JPH0339265A - Applied pulse controller in thermal transfer printer - Google Patents

Abstract

PURPOSE:To set an appropriate pulse to be applied to perform a high-quality printing by providing an applied pulse setting means for setting an energy of a pulse to be applied to a thermal head from the temperature of a thermal head substrate and printing data of one line before. CONSTITUTION:Data per dot or block 28 for a line to be applied to a thermal head is temporarily held in a first memory device 16. Data per dot or block 28 for the same part one line previous to said data is temporarily held in a second memory device 18. The data held in the memory devices 16, 18 are added to each other by an adding means 21. Based on the temperature of a thermal head substrate measured by a measuring means 24 and the sum, an energy of a pulse to be applied to the thermal head is set by an applied pulse setting means 23. In this manner, when a halftone is reproduced by a dither method or the like, a high-printing quality can be realized.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control device for applying pulses applied to a line-type thermal head of a thermal transfer printer, and in particular to a device for correcting thermal energy using data printed in the past. The present invention relates to an application pulse control device.

[Conventional technology]

Thermal transfer printers are often used, for example, in small Japanese word processors, and have excellent features such as no noise and the ability to easily express halftones when using heat dye sublimation ink.

Since the temperature of the substrate of the thermal head used in such a printer is low when printing is performed first thing in the morning, it is necessary to provide sufficient thermal energy to each printed dot. On the other hand, when new printing is performed immediately after printing on a number of sheets, the temperature of the substrate has risen sufficiently. Therefore, unless a smaller amount of thermal energy is applied than described above, an excessive amount of thermal energy will be supplied, resulting in problems such as enlarged printed dots.

For this reason, in the past, a temperature detection element such as a thermistor was attached to the substrate of the thermal head, and an appropriate pulse could be applied to each dot or block of the thermal head according to the detected temperature. Ta.

[Problem to be solved by the invention]

In this way, with conventional line-type thermal heads, the temperature of the thermal head's substrate immediately before applying an applied pulse is measured, and only this temperature value is used to set the width or peak value of the applied pulse for the next line. . For this reason, if there is a discrepancy between the actual temperature of the heating resistor part of the thermal head and the substrate temperature, more or less thermal energy will be applied than is actually required, resulting in printing There was a problem that the quality may deteriorate.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an application pulse control device for a thermal transfer printer that is capable of determining applied energy taking into account not only the substrate temperature of a thermal head but also the state of heat storage in a heating resistor. be.

[Means to solve the problem]

In the present invention, the first storage means temporarily stores the data of the dots or blocks of the line to be applied to the (+) line type thermal head, and (11) the i-line of the above line of the line type thermal head. (iii) an addition means for adding the data held in the first and second storage means;
) a substrate temperature measuring means such as a thermistor for measuring the temperature of the substrate of the line type thermal head; and (v) an electric current applied to the line type thermal head based on the measurement result of the substrate temperature measuring means and the addition result of the adding means. The application pulse control device of the thermal transfer printer is provided with an application pulse setting means for setting the energy of the pulse.

That is, in the present invention, the substrate temperature measurement means not only measures the substrate temperature of the thermal head, but also measures the data of the dot or print block to be printed now and the data of a similar dot or print block one line before. The addition means adds the values, thereby making it possible to control the applied pulses taking -Cm heat into consideration.

"Example〕 Hereinafter, the present invention will be described in detail with reference to Examples.

FIG. 1 shows the main parts of a thermal transfer printer using an application pulse control device according to an embodiment of the present invention.

A print data signal 12 consisting of a data string to be printed every second and a storage device switching signal 13 are alternately input to a data transfer switching device 11 of a thermal transfer printer. The data transfer switching device 11 is equipped with two systems of output terminals and terminals.
The print data signal 14 output from the output terminal is input to a first storage device 16 within the thermal control device 15.

Further, the print data signal 17 output from the second output terminal of the data transfer switching device 11 is input to a second storage device 18 in the thermal control device 15. The data transfer switching device 11 switches the terminal to which the print data signal 12 is output every time the storage device switching signal 13 is input, so that one of the first and second storage devices i6.18 is currently being printed. The print data of the line is stored, and the print data of the line used for previous printing remains in the other.

These two types of print data signals at the same main scanning position are supplied to an adder 21 and added as signals for each corresponding dot. At this time, the weights in the addition need not be equal; for example, it is effective to add the print data of the line to be printed currently with a larger weight than the print data of the line printed last time.

The print data 22 of each dot added by the adder 21 is supplied to the determiner 23. The determiner 23 is also supplied with temperature data 25 from a thermistor 24 attached to a substrate (not shown) of the line type thermal head.

The determiner 23 sets the width of the applied pulse when printing this time based on two types of data: the substrate temperature and the print data 22. Then, this applied pulse width information 26 is supplied together with the current print data 27 to the corresponding dot or block 28 of the thermal head. Here, the determiner 23 sets the width of the applied pulse to be longer when the substrate temperature is low. Also,
The larger the value of the print data after addition, the greater the influence of heat storage and current thermal energy, so the applied pulse is set short. These correlations may be determined through experiments and stored as a table in a ROM table within the determiner 23, for example. Of course, it is also possible to define an arithmetic expression and calculate the applied pulse according to each individual situation.

When the thermal head finishes printing the corresponding dot or block 28, the next print data signal 12 is processed in the same way, and when the dot or block processing is completed a predetermined number of times in this way, 1947 minutes of printing is completed. The work will be completed. The number of blocks is not necessarily constant depending on the bottom of the tank of the thermal head, but is, for example, about 8 blocks or 4 blocks.

In the embodiment described above, both the applied pulse width information 26 and the current print data 27 are outputted from the determiner 23, but only the applied pulse width information 26 is outputted, and print data is separately supplied to the thermal head. You can do it like this. Further, in the embodiment, the applied energy is adjusted by controlling the width of the applied pulse, but it is also possible to set the applied energy to a desired value by adjusting the peak value of the applied pulse.

〔Effect of the invention〕

As described above, according to the present invention, the pulses applied to the thermal head in a thermal transfer printer using a thermal head are adjusted not only by the substrate temperature of the thermal head but also by using the printing data of the previous line, so that the pulse applied to the thermal head can be adjusted appropriately. This makes it possible to set appropriate applied pulses, making it possible to achieve high quality printing, especially when reproducing halftones using a dither method or the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an application pulse control device and its surroundings for a thermal transfer printer according to an embodiment of the present invention. 11... Data transfer switching device, 12...
・Print data signal, 16...first storage device (first or second storage means), 18...second storage device (first or second storage means) , 21...adder, 23...determiner, 2
4... Thermistor, 28... Dot or block (of the thermal head).

Claims (1)

[Scope of Claims] A first storage means for temporarily holding data of dots or blocks of a line to be applied to a line-type thermal head; a second storage means for temporarily holding dot or block data; an addition means for adding the data held in the first and second storage means; and measuring the temperature of the substrate of the line type thermal head. and an application pulse setting means for setting the energy of the application pulse to be applied to the line type thermal head based on the measurement result of the substrate temperature measurement means and the addition result of the addition means. Features: Application pulse control device for thermal transfer printers.