Brother HL-1260 User Manual

R

LASER PRINTER

SERVICE MANUAL

MODEL:HL-1260

No part this publication may be reproduced in any form or by any means without permission in writing from the publisher.

Trademarks:

•BR-Script, and DX-1200 are registered trademarks of Brother Industries, Ltd.

•Centronics is a registered trademark of Genicom Corporation.

•PostScrip is a registered trademark of Adobe Systems Incorporated.

•IBM Proprinter XL is a registered trademark of International Business Machines Corporation.

•EPSON FX-850 is a registered trademark of Seiko Epson Corporation.

•HP-GL and HP Laser Jet 4 are registered trademarks of Hewlett Packard Company.

PREFACE

This service manual contains basic information required for after-sales service of the laser printer (hereinafter referred to as ”this machine” or ” the printer”). This information is vital to the service technician in maintaining the high printing quality and performance of the printer.

This manual consists of the following chapters:

Chapter I	:	General
		Features, specifications, etc.
Chapter II	:	Theory of Operation
		Basic operation of the mechanical system and the electrical system, and their timing.
Chapter III	:	Electrical System
		Theory of the electronics circuit
Chapter IV	:	Mechanical System
		Requirements for a suitable location, disassembling and reassembling procedure of
		mechanical system.
Chapter V	:	Maintenance and Servicing
		Parts replacement schedule, list of tools, lubricants and cleaners.
Chapter VI	:	Troubleshooting
		Reference values and adjustment, troubleshooting for image defects, troubleshooting
		for malfunctions, etc.
Appendices :		Engine Block Diagram, PCB Circuitry Diagrams, etc.

Information in this manual is subject to change due to improvement or re-design of the product. All relevant information in such cases will be supplied in service information bulletins (Technical Information).

A thorough understanding of this printer, based on information in this service manual and service information bulletins, is required for maintaining its quality performance and for fostering the practical ability to find the cause of troubles.

			CONTENTS
CHAPTER I			GENERAL
1.	FEATURES ........................................................................................................................			I-1
2.	SPECIFICATIONS ..............................................................................................................			I-1
3.	SAFETY INFORMATION....................................................................................................			I-6
	3.1	Laser Safety (110 - 120V Model only) ......................................................................		I-6
	3.2	CDRH Regulations (110 - 120V Model only) ............................................................		I-7
	3.3	Additional Information ..............................................................................................		I-7
4.	PARTS OF THE PRINTER .................................................................................................			I-8
	4.1	External Views .........................................................................................................		I-8
	4.2	Cross Sectional View ...............................................................................................		I-9
5.	STORAGE AND HANDLING OF EP-ED CARTRIDGES ..................................................			I-10
	5.1	Storage of Sealed EP-ED Cartridges .....................................................................		I-10
	5.2	Storage of Unsealed EP-ED Cartridges .................................................................		I-10
CHAPTER II			THEORY OF OPERATION
1.	BASIC OPERATIONS .......................................................................................................			II-1
	1.1	Mechanical Configuration ........................................................................................		II-1
	1.2	Main Drive ...............................................................................................................		II-2
	1.3	Basic Sequence of Operations ................................................................................		II-3
2.	LASER/SCANNER SYSTEM ............................................................................................			II-4
3.	IMAGE FORMATION SYSTEM .........................................................................................			II-5
	3.1	Outline .....................................................................................................................		II-5
	3.2	Printing Process ......................................................................................................		II-5
		3.2.1 Electrostatic latent image formation stage ................................................		II-6
		3.2.2	Developing stage ......................................................................................	II-8
		3.2.3	Transfer stage ...........................................................................................	II-9
		3.2.4	Fixing stage ............................................................................................	II-10
		3.2.5	Drum cleaning stage ...............................................................................	II-10
	3.3	Operation ..............................................................................................................		II-11
4.	PAPER PICK-UP/FEED SYSTEM ...................................................................................			II-12
	4.1	Outline ...................................................................................................................		II-12
	4.2	Cassette Feed .......................................................................................................		II-13
	4.3	MP Tray Feed ........................................................................................................		II-14
	4.4	Paper Jam Detection .............................................................................................		II-15

i

CHAPTER III ELECTRICAL SYSTEM
1.	MAIN PCB ........................................................................................................................		III-1
	1.1	Outline ....................................................................................................................	III-1
	1.2	Video Controller Circuit ..........................................................................................	III-2
	1.3	Engine Controller Circuit ........................................................................................	III-7
2.	PAPER FEED DRIVE CIRCUIT .......................................................................................		III-9
3.	DISPLAY CIRCUIT .........................................................................................................		III-11
	3.1	Outline ..................................................................................................................	III-11
	3.2	Operation .............................................................................................................	III-11
4.	LOW-VOLTAGE POWER SUPPLY ASSY .......................................................................		III-12
	4.1	Outline ..................................................................................................................	III-12
	4.2	Protection Functions ............................................................................................	III-12
5.	HIGH-VOLTAGE POWER SUPPLY ASSY ......................................................................		III-14
	5.1	Outline ..................................................................................................................	III-14
	5.2	Operation of the Components of the High-Voltage Power Supply Assy ...............	III-14

CHAPTER IV			MECHANICAL SYSTEM
PRINTER DISASSEMBLING PROCEDURE
PRINTER BODY
1.1		Configuration ..........................................................................................................		IV-3
1.2		Toner Cartridge Lid ................................................................................................		IV-3
1.3		Side Cover L ..........................................................................................................		IV-3
1.4		Font Cover Assy .....................................................................................................		IV-4
1.5	Upper Cover Assy, Rear Cover Assy ......................................................................			IV-4
		1.5.1 Upper cover assy, rear cover assy ...........................................................		IV-4
		1.5.2 Changeover guide, jam remove cover ......................................................		IV-5
1.6		Side Cover R ..........................................................................................................		IV-5
1.7		DC Fan Motor .........................................................................................................		IV-6
1.8		Main PCB ...............................................................................................................		IV-6
1.9		Control Panel Unit ..................................................................................................		IV-8
1.10		Scanner Unit ..........................................................................................................		IV-9
1.11		Cartridge Stopper Assy ..........................................................................................		IV-9
1.12		Paper Feed Chassis Unit .....................................................................................		IV-10
1.13		Separation Pad Assy ............................................................................................		IV-11
1.14		MP PE Sub Actuator ............................................................................................		IV-12
1.15		P Feed /Size-SW PCB Assy .................................................................................		IV-12
1.16		Side-Switch Spring ...............................................................................................		IV-12
1.17		Regist Sensor Actuator ........................................................................................		IV-13
1.18		MP Paper Detection Actuator ...............................................................................		IV-13
1.19		PE Sensor Actuator MP .......................................................................................		IV-13
1.20		Tray Sensor Holder ..............................................................................................		IV-14
1.21		Roller Holder ........................................................................................................		IV-14
1.22		Paper Pick-up Roller Assy, Bearing ......................................................................		IV-15
1.23		Paper Pick-up Solenoid ........................................................................................		IV-16
1.24		Paper Feed Motor Assy ........................................................................................		IV-16
1.25		MP Tray Cover ......................................................................................................		IV-17
1.26		MP Tray Assy .......................................................................................................		IV-17
1.27		Paper Path Separation Plate, Paper Path Separation Film ..................................		IV-18
1.28		Latch	....................................................................................................................	IV-19
1.29		Fixing Unit (for both 120V and 230V, the only difference is the halogen heater) . IV-19
1.30		Transfer .........................................................................................................Unit		IV-22

ii

1.31	DC Gear Holder Assy ...........................................................................................	IV-23
1.32	PS Switch Wire, Remote Switch ..........................................................................	IV-23
1.33	High-Voltage Power Supply PCB Assy .................................................................	IV-24
1.34	Low-Voltage Power Supply PCB Assy ..................................................................	IV-24
1.35	Toner Cartridge (EP-ED Cartridge) ......................................................................	IV-25
1.36	Paper Tray ............................................................................................................	IV-25

CHAPTER V MAINTENANCE AND SERVICING

1.	PERIODICAL REPLACEMENT PARTS ............................................................................	V-1
2.	CONSUMABLE PARTS STANDARD ENDURANCE TABLE .............................................	V-1
3.	LIST OF STANDARD TOOLS ............................................................................................	V-2
4.	LIST OF LUBRICANTS AND CLEANERS ........................................................................	V-3

CHAPTER VI TROUBLESHOOTING

1.	INTRODUCTION ..............................................................................................................		VI-1
	1.1	Initial Check............................................................................................................	VI-1
	1.2	Basic Procedure .....................................................................................................	VI-2
2.	TEST PRINTING AND MECHANICAL CHECK ...............................................................		VI-2
	2.1	Test Printing ...........................................................................................................	VI-2
3.	IMAGE DEFECTS ............................................................................................................		VI-3
	3.1	Image Defect Examples .........................................................................................	VI-3
	3.2	Troubleshooting Image Defects ..............................................................................	VI-4
4.	TROUBLESHOOTING OF MALFUNCTIONS ................................................................		VI-11
5.	TROUBLESHOOTING PAPER TRANSPORT PROBLEMS ...........................................		VI-19
	5.1	Paper Jams ..........................................................................................................	VI-19
	5.2	Incomplete Paper Feed ........................................................................................	VI-22
6.	OPERATION ..................................................................................................................		VI-23
	6.1	Line Inspection Mode Procedure .........................................................................	VI-23
	6.2	DRAM Test ...........................................................................................................	VI-25
7.	STATUS MESSAGE LIST ...............................................................................................		VI-26

APPENDICES

1.	Engine Block Diagram .......................................................................................................	A-1
2.	Paper Feed/Size-SW PCB Circuitry Diagram (1/1)............................................................	A-2
3.	Main PCB Circuitry Diagram (1/8) .....................................................................................	A-3
4.	Main PCB Circuitry Diagram (2/8) .....................................................................................	A-4
5.	Main PCB Circuitry Diagram (3/8) .....................................................................................	A-5
6.	Main PCB Circuitry Diagram (4/8) .....................................................................................	A-6
7.	Main PCB Circuitry Diagram (5/8) .....................................................................................	A-7
8.	Main PCB Circuitry Diagram (6/8) .....................................................................................	A-8
9.	Main PCB Circuitry Diagram (7/8) .....................................................................................	A-9
10. Main PCB Circuitry Diagram (8/8) ...................................................................................		A-10
11. Control Panel PCB Circuitry Diagram (1/1) .....................................................................		A-11
12. Scanner LD PCB Circuitry Diagram (1/1) ........................................................................		A-12

iii

CHAPTER I GENERAL

1.FEATURES

A.This high-speed, non-impact (low-noise) printer is based on electrophotography, electronics and laser technology.

B.The printer is compact and easy to carry. The internally-storable, front-loading paper cassette enables you to save an occupation space for the machine; the printer can now be installed in a smaller place.

C.The charging roller, developing cylinder, photosensitive drum and cleaner of the printer are combined into a single assembly called an ”EP-ED cartridge”. The cartridge can be replaced by the user when necessary without a need of service call. High printing quality is maintained by a simple cleaning procedure.

D.Laser beam safety is designed into the printer. The printer is approved by the US Center for Devices and Radiological Health (CDRH).

E.Paper can be fed in two ways, by the multi-purpose paper feed tray and paper cassette.

F.Maintenance is easy with print component units which are directly detachable, and they require no adjustment after reassembly.

2.SPECIFICATIONS

(1)	Type	Desktop page printer
(2)	Printing method	Electrophotography (single-component dry toner)

(3)Printing speed

	Cassette feed	12 pages/minute (A4/Letter size by cassette feed)
		10.2 pages/minute (Legal size)
(4)	First print time	Approx. 20 seconds
		(A4 size by face-down print delivery from the paper cassette)
(5)	Warm-up (WAIT) time	Max. 1 minute at 20°C (68°F)
(6)	Optical system
	Laser	Semiconductor laser
		Output power : 5mW max.
		Wave length : 780 nm
	Scanning system	Rotating six-faced polygon mirror
(7)	Resolution
	Horizontal	600 dots/inch and high resolution control (HRC)
	Vertical	600 raster lines/inch

I - 1

(8)Printing system

	Photosensitive drum	OPC
	Charging	Charging Roller
	Exposure	Laser scanning system
	Development	Toner projection development system
	Paper feed	Cassette or manual feed
	Image transfer	Roller method
	Separation	Natural(utilizing a small drum radius), Static charge eliminator
	Fixing	Heated fixing roller
	Toner supply	Included in the replaceable EP-ED cartridge
	Life expectancy	6000 pages/cartridge
(9)	Paper
	Cassette feed	Plain paper for Letter, Legal, A4, ISO B5, A5, ISO B6, A6,
		Executive (A4 or letter size paper with the print density set at
		level 8 with 4% coverage, recommended: 60 g/m2									105 g/m2)
		and Envelope (com10, monarch, C5, DL, ISO B5)
	Multi-purpose Tray	Plain paper of 90 x 148 mm							216 x 356 mm (recommended:
		60g/m2				135 g/m 2, overhead projector (OHP) film, postcards,
		label stock and envelopes (specified sizes)
(10) Cassette (Tray 1)
	Universal cassette	A4, Letter, Legal, ISO B5, Executive, A5, ISO B6, and A6
	Maximum load height	55 mm (500 sheets of 80 g/m2							paper)
	Feedable paper type	60		105 g/m 2
	Envelopes	40 envelopes
(11) Print delivery		Face-down or (face-up)
(12)	Print delivery tray capacity
	Face-down	250 sheets (80 g/m2 )
	Face-up	Discharge only

I - 2

(13) Effective printing area

E	A
E	C	E
	Printable area
B	D
	E

Figure 1.1 Printable Area

Effective printable area is referred to as a area within which is guaranteed the printing of all interface signal data on a hard copy without any omission.

The tables below shows the effective printable area for each paper size.

Table 1.1 Plain Paper

SIZE	A (mm)	B (mm)	C (mm)	D (mm)	E (mm)
A 4	210.0	297.0	203.2	288.5	3.39 ± 1.0
Letter	215.9	279.4	207.4	270.9	4.23 ± 1.0
Legal	215.9	355.6	207.4	347.1	4.23 ± 1.0
B 5 (ISO)	176.0	250.0	167.5	241.5	4.23 ± 1.0
Executive	184.2	266.7	175.7	258.2	4.23 ± 1.0
A 5	148.0	210.0	139.5	201.5	4.23 ± 1.0
B 6 (ISO)	125.0	176.0	116.5	167.5	4.23 ± 1.0
A 6	105.0	148.0	96.5	139.5	4.23 ± 1.0

Table 1.2 Envelope

SIZE	A (mm)	B (mm)	C (mm)	D (mm)	E (mm)
COM-10	104.8	241.3	96.3	232.8	4.23 ± 1.0
MONARCH	98.4	190.5	89.9	182.0	4.23 ± 1.0
DL	110.1	221.0	101.6	212.5	4.23 ± 1.0
C5	162.2	228.6	154.1	220.1	4.23 ± 1.0
B5 (ISO)	176.0	250.0	167.5	241.5	4.23 ± 1.0

(The sizes above are nominal sizes according to ISO.)

An A4 sheet accepts 80 PICA-pitch characters (203.2mm).

I - 3

(14) Standard interfaces	Automatic interface selection
	•	Centronics, Bi-directional parallel
	•	RS-232C serial
	Baud rate		:	150, 300,1200, 2400, 4800, 9600
				19200, 38400, 57600 bps
	Stop bit		:	1 bit
	Start bit		:	1 bit or 2 bits
	Data length		:	7 bits or 8 bits
	Parity		:	Odd, Even, or None
	Protocol		:	Xon/Xoff or DTR
(15) Emulation	Automatic emulation selection

•HP Laser Jet 4 (PCL Level 5e)

•EPSON FX-850

•IBM Proprinter XL

•BR-Script level 2 (PostScript language emulation interpreter)

•HPGL

(16) CPU				79R3041 (20MHZ)
(17) Resident fonts				75 scalable fonts and 12 bitmapped fonts
		HP Laser Jet 4, EPSON FX-850, IBM Proprinter XL
		Scalable Fonts:
		Intellifont Compatible Fonts:			Windows 3.1 Compatible Fonts:
		•	Albertville, Extrabold		•	Tennessee Roman, Italic, Bold,
		•	Antique Oakland, Oblique, Bold			Bold Italic
		•	Brougham, Oblique, Bold,		•	Helsinki, Oblique, Bold, Bold Oblique
			Bold Oblique		• BR Symbol
		• Cleveland Condensed			• W Dingbats
		•	Connecticut		BR-Script Fonts:
		•	Guatemala Antique, Italic, Bold,
					•	Atlanta Book, Book Oblique, Demi,
			Bold Italic
						Demi Oblique
		•	Letter Gothic, Oblique, Bold
					•	Copenhagen Roman, Italic, Bold,
		•	Maryland
						Bold Italic
		•	Oklahoma, Oblique, Bold,
					•	Portugal Roman, Italic, Bold, Bold Italic
			Bold Oblique
					•	Calgary Medium Italic
		•	PC Brussels Light, Light Italic, Demi,
					Brother Original Fonts:
			Demi Italic
					•	Bermuda Script
		•	PC Tennessee Roman, Italic, Bold,
					• Germany
			Bold Italic
					• San Diego
		•	Utah, Oblique, Bold, Bold Oblique
					• US Roman
		•	Utah Condensed, Oblique, Bold,

Bold Oblique

Bitmapped Fonts (Portrait and Landscape):

•Letter Gothic 16.66 Medium, Italic, Bold, Bold Italic

•OCR-A

•OCR-B

I - 4

	BR-Script Level 2 Mode
	Scalable Fonts:
	•	Atlanta Book, Book Oblique, Demi,	•	Albertville, Extrabold
		Demi Oblique	•	Antique Oakland, Oblique, Bold
	•	Brussels Light, Light Italic, Demi,	•	Cleveland Condensed
		Demi Italic	•	Conecticut
	•	Brougham, Oblique, Bold, Bold Oblique	•	Guatemala Antique, Italic, Bold, Bold Italic
	•	Helsinki, Oblique, Bold, Bold Oblique	•	Letter Gothic, Oblique, Bold
	•	Helsinki Narrow, Oblique, Bold,	•	Maryland
		Bold Oblique	•	Oklahoma, Oblique, Bold, Bold Oblique
	•	Copenhagen Roman, Italic, Bold,	•	Utah, Oblique, Bold, Bold Oblique
		Bold Italic	•	Utah Condensed, Oblique, Bold,
	•	Portugal Roman, Italic, Bold, Bold Italic		Bold Oblique
	•	Tennessee Roman, Italic, Bold, Bold Italic	•	Bermuda Script
	•	Calgary Medium Italic	•	Germany

	• BR Symbol						• San Diego
	• BR Dingbats						• US Roman
(18)	RAM	2M bytes (expandable to 26M bytes)
(19)	Font cartridge/card slots	Two slots
		One font cartridge slot and one font card slot
(20)	Power souse	USA and Canada						: AC 110 to 120 V, 60 HZ
		Europe and Australia						:		AC 220 to 240 V, 50 HZ
(21)	Power consumption	Printing		:		500 WH or less
		Stand-by		:		80 WH or less
		Sleep		:		20 WH
(22)	Noise	Printing		:		49 dB A or less
		Stand-by		:		40 dB A or less
(23)	Dimensions (W x H x D)	371.6 x 326.5 x 393 mm (14.6 x12.9 x 15.5 inches)
(24)	Weight	Approx. 15 kg (32.6 Ibs)
(25)	Environmental conditions
	Operating	Temperature					10 ~ 32.5°C
	environment	Relative humidity					20 ~ 80%RH
							(No condensation allowed)
		Air pressure					613 ~ 1013 hPa
							(0 ~ 2,500 m above sea level)
	Non-operating	Temperature					0 ~ 35°C
	environment	Relative humidity					10 ~ 80%RH
							(No condensation allowed)
	Storage conditions
	• Printer	Temperature
		Normal (total storage time x 9/10)
		0 ~ 35°C
		Severe (total storage time x 1/10)
		High						Low
		35°C ~ 60°C -20°C ~ 0°C
		Temperature change (within 3 minutes)
		High						Low
		60°C				15°C		-20°C			25°C
			I - 5

Relative humidity

Normal (total storage time x 9/10) 35 ~ 85%RH

Severe (total storage time x 1/10) High Low

85 ~ 95%RH 10 ~ 35%RH

Air pressure 613 ~ 1013 hPa

Total storage time 0.5 years

• EP-ED cartridge	Temperature
	Normal (2.45 years max.)
	0 ~ 35°C
	Severe (0.05 years max.)
	High	Low
	35°C ~ 40°C	-20°C ~ 0°C

Temperature change (within 3 minutes) High Low

40°C15°C -20°C 25°C

Relative humidity

Normal (2.45 years max.) 35 ~ 85%RH

Severe (0.05 years max.) High Low

85 ~ 95%RH 10 ~ 35%RH

Air pressure 613 ~ 1013 hPa

Maximum total storage time: 2.5 years including used time

3.SAFETY INFORMATION

3.1 Laser Safety (110 ~ 120V Model only)

This printer is certified as a Class 1 laser product under the US Department of Health and Human Services (DHHS) Radiation Performance Standard according to the Radiation Control for Health and Safety Act of 1968. This means that the printer does not produce hazardous laser radiation,

Since radiation emitted inside the printer is completely confined within the protective housings and external covers, the laser beam cannot escape from the machine during any phase of user operation.

I - 6

3.2 CDRH Regulations (110 ~ 120V Model only)

The center for Devices and Radiological Health (CDRH) of the US Food and Drug Administration implemented regulations for laser products on August 2, 1976. These regulations apply to laser products manufactured from August 1, 1976. Compliance is mandatory for products marketed in the United States. The label shown below indicates compliance with the CDRH regulations and must be attached to laser products marketed in the United States.

MANUFACTURED :

BROTHER INDUSTRIES, LTD.

15-1, Naeshiro-cho, Mizuho-ku Nagoya 467, Japan. This product complies with FDA radiation performance standards , 21 CFR chapter 1 subchapter J.

Figure 1.2

Caution: Use of controls, adjustments or performance of procedures other than those specified in this manual may result in hazardous radiation exposure.

3.3 Additional Information

When servicing or adjusting the optical system of the printer, be careful not to place screwdrivers or other reflective objects in the path of the laser beam. Be sure to take off any personal accessories such as watches and rings before working on the printer. A reflected beam, though invisible, can permanently damage the eyes.

Since the beam is invisible, the following label is attached to the inside of covers where danger of exposure to laser radiation exist.

Figure 1.3

I - 7

4.PARTS OF THE PRINTER

4.1 External Views

1	Upper cover	9	AC inlet
2	Control panel	10	Face-up print delivery port
3	MP tray	11	Fan outlet port
4	Tray 1	12	Rating label
5	Tray 2 (Option)	13	Optional I/O slot
6	Font card slot	14	RS-232C interface connector
7	Font cartridge slot	15	Centronics interface connector
8	Power switch	16	Optional interface connector

11		1	10
			15
		2
			13
		3
		8	14
		5	16
		4	12
	6	7	9

Figure 1.4

I - 8

4.2 Cross Sectional View

1	2	3	4	5
				6
				7
14
13
				8
12
11
		10		9

1	Registration rollers	9	Low-voltage power supply assy
2	EP-ED cartridge	10	High-voltage power supply assy
3	Photosensitive drum	11	Paper cassette (Tray 1)
4	Laser scanner unit	12	Pick-up rollers
5	Transfer unit	13	MP tray
6	Face-down tray	14	Control panel

7Print-delivery path

8Fixing unit

Figure 1.5

I - 9

5.STORAGE AND HANDLING OF EP-ED CARTRIDGES

An EP-ED cartridge is influenced by the storage conditions even if it is sealed in its package, so its life depends on the way in which it is used or stored. EP-ED cartridges should be handled carefully.

5.1 Storage of Sealed EP-ED Cartridges

When storing sealed EP-ED cartridges in a warehouse or workshop, the storage conditions shown in (25) Environmental conditions on Page 1-5 must be met. Follow the instructions below:

1)Avoid direct sunlight.

2)Do not store cartridges on a surface that is subject to vibration.

3)Do not hit or drop the packages containing cartridges.

4)The cartridges should be stored horizontal when they are removed from the body (with their label side upside).

5)Avoid putting the cartridges near a CRT screen, a disk or a floppy disk (to keep their data from being destroyed).

5.2Storage of Unsealed EP-ED Cartridges

Each EP-ED cartridge contains a photosensitive drum that has an organic photoconductor (OPC) which deteriorates when exposed to strong light. It also contains toner. The user, therefore, should be fully informed about the correct storage and handling of EP-ED cartridges.

(1)Storage requirements

1)Avoid places exposed to direct sunlight or near a window. Do not leave an EP-ED cartridge in a car in warm or hot weather even if it is in its storage box.

2)Avoid places with a too-high or too-cool temperature and/or humidity. Also avoid places exposed to sudden temperature or humidity changes (such as near an air conditioner outlet).

3)Avoid dusty places or places exposed to ammonia fumes or other harmful fumes.

4)Do not store an EP-ED cartridge in a temperature above 40°C.

(2)EP-ED cartridge life

The effective life of an EP-ED cartridge is 2.5 years from the date of manufacture (printed on the cartridge.) The expiry year and month (date of manufacture plus 2.5 years) is shown on the EP-ED cartridge box. An EP-ED cartridge used after the expiry may produce low-quality printing, so a cartridge should be used within the stated period.

I - 10

CHAPTER II THEORY OF OPERATION

This chapter describes the printer functions, the relationship between the electrical systems and mechanical systems, and the timing of operations. Striped conduits () indicate mechanical linkages; solid thin arrows ( ) appearing with a signal name indicate the transmission of single control signals and outlined thick arrows () indicate the transmission of groups of signals.

1. BASIC OPERATIONS

1.1 Mechanical Configuration

The printer functions can be divided into four blocks: the laser/scanner system, the image formation system, the paper pick-up/feed system and the control system.

			Font cartridge/card				Optional I/O
	Expansion memory						(MIO)
	(SIMM)

Main PCB

Control panel

CONTROL SYSTEM

IMAGE FORMATION SYSTEM

	Photosensitive drum	Laser/scanner
		unit
Cleaning unit	Developing
	unit

										LASER/SCANNER
										SYSTEM
							Transfer
							separation
							unit
rollersDelivery		unitFixing		Feeder						MP tray
										Tray 1
										Tray 2
										(Option)

PAPER PICK-UP/FEED SYSTEM

Figure 2.1

II - 1

External Device

1.2 Main Drive

The power necessary for driving the printer is supplied by the main motor, the paper feed motor and the scanner motor.

The main motor is controlled by the main motor drive signal (MDRIVE) output from the main PCB, and the paper feed motor is controlled by the paper feed motor drive signal output from the main PCB, and the scanner motor is controlled by the scanner motor drive signal (SDRIVE) output from the main PCB.

Main motor

Main motor drive signal (MDRIVE)

Main PCB

Drum gear

Photosensitive drum

	Fixing unit	Paper delivery
		rollers

Paper feed motor

Paper feed motor drive signal

MP tray pick-up roller solenoid drive signal (MPSOL)

				MP tray pick-up				MP tray
				roller solenoid				pick-up roller

Tray1 pick-up roller solenoid drive signal (PUCL1)

Tray1 pick-up roller solenoid

Tray1 pick-up roller

Scanner motor drive signal (SDRIVE)

				Note: There are cases, in the following pages, that
			Scanning mirror	a main motor is referred to as a DC motor, but
				they are identical.

Scanner motor

Scanner unit

Figure 2.2

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1.3 Basic Sequence of Operations

Timing for two consecutive prints on A4 paper.

	Power on	Print
	WAIT	STBY			PRINT	STBY
Ready lamp
						170°C
Fixing heater	170°C	control			190°C control	control
Main motor
Scanner motor
Paper feed
motor
Pick-up roller	0.2 sec		0.2 sec	2.5 sec	2.3 sec
solenoid
Laser diode
Registration				4.24 sec
sensor

Figure 2.3

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2. LASER/SCANNER SYSTEM

To external device

Main PCB

SBD DATA VOFF

Scanner driver
Collimator lens	Scanning mirror
Cylindrical lens
Optical sensor	Scanner motor
	Focusing lenses
	Beam detect mirror

Figure 2.4

In response to the print signal transmitted from the external device, the main PCB generates the drive signals (DATA,VOFF) for the laser diode and sends the signals to the scanner unit.

The laser diode in the scanner unit generates a laser beam modulated by DATA.

The modulated laser beam is aligned into a parallel beam by a collimator lens and a cylindrical lens and then brought to the scanning mirror which is rotating at a constant speed.

The laser beam reflected by the scanning mirror focuses on the photosensitive drum via the focusing lenses arranged in front of the scanning mirror.

The path of the beam coming through the focusing lenses is reflected by the reflective mirror.

As the scanning mirror rotates at a constant speed, the laser beam scans the photosensitive drum at a constant speed.

As the photosensitive drum rotates at a constant speed and the laser beam scans the drum, an images is formed on the drum.

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3. IMAGE FORMATION SYSTEM

3.1 Outline

The image formation system is the main part of the printer. The print information, after input from the video controller circuit into the engine controller circuit as a TVDO signal, forms a toner image on the photosensitive drum.

Then the toner image is transferred onto the paper by the transfer charging roller. The image formation system is composed of the photosensitive drum the charging unit, the developing unit and the cleaning unit.

3.2 Printing Process

The major part of the image formation system is contained in the cartridge, as shown in Figure 2.5.

Laser beam	Cartridge
Primary charging roller	Blade
Cleaning blade	Developing cylinder
Photosensitive drum	Paper
	Transfer charging roller

Static charge eliminator

Figure 2.5

The cartridge used by the printer has a seamless photosensitive drum with the structure shown in Figure 2.6. The outer layer of the drum consists of an organic photoconductor (OPC); the base is aluminum.

The printing process can be divided into five major stages:

Photoconductive layer

Base

Figure 2.6

1.Electrostatic latent image formation stage Step 1 Primary charge (-)

Step 2 Scanning exposure

2.Developing stage Step 3 Development

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3.Transfer stage Step 4 Transfer (+) Step 5 Separation

4.Fixing stage Step 6 Fixing

5.Drum cleaning stage Step 7 Drum cleaning

	Electrostatic latent image
	formation stage
	2. Scanning exposure
	1. Primary charge
	3. Develop
	ment
Drum cleaning stage	7. Drum cleaning

Paper path

Direction of drum rotation

Developing stage

	Fixing stage
	5. Separa-	4. Transfer	Registration	Multi-purpose tray feed
	tion

Print delivery

6. Fixing

Transfer stage

Cassette feed

Figure 2.7

3.2.1Electrostatic latent image formation stage

This stage has two steps, which together produce a pattern of electrical charges on the photosensitive drum.

At the end of the stage, negative charges remain in the unexposed ”dark” area. Charges are absent from the ”light” areas, where the laser beam struck (exposed) the drum surface.

Since this image of negative charges on the drum is invisible to the eye, it is called an ”electrostatic latent image”.

Surface potential (V)

0			Time (t)
-100
	Exposed
	area
-500
		Unexposed
		area
Primary	Scanning	Transfer	Primary
charge	exposure	(step 4)	charge
(step 1)	(step 2)		(step 1)

Figure 2.8

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Step 1 Primary charge

Primary charging roller

AC bias

Photosensitive drum

DC bias

Figure 2.9

As preparation for latent image formation, a uniform negative potential is applied to the photosensitive drum surface. The printer uses the charging method that directly charges the drum for the primary charge.

The primary charging roller consists of conductive rubber. In addition to DC bias, AC bias is applied to the primary charging roller to keep the potential on the drum surface uniform. This DC bias is changed with the developing DC bias.

This charging method has advantages such as lower applied voltage, less ozone generation, etc., compared with the corona charge system.

Step 2 Scanning exposure

Laser beam

_ _ _

++ +

Unexposed area		Exposed area

Figure 2.10

When the laser beam scans the drum surface, it causes the charge to be neutralized in the areas struck by the beam. Areas on the drum with no charge form the electrostatic latent image.

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3.2.2Developing stage

Development places particles of toner onto the areas of the drum that have been cleared of charge by the laser beam. This makes a visible image. This printer uses the toner projection development method with a single-component toner.

Step 3 Development

Blade

Photo-	Stirrer
sensitive
drum
AC bias	Developing cylinder
	Cylinder
	Magnet

DC bias

Figure 2.11

Note: The charges on the light areas on the photosensitive drum are shown as positive in this figure. Actually they are negative, but they are more positive than the developing cylinder and explanation is simplified by regarding them as positive.

As shown in Figure 2.11, the developing unit consists of a developing cylinder and rubber blade. The developing cylinder rotates around a fixed internal magnet. The single-component toner consists of magnetite and a resin binder, and is held to the cylinder by magnetic attraction. The toner is an insulator, and acquires a negative charge by friction due to the rotation of the cylinder.

The areas on the drum that were exposed to the laser beam have a higher potential (are less negative) than the negatively charged toner particles on the developing cylinder. When these areas approach the cylinder, the potential difference projects the toner particles onto them. This is called toner projection, and the latent image on the drum becomes visible.

Developing cylinder surface potential

	+V		Drum surface
			potential
	0
(V)			(exposed area)
			DC bias
Voltage
	-V		Drum surface
		Time t	potential
			(unexposed area)

Figure 2.12

An AC bias is applied to the developing cylinder to help project the toner particles to the drum surface and improve the contrast of the printed image. The center voltage of the AC bias (1600 Vp-p) varies with the DC bias voltage.

The IMAGE DENSITY ADJUSTMENT signal (sent from the Engine CPU to the high-voltage power supply) changes the DC bias, and thus the potential difference between the cylinder and drum. This changes the density of the print.

This printer has a stirring mechanism to supply toner in the cartridge smoothly to the cylinder.

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3.2.3Transfer stage

In the transfer stage, the toner image is transferred from the drum surface to the paper.

Step 4 Transfer

Photo-
sensitive	Paper
drum

Transfer charging roller

Figure 2.13

A positive charge applied to the back of the paper attracts the negatively charged toner particles to the paper. The printer accomplishes transfer by using the charging roller method. Advantages compared with the corona transfer method are as follows:

•Low transfer voltage that is less than half that for corona transfer.

•Less ozone generation.

•The paper is supported by the transfer charging roller and photosensitive drum, so feed is more stable.

Reference:

If the image on the photosensitive drum is not completely transferred to the paper due to jamming, etc., the toner may adhere to the transfer charging roller. The printer removes the toner from the transfer charging roller by switching the transfer voltage between positive and negative in sequence. During wait, initial rotation, and last rotation, the printer sets the primary DC voltage to zero, and sets the charge on the drum to zero. In this case, the transfer voltage is made negative to remove the negatively-charged toner on the transfer charging roller to the drum. The transfer charging roller is thus cleaned.

Step 5 Separation

Photosensitive

drum Paper

Static charge eliminator

Transfer charging roller

Figure 2.14

The stiffness of the paper causes it to separate from the drum. (Curvature separation)

To stabilize the paper feed and prevent small white circles from appearing in the printed image at low temperature and humidity, the charge on the back of the paper is reduced by the static charge eliminator after transfer.

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3.2.4Fixing stage

The toner image transferred to the paper in the transfer stage is held only by electrostatic attraction and slight physical adhesion, so even a light touch will smear the image.

In the fixing stage, the toner image is fixed by heating the paper and applying pressure. This fuses the toner particles to the paper to make a permanent image.

Step 6 Fixing

Halogen heater

Upper fixing roller

Toner

Paper

Lower fixing roller

Figure 2.15

The upper roller surface is PFA-coated. The upper and lower roller surfaces are grounded via a diode to prevent the negative potential of the upper roller becoming higher than that of the lower roller, resulting in the toner being drawn to the lower roller, and adhering to the lower roller surface.

3.2.5Drum cleaning stage

In the transfer stage, not all the toner is transferred to the paper. Some remains on the photosensitive drum. This residual toner is cleaned off in the drum cleaning stage so that the next print image will be clear.

Step 7 Drum cleaning

Cleaning blade

Photosensitive drum

Cleaner container

Sweeper strip

Figure 2.16

Prior to the next printing, the residual toner on the drum surface is scraped away by the cleaning blade to clean the drum surface. The removed toner is collected in the cleaner container.

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3.3 Operation

When the engine controller circuit receives a print signal (PRINT) or a pre-feed signal (PRFD) from the video controller circuit, the engine controller circuit drives the main motor to rotate the photosensitive drum.

After the drum surface is charged negatively by the primary charge roller, the laser beam modulated by a DATA signal scans the drum surface to from a latent image on the drum.

The latent image formed on the drum surface is converted into a visible image by the toner on the developing cylinder and then image is transferred onto the paper by the transfer roller unit. Then the residual toner is removed from the drum surface with the cleaner blade.

The cartridge also has a toner sensor. When the output from this sensor falls below a certain level, it warns that the EP-ED cartridge will be out of toner with an alarm.

Scanner unit

Scanner motor drive signal (SDRIVE)

Laser diode drive signal (DATA)

Reflection mirror

Laser beam

EP-ED cartridge

Transfer roller

Main

PCB

Primary charge (AC) drive (HV1AC) Primary charge (DC) drive (HV1DC) Developing bias (AC) drive (DBAC) Developing bias (DC) drive (DBDC)

Transfer charger 1 drive (HVT1) Transfer charger 2 drive (HVT2) Transfer charger 3 drive (HVT3) Transfer charger 4 drive (HVT4)

Toner sensor signal 1 (TONER 1) Toner sensor signal 2 (TONER 2)

High-voltage power supply PCB

Figure 2.17

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4. PAPER PICK-UP/FEED SYSTEM

4.1 Outline

If a tray1 paper pick-up roller solenoid drive signal (PUCL1) is input to the circuit while the paper feed motor is rotating, the paper pick-up solenoid comes on and the paper pick-up roller solenoid is engaged. As a result, the paper pick-up roller rotates to feed paper down to the photosensitive drum.

The paper position is controlled by the registration sensor so that the leading edge of the paper is aligned with the leading edge of the image on the photosensitive drum. After this operation, the paper is deliveried to the face down tray via the fixing unit. Paper ejection is detected by the paper ejection sensor; if printed paper has not reached or not cleared the paper ejection sensor in a specified time, the printer judges that a paper jam has occurred. In this case a paper jam is noticed to the external devise by a status signal.

MP tray	paper empty sensor
Tray paper empty sensor	Tray1 Pick-up roller solenoid

Fixing rollers Transfer roller

MP tray paper empty sensor signal (PEMP)

MP tray Pick-up roller solenoid

MP tray pick-up roller solenoid drive signal (MPSOL)

Paper feed motor drive signal

Paperfeed motor

Tray1 pick-up roller solenoid drive signal (PUCL1)

Tray1 paper empty sensor signal (PETRAY1)

	Registration sensor	Registration sensor signal (REGIST)	PCB
		Main motor drive	Main
		signal (MDRIVE)
sensorejectionPaper	Photosensitive drum	Main motor
	Paper ejection sensor signal (EJECT)

Figure 2.18

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4.2 Cassette Feed

When the fixing rollers reach the specified temperature while a cassette with paper is in the printer, the READY lamp changes from flashing to lighting.

When the engine controller circuit receives PRNT or PRFD signal from the video controller circuit, the paper feed motor starts rotation. About 0.2 seconds later, the printer actuates the tray1 pick-up roller solenoid and the pick-up roller makes one rotation. This feeds paper to the photosensitive drum.

Timing chart for the pick-up one sheet

PRNT or PRFD

	STBY		PRINT	STBY
Main motor
Paper empty
sensor
Paper feed
motor
Registration		2.3 sec	4.24 sec
sensor
Paper ejection			2.90 sec
sensor
Pick-up roller	0.2 sec	0.2 sec
solenoid

Figure 2.19

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4.3 MP Tray Feed

The timing of the MP tray feed is identical to the timing of the cassette paper feed except for the following points:

(1)The paper empty sensors are different. Cassette feed : Tray1 paper empty sensor

MP tray feed : MP tray paper empty sensor

(2)The pick-up roller solenoids are different. Cassette feed : Tray1 pick-up roller solenoid

MP tray feed : MP tray pick-up roller solenoid

PRNT or PRFD

	STBY	PRINT	STBY
Main motor
Paper empty
sensor
Paper feed
motor
Registration		1.12 sec
sensor
Paper ejection
sensor
Pick-up roller	0.2 sec	0.2 sec
solenoid

Figure 2.20

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