JP2003191518A - Controlling method and controller for heater in thermal head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a controller for controlling heat generation of heaters in a thermal head such that printing is performed in an appropriate print time depending on the voltage of a mounted battery. <P>SOLUTION: In a thermal printer mounted with a thermal head 10 arranged with heaters in the main scanning direction, the voltage V of a battery 30 for supplying a current to the thermal head 10 is detected at a battery voltage detecting section 31 when the printer is stated. An upper limit number of heaters capable of generating heat simultaneously is set depending on the voltage V at a control section 20, then number of print pixels included in a line of image data is calculated every time when a line of image data is inputted, and the image data is outputted, as it is, to the thermal head and printed if the number of print pixels does not exceed the upper limit number of heaters. If the number of print pixels exceeds the upper limit number of heaters, the image data is divided into a plurality of pieces of data and printing of one line is performed while being divided into a plurality of times. If the voltage V is large, a large upper limit number of heaters is set and the number of printing times is decreased. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating element control method and control apparatus for a thermal head mounted on a thermal printing apparatus or the like, and more particularly to a heating element arranged in a row on a thermal head using a battery. The present invention relates to a heating element control method and a control device for supplying an electric current.

[0002]

2. Description of the Related Art Conventionally, a thermal head in which a large number of heating elements are arranged in the main scanning direction is used to move a thermal printing paper in the sub-scanning direction while printing based on input image data. 2. Description of the Related Art Development of a small-sized device that is easy to carry, such as a printing device or a heat-sensitive stencil plate making device that makes a plate while moving a stencil sheet, is under development. In these devices, batteries are often used as a power source. On the other hand, when performing thermal printing or stencil plate making, the number of heating elements that generate heat varies depending on the contents of the input image data, so the current supplied to the heating elements also changes significantly. Naturally, the largest current is required to heat all the heating elements. For this reason, even if all the heating elements are heated, if a battery that can supply a sufficient current is mounted, it is inevitable that the battery becomes large.

As a countermeasure against this, there is known a division printing method in which a heating element of a thermal head is divided into a plurality of blocks and printing or plate making is performed by sequentially supplying an electric current to generate heat. By adopting this divisional printing method, the maximum current consumption can be suppressed, and the battery can be downsized, that is, the device can be downsized. However, when the heating element is divided into a plurality of blocks to generate heat, the heating element in the main scanning direction is
In order to generate heat by dividing the image data of the line into multiple times,
There is a problem in that the number of times of heat generation increases and the printing time or plate making time increases. The applicant of the present application, in Japanese Patent Laid-Open No. 2000-6457, sets the upper limit of the number of heating elements that can simultaneously heat the heating elements in advance according to the power source capacity, and the number of heating pixels in one line in the main scanning direction included in the image data, that is, When the number of heating elements that generate heat is less than the upper limit number of heating elements, a thermal printing apparatus that suppresses an increase in printing time is proposed by simultaneously heating the heating elements of a plurality of blocks.

[0004]

On the other hand, the voltage of the battery mounted in the thermal printing apparatus or the stencil plate making apparatus is not always constant and gradually decreases with use. In addition, the battery voltage may decrease even when the environmental temperature decreases. For this reason, the above-mentioned printing device or plate-making device is designed so that printing or plate-making can be performed even if the battery voltage is the lower limit voltage.

FIG. 8 is a graph showing an example of changes with time of the battery voltage and the voltage applied to the heating element in a thermal printing apparatus having a battery-driven thermal head. This thermal head is provided with 12 heating elements. The solid line shows the internal resistance of the battery, and the dotted line shows the battery voltage. The broken lines indicate the voltages applied to all the heating elements mounted on the thermal head, that is, when the 12 heating elements are heated, and the dashed-dotted line indicates the heating elements divided into two parts. That is, when the six heating elements are heated, the voltage applied to each heating element is shown, and the two-dot broken line indicates that each heating element is divided into four heating elements, that is, when three heating elements are heated. It shows the voltage applied to the body.

If the minimum applied voltage to each heating element required to maintain the printing quality is 4.8 volts, the number of printable months when the heating element is not divided is such that the applied voltage is 4.8 volts or more. The number of printable months when the image is divided into two is 7 months, and the number of printable months when the image is divided into four is 8 months.

If the upper limit number of heat generating elements that can generate heat at the same time is set, it is necessary to set the upper limit number of heating elements that enables printing even if the battery voltage drops to the lower limit voltage. That is, for example, if one battery is used for printing for 7 months, the upper limit number of heating elements is designed to be 6, and if printing is required for 8 months, the upper limit number of heating elements is set. Design to be 3. If this printing device
If it is likely to be used in a place with low temperature,
It is also necessary to consider a decrease in battery voltage due to a decrease in temperature. For example, in order to reliably perform printing for 7 months, it is desirable to set the upper limit number of heating elements to a number smaller than 6.

On the other hand, when the upper limit number of heating elements is reduced, if the number of print pixels (the number of heat generating pixels) existing on one main scanning line of the image data is large, the heat generation corresponding to the image data of one main scanning line is generated. Since the number of heat generations for heating the body increases, that is, the number of prints until the printing of one line in the main scanning direction is completed increases, the printing time increases.
In particular, even when the battery voltage is sufficiently high, the heating elements are sequentially heated based on the upper limit number of printable elements when the battery voltage is the lower limit voltage, so that one main scanning line is supported. There is a problem in that the number of times of heat generation is unnecessarily increased, and unnecessary printing time is increased. Further, also in the thermal plate-making device equipped with the battery, even when the battery voltage is sufficiently high, the number of times of heat generation corresponding to one main scanning line is unnecessarily increased, and unnecessary plate-making time is increased. There is a problem of inviting.

In view of the above circumstances, the present invention provides a control method and a control device for controlling heat generation of a heating element of a thermal head, in which heat generation corresponding to image data of one main scanning line is generated in accordance with a mounted battery voltage. An object of the present invention is to provide a control method and a control device capable of appropriately setting the number of times of heat generation for causing a body to generate heat and preventing an unnecessary increase in the number of heat generation.

[0010]

A method for controlling a heating element of a thermal head according to the present invention is a heating element for a thermal head in which a plurality of heating elements are arranged in a main scanning direction based on input image data. The method of controlling the heat generating operation of, wherein the heat generating operation is performed by supplying a current of a battery to the heat generating body, the voltage of the battery is detected, and based on the detected voltage. , The upper limit number of heating elements that is the number of heating elements capable of supplying current at the same time is determined, and the number of heating pixels existing on one main scanning line in the image data is determined. If it is larger than the number of bodies, the image data is divided into a plurality of blocks in which the number of heat generating pixels is equal to or less than the upper limit number of heat generating bodies, and the current is supplied to the heat generating bodies at different timing for each block. Control Characterized in that it.

It should be noted that "the number of heat generating pixels existing on one main scanning line of the image data" means, for example, if the present invention is applied to a thermal printer, on one main scanning line of the image data. If the present invention is applied to a thermal stencil plate making apparatus, it is the number of punching pixels existing on one main scanning line in the image data.

Another heating element control method for a thermal head according to the present invention is based on input image data, and performs a heating operation of the heating element of a thermal head in which a plurality of heating elements are arranged in the main scanning direction. A method of controlling, wherein the heating operation is performed by supplying a current of a battery to the heating element, the voltage of the battery is detected, and the detected voltage is below a predetermined value. In this case, the image data is divided into a plurality of blocks, and control is performed so that current is supplied to the heating element at different timings for each block.

A heating element control device for a thermal head according to the present invention controls a heating operation of the heating element of a thermal head in which a plurality of heating elements are arranged in a main scanning direction based on input image data. In the device, the heating operation is performed by supplying a current of a battery to the heating element, and a battery voltage detecting unit that detects a voltage of the battery, and one main scanning line of the image data. Based on the number of heating pixels calculating the number of heating pixels existing above and the voltage detected by the battery voltage detecting means, an upper limit number of heating elements, which is the number of heating elements capable of simultaneously supplying current, is determined. Comparing the upper limit number of heat generating elements with the number of heat generating pixels, and when the number of heat generating pixels is larger than the upper limit number of heat generating elements, the image data is processed so that the number of heat generating pixels included in one block is higher than the upper limit number of heat generating pixels. It is characterized by including a plurality of blocks so that the number of heating elements is equal to or less than the number of heating elements, and a current supply control means for controlling each block so that current is supplied to the heating elements at different timings. It is a thing.

Another heating element control device for a thermal head according to the present invention controls the heating operation of the heating element of the thermal head in which a plurality of heating elements are arranged in a row in the main scanning direction based on input image data. A device for controlling, wherein the heat generation operation is performed by supplying a current of a battery to the heating element, and battery voltage detection means for detecting the voltage of the battery, and the detected voltage are predetermined. If the value is less than or equal to the value, the image data is divided into a plurality of blocks, and a current supply control means for controlling the current to be supplied to the heating element at different timings for each block is provided. It is a feature.

As the battery voltage detecting means, it is possible to use a means for detecting the voltage of the battery while a motor for moving the thermal paper is connected to the battery as a load. The "thermal paper" is, for example, a thermal printing paper if the thermal head is applied to a thermal printing apparatus, or if the thermal head is applied to a thermal stencil making apparatus, It is a stencil paper.

[0016]

In the method and apparatus for controlling the heating element of the thermal head according to the present invention, the upper limit number of heating elements is determined based on the voltage of the battery mounted and the upper limit number of heating elements is present on one main scanning line of the image data. When the number of heating pixels is larger than the upper limit number of heating elements, the image data is divided into a plurality of blocks such that the number of heating pixels included in each block is equal to or less than the upper limit number of heating elements, and for each block, By controlling the current to be supplied to the heating element at different timings, the number of times of heating for heating the heating element corresponding to the image data for one main scanning line is appropriately adjusted according to the battery voltage installed. It is possible to prevent an unnecessary increase in the number of times of heat generation. Therefore, if the present invention is applied to a thermal printing apparatus, it is possible to perform printing at an appropriate printing time according to the voltage of the battery installed, and further, the operating time of the battery increases, Since printing can be performed even when the battery voltage is low, printing can be performed for a long time using a small battery.

When the present invention is applied to a heat-sensitive stencil plate-making apparatus, plate-making can be carried out for an appropriate plate-making time according to the voltage of the mounted battery, and the battery can be used for a long time. Even if the battery voltage increases and the battery voltage becomes low, plate making can be performed, so that plate making can be performed for a long time using a small battery.

In another method and apparatus for controlling a heating element of a thermal head according to the present invention, when the voltage of the battery mounted is below a predetermined value, the image data is divided into a plurality of blocks. However, by controlling the electric current to be supplied to the heating element at different timing for each block, according to the battery voltage installed,
It is possible to appropriately set the number of times of heat generation for causing the heating element corresponding to the image data of one main scanning line to generate heat, and prevent an unnecessary increase in the number of heat generations. Therefore, if the present invention is applied to a thermal printing device, it is possible to perform printing at an appropriate printing time according to the voltage of the battery installed, and further increase the battery usage time, Since printing can be performed even when the battery voltage is low, printing can be performed for a long time using a small battery. Further, when the present invention is applied to a heat-sensitive stencil plate making apparatus, it is possible to carry out the plate making in an appropriate plate making time according to the voltage of the battery mounted, further increase the use time of the battery, Even when the battery voltage becomes low, plate making can be performed, so that plate making can be performed for a long time using a small battery. Further, the above effects can be obtained with simple control software.

When the battery voltage is measured, if the voltage is detected while the motor for moving the thermal paper is connected to the battery as a load, the battery voltage during actual operation is determined. Close voltages can be measured.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A thermal printing apparatus, which is a first embodiment to which a heating element control method and control apparatus for a thermal head according to the present invention are applied, will be described in detail below with reference to the drawings. First, the configuration of the thermal printing apparatus will be described with reference to FIGS. 1 is a schematic configuration diagram of the thermal printing apparatus, FIG. 2 is a sectional view taken along the line AA of the thermal printing apparatus, and FIG. 3 is a block diagram of a control unit.

This thermal printing apparatus is equipped with a thermal head 10 in which twelve heating elements 11 are arranged in a row in the main scanning direction, and at the time of starting the apparatus, the thermal head 10 is responsive to the voltage of a battery 30 installed therein. When the upper limit number N of heating elements is set and the number of printing pixels K, which is the number of pixels for printing existing on one main scanning line of the image data, is larger than the upper limit number of heating elements, the image data is converted into a plurality of heating data. It is divided into two and printed. The number of print pixels K corresponds to the number of heat generation pixels of the present invention.

As shown in FIG. 1, this thermal printing apparatus has a platen roller 2 for conveying the thermal paper 1, a sub-scanning drive motor 3 for rotationally driving the platen roller 2, and a gear section 4.
And a thermal head 10 that is press-contacted to the platen roller 2 so that it can be contacted and separated from the platen roller 2 by a press-contact mechanism (not shown).
A controller 20 that outputs a control signal to the sub-scanning drive motor 3 and the thermal head 10, and a battery 30 that supplies a drive current to the sub-scanning drive motor 3 and the thermal head 10.
And a battery voltage detector 31 for detecting the voltage of the battery 30.

The sub-scanning drive motor 3 is a step motor. When the sub-scanning drive motor 3 rotates one step, the gear ratio of the gear unit 4 is set so that the platen roller 2 conveys the thermal paper 1 by one pixel pitch. It is set.

The thermal head 10 is a so-called thick film type thermal head. As shown in FIG. 2, twelve lead electrodes 12 are arranged on a substrate 13 at predetermined intervals.
It is provided in a comb shape. One heating element 11 is formed on each lead electrode 12, one end of which is connected to the battery 30,
The other end is connected to a control circuit (not shown).

As shown in FIG. 3, the control section 20 detects the number of print pixels K of the input image data (for one line) in the main scanning direction by a pixel number calculation section 201 and a battery voltage detection section 31. Based on the voltage of the battery 30
The upper limit number of heat generators N, which is the number of heat generators 11 that can supply current at the same time, is set, and this upper limit number of heat generators N is compared with the number of print pixels K, and the number of print pixels K is larger than the upper limit number of heat generators N. In this case, the image data is divided into a plurality of pieces of heat generation data so that the number of print pixels included in one piece of heat generation data is equal to or less than the upper limit number N of heat generating elements, and each heat generation data is sequentially transferred to the thermal head 10. A current supply control unit 2 for outputting to the sub-scanning drive motor 3 a motor drive signal for outputting and printing, and for rotationally driving the platen roller 2 that conveys the thermal paper 1.
02 and.

The current supply control section 202 uses heat generation data as a control signal for selectively heating the heating elements 11 arranged in the main scanning direction, a clock signal, and a register provided in the thermal head 10. A latch signal for setting heat generation data (not shown) (so-called latching) and a strobe signal are output to the thermal head 10 to control current supply to each lead electrode 12 of the thermal head 10. By doing so, the heating operation of each heating element 11 is controlled. In addition to the above control operation, the control unit 20 also controls the operation of the entire apparatus including page breaks and the like.

In the thermal head 10, when the signal product of the heat generation data and the strobe signal latched in the register provided for each lead electrode 12 of the thermal head 10 is on, the lead electrode 12 is supplied to the battery 30 from the battery 30. The current is supplied, and the heating element 11 provided on the lead electrode 12 generates heat, so that actual printing is performed.

With reference to the flow chart shown in FIG. 4, the detailed operation of the thermal printing apparatus will be described, centering on the operation of the control unit 20.

When a switch (not shown) of the thermal printing apparatus is turned on, first in step 101, the sub-scanning drive motor 3 is connected to the battery 30 as a load. However, at this time, the sub-scanning drive motor 3 is not actually driven. In step 102, the battery voltage detection unit 31 detects the voltage V of the battery 30 and inputs it to the control unit 20.

In step 103, the current supply controller 202 of the controller 20 determines whether or not the voltage V of the battery 30 detected in step 102 is less than or equal to a preset reference voltage value VS. In this embodiment, 5.5V is set as the reference voltage value VS. Battery 3
If the voltage V of 0 is equal to or less than the reference voltage value VS = 5.5V, the process proceeds to step 104, where the voltage V of the battery 30 is equal to the reference voltage value V.
If it is larger than S = 5.5V, the process proceeds to step 105.
In step 104, the heating element 1 capable of supplying current simultaneously.
4 is set as the upper limit number N of heating elements, which is the number of 1. In step 105, 7 is set as the upper limit number N of heating elements.

In step 106, image data for one line in the main scanning direction is read. A data map including the number of lines in the sub-operation direction, the total number of lines for one page, and the number of printed pages is attached to the image data for one line. In step 107, the pixel number calculation unit 201 obtains the number of pixels to be printed included in the image data read in step 106, that is, the number of print pixels K that is the number of heating elements 11 to generate heat.

In step 108, the current supply controller 20
2, the upper limit number N of heating elements and the number K of printing pixels are compared. If the number K of printing pixels is less than or equal to the upper limit number N of heating elements, the process proceeds to step 109. If the number K of printing pixels is greater than the upper limit number N of heating elements, the process proceeds to step 110.

In step 109, heat generation data is created from the image data by applying an ON signal to the print pixel portion and an OFF signal to the portion other than the print pixel portion. Step 11
At 0, the image data is divided into a plurality of blocks, and heat generation data is created for each block. First, the image data is divided into a plurality of blocks in which the number of print pixels is equal to or less than the upper limit number of heating elements. When dividing the image data, the division is performed so that the number of print pixels included in each block is as equal as possible. For each block, an ON signal is applied to the print pixels and an OFF signal is applied to the portions other than the print pixels to generate heat generation data.

In step 111, the heat generation data, the clock signal and the latch signal are output to the thermal head 10.
When there are a plurality of heat generation data, one heat generation data is selected and output.

In step 112, a strobe signal is output to the thermal head 10 to heat the heating element 11 to print.

In step 113, it is determined whether or not all the image data for one line, that is, the generated heat data has been output to the thermal head 10. If all the image data has been output, the process proceeds to step 114. If the heat generation data that has not been output remains, the process returns to step 111, and steps 111 to 113 are repeated to output and print the heat generation data.

In step 114, it is determined from the data map attached to the image data whether all the image data of the page currently being printed have been output, that is, whether printing for one page has been completed. If finished, step 11
Go to 6. If not completed, the process proceeds to step 115, the motor drive signal is output to the sub-scanning drive motor 3, the platen roller 2 is driven to rotate by one line, that is, line feed is performed, and the process returns to step 106 to return to the next line. Print.

In step 116, from the data map,
It is determined whether the output of all image data is completed, that is, whether the printing of all pages is completed. If it is finished, the operation is finished. If not, step 117
Then, the procedure advances to step S1, where the next print sheet is placed at the print position, that is, a page break is performed, and the process returns to step 106 to start printing the next page.

Next, in accordance with the above flow chart, FIG.
A printing operation when printing is performed based on image data as shown in FIG. First, the operation when the battery voltage is 5V will be described with reference to FIG.

If the battery voltage V is 5 V, step 10
In 4, the upper limit number of heating elements N is set to 4. At step 104, the first 1 as shown in FIG.
The image data A of the line is read. In step 107, the number of print pixels K = 2 is calculated. In step 108,
Since the number of printed pixels K = 2 is equal to or less than the upper limit number of heating elements N = 4, heat generation data A1 as shown in FIG. 6B is created from the image data A in step 109. Step 111
6 outputs the heat generation data A1, the clock signal shown in FIG. 6C, and the latch signal shown in FIG. 6D, and outputs the strobe signal shown in FIG. To do. The image shown on the leftmost side of FIG. 6G is printed. Since all the heat generation data has been output, the process proceeds from step 113 to step 114. 1
Since printing of pages has not been completed, step 114
6 to step 115, the motor drive signal shown in FIG. 6 (f) is output to drive the sub-scanning drive motor 3 to perform a line feed operation, and the process returns to step 106.

In step 106, the image data B of the next line is read. The number of print pixels K = 6 in step 107
To calculate. In step 108, the number of print pixels K =
6 is larger than the upper limit number of heating elements N = 4, step 11
The process proceeds to 0 and heat generation data is created from the image data B. The number of print pixels included in each heat generation data is the upper limit number of heat generating elements N =
Since the heat generation data is created so that the number of print pixels included in each heat generation data is equal to or less than 4 and the print pixels included in each heat generation data are as equal as possible, the image data B as shown in FIG. Two heat generation data B1 and B as shown in
2 is created. In step 111, the heat generation data B1
A clock signal and a latch signal are output, and a strobe signal is output in step 112 to perform printing. The image described second from the left side in FIG. 6G is printed. Since the heat generation data B2 has not been output yet, the process returns from step 113 to step 111. Step 111
Then, the remaining heat generation data B2 is output and step 1
Printing is performed at 12. The image described third from the left side in FIG. 6G is printed. Since all the heat generation data has been output, step 113 to step 11
Go to 4. Since printing for one page has not been completed, the process proceeds from step 114 to step 115, the sub-scanning drive motor 3 is driven to perform a line feed operation, and the process returns to step 106.

In step 106, the image data C of the next line is read. The number of print pixels K = 1 in step 107
Calculate 2. In step 108, the number of print pixels K
= 12 is larger than the upper limit number of heat generating elements N = 4, the process proceeds to step 110, and heat generation data is created from the image data C. From the image data C, the number of print pixels is 4 each.
Three pieces of heat generation data C1, C2 and C3 are created. Thereafter, the heat generation data C1, C2, and C3 are sequentially printed, the image on the rightmost side of FIG. 6G is printed, and the process proceeds to step 114. If the printing for one page is completed, the process proceeds to step 116. To print the next page, proceed to step 117, perform a page break,
Return to step 106. When printing is completed on this page, the process proceeds from step 116 to end and the operation is completed.

Next, the battery is still new and the battery voltage is 6V.
In the case of, the operation in the case of printing the same image data as shown in FIG. 5 will be described with reference to FIG. 7.

If the battery voltage V is 6 V, step 10
In 4, the upper limit number of heating elements N is set to 7. In step 104, the image data A of the first one line as shown in FIG. 7A is read. In step 107, the number of print pixels K = 2 is calculated. In step 108, the number of print pixels K = 2 is equal to or less than the upper limit number of heat generating elements N = 7.
In step 109, the heat generation data A1 shown in FIG. 7B is created from the image data A. In step 111, the heat generation data A1, the clock signal shown in FIG. 7 (c), and the latch signal shown in FIG. 7 (d) are output, and in step 112, the strobe signal shown in FIG. 7 (e) is output. And print. The image described on the leftmost side of FIG. 7G is printed. Since all the heat generation data is output,
The process proceeds from step 113 to step 114. Since printing of one page has not been completed, the process proceeds from step 114 to step 115, the motor drive signal shown in FIG. 7F is output, the sub-scanning drive motor 3 is driven, and the line feed operation is performed. Return to step 106.

At step 106, the image data B of the next line is read. The number of print pixels K = 6 in step 107
To calculate. In step 108, the number of print pixels K =
Since 6 is the upper limit number of heating elements N = 7 or less, step 10
9, the heat generation data B1 ′ is created from the image data B, the process proceeds from step 111 to step 112, and the image described second from the left side in (g) of FIG. 7 is printed. Since all the heat generation data has been output, the process proceeds from step 113 to step 114. Since printing for one page has not been completed, the process proceeds from step 114 to step 115, the sub-scanning drive motor 3 is driven to perform a line feed operation, and the process returns to step 106.

At step 106, the image data C of the next line is read. The number of print pixels K = 1 in step 107
Calculate 2. In step 108, the number of print pixels K
= 12 is larger than the upper limit number of heating elements N = 7, the process proceeds to step 110. In step 110, the number of print pixels included in each heat generation data becomes equal to or less than the upper limit number N = 7 of heating elements,
In addition, since the heat generation data is created so that the number of print pixels included in each heat generation data is as equal as possible, from the image data C as shown in FIG.
Two pieces of heat generation data C1 ′ and C2 ′ are created as shown in FIG. After that, the heat generation data C1 'and the heat generation data C2' are sequentially printed, the rightmost image in FIG. 7G is printed, and the process proceeds to step 114. If the printing for one page is completed, the process proceeds to step 116. When printing the next page, the process proceeds to step 117, a page break is performed, and the process returns to step 106. When printing is completed on this page, the process proceeds from step 116 to end and the operation is completed.

As is clear from the above description, in the present embodiment, the upper limit number N of heating elements is determined based on the battery voltage, and the upper limit is the number K of printing pixels existing on one main scanning line of image data. When the number of heat generating elements is larger than N, the image data is divided into a plurality of heat generating data having the number of print pixels equal to or less than the upper limit number of heat generating elements, and the printing is sequentially performed. Therefore, the same image data may be printed. However, the battery voltage is low (5
When the battery voltage is higher (6 V) than in V), printing can be performed with a small number of heat generations, that is, a small number of printings, and an unnecessary increase in the number of heat generations can be prevented. Therefore, it is possible to perform printing in an appropriate printing time according to the voltage of the mounted battery.

By performing the above-described operation, when the voltage of the battery 30 is low, the number of times of printing is larger than when the voltage of the battery 30 is high, but the maximum value of the thermal head current is small. Therefore (see FIGS. 6 and 7 (h)), it is possible to reliably perform printing even when the battery usage time increases and the battery voltage becomes low, and a small battery is used. Therefore, printing can be performed for a long time.

In this embodiment, the voltage V of the mounted battery 30 is measured at the time of starting the apparatus and the upper limit number of heating elements is set according to this voltage V, but the present invention is not limited to this. Instead, for example, the voltage of the battery 30 may be measured at predetermined time intervals to newly set the upper limit number of heating elements, or the upper limit number of heating elements may be set for each page break or line feed. In such a case, it is possible to perform printing at an appropriate printing speed correspondingly to the voltage change of the battery 30 caused by the environmental temperature change or the temperature change of the apparatus itself. As the upper limit number of heating elements, 4 and 7 are 2
I set the number of types, but increased the number of types of upper limit heating elements,
The voltage V of the battery 30 may be made to correspond in detail, and the printing speed can be controlled more efficiently.

Next explained is a thermal printing apparatus which is a second embodiment to which the method and apparatus for controlling the heating element of the thermal head of the present invention is applied. The overall structure is shown in Fig. 1.
Since there are many common parts with the first embodiment shown in FIG. 3, only different component numbers are added in the figure. Descriptions of elements common to the first concrete embodiment will be omitted unless particularly necessary.

The control unit 40 of the thermal head of the thermal printing apparatus in this embodiment has the voltage V of the battery 30 detected by the battery voltage detection unit 31 at the time of starting the apparatus and the preset reference voltage value VS. If the voltage V is larger than the reference voltage value VS, one heat generation data is created from the input image data of one line and printing is performed. If the voltage V is less than the reference voltage value VS, The image data is divided into two pieces of heat generation data, and the two pieces of heat generation data are sequentially printed.

With this control operation, even when the same image data is printed, when the battery voltage is high, printing can be performed with a smaller number of heat generations than when the battery voltage is low. Therefore, it is possible to prevent an unnecessary increase in the number of heat generations. Therefore, it is possible to perform printing in an appropriate printing time according to the voltage of the mounted battery. Further, since printing can be performed even when the usage time of the battery is increased and the battery voltage is lowered, it is possible to perform printing for a long time using a small battery. Moreover, since these effects can be obtained with simple control software,
In particular, it is suitable for a device such as a bar code printing device in which the number of print pixels for each line is small.

In this embodiment, the voltage V of the mounted battery 30 is measured and the number of divisions of the image data is set when the apparatus is started, but the present invention is not limited to this. For example, the voltage of the battery 30 may be measured at predetermined time intervals and a new division number may be set, or a new division number may be set for each page break or line feed. In such a case, it is possible to perform printing at an appropriate printing speed correspondingly to the voltage change of the battery 30 caused by the environmental temperature change or the temperature change of the apparatus itself. Further, although two or two types of division numbers are set as the number of divisions, the number of division numbers may be increased and may correspond finely to the voltage V of the battery 30, and the printing speed can be controlled more efficiently. can do.

In each embodiment, the battery 30
When measuring the voltage V, the voltage is detected in the state where the sub-scanning drive motor 3 is connected to the battery 30 as a load, so the voltage close to the battery voltage during actual operation is measured. can do.

In each of the embodiments, the heating element control method and control device for a thermal head of the present invention is applied to a thermal printing apparatus, but the present invention is not limited to this and is also applicable to a thermal stencil plate making apparatus or the like. It can be applied, and similarly, plate making can be performed at an appropriate plate making time according to the battery voltage.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a thermal printing apparatus according to first and second embodiments of the present invention.

FIG. 2 is a sectional view of the thermal printing apparatus according to the first embodiment.

FIG. 3 is a block diagram of a control unit according to the first embodiment.

FIG. 4 is a flowchart illustrating an operation flow of a control unit according to the first embodiment.

FIG. 5 is an explanatory diagram of image data.

FIG. 6 is an explanatory diagram of each control signal and print image.

FIG. 7 is an explanatory diagram of each control signal and print image.

FIG. 8 is a diagram showing changes over time in battery voltage and voltage applied to a heating element.

[Explanation of symbols]

1 Thermal paper 2 Platen roller 3 Sub-scanning drive motor 4 Gear section 10 thermal head 11 heating element 12 Lead electrode 13 board 20,40 Control unit 30 batteries 31 Battery voltage detector 201 pixel number calculation unit 202 Current supply controller

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryoichi Imai             2-20-15 Shimbashi, Minato-ku, Tokyo Ideal science             Industry Co., Ltd. (72) Inventor Xue Hua             2-20-15 Shimbashi, Minato-ku, Tokyo Ideal science             Industry Co., Ltd. F term (reference) 2C066 AA01 AA03 AA08 AB02 AB05                       AB07 CB01 CB06 CB09 CF03                       CF07

Claims (5)

[Claims] 1. A method of controlling a heating operation of a heating element of a thermal head in which a plurality of heating elements are arranged in a row in a main scanning direction based on input image data, wherein the heating operation includes: It is carried out by supplying the current of the battery to the heating element, detecting the voltage of the battery, and based on the detected voltage, the upper limit heat generation, which is the number of the heating elements capable of simultaneously supplying the current. The number of heat generating pixels is determined, the number of heat generating pixels existing on one main scanning line in the image data is obtained, and when the number of heat generating pixels is larger than the upper limit number of heat generating bodies,
It is characterized in that the image data is divided into a plurality of blocks in which the number of heat-generating pixels is equal to or less than the upper limit number of heat-generating elements, and each block is controlled so that current is supplied to the heat-generating elements at different timings. Control method for heating element of thermal head. 2. A method for controlling a heating operation of a heating element of a thermal head in which a plurality of heating elements are arranged in a row in a main scanning direction based on input image data, wherein the heating operation includes: This is performed by supplying the current of the battery to the heating element. When the voltage of the battery is detected and the detected voltage is below a predetermined value, the image data is divided into a plurality of blocks. The heating element control method for a thermal head, characterized in that the heating element is controlled so that current is supplied to the heating element at different timings for each block. 3. A device for controlling a heating operation of a heating element of a thermal head in which a plurality of heating elements are arranged in a row in a main scanning direction based on input image data, wherein the heating operation includes: This is performed by supplying a current of a battery to the heating element, and a battery voltage detection unit that detects the voltage of the battery, and a heat generation that determines the number of heating pixels present on one main scanning line in the image data. Based on the pixel number calculation means and the voltage detected by the battery voltage detection means, an upper limit number of heating elements, which is the number of the heating elements capable of simultaneously supplying current, is determined, and the upper limit number of heating elements and the heating pixel If the number of heating pixels is larger than the upper limit number of heating elements, the image data is set so that the number of heating pixels included in one block is less than or equal to the upper limit number of heating elements.
A heating element control device for a thermal head, comprising: a plurality of blocks; and a current supply control means that controls each block so that a current is supplied to the heating element at different timings. 4. A device for controlling a heat generating operation of a heat generating element of a thermal head in which a plurality of heat generating elements are arranged in a row in a main scanning direction based on input image data. This is performed by supplying the current of the battery to the heating element, and a battery voltage detecting means for detecting the voltage of the battery, and if the detected voltage is below a predetermined value, the image data Is divided into a plurality of blocks, and a current supply control means for controlling the current to be supplied to the heating elements at different timings for each block, and a heating element control device for a thermal head. 5. The battery voltage detecting means detects the voltage of the battery in a state where a motor for moving a thermal paper is connected to the battery as a load. Alternatively, the heating element control device of the thermal head according to the item 4.