JPS60240271A - Heat sensing printer - Google Patents

Abstract

PURPOSE:To apply heat dissipation temperature control of a thermal head with simple circuit constitution by changing the pulse width applied to the thermal head. CONSTITUTION:The temperature of the thermal head 1 is detected by a head temperature detection sensor 6 and an output (i) in response to the temperature is obtained. The output (i) is subject to digital conversion by an A/D converter 8, inputted to an adder/subtractor 9 so as to control the pulse width of a print signal (g). Thus, as the temperature of the thermal head 1 increases, the output (g) of a print signal generating section 3 is a pulse width shorter than the pulse width corresponding to the gradation print data stored in a memory 4, the voltage applied time to the heating element of the thermal head 1 as a whole is short, resulting that the heat element of the thermal head 1 is brought into the heat dissipating temperature required for a prescribed gradation print without being affected with the entire temperature of the thermal head 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal printer that has a thermal head and a temperature detection sensor for the thermal head, and that compensates for the temperature of the thermal head.

Structure of the conventional example and its problems FIG. 1 shows the structure of the conventional example. 1 is the thermal head, 2
3 is a driver section that drives the thermal head; 3 is a print signal generation section; 4 is a memory that stores gradation print data; 5 is a clock generation section having a cycle corresponding to the minimum resolution; 6
Reference numeral 7 indicates a head temperature detection sensor that detects the temperature of the thermal head 1, and 7 indicates a drive voltage control unit that controls the drive voltage of the thermal head based on the output of the head temperature detection sensor 6.

Regarding the thermal printer configured as above, the following is as follows.
The operation will be explained assuming that gradation print data is stored in the memory in advance. - For example, when printing 16 gradations, the output & of memory 4 that stores gradation printing data is 4
If T is the period of the output C of the clock generator 5 which determines the time unit of the minimum resolution of the gradation printing reservoir, the print signal generator 3 synchronizes with the output C of the clock generator 5 and outputs the memory 4. The gradation print data a output from the clock generator 5 is input, and the pulse width is controlled so that the period T of the output C of the clock generator 5 is the time unit of the minimum resolution, and a print signal corresponding to the gradation print data is generated. output. Since the gradation print data is a 4-bit digital signal, the print signals are O, T, and 2T.

The pulse signal has a width of 3T, . . . , 15T.

The print signal is input to a driver section 2 that drives the thermal head 1, is amplified there, and applies a voltage to the heating element of the thermal head 1.

The temperature of the thermal head 1 is detected by a head temperature detection sensor 6, and an output d corresponding to the detected temperature is obtained. This output d is input to the drive voltage control section 7 and controls the voltage applied to the thermal head 1 by changing the drive voltage e applied to the driver section 2. As a result, when the temperature of the thermal head 1 increases, the driving voltage of the thermal head 1 decreases, and conversely, when the temperature decreases, the driving voltage of the thermal head 1 decreases.
The driving voltage becomes higher. Therefore, even if the temperature of the thermal head 1 changes, the temperature is compensated by changing the voltage applied to the head, and a heat generation temperature corresponding to a predetermined gradation can be obtained.

However, in the above configuration, the drive voltage control section 7 must directly control the voltage applied to the thermal head element, which not only requires a large capacity control element but also causes power loss in the control element. It had the problem of becoming larger.

Purpose of the Invention The purpose of the present invention is to solve the above-mentioned problems, and by changing the pulse width applied to the thermal head, it is possible to adjust the heating element of the thermal head to a predetermined gradation without being affected by temperature changes of the entire thermal head. An object of the present invention is to provide a thermal printer that generates heat at a temperature that suits the user's needs.

Structure of the Invention The present invention comprises a thermal head, a driver that drives the thermal head, a sensor that detects the temperature of the thermal head, a memory that stores gradation print data, and an A/D converter that converts the sensor output from an analog signal to a digital signal. an adder/subtractor that inputs the memory output and the A/D converter output, performs addition and subtraction, and outputs new gradation print data; and a print signal generator that inputs the gradation print data and obtains a pulse width corresponding to the gradation. This is a drive device for a thermal printer equipped with a thermal printer.By changing the pulse width applied to the thermal head in response to the temperature detection sensor output of the thermal head, the thermal head can be operated without being affected by the overall temperature of the thermal head. The heating element can be set to a heating temperature corresponding to a predetermined gradation.

Description of examples FIG. 2 shows an embodiment of the present invention.

Components 1 to 6 in the figure are the same as the components of the conventional example shown in FIG. 8 is an A/D converter that inputs the output of the head temperature detection sensor 6 and converts it from an analog signal to a digital signal;
Reference numeral 9 denotes an adder/subtractor which inputs the output of the A/D converter 8 and the output of the memory 4 storing gradation print data, performs addition or subtraction, and outputs new gradation print data.

The operation of the thermal printer configured as described above will be described below assuming that gradation print data is stored in the memory in advance.

As an example, when printing in 16 gradations, the output f of the memory 4 that stores gradation printing data is 4 bits.

The output 1 of the head temperature detection sensor 6 is set so that when the temperature of the thermal head 1 increases, the voltage increases and when the temperature decreases, the voltage decreases. The A/D converter 8 inputs the output i of the head temperature detection sensor and converts it into digital data. When the voltage of the sensor output 1 increases, the value of the A/D converter output cuff increases, and when the sensor output l voltage decreases, the A/D converter 8 inputs the output i of the head temperature detection sensor and converts it into a digital value. The D converter output output value becomes smaller.

As the temperature of the thermal head 1 rises, the value of the output from the A/D converter increases, and as the temperature decreases, the value decreases. Further, the adder/subtracter 9 outputs A/
Outputs a value within the D converter output output range. The gradation print data f outputted from the memory 4 in synchronization with the output of the clock generator 5 which determines the minimum resolution time unit for gradation printing is subtracted by the A/D converter output value in the adder/subtractor 9. and output as new gradation print data.

The print signal generator 3 inputs the addition/subtraction output k, controls the pulse width so that the period of the output of the clock generator 5 is the time unit of the minimum resolution, and generates a print signal according to the gradation print data. Output. If the output cycle of the clock generator 5 is T1 and the gradation print data is a 4-bit digital signal, the print signal g is O, T, 2T, 3T, . . .
..., a pulse signal with a width of 16T.

The print signal output g is input to the driver section 2, where it is amplified and applies a voltage to the heating element of the thermal head 10.

The temperature of the thermal head 1 is detected by a head temperature detection sensor 6, and an output 1 corresponding to the detected temperature is obtained. This output i is digitally converted by an A/D converter 8 and input to an adder/subtractor 9, thereby controlling the pulse width of the print signal g.

As the temperature of the thermal head 1 increases,
The output g of the print signal generator 3 has a pulse width shorter than the pulse width corresponding to the gradation print data stored in the memory 4, and the overall signal (voltage application time to the heating element of the head 1 is short, 1v1) As a result, thermal head 1
Thermal head 1 is not affected by the overall temperature.
The zero heating element can be brought to the heating temperature required for predetermined gradation printing.

In this embodiment, the heating element of the thermal head 1 is one example, but the thermal head 1 may be a line head having a plurality of heating elements. Further, although the number of bits of the memory 4 is assumed to be 4, it goes without saying that any number of bits may be used. In addition, in this embodiment, the output 1 from the A/D converter increases as the temperature of the thermal head increases, so the adder/subtractor performs subtraction. It goes without saying that if the adder/subtractor is configured so that the value of the output i becomes smaller as the value increases, the adder/subtractor only needs to perform addition.

Effects of the Invention In the present invention, when temperature-compensating the thermal head, the drive voltage of the thermal head is not directly controlled, so a large-capacity control element is not required, and power loss in the control element is also reduced. , the heat generation temperature of the thermal head can be controlled with a simple circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional example, and FIG. 2 is a block diagram showing a thermal printer according to an embodiment of the present invention. 1...Thermal head, 2...Head driver section, 3...Print signal generation section, 4...
...Memory, 5...Clock generator, 6...
. . . Head temperature detection section, Y . . . Head drive voltage control section, 8 . . . Human/D converter, 9 . . . Adder/subtractor. Name of agent: Masu Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] A thermal head, a driver that drives a heating element of the thermal head, a head temperature detection sensor that detects the temperature of the thermal head, a memory that stores gradation print data, and converts the output of the sensor from an analog signal to a digital signal. an A/D converter that adds or subtracts the gradation print data output from the memory and the output of the A/D converter to output new gradation print data; A thermal printer characterized in that it is equipped with a print signal generation section that receives outputted gradation print data as an input signal and generates a pulse width corresponding to the gradation.