JP2011126140A - Thermal printer and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal printer capable of maintaining required minimum image quality while attaining high-speed printing in batch driving applied when a printing rate is low, and capable of preventing a decline in printing performance in divided driving applied when the printing rate is high, and a program. <P>SOLUTION: A driving pattern is changed into batch driving for batch-driving each block and into divided driving for driving each block dividedly according to the printing rate. In the case of batch driving, energization to each heating element by each driving part in every ON period of driving pulses is repeated a plurality of times, and in the case of divided driving, energization to each heating element by each driving part in every ON period of driving pulses is made one time. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thermal printer and a program.

  Conventionally, in a thermal printer, an image is formed in a main scanning direction by a line thermal head having a large number of heating elements arranged in a line, and a sheet is conveyed in the sub-scanning direction, which is a direction orthogonal to the main scanning direction. The image is formed on the printing paper. In such a thermal printer, printing is performed by energizing and heating the heating elements. When using transfer paper and an ink ribbon, the ink ribbon ink is melted or sublimated on the surface of the print paper and transferred to the transfer paper. To form an image. When thermal paper is used as printing paper, an image is formed on the thermal paper by thermal coloring.

  In recent years, in a line thermal head, by providing a plurality of drive ICs to which a strobe signal STB is input, it is possible to shift the print drive timing of each heating element. For example, when a thermal printer is applied to a printer with a small power supply capacity, each drive IC is driven separately in advance (hereinafter referred to as divided drive), thereby avoiding simultaneous use of power by each drive IC. Can do. On the other hand, when the thermal printer is applied to a receipt printer used in a POS system or the like, the printing speed can be increased by simultaneously driving the drive ICs (hereinafter referred to as collective driving).

  In addition, in order to prevent image density unevenness due to speed fluctuations of the paper transport motor, a technique for repeatedly energizing the heating element by each drive IC for each ON period of the motor drive pulse is performed a plurality of times. Is disclosed (see Patent Document 1).

  According to the technique disclosed in Patent Document 1 described above, energization of the heating element by each drive IC is repeatedly performed a plurality of times in both divided driving and collective driving.

  However, in the split drive, the time required for driving one line is several times as many as the number of divisions compared to the collective drive, so that the rotational speed of the motor is modulated and the heating element is repeatedly energized a plurality of times. Since the width of the strobe signal must also be changed, there is a problem that a CPU with low processing capability is loaded and print performance is degraded.

  The present invention has been made in view of the above, and in the collective driving applied when the printing rate is low, the minimum required image quality can be maintained while increasing the printing speed, An object of the present invention is to provide a thermal printer and a program capable of preventing a decrease in printing performance in divided driving applied when the printing rate is high.

  In order to solve the above-described problems and achieve the object, a thermal printer according to the present invention includes a motor that rotates in response to an input of a drive pulse, and a plurality of heating elements arranged in a row. A line thermal head that prints on a recording sheet conveyed by power from the motor by selective heat generation, and a plurality of driving units that respectively drive a plurality of blocks that are units obtained by dividing the heating elements of the line thermal head The drive pattern is changed to collective drive for collectively driving the blocks according to the printing rate and divided drive to drive the blocks in a divided manner. In each of the ON periods, the energization of each heating element by each driving unit is repeated a plurality of times, and in the case of the divided driving, every one ON period of the driving pulse. Characterized in that it and a printing control unit that once the power supply to the heating elements by said respective driving parts.

  The program of the present invention includes a line thermal head that prints by selective heat generation of each heating element on a recording sheet conveyed by power from a motor that is driven to rotate in response to an input of a drive pulse, and the line thermal head. A computer that controls a thermal printer that includes a plurality of drive units that respectively drive a plurality of blocks that are units obtained by dividing each of the heating elements of the head, and that collectively drives each of the blocks according to a printing rate In the case of the collective driving, the energization of each heating element by each driving unit for each ON period of the driving pulse is performed. In the case of the divided drive, which is repeated a plurality of times, each of the heating elements by each of the drive units for each ON period of the drive pulse That to function energized as printing control unit for once, characterized in that.

  According to the present invention, in the collective driving applied when the printing rate is low, the control of repeating energization a plurality of times does not become complicated, so each heating element by each driving unit for each ON period of the driving pulse. By repeating the energization for a plurality of times, it is possible to suppress a phenomenon in which a printed character or the like is doubled or a white line is generated, and it is possible to maintain the minimum required image quality while increasing the printing speed. On the other hand, in the divided drive applied when the printing rate is high, it is necessary to drive one line by energizing each heating element by each drive unit once for each ON period of the drive pulse. By keeping the time to a minimum, the speed can be prevented from abruptly decreasing, and the load on the CPU can be reduced. Therefore, it is possible to prevent a decrease in printing performance.

FIG. 1 is a side view schematically showing a label printer according to an embodiment of the present invention. FIG. 2 is a block diagram showing an electrical connection of each part of the label printer. FIG. 3 is a block diagram mainly showing a line thermal head and a head controller. FIG. 4 is a circuit diagram showing the configuration of the drive IC. FIG. 5 is a timing chart showing the operation for each drive IC. FIG. 6 is a timing chart showing the operation when the drive ICs are collectively driven. FIG. 7 is a timing chart showing an operation when each drive IC is dividedly driven. FIG. 8 is a flowchart showing a flow of pattern change processing of the divided drive block. FIG. 9 is an explanatory diagram schematically showing the creation of the phase table. FIG. 10 is a timing chart showing the operation when the collective drive is switched to the three-part drive.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Exemplary embodiments of a thermal printer according to the present invention are explained in detail below with reference to the accompanying drawings. This embodiment is an example applied to a label printer.

  FIG. 1 is a side view schematically showing a label printer 1 according to an embodiment of the present invention. A paper holding unit 3 that holds the continuous paper 2 that is a recording paper is provided outside the housing 4. The label printer 1 according to the present embodiment draws the continuous paper 2 held by the paper holding unit 3 into the housing 4, and the printing mechanism 5 housed in the housing 4 with respect to the drawn continuous paper 2. Print out the prescribed items. In the present embodiment, as the continuous paper 2, label paper or tag paper in the form of roll paper wound in a roll shape is used.

  Inside the housing 4, a paper passage path 8 is formed from the paper feed port 6 to the paper discharge port 7, and the paper holding unit 3 is rotatably held by a pair of paper holding rollers 9 that are rotatable. The continuous paper 2 is guided to be drawn from the paper supply port 6 to the paper passage path 8 and discharged from the paper discharge port 7.

  A printing mechanism 5 is provided in the paper passing path 8 for guiding the continuous paper 2 in this way. The printing mechanism 5 is mainly formed of a rotatable platen roller 11 that is rotationally driven by a stepping motor 10 (see FIG. 2), and a line thermal head 12 that abuts the platen roller 11 via a paper passing path 8. ing. The line thermal head 12 is held by a head holding plate 14 rotatably supported by a support shaft 13 arranged in parallel with the platen roller 11, and this head holding plate 14 is supported by a line thermal head by a spring (not shown). 12 is urged in a direction to be pressed against the platen roller 11.

  Here, as a form of issuing the printed continuous paper 2 by the printing mechanism 5, the label printer 1 according to the present embodiment uses the label peeling plate 15 arranged at the position immediately downstream of the printing mechanism 5 in the paper passing path 8. Peeling issuance for peeling and issuing labels from the mount, continuous issuing for issuing the continuous paper 2 as it is, and cutting the mount for each label using the cutter unit 16, or issuing labels, It is possible to select three types of issuance modes: cut issuance in which continuous paper is cut and issued in predetermined units. Here, description of the structure and control for that is omitted.

  FIG. 2 is a block diagram showing an electrical connection of each part of the label printer 1. Each part of the stepping motor 10 and the line thermal head 12 for rotationally driving the platen roller 11 is driven and controlled by a microcomputer 18 constituted by a CPU 17 and the like. In other words, a CPU 17 is provided for executing various arithmetic processes and controlling each part in a centralized manner. In this CPU 17, a ROM 19 that stores fixed data in a fixed manner and a RAM 20 that stores variable data in a rewritable manner are connected to the system bus 21. Connected through. A control program is stored in the ROM 19, and the microcomputer 18 executes various processes according to the control program stored in the ROM 19 while using the RAM 20 as a work area.

  In the present embodiment, a motor driver 22 for driving and controlling the stepping motor 10 for rotationally driving the platen roller 11 as a part that is driven and controlled by the microcomputer 18 for the printing operation in the printing mechanism 5, and a line A head controller 40 that is a print control unit that controls the thermal head 12 is provided. The motor driver 22 and the head controller 40 are connected to the CPU 17 via the system bus 21.

  In addition, since the label printer 1 of the present embodiment employs a line-type printing method, printing in the main scanning direction is performed by a large number of heating elements 24 (see FIG. 4) that the line thermal head 12 includes in a line shape. Printing is performed in the sub-scanning direction by moving the continuous paper 2 with respect to the line thermal head 12 generated by the conveyance of the continuous paper 2. Therefore, it is necessary to detect the conveyance timing or the like of the continuous paper 2 for printing in the sub-scanning direction. In the present embodiment, two types of transmission sensor 25 and reflection sensor 26 are used for such detection. A sensor unit 27 including these sensors is arranged in the sheet passing path 8. The transmissive sensor 25 and the reflective sensor 26 are connected to the system bus 21 via an I / O port 28. Here, the transmission type sensor 25 is a sensor that detects a mount portion between labels in the label paper used as the continuous paper 2, and the reflection type sensor 26 detects a position detection mark printed on the tag paper. Sensor.

  Further, in the label printer 1 according to the present embodiment, print data transferred from an external device is fetched from the interface 29, and the print data fetched via the interface 29 is converted into image data and developed in the image memory 30. The CPU 17 outputs data for each line from the image data obtained by converting the received print data. Therefore, the interface 29 and the image memory 30 are also connected to the CPU 17 via the system bus 21.

  In addition, a thermistor and an AD converter (both not shown) are attached to the head substrate (not shown) of the line thermal head 12, and a detection signal (head temperature information) by the thermistor is digitally converted by the AD converter. It is connected so that it is converted into and taken into the CPU 17.

  Next, the line thermal head 12 and the head controller 40 will be described in detail. 3 is a block diagram mainly showing the line thermal head 12 and the head controller 40, FIG. 4 is a circuit diagram showing the configuration of the drive IC, and FIG. 5 is a timing chart showing the operation of each drive IC.

  The line thermal head 12 is selective to the heating elements 24 (24-1 to 24-n) (see FIG. 4) arranged in rows that generate heat when energized by a large number (for example, 432). It is configured to be able to apply 24V from a power supply circuit (not shown). As shown in FIG. 3, the line thermal head 12 includes a plurality of drive ICs 51 to 53 as drive units. In this way, by providing a plurality of drive ICs 51 to 53 that respectively drive a plurality of blocks that are units obtained by dividing each heating element 24 of the line thermal head 12, printing of each heating element 24-1 to 24-n is performed. It is possible to shift the timing.

  The head controller 40 is a print control unit that controls the line thermal head 12. As shown in FIG. 3, the head controller 40 includes a block data dividing circuit 41, ON dot number counters 42 to 44, a first addition circuit 45, a second addition circuit 46, a total addition circuit 47, a strobe controller. 48.

  As shown in FIG. 4, each of the drive ICs 51 to 53 includes a plurality of transistors that function as switching transistors corresponding to the respective heat generating elements 24 as a switch circuit 33 for selectively applying a voltage to the heat generating elements 24. 31 (31-1 to 31-n). The bases for controlling on / off of each transistor 31 are connected to AND gates 32 (32-1 to 32-n), respectively, so that output signals from these AND gates 32 are inputted. It has become.

  The line thermal head 12 is provided with a shift register 34 composed of a D-type flip-flop circuit (FF circuit) that operates using the input clock signal CLK as a reference clock. The shift register 34 is configured as a 144-bit register, and the 432 heating elements are divided into three and allocated to the drive ICs 51 to 53. Since the print data is input in parallel to the shift registers 34 of the drive ICs 51 to 53, the input of the print data becomes faster.

  As shown in FIG. 3, the block data division circuit 41 of the head controller 40 converts the print data input from the CPU 17 into print data for each block corresponding to the heating elements 24 applied to the drive ICs 51 to 53 of the line thermal head 12. DAT1, DAT2, DAT3) and output to the shift register 34 of each drive IC 51-53.

  Further, the ON dot number counters 42 to 44 of the head controller 40 are shown in FIG. As shown, the number of heating elements 1 in the data line (the number of ON dots) is counted in synchronization with the clock. When the counts in the ON dot number counters 42 and 43 are respectively input, the first addition circuit 45 calculates the count result of the ON dot number obtained by adding the respective counts. Further, when the counts in the ON dot number counters 43 and 44 are respectively input, the second addition circuit 46 calculates the count result of the ON dot number obtained by adding the respective counts. Further, when the counts in the ON dot number counters 42 to 44 are respectively input, the total addition circuit 47 calculates the count result of the ON dot number obtained by adding the counts of the ON dot numbers of all three blocks. Count results calculated by the addition circuits of the first addition circuit 45, the second addition circuit 46, and the total addition circuit 47 are input to the strobe controller 48.

  The strobe controller 48 controls the division drive pattern of the blocks corresponding to the heating elements 24 applied to the drive ICs 51 to 53 of the line thermal head 12 according to the counting result of each adder circuit. Block division drive pattern change processing executed by the strobe controller 48 will be described later.

  Print data (DAT1, DAT2, DAT3) subjected to history processing (description is omitted) by the head controller 40 is serially input to the shift register 34 of each drive IC 51-53 for each line of the line thermal head 12. It is comprised so that. The print data constituting one line serially input to each shift register 34 of each of the drive ICs 51 to 53 is configured to be output in parallel to the latch circuit 35. Each latch circuit 35 is configured to input parallel print data to one input terminal of the AND gate 32 in response to the input of the data latch signal LATCH (see FIG. 4).

  On the other hand, the strobe signal STB (STB1, STB2, STB3) is generated by the head controller 40 and input from the CPU 17 to the other input terminal of the AND gate 32. As a result, an output signal is generated from the AND gate 32 and output to the base of the transistor 31. Thus, a voltage is applied to the corresponding heat generating element 24, and the heat generating element 24 is driven to generate heat.

  Next, the divided drive block pattern changing process executed by the strobe controller 48 will be described in detail. First, a method of determining a block division drive pattern will be described.

  For example, in the label printer 1 of the present embodiment, when the counting result in the total adder circuit 47 is “144 dots or less”, that is, when the printing rate is low, the strobe controller 48 drives the drive ICs 51 to 53 in a divided manner. The strobe signals STB (STB1, STB2, STB3) that are simultaneously driven (collectively driven) without being output are output to the drive ICs 51 to 53, thereby increasing the printing speed.

  Here, FIG. 6 is a timing chart showing the operation when the drive ICs 51 to 53 are collectively driven. As shown in FIG. 6, the strobe controller 48 outputs strobe signals STB (STB1, STB2, STB3) simultaneously to the drive ICs 51-53. In addition, as shown in FIG. 6, the strobe controller 48 basically energizes the heating element 24 by the drive ICs 51 to 53 when the drive ICs 51 to 53 are collectively driven. Repeated twice.

  On the other hand, when the counting result in the total adding circuit 47 is “144 dots or more”, that is, when the printing rate is high, the strobe controller 48 drives the drive ICs 51 to 53 separately (three-division drive). By outputting the STB (STB1, STB2, STB3) to each of the drive ICs 51 to 53, it is possible to avoid simultaneously using the power supply in each of the drive ICs 51 to 53.

  Here, FIG. 7 is a timing chart showing the operation when the drive ICs 51 to 53 are dividedly driven. As shown in FIG. 7, the strobe controller 48 outputs a strobe signal STB (STB1) to the drive IC 51, and delays the strobe signal STB (STB2) for the drive IC 52 from the strobe signal STB (STB1) for the drive IC 51. The strobe signal STB (STB3) for the drive IC 53 is output after being delayed from the strobe signal STB (STB2) for the drive IC 52.

  FIG. 8 is a flowchart showing the flow of the divided drive block pattern changing process executed for each line by the strobe controller 48.

  As shown in FIG. 8, the strobe controller 48 first determines a block division drive pattern according to the counting result of each adder circuit (step S1). In this embodiment, the drive ICs 51 to 53 are collectively driven or the drive ICs 51 to 53 are separately driven (three-division drive).

  In the subsequent step S2, it is determined whether or not there is a previous print dot and a current print dot, that is, a first dot print.

  If it is first dot printing (Yes in step S2), the temperature is corrected (−5 ° C.) (step S3), and the process proceeds to step S4. The reason for correcting the temperature (−5 ° C.) in the case of the first dot printing is that the line thermal head 12 is cooled during the first dot printing. This is because it is necessary to increase the amount of energy (increase the strobe length).

  On the other hand, if the first dot is not printed (No in step S2), the process proceeds to step S4.

  In the subsequent step S4, it is determined whether or not the number of divisions has increased from the previous line for the block division drive pattern (collective drive or three-part drive) determined in step S1. When the number of divisions increases from the previous line, that is, when the collective drive is changed to the three-division drive (Yes in step S4), the motor step number is updated (step S5), and the process proceeds to step S6. On the other hand, if the number of divisions has not increased from the previous line (No in step S4), the process proceeds directly to step S6. Such control is performed for the following reason. When changing from collective driving to three-division driving, it is necessary to lengthen the motor cycle for three-division driving. At this time, in the printing control by the CPU, the energization time is changed according to the motor cycle of the previous line, so the motor cycle of the collective drive is short, and the energization time is corrected based on the time of the motor cycle. The three-division drive needs to have a longer energization time than the collective drive. However, if a short motor cycle is used, the three-division drive is regarded as a collective drive and the energization time originally required for the three-division drive cannot be secured. Therefore, the motor step number is updated in step S5 so that the energization time can be corrected in the next three-division drive cycle.

  In step S6, the energization time of the strobe signal STB (STB1, STB2, STB3) is obtained. The energization time is obtained by multiplying the basic energization time obtained from the divided drive pattern (collective drive or 3-split drive), density coefficient (90% to 120%), and temperature determined in step S1 by a period coefficient. Sought by.

  In the subsequent step S7, it is determined whether or not the energizing time of the strobe signal STB (STB1, STB2, STB3) obtained in step S6 exceeds the motor cycle of the stepping motor 10.

  When it is determined that the energization time of the strobe signal obtained in step S6 exceeds the motor cycle (Yes in step S7), the previous motor step number is returned (step S8), and the process proceeds to step S9. On the other hand, when the energization time of the strobe signal obtained in step S6 does not exceed the motor cycle (No in step S7), the process proceeds to step S9 as it is. Here, when it is determined that the energization time of the strobe signal exceeds the motor cycle, the reason for returning to the previous motor step number is as follows. In step S7, during the collective driving, the pulse is divided into two as described later and hit twice. However, as described above, in order to correct the energization time according to the previous motor cycle, such an operation is performed during the slow UP. If the process is performed, the energization time may exceed the motor cycle. At that time, if the same motor cycle is used, the energization time does not exceed the motor cycle, and thus such processing is performed.

  In step S9, the current data (block division drive pattern (collective drive or three-part drive), strobe schedule, total number of strobe dots, etc.) is stored.

In step S10, a phase table is created and the process ends. Specifically, the phase table is as shown in FIG.
(1) Collective drive When T1 <S1 (T1: Predetermined time, S1: Strobe signal energization time)
The energization of the heating element 24 by each of the drive ICs 51 to 53 for each ON period of the motor drive pulse is repeated twice.
In the case of T1 ≧ S1, energization of the heating element 24 by each of the drive ICs 51 to 53 is performed once for each ON period of the motor drive pulse.
(2) In the case of three-division drive The energization of the heat generating element 24 by each of the drive ICs 51 to 53 is performed once for each ON period of the motor drive pulse.

  As described above, when T1 ≧ S1, the energization of the heating element 24 by each of the drive ICs 51 to 53 is performed once because the strobe signal energization time S1 is shorter than the predetermined time T1. This is because interrupt processing such as issue processing and motor phase switching processing may not be in time.

Table 1 is a table showing measured values in the case of collective driving at a temperature of 80 ° C. As shown in Table 1, when the print density is lowered by an operator or the like, the energization time S1 of the strobe signal becomes shorter than the processing time T1 of the motor, and the energization of the heating elements 24 by the drive ICs 51 to 53 is performed. It turns out that it is once.

  FIG. 10 is a timing chart showing the operation when the collective drive is switched to the three-part drive. As shown in FIG. 10, in the collective driving, the energization of the heat generating element 24 by each of the drive ICs 51 to 53 is repeated twice for each ON period of the motor driving pulse. In the three-division drive, the energization of the heat generating element 24 by the drive ICs 51 to 53 is performed once for each ON period of the motor drive pulse.

  Thus, according to the present embodiment, in the collective driving applied when the printing rate is low, energization is performed on the condition that the strobe signal has a width that falls within a half cycle of the motor driving pulse. Since the control that is repeated once is not complicated, the energization of the heating element 24 by each of the drive ICs 51 to 53 for each ON period of the motor drive pulse is repeated twice, so that a double or white line is generated in the printed character or the like. The phenomenon can be suppressed, and the necessary minimum image quality can be maintained while increasing the printing speed. On the other hand, in the three-division drive applied when the printing rate is high, the drive ICs 51 to 53 are energized once by the drive ICs 51 to 53 for each ON period of the motor drive pulse to drive one line. By minimizing the time required for printing, it is possible to prevent the speed from abruptly decreasing and to reduce the load on the CPU, thereby preventing a decrease in printing performance.

  In the present embodiment, the strobe controller 48 of the head controller 40 executes the block division drive pattern change process. However, the present invention is not limited to this, and the CPU 17 reads a program previously incorporated in the ROM 19. The module having the same function as that of the strobe controller 48 is loaded on the RAM 20 and the module having the same function as that of the strobe controller 48 is generated on the RAM 20. It may be executed. Such a program may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. Further, such a program may be provided or distributed via a network such as the Internet.

DESCRIPTION OF SYMBOLS 1 Thermal printer 2 Recording paper 10 Motor 12 Line thermal head 24 Heating element 40 Print control part 51-53 Drive part

Japanese Patent Laid-Open No. 11-286131

Claims (6)

A motor that rotates in response to an input of a drive pulse;
A plurality of heating elements are arranged in a line, and a line thermal head that prints on a recording sheet conveyed by power from the motor by selective heat generation of each heating element;
A plurality of drive units that respectively drive a plurality of blocks that are units obtained by dividing the heat generating elements of the line thermal head;
Depending on the printing rate, the drive pattern is changed to collective drive for collectively driving the respective blocks and divided drive for dividing and driving the respective blocks, and in the case of the collective drive, the drive pulse is turned on once. The energization of the heating elements by the driving units for each period is repeated a plurality of times, and in the case of the divided driving, the energization of the heating elements by the driving units for each ON period of the drive pulse is performed once. A print control unit and
A thermal printer comprising: If the energization time for each of the heating elements is shorter than a predetermined time, the printing control unit may perform the driving for each ON period of the driving pulse even in the collective driving. Energizing each heating element by the unit once,
The thermal printer according to claim 1. In the case of first dot printing, the print control unit sets temperature information used for calculating the energization time for each of the heating elements to a temperature lower than the actual temperature.
The thermal printer according to claim 1 or 2, characterized in that. A line thermal head that prints by selective heat generation of each heating element on a recording sheet conveyed by power from a motor that rotates in response to an input of a drive pulse, and each heating element of the line thermal head is divided A computer that controls the thermal printer, and a plurality of drive units that respectively drive a plurality of blocks that are unit units
Depending on the printing rate, the drive pattern is changed to collective drive for collectively driving the respective blocks and divided drive for dividing and driving the respective blocks, and in the case of the collective drive, the drive pulse is turned on once. The energization of the heating elements by the driving units for each period is repeated a plurality of times, and in the case of the divided driving, the energization of the heating elements by the driving units for each ON period of the drive pulse is performed once. Function as a print control unit
A program characterized by that. If the energization time for each of the heating elements is shorter than a predetermined time, the print control unit may perform the driving for each ON period of the driving pulse even in the collective driving. Energizing each heating element by the unit once,
The program according to claim 4. In the case of first dot printing, the print control unit sets temperature information used for calculating the energization time for each of the heating elements to a temperature lower than the actual temperature.
6. The program according to claim 4 or 5, characterized in that:

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