Document Outline
- LTPH245
- COPYRIGH.pdf
- PREFACE.pdf
- CHAP1.pdf
- CHAP3.pdf
- CHAP4.pdf
- CHAP5.pdf
- CHAP6.pdf
- CHAP8.pdf
LTPH245
LINE THERMAL PRINTER MECHANISM
TECHNICAL REFERENCE
U00027926850
Seiko Instruments Inc.
LTPH245 TECHNICAL REFERENCE
Document Number U00027926850
First Edition
December 1999
Copyright 1999 by Seiko Instruments Inc.
All rights reserved.
Seiko Instruments Inc. (SII) has prepared this manual for use by SII personnel, licensees, and customers.
The information contained herein is the property of SII and shall not be reproduced in whole or in part
without the prior written approval of SII.
SII reserves the right to make changes without notice to the specifications and materials contained herein
and shall not be responsible for any damages (including consequential) caused by reliance on the
materials presented, including but not limited to typographical, arithmetic, or listing errors.
SII is a trademark of Seiko Instruments Inc.
iii
PREFACE
This reference manual describes the specifications and basic operating procedures for the LTPH245 Line
Thermal Printer Mechanism (hereinafter referred to as "printer").
Chapter 1 "Precautions" describes safety, design and operational precautions. Read it thoroughly before
designing so that you are able to use the printer properly.
SII has not investigated the intellectual property rights of the sample circuits included in this manual. Fully
investigate the intellectual property rights of these circuits before using.
iv
TABLE OF CONTENTS
Section
Page
CHAPTER 1 PRECAUTIONS
1.1
SAFETY PRECAUTIONS .............................................................................................
1-1
1.2
DESIGN AND HANDLING PRECAUTIONS.................................................................
1-2
1.2.1
Design Precautions..........................................................................................
1-2
1.2.2
Handling Precautions.......................................................................................
1-4
CHAPTER 2 FEATURES
CHAPTER 3 SPECIFICATIONS
3.1
GENERAL SPECIFICATIONS......................................................................................
3-1
3.2
HEAT ELEMENT DIMENSIONS...................................................................................
3-3
3.3
PAPER FEED CHARACTERISTICS ............................................................................
3-4
3.4
STEP MOTOR CHARACTERISTICS ...........................................................................
3-5
3.4.1
Motor Drive Circuit ...........................................................................................
3-6
3.4.2
Motor Timing....................................................................................................
3-8
3.4.3
Precautions for Driving the Motor ....................................................................
3-10
3.5
THERMAL HEAD..........................................................................................................
3-12
3.5.1
Structure of the Thermal Head ........................................................................
3-12
3.5.2
Printed Position of the Data .............................................................................
3-14
3.5.3
Head Resistance..............................................................................................
3-15
3.5.4
Head Voltage ...................................................................................................
3-16
3.5.5
Peak Current....................................................................................................
3-16
3.5.6
Thermal Head Electrical Characteristics..........................................................
3-17
3.5.7
Timing Chart ....................................................................................................
3-18
3.6
CONTROLLING THE HEAD ACTIVATION (DST) PULSE WIDTH .............................
3-19
3.6.1
Calculation of Head Activation Pulse Width.....................................................
3-19
3.6.2
Calculation of Applied Energy..........................................................................
3-19
3.6.3
Calculation of Head Activation Voltage............................................................
3-20
3.6.4
Calculation of Head Resistance.......................................................................
3-20
3.6.5
Determination of Activation Pause Time and Activation Pulse Period.............
3-21
3.6.6
Head Activation Pulse Term Coefficient ..........................................................
3-21
3.6.7
Head Storage Coefficient.................................................................................
3-22
3.6.8
Calculation Sample for the Head Activation Pulse Width ................................
3-23
3.6.9
Thermistor Resistance.....................................................................................
3-24
3.6.10 Detecting Abnormal Temperatures of the Thermal Head................................
3-26
3.7
PAPER DETECTOR .....................................................................................................
3-27
3.7.1
General Specifications .....................................................................................
3-27
3.7.2
Sample External Circuit ...................................................................................
3-28
v
Section
Page
3.8
PLATEN POSITION SENSOR......................................................................................
3-29
3.8.1
General Specification.......................................................................................
3-29
3.8.2
Sample External Circuit ..................................................................................
3-29
CHAPTER 4 CONNECTING EXTERNAL CIRCUITS
4.1
THERMAL HEAD CONTROL TERMINALS .................................................................
4-1
4.2
MOTOR AND DETECTOR TERMINALS .....................................................................
4-3
4.3
CAUTION IN CONNECTION........................................................................................
4-4
CHAPTER 5 DRIVE METHOD
5.1
THERMAL HEAD DRIVE TIMING ................................................................................
5-1
5.2
MOTOR DRIVE TIMING ...............................................................................................
5-2
CHAPTER 6 HOUSING DESIGN GUIDE
6.1
SECURING THE PRINTER ..........................................................................................
6-1
6.1.1
Printer Mounting Method..................................................................................
6-1
6.1.2
Mounting Platen Block .....................................................................................
6-2
6.1.3
Precautions for Securing the Printer ................................................................
6-3
6.2
LAYOUT OF PRINTER AND PAPER ...........................................................................
6-4
6.3
WHERE TO MOUNT THE PAPER HOLDER...............................................................
6-4
6.4
SETTING THE PAPER .................................................................................................
6-4
6.5
POSITIONING THE PAPER CUTTER .........................................................................
6-5
6.6
OUTER CASE STRUCTURE .......................................................................................
6-6
CHAPTER 7 APPEARANCE AND DIMENSIONS
CHAPTER 8 LOADING/UNLOADING PAPER AND HEAD CLEANING
8.1
LOADING/UNLOADING PAPER PRECAUTIONS .......................................................
8-1
8.2
HEAD CLEANING PROCEDURE AND PRECAUTIONS .............................................
8-3
8.2.1
PRECAUTIONS ...............................................................................................
8-3
8.2.2
PROCEDURE ..................................................................................................
8-3
vi
FIGURES
Figure
Page
3-1
Heat Element Dimensions ............................................................................................
3-3
3-2
Print Area ......................................................................................................................
3-3
3-3
Sample Drive Circuit .....................................................................................................
3-6
3-4
Input Voltage Signals for the Sample Drive Circuit .......................................................
3-7
3-5
Motor Start/Stop Timing ................................................................................................
3-8
3-6
Motor Drive Timing Chart..............................................................................................
3-10
3-7
Thermal Head Block Diagram.......................................................................................
3-13
3-8
Printed Position of the Data ..........................................................................................
3-14
3-9
Head Resistance Rank Sample....................................................................................
3-15
3-10
Timing Chart .................................................................................................................
3-18
3-11
Thermistor Resistance vs. Temperature.......................................................................
3-24
3-12
Sample External Circuit of the Paper Detector .............................................................
3-28
3-13
Sample External Circuit of the Platen Position Sensor .................................................
3-29
4-1
Thermal Head Control Terminals..................................................................................
4-1
4-2
Motor and Detector Terminals ......................................................................................
4-3
5-1
Example of Timing Chart of the Thermal Head Driving ................................................
5-1
5-2
Example of Motor Drive Timing Chart...........................................................................
5-3
6-1
How to secure the printer..............................................................................................
6-1
6-2
How to secure the Platen Block ....................................................................................
6-2
6-3
Paper Path ....................................................................................................................
6-4
6-4
Paper Cutter Mounting Position ....................................................................................
6-5
6-5
The Blade of the Paper Cutter ......................................................................................
6-5
6-6
Sample Outer Case Structure.......................................................................................
6-6
7-1
Appearance and Dimensions........................................................................................
7-2
7-2
Printer Main Body Appearance and Dimensions ..........................................................
7-3
7-3
Platen Block Appearance and Dimensions...................................................................
7-4
8-1
Loading Paper (1) .........................................................................................................
8-1
8-2
Loading Paper (2) .........................................................................................................
8-2
8-3
Head Cleaning Procedure.............................................................................................
8-3
vii
TABLES
Table
Page
3-1
General Specifications ..................................................................................................
3-1
3-2
Sample Motor Drive Frequency ....................................................................................
3-4
3-3
General Specifications of the Motor..............................................................................
3-5
3-4
Excitation Sequence .....................................................................................................
3-7
3-5
Acceleration Steps ........................................................................................................
3-11
3-6
Blocks and Activated Heat Elements ............................................................................
3-14
3-7
Head Resistance Ranks ...............................................................................................
3-15
3-8
Head Voltage ................................................................................................................
3-16
3-9
Thermal Head Electrical Characteristics.......................................................................
3-17
3-10
Activation Pulse Width ..................................................................................................
3-23
3-11
Temperature and Thermistor Resistance .....................................................................
3-25
3-12
Absolute Maximum Ratings of Detectors......................................................................
3-27
3-13
Detectors Input/Output Conditions................................................................................
3-28
4-1
Recommended Connectors ..........................................................................................
4-1
4-2
Thermal Head Control Terminal Assignments..............................................................
4-2
4-3
Motor and Detector Terminals Assignments.................................................................
4-3
1-1
1
PRECAUTIONS
Read through this manual to design and operate the printer properly.
Pay special attention to the precautions noted in each section.
1.1 SAFETY
PRECAUTIONS
Follow these precautions when designing a product using the printer, and include any necessary
precautions and warning labels to ensure the safe operation of your product by users.
Preventing the thermal head from overheating
When electricity is continuously supplied to the thermal head heat element by a CPU or other
malfunction, the thermal head may overheat, causing smoke and fire.
Follow the method described in Section 3.6.10 to monitor the temperature of the thermal
head to prevent overheating.
Turn the printer off immediately if any abnormal conditions occur.
Preventing the user from touching the thermal head and motor
Warn the user not to touch the thermal head, its periphery or motor as they are hot during and
immediately after printing. Failure to follow this instruction may lead to personal injury
including burns.
Also, allow cooling by designing clearance between the head, motor and the outer case.
Preventing the user from touching the rotary drive portion
Design the product so that the motor does not operate when the outer case and platen block
are open. The user could be caught in the motor when the drive gear is exposed.
CHAPTER
1-2
1.2 DESIGN AND HANDLING PRECAUTIONS
To maintain the initial level of performance of the printer and to prevent future problems from occurring,
observe the following precautions.
1.2.1 Design
Precautions
If too much energy is applied to the thermal head, it may overheat and become damaged.
Always use the printer with the specified amount of energy.
Do not apply a pulse of 2V and 20 nsec or higher to each signal terminal of the thermal head.
Use C-MOS IC chips (74HC240 or equivalent) for interfacing the CLK, LATCH, DAT and DST
signals of the thermal head.
When turning the power on or off, always DISABLE (put in "Low" state) the DST terminals.
To prevent the thermal head from being damaged by static electricity:
Fix the printer to the Frame Ground (FG) with the FG connector as shown in Figure 7-2.
Connect the GND terminal (SG) to FG through 1 M
resistor so that the electric potential
of the SG of the thermal head and the FG of the printer are equal.
Keep the Vp power off when not printing to prevent the thermal head from becoming
electrically corroded.
Wire resistance should be 50 m
or less (however the less the better) between the power
supply and the Vp, and the GND terminals on the thermal head controller. Maintain a
considerable distance from signal lines to reduce electrical interference.
The surge voltage between Vp and GND should not exceed 10 V.
As a noise countermeasure, connect the capacitor noted below between the Vdd and GND
terminals near the thermal head control connector.
Vp
GND:
approximately 10
F
Vdd
GND:
approximately 1
F
When turning the power on or off, perform the Vp and Vcc simultaneously or in the order of 1)
and 2) as follows:
At power ON:
1) Vcc (5 V)
2) Vp
At power OFF:
1) Vp
2) Vcc (5 V)
Always monitor the output of the platen position sensor and paper detector. Incorrect
activation of the thermal head may damage and reduce the longevity of the thermal head and
the platen.
Design the outer case so that the paper detector is not affected by light from outside. Since a
reflection type photo interrupter is used in the paper detector, the detector may be affected by
light from outside.
1-3
Allow for movement of the FFC when designing the outer case because the FFC will shift 1 to
2 mm from the thermal head moving. Also, design the outer case so that it prevents the
paper feed out from being caught in the platen.
For the position in which the
platen block should be fixed,
and the way it is mounted,
follow the instructions shown
in Figure 7-1.
Since the printer mechanism
does not have the function to
prevent paper from sliding,
design the outer case so that
the paper is guarded securely.
Design so that the
paper feed load is
0.49N (50 gf) or
less.
As to the center of the rotation of the
cover of the platen block that is
mounted, follow the instructions
shown in Figure 7-1
.
The lever should be used when removing and
installing the platen block. It should never be
pulled by force.
1-4
1.2.2 Handling
Precautions
To maintain the initial level of performance of the printer and to prevent future problems from occurring,
observe the following precautions.
Also, include any necessary precautions to ensure the safe operation of your product by users.
To protect the heat elements, ICs, etc. from static electricity, discharge all static electricity
before handling the printer.
Pay special attention to the thermal head control terminals when handling.
Do not apply stress to the thermal head control terminals: Doing so may damage the
connectors and FFC (Flexible Flat Cable).
Using anything other than the specified paper may cause the following:
Poor printing quality
Abrasion of the thermal head
The thermal surface of the paper and the thermal head may stick together
Excessive
noise
Fading
print
Corroded thermal head
Always print or feed with the specified paper inserted to protect the platen, thermal head, and
reduction gear.
Do not hit or scratch the surface of the thermal head with sharp or hard objects as it may
damage the heat element.
If the thermal head remains in contact with the platen, the platen may become deformed and
deteriorate print quality.
If the platen is deformed, the uneven surface of the platen can be recovered by feeding paper
for a while.
Never connect or disconnect cables with the power on. Always power off the printer first.
When printing a black or checkered pattern at a high print rate in a low temperature or high
humidity environment, the vapor from the paper during printing may cause condensation to
form on the printer or may soil the paper.
If water condenses on the printer, keep the thermal head away from water drops as it may
corrode the thermal head, and turn printer power off until it dries.
Prevent contact with water and do not operate with wet hands as it may damage the printer or
cause a short circuit or fire.
Never use the printer in a dusty place, as it may damage the thermal head and paper feeder.
2-1
2
FEATURES
The LTPH245 Line Thermal Printer Mechanism is a compact, high-speed thermal line dot printing
mechanism. It can be used with a measuring instrument and analyzer, a POS, a communication device,
or a data terminal device. Since the printer can be battery driven, it can easily be mounted onto a
portable device such as a hand-held terminal.
The LTPH245 has the following features:
Battery drive
Since the range of operating voltage of 4.2V to 8.5V is wide, four to six Ni-Cd batteries or Ni-
MH batteries or two Lithium-ion batteries can also be used.
Compact and light weight
1
The mechanism is compact and light: 76.8 mm in width, 38 mm in depth, 16 mm in height,
and approximately 46 g in weight.
Improved operability
The platen roller can be released easily by lever operation allowing easy paper installation and
head cleaning.
High resolution printing
A high-density print head of 8 dots/mm produces clear and precise printing.
Longevity
The mechanism is maintenance-free with a long life of 50 km print length and/or 100 million
pulses.
High speed printing
2
A maximum print speed of 200 dot lines per second (25 mm per second) at 5 V, 450 dot lines
per second (56.25 mm per second) at 7.2 V, and 500 dot lines per second (62.5 mm per
second) at 8.0 V are attainable.
Low current consumption
The printer can be driven on low discharge current lithium-ion batteries due to low current
consumption. Continuous printing can be also performed.
CHAPTER
2-2
Low noise
Thermal line dot printing is used to guarantee low-noise printing.
Realizing easy design of outer case
The printer mechanism is designed to fit easily into the outer case, allowing for
reduced number of outer case parts.
1
The external dimensions exclude those of the lever and platen frame. 46 g in weight
includes all parts.
2
Print speed differs depending on working and environmental conditions.
3-1
3
SPECIFICATIONS
3.1 GENERAL
SPECIFICATIONS
Table 3-1 General Specifications
Item
Specification
Print method
Thermal dot line printing
Dots per line
384 dots
Resolution
8 dots/mm
Print width
48 mm
Maximum printing speed
200 dot lines/s (25.0 mm/s) (at 5 V)
1
450 dot lines/s (56.25 mm/s) (at 7.2 V)
1
500 dot lines/s (62.5 mm/s) (at 8.0 V)
1
Paper feed pitch
0.125 mm
Head temperature detection
Via thermistor
Platen position detection
Via mechanical switch
Out-of-paper detection
Via photo interrupter
Operating voltage range
V
P
line (for head and motor drive)
V
dd
line (for head logic)
4.2 V to 8.5 V
7
(equivalent to four through six Ni-Cd or Ni-MH
batteries, or two lithium-ion batteries)
4.5 V to 5.5 V
Current consumption
For driving the head (V
P
)
For driving the motor (V
P
)
For head logic (V
dd
)
Average:
1.8 A (at 5 V), 2.6 A (at 7.2 V), 2.8 A (at 8.0 V)
2
Maximum:
2.1 A (at 5 V), 3.0 A (at 7.2 V), 3.3 A (at 8.0 V)
2
Maximum 0.46 A
Maximum 0.01 A
1
Maximum printing speed is attained with the following conditions:
When the driving voltage is 5 V, the character size is a 24-dot font, the line spacing is 16 dots, the temperature of
the head is 60
C or more, and the number of simultaneously activated dots is 64 dots or less
When the driving voltage is 7.2 V, the temperature of the head is 40
C or more, and the number of simultaneously
activated dots is 64 dots or less
When the driving voltage is 8.0 V, the temperature of the head is 30
C or more, and the number of simultaneously
activated dots is 64 dots or less.
2
When the number of simultaneously activated dots is specified as 64.
CHAPTER
3-2
Table 3-1 General Specifications (Continued)
Item
Specification
Operating temperature range
-5
C to 50
C
3
No condensation
Storage temperature range
-25
C to 70
C
3
No condensation
Life span (at 25
C and rated energy)
Activation pulse resistance
Abrasion resistance
100 million pulses or more (print ratio=12.5%)
50 km or more
Paper width
58 mm
Paper feeding force
0.49N (50 gf) or more
Paper holding force
0.78N (80 gf) or more
Dimensions (width
depth
height)
76.8
38.0
16.0 mm (excluding lever)
Weight
Approximately 46 g
Recommended thermal paper
TF50KS-E2C
(65
m paper)
TP50KJ-R
(65
m paper)
AP50KS-E
(65
m paper)
from Nippon Paper Industries
HP220-AB1
(65
m paper)
from Mitsubishi Paper Industries
PD160R-N (75
m paper)
4
from Oji Paper Industries
3
Outside this range, prining may blot or be light.
4
When
the print
ratio is high, this thermal paper may generate a noise during printing.
5
The paper roll should be placed facing the thermal surface outward (See Figure 6-3). Also, do not use paper with
edges that are pasted or have turnups at the start of the roll. If they need to be used unavoidably, replace with new
paper roll as soon as possible before the entire roll is used up.
+0
- 1
3-3
3.2 HEAT ELEMENT DIMENSIONS
The printer contains a thermal head with 384 heat elements (dot-size).
Figure 3-1 Heat Element Dimensions
Figure 3-2 Print Area
48 mm (384 DOTS)
0.125 mm
0.125 mm
58 mm (PAPER WIDTH)
48 mm (PRINTING WIDTH)
5 mm
0.125 mm
(PAPER
FEED
PITCH)
5 mm
+0
-1
3-4
3.3 PAPER FEED CHARACTERISTICS
Paper is fed in a forward direction when the motor shaft is rotating in the normal direction
(clockwise) when seen from the motor gear side.
The motor is driven by a 2-2 phase excitation, constant current chopper method and feeds
paper 0.125 mm (equivalent to a single dot pitch) every two steps of the motor drive signal.
To prevent deterioration in printing quality due to backlash of the paper feed system, the motor
should be driven 40 steps in a reverse direction and then 40 steps in the normal direction during
initialization or after backward feeding.
During paper feeding, the motor should be driven lower than the value obtained by equation (1).
Equation (1):
Vp
165 - 220 (pps) (max.1000 (pps) )
During printing, the motor drive frequency should be adjusted according to working conditions
such as voltage, temperature, number of activated dots, etc. (For details, see CHAPTER 5
DRIVE METHOD.)
Do not print while the motor is rotating in the reverse direction.
Table 3-2 Sample Motor Drive Frequency
Operating Voltage
Drive Frequency
(Paper feed)
4.2 V
473 pps
5 V
605 pps
6 V
770 pps
7.2 V
968 pps
8 V
1000 pps
8.5 V
1000 pps
3-5
3.4 STEP MOTOR CHARACTERISTICS
Table 3-3 General Specifications of the Motor
Item
Specification
Type
PM
Number of phases
4-phase
Drive method
Bipolar chopper
Excitation
2-2 phase
Winding resistance per phase
14
10%
Rated voltage
4.2 - 8.5 V
Rated current
0.23 A/phase, 0.15A/phase
1
Maximum current consumption
0.46 A
Drive frequency
50 - 1000 pps (according to drive voltage)
1
See 3.4.3 Precautions for Driving the Motor.
3-6
3.4.1 Motor Drive Circuit
(1) Sample Drive Circuit
Sample drive circuits for the motor are shown in Figure 3-3.
19
4
5
3.3K
1%
2.7K
1%
0.1
F
PC1060
2
3
0.1
F
1
9
1
11
20
14
13
8
11
3
16
4
2
13
17
14
13
20
11
1
9
4
1
3
2
15
6
1
15
14
7
6
10
12
12
2
3
18
19
6
15
4
5
0.51
1%
1/2W
0.51
1%
1/2W
10
F
50V
10
F
50V
1K
1%
1K
1%
3K
1%
3K
1%
10K
10K
74HC32
74HC32
NC
NC
0.1
F
PH1
Vcc
Vcc
Vcc
Vcc
Vcc
Vcc
Vp
Vp
B
A
B
A
0.01
F
10%,10%
1.8K
1%
1SS294
PH2
PH3
PH4
CTCRL
0.01
F
10%,10%
0.01
F
10%,10%
0.01
F
10%,10%
18
3
2
LB1843V
LB1843V
74HC123A
5
17
9
12
Figure 3-3 Sample Drive Circuit
3-7
(2) Excitation Sequence
As shown in Table 3-4, the printer feeds paper in the normal direction when the motor is excited
in the order of step 1, step 2, step 3, step 4, step 1, step 2, . . . . On the other hand, to rotate the
motor in a reverse direction, drive the motor in the reverse order of: step 4, step 3, step 2, step
1, step 4, step 3, . . . .
Table 3-4 Excitation Sequence
Signal Name
Sequence
Step 1
Step 2
Step 3
Step 4
A
Low
High
High
Low
B
High
High
Low
Low
A
High
Low
Low
High
B
Low
Low
High
High
Figure 3-4 Input Voltage Signals for the Sample Drive Circuit
H
L
H
L
H
L
H
L
A
B
A
B
1 DOT LINE
3-8
3.4.2 Motor
Timing
Refer to the timing chart in Figure 3-5 when designing the control circuit and/or software for starting and
stopping the motor. Also take note of the following precautions:
Precautions for Designing the Motor Control Circuit and Software
(1) Stop step
To stop the motor, excite for a single step period with a phase that is the same as the final one
in the printing step.
(2) Pause state
In the pause state, do not excite the step motor to prevent the motor from overheating. Even
when the step motor is not excited, it maintains a holding force to prevent paper from sliding.
(3) Start step
To restart the motor from the stop step, shift the motor into the printing sequence.
To restart the motor from the pause (no excitation) state, shift the motor into the printing
sequence after outputting a single step of a phase that is the same as that of the stop step.
Figure 3-5
Motor Start/Stop Timing
STOP
STEP
PH2
PH1
PRINT STEP
PRINT STEP
H
L
L
H
H
L
L
H
PAUSE
STATE
START
STEP
PH3
PH4
1 DOT LINE
3-9
(4) Others
Do not print paper in intermittent feed mode. Doing so may deteriorate the printing quality due
to irregular paper feeding pitch.
To print characters and bit images, always follow the start step and stop step.
3-10
3.4.3 Precautions for Driving the Motor
(1) Motor Current Control
When the motor speed decreases during printing because of the division drive method, the contents of
print data, or input data transfer speed, noise and overheating of the motor may occur due to over-
torque of the motor.
To prevent these symptoms from occurring, control the motor current as follows:
First, activate the motor with the 1st setting current in each motor drive step.
Change the activation current to the 2nd setting current after activating the motor with the 1st setting
current for T1.
T1 is defined from each period of the motor drive step and Vp voltage as follows:
How to define T1 (unit:
s)
When Vp is under 7.2 V :
T1: Compare the following two values and adopt the smaller one.
(Each period of the motor drive step - 500) and 925.9
When Vp is 7.2 V or more :
T1: Compare the following two values and adopt the smaller one.
(Each period of the motor drive step - 500) and (1000000 / (3600 - Vp
350))
CTCRL
T1
T1
T1
T1
T1
PH1
PH2
PH3
PH4
Start
1st step
2nd step
3rd step
4th step
230mA
150mA
(6.58ms)
(6.58ms)
(4.07ms)
(3.14ms)
(2.64ms)
Set the 1st setting current at CTCRL="High":
0.23 (A)
Set the 2nd setting current at CTCRL="Low":
0.15 (A)
Figure 3-6 Motor Drive Timing Chart
3-11
(2) Acceleration Control
When driving the motor, acceleration control is needed to start paper feeding. When the motor is to be
driven at the maximum motor drive frequency that is calculated using equation (1), the motor may come
out of step under heavy load.
Drive the motor to the maximum driving speed that is calculated using equation (1), according to the
acceleration steps in Table 3-5.
The method for accelerating the motor is as follows;
1. Output start step (6580 (
s)) for the time calculated using equation (1)
2. Output first step for the first acceleration step time
3. Output second step for the second acceleration step time
4. Output nth step for the nth step acceleration time
5. After outputting the time calculated using equation (1), the motor is driven at a constant speed.
The printer can print during acceleration.
Table 3-5 Acceleration Steps
Number of
Steps
Speed
(pps)
Step Time
(
s)
start
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
152
246
318
379
433
493
547
597
644
687
728
768
805
840
874
907
939
970
1000
6580
6580
4066
3140
2636
2311
2028
1828
1675
1553
1456
1374
1302
1242
1191
1144
1103
1065
1031
1000
3-12
3.5 THERMAL
HEAD
3.5.1 Structure of the Thermal Head
As shown in Figure 3-7, the thermal head of the printer consists of 384 heat elements, and head drivers
to drive the heat elements.
Serial printing data input from the DAT terminal is transferred to the shift register synchronously with the
CLK signal, then stored in the latch register with the timing of the LATCH signal.
Inputting the head activation signal (DST 1 to 6) activates heat elements in accordance with the printing
data stored in the latch register.
A maximum of six division printing is available for the printer.
Table 3-7 shows the relationship between DST signals and heat elements.
3-13
DAT
CLK
LATCH
DST6
DST5
DST2
DST1
TH
Vdd
GND
Vp
Shift Register
Latch Register
Output Driver
Heat Element
D
O
T
384
D
O
T
321
D
O
T
320
D
O
T
257
D
O
T
256
D
O
T
129
D
O
T
128
DO
T
6
5
DO
T
6
4
DO
T
1
Block6
Block5
Blcok2
Block1
Thermistor
Figure 3-7 Thermal Head Block Diagram
3-14
Table 3-6 Blocks and Activated Heat Elements
Block Number
Heat Element Number
Dots / DST
1
1 - 64
64
2
65 - 128
64
3
129 - 192
64
4
193 - 256
64
5
257 - 320
64
6
321 - 384
64
3.5.2 Printed Position of the Data
Data dots from 1 to 384 which are transferred through DAT are printed as shown in Figure 3-8.
Figure 3-8
Printed Position of the Data
LTPH245 PRINTER MECHANISM
1 2 3 4 5 6 ............................ 382 383 384
PAPER FEED DIRECTION
PRINT SURFACE
DATA PRINT SEQUENCE
PAPER
DATA INPUT SEQUENCE 1 2 3 4 5 6 . . . . . . 382 383 384
DATA IN
3-15
3.5.3 Head
Resistance
The head resistance of the printer is classified into three ranks as shown in Table 3-7.
Table 3-7 Head Resistance Ranks
Rank
Head Resistance
A
178.6 to 195.5
B
161.6 to 178.5
C
144.5 to 161.5
* The head resistance ranks are indicated on the label located on the top of the printer.
Sample Label showing the Head Resistance Rank
In this example, the head resistance rank is B.
Figure 3-9 Head Resistance Rank Sample
3-16
3.5.4 Head
Voltage
The printer has a built-in head driver IC. Table 3-8 shows the head voltage.
Table 3-8 Head Voltage
Item
Voltage Range
Head drive voltage
Vp
4.2 to 8.5 V
Head logic voltage
Vdd
4.5 to 5.5 V
3.5.5 Peak
Current
Since the peak current (maximum current) may reach the values calculated using equation (2) when the
thermal head is driven, make sure that the allowable current for the cable material and the voltage drop
on the cables are well within the specified range.
Equation (2):
Ip:
Peak current (A)
N:
Number of dots that are driven simultaneously
Vp:
Head drive voltage (V)
RH:
Head resistance (
)
N
Vp
Ip=
RH
3-17
3.5.6 Thermal Head Electrical Characteristics
Table 3-9 Thermal Head Electrical Characteristics
(Vdd=4.5 to 5.5V, Ta=0 to 50
C)
Rated Values
Item
Simbol
Conditions
MIN
TYP
MAX
Unit
Head resistance
RH
144.5
170
195.5
Head drive voltage
Vp
4.2
7.2
8.5
V
Head drive current
Ip
max. common activated dot 64
1.3
2.6
3.5
A
Logic block voltage
Vdd
4.5
5.0
5.5
V
Waiting for activation
-
-
0.5
mA
fclk=4MHz,DAT=fixed
-
-
6
mA
Logic block current
Idd
Ta=
25
C
fclk=4MHz,DAT=1/2fclk
-
-
10
mA
"High" input voltage
Vih
CLK,DAT,LATCH,DST
0.8
Vdd
-
Vdd
V
"Low" input voltage
Vil
CLK,DAT,LATCH,DST
0
-
0.2
Vdd
V
CLK
-
-
3
A
DAT
-
-
0.5
A
LATCH
-
-
3
A
"High" input
current
DST
Iih
Ta=25
C
Vdd=5.0(V)
Vih=5.0(V)
-
-
55
A
CLK
-
-
-3
A
DAT
-
-
-0.5
A
LATCH
-
-
-3
A
"Low" input
current
DST
Iil
Ta=25
C
Vdd=5.0(V)
Vil=0(V)
-
-
-0.5
A
Driver leak current
I leak Vp=7(V), for 1 bit
-
-
1.0
A
CLK frequency
fclk
-
-
4
MHz
CLK pulse width
t1
See the Timing Chart
80
-
-
ns
DAT setup-time
t2
See the Timing Chart
50
-
-
ns
DAT hold time
t3
See the Timing Chart
50
-
-
ns
LATCH setup time
t4
See the Timing Chart
120
-
-
ns
LATCH pulse width
t5
See the Timing Chart
120
-
-
ns
LATCH hold time
t6
See the Timing Chart
120
-
-
ns
DST setup time
t7
See the Timing Chart
120
-
-
ns
3-18
3.5.7 Timing
Chart
Figure 3-10 Timing Chart
3-19
3.6 CONTROLLING THE HEAD ACTIVATION (DST) PULSE WIDTH
3.6.1 Calculation of Head Activation Pulse Width
Head activation pulse width is calculated using the following equation (3).
To execute high quality printing using the printer, the value that is calculated using the following equation
(3) must be adjusted according to the environment the printer is used in. Calculate each value used
according to the steps in Sections 3.6.2 to 3.6.7 and control them so that the pulse width with the t
value obtained by substituting each value into the equation (3) is applied.
Printing using too high of a voltage or too long of a pulse width may shorten the life of the thermal head.
Equation (3):
t :
Head pulse width (ms)
E : Standard applied energy (mj)
See Section 3.6.2.
V : Applied voltage (V)
See Section 3.6.3.
R : Head resistance (
)
See Section 3.6.4.
C : Head pulse term coefficient
See Section 3.6.6.
D : Heat storage coefficient
See Section 3.6.7.
3.6.2 Calculation of Applied Energy
Applied energy should be in accordance with the temperature of the thermal head and the environment
the printer is used in.
The thermal head has a built-in thermistor. Measure the temperature using thermistor resistance.
Standard applied energy is based on a temperature of 25
C. Calculate the printing energy using
equation (4) and the temperature coefficient.
Equation (4):
E= (0.260 - T
C
(T
X
- 25) )
T
X
: Detected temperature using the thermistor (
C)
1
T
C
: Temperature coefficient
0.003373
1 The thermistor resistance value at T
X
(
C). See Section 3.6.8.
E
R
t =
C
D
V
2
3-20
3.6.3
Calculation of Head Activation Voltage
Calculate the applied voltage using equation (5).
Equation (5):
V=Vp
0.98 - 1.26
Vp: Head activation voltage (V)
3.6.4 Calculation of Head Resistance
A drop in voltage occurs depending on the wiring resistance. Calculate the head resistance using
equation (6).
Equation (6):
RH: Head resistance depending on resistance ranks
rank A (178.6 - 195.5
):
195.5 (
)
rank B (161.6 - 178.5
):
178.5 (
)
rank C (144.5 - 161.5
):
161.5 (
)
25: Wiring resistance in the thermal head (
)
R
C
: Common terminal wiring resistance in the thermal head:
0.2 (
)
r
C
: Wiring resistance between V
P
and GND (
)
1
N:
Number of dots driven simultaneously
1
It indicates a series resistance of wire and relay switching circuits used between the FFC terminals and power
supply.
( RH + 25 + (R
C
+ r
C
)
N )
2
R=
RH
3-21
3.6.5 Determination of Activation Pause Time and Activation Pulse Period
Dot lines may be activated in succession to the same thermal dot in order to protect thermal head
elements. Determine the activation period (the time from the preceding activation start to the current
activation start) which conforms to equation (7) to reserve the pause time.
Equation (7):
W > t + 0.5(ms)
W : Activation period of 1-dot line (ms)
3.6.6 Head Activation Pulse Term Coefficient
Make adjustments using the head activation pulse term coefficient (equal motor drive frequency) as the
printing density changes by the printing speed.
According to equations (8), calculate compensation coefficient C of the heat pulse.
Equation (8):
C = 1 - 2.6/(5.0 + w)
w = 2000 / motor drive frequency
3-22
3.6.7 Heat Storage Coefficient
In high speed printing, a difference in temperature arises between the rise in temperature of the thermal
head due to head activation and the temperature detected by the thermistor. Therefore, the activation
pulse must be corrected by simulating a rise in the temperature of the thermal head.
No correction is needed when the print ratio is low. When correction is not needed, set "1" as the heat
storage coefficient.
The heat storage coefficient is calculated as follows:
1)
Prepare the heat storage software counters to simulate heat storage.
(a) Heat storage due to head activation
The heat storage counter counts up in each print period as follows.
T'=T+
T : Heat storage counter value
N : Number of the activated dots
(b) Radiation
The heat storage counter value is multiplied by the radiation coefficient in each 2 msec.
T'=T
K
K : Radiation coefficient 0.996
2)
Calculate the heat storage coefficient with the following equation (9).
Equation (9)
D=1-
31936
N
6
T
3-23
3.6.8 Calculation Sample for the Head Activation Pulse Width
Table 3-10 lists the calculation sample of the head activation pulse width that was calculated using
equation (3) and the values obtained using equations (4) to (8).
Table 3-10 Activation Pulse Width
Motor Drive Frequency (PPS)
Head Drive
Voltage (V)
Thermistor
Temperature
100
200
300
400
500
600
700
800
900
1000
0
9.91
10
8.94
20
7.97
30
7.00
4.2
40
6.03
50
5.06
4.67
60
4.09
3.77
70
3.12
2.87
2.70
80
2.14
1.98
1.86
1.77
0
6.10
10
5.51
20
4.91
4.53
30
4.31
3.98
5.0
40
3.71
3.42
3.22
50
3.11
2.87
2.70
60
2.52
2.32
2.18
2.08
2.00
70
1.92
1.77
1.66
1.58
1.52
1.47
80
1.32
1.22
1.15
1.09
1.05
1.01
0
3.79
3.50
3.29
10
3.42
3.15
2.96
20
3.05
2.81
2.64
30
2.68
2.47
2.32
2.21
6.0
40
2.30
2.13
2.00
1.90
1.83
50
1.93
1.78
1.68
1.60
1.53
1.48
60
1.56
1.44
1.35
1.29
1.24
1.20
1.17
70
1.19
1.10
1.03
0.98
0.94
0.91
0.89
80
0.82
0.76
0.71
0.68
0.65
0.63
0.61
0
2.41
2.22
2.09
1.99
1.91
10
2.17
2.00
1.88
1.79
1.72
1.67
20
1.94
1.79
1.68
1.60
1.54
1.49
30
1.70
1.57
1.47
1.40
1.35
1.31
1.27
1.24
7.2
40
1.46
1.35
1.27
1.21
1.16
1.12
1.09
1.07
1.05
50
1.23
1.13
1.07
1.01
0.97
0.94
0.92
0.90
0.88
60
0.99
0.92
0.86
0.82
0.79
0.76
0.74
0.72
0.71
70
0.76
0.70
0.66
0.62
0.60
0.58
0.56
0.55
0.54
80
0.52
0.48
0.45
0.43
0.41
0.40
0.39
0.38
0.37
0
1.87
1.72
1.62
1.54
1.48
1.43
1.39
10
1.68
1.55
1.46
1.39
1.34
1.29
1.26
1.23
1.20
20
1.50
1.39
1.30
1.24
1.19
1.15
1.12
1.10
1.07
30
1.32
1.22
1.14
1.09
1.05
1.01
0.98
0.96
0.94
0.93
8.0
40
1.14
1.05
0.99
0.94
0.90
0.87
0.85
0.83
0.81
0.80
50
0.95
0.88
0.83
0.79
0.76
0.73
0.71
0.69
0.68
0.67
60
0.77
0.71
0.67
0.64
0.61
0.59
0.57
0.56
0.55
0.54
70
0.59
0.54
0.51
0.48
0.47
0.45
0.44
0.43
0.42
0.41
80
0.40
0.37
0.35
0.33
0.32
0.31
0.30
0.29
0.29
0.28
0
1.62
1.49
1.40
1.34
1.28
1.24
1.21
1.18
10
1.46
1.35
1.27
1.21
1.16
1.12
1.09
1.06
1.04
20
1.30
1.20
1.13
1.07
1.03
1.00
0.97
0.95
0.93
0.91
30
1.14
1.05
0.99
0.94
0.91
0.88
0.85
0.83
0.82
0.80
8.5
40
0.98
0.91
0.85
0.81
0.78
0.76
0.73
0.72
0.70
0.69
50
0.83
0.76
0.72
0.68
0.66
0.63
0.62
0.60
0.59
0.58
60
0.67
0.62
0.58
0.55
0.53
0.51
0.50
0.49
0.48
0.47
70
0.51
0.47
0.44
0.42
0.40
0.39
0.38
0.37
0.36
0.36
80
0.35
0.32
0.30
0.29
0.28
0.27
0.26
0.26
0.25
0.25
Note)
The above table shows values for recommended 65
thermal paper, resistance rank B, Rc+rc=0.20, and N=64.
Do not use this area
because paper feed errors
may occur because of the
motor torque.
3-24
In the shaded area, the drive pulse width exceeds the allowable activation pulse width or the activation pulse width
exceeds the motor drive frequency. Therefore, use the motor drive frequency shown in the unshaded areas.
3-25
3.6.9 Thermistor
Resistance
The resistance of the thermistor at the operating temperature T
X
(
C) is determined using the following
equation (10).
Equation (10):
R
X
:
Resistance at operating temperature Tx (
C)
R
25
:
15 k
10% (25
C)
B:
3440 k
3%
T
X
:
Operating temperature (
C)
EXP (A): The Ath power of natural logarithm e (2.71828)
[Rating]
Operating temperature range: -40
C to +125
C
Figure 3-11 Thermistor Resistance vs. Temperature
1 1
R
X
=R
25
EXP B
-
273 + T
X
298
RESISTANCE
(k
)
1000
100
10
1
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
TEMPERATURE (
C)
3-26
Table 3-11 Temperature and Thermistor Resistance
Temperature
(
C)
Thermistor
Resistance (k
)
Temperature
(
C)
Thermistor
Resistance (k
)
-40
375.54
40
8.63
-35
275.40
45
7.26
-30
204.55
50
6.14
-25
153.76
55
5.22
-20
116.89
60
4.46
-15
89.82
65
3.83
-10
69.71
70
3.30
-5
54.61
75
2.86
0
43.17
80
2.48
5
34.42
85
2.17
10
27.66
90
1.90
15
22.40
95
1.67
20
18.27
100
1.47
25
15.00
30
12.40
35
10.31
3-27
3.6.10 Detecting Abnormal Temperatures of the Thermal Head
To protect the thermal head and to ensure personal safety, abnormal thermal head temperatures must
be detected by both hardware and software as follows:
Detecting abnormal temperatures by software
Design software that will deactivate the heat elements if the thermal head thermistor (TH)
detects a temperature 80
C or higher (thermistor resistance RTH
2.48 k
), and reactivate the
heat elements when a temperature of 60
C or lower (RTH
4.46 k
) is detected. If the thermal
head continues to be activated at a temperature higher than 80
C, the life of the thermal head
may be shortened significantly.
Detecting abnormal temperatures by hardware
If the control unit (CPU) malfunctions, the software for detecting abnormal temperatures may not
function properly, resulting in overheating of the thermal head. Overheating of the thermal head
may cause damage to the thermal head or injury.
Always use hardware in conjunction with software for detecting abnormal temperatures to
ensure personal safety. (If the control unit malfunctions, it may be impossible to prevent
damage to the thermal head even if a detection of abnormal temperature is detected by
hardware.)
Using a window comparator circuit or similar detector, design hardware that detects the
following abnormal conditions:
(a) Overheating of the thermal head (approximately 100
C or higher (RTH
1.47 k
)).
(b) Faulty thermistor connection (the thermistor may be open or short-circuited).
If (a) and (b) are detected, immediately deactivate the heat elements. Reactivate the heat
elements after the temperature of the thermal head has returned to normal.
3-28
3.7 PAPER
DETECTOR
The printer has a built-in paper detector (reflection type photo interruptor) to detect whether paper is
present or not.
An external circuit should be designed so that it detects output from the paper detector and does not
activate the thermal head and motor when there is no paper. Doing not so may cause damage to the
thermal head or platen roller or shorten the life of the head significantly. If the motor is drived when it is
out-of paper, a load is put on the reduction gear and the life of the gear may be shortened.
3.7.1 General
Specifications
Table 3-12 Absolute Maximum Ratings of Detectors
(at 25
C)
Item
Symbol
Rating
Forward current
I
F
50 mA
Reverse voltage
V
R
5 V
LED (input)
Allowable current
P
70 mW
Collector-to-emitter
voltage
V
CEO
20 V
Emitter-to-collector
voltage
V
ECO
5 V
Collector current
I
C
20 mA
Phototransistor
(output)
Collector loss
P
C
70 mW
Operating temperature
T
opr
-20
C to + 80
C
Storage temperature
T
stg
-30
C to + 100
C
3-29
Table 3-13 Detectors Input/Output Conditions
Item
Symbol
Conditions
Standard
Max.
Forward voltage
V
F
I
F
=10mA
1.2V
1.6V
LED
(input)
Reverse current
I
R
V
R
=5V
-
10
A
Photo-
transistor
(output)
Dark current
I
CEO
If=0mA, V
CE
=10V
-
200nA
Photo electric
current
I
C
I
F
=10mA, V
CE
=5V
-
350
A
Leak current
I
LEAK
I
F
=10mA, V
CE
=5V
-
1
A
Collector
saturation
voltage
V
CE
(sat)
I
F
=10mA, I
C
=50
A
-
0.5V
Response time
(at rise)
t
r
I
C
=1mA, V
CC
=5V
5
s
-
Transfer
characteristics
Response time
(at fall)
t
f
R
L
=100
5
s
-
3.7.2 Sample External Circuit
Figure 3-12 Sample External Circuit of the Paper Detector
PS
VPS
GND
Photo interruptor
CPU Port
V
dd
(5V)
V
dd
(5V)
47k
220
GND
LTPH245
* The PS signal is high when there is no paper.
470pF
74HC04
3-30
3.8 PLATEN POSITION SENSOR
The printer has a platen position sensor to detect whether or not the platen block is set.
The platen position sensor is a switch type sensor shown in Figure 3-13. The platen position sensor
switch is closed when the platen block is set and is open when the platen block is released.
Design the control circuit so that the motor is not driven and the thermal head is not activated when the
platen block is open by detecting output of the platen position sensor.
3.8.1 General
Specification
Maximum rating: DC30V, 0.5A
Connection resistance: 200 m
or less
3.8.2 Sample External Circuit
Figure 3-13 Sample External Circuit of the Platen Position Sensor
Note that there is a time lag between operation of the platen position sensor and
completion of pressurization to thermal head.
To prevent a malfunction due to chattering of the switch, be sure to use the capacitor
shown in Figure 3-13.
Switch
GND
CPU Port
V
dd
(5v)
R=100k
HS
GND
C=0.1
F
* When the platen block is open
LTPH245
4-1
4
CONNECTING EXTERNAL CIRCUITS
The printer has a FFC (Flexible Flat Cable) type connector and normal type connector (model
No.51021-0900) made by Molex Co., Ltd. to connect to the external circuits.
Use the recommended connectors listed in Table 4-1 to connect the printer firmly to the external
circuits.
Table 4-1 Recommended Connectors
No.
External Circuit
Functions
Number of
Pins
Recommended Connectors
(in the external circuit side)
1
Thermal head control
20
Molex Co., Ltd.
52044-2010 (horizontal type)
52045-2010 (vertical type)
5597-20APB (horizontal type)
5597-20CPB (vertical type)
2
Motor control,
Paper detector
Platen position detection
9
Molex Co., Ltd.
53047-0910 (vertical type)
53048-0910 (horizontal type)
51047-0910 (transmission type)
4.1 THERMAL HEAD CONTROL TERMINALS
Figure 4-1 shows the terminals configuration of the FFC thermal head control terminals.
20
1
Figure 4-1 Thermal Head Control Terminals
CHAPTER
4-2
Table 4-2 Thermal Head Control Terminal Assignments
Terminal
Number
Signal Name
Input/
Output
Function
1
Vp
Input
Thermal head drive voltage
2
Vp
Input
Thermal head drive voltage
3
GND
-
GND
4
GND
-
GND
5
GND
-
GND
6
DAT
Input
Print data input (serial input)
7
CLK
Input
Synchronizing signal for print data transfer
8
LATCH
Input
Print data latch (memory storage)
9
DST6
Input
Thermal head print activation instruction signal
10
DST5
Input
Thermal head print activation instruction signal
11
DST4
Input
Thermal head print activation instruction signal
12
DST3
Input
Thermal head print activation instruction signal
13
DST2
Input
Thermal head print activation instruction signal
14
DST1
Input
Thermal head print activation instruction signal
15
TH
-
Thermistor
16
Vdd
Input
Logic power supply (5V)
17
GND
-
GND
18
GND
-
GND
19
Vp
Input
Thermal head drive voltage
20
Vp
Input
Thermal head drive voltage
4-3
4.2 MOTOR AND DETECTOR TERMINALS
Figure 4-2 shows the terminals of the motor control, paper detector and platen position sensor.
Figure 4-2 Motor and Detector Terminals
Table 4-3 Motor and Detector Terminals Assignments
Terminal
Number
Signal Name
Function
1
A
Motor drive signal
2
A
Motor drive signal
3
B
Motor drive signal
4
B
Motor drive signal
5
V
PS
LED anode
(Power supply side of the paper detector)
6
PS
Photo-transistor
(Collector output of a photo-transistor)
7
GND
GND
8
GND
Platen position sensor (GND)
9
HS
Platen position sensor output
1
9
4-4
4.3 CAUTION IN CONNECTION
Pay attention to the following during installation of the printer.
Always remove or install the thermal head controls vertically while holding the reinforcement
portion of the FFC.
Do not bend the FFC. If the FFC must be bent unavoidably, try to do so without removing the
reinforcement sheet from the reinforcement portion of the FFC.
Always remove or install the motor and sensor connector vertically while holding the connector
housing.
If the connectors are not connected properly, it may damage the printer, cables or connectors.
5-1
5
DRIVE METHOD
5.1 THERMAL HEAD DRIVE TIMING
Input of print data
Input of DAT and CLK transfer the print data to the shift register in the serial input. "High"
means printing and "Low" means no-printing in DAT. DAT data is read in at the rising edge of
the CLK inputs. The transferred line of data is stored in the latch register by turning LATCH to
"Low".
Input of the head activation pulse
Setting the DST on "High" drives the heat elements of the thermal head. Select the block to be
activated and drive for the time calculated using the formula shown in "3.6 CONTROLLING
THE HEAD ACTIVATION (DST) PULSE WIDTH", then set the DST to "Low".
Figure 5-1 shows the example of timing chart of the thermal head driving.
1:
The print data for next dot line can be transferred immediately after storing the print data into the latch register.
Figure 5-1 Example of Timing Chart of the Thermal Head Driving
CHAPTER
CLK
DAT
DST
Latching data
Data transfer
1
LATCH
Data transfer
5-2
5.2 MOTOR DRIVE TIMING
To print, the phase of motors need to be synchronized with that of the thermal head.
As example, the print method which divides one dot line to two groups; the block 1,3, and 5 and the
block 2,4, and 6, and prints each group data for each step of the motor is described below.
The basic pulse width of the motor drive pulse, Tm, is a value (unit: msec) of the reciprocal number of
the driving frequency calculated using equation (1) of "3.3 PAPER FEED CHARACTERISTICS".
Pause State
Transfer the print data to the thermal head according to "5.1 THERMAL HEAD DRIVE
TIMING".
Start up phase
Excite the phase which is output just before the motor stops for the time of the start up step
shown in Table 3-5.
1st line, 1st step
Drive the motor by one step (1st step). The step time should be the acceleration 1st step time
or Tm, whichever is longer.
Set DST for the block 1, 3, and 5 to "High" in synchronization with the motor drive.
After setting DST to "High", set DST to "Low" when the driving time calculated in "3.6
CONTROLLING THE HEAD ACTIVATION (DST) PULSE WIDTH" has passed.
Move to the 2nd step after completion of the 1st step time of the motor and the activation of
blocks 1, 3, 5.
1st line, 2nd step
Drive the motor by one step (2nd step). As to how much step time is output, compare Tm with
the time that was taken in the previous step.
(1) In case Tm < the time that was taken in the previous step,
the next closest acceleration step time to the previous step time or Tm, which is longer, is
output.
(2) in case Tm > the time that was taken in the previous step,
the closest acceleration step time to Tm and the acceleration step time that is larger than Tm,
are output.
Set DST for blocks 2, 4, and 6 to "High" in synchronization with the motor drive. After setting
DST to "High", set DST to "Low" after completion of the head activation time. Transfer the print
data of the next dot line to the thermal head after completion of printing for blocks 2, 4, and 6.
Move to the 2nd dot line after completion of the 2nd step time of the motor and the transfer of
print data for the next dot line.
5-3
2nd line, 1st step
Drive the motor by one step (3rd step). As to how much step time is output, compare Tm with
the time that was taken in the previous step.
(1) in case Tm < the time that was taken in the previous step
the next closest acceleration step time to the previous step time or Tm, which is longer, is
output.
(2) in case Tm > the time that was taken in the previous step
the closest acceleration step time to Tm and the acceleration step time that is larger than Tm,
are output.
Activate blocks 1, 3, and 5 in the same manner as the 1st line.
2nd line, 2nd step
Drive the motor by one step (4th step). As to how much step time is output, compare Tm with
the time that was taken in the previous step.
(1) in case Tm < the time that was taken in the previous step
the next closest acceleration step time to the previous step time or Tm, which is longer, is
output.
(2) in case Tm > the time that was taken in the previous step
the closest acceleration step time to Tm and the acceleration step time that is larger than Tm,
are output.
Activate blocks 2, 4, and 6 in the same manner as the 1st dot line, then transfer the next dot line
data.
Print each line in the same manner continuously.
5-4
Figure 5-2 shows an example of the motor drive timing chart.
Figure 5-2 Example of Motor Drive Timing Chart
A
B
A
B
CLK
DST
1,3,5
Block
2,4,6
Block
1,3,5
Block
2,4,6
Block
DAT
LATCH
2
ND
STEP OF
THE 1
ST
DOT LINE
1
ST
STEP OF
THE 2
ND
DOT LINE
2
ND
STEP OF
THE 2
ND
DOT LINE
1
ST
STEP OF
THE 1
ST
DOT LINE
START
STOP
6-1
6
HOUSING DESIGN GUIDE
6.1 SECURING THE PRINTER
The main body of the printer and platen must be secured to the outer case separately with screws.
6.1.1 Printer Mounting Method
Secure the printer in the 3 locations shown below (a,b,c). Holes A and B are used for positioning the
main body of the printer.
See "CHAPTER 7 APPEARANCE AND DIMENSIONS" for locations and dimensions.
Figure 6-1 How to Secure the Printer
Recommended Screws
The recommended mounting screws are as follows:
1)
Screw
:
M2.0 cross-recessed pan head machine screw
2)
Screw
:
Pan head tapping screw 2.0 to secure resinated material
CHAPTER
6-2
6.1.2 Mounting Platen Block
Secure the platen block in the 2 locations shown below (a,b). Holes A and B are used for positioning the
printer main body.
See "CHAPTER 7 APPEARANCE AND DIMENSIONS" for locations and dimensions.
Figure 6-2 How to Secure the Platen Block
Recommended Screws
The recommended mounting screws are as follows:
Screw
:
M2.0 cross-recessed pan head machine screw
The nominal size of the screw should be the wall thickness of the outer case plus 2 mm. To secure the
platen block to the wall of a thickness of 2 mm, screws of the nominal size of 4 mm should be used.
Platen Block
Screw (2 pieces)
6-3
6.1.3 Precautions for Securing the Printer
Pay attention to the following when designing the case and securing the printer. Failure to follow these
instructions may cause deterioration of print quality, paper skew, paper jam, noise or damage.
Prevent excessive force or torsion when securing the printer.
Remove the platen block before securing the printer.
The bracket for the platen block is made of aluminum. Secure it with an appropriate torque.
Design the case so that the thermal head control terminals can move 1 to 2 mm to compensate
for the head moving.
If the FFC for the thermal head control touches the bottom of the outer case, the FFC will
disconnect and/or short-circuit. Leave a space of approximately 0.3 mm between the bottom of
the outer case where the FFC passes through and the bottom of the printer mechanism.
Secure the platen block to the printer correctly as shown in Figure 7-1. The platen block should
not be used in any other way than as described in Figure 7-1.
6-4
6.2 LAYOUT OF PRINTER AND PAPER
The printer can be laid out as shown in Figure 6-3 according to the loading direction of the
paper.
Design the paper outlet with an angle of 60 to 90
.
Design the paper inlet with an angle of 90
or more.
Figure 6-3 Paper Path
6.3 WHERE TO MOUNT THE PAPER HOLDER
When determining the layout of the paper holder, note the following:
Hold the paper so that the paper is straight to the paper inlet without any horizontal shifting, and
the center axis of the paper roll is parallel with the printer.
Keep the paper feed force to 0.49N (50 gf) or less.
Mount the platen block to the paper holder cover.
For the rotation support point, see CHAPTER 7 APPEARANCE AND DIMENSIONS.
6.4 SETTING THE PAPER
Follow these precautions when setting the paper.
Be sure to use the recommended paper described in this technical reference.
Place the paper roll into the holder facing the thermal surface outward. Also, do not use paper
with edges that are pasted or have turnups at the start of the roll. If they need to be used
unavoidably, replace with new paper roll as soon as possible before the entire roll is used up.
Keep the paper feed force to 0.49N (50 gf) or less.
PAPER DETECTOR
THERMAL PAPER ROLL
The distance between the paper detector and
the heat element is approximately 7 mm.
THERMAL
HEAD
PLATEN
HEAT ELEMENT
Paper outlet angle (
1
): 60
1
90
Paper inlet angle (
2
):
2
90
1
Facing thermal surface outward
2
6-5
6.5 POSITIONING THE PAPER CUTTER
Design the position of the paper cutter so that the paper cutter is within the recommended range as
shown below.
If the distance between the edge of the paper cutter and position reference hole A of the printer is less
than 6.9 mm, the paper cutter may interfere with the platen block when it is opened or closed.
If the distance between them is more than 7.5 mm, the paper is not pressed against the cutter edge and
it is difficult to cut. Therefore, position the paper cutter so the distance between the edge of the paper
cutter and the position reference hole A of the printer is from 6.9 to 7.5 mm.
Figure 6-4 shows the recommended position
Figure 6-4 Paper Cutter Mounting Position
Use a cutter with a sharp edge so that paper can be cut easily without excessive force.
Figure 6-5 shows the shape of the blade of the paper cutter that should be used.
Figure 6-5 The Blade of the Paper Cutter
In the left cutter of Figure 6-5, the cut paper may be caught by the blade of the cutter and rolled inside.
Therefore, use a cutter with the shape of a blade that will not catch the cut paper as in Figure 6-5 to the
right.
A
Recommended range of the edge
position of the paper cutter
The Blade of the Cutter
The Blade of the Cutter
No Good
Good
6-6
6.6 OUTER CASE STRUCTURE
Figure 6-6 shows a sample of an outer case.
*1 Provide a gap of a few mm between the printer and the outer case to allow for cooling of the thermal head.
*2 When the FFC contacts bottom of the outer case strongly, disconnection and short circuit may occur. Provide a gap
between the printer main body and the outer case.
Figure 6-6 Sample Outer Case Structure
*1
*2
7-1
7
APPEARANCE AND DIMENSIONS
Figure 7-1, 7-2 and 7-3 show the appearance and external dimensions of the LTPH245.
CHAPTER
7-2
Figure 7-1 Appearance and Dimensions
Unit : mm
Rotation support range
7-3
Figure 7-2 Printer Main Body Appearance and Dimensions
Unit : mm
7-4
Figure 7-3 Platen Block Appearance and Dimensions
Unit : mm
8-1
8
LOADING/UNLOADING PAPER AND HEAD CLEANING
8.1 LOADING/UNLOADING PAPER PRECAUTIONS
1) Loading paper
Turn the release lever in the direction of the arrow shown in Figure 8-1.
Figure 8-1 Loading Paper (1)
After confirming that the platen block has separated from the printer mechanism, lift the platen
block up.
CHAPTER
Arrow
8-2
Insert the paper vertically into the printer. (See Figure 8-2).
Pull the paper through the paper outlet and replace the platen block into the printer mechanism.
Make sure that the platen block locks with a click.
Opening the platen block exposes the reduction gear which can be damaged if touched.
Therefore, take care not to damage the gear when inserting the paper. Moreover, make sure
there is no foreign matter on the gear.
Figure 8-2 Loading Paper (2)
The paper detector may not operate properly if covered with foreign matter. Therefore, if you
find foreign matter on the sensor, remove it and clean the sensor.
If the paper skews, feed the paper so that it returns to normal, first, then take it out and set it
again.
2) Unloading paper
Open the platen block and remove the paper.
3) Removing jammed paper
Open the platen block and remove any jammed paper.
Do not pull the paper by force.
8-3
8.2 HEAD CLEANING PROCEDURE AND PRECAUTIONS
8.2.1 PRECAUTIONS
1)
Do not clean the thermal head immediately after printing because thermal head and its
periphery are hot during and after printing.
2)
Do not use sandpaper, cutter knives etc. when cleaning. They will damage the heat
elements.
8.2.2 PROCEDURE
1)
Turn the release lever in the direction of the arrow shown in Figure 8-1. After confirming that
the platen block has separated from the printer mechanism, lift the platen block up.
2)
Clean the heat elements using alcohol and a cotton swab.
3)
Wait until the alcohol dries and close the platen block.
Heat Element
Figure 8-3 Head Cleaning Procedure
PDF 
ZIP