JPH07314760A - Thermal printing device - Google Patents

Abstract

PURPOSE:To prevent the rapid fall of voltage from developing and prolong the life span of cells by a method wherein the maximum number of simultaneously printable black dots is changed in proportion to the change of the voltage of the cells in a cell-driving type thermal printing device. CONSTITUTION:This thermal printing device is equipped with a black dot counter 4, which measures the number of black dot data in printing data, and a dividing means (or a data transferring means 3) for dividing the printing data into dividends, each of which contains (n) black dot data (in which (n) is the maximum number of simultaneously printable black dots). On the basis of the voltage detected with a voltage detecting means 5, the value (n) in the dividing means is changed. Accordingly, in a cell-driving type thermal printing device, the maximum number of simultaneously printable black dots can be decided in proportion to a voltage of cells, resulting in preventing the rapid fall of voltage from developing and allowing to prolong the life span of the cells.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printing apparatus which uses a battery as a power source.

[0002]

2. Description of the Related Art The operation of a conventional thermal printer is shown in FIG.
Will be explained.

In FIG. 3, reference numeral 1 denotes a thermal print head for printing on a thermal paper, and a heating element among a plurality of heating elements to which an electric current is applied generates heat. The thermal print head 1 prints a black dot on a portion of the thermal paper heated by the heating element. Reference numeral 2 is a memory for holding data to be printed, and 3 is a data transfer means for transferring print data from the memory 2 to the thermal print head 1.
Reference numeral 5 is a voltage detecting means for detecting the voltage of the battery 6, which is a power source.

The operation of the conventional thermal printer shown in FIG. 3 will be described below. If the battery voltage is equal to or higher than the specified voltage by the voltage detection means 5, the print data of one line stored in the memory 2 is extracted by the data transfer means 3 in equal divisions, and the other part is filled with white data to form one line. Data is transferred to the thermal print head 1 and printing is executed.

If the battery voltage is lower than the specified voltage by the voltage detecting means 5, it is judged that printing is impossible and the printing is interrupted.

[0006]

However, in the conventional thermal printing apparatus, the amount of print data (division width) transferred to the thermal print head at one time is fixed.
A current is generated according to the number of black dot data in the print data, and the print density may be lowered or malfunction due to a voltage drop due to the internal resistance of the battery. In order to prevent this, it is necessary to set the print stop voltage to a high value, the battery capacity cannot be used up, and the battery life is shortened equivalently.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a thermal printing apparatus capable of setting a print stop voltage lower than in the past and extending battery life. .

[0008]

In order to solve the above problems, the present invention provides a voltage detection unit for detecting a power supply voltage,
A counter that counts the number of black dot data in the print data,
A dividing unit that divides the print data so as to include a maximum of n black dot data, and the value of n (the maximum number of black dots that can be printed simultaneously) in the dividing unit is changed based on the voltage detected by the voltage detection unit. A means for controlling to do so is provided.

[0009]

According to the present invention, the number of black dot data that can be printed at one time can be changed by the voltage of the battery driving the thermal print head to control the voltage drop due to the internal resistance of the battery. It will be possible.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
Will be described with reference to.

FIG. 1 is a block diagram of a thermal printer according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a thermal print head for printing on thermal paper, and among the plurality of heating elements of the thermal print head 1, the heating elements to which electric current is applied generate heat and transfer this heat to the thermal paper. Therefore, a black dot is printed on a portion of the thermal paper heated by the heating element.

Reference numeral 2 is a memory for holding data to be printed, and reference numeral 3 is a data transfer means for transferring print data from the memory 2 to the thermal print head 1.

Reference numeral 4 is a black dot counter for counting the number of black dot data in the print data, and reference numeral 5 is a voltage detecting means for detecting the voltage of the battery as a power source.

The operation of the thermal printing apparatus according to the embodiment of the present invention shown in FIG. 1 will be described below. FIG. 2A shows an example of print data stored in the memory 2. Figure 2
2B shows print data division points when the battery voltage is equal to or higher than the specified voltage, and FIG. 2C shows print data division points when the battery voltage is equal to or lower than the specified voltage.

The 1-line print data stored in the memory 2 is counted by the black dot counter 4 when being read from the memory 2. Based on the count value of the black dot counter 4, the data transfer means 3 divides the print data of one line so as to include at most n black data.

For example, when the battery voltage is equal to or higher than the specified voltage V1 by the voltage detecting means 5, the value of n is set to 16, and the data transferring means 3 sets a maximum of 16 black data as shown in FIG. 2 (b). Split to include. That is, FIG. 2 (b)
In the above example, the black dot counter 4 counts the number of black dot data from the left end of the drawing, and the value of the black dot counter 4 is 1
The print data is divided at the position t1 when the value becomes 6. At this time, the black dot counter 4 is reset.

Next, the data transfer means 3 extracts only the data of one divided group (print data up to the position t1), and the other part is filled with white dot data and transferred to the thermal print head 1 as one line data. Then, the thermal print head 1 executes printing. That is,
Only one of the plurality of heating elements of the thermal print head 1 to which the data of one divided group is sent executes printing.

When the printing of the data of one group is completed, the position t at which the value of the black dot counter 4 becomes 16 again
The print data is divided at 2, and the black dot counter 4 is reset as before.

Then, the data of this group is extracted,
Similarly to the previous time, the data is transferred to the thermal print head 1, and the thermal print head 1 prints the data of the divided group. By repeating this for all the print data for one line on the memory 2, the print data for one line is printed.

As described above, when the battery voltage is equal to or higher than the specified voltage V1, the value of n is set to 16, and the data transfer means 3 divides it so as to include a maximum of 16 pieces of black data, but it takes a long time. When the battery voltage drops due to use, the value of n is changed to a smaller value. For example, when the battery voltage is equal to or lower than the specified voltage V1 and equal to or higher than V2 (<V1), the value of n is set to 8. That is, the detection output of the voltage detection means 5 is V2 (<V when the battery voltage is the specified voltage V1 or less).
1) When the above is indicated, the data transfer means 3 divides so as to include a maximum of eight black dot data as shown in FIG.

In the example of FIG. 2 (c), the black dot counter 4 counts the number of black dot data from the left end of the drawing, and the print data is divided at the position t3 when the value of the black dot counter 4 becomes 8, The black dot counter 4 is reset.
Similarly to the previous time, the data transfer means 3 extracts only the data of one division group (print data up to the position t3), the other part is filled with white dot data and transferred to the thermal print head 1 as one line data, The thermal print head 1 executes printing.

When the printing of the data of one group is completed, the position t4 at which the value of the black dot counter 4 reaches 8 again
The print data is divided at, and the black dot counter 4 is reset as in the previous time.

Then, the data of this group is extracted,
Similarly to the previous time, the data is transferred to the thermal print head 1, and the thermal print head 1 prints the data of the divided group. By repeating this for all the print data for one line on the memory 2, the print data for one line is printed after the division at the positions t5 and t6.

If the battery voltage is equal to or lower than the specified voltage (V2) by the voltage detecting means 5, it is judged that printing is impossible and the printing is interrupted.

As described above, the battery voltage is the specified voltage V1.
If it is above, printing is possible even if the value of n is increased,
Even if the battery voltage drops due to long-term use, the value of n is changed to a small value, so that the power taken out from the battery can be reduced and printing can be continued as long as possible. Although the black dot data is limited to two levels in this embodiment, the value of n may be finely changed as the battery voltage decreases.

[0026]

As described above, the present invention detects the voltage value of a battery in a battery-operated thermal printer and controls the maximum number of black dot data that can be simultaneously printed according to the detection result. With this configuration, it is possible to set the print stop voltage lower than before, prevent a sudden voltage drop, and extend the battery life.

[Brief description of drawings]

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

FIG. 2A is an explanatory diagram showing an example of print data of the thermal printer according to the present invention, and FIG. 2B is an explanatory diagram showing division points of the print data when the battery voltage is equal to or higher than a specified voltage. Explanatory drawing showing division points of print data when battery voltage is below specified voltage

FIG. 3 is a block diagram showing an example of a conventional thermal printer.

[Explanation of symbols]

 1 thermal print head 2 memory 3 data transfer means 4 black dot counter 5 voltage detection means

Claims (3)

[Claims] 1. A thermal print head for printing on thermal paper, voltage detection means for detecting a power supply voltage, a memory for holding print data, and the number of black dot data in the print data stored in the memory. A counter that counts the number of black dot data to be printed at one time according to the power supply voltage detected by the voltage detection means, from the count value of the counter, and print data from the memory a plurality of times. A thermal printing device characterized in that it is divided into read pieces and sent to the thermal print head for printing. 2. A thermal printer according to claim 1, wherein the voltage detecting means detects the voltage applied to the thermal print head. 3. A thermal print head for printing on thermal paper, a voltage detector for detecting a voltage applied to the thermal print head, a memory for holding print data, and a memory for storing the print data. A counter that counts the number of black dot data in the print data and print data that includes a maximum of n (n: the maximum number of black dots that can be printed simultaneously) black dot data based on the count value of the counter. A dividing means for dividing and a print controlling means for dividing the reading into a plurality of times by the dividing means, reading out, sending to the thermal print head and printing, and the dividing based on the voltage detected by the voltage detecting section. A thermal printing apparatus comprising means for controlling so as to change the value of n in the means.