Epson LC7211TM Service Manual

DOT MATRIX PRINTER

LC-7211

TECHNICAL MANUAL

[ THIRD EDITION ]

NOTICE

form whatsoever, without STAR’s express permission is forbidden.

• The contents of this manual are subject to change without notice.

• All efforts have been made to ensure the accuracy of the contents

of this manual at the time of going to press. However, should any errors be detected, STAR would greatly appreciate being informed of them.

• The above notwithstanding, STAR can assume no responsibility

for any errors in this manual.

INTRODUCTION

This manual is an introduction to the LC-7211. It is designed for use as a reference for periodic inspections and maintenance procedures to be executed by service personnel. It is not intended for the general user. Users of this manual should have a basic knowledge and understanding of the English language.

• This manual is divided into the following sections:

Chapter 1 General Specifications Chapter 2 Theory of Operation Chapter 3 Adjustments Chapter 4 Parts Replacement Chapter 5 Maintenance and Lubrication Chapter 6 Troubleshooting Chapter 7 Parts List

1 2

3 4

• First edition : Dec. 1995

Second edition : Aug. 1996 Third edition : Aug. 1997

5 6 7

CHAPTER 1

GENERAL SPECIFICATIONS

1. General Specifications..........................................................................................3

2. External Appearance and Composition ..............................................................5

3. Control Panel .........................................................................................................7

3-1. Switch Combination Functions ............................................................................. 7

3-2. EDS Mode Settings................................................................................................. 8

4. Parallel Interface....................................................................................................9

4-1. General Specifications ........................................................................................... 9

4-2. Connector Signals .................................................................................................. 9

5. Serial Interface (optional) ...................................................................................10

5-1. General Specifications ......................................................................................... 10

5-2. Connector Signals and Functional Descriptions............................................... 10

5-3. DIP Switch Settings .............................................................................................. 11

6. EE-PROM Mode ...................................................................................................12

6-1. Outline ................................................................................................................... 12

6-2. Explanation of Special Control Codes................................................................ 12

6-3. EE-PROM MAP ...................................................................................................... 13

6-4. Rewriting the EE-PROM ....................................................................................... 16

1. General Specifications

Printing System Serial Impact Dot-Matrix Printing Speed Pitch Draft(cps/dpi) NLQ(cps/dpi)

Pice (10cpi) 225/120H 56/240H Elite (12cpi) 270/120H 67/240H Condensed pica (17cpi) 191/240H 95/240H Condensed elite (20cpi) 225/240H 112/240H H:half-dot

Print Direction Draft: Bi-directional logic seeking

NLQ: Uni-directional/bi-directional logic seeking (selectable) Bit-Image: Uni-directional/bi-directional logic seeking (selectable)

Print Head Number of pins: 9

Life: 200 million dots/pin (adjustment lever position 1 to 3)

100 million dots/pin (adjustment lever position 4 to 8)

Line Spacing 1/6", 1/8"

7/72", n/72", n/216": software

Character Matrix Pitch Draft NLQ

Pica (10cpi) 9×11 18×23 Elite (12cpi) 9×918×19 Condensed Pica (17cpi) 9×11 18×12 Coodensed elite (20cpi) 9×918×10

Environment Operating temperature: 41°F to 95°F (5°C to 35°C)

Storage temperature: –22°F to 149°F (–30°C to 65°C) Operating humidity: 30% to 80% (noncondensing) Storage humidity: 20% to 90% (noncondensing)

Paper Cut-sheet

Paper width: 5.5" to 12" / 140 to 305mm Paper length: 5.5" to 11"/ 140 to 280mm Paper weight (1-ply): 14 to 42 lbs / 52 to 156 g/m2 / 45 to 135 kg Multi-part: 11 to 14 lbs / 40 to 52 g/m2 / 34 to 45 kg; pressure

sensitive paper

Total thickness: 0.020" / 0.5mm Copies: Original + 6 Fanfold Paper width: 4.5" to 12" / 114 to 305mm Paper weight (1-ply): 14 to 22 lbs / 52 to 81 g/m2 / 45 to 70 kg Multi-part: 11 to 14 lbs / 40 to 52 g/m2 / 34 to 45 kg; pressure

sensitive paper

Total thickness: 0.02" / 0.5mm Copies: Original + 6

– 3 –

Labels Backing sheet: 4.5" to 12" / 114 to 305mm Thickness:

Backing sheet 0.0028" to 0.0035" / 0.07 to 0.09mm Total thickness 0.0075" / 0.19mm max.

Envelope #10 9.4 × 4.1 / 240 × 104mm

Emulation Standard Mode: EPSON ESC/P (9-pin)

IBM Mode: Proprinter III

Interface Standard: Centronics parallel

Option: RS-232C serial

Ribbon Type On-carriage, dedicated

Fabric monochrome ribbon (Black only) Z9HD: Standard type LZ9: Long life type (option)

Ribbon Life Z9HD: 2 million characters (ASCII draft)

LZ9: 4 million characters (ASCII draft)

Power Supply 120V AC +10%/–17%, 230V AC +14%/–13%; 50/60Hz (depending on country of

purchase)

Power Consumption 10W during stand-by

31W during ASCII draft printing

Options SPC-8K Serial-To-Parallel Converter

Weight 16.1lbs/7.3kg

525mm

20.67”

Fig. 1-1 External dimensions

– 4 –

230mm

370mm

14.57”

9.06”

2. External Appearance and Composition

Adjustment lever

Paper guide

Power switch



Front cover

Platen knob

Control panel

Fig. 1-2 Front view of the Printer

Interface connector

Fig. 1-3 Rear view of the Printer

– 5 –

Release laber

Fig. 1-4 Front cover removed

Fig. 1-5 Diagram of internal layout

– 6 –

3. Control Panel

3-1. Switch Combination Functions

BANK SW A1

ROMAN

SANSERIF

COURIER

PRESTIGE

ORATOR

QUIET

FONT MODE LF ON LINE

Hex-Dump Long test Short test 1

MICRO FEED

Short test 2

EDS mode

POWER

DRAFT

QUIET

Dot-adjust mode

= Push = Hold

EDS mode

Aging mode

Tear off Set/Eject/Park Off-LineQuiet

Mode LF/Set On-LineFont

Panel macro Form feed

Backward Forward Micro feed

Set TOF

Buffer clear and All reset

Auto loading position change mode

Bank Switch On/Off Exit

Left Right Next Exit

POWER-ON

ON-LINE

OFF-LINE

EDS MODE

DOT ADJUSTMENT MODE

Paper

Backward Foward Cancel

Set

Save

Factory settings

AUTO LOADING POSITION CHANGE MODE

– 7 –

3-2. EDS Mode Settings

Bank Switch Function ON OFF

A 1 Emulation Standard / EPSON IBM

B 1 Graphics Direction Bi-directional Uni-directional

C 1, 2 Print Mode

D 1,2,3,4 Page Length

E 1,2,3,4,5 Code Page (CT=Graphics, IBM #1, #2)

F 1, 2, 3, 4, 5 LQ Font Selection

2 Character Table (CT) Standard / EPSON mode Graphics Italics

IBM mode IBM #2 IBM #1 3 RAM Usage Input Buffer Download Buffer 4 (Not used) 5 Paper Out Detector Enabled Disabled 6 (Not used)

2 Auto Tear-off (Long) Disabled Enabled 3 Line Spacing 1/6" 1/8" 4 Auto LF with CR Disabled Enabled 5 Zero Style Normal Slashed 6 Strobe Timing Normal Reverse

Draft ON ON NLQ ON OFF (Not used) OFF ON (Not used) OFF OFF

3,4,5 Print Pitch

10cpi ON ON ON 20cpi OFF OFF ON 12cpi OFF ON ON Proportional ON ON OFF 17cpi ON OFF ON

6 Quiet Disabled Enabled

11"/Letter ON ON ON ON 14"/Legal OFF ON OFF ON 8" OFF ON ON ON 10.5"/Executive ON OFF OFF ON

11.7"/A4 ON OFF ON ON 7.25"/Executive OFF OFF OFF ON 12" OFF OFF ON ON 3.5" ON ON ON OFF

8.5"/Letter ON ON OFF ON 5.5" OFF OFF ON OFF

#437 ON ON ON ON ON #1001 ON ON ON ON OFF #850 OFF ON ON ON ON #737 OFF ON ON ON OFF #860 ON OFF ON ON ON #851 ON OFF ON ON OFF #861 OFF OFF ON ON ON #869 OFF OFF ON ON OFF #863 ON ON OFF ON ON #928 ON ON OFF ON OFF #865 OFF ON OFF ON ON #2001 OFF ON OFF ON OFF #866 ON OFF OFF ON ON #772 ON OFF OFF ON OFF #3840 OFF OFF OFF ON ON #774 OFF OFF OFF ON OFF #3841 ON ON ON OFF ON #3001 ON ON ON OFF OFF #3843 OFF ON ON OFF ON #3002 OFF ON ON OFF OFF #3844 ON OFF ON OFF ON #3011 ON OFF ON OFF OFF #3845 OFF OFF ON OFF ON #3012 OFF OFF ON OFF OFF #3846 ON ON OFF OFF ON #3021 ON ON OFF OFF OFF #3847 OFF ON OFF OFF ON #3031 OFF ON OFF OFF OFF #3848 ON OFF OFF OFF ON #3041 ON OFF OFF OFF OFF #852 OFF OFF OFF OFF ON

International Character Set (CT=Italics)

U.S.A. ON ON ON ON ON Japan ON ON ON OFF ON France OFF ON ON ON ON Norway OFF ON ON OFF ON Germany ON OFF ON ON ON Denmark-2 ON OFF ON OFF ON England OFF OFF ON ON ON Spain-2 OFF OFF ON OFF ON Denmark-1 ON ON OFF ON ON Latin America ON ON OFF OFF ON Sweden OFF ON OFF ON ON Korea OFF ON OFF OFF ON Italy ON OFF OFF ON ON Ireland ON OFF OFF OFF ON Spain-1 OFF OFF OFF ON ON Legal OFF OFF OFF OFF ON

Roman ON ON ON ON ON Prestige OFF OFF ON ON ON Sanserif OFF ON ON ON ON Orator OFF OFF OFF ON ON Courier ON OFF ON ON ON

– 8 –

4. Parallel Interface

4-1. General Specifications

Item Specifications

Interface Centronics-compatible Synchronization System Via externally supplied STROBE pulse I/F Protocol Using ACK and BUSY signals Logic Level Compatible with TTL level

ACK

Data

STROBE

(EDS B-6 : ON)

STROBE

(EDS B-6 : OFF)

BUSY

4.1µs

tttt

t : More than 0.5µs

Fig. 1-6 Timing Charts for Parallel Interface

4-2. Connector Signals

Pin Name Function

1 STROBE Goes low for ≥ 0.5µs when active. 2 DATA0 3 DATA1 4 DATA2 5 DATA3 6 DATA4 7 DATA5 8 DATA6 9 DATA7

10 ACK 10µs low to acknowledge receipt of data. 11 BUSY Printer sets line low when ready to receive data. 12 PAPER High when paper runs out. 13 SELECT High when printer is on-line. 14 AFXT Printer ignores this signal. 15 Not used. 16 SIGNAL GND Signal ground 17 CHASSIS Chassis ground (isolated from signal ground) 18 +5V +5V DC output from printer

19~30 GND Twisted pair ground return

31 RESET Printer is reset when this signal goes low. 32 ERROR Low when printing cannot continue due to error. 33 EXT GND External ground

34~35 Not used

36 SELECT IN Printer ignores this signal.

These signals represent information for the 1st through 8th bit of parallel data, respectively. Each signal is HIGH when data is logical 1, and LOW when logical 0.

– 9 –

5 Serial Interface (optional)

When using the serial interface, the optional Serial-Parallel Converter must be connected to the printer.

5-1. General Specifications

Item Specifications

Interface RS-232C level Synchronization System Asynchronous Baud rate 150 - 19,200 bits per second (BPS) [selectable]

150, 300, 600, 1200, 2400, 4800, 9600, 19200 BPS

Word length

Start bit: 1 bit Data bit: 7 or 8 bits (selectable) Parity bit: Odd, Even or None (selectable) Stop bit: More then 1bit length

Signal polarity

Mark: Logic “1” (–3V to –15V) Space: Logic “0” (+3V to +15V)

Handshaking DTR

XON/XOFF ETX/ACK

Data buffer 8KB (standard)

5-2. Connector Signal and Functional Descriptions

Pin No. Signal name Direction Function

1 GND — 2 TXD OUT 3 RXD IN 4 RTS OUT

5 CTS — 6NC

7 GND —

8~10 NC

11 RCH OUT

12~19 NC

20 DTR OUT

21~25 NC

Printer chassis ground. This pin carries data from the printer. This pin carries data to the printer. Always space. This signal is space when the computer is ready to send data.

The printer does not check this pin. Unused. Signal ground. Unused. The printer sets this signal to space when it is ready to receive data.

This line carries the same signal as pin 20. Unused. The printer sets this signal to space when it is ready to receive data. Unused.

– 10 –

5-3. DIP Switch Settings

Switch ON OFF

All switches are set to ON before the printer leaves the factory.

Baud rate Switch 6 Switch 7 Switch 8

1 8 data bits 7 data bits 2 No parity Parity checked 3 4 5 Odd parity Even parity 6 7 Data transfer rate – see table below 8

150 OFF OFF OFF 300 OFF OFF ON

600 OFF ON OFF 1200 OFF ON ON 2400 ON OFF OFF 4800 ON OFF ON 9600 ON ON OFF

19200 ON ON ON

Handshaking protocols – see table below

Protocol Switch 3 Switch 4

DTR mode ON ON XON/XOFF mode ON OFF ETX/ACK mode OFF ON

– 11 –

6. EE-PROM mode

6-1. Outline

These settings can be changed in the EE-PROM mode by writing data directly to the EE-PROM on the main logic board:

Setting EE-PROM mode

• Send <ESC><SUB>(09)H command.

Canceling EE-PROM mode

• Initialize the printer by sending <ESC>@

6-2. Explanation of special control codes

<ESC>@ Exits printer from EE-PROM mode and initializes the printer. <ESC>M@ Returns all data in the EE-PROM to the factory settings. After the buffer is cleared, the buzzer sounds. If

the printer is powered off before the buzzer sounds, all data in the buffer is not cleared.

If all data is not cleared from the buffer, operation is not guaranteed. Be sure to allow the buzzer to sound before you turn the printer off!

<ESC>MWn

Code Function Address Capacity

<ESC>MW0 <data> Stores data into entire area of EE-PROM. 00H-7FH 128bytes <ESC>MW1nm Stores data (m) into the address (n) nH 1 byte <ESC>MW2<data> Stores auto-start software data into 2CH-54H 41bytes

EE-PROM. 55H-7DH 41bytes

• The data (m) used in the commands above are stored in the specified address in order (n).

• When the data to be stored exceeds the specified capacity, subsequent data are ignored.

• Data are stored in the EE-PROM according to the memory map. (See section 3. EDS mode setting and 6-3. EE-PROM Map.)

• After all data are stored, a beep indicates the completion of storage.

• If the printer is powered off during data storage, data stored before power off are valid, but subsequent operation of the printer is not guaranteed.

Do not power off the printer while data is being stored!

<ESC>MR Dumps all data in the EE-PROM to a hard copy.

For an example of using these control codes, see section 6-4. For the corresponding EE-PROM addresses, see the EE-PROM memory map in section 3-2. EDS mode setting and 6-3 EE-PROM Map.

– 12 –

6-3. EE-PROM MP

Address Function Factory data

00H EDS setting FFH

Bit Function 1 0

b0 Emulation

Character Table

b1 Standard / EPSON mode Graphics Italics

IBM mode IBM #2 IBM #1

b2 RAM Usage Input Buffer b3 (Not used) — — b4 Paper out Detector Enabled Disabled b5 (Not used) — —

01H EDS setting FFH

Bit Function 1 0

b0 Graphics Direction Bi-directional Uni-directional b1 Tear-off Disabled Enabled b2 Line Spacing 1/6" 1/8" b3 Auto LF with CR Disabled Enabled b4 Zero Style Normal Slashed b5 Strobe Timing Normal Reverse

STANDARD/EPSON

IBM

Download Buffer

02H EDS setting FFH

Print Mode Print Pitch

Function b0 b1 Function b2 b3 b4

Draft 1 1 10cpi 1 1 1 NLQ 1 0 12cpi 0 1 1

17cpi 1 0 1 20cpi 0 0 1 Proportional 1 1 0

Bit Function 1 0

b5 Quiet Disabled Enabled

03H EDS setting FFH

Page Length

Function b0 b1 b2 b3 Function b0 b1 b2 b3

11"/Letter 1 1 1 1 14"/Legal 0101 8" 0 1 1 1 10.5"/Executive 1001

11.7"/A4 1 0 1 1 7.25"/Executive 0001 12" 0 0 1 1 3.5" 1110

8.5"/Letter 1 1 0 1 5.5" 0110

– 13 –

Address Function Factory data

04H EDS setting FFH

IBM Code Page (Character Table=Graphics, IBM#1, #2)

Function b0 b1 b2 b3 b4 Function b0 b1 b2 b3 b4

#437 11111 #3841 1 1 1 0 1 #850 01111 #3843 0 1 1 0 1 #860 10111 #3844 1 0 1 0 1 #861 00111 #3845 0 0 1 0 1 #863 11011 #3846 1 1 0 0 1 #864 01011 #3847 0 1 0 0 1 #866 10011 #3848 1 0 0 0 1 #3840 00011 #852 0 0 0 0 1

International Character Set (Character Table=Italics)

Function b0 b1 b2 b3 b4 Function b0 b1 b2 b3 b4

U.S.A. 11111 Japan 1 1 1 0 1 France 01111 Norway 0 1 1 0 1 Germany 10111 Denmark-2 1 0 1 0 1 England 00111 Spain-2 0 0 1 0 1 Denmark-1 11011 Sweden 01011 Korea 0 1 0 0 1 Italy 10011 Ireland 1 0 0 0 1 Spain-1 00011 Legal 0 0 0 0 1

Latin America

11001

05H EDS setting FFH

NLQ Font Selection

Function b0 b1 b2 b3 b4 Function b0 b1 b2 b3 b4

Roman 11111 Prestige 0 0 1 1 1 Sanserif 01111 Orator 0 0 0 1 1 Courier 10111

06H Misalignment correction 60 DPI (F) 80H 07H Misalignment correction 72 DPI (F) 80H 08H Misalignment correction 80 DPI (F) 80H

09H Misalignment correction 90 DPI (F) 80H 0AH Misalignment correction 120 DPI (H) Text 80H 0BH Misalignment correction 120 DPI (H) Bit-image 80H 0CH Misalignment correction 120 DPI (F) 80H 0DH Misalignment correction 144 DPI (H) 80H 0EH Misalignment correction 240 DPI (H) Text 80H 0FH Misalignment correction 240 DPI (H) Bit-image 80H

10H Misalignment correction Multi-part Mode 60 DPI (F) 80H

11H Misalignment correction Multi-part Mode 72 DPI (F) 80H

12H Misalignment correction Multi-part Mode 80 DPI (F) 80H

13H Misalignment correction Multi-part Mode 90 DPI (F) 80H

14H Misalignment correction Multi-part Mode 120 DPI (H) Text 80H

15H Misalignment correction Multi-part Mode 120 DPI (H) Bit-image 80H

16H Misalignment correction Multi-part Mode 120 DPI (F) 80H

17H Misalignment correction Multi-part Mode 144 DPI (H) 80H

18H Misalignment correction Multi-part Mode 240 DPI (H) Text 80H

19H Misalignment correction Multi-part Mode 240 DPI (H) Bit-image 80H

– 14 –

Address Function Factory data

1AH, 1BH Top Margin in Auto-loading Tractor 48H

00H

1CH, 1DH Top Margin in Auto-loading Friction 48H

00H

1EH~21H Macro Set EPSON 00H

00H

22H~25H Macro Set IBM 00H

00H

26H, 27H TEAR OFF (Short) 00H

80H

28H, 29H TEAR OFF (Long) 00H

80H

2AH, 2BH Initial Condition Area FFH

FFH

2CH~54H Auto Start Area EPSON (41 byte) 00H

00H

55H~70H Auto Start Area IBM (41 byte) 00H

00H

7EH FF Control Code (Space 00H / Null 0FH) 00H

7FH EE-PROM Check Code 01H

– 15 –

6-4. Rewriting the EE-PROM

Follow this procedure to rewrite the EE-PROM. (1) Turn the printer on. (2) Load a BASIC disk in the computer. (3) Turn the computer on. (4) Set a sheet of paper in the printer, and press the ON LINE switch. (5) Enter the program listed below and run the program.

10 LPRINT CHR$(27);CHR$(26);CHR$(&H09) 20 LPRINT CHR$(27);”MW1";CHR$(&H01);CHR$(&HFB) 30 LPRINT CHR$(27);”MR”

BASIC Program Code What It Does

10 LPRINT CHR$(27);CHR$(26);CHR$(&H09) Enters the EE-PROM mode. 20 LPRINT CHR$(27);”MW1"; Starts rewriting the EE-PROM. CHR$(&H01); Address data from &H01 will show

EDS mode from the EE-PROM memory map.

CHR$(&HFB) Data from &HFB will change the Line

spacing from 1/6" to 1/8".

30 LPRINT CHR$(27);”MR” Dumps all EE-PROM data to hexadeci-

mal.

(6) To complete the setting, turn the printer off.

– 16 –

CHAPTER 2

THEORY OF OPERATION

1. Block Diagram (Main logic Board).....................................................................19

2. Main Logic Board ................................................................................................20

2-1. General Flow Chart............................................................................................... 20

3. Power Supply Circuit ..........................................................................................21

4. Mechanisms.........................................................................................................22

4-1. Print Head Mechanism ......................................................................................... 22

4-2. Print Head Carrying Mechanism ......................................................................... 23

4-3. Ink Ribbon Feed Mechanism ............................................................................... 24

4-4. Paper Feed Mechanism........................................................................................ 25

4-5. Detectors ............................................................................................................... 26

1. Block Diagram (Main logic Board)

The block diagram of this printer is shown in Fig. 2-1.

Data (From Host Computer)

Print head

LED

Switch

Control panel board

Power supply unit

AC Power

Parallel interface

Masked ROM

UVE-PROM

512K

EE-PROM

Main logic board

Driver

Gate array

CPU

Driver

RAM

Carriage motor

Detectors

Paper feed motor

Printer mechanism

Fig. 2-1 Block Diagram

(1) Main Logic Board

This board receives data from the host computer and stores it in the RAM in the order it arrives. The CPU on this board reads the data from the RAM, and edits it according to the program stored in the ROM. When editing is completed, various drive signals from the CPU are sent to the printer mechanism to perform printing.

Explanation

• CPU TMP90C041 Controls this printer.

• UVE-PROM 27512 512K bit Contains the program which executes control of the printer. UVE-PROM is not provided with some versions of the software.

• Masked ROM 2M bit Contains the character font and the program.

• EE-PROM KM93C46 64 × 16 bits Contains the data (EDS data and so on) in the memory switch.

• RAM 256K bytes Used as a stack area, work area and data buffer of the CPU.

• Parallel interface

• Gate array (custom IC) Inputs/outputs several signals.

• Driver The data edited by the CPU and gate array are sent to the printer mechanism after conversion to the signal for the print head drive and motor drives.

(2) Control panel board

Panel circuit for manual control of the printer.

(3) Printer Mechanism

Consists of a print head, carriage motor, paper feed motor, and detectors.

(4) Power Supply Unit

Converts AC power to 33VDC and 5VDC.

– 19 –

2. Main Logic Board

2-1. General Flow Chart

The flow chart below shows you the general flow of editing and printing operations.

POWER ON

Initialization

Ready state

Read data

Control

code?

Control code

Data processing

Return action

YES

processing

Print?

YES

or printing

Return?

YES

Data

storage

(Line buffer determination)

(Print out of data)

Fig. 2-2 General Flow Chart of Editing and Printing

– 20 –

3. Power Supply Circuit

A ringing choke converter type circuit is used with a dropper type circuit in the power supply unit, fulfilling the input and output conditions described in the chart below.

Voltage Range Max. Current Output Service Circuit Type

Input

Output

110VAC, 120VAC 1.0 A

220VAC to 240VAC 0.6 A

5 VDC ±5% 0.4 A Dropper

For logic circuit drive, for motor holding.

33 VDC ±5% 1.25A Ringing choke

For print head drive, for motor

converter.

drive.

Input

110VAC 120VAC 220VAC 230VAC 240VAC   

Noise filter circuit

Switching section (Transistor Q1)

Control circuit

In rush current protection circuit

Transformer T1

PC1

Photo-Coupler

Fig. 2-3 Power Supply unit block diagram

Rectifier circuit

Ringing choke converter

Dropper circuit

Voltage reference

Output 33V DC

Output 5V DC

– 21 –

4. Mechanism

4-1. Print Head Mechanism

The print head consists of 9 needle wires and 9 print solenoids. The following explains how each needle wire operates during printing. (1) When the print solenoid is energized, the clapper is attracted by the iron core and the needle wire is driven toward

the platen. (2) This needle wire hits the platen via the ink ribbon and paper. A single dot is printed on the paper. (3) When the print solenoid is de-energized, the needle wire is returned to its original position by rebound energy and

spring and clapper holder (leaf spring) force.

Paper

Platen

Spring

Paper guide

Ink ribbon

Clapper holder

Stopper

Clapper

Needle wire

Print solenoid

Guide

Subguide

Iron core

Fig. 2-4 Outline of Print Head Mechanism

– 22 –

4-2. Print Head Carrying Mechanism

The print head carrying mechanism consists of a carriage, timing belt, carriage motor, and home position detector.

Carriage

The carriage is supported horizontally by the carriage stay and rear angle. The carriage moves from side to side with

the print head mounted above it. A timing belt is clamped to the base of the carriage and a shield plate is mounted

at the base for home position detection.

Timing Belt

The timing belt is suspended between the timing pulley of the carriage motor and the timing pulley of the tension

lever. The timing belt maintains a constant tension.

The timing belt is also clamped to the base of the carriage so that it can move the carriage accurately with driving

force from the carriage motor.

Carriage Motor

The carriage motor is a HB (Hybrid)type, 4-phase, 192-pole pulse motor driven by pulse signals from the control

circuit. The rotational rate depends on the number of pulses per unit time. By varying this rotational rate (carriage

carrying rate), the size of the horizontal letters can be changed in each print mode.

Fig. 2-5 Print Head Carrying Mechanism

– 23 –

4-3. Ink ribbon feed mechanism

The ink ribbon feed mechanism is linked to the print head carrying mechanism so the ink ribbon always winds automatically in the same direction while the carriage moves left and right. The movement of the carriage along the serrated edge of the rear angle of the printer mechanism drives the idler gear. The rotation of the idler gear is conveyed sequentially to the gears that work and wind the ribbon. The carriage has a clutch lever that keeps the direction of the cassette gear rotation constant, regardless of the direction of the idler gear rotation as the carriage moves left and right.

Cassette Gear

Gear of The Clutch Lever

Idler Gear

Fig. 2-6 Ribbon feed mechanism

– 24 –

4-4. Paper Feed Mechanism

The paper feed mechanism consists of a paper feed motor, an idler gear, a platen and a traction unit. The paper feed motor is a PM (Permanent Magnet) 4-phase and 48 pulse motor. There are two ways of feeding paper into the printer: the friction method and the tractor method. You can select the method you want to use by setting the release lever on the optional push tractor unit.

Position of release lever [1] [2]

Engaement of the PF idler gear Not linked Linked Status of the PF roller and

PF roller Release lever position detector Open Closed

Paper feeding method Friction Tractor

• Friction Method

Friction method is selected when the release lever is position [1].

With this method, paper is pressed between the platen roller and the holder roller therefore, paper is fed as the rollers

turn.

As the paper feed motor is driven, the motor gear, through the idler gear, turns the platen gear in the paper feeding

direction. However, since the tractor gear and the tractor clutch are not linked at this time, the tractor unit will not

be driven.

• Tractor Method

Tractor method is selected when the release lever is position [2].

Paper feeding is facilitated by rotation of the sprocket pin of the tractor unit. When the tractor method is selected,

the PF idler gear is linked to the PF idler gear, enabling the drive force generated by the paper feed motor to be

transferred to the tractor unit via the idler gear.

Pressed Not

Fig. 2-7 Paper Feed Mechanism

– 25 –

4-5. Detectors

(1) Print head temperature detectors

The A/D converter in the CPU detects the print head temperature at power on and before each line begins to print.

+5V +5V

Printer head

ref

Thermistor

AN0

CPU

R2

Fig. 2-8 Printer head temperature detector circuit

Control Method

A/D Conversion Value

POINT

AN Voltage

Temperature

°C

Error stop (thermistor open) 0-5 0.00 Normal print 6-213 0.00-4.35 ~120 Unidirectional print 214-221 4.35-4.48 120-130 Print stop 222-251 4.48-4.83 Over 130 Error stop (thermistor closed) 252-255 Over 5.00 -

(2) Home Position Detector

A photo-interrupter is used in the home detector on the printer.

ON/OFF signals are generated according to the position of the carriage. (Shield plate mounted at the base of the

carriage.) The printing position is determined by these signals.

Detecting

signal

+5V

Fig. 2-9 Carriage home position detector circuit

Control Method

Output (V) Decision

5 in home position (with shield plate) 0 not in home position (without shield plate)

– 26 –

+5V

+ 78 hidden pages