JP2013010200A - Thermal printer, and printing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal printer high in printing quality even when the environmental temperature changes.SOLUTION: This thermal printer includes: a thermal head including a plurality of heating elements; a temperature sensor for measuring temperature; an application energy table for obtaining application energy to the heating elements in accordance with the temperature measured by the temperature sensor; a history table for storing a current-carrying pattern for determining whether a first pulse which is previously carried to the heating element and of which the current-carrying time is determined, when forming a dot, in accordance with printing conditions of several dots immediately before the dot, a pause pulse carried when forming a dot immediately after the dot, an adjustment pulse and a preheating pulse are carried in accordance with formation conditions of the several dots immediately before the dot and the dot immediately after it; and a head control part for carrying current to the heating elements by application energy in accordance with the application energy obtained from the application table with a current-carrying pattern in accordance with the formation conditions of the several dots immediately before the dot and the dot immediately after it.

Description

  Embodiments described herein relate generally to a thermal printer that prints on a print medium using a thermal head and a printing method of the thermal printer.

  In general, a thermal printer using a thermal head generates heat by energizing each heating element of the thermal head, and the thermal paper is colored by the heat, or the ink of the ink ribbon is transferred to the paper for printing. . When the heating element of the thermal head is energized for printing, the generated heat is stored. For this reason, a dot that adjusts the energization time to be applied to the heat generating element depending on whether or not the dot to be energized is used for printing the last several dots, that is, whether or not it is energized is known. . This is called history control.

  History control is performed so that the heating element does not overheat in the case of printing with several dots just before, and the heating element has sufficient heat when several dots are not energized continuously. From the past energization state of the body, the energization time to the heating element when forming one dot is lengthened or shortened.

  In addition, there is a known printer that energizes the thermal head to such an extent that dots are not formed on the paper so that the temperature of the heat generating element is not excessively cooled when a plurality of dots have not been printed in the past.

JP 05-77472 A Japanese Patent Laid-Open No. 2003-154697

  However, since the temperature rise of the heating elements is affected by the environmental temperature, it is necessary to determine the energization control for each heating element in consideration of the environmental temperature. Of course, there have been controls that have taken environmental temperature into account, but control according to changes in temperature is uniform in each temperature range, and energization control according to temperature is not always appropriate. This may affect print quality.

  Therefore, in this embodiment, a thermal head having a plurality of heating elements, a temperature sensor for measuring temperature, and an applied energy table for obtaining energy applied to the heating element according to the temperature measured by the temperature sensor The first pulse whose energization time is determined according to the printing state of several dots immediately before the dot when forming a dot energized to the heating element, and energizing when forming a dot immediately after the dot. A history table that stores an energization pattern indicating whether or not the pause pulse, the adjustment pulse, and the preheating pulse are energized according to the formation state of the dots immediately before and after the dot, and the dots immediately before and after the dot. With the energization pattern according to the dot formation state, the applied energy according to the applied energy obtained from the application table And a thermal printer comprising a head control unit for energizing the serial heating element.

FIG. 2 is a block diagram illustrating a hardware configuration of the thermal printer according to the present embodiment. FIG. 2 is a schematic diagram of a thermal head and a head control unit of the printer. The figure which shows the energization pulse used when this printer prints. The figure which shows the energization time of the 1st pulse and 3 dot pulse corresponding to environmental temperature. The figure which shows the ratio of the pause pulse in 3 dot pulses. The figure which shows the printing pattern in embodiment. The figure which shows the energization time of each pulse in each environmental temperature. The figure which shows electricity supply when environmental temperature is 10 degree | times. The figure which shows electricity supply when environmental temperature is 20 degree | times. The figure which shows electricity supply when environmental temperature is 30 degree | times.

  Hereinafter, embodiments of a printer using a thermal head will be described with reference to the drawings.

  In the printer 1 of this embodiment, a ROM 4, a RAM 5, a communication interface (communication I / F) 6, a head controller 7, a motor controller 8, and a temperature sensor 9 are connected to a CPU 2 via a bus line 3.

  The ROM 4 stores a program executed by the printer and various tables described later. Various tables can be stored in a nonvolatile memory such as a flash memory. The RAM 5 stores print data sent from the external terminal 10 connected to the communication I / F 6 and forms a work area necessary for the CPU 2 to operate. The communication I / F 6 is for connecting to the external terminal 10. A thermal head 11 is connected to the head controller 7 and controls energization of the thermal head 11. A motor 12 is connected to the motor control unit 8. The motor 12 is a stepping motor, and is controlled by the motor control unit 8 to rotate the platen roller and convey the paper. The temperature sensor 9 detects the ambient temperature around the printer 1. Although not described in this embodiment, the thermal printer 1 that transfers the ink ribbon ink onto the paper by the thermal head 11 and prints it is further provided with a control mechanism for winding the ink ribbon.

  The ROM 4 stores an applied energy table 13 and a history setting table 14. The applied energy table 13 is for determining energy to be supplied to the heating element 20 of the thermal head 11 mainly according to the environmental temperature.

  The history setting table 14 is used to determine a print pattern for energizing the heating element 20 to form a certain dot in accordance with the history of two dots generated immediately before the heating element 20 used to form a certain dot. It is. Here, the history is data in which the data of the previous two dots immediately before the dot to be printed and the previous two dots are generated (formed dots) among the bitmap data developed in the print buffer for printing. It is information on whether or not.

  Next, the thermal head 11 and the head controller 7 will be described. In the thermal head 11, for example, 305 heating elements 20 (about 12 / mm) per inch are arranged in a line in the width direction of the paper for a length of 4 inches. The heating element 20 has a resistance that generates heat when energized. A predetermined voltage Vcc is applied to one end of the heating element 20. The other end of the heating element 20 is connected to the collector of the transistor 21 in the head controller 7. The emitter of the transistor 21 is grounded. The output of the AND circuit 22 is connected to the base of the transistor 21. One of the inputs of the AND circuit 22 is connected to a strobe signal. The strobe signal is turned on only for the time when the heating element 20 is energized. The other input of the AND circuit 22 is connected to the latch circuit 23. When a latch signal is input, the latch circuit 23 latches and holds data in the shift register 24 connected to the latch circuit 23. The shift register 24 inputs serial data input from the data signal in synchronization with the clock signal. The head controller includes a transistor 21, an AND circuit 22, a latch circuit 23, and a shift register 24. If there is data in the latch circuit 23, the heating element 20 is energized while the strobe signal is applied.

  The energization to the thermal head 11 in this embodiment will be described. In this embodiment, when the heating element 20 is energized, the history of whether or not the past two dots of the heating element 20 have been energized is referred to, and the next dot to be printed by the heating element The case where the energization time to the thermal head is determined will be described with reference to whether or not energization is performed. A voltage pulse (energization pulse) for energizing the thermal head to form one dot by the thermal head is roughly composed of four pulses: a first pulse W, a pause pulse X, an adjustment pulse Y, and a preheating pulse Z. Further, the first pulse W, the pause pulse X, the adjustment pulse Y, and the preheating pulse Z are combined as a whole pulse, and the pause pulse X, the adjustment pulse Y, and the preheating pulse Z are combined into a 3-dot pulse.

  The first pulse W is a pulse that is energized when printing is performed using either two of the previous two dots or one of the dots. When the previous two dots are printed, the first pulse has a length (energization time) determined according to the environmental temperature as in the applied energy table shown in FIG. Although not described in detail in this embodiment, when any of the previous two dots is energized, the first pulse is appropriately divided according to the pattern and energized to the heating element.

  The 3-dot pulse is always energized when the dot is formed and the next dot is also formed. As shown in FIG. 4, the 3-dot pulse has a length (energization time) determined according to the environmental temperature. The pause pulse X is for shortening the energization time when the next dot is not printed. For example, a phenomenon such as a so-called tail that occurs at the end of a character occurs, but the occurrence of this tailing is prevented by shortening the energization time.

  By the way, a printing cycle in which energization time of all pulses for giving energy necessary for calculation to form a certain dot, that is, the total energization time of the first pulse and the 3-dot pulse shown in FIG. 4 can form one dot. Is longer than the printing cycle and the energization time of all pulses is the same, or the first pulse W is adjusted so that the energization time of all pulses is shortened, the energization of all pulses after correction is performed. Time. That is, a value obtained by subtracting the difference between the energization time of all the pulses before correction and the printing cycle from the first pulse W is the first correction pulse Wz. In this case, the difference between all the pulses and the first pulse W is defined as a preheating pulse Z. The preheating pulse is for energizing the dots in accordance with the outside air temperature when energizing the next dot without energizing the heating element 20 continuously for two dots. That is, when sufficient thermal energy cannot be given to the dots to be printed next in one printing cycle, the heating element 20 is energized using the printing cycle in which the previous dot is not formed, and the next printing cycle is started. Appropriate thermal energy is applied along with the energization time.

  For the corresponding heating element 20, when the previous two dots are printed, the dot is printed with a three-dot pulse when the next dot is printed, and with the pause pulse X when the next dot is not printed. Without using the adjustment pulse Y and the preheating pulse Z. The adjustment pulse is a value obtained by subtracting the preheating pulse Z and the pause pulse X from the 3-dot pulse.

When these are expressed in mathematical formulas, preheating pulse Z = all pulses−printing cycle adjustment pulse Y = 3 dot pulses− (pause pulse X + preheating pulse Z)
The first correction pulse Wz when all the pulses are longer than the printing cycle is
First correction pulse Wz = first pulse W−preheating pulse Z
It becomes.

  The pause pulse is a ratio (reduction rate) for each temperature shown in FIG.

Pause pulse X = 3 dot pulse × reduction rate In this embodiment, 13 microseconds are required for data processing related to energization in circuit design, so the first pulse W, pause pulse X, adjustment pulse Y, preheating pulse Z If each value is 13 microseconds or less, it is set to 13 microseconds. However, this value can be appropriately changed according to the data processing capability of the printer. Here, the strobe signal is given in common to the plurality of heating elements 20 as the energization time of these pulses.

  Next, when the thermal head resolution is 305 dots / inch and the printing speed is 12 inches / second, the dots shown in FIG. 6 when the environmental temperature (atmosphere temperature) is 10 degrees, 20 degrees, and 30 degrees are shown in FIG. A specific example in which the heating element 20 is energized will be described. Incidentally, at this time, since the printer performs printing of 305 × 12 = 3660 dots per second, the printing cycle is 273 microseconds, and this 273 microseconds is the maximum time that can be used to form one dot. Become.

Example 1 When the environmental temperature is 10 degrees. From FIG. 4, the first pulse W is 210 microseconds, the 3-dot pulse is 110 microseconds, and the reduction rate is 18% from FIG. Second. In addition, since the total pulse, which is the sum of the first pulse W and the 3-dot pulse, is 320 microseconds and is longer than the printing cycle 273 microseconds, the preheating pulse X is 47 microseconds and the first correction pulse Wz is 163 microseconds. . The adjustment pulse Y is 44 microseconds (= 110− (19 + 47)).

  By the way, in this example, since the 3-dot pulse is 110 microseconds and the reduction rate is 18%, the calculation is 19.8 microseconds, but the fractional part is rounded down to 19 microseconds. However, the number after the decimal point may be rounded up or rounded off according to the required level of the product.

Example 2 When the environmental temperature is 20 degrees From FIG. 4, the first pulse W is 180 microseconds, the three-dot pulse is 100 microseconds, and the reduction rate is 25% from FIG. Second. Further, the total pulse that is the sum of the first pulse W and the 3-dot pulse is 280 microseconds and the printing cycle is 273 microseconds. Therefore, the preheating pulse X is calculated to be 7 microseconds, but it is 13 microseconds or less because it is 13 microseconds or less. To do. As a result, the first correction pulse Wz is 167 microseconds. The adjustment pulse Y is 62 microseconds (= 100− (25 + 13)).

  Thus, Wz is 167 microseconds, pause pulse is 25 microseconds, adjustment pulse is 62 microseconds, preheating pulse is 13 microseconds, and all pulses are 267 microseconds.

Example 3 When the environmental temperature is 30 degrees From FIG. 4, the first pulse W is 180 microseconds, the three-dot pulse is 80 microseconds, and the reduction rate is 35% from FIG. Second. It is the difference between the printing cycle and all pulses. The preheating pulse X is 13 microseconds. The adjustment pulse Y is 39 microseconds (= 80− (28 + 13)). The total pulse is 260 microseconds, which is the sum of the first pulse W and the 3-dot pulse.

  Next, energization to the d rows of heating elements when forming dots as shown in FIG. 6 will be described. Columns A to D indicate the respective print field patterns. In the column A, the dots of the a-line, the b-line, and the c-line are printed, then the d-line dot is printed, and the next e-line is not printed. Even when the temperature is 10 degrees, 20 degrees, or 30 degrees, the first pulse is not energized because the previous two dots (b line and c line) are printed. Therefore, whether or not the thermal head 11 is energized is determined by whether or not there is data of the corresponding heating element 20 input to the shift register 24. That is, even if the strobe signal is input, the AND circuit 22 takes the AND of the strobe signal and the latch circuit 23. Therefore, the heating element 20 is energized if there is data for energizing the A column, and not energized if there is no data. . Next, for the 3-dot pulse, the adjustment pulse Y and the preheating pulse Z are energized without energizing the pause pulse X because the next e-line is not printed.

  A description will be given of the print pattern of the B row. In the B column, an a line, a b line, and a c line dot are printed, then a d line dot is printed, and the next e line dot is also printed. Regardless of whether the temperature is 10 degrees, 20 degrees, or 30 degrees, the first pulse is not energized because the previous two dots (b line and c line) are printed. Next, in order to print the next e-line for the 3-dot pulse, the rest pulse X is energized and the adjustment pulse Y and the preheat pulse Z are energized, unlike the A column. That is, the entire 3-dot pulse is energized.

  A description will be given of the print pattern of the C column. In the column B, an a line, a b line, a c line, and a d line are printed, and the next e line is printed. When the temperature is 30 degrees, all pulses (260 microseconds) with sufficient thermal energy can be applied to the paper in one printing cycle (273 microseconds), so that no energization is performed in line d. On the other hand, when the temperature is 10 ° C. or 20 ° C., sufficient heat energy cannot be applied within one printing cycle of the e-line, so it is necessary to energize the preheating pal Z in the d-line. The energization by the preheating pulse Z in the d row and the energization of all the pulses in the e row are combined to provide energy suitable for dot formation in the e row. For this reason, the preheating pulse Z is energized in the d row, and in the e row, Wz obtained by subtracting the preheating pulse Z from the energizing time of the first pulse obtained from the table is energized as the first pulse.

  The print pattern of the D column is an example in which the next d line and e line are printed without printing a line, b line, and c line. In this case, although preheating is given at 10 degrees and 20 degrees in the c line, the first correction pulse Wx is energized because the previous 2 dots are not printed dots in the d line. Further, in order to print the next e-line, the pause pulse X is energized, and the adjustment pulse Y and the preheating pulse Z are also energized. At 30 degrees, since it is not necessary to correct the first pulse W, the first pulse W, the pause pulse X, the adjustment pulse U, and the preheating pulse Z are all energized.

  FIG. 7 shows the energization time of each pulse in the d row for the A column to the D column for each of the temperatures of 10 degrees, 20 degrees, and 30 degrees. The numerical value obtained by adding a Δ mark to the preheating pulse Z indicates that energization is applied to the d line for preheating when the e line is printed. Even if the dots that are not printed are energized, the temperature rise is not sufficient to develop the color of the paper or transfer the ink on the ink ribbon, and therefore, printing is not performed on line d.

  8, 9, and 10 show energization patterns of c-rows, d-rows, and e-rows in columns A, B, C, and D when the environmental temperature is 10 degrees, 20 degrees, and 30 degrees. . Here, the pause pulse X in the B column, C column, and D column e row is energized when dots are further printed on the next row, and is not energized when dots are not formed on the next row. For this reason, (X) and parentheses are used in the drawings. Similarly, in the B column, the C column, and the D column e row, in order to form the second continuous dot, the first pulse is the first energization pulse W when two dots are not continuously formed. The energization pulse W ′ is shorter than the energization time.

  In FIG. 9, the energization of the first pulse W is not started after applying the preheating pulse Z in the C row and the D row (6 microseconds in this example), and then the energization of the first pulse W is started. Since the body 20 is to be warmed, even if the first pulse W is energized subsequent to the energization of the preheating pulse Z, the energization time of the necessary energization pulse does not become too large, and the print quality is deteriorated. There is no such thing.

  When the thermal printer 1 receives print data from an external terminal 10 connected to the outside, the thermal printer 1 analyzes the received data and expands the print data in a print buffer. In addition, at the timing when the print data is received from the external terminal 10, the temperature sensor 9 captures the environmental temperature (the ambient temperature around the printer). Regarding the print quality, the thermal head 11 itself can be manufactured with a material that is easy to rise in temperature and is easy to cool, and has a good thermal response. This is because the print quality is affected by the temperature of the recording medium (paper).

  Then, the sheet starts to be conveyed by the motor 12 and energization of the heating element 20 of the thermal head 11 is started. At this time, the length of the energized pulse is set according to the temperature taken in by the temperature sensor 9, and the energized pulse having the set length is given to the resistor 10.

  As described above, in this embodiment, even when printing is performed on the previous two dots, the energized pulse is divided into the pause pulse X, the adjustment pulse Y, and the preheating pulse Z, and is not printed with the next dot. Is not energized with the pause pulse X, and is energized with the preheating pulse Z when sufficient heat energy cannot be applied within one printing cycle when the previous two dots are not energized. Further, an adjustment pulse Y is provided in order to ensure a necessary energization time for printing the dots. For this reason, appropriate electrical energy (energization time) can be given to the heating element in accordance with the environmental temperature, and it becomes possible to achieve high print quality.

  The energization time and the like shown in this embodiment are determined by specific conditions. If the thermal head changes, it is necessary to set conditions according to the thermal head. In some cases, an appropriate energization time is obtained depending on the type of ink ribbon.

  As described above, the embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  1 .. Thermal printer, 7 .. Head control unit, 11 .. Thermal head, 13 .. Applied energy table, 14 .. History setting table, 20 .. Heating element, W .. First pulse, X. Pulse, Y ... Adjust pulse, Z ... Preheat pulse.

Claims (9)

A thermal head having a plurality of heating elements;
A temperature sensor for measuring the temperature;
An applied energy table for obtaining applied energy to the heating element according to the temperature measured by the temperature sensor;
A first pulse whose energization time is determined according to the printing state of several dots immediately before the dot when forming a dot energized to the heating element, and a pause pulse that is energized when forming a dot immediately after the dot A history table for storing an energization pattern as to whether or not the adjustment pulse and the preheating pulse are energized according to the formation state of the dots just before and after the dot,
A thermal printer comprising: a head control unit that energizes the heating element with applied energy corresponding to applied energy obtained from the application table in an energized pattern according to the formation state of the dots just before and after the dots.   2. The thermal printer according to claim 1, wherein the first pulse does not energize the heating element when printing is performed for the immediately preceding two dots when forming the dots.   2. The thermal printer according to claim 1, wherein, when printing is not performed on a dot immediately after the dot, the pause pulse does not energize the heating element in forming the dot.   In the case of forming the next dot without printing on the dot and the previous two dots, the first pulse, pause pulse, adjustment pulse, and preheating pulse, which change depending on the temperature, can be used for forming one dot. 2. The thermal printer according to claim 1, wherein if the total energization time is long, the heating element is energized during the dot printing cycle for a time corresponding to the preheating pulse.   5. The thermal printer according to claim 4, wherein an immediately following dot is formed by using a current pulse of a time obtained by subtracting the current supply time of the preheating pulse from the current supply time of the first pulse at the temperature measured by the temperature sensor as a new first pulse.   When forming the next dot without printing on the dot and the previous two dots, the print cycle that can be used to form one dot and the total energization time of the first pulse, pause pulse, adjustment pulse, and preheat pulse, The printer according to claim 4, wherein the difference is the energization time of the preheating pulse.   When any one of the first pulse to the preheating pulse is shorter than the time for the control unit to perform the process of energizing the heating element, the control unit performs the process of energizing the heating element. 2. The thermal printer according to claim 1, wherein the thermal printer is set to be equal to or longer than the time for performing.   The thermal printer according to claim 1, wherein the applied energy is changed according to a time during which the heating element is energized.   3 dots pulse to energize the dot when printing one dot immediately after the dot that is printed after printing a plurality of dots continuously with one heating element, energize when the next dot is not printed A pause pulse, a preheat pulse for applying preheating in a state where a plurality of dots are not continuously formed, and an adjustment pulse for a time obtained by subtracting the total energization time of the pause pulse and the preheat pulse from the energization time of the 3-dot pulse The printing method of the thermal printer which gives to the said heat generating body divided | segmented into these 3 pulses.

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