7P
PENDTNR 6P
PX4 board
2nd tray
(option)
Form end
sensor
Waste toner
sensor
YIDREG
8P
MCKID
12P
HETBELT
8P
HEAD3
15P
HEAD2
14P
HEAD1
13P
HEADPOW
12P
FF 12P
PXFIF 30P
HVOLT 16P COVOPN 2P PSIZE 6P
High-voltage power supply
PXC board
Form size detector
Cover open
MSW
PCR
Operator
panel
PCO
board
CM
6P
PU 40P
72PX2
PS SIMM
72PX2
D-RAM SIMM
64P
OKI HSP
36P
Paralle
CUIF 40P
POWER 30P
THE.RM 6P
RSENS 7P
Interlock switch
UPDOWN
12P
OKIPAGE 8c is a tandem color electrophotographic page printer, using technologies of 4992-LED
array, OPC, dry single-component non-magnetic developing, roller transfer, heat-compression
fixing and so on. Its printing method is a Black Writing method which applies light beams to printout
areas.
Figure 2.1 shows the functional block diagram of OKIPAGE 8c.
Figure 2.1
2 - 1
2.1 Main Control Board (PCR PCB)
The control board consists of a CPU (NR4700) block, a memory control LSI block, an interface
control LSI block, a DRAM block, an EEPROM block, a mask ROM block, and an interface block.
Figure 2.2 shows the functional block diagram of the main control board (PCR PCB).
MPU Memory controller ROM, Flash Max 32M
SysAD
SysCmd
Control
NMI
INTO
NR4700
LMQ-100
ExtReg
INT1
INT2
Reset
ColdReset
VCCOK
ModeIn
ModeClock
MasterClock
(Not installed)
External Agent
SysAD
SysCmd
Control
INT
REQ
ACK
AUX
CLK
RST
OSC
Reset circuit
DIP SW
64
9
5
1
1
1
1
64
9
5
1
1
1
1
1
1
1
1
2
1
1
1
2
SysAD
SysCmd
Control
uPD94694
NMI
S1-001-F6
INT
CLK
RST
Interface controller
SysAD
SysCmd
Control
ExtReq
INT
ColdReset
VCCOK
ModeIn
ModeClk
uPU66044
GN-013-LMU
BusReq
BusAck
AUX
Reset
CLK
RSTIN
M
A
D
Control
A
D
Control
WDATA
FSYNC
Control
PU I/F
OP I/F
EEPD
EEPCLK
EEPCS0
EEPCS1
PD
PCO
PCI
D
A
C
22
64
11
11
64
25
8
4
4
9
4
1
1
1
1
8
7
4
16
18
12
10
(TE6135 (6137), 16550, 53C80)
D-RAM Max 80M
Engine
WDATA
ESYNC
Control
Operator
panel
EE-PROM #1
DI
CLK DO
CS
EE-PROM #2
DI
CLK DO
CS
74ACT1284 Bi-Centro
74ALS244
OKI HSP
Host I/F(Not installed)
PS -SIMM
Figure 2.2
2 - 2
(1) CPU
The CPU is a 64-bit RISC architecture processor (fabricated by NKK). It inputs a frequency
of 50MHz and runs at 100MHz. It transfers data to and from memory at 50MHz.
(2) Mask ROM
The mask ROM block consists of four 16Mbit (1M x 16bits) chips and total size is 8M bytes.
The chips are mounted on the PCR-PCB by means of IC sockets and stores programs and
character fonts.
(3) DRAM
The DRAM block consists of eight 16Mbit (1M x 16bits) chips and total size is 16M bytes. The
chips are mounted on the PCR-PCB and can be expanded up to 80M bytes by adding the 32M
byte SIMMs to the SIMM slots on the PCR-PCB.
(4) EEPROM
The EEPROM block consists of 1K-bit chips mounted on a board by means of IC sockets and
stores the following:
- Menu data
- Counter values
- Adjustment values
(5) Flash ROM
The Flash ROM block consists of four 4M bit (256K x 16bits) chips and total size is 2M bytes.
The chips are mounted on the PCR-PCB and used for storing fonts, macro and demo pages.
(6) Memory control LSI
This block mainly has memory control, CPU control, compression and decompression, and
video interface functions.
(7) Interface control LSI
This block mainly has PU interface control, operator panel interface control, EEPROM
control, parallel interface control, and HSP control functions.
(8) Host interface
This printer has the following interfaces to the host.
• Centronics bidirectional parallel interface
• OKI HSP interface (Option)
The single effective interface or the automatic interface select mode can be selected using
the menu. If the busy state of the printer continues for a long time period, the buffer near-full
control releases the busy status at constant intervals even if the host side is busy so not to
cause the interface time-out at the host side.
(a) Centronics bidirectional parallel interface
This is an interface conforming to IEEE-1284 and provides either of unidirectional and
bidirectional communications according to each of the following communication modes.
• Compatibility mode
Unidirectional communications from the host to the printer.
• Nibble mode
This mode transmits 4-bit wide data from the printer to the host. In this mode, each
1-byte data is transferred in the form of two nibbles using ERROR, BUSY, FAULT,
and SELECT signal leads. This mode can provide the bidirectional operation in
combination with the compatibility mode.
2 - 3
• ECP mode
This mode provides the asynchronous bidirectional interface and transmits and
receives 1-byte data using eight data signal leads under the semi-duplex control by
the host.
When the power is turned on, the compatibility mode is automatically selected. The
change to another mode from the compatibility mode is made through negotiation.
(When the BI DIRECTION is set to ENABLE in the menu, this change can be performed.)
(For the electrical/physical characteristics of this interface, see APPENDIX B)
(b) OKI HSP interface (Option)
This interface (slot) is an OKI unique universal interface that provides the platform to
connect various of boards (including those supplied by third venders) such as the LAN
connection expansion board and SCSI expansion board.
Any expansion boards compatible with this interface can be mounted on the Control
board in the piggyback board from without modifying the program at the printer side. The
conceptual diagram of the OKI HSP interface is shown in Fig. 2-3.
Printer
Network, etc.
Control board
LAN
expansion board
(For the electrical/physical characteristics of the OKI HSP interface, see the OKI HSP
interface technical manual.)
(8) RAM module
• Pin layout
1363772
• Basic specificaton
- Type: 72 pins SIIM (32 bits buss width)
- Access time: 60ns, 70ns, 80ns
- Capacity: 4, 8, 16, 32 or 64MB
- Parity: None
OKI HSP
interface
Figure 2.3
2 - 4
2.2 Engine Control Board (PX4 PCB)
NM93C66N-NW
CPU BUS
VIDEO I/F
RESET
EEPROM
VIDEO MEM
HM658512
OSC 28MHz
(Heater temperatures and print densities)
ANALOG INPUT
CPU
MSM65524
(containing AD converter)
INT
LSI
MB87D
113PFV
ROM
27512
Y HEAD I/F (3.3V)
M HEAD I/F (3.3V)
C HEAD I/F (3.3V)
B HEAD I/F (3.3V)
MT DRIVER
MTD2009F
MT DRIVER
MTD2009F
MT DRIVER
MTD2009F
PULSE MOTOR x 8
HIGH-VOLTAGE POWER SUPPLY
SERIAL INTERFACE (2 channels)
GENERAL INPUT PORT
GENERAL OUTPUT PORT
Figure 2.4
The engine control block (PU) is controlled by the engine control board (PX4 PCB) which consists
of a CPU (MSM65524), general purpose LSI chips, EPROM, EEPROM, pulse motor drivers, and
video memory. (See Figure 2.4.)
(1) CPU
This is an 8-bit CPU (OKI MSM65524) containing an AD converter and controls the whole
system.
(2) General-purpose LSI
This LSI (MB87D113PFV) is provided in the printer engine control block and has controllerengine video interface, LED interface, motor control, sensor input, video memory control,
main scanning color correction, skew correction, high-voltage power control, and OST-EX2
functions.
2 - 5
(3) EPROM
This EPROM (27C512-150) has a storage capacity of 512K bits and stores programs for the
PU block.
(4) EEPROM
This EEPROM (NM93C66N-NW) having a storage capacity of 4K bits is mounted on the
board by means of IC socket and stores adjustment values etc.
(5) Pulse motor drivers
These drivers (MTD2005F) drive eight pulse motors for moving up and down the EP and
transferring medium.
(6) Video memory
This SRAM receives print data through video interface and stores it.
2.3 Power/Board
The power board consists of an AC filter circuit, a low voltage power supply circuit, a high voltage
power supply circuit, and heater drive circuit, and photosensors.
(1) Low voltage power supply circuit
This circuit generates the following voltages.
Output voltage Use
+3.3 V CU Unit CPU, LED HEAD
+5 V Logic circuit supply voltage
+32 V Motor and fan drive voltage and source voltage for high-voltage supply, dischange lamp
+12 V HSP, OP Amp, high voltage power supply
–12 V HSP
(2) High voltage power supply circuit
This circuit generates the following voltages necessary for electro-photographic processing
from +32 V according to the control sequence from the control board. When cover open state
is detected, +32 V supply is automatically interrupted to stop the supply of all the high-voltage
outputs.
Output Voltage Use Remarks
CH -1.35 KV ± 50V Voltage applied to charging roller
DB Normal paper Voltage applied to developing roller
Y. M. C. K : -250V/+300V, -230V/+300V(First paper. Y only)
Transparency
Y. M. C. : -200V/+300V, K. : -240V/+300V
SB Normal paper Voltage applied to toner supply roller
Y. M. C. : -350V/+450V, K. : -450V/+450V
Transparency
Y. M. C. : -300V/+450V, K. : -400V/+450V
TR 0 to 4 KV Voltage applied to transfer roller Variable
FIX 0 to 2.5 KV Voltage applied to transfer roller Variable
2 - 6
2.4 Mechanical Processes
Paper
ejection
roller
Paper
ejection
(Face down)
Power
supply
Charging
roller
Cleaning
blade
Power
supply
Paper
path
selection
Heat roller
Ejection
roller
Fixing
Backup roller
Control signal
LED head
Developing
roller
Power
supply
Toner
cartridge
Transfer
roller
Paper
resist
Resist
roller 1
Paper
feed
Hopping
roller
Power
supply
Resist
roller 2
Paper ejection Fixing Cleaning Transferring
Paper pickup
Paper conveying Paper hopping
Movement of
paper
Rotation of
OPC drum
Transferring
Charging
Exposure
Developing
Cleaning
Paper ejection
sensor
Form feed sensor 1
Paper
ejection
(Face up)
Form feed sensor 2
Front
feeder
Paper
cassette
Paper
resist
Paper
pickup
(FF, 1ST, 2ND)
Write sensor
x 4
Y M C K
Figure 2.5 shows the mechanical processes of OKIPAGE 8c.
Figure 2.5
2 - 7
2.4.1 Electrophotographic processing mechanism
(1) Electrophotographic processes
Each process of the electrophotographic processing mechanism is outlined below.
1 Paper pickup
This process causes the roller to give a DC voltage to the paper to have a charge charge.
With this negative charge, the paper is electrostatically attracted to the roller.
2 Charging
This process gives a DC voltage to the CH roller so that the OPC drum may have a uniform
negative charge on its surface.
3 Exposure
This process causes the LED head to apply light beams according to image signals to the
negatively-charged surface of the OPC drum. The negative charge on the illuminated
surface of the OPC drum is reduced according to magnitudes of the light beams.
Thus, a latent image is formed on the surface of the OPC drum according to the resulting
surface potentials.
4 Developing and recovery of excessive toner
This process applies negatively-charged toner to the surface of the OPC drum. The toner
is electrostatically attracted to the latent image to form a visible image on the surface of
the OPC drum. Simultaneously, this process electrostatically transfers excessive toner
from the OPC drum to the developing roller.
5 Transferring
This process fits paper to the surface of the OPC drum, applies positive charge (opposite
to the charge of the toner) to the back side of the paper from the transfer roller. The toner
image is transferred to the paper.
6 Cleaning
Cleaning blade scrapes off the remaining toner from the OPC drum which has been used
to transfer.
7 Fixing
This process fixes the toner image on the paper by pressing and fusing the image.
2 - 8
(2) Paper pickup
Pickup roller
Paper (medium)
Conveying belt
A
Conveying belt
Driven roller
B
Power
supply
A DC voltage (0V to 2KV) is applied to the driven roller A to negatively charge the lower
surface of the paper. The negatively-charged paper is electrostatically attracted to the pickup
roller. With this, the paper is in close-contact with the conveying Belt and conveyed steadily.
2 - 9
(3) Charging
This process applies a DC voltage to the charging roller in contact with the surface of the OPC
drum.
Power
supply
unit
OPC drum
Charging roller
(4) Exposure
The light beams from the LED head are applied to the surface of the OPC drum which is
charged negatively. The negative charge on the illuminated surface of the OPC drum is
reduced according to magnitudes of the light beams and a latent image is formed on the
surface of the OPC drum according to the resulting surface potentials.
Power
supply
unit
Charging roller
OPC drum
LED head
Paper
LED head
OPC drum
2 - 10
(5) Developing
This process applies toner to the latent image on the surface of the drum to convey it into a
toner image. Developing is carried out on the surface of the OPC drum at which the OPC drum
is in contact with the developing roller.
1 The sponge roller transfers toner to the developing roller. The toner is charged
negatively.
Developing toner blade
Charging roller
Sponge roller
Developing roller
OPC drum
2 The toner blade scrapes away excessive toner on the developing roller to form a thin
film of toner on the surface of the developing roller.
3 The toner is attracted to the latent image on the surface of the OPC drum at which
the OPC drum is in contact with the developing roller. The latent image on the
surface of the OPC drum is made visible with the toner.
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(6) Transferring
The transfer roller made of conductive sponge presses the paper
against the surface of the OPC drum so that the paper may be close contact with the surface
of the OPC drum.
This process fits the paper to the surface of the OPC drum by the transfer roller and applies
positive charge (opposite to the charge of the toner) from under the paper.
When a positive high voltage is applied to the transfer roller from the power supply, the
positive charge induced on the transfer roller jumps to the upper surface of the paper at which
the transfer roller touches the paper and attracts the negatively-charged toner from the
surface of the OPC drum onto the surface of the paper.
OPC drum
Paper
Transfer roller
Power
supply unit
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(7) Fixing The toner image just transferred to the paper is fused and fixed to the paper while
the paper is passing through the gap between the heat roller and the backup roller.
The teflon-coated surface of the heat roller is heated up by the 800-watt heater (or a
halogen lamp) provided in the heat roller. The temperature of the heat roller surface is
controlled by a thermistor in contact with the surface of the heat roller. A thermostat is
provided for safety. When the heat roller temperature goes higher than the preset
temperature, the thermostat opens and shut off power to the heater in the heat roller.
The backup roller is evenly pushed against the heat roller by two end springs.
Heater
Paper
Heat roller
Thermistor
Backup roller
(8) Cleaning
After the toner image is transferred to the paper, the cleaning roller electrostatically attracts
toner which is left untransferred on the OPC drum to the cleaning roller. The toner is returned
to the OPC drum for re-use.
OPC drum
Cleaning blade
Transfer roller
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2.4.2 Paper running process
face down stacker
oil roller
fuser
low-voltage power supply
AC switch
density sensor
transfer roller
x
4 light rejector
x
4
transfer belt unit
ID unit up / down actuater
belt cleaning
high voltage power supply
adsorption roller
pinch roller up / down
transfer belt
1st tray
2nd tray
front feeder
KCMY
I/D unit
LED Head
pinch roller 2
pinch roller 1
regist
roller 2
regist
roller 1
hopping roller
backup roller
Eject roller
oil cleaning roller
heat roller
Figure 2.6 shows how paper moves in the OKIPAGE 8c.
Figure 2.6 Paper Route
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(1) Paper hopping and transfer and up/down movement of pinch roller 2
Paper is hopped and delivered by the mechanism shown below. This mechanism is driven
by a single pulse motor.
Resist roller 2
One-way gear C
Resist roller 1
Idle gear C
One-way gear B
Idle gear A
a
b
Idle gear B
First hopping roller
Pulse motor
One-way gear A
The pulse motor turns in the arrow direction (a) and drives the hopping roller in the direction of
“b.” The hopping roller drives the resist roller.
Each of the one-way clutch gears A, B, and C has a one-way clutch to prevent the rollers from
rotating reversely.
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(a) Hopping
1 The pulse motor turns in the arrow direction of “a” (counterclockwise) and drives the
hopping roller to move the paper until the Entrance sensor turns on. Although the oneway gears B and C are also driven, the resist roller 2 does not turn because the
reverse rotations of the one-way clutch gears are not transmitted to the resist roller.
2 After the Entrance sensor turns on, the hopping roller keeps on feeding the paper until
it hit the resist roller 1. (This operation corrects any paper skew.)
One-way gear C
Resist roller 1
Resist roller 2
One-way gear B
Entrance sensor
Paper
a
First hopping roller
(b) Conveying
1 After paper hopping is completed, the pulse motor turns right (in the direction of “b”)
to drive the resist rollers 1 and 2. The resist rollers feed the paper until the Form
sensor turns on.
Although the one-way gear A is also driven, the hopping roller does not turn because
of the one-way clutch.
2 The paper is further fed in synchronism with the print data.
Form sensor
Resist roller 1
Paper
One-way gear A
Resist roller 2
b
First hopping roller
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(2) The hopping operation of the front feeder and the up/down operation of the pinch roller 2 are
performed by a single pulse motor, as shown below.
Cam
b
a
Idle gear A
One-way clutch gear B
Sensor position
From front
Hopping roller
One-way clutch gear A Idle gear B
Entrance sensor
Up/down
Pinch roller
Form sensor
Resist roller 2
When the pulse motor of the front feeder turns right (in the direction of “A”), the front hopping
roller turns left (in the direction of “b”) to drive the cam. This cam moves up and down
the pinch roller 2. The one-way clutch gears are made to turn only in a preset direction by
means of the one-way clutches.
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