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. 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. iii TABLE OF CONTENTS Section Page CHAPTER 1 PRECAUTIONS 1.1 1.2 SAFETY PRECAUTIONS ............................................................................................. DESIGN AND HANDLING PRECAUTIONS ................................................................. 1.2.1 Design Precautions.......................................................................................... 1.2.2 Handling Precautions....................................................................................... 1-1 1-2 1-2 1-4 CHAPTER 2 FEATURES CHAPTER 3 SPECIFICATIONS 3.1 3.2 3.3 3.4 3.5 3.6 3.7 GENERAL SPECIFICATIONS...................................................................................... HEAT ELEMENT DIMENSIONS................................................................................... PAPER FEED CHARACTERISTICS ............................................................................ STEP MOTOR CHARACTERISTICS ........................................................................... 3.4.1 Motor Drive Circuit ........................................................................................... 3.4.2 Motor Timing .................................................................................................... 3.4.3 Precautions for Driving the Motor .................................................................... THERMAL HEAD.......................................................................................................... 3.5.1 Structure of the Thermal Head ........................................................................ 3.5.2 Printed Position of the Data ............................................................................. 3.5.3 Head Resistance.............................................................................................. 3.5.4 Head Voltage ................................................................................................... 3.5.5 Peak Current.................................................................................................... 3.5.6 Thermal Head Electrical Characteristics.......................................................... 3.5.7 Timing Chart .................................................................................................... CONTROLLING THE HEAD ACTIVATION (DST) PULSE WIDTH ............................. 3.6.1 Calculation of Head Activation Pulse Width..................................................... 3.6.2 Calculation of Applied Energy.......................................................................... 3.6.3 Calculation of Head Activation Voltage............................................................ 3.6.4 Calculation of Head Resistance....................................................................... 3.6.5 Determination of Activation Pause Time and Activation Pulse Period............. 3.6.6 Head Activation Pulse Term Coefficient .......................................................... 3.6.7 Head Storage Coefficient................................................................................. 3.6.8 Calculation Sample for the Head Activation Pulse Width ................................ 3.6.9 Thermistor Resistance..................................................................................... 3.6.10 Detecting Abnormal Temperatures of the Thermal Head................................ PAPER DETECTOR ..................................................................................................... 3.7.1 General Specifications ..................................................................................... 3.7.2 Sample External Circuit ................................................................................... iv 3-1 3-3 3-4 3-5 3-6 3-8 3-10 3-12 3-12 3-14 3-15 3-16 3-16 3-17 3-18 3-19 3-19 3-19 3-20 3-20 3-21 3-21 3-22 3-23 3-24 3-26 3-27 3-27 3-28 Section 3.8 Page PLATEN POSITION SENSOR...................................................................................... 3.8.1 General Specification....................................................................................... 3.8.2 Sample External Circuit .................................................................................. 3-29 3-29 3-29 CHAPTER 4 CONNECTING EXTERNAL CIRCUITS 4.1 4.2 4.3 THERMAL HEAD CONTROL TERMINALS ................................................................. MOTOR AND DETECTOR TERMINALS ..................................................................... CAUTION IN CONNECTION........................................................................................ 4-1 4-3 4-4 CHAPTER 5 DRIVE METHOD 5.1 5.2 THERMAL HEAD DRIVE TIMING ................................................................................ MOTOR DRIVE TIMING ............................................................................................... 5-1 5-2 CHAPTER 6 HOUSING DESIGN GUIDE 6.1 6.2 6.3 6.4 6.5 6.6 SECURING THE PRINTER .......................................................................................... 6.1.1 Printer Mounting Method.................................................................................. 6.1.2 Mounting Platen Block ..................................................................................... 6.1.3 Precautions for Securing the Printer ................................................................ LAYOUT OF PRINTER AND PAPER ........................................................................... WHERE TO MOUNT THE PAPER HOLDER............................................................... SETTING THE PAPER ................................................................................................. POSITIONING THE PAPER CUTTER ......................................................................... OUTER CASE STRUCTURE ....................................................................................... 6-1 6-1 6-2 6-3 6-4 6-4 6-4 6-5 6-6 CHAPTER 7 APPEARANCE AND DIMENSIONS CHAPTER 8 LOADING/UNLOADING PAPER AND HEAD CLEANING 8.1 8.2 LOADING/UNLOADING PAPER PRECAUTIONS ....................................................... HEAD CLEANING PROCEDURE AND PRECAUTIONS ............................................. 8.2.1 PRECAUTIONS ............................................................................................... 8.2.2 PROCEDURE .................................................................................................. v 8-1 8-3 8-3 8-3 FIGURES Figure Page 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-11 3-12 3-13 Heat Element Dimensions ............................................................................................ Print Area ...................................................................................................................... Sample Drive Circuit ..................................................................................................... Input Voltage Signals for the Sample Drive Circuit ....................................................... Motor Start/Stop Timing ................................................................................................ Motor Drive Timing Chart.............................................................................................. Thermal Head Block Diagram....................................................................................... Printed Position of the Data .......................................................................................... Head Resistance Rank Sample.................................................................................... Timing Chart ................................................................................................................. Thermistor Resistance vs. Temperature....................................................................... Sample External Circuit of the Paper Detector ............................................................. Sample External Circuit of the Platen Position Sensor ................................................. 3-3 3-3 3-6 3-7 3-8 3-10 3-13 3-14 3-15 3-18 3-24 3-28 3-29 4-1 4-2 Thermal Head Control Terminals.................................................................................. Motor and Detector Terminals ...................................................................................... 4-1 4-3 5-1 5-2 Example of Timing Chart of the Thermal Head Driving ................................................ Example of Motor Drive Timing Chart........................................................................... 5-1 5-3 6-1 6-2 6-3 6-4 6-5 6-6 How to secure the printer.............................................................................................. How to secure the Platen Block .................................................................................... Paper Path .................................................................................................................... Paper Cutter Mounting Position .................................................................................... The Blade of the Paper Cutter ...................................................................................... Sample Outer Case Structure....................................................................................... 6-1 6-2 6-4 6-5 6-5 6-6 7-1 7-2 7-3 Appearance and Dimensions........................................................................................ Printer Main Body Appearance and Dimensions .......................................................... Platen Block Appearance and Dimensions................................................................... 7-2 7-3 7-4 8-1 8-2 8-3 Loading Paper (1) ......................................................................................................... Loading Paper (2) ......................................................................................................... Head Cleaning Procedure............................................................................................. 8-1 8-2 8-3 vi TABLES Table Page 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-11 3-12 3-13 General Specifications .................................................................................................. Sample Motor Drive Frequency .................................................................................... General Specifications of the Motor.............................................................................. Excitation Sequence ..................................................................................................... Acceleration Steps ........................................................................................................ Blocks and Activated Heat Elements ............................................................................ Head Resistance Ranks ............................................................................................... Head Voltage ................................................................................................................ Thermal Head Electrical Characteristics....................................................................... Activation Pulse Width .................................................................................................. Temperature and Thermistor Resistance ..................................................................... Absolute Maximum Ratings of Detectors...................................................................... Detectors Input/Output Conditions................................................................................ 3-1 3-4 3-5 3-7 3-11 3-14 3-15 3-16 3-17 3-23 3-25 3-27 3-28 4-1 4-2 4-3 Recommended Connectors .......................................................................................... Thermal Head Control Terminal Assignments.............................................................. Motor and Detector Terminals Assignments................................................................. 4-1 4-2 4-3 vii CHAPTER 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. 1-1 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 MΩ 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 mΩ 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: Vdd ↔ GND: 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: At power OFF: approximately 10µF approximately 1µF 1) Vcc (5 V) 1) Vp → → 2) 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. 1-2 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. 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. Design so that the paper feed load is 0.49N (50 gf) or less. The lever should be used when removing and installing the platen block. It should never be pulled by force. 1-3 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. 1-4 CHAPTER 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 NiMH batteries or two Lithium-ion batteries can also be used. Compact and light weight 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 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. 1 2 2-1 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. 2-2 CHAPTER 3 SPECIFICATIONS 3.1 GENERAL SPECIFICATIONS Table 3-1 General Specifications Item Print method Dots per line Resolution Print width Maximum printing speed Paper feed pitch Head temperature detection Platen position detection Out-of-paper detection Operating voltage range VP line (for head and motor drive) Vdd line (for head logic) Current consumption For driving the head (VP) For driving the motor (VP) For head logic (Vdd) 1 2 Specification Thermal dot line printing 384 dots 8 dots/mm 48 mm 1 200 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) 0.125 mm Via thermistor Via mechanical switch Via photo interrupter 7 4.2 V to 8.5 V (equivalent to four through six Ni-Cd or Ni-MH batteries, or two lithium-ion batteries) 4.5 V to 5.5 V Average: 2 1.8 A (at 5 V), 2.6 A (at 7.2 V), 2.8 A (at 8.0 V) Maximum: 2 2.1 A (at 5 V), 3.0 A (at 7.2 V), 3.3 A (at 8.0 V) Maximum 0.46 A Maximum 0.01 A 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. When the number of simultaneously activated dots is specified as 64. 3-1 Table 3-1 General Specifications (Continued) Item Operating temperature range Storage temperature range Life span (at 25°C and rated energy) Activation pulse resistance Abrasion resistance Paper width Paper feeding force Paper holding force Dimensions (width×depth×height) Weight Recommended thermal paper 3 4 5 Specification 3 -5°C to 50°C No condensation 3 -25°C to 70°C No condensation 100 million pulses or more (print ratio=12.5%) 50 km or more 58 +0 - 1 mm 0.49N (50 gf) or more 0.78N (80 gf) or more 76.8 × 38.0 × 16.0 mm (excluding lever) Approximately 46 g TF50KS-E2C (65 µm paper) TP50KJ-R (65 µm paper) AP50KS-E (65 µm paper) from Nippon Paper Industries HP220-AB1 (65 µm paper) from Mitsubishi Paper Industries 4 PD160R-N (75 µm paper) from Oji Paper Industries Outside this range, prining may blot or be light. When the print ratio is high, this thermal paper may generate a noise during printing. 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. 3-2 3.2 HEAT ELEMENT DIMENSIONS The printer contains a thermal head with 384 heat elements (dot-size). 48 mm (384 DOTS) 0.125 mm 0.125 mm Figure 3-1 Heat Element Dimensions +0 58 -1 mm (PAPER WIDTH) 5 mm 48 mm (PRINTING WIDTH) 5 mm 0.125 mm (PAPER FEED PITCH) Figure 3-2 Print Area 3-3 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) 473 pps 605 pps 770 pps 968 pps 1000 pps 1000 pps 4.2 V 5V 6V 7.2 V 8V 8.5 V 3-4 3.4 STEP MOTOR CHARACTERISTICS Table 3-3 General Specifications of the Motor Item Type Number of phases Drive method Excitation Winding resistance per phase Rated voltage Rated current Maximum current consumption Drive frequency 1 Specification PM 4-phase Bipolar chopper 2-2 phase 14 Ω ±10% 4.2 - 8.5 V 1 0.23 A/phase, 0.15A/phase 0.46 A 50 - 1000 pps (according to drive voltage) See 3.4.3 Precautions for Driving the Motor. 3-5 3.4.1 Motor Drive Circuit (1) Sample Drive Circuit Sample drive circuits for the motor are shown in Figure 3-3. Vp NC 9 6 1 11 20 15 13 LB1843V 14 74HC32 4 5 2 3 18 19 10µF 50V 0.51Ω 1% 1/2W 17 12 Vcc Vcc 10KΩ 1 15 13 2 4 PH1 PH2 PH3 PH4 0.01µF 10%,10% CTCRL Vcc 1KΩ 1% Vcc 0.01µF 10%,10% 3KΩ 1% 7 16 3 11 74HC123A 6 0.1µF 1SS294 14 3KΩ 1% 0.01µF 10%,10% 10 12 8 1.8KΩ 1% 0.01µF 10%,10% 1KΩ 1% 5 9 Vcc 10KΩ 13 12 18 19 14 µPC1060 Vcc 1 0.1µF 2 3 2.7KΩ 1% 0.1µF 9 1 11 20 17 3.3KΩ 1% LB1843V 10µF 50V 15 4 5 Figure 3-3 Sample Drive Circuit 3-6 Vp 6 74HC32 NC 2 3 0.51Ω 1% 1/2W 2 3 1 4 A B A B (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 Step 1 A B A B Low High High Low Sequence Step 2 Step 3 High High Low Low High Low Low High Step 4 Low Low High High H A L H B L H A L H B L 1 DOT LINE Figure 3-4 Input Voltage Signals for the Sample Drive Circuit 3-7 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. 1 DOT LINE PH1 H L PH2 H L H PH3 L H PH4 L STOP PAUSE START STEP STATE STEP PRINT STEP Figure 3-5 Motor Start/Stop Timing 3-8 PRINT STEP (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. 3-9 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 overtorque 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: µs) 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 230mA T1 T1 T1 T1 150mA PH1 PH2 PH3 PH4 Start (6.58ms) 1st step 2nd step 3rd step 4th step (6.58ms) (4.07ms) (3.14ms) (2.64ms) Set the 1st setting current at CTCRL=“High”: Set the 2nd setting current at CTCRL=“Low”: 0.23 (A) 0.15 (A) Figure 3-6 Motor Drive Timing Chart 3-10 (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. 2. 3. 4. 5. Output start step (6580 (µs)) for the time calculated using equation (1) Output first step for the first acceleration step time Output second step for the second acceleration step time Output nth step for the nth step acceleration time 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 start 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Speed (pps) 152 246 318 379 433 493 547 597 644 687 728 768 805 840 874 907 939 970 1000 3-11 Step Time (µs) 6580 6580 4066 3140 2636 2311 2028 1828 1675 1553 1456 1374 1302 1242 1191 1144 1103 1065 1031 1000 3.5 3.5.1 THERMAL HEAD 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. 3-12 Vp Heat Element Output Driver Latch Register Shift Register DAT CLK LATCH DST6 DST5 DST2 DST1 TH Thermistor Vdd GND Figure 3-7 Thermal Head Block Diagram 3-13 DOT 1 DOT 64 Block1 DOT 65 DOT 128 DOT 129 DOT 256 Blcok2 DOT 257 DOT 320 Block5 DOT 321 DOT 384 Block6 Table 3-6 Blocks and Activated Heat Elements 3.5.2 Block Number Heat Element Number Dots / DST 1 2 3 4 5 6 1 - 64 65 - 128 129 - 192 193 - 256 257 - 320 321 - 384 64 64 64 64 64 64 Printed Position of the Data Data dots from 1 to 384 which are transferred through DAT are printed as shown in Figure 3-8. PAPER PAPER FEED DIRECTION PRINT SURFACE DATA PRINT SEQUENCE 1 2 3 4 5 6 ............................ 382 383 384 LTPH245 PRINTER MECHANISM DATA INPUT SEQUENCE 1 2 3 4 5 6 . . . . . . 382 383 384 Figure 3-8 Printed Position of the Data 3-14 DATA IN 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 B C 178.6 to 195.5 Ω 161.6 to 178.5 Ω 144.5 to 161.5 Ω * 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 3-15 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 3.5.5 Voltage Range Head drive voltage Vp 4.2 to 8.5 V Head logic voltage Vdd 4.5 to 5.5 V 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): N × Vp Ip= RH Ip: N: Vp: RH: Peak current (A) Number of dots that are driven simultaneously Head drive voltage (V) Head resistance (Ω) 3-16 3.5.6 Thermal Head Electrical Characteristics Table 3-9 Thermal Head Electrical Characteristics Item Simbol Conditions (Vdd=4.5 to 5.5V, Ta=0 to 50°C) Rated Values Unit MIN TYP MAX Head resistance RH 144.5 170 195.5 Ω Head drive voltage Vp 4.2 7.2 8.5 V Head drive current Ip 1.3 2.6 3.5 A Logic block voltage Vdd 4.5 5.0 5.5 V Waiting for activation Ta= 25°C fclk=4MHz,DAT=fixed - - 0.5 mA - - 6 mA - - 10 mA 0.8×Vdd - Vdd V 0 - 0.2×Vdd V - - 3 µA - - 0.5 µA - - 3 µA DST - - 55 µA CLK - - -3 µA - - -0.5 µA - - -3 µA - - -0.5 µA - - 1.0 µA - - 4 MHz Logic block current Idd max. common activated dot 64 "High" input voltage Vih fclk=4MHz,DAT=1/2fclk CLK,DAT,LATCH,DST "Low" input voltage Vil CLK,DAT,LATCH,DST CLK "High" input DAT current LATCH "Low" input current DAT Iih Iil LATCH Ta=25°C Vdd=5.0(V) Vih=5.0(V) Ta=25°C Vdd=5.0(V) Vil=0(V) DST Driver leak current I leak Vp=7(V), for 1 bit CLK frequency fclk 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 3-17 3.5.7 Timing Chart Figure 3-10 Timing Chart 3-18 3.6 3.6.1 CONTROLLING THE HEAD ACTIVATION (DST) PULSE WIDTH 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): E×R t= 2 ×C×D V t: E: V: R: C: D: 3.6.2 Head pulse width (ms) Standard applied energy (mj) Applied voltage (V) Head resistance (Ω) Head pulse term coefficient Heat storage coefficient See Section 3.6.2. See Section 3.6.3. See Section 3.6.4. See Section 3.6.6. See Section 3.6.7. 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 - TC × (TX - 25) ) TX: Detected temperature using the thermistor (°C) TC : Temperature coefficient 0.003373 1 1 The thermistor resistance value at TX (°C). See Section 3.6.8. 3-19 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 + 25 + (RC + rC ) × N ) R= RH 2 RH: Head resistance depending on resistance ranks rank A (178.6 - 195.5Ω): 195.5 (Ω) rank B (161.6 - 178.5Ω): 178.5 (Ω) rank C (144.5 - 161.5Ω): 161.5 (Ω) 25: Wiring resistance in the thermal head (Ω) RC: Common terminal wiring resistance in the thermal head: 1 rC: Wiring resistance between VP and GND (Ω) N: Number of dots driven simultaneously 1 0.2 (Ω) It indicates a series resistance of wire and relay switching circuits used between the FFC terminals and power supply. 3-20 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 3-21 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. N T’=T+ 6 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- T 31936 3-22 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 Head Drive Voltage (V) 4.2 5.0 6.0 7.2 8.0 8.5 Thermistor Temperature ℃ 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 Motor Drive Frequency (PPS) 100 9.91 8.94 7.97 7.00 6.03 5.06 4.09 3.12 2.14 6.10 5.51 4.91 4.31 3.71 3.11 2.52 1.92 1.32 3.79 3.42 3.05 2.68 2.30 1.93 1.56 1.19 0.82 2.41 2.17 1.94 1.70 1.46 1.23 0.99 0.76 0.52 1.87 1.68 1.50 1.32 1.14 0.95 0.77 0.59 0.40 1.62 1.46 1.30 1.14 0.98 0.83 0.67 0.51 0.35 200 300 4.67 3.77 2.87 1.98 2.70 1.86 4.53 3.98 3.42 2.87 2.32 1.77 1.22 3.50 3.15 2.81 2.47 2.13 1.78 1.44 1.10 0.76 2.22 2.00 1.79 1.57 1.35 1.13 0.92 0.70 0.48 1.72 1.55 1.39 1.22 1.05 0.88 0.71 0.54 0.37 1.49 1.35 1.20 1.05 0.91 0.76 0.62 0.47 0.32 3.22 2.70 2.18 1.66 1.15 3.29 2.96 2.64 2.32 2.00 1.68 1.35 1.03 0.71 2.09 1.88 1.68 1.47 1.27 1.07 0.86 0.66 0.45 1.62 1.46 1.30 1.14 0.99 0.83 0.67 0.51 0.35 1.40 1.27 1.13 0.99 0.85 0.72 0.58 0.44 0.30 400 500 600 700 800 900 1000 Do not use this area because paper feed errors may occur because of the motor torque. 1.77 2.08 1.58 1.09 2.00 1.52 1.05 2.21 1.90 1.60 1.29 0.98 0.68 1.99 1.79 1.60 1.40 1.21 1.01 0.82 0.62 0.43 1.54 1.39 1.24 1.09 0.94 0.79 0.64 0.48 0.33 1.34 1.21 1.07 0.94 0.81 0.68 0.55 0.42 0.29 1.83 1.53 1.24 0.94 0.65 1.91 1.72 1.54 1.35 1.16 0.97 0.79 0.60 0.41 1.48 1.34 1.19 1.05 0.90 0.76 0.61 0.47 0.32 1.28 1.16 1.03 0.91 0.78 0.66 0.53 0.40 0.28 1.47 1.01 1.48 1.20 0.91 0.63 1.17 0.89 0.61 1.67 1.49 1.31 1.12 0.94 0.76 0.58 0.40 1.43 1.29 1.15 1.01 0.87 0.73 0.59 0.45 0.31 1.24 1.12 1.00 0.88 0.76 0.63 0.51 0.39 0.27 1.27 1.09 0.92 0.74 0.56 0.39 1.39 1.26 1.12 0.98 0.85 0.71 0.57 0.44 0.30 1.21 1.09 0.97 0.85 0.73 0.62 0.50 0.38 0.26 1.24 1.07 0.90 0.72 0.55 0.38 1.23 1.10 0.96 0.83 0.69 0.56 0.43 0.29 1.18 1.06 0.95 0.83 0.72 0.60 0.49 0.37 0.26 1.05 0.88 0.71 0.54 0.37 1.20 1.07 0.94 0.81 0.68 0.55 0.42 0.29 0.93 0.80 0.67 0.54 0.41 0.28 1.04 0.93 0.82 0.70 0.59 0.48 0.36 0.25 0.91 0.80 0.69 0.58 0.47 0.36 0.25 Note) The above table shows values for recommended 65 µ thermal paper, resistance rank B, Rc+rc=0.20, and N=64. 3-23 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. 3-24 3.6.9 Thermistor Resistance The resistance of the thermistor at the operating temperature TX (°C) is determined using the following equation (10). Equation (10): RX=R25 × EXP RX: R25: B: TX: EXP (A): B× 1 1 - 273 + TX 298 Resistance at operating temperature Tx (°C) 15 kΩ ± 10% (25°C) 3440 k ± 3% Operating temperature (°C) The Ath power of natural logarithm e (2.71828) [Rating] Operating temperature range: -40°C to +125°C 1000 100 RESISTANCE (kΩ Ω) 10 1 -40 -30 -20 -10 0 10 20 30 40 50 60 TEMPERATURE (°°C) Figure 3-11 Thermistor Resistance vs. Temperature 3-25 70 80 90 100 Table 3-11 Temperature and Thermistor Resistance Temperature (°°C) -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 Thermistor Resistance (kΩ Ω) 375.54 275.40 204.55 153.76 116.89 89.82 69.71 54.61 43.17 34.42 27.66 22.40 18.27 15.00 12.40 10.31 Temperature (°°C) 40 45 50 55 60 65 70 75 80 85 90 95 100 3-26 Thermistor Resistance (kΩ Ω) 8.63 7.26 6.14 5.22 4.46 3.83 3.30 2.86 2.48 2.17 1.90 1.67 1.47 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 kΩ), and reactivate the heat elements when a temperature of 60 °C or lower (RTH ≥ 4.46 kΩ) 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 kΩ)). (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. 3-27 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 LED (input) Forward current Reverse voltage Allowable current Phototransistor Collector-to-emitter (output) voltage Emitter-to-collector voltage Collector current Collector loss Operating temperature Storage temperature 3-28 Rating IF VR P VCEO 50 mA 5V 70 mW 20 V VECO 5V IC PC Topr Tstg 20 mA 70 mW -20°C to + 80°C -30°C to + 100°C Table 3-13 Detectors Input/Output Conditions Item LED (input) Phototransistor (output) Transfer characteristics 3.7.2 Symbol Forward voltage Reverse current VF IR IF=10mA VR=5V Standard Max. 1.2V − 1.6V 10µA I CEO If=0mA, VCE=10V − 200nA IC IF=10mA, VCE=5V − 350µA ILEAK VCE(sat) IF=10mA, VCE=5V IF=10mA, IC=50µA − − 1µA 0.5V Dark current Photo electric current Leak current Collector saturation voltage Response time (at rise) Response time (at fall) Conditions tr IC=1mA, VCC=5V 5µs - tf RL=100Ω 5µs − Sample External Circuit LTPH245 Vdd (5V) 47kΩ Vdd (5V) 220Ω Photo interruptor 74HC04 PS VPS CPU Port 470pF GND GND * The PS signal is high when there is no paper. Figure 3-12 Sample External Circuit of the Paper Detector 3-29 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 mΩ or less 3.8.2 Sample External Circuit Vdd (5v) LTPH245 R=100kΩ HS CPU Port C=0.1µF GND Switch GND * When the platen block is open 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. 3-30 CHAPTER 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. 1 2 4.1 External Circuit Functions Thermal head control Number of Pins 20 Motor control, Paper detector Platen position detection 9 Recommended Connectors (in the external circuit side) Molex Co., Ltd. 52044-2010 (horizontal type) 52045-2010 (vertical type) 5597-20APB (horizontal type) 5597-20CPB (vertical type) Molex Co., Ltd. 53047-0910 (vertical type) 53048-0910 (horizontal type) 51047-0910 (transmission type) THERMAL HEAD CONTROL TERMINALS Figure 4-1 shows the terminals configuration of the FFC thermal head control terminals. 1 20 Figure 4-1 Thermal Head Control Terminals 4-1 Table 4-2 Thermal Head Control Terminal Assignments Terminal Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Signal Name Vp Vp GND GND GND DAT CLK LATCH DST6 DST5 DST4 DST3 DST2 DST1 TH Vdd GND GND Vp Vp Input/ Output Input Input Input Input Input Input Input Input Input Input Input Input Input Input Function Thermal head drive voltage Thermal head drive voltage GND GND GND Print data input (serial input) Synchronizing signal for print data transfer Print data latch (memory storage) Thermal head print activation instruction signal Thermal head print activation instruction signal Thermal head print activation instruction signal Thermal head print activation instruction signal Thermal head print activation instruction signal Thermal head print activation instruction signal Thermistor Logic power supply (5V) GND GND Thermal head drive voltage Thermal head drive voltage 4-2 4.2 MOTOR AND DETECTOR TERMINALS Figure 4-2 shows the terminals of the motor control, paper detector and platen position sensor. 1 9 Figure 4-2 Motor and Detector Terminals Table 4-3 Motor and Detector Terminals Assignments Terminal Number Signal Name 1 A Motor drive signal 2 A Motor drive signal 3 B Motor drive signal 4 B Motor drive signal 5 6 VPS PS Function LED anode (Power supply side of the paper detector) Photo-transistor (Collector output of a photo-transistor) 7 GND GND 8 GND Platen position sensor (GND) 9 HS Platen position sensor output 4-3 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. 4-4 CHAPTER 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 CLK Data transfer Data transfer DAT LATCH Latching data DST 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 5-1 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. 5-2 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. 5-3 Figure 5-2 shows an example of the motor drive timing chart. STOP START 1ST STEP OF THE 1ST DOT LINE 2ND STEP OF THE 1ST DOT LINE 1,3,5 Block 2,4,6 Block 1ST STEP OF THE 2ND DOT LINE 2ND STEP OF THE 2ND DOT LINE A B A B CLK DAT LATCH DST 1,3,5 Block Figure 5-2 Example of Motor Drive Timing Chart 5-4 2,4,6 Block CHAPTER 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 6-1 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. Platen Block Screw (2 pieces) 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. 6-2 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. 6-3 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. Paper outlet angle (θ 1): 60°≤θ 1≤90° Paper inlet angle (θ 2): θ 2≥90° HEAT ELEMENT THERMAL HEAD THERMAL PAPER ROLL PLATEN θ1 θ2 Facing thermal surface outward PAPER DETECTOR The distance between the paper detector and the heat element is approximately 7 mm. 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. 6-4 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 Recommended range of the edge position of the paper cutter A 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. The Blade of the Cutter The Blade of the Cutter No Good Good 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. 6-5 6.6 OUTER CASE STRUCTURE *2 *1 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 6-6 CHAPTER 7 APPEARANCE AND DIMENSIONS Figure 7-1, 7-2 and 7-3 show the appearance and external dimensions of the LTPH245. 7-1 Rotation support range Unit : mm Figure 7-1 Appearance and Dimensions 7-2 Unit : mm Figure 7-2 Printer Main Body Appearance and Dimensions 7-3 Unit : mm Figure 7-3 Platen Block Appearance and Dimensions 7-4 CHAPTER 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. Arrow Figure 8-1 Loading Paper (1) After confirming that the platen block has separated from the printer mechanism, lift the platen block up. 8-1 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. 8-2 8.2 8.2.1 8.2.2 HEAD CLEANING PROCEDURE AND PRECAUTIONS 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. elements. They will damage the heat 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 8-3