JP2001232843A - Thermal printer and method of recording therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer and a method of recording therefor capable of improving a battery life and increasing a number of sheets to be printed by one battery by a method wherein a maximum usage current to be used in simultaneous energization of heating elements is suppressed. SOLUTION: This thermal printer includes a setting section 6 for setting a value of the use maximum current to be used in the simultaneous energization of the heating elements 2 corresponding to a performance of the battery 5. The printer further includes a control section 7 for controlling in such a manner that when the total value of the energizing currents of the heating elements 2 to be used in the simultaneous energization exceeds the value of the use maximum current, the number of heating elements 2 to be used in the simultaneous energization is limited so that the total value is not greater than at least the use maximum current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer and a recording method therefor, and more particularly to a battery as a drive source for selectively energizing a plurality of heating elements formed on a thermal head by the battery. Accordingly, the present invention relates to a thermal printer for performing desired recording by causing each heating element to generate heat and a recording method thereof.

[0002]

2. Description of the Related Art Conventionally, a thermal head in which a plurality of heating elements are arranged and arranged is mounted, and by selectively controlling the energization of each heating element of the thermal head, each heating element is caused to generate heat to a desired value. Thermal printers for performing recording have been frequently used for reasons such as high print quality.

Further, the thermal printer has a simple mechanism in addition to high print quality and is suitable for compactness. Therefore, the thermal printer is often used as an output device of a so-called portable electronic device.

A thermal printer used in such a portable electronic device cannot use a commercial power supply unlike a so-called stationary thermal printer, and therefore a battery such as an alkaline battery is used as a power supply.

In such a thermal printer using a battery as a power source, a current supplied from the battery is selectively supplied to a heating element formed in a thermal head under the control of a control circuit. In addition, desired recording is performed on recording paper by causing each heating element to generate heat.

[0006]

However, in such a thermal printer using a battery as a power source, a large amount of current is required to generate heat in each heating element of the thermal head.

In general, the life of a battery is long for use with low power consumption, but tends to be sharply shortened when high power consumption is continued. Since the heating elements were energized at the same time, the power consumption was considerably high.

For this reason, there has been a problem that the life of the battery cannot be maintained long, and the number of printable sheets per battery cannot be improved.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the battery life is improved by suppressing the maximum use current used for the simultaneous energization of the heating elements, so that the number of printable sheets per battery can be reduced. It is an object of the present invention to provide a printer and a recording method thereof that can be improved.

[0010]

In order to achieve the above object, a thermal printer according to the present invention is characterized in that a maximum use current value used for simultaneously energizing the heating elements is set to a value corresponding to the performance of a battery. The setting unit is provided, and when the total value of the energizing current to each heating element that performs simultaneous energization exceeds the maximum use current value, the total value of the energizing current is reduced by limiting the number of heating elements that perform simultaneous energization. The present invention is characterized in that a control unit for controlling so as to be at least equal to or less than the maximum use current value is provided.

[0011] By adopting such a configuration, the maximum current value used for simultaneous energization of the heating elements can be controlled according to the performance of the battery.
The battery life can be improved, and the possible number of prints per battery can be improved.

The recording method of the thermal printer according to the present invention is characterized in that a maximum use current value used for simultaneous energization of the heating elements is set at a value corresponding to the performance of the battery, and that the simultaneous energization is performed. When the total value of the energizing currents to the heating elements exceeds the maximum use current value, the total value of the energization currents is at least equal to or less than the maximum use current value by limiting the number of heating elements that are simultaneously energized. The point is to control.

[0013] By adopting such a method, the maximum current used for simultaneous energization to each heating element can be controlled in accordance with the performance of the battery, so that the battery life can be improved. At the same time, the number of prints that can be performed per battery can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a thermal printer according to the present invention will be described below with reference to FIG.

As shown in FIG. 1, a thermal printer 1 according to the present embodiment has a thermal head 3 in which a plurality of heating elements 2 are formed in parallel with each other.

Each of the heating elements 2 is connected to a drive circuit 4 for driving the heating elements 2. The drive circuit 4 drives each heating element 2 by turning on / off a switch such as a switching transistor. The drive circuit 4 is connected to a battery 5 as a power supply.

The thermal printer 1 has a setting unit 6 for setting a maximum value of a current used for simultaneous energization of the heating elements 2 (hereinafter, referred to as a maximum use current value).
The setting unit 6 is configured to set a maximum use current value according to the performance of the battery 5 such as a power characteristic with respect to a load current. The setting unit 6 includes, for example, AA batteries,
It may be a memory for storing data of the maximum use current value according to the type of the battery 5 used in the thermal printer 1 such as a AAA battery. Further, the setting of the maximum use current value in the setting section 6 may be performed at the time of assembling the thermal printer 1. Note that the performance and the maximum current value of the battery 5 may be determined based on the results of various characteristic tests performed on the battery 5 in advance.

The thermal printer 1 has a control unit 7 for performing various controls such as driving control of the heating element 2 based on print data input from a host device.

The control unit 7 controls the heating element 2 to perform simultaneous energization based on the maximum current value set in the setting unit 6.
The number is controlled. That is, when the total value of the current supplied to each of the heat-generating elements 2 that conducts the current simultaneously exceeds the above-mentioned maximum current value, the control unit 7 restricts the number of the heat-generating elements 2 that simultaneously conducts the current. Is controlled so as not to exceed at least the use maximum current value.

For example, in a state where the internal resistance of the battery 5 is neglected, the maximum current value used is I, the electromotive force of the battery 5 is V, the resistance of each heating element 2 is r, and the number of heating elements 2 that are energized simultaneously. Is assumed to be X. In this case, the combined resistance R of the heating elements 2 that are energized at the same time is represented by R = r / X from the general formula of the combined resistance in parallel. The electromotive force V is converted to the combined resistance R
Is the current flowing through the entire circuit, that is, the total value VX / r of the currents flowing to the respective heating elements 2 that are simultaneously energized.
Becomes When the value of the total value VX / r exceeds the maximum use current value I, that is, VX / r> I
In such a case, the control is performed such that the total value VX / r does not exceed at least the maximum use current value I by reducing the number X of the heating elements 2.

Next, an embodiment of a recording method for a thermal printer according to the present invention to which the thermal printer 1 is applied will be described. In the present embodiment, the battery 5
Of the battery 5 is 5 V, the resistance of each heating element 2 is 200 Ω, and the maximum current value used is 1 A.

First, the control section 7 receives print data from a host device, and determines the heating elements 2 to be energized simultaneously based on the print data.

At this time, the control unit 7 controls the setting unit 6
The data of the maximum use current value is read from the CPU, and it is determined whether or not the total value of the current supplied to the heating elements 2 that are energized simultaneously based on the print data exceeds the maximum use current value. That is, assuming that the number of the heating elements 2 that perform simultaneous energization is X, the combined resistance R of the heating elements 2 that perform simultaneous energization is R = 200 / X from the general formula of the parallel combined resistance. Since the electromotive force is 5 V, the total value of the current supplied to the heating elements 2 that are simultaneously energized is 5X / 200A. The number of heating elements X so that the total value does not exceed the maximum use current value 1A
Is 40. Therefore, when the number of the heating elements 2 that perform simultaneous energization is 41 dots or more, the control unit 7 determines that the total value of the conduction currents to the heating elements 2 that perform simultaneous energization exceeds the maximum use current value. .

If the control unit 7 determines that the total value of the current supplied to the heating elements 2 that are energized simultaneously does not exceed the maximum current value for use, the control unit 7 does not control the number of heating elements 2. Then, a drive command for each heating element 2 is output to the drive circuit 4 as it is, and simultaneous energization is performed.

On the other hand, if the control unit 7 determines that the total value of the currents flowing through the heating elements 2 that are energized simultaneously exceeds the maximum current value used, the control unit 7 determines the number of the heating elements 2 that are energized simultaneously. Limit the value to at least the upper limit. Then, a command is issued to the drive circuit 4 for the limited number of simultaneous energizations. Note that limiting the number of heating elements 2 that perform simultaneous energization means that simultaneous energization to the heating elements 2 is performed in at least two stages. The heating elements may be divided into two groups and two even-numbered heating elements.

As a result, it is possible to suppress the total value of the currents flowing to the heating elements 2 that are energized at the same time to be equal to or less than the maximum use current value.

Next, an evaluation test performed on the battery 5 will be described as an example of a means for determining the performance of the battery 5 and the maximum current value to be used based on the performance of the battery 5.

The evaluation of the battery 5 in this test takes into account the target printing time of the thermal printer 1 that performs printing using the battery 5. That is, the thermal printer 1 uses a built-in roll paper as a recording paper, and the roll paper has a maximum length of 2 m. The printing speed is 1 IPS, and printing of two or more turns is performed. In this case, a printing time of 4000 mm / 25.4 mm = 157 seconds or more is required. If the printing time longer than the above-mentioned time can be secured in solid black printing, the printing time can be secured twice or more in the case of normal characters. For this reason, if the printing is performed with a duty ratio of 20% or less for a character or the like, it is possible to print 10 turns, which is five times the black solid. Therefore, the target printing time of the thermal printer 1 is set to 150 seconds or more, and the battery 5 is evaluated.

In this test, the load current of each battery 5 and the characteristics of the printing time of the thermal printer 1 with respect to this load current were examined for AA batteries and AAA batteries. In this test, the voltage of the battery 5 was set to 1 V at the end. The results are shown in the table below.

[0030]

[Table 1]

As shown in Table 1, when the load current is increased in each battery, the printing time and the power which is the product of the printing time and the load current are extremely reduced.

For example, when the load current is increased from 1.5 A to 3 A with AA batteries, or when the load current is 1 A with AAA batteries.
When the print time is increased from 1 to 2 A, the print time is not simply reduced by half, but is reduced by about 1/10. This extremely low current range is caused by the battery reaction capacity and the internal impedance of the battery, and it is necessary to use the battery in the current range or less from the viewpoint of improving the life of the battery and the possible number of prints. .

Therefore, AA batteries have a maximum current value of 1.
A value within 5A is appropriate, and at worst, a value within 2A is desirable. It is appropriate for the AAA battery to have a maximum use current value of 1 A or less, and it is desirable that the maximum current value be 1.5 A or less at worst.

Therefore, according to the present embodiment, the battery 5
Since the maximum current used for the simultaneous energization of the heating elements 2 can be controlled in accordance with the performance of the battery, the battery life can be improved, and the possible number of prints per battery 5 can be improved.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified as needed.

[0036]

As described above, according to the thermal printer and the recording method thereof according to the present invention, the life of the battery can be improved, and the possible number of prints per battery can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a thermal printer according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal printer 2 Heating element 3 Thermal head 4 Drive circuit 5 Battery 6 Setting part 7 Control part

Claims (2)

[Claims] 1. A thermal printer that uses a battery as a power source and selectively energizes a plurality of heating elements formed on a thermal head by the battery, thereby causing each heating element to generate heat and performing desired thermal transfer recording. A setting unit for setting a maximum current value used for simultaneous energization to the heating elements with a value according to the performance of the battery is provided. When the current value exceeds the maximum current value, a control unit is provided that controls the total value of the currents to be at least equal to or less than the maximum current value by limiting the number of heating elements that are simultaneously energized. And a thermal printer. 2. A recording method for a thermal printer, wherein a plurality of heating elements formed on a thermal head by a battery are selectively energized to cause each heating element to generate heat and perform desired thermal transfer recording. When the maximum current value used for simultaneous energization to the heating elements is set at a value according to the performance of the battery, and the total value of the currents applied to the heating elements performing simultaneous energization exceeds the maximum usage current value The present invention relates to a recording method for a thermal printer, wherein the number of heat-generating elements that are simultaneously energized is controlled so that the total value of the energizing current is at least equal to or less than the maximum use current.