OKI OKIPAGE 8c Plus, OKICOLOR 8 Service manual

OKIPAGE 8c Plus
/ OKICOLOR 8
Color LED Page Printer

MAINTENANCE
MANUAL

ODA/OEL/INT

1999.8.12 Rev.1

41057601TH Rev.1 1 / 199

Rev.No. Date Corrected items Person in

No. Page Description of change change

1 1999.8.12 ISSUE E4 Yamazaki

41057601TH Rev.1 2 /

PREFACE

This maintenance manual provides procedures and techniques for the troubleshooting, maintenance, and
repair of OKICOLOR 8 / OKIPAGE 8c Plus.

This manual is written for maintenance personnel, but it should always be accompanied with the
OKICOLOR 8 / OKIPAGE 8c Plus User’s Manual for procedures for handling and operating OKICOLOR
8 / OKIPAGE 8c Plus. For repairing each component of OKICOLOR 8 / OKIPAGE 8c Plus, see the
Troubleshooting manual.

[Notices]
The contents of this manual are 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 some 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 OKICOLOR 8 / OKIPAGE 8c Plus in any manner.

[Warning]
Many parts of OKICOLOR 8 / OKIPAGE 8c Plus are very sensitive and can be easily damaged by improper
servicing. We strongly suggest that OKICOLOR 8 / OKIPAGE 8c Plus be serviced by OKI’s authorized
technical service engineers.

41057601TH Rev.1 3 /

CONTENTS

1. SPECIFICATIONS ............................................................................................ 7

1.1 Basic System Configuration............................................................................................. 7

1.2 Printer Specifications .......................................................................................................8

1.3 Option Specifications ....................................................................................................... 9

1.4 Basic Specifications....................................................................................................... 10

2. OPERATION................................................................................................... 12

2.1 Main Control Board (PCE PCB)..................................................................................... 13

2.2 Engine Control Board (PX4 PCB) .................................................................................. 16

2.3 Power/Units.................................................................................................................... 17

2.4 Mechanical Processes................................................................................................... 18

2.4.1 Electrophotographic processing mechanism .................................................... 19

2.4.2 Paper running process ..................................................................................... 25

2.5 Sensors.......................................................................................................................... 34

2.5.1 Paper related sensors ...................................................................................... 34

2.5.2 Other sensors ................................................................................................... 35

2.6 Correction of Color Deviation......................................................................................... 36

2.7 Transfer Control according to Environmental Changes

(Room Temperatures and Relative Humidities)............................................................. 36

2.8 Form Jam Detection....................................................................................................... 37

2.9 Cover Opening............................................................................................................... 37

2.10 Toner Low Detection...................................................................................................... 38

2.11 Page Size Detection ...................................................................................................... 39

2.12 Power-on Processing..................................................................................................... 40

2.12.1 Self-diagnostic test ........................................................................................... 40

3. PARTS REPLACEMENT................................................................................41

3.1 Precautions for Parts Replacement ............................................................................... 41

3.2 Parts Layout................................................................................................................... 43

3.3 How to Change Parts..................................................................................................... 47

3.3.1 Cover Assy Rear .............................................................................................. 48

3.3.2 Motor-Fan (80-25) ............................................................................................ 49

3.3.3 Paper Eject Assy .............................................................................................. 50

3.3.4 Cover Assy Stacker, Guide Eject FD Assy....................................................... 51

3.3.5 Frame Assy Upper............................................................................................ 52

3.3.6 Plate Support Assy ........................................................................................... 53

3.3.7 Limiter 2way (L), (R) / Plate Guide (L) , (R) ...................................................... 54

3.3.8 Cover ............................................................................................................... 55

3.3.9 PCB Assy : PCE ............................................................................................... 56

3.3.10 Motor Fan (CU)................................................................................................. 57

3.3.11 PXF PCB/PX4 PCB .......................................................................................... 58

3.3.12 Gear Heat Assy ................................................................................................ 59

3.3.13 Main Motor (A), (B) Assy .................................................................................. 60

3.3.14 Gear One-way (Z30)......................................................................................... 61

3.3.15 Motor Assy BT .................................................................................................. 62

3.3.16 Power Supply Unit, Holder Inlet, Sheet Insulation............................................ 63

3.3.17 Sensor Assy Box Toner .................................................................................... 64

3.3.18 Square-shaped Connector ............................................................................... 65

41057601TH Rev.1 4 /

3.3.19 Hopping Motor .................................................................................................. 66

3.3.20 Gear One-way .................................................................................................. 67

3.3.21 Feeder Unit Front ............................................................................................. 68

3.3.22 Manual Feed Hopper Assy ............................................................................... 69

3.3.23 Guide Paper Input Assy.................................................................................... 70

3.3.24 Two Lever Input Sensors, Lever 2nd Feed Sensor .......................................... 71

3.3.25 Roller Registration, Roller Assy Hopping ......................................................... 72

3.3.26 Roller Hopping.................................................................................................. 73

3.3.27 PXU PCB/PXM PCB, Lever Resist Sensor ...................................................... 74

3.3.28 Paper End Lever............................................................................................... 75

3.3.29 PCO PCB (Operator Panel).............................................................................. 76

3.3.30 Holder Gear Toner Assy................................................................................... 77

3.3.31 Plate Latch Lever (FD), Spring Latch Lever (FD) ............................................. 78

3.3.32 Belt Cassette Assy ........................................................................................... 79

3.3.33 High Voltage Power Supply Unit, Bracket HV (BT) Assy ................................. 80

3.3.34 Eraser Bracket Assy, Eraser Bracket (KCM) Assy ........................................... 81

3.3.35 Shaft Link.......................................................................................................... 82

3.3.36 Contact (BL-R) Assy, Contact (CL-R) Assy ...................................................... 83

3.3.37 Contact (BL-L) Assy, Contact (CL-L) Assy ....................................................... 84

3.3.38 Contact SB Assy............................................................................................... 85

3.3.39 PXC PCB .......................................................................................................... 86

3.3.40 Heat Unit Assy.................................................................................................. 87

3.3.41 Oil Roller Assy .................................................................................................. 88

3.3.42 Lever Lock Heat (L)/(R), Guide Side Heat, Spring Lock................................... 89

3.3.43 PXL PCB .......................................................................................................... 90

3.3.44 Heat Unit Guide Assy ....................................................................................... 91

3.3.45 Holder LED Assy, LED Head............................................................................ 92

4. ADJUSTMENTS ............................................................................................. 93

4.1 Maintenance Modes and Their Functions...................................................................... 93

4.1.1 User maintenance mode .................................................................................. 93

4.1.2 System maintenance mode .............................................................................. 95

4.1.3 Engine maintenance mode ............................................................................... 97

4.2 Adjustments after Parts Replacement ......................................................................... 100

4.2.1 Confirm the LED head driving time................................................................. 100

4.2.2 Color deviation correction............................................................................... 102

5. PERIODIC MAINTENANCE ......................................................................... 105

5.1 Periodically Replaced Parts ......................................................................................... 105

5.2 Cleaning....................................................................................................................... 105

5.3 Cleaning the LED Lens Array ...................................................................................... 105

5.4 Cleaning the Pickup Roller........................................................................................... 105

6. TROUBLESHOOTING PROCEDURES ....................................................... 106

6.1 Troubleshooting Tips ................................................................................................... 106

6.2 Points to Check before Correcting Image Problems.................................................... 106

6.3 Tips for Correcting Image Problems ............................................................................ 106

6.4 Preparation for Troubleshooting .................................................................................. 107

6.5 Troubleshooting Flow................................................................................................... 107

6.5.1 LCD status message/trouble list..................................................................... 107

6.5.2 LCD message troubleshooting ....................................................................... 116

6.5.3 Image troubleshooting .................................................................................... 129

41057601TH Rev.1 5 /

7. WIRING DIAGRAM...................................................................................... 146

7.1 Resistance Check ........................................................................................................ 146

7.2 Program/Font ROM Location ....................................................................................... 150

8. Parts List...................................................................................................... 154

Appendix A CENTRONICS PARALLEL INTERFACE.................................... 175

Appendix B HIGH CAPACITY SECOND PAPER FEEDER ........................... 179

1. OUTLINE ......................................................................................................179

1.1 Functions ..................................................................................................................... 179

1.2 External View and Component Names........................................................................ 179

2. MECHANISM DESCRIPTION ...................................................................... 180

2.1 General Mechanicsm................................................................................................... 180

2.2 Hopper Mechanism...................................................................................................... 181

3. PARTS REPLACEMENT..............................................................................182

3.1 Precautions Concerning Parts Replacement............................................................... 182

3.2 Parts Layout................................................................................................................. 184

3.3 Parts Replacement Methods........................................................................................ 185

3.3.1 Idle rollers ....................................................................................................... 186

3.3.2 AOLT-PCB...................................................................................................... 187

3.3.3 Hopping motor ................................................................................................ 188

3.3.4 Feed roller ...................................................................................................... 189

3.3.5 Hopping roller ................................................................................................. 190

3.3.6 Side frame (L) assy ........................................................................................ 191

3.3.7 Side frame (R) assy........................................................................................ 192

4. TROUBLESHOOTING.................................................................................. 193

4.1 Precautions Prior to the Troubleshooting..................................................................... 193

4.2 Preparations for the Troubleshooting........................................................................... 193

4.3 Troubleshooting Method .............................................................................................. 194

4.3.1 LCD Status Message List ............................................................................... 194

4.3.2 Troubleshooting Flow ..................................................................................... 195

5. CONNECTION DIAGRAM............................................................................ 196

5.1 Interconnection Diagram.............................................................................................. 196

5.2 PCB Layout.................................................................................................................. 197

6. PARTS LIST ................................................................................................. 198

41057601TH Rev.1 6 /

M

M M

M M

M M

M

LED head

Discharging indicators

Centronics

interface

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

x4

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 OKICOLOR 8 / OKIPAGE 8c Plus is illustrated in Figure 1.1.

Figure 1.1

41057601TH Rev.1 7/

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

I/F Cover Assy

Rear Cover

Side Cover (L) Assy

Base Unit

Figure 1.2

Operator Panel Assy

41057601TH Rev.1 8/

1.3 Option Specifications

Options available for OKICOLOR 8 / OKIPAGE 8c Plus 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.

41057601TH Rev.1 9/

1.4 Basic Specifications

(1) Dimensions

Width: 18.8" (478mm) Length: 24.5" (622mm) Height: 15.6" (396mm)

(2) Weight

Approx. 48kg (106lbs)

(3) Form

Type: Ordinary paper (Hammermill 24lbs) and OHP (Only CG3710)

Recommended paper (for color printing)
Color laser paper (20lb to 24lbs)
Note: The printout color tones are dependent upon the whiteness of the print

paper
Sizes: Letter, Legal (13"or 14"), Executive, A4, A5, B5, and A6 (1st tray and front feeder)
Reams: 1st tray 20lbs to 28lbs

2nd tray 20lbs to 28lbs

Front feeder 20lbs to 44lbs

(5) Printing speed

8 pages per minute (5 pages per minute: OHP/ 34lbs ~44lbs, 123g/m2~166g/m2)

(6) Resolution

600 dots per inch x 600 dots per inch

(7) Input voltage

120VAC +5.5%, -15%
230VAC ±10%

(8) Power consumption

Peak W
Typical operation W
Idle W
Power-save mode W

(9) Frequency

50Hz or 60Hz +2%, -2%

(10) Noises

Operating: 54dB (without 2nd tray), 55dB (with 2nd tray)
Standby: 45dB
Power-saving: 43dB

(11) Expendibles and service life

Toner cartridge: Approx. 1800 pages (5% duty) (each of Y, M, C, and K)

(Approx. 1000 sheets for the first)
Image drum: Up to 12,000 pages (5% duty, continuous) (each of Y, M, C, and K)
Waste Toner Box: Up to 25,000 Sheets

(under typical printout conditions: Single images of 5% density,

equivalent to printout using 14 toner cartridges)
Oil Roller Unit: Up to 10,000 sheets (Life defined in the number of actually printed

paper sheets)

(12) Periodically-replaced parts

Heat Unit Assy: 60,000 pages
Belt Cassette Assy: 50,000 pages

41057601TH Rev.1 10/

(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 122

-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 50

-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
without drum and toner and
Belt Cassette Assy
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

41057601TH Rev.1 11/

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

PCE

Operator

panel

PCO

board

CM

6P

PU 40P

72PX2

PS SIMM

72PX4

D-RAM SIMM

64P

OKI HSP

36P

Parallel

CUIF 40P

POWER 30P

THE.RM 6P

RSENS 7P

Interlock switch

UPDOWN

12P

OKICOLOR 8 / OKIPAGE 8c Plus is a tandem color electrophotographic page printer, using 4992­LED technologies , OPC, dry single-component non-magnetic developing, roller transfer, heat­compression fixing and so on. The printing method used is a Black Writing method which applies
light beams to printout areas.

Figure 2.1 shows the functional block diagram of OKICOLOR 8 / OKIPAGE 8c Plus.

41057601TH Rev.1 12/

Figure 2.1

2.1 Main Control Board (PCE PCB)

The control board consists of a CPU (µPD30500S2-200) 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 (PCE PCB).

MPU Memory controller ROM, Flash Max 32M

SysAD

SysCmd

Control

NMI

INTO

µ

PD30500

S2-200

ExtReg

INT1

Reset

ColdReset

VCCOK

ModeIn

ModeClock

MasterClock

2nd cache controller

SysAD

SysCmd

Control

Control

64

9
5

1
1

1
1

64

9
5
1
1

1
1
1
1

SysAD
SysCmd
Control

uPD94704

NMI

S1-001-F6

INT

CLK
RST

Interface controller
SysAD
SysCmd
Control
ExtReq
INT

ColdReset
VCCOK
ModeIn
ModeClk

uPU66044
GN-014-LMU

A
D

Control

A
D

Control

WDATA
FSYNC

Control

PU I/F
OP I/F

EEPD
EEPCLK
EEPCS0

PD

PCO

PCI

22
64

11

11
64
25

8
4
4

9
4

1
1
1

8
5

4

D-RAM Max 144M

74LVC161284 Bi-Centro

WDATA
ESYNC
Control

Operator
panel

DI
CLK DO
CS

Engine

EE-PROM

2nd cache

Control

Reset circuit

SysAD

OSC

DIP SW

16

D

18

A

12

1

Reset

1

CLK

1

RSTIN

2

M

C

10
(TE6135 (6137), 16550, 53C80)

OKI HSP

Host I/F(Not installed)

Figure 2.2

41057601TH Rev.1 13/

(1) CPU

The CPU is a 64-bit RISC architecture processor (provided by NEC). It inputs a frequency
of 50MHz and runs at 200MHz. It transfers data to and from memory at 50MHz.

(2) OTP ROM

The otp ROM block consists of four 16Mbit (1M x 16bits) chips and its total size is 8M bytes.
The chips are mounted on the PCE-PCB by means of IC sockets and store programs and
character fonts.

(3) DRAM

The DRAM block consists of eight 16Mbit (1M x 16bits) chips and its total size is 16M bytes.
The chips are mounted on the PCE-PCB and can be expanded up to 144M bytes by adding
the 32M byte SIMMs to the SIMM slots on the PCE-PCB.

(4) EEPROM

The EEPROM block consists of 16K-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 its total size is 2M
bytes. The chips are mounted on the PCE-PCB and are used for storing fonts, macro and
demo pages.

(6) Memory control LSI

This block mainly consists of memory control, CPU control, compression and decompres­sion, and video interface functions.

(7) Interface control LSI

This block mainly consists of 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

• 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 as not
to cause interface time-out at the host side.

(a) Centronics bidirectional parallel interface

This is an interface conforming to IEEE-1284 and provides either 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 transfers 4-bit wide data from the printer to the host. In this mode, each
bit of 1-byte data is transmits in the form of two nibbles using ERROR, BUSY, FAULT,
and SELECT signal leads. This mode can provide bidirectional operation in
combination with the compatibility mode.

41057601TH Rev.1 14/

• ECP mode
This mode provides the asynchronous bidirectional interface and transmits and
receives 1-byte data using eight data signal leads under 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) 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 HSP interface is shown in Fig. 2-3.

Printer

Network, etc.

Control board

LAN

expansion board

HSP

interface

Figure 2.3

(For the electrical/physical characteristics of the HSP interface, see the HSP interface
technical manual.)

(9) 2nd Cache and 2nd Cache Controller

This printer has 2nd Cache unit which type is Write Through Cache and size is 512 KByte.
Thereare any difference between the instruction and data.
All of the CPU read/ write accesses are cached to same 2nd Cache memory.

(10) RAM module

• Pin layout

1363772

• Basic specificaton

- Type: 72 pins SIMM (32 bits buss width)

- Access time: 60ns, 70ns, 80ns

- Capacity: 4, 8, 16 or 32MB

- Parity: None

41057601TH Rev.1 15/

2.2 Engine Control Board (PX4 PCB)

NM93C66N-NW

CPU BUS

VIDEO I/F

(Heater temperatures and envirnment humidity and temperature)

EEPROM

VIDEO MEM

HM658512

OSC 28MHz

RESET

ANALOG INPUT

CPU

MSM65524

(containing AD converter)

INT

LSI

MB87D

113PFV

MT DRIVER

MTD2005F

MT DRIVER

MTD2005F

MT DRIVER

MTD2005F

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)

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 the 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.

41057601TH Rev.1 16/

(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/Units

The power supply unit comprises of the low voltage power supply unit which consists of an AC filter
circuit, low voltage power supply circuit and heater driver circuit, and the high voltage power supply
unit.

(1) Low voltage power supply unit

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, discharge lamp
+12 V HSP, OP Amp, high voltage power supply
–12 V HSP

(2) High voltage power supply unit

This circuit generates the following voltages necessary for electro-photographic processing
from +32 V in accordance with 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 high­voltage 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 : -250V/+300V, -232V/+300V(First paper. Y only)
K : -275V/+300V
Transparency

Y. M. C. : -200V/+300V, K. : -250V/+300V
SB Y. M. C.K : -650V/0V Voltage applied to toner supply roller
TR 0 to 4 KV Voltage applied to transfer roller Variable
FIX 0 to 2.5 KV Voltage applied to transfer roller Variable

41057601TH Rev.1 17/

2.4 Mechanical Processes

Paper

ejection

roller

Paper

ejection

(Face down)

Power

supply

Charging

roller

Cleaning

blade

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 OKICOLOR 8/ OKIPAGE 8c Plus.

41057601TH Rev.1 18/

Figure 2.5

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 negative 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.

41057601TH Rev.1 19/

(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 positive 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.

41057601TH Rev.1 20/

(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

41057601TH Rev.1 21/

(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.

41057601TH Rev.1 22/

(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

Conveying belt

Paper

Transfer roller

Power

supply unit

41057601TH Rev.1 23/

(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

Backup roller

Heat roller

Thermistor

(8) Cleaning

The toner which remains on the OPC Drum without being fused is scraped by a cleaning blade
and discarded in the waste toner tank.

OPC drum

Cleaning blade

Transfer roller

41057601TH Rev.1 24/

2.4.2 Paper running process

face down stacker

oil roller

fuser

low-voltage power supply

AC switch

transfer roller

x

4 light rejector

x

4

transfer belt unit

ID unit up / down actuater

belt cleaning

high voltage power supply

pick up 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 OKICOLOR 8/ OKIPAGE 8c Plus.

Figure 2.6 Paper Route

41057601TH Rev.1 25/

(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.

41057601TH Rev.1 26/

(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

Resist roller 2

b

Paper

First hopping roller

One-way gear A

41057601TH Rev.1 27/

(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.

41057601TH Rev.1 28/

(a) First and second hopping rollers

1 When the front edge of the paper passes by the pickup roller, the pulse motor of the

front feeder turns left (in the direction of “b” to drive the cam. The cam moves up the
pinch roller 2. Although the one-way clutch gear A is also rotating, the hopping roller
of the front feeder does not rotate by means of the one-way clutch.

2 When the rear edge of the paper passes by the Entrance sensor 2, the pulse motor

of the front feeder turns left (in the direction of “b”) to drive the cam. The cam moves
down the pinch roller 2 until it is sensed by the sensor. Although the one-way clutch
gear A is also rotating, the hopping roller of the front feeder does not rotate by means
of the one-way clutch.

Cam

b

One-way clutch gear B

Idle gear A

Hopping roller

One-way clutch gear A

Idle gear B

b

b

Paper from the tray

b

Entrance sensor 2

b

Up

Cam

Sensor

Pickup roller

Form sensor

Pinch roller 2

Resist roller 2

41057601TH Rev.1 29/

(b) Front feeder hopping

1 The pulse motor of the front feeder turns right (in the direction of “a” to drive the

Idle gear A

Hopping roller

One-way clutch gear A

Paper from front feeder

hopping roller. The paper is fed until the Entrance sensor 2 turns on. Although the
one-way clutch gear B is also rotating, the pinch roller 2 does not drive the up/down
cam by means of the one-way clutch.
After turning on the Entrance sensor, the paper is further fed until it hits the resist roller

2. (This operation corrects any paper skew.)

One-way clutch gear B

a

b

Cam

Sensor

Pickup roller 2

Form sensor

Idle gear B

Entrance sensor 2

Resist roller 2

(c) 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.

2 Although the one-way gear A is also driven, the first hopping roller does not turn

because of the one-way clutch.

Paper

b

Form sensor

Resist roller 2

One-way gear A First hopping roller

41057601TH Rev.1 30/