JPH02281970A - Electric conduction control method in thermal head - Google Patents

Abstract

PURPOSE:To keep a peak temperature of each heating element constant to perform an electric conduction to each heating element with a proper conduction energy by a method wherein heating elements are divided into blocks, the total number of conduction dots is counted per block, and in accordance with the total number of conduction dots an electric conduction energy is incrementally/ decrementally corrected. CONSTITUTION:Heating elements 6 and conduction time controllers 9 are divided into blocks 10. A dot counter 11 for counting the number of conduction dots of each heating element 6 in each block 10 based on ON/OFF conduction data transmitted from an MPU 8 is connected between each conduction time controller 9 per block and the MPU 8. A correction arithmetic device 12 is also connected to the dot counter 11; the correction arithmetic device 12 inputs the number of counted dots from the dot counter 11, operates the total number of conduction dots, on the basis of the result operates incremental/decremental correction data for a conduction time of a drive voltage to each heating element 6, and outputs the result to each conduction time controller 9 in the same block 10. In this manner, an electric conduction to each heating element can be accurately controlled in accordance with the conduction state of the heating element.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for controlling energization of a thermal head, and in particular,
The present invention relates to a till 7J method for controlling energization of a thermal head, which makes it possible to perform proper printing by correcting the energization energy applied to a plurality of heating cords provided on the thermal head.

[Conventional technology]

In general, a thermal printer is equipped with a thermal head in which a plurality of heat generating elements are arranged in a straight line, and the thermal transfer medium such as an ink ribbon or thermal recording paper is placed relative to the thermal head in a direction perpendicular to the alignment direction of the heat generating elements. While moving, printing is performed while controlling the energization energy of each heating element.

Then, the present inventors counted the number of energized dots among the heating threads in one row, and updated the total energized area of each heating element every energization period of the heating element based on the number of dots. At the same time, an energization control method has already been proposed in which the magnitude of energization energy in the next energization cycle is adjusted based on this energization area so that the peak temperature of each heating element is kept constant.

FIG. 2 schematically shows an energization control device that implements the energization control method, and this energization control device calculates the total number of energized dots for one row of each heating element (not shown) of one normal head. an area correction calculator that calculates the OFF time of the driving voltage pulse of each heating element when the current-carrying area exceeds a set value by counting the number of energized dots and determining the total energized area of each heating element; 1. The area correction calculator 1 is inputted with the standard minimum OFF time for turning off the electricity to each heating element, and
Area-corrected OFF time and Moeki minimum O from device 1
Calculator 2 that calculates the FF time and outputs it as correction data
is connected. Further, an OFF time register 3 is connected to the adder 2, and the OFF time register 3 temporarily holds and outputs the correction data from the adder 2. A drive pulse shaper 4 is connected which shapes a drive voltage pulse whose pulse width is the value obtained by subtracting .

In the energization control method using such an energization control device, first, the area correction calculator 1 calculates a predetermined area correction value by calculating the total number of energized dots of each heating element by it vl, L/, and sends it to the adder 2. The adder 2 adds the area correction value and the minimum OFF time, and outputs the result to the 0FFn interval register 3 as correction data. This OF
The correction data once held in the F time register 3 is output to the drive pulse shaper 4, and in the drive pulse shaper 4, a drive voltage pulse based on the correction data is applied to each heating element.

FIG. 3(a) shows the case where the correction value is O and the pulse width of the driving pulse is maximum, and FIG. 3(b) shows the driving pulse when area correction is performed. .

Thereby, it is possible to perform correction appropriately corresponding to the thermal history state of each heating element 'C1 based on the area correction value.

[Problem to be solved by the invention]

However, in the energization control method described above, when counting the total number of energized dots for one row of each heat generating element, all the heat generating elements are counted and the energizing time is commonly calculated for each heat generating element. Since I am trying to control the
Even if the energization status of the upper heating element and the lower heating element of the thermal head are significantly different, the energization control will be performed uniformly throughout the thermal head. As a result, the energization control will be equal to the heating elements that were not energized, making it impossible to perform appropriate energization control for each heating element, and the peak temperature of each heating element will change, resulting in uneven printing. There is a problem that this occurs.

Furthermore, conventional thermal heads had heating elements of about 48 dots, but in recent years, there has been a trend toward higher density thermal heads, and for example, multi-dot heating elements with a large number of heating elements, such as 96 dots or 128 dots, have been used. 4 normal heads have been developed, and the above-mentioned problems have become particularly noticeable in the J3 thermal head with a large number of dots.

The present invention overcomes these problems in the conventional thermal head, maintains the peak temperature of each heating element constant, and provides energization control for a thermal head that can energize each heating element with appropriate energization energy. The purpose is to provide a method.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for controlling energization of four normal heads, in which a plurality of heating elements provided in a thermal head are energized while printing one line. A thermal head that counts the total number of dots and controls the energization energy to increase or decrease based on the total number of energized dots!II
In one method, each heating element of the thermal head is divided into a plurality of blocks;7. The total number of energized dots is counted for each of these blocks, and based on this total number of energized dots, increase/decrease correction data for the energization energy in the next energization cycle of the heating element is calculated, and based on this increase/decrease correction data, the It is characterized in that the energizing energy of each heating element is changed for each of the previous two blocks.

[For production]

According to the present invention configured as described above, each heating element is divided into a plurality of blocks, the total number of energized dots is counted for each block, and the energized energy is increased or decreased based on this total number of energized dots. Therefore, even if the energization state of each heating element of the thermal head is significantly different, it is possible to finely control the energization of each heating element according to the energization state, and as a result, the peak temperature of each heating element can be kept constant. It is possible to maintain good quality printing without uneven printing.

〔Example〕

Hereinafter, the present invention will be explained with reference to the drawings and examples.

FIG. 1 shows an embodiment of the energization control device for carrying out the energization control method for a thermal head according to the present invention.
... are formed in a straight line, and each of these heating cords 6
A power source 7 that applies a predetermined driving voltage is connected to the .

In addition, the MPU, which is a central processing unit for a personal computer, performs control.
8 is arranged, and this MPU 8 has a predetermined 0N1
Each heating element 6, 6, .
are connected to each other. In this embodiment, the zero two heating elements 613 and the energization time controller 9 are divided into blocks 10 for each of the three adjacent heating elements 6, 6, . . .
1 of each energization time controller 9 and the MPU 8
A dot counter 11 is connected to 7j, which counts the number of energized dots of each heating element 6 in each block 10 by iI based on the 0N10FF energization data from the MPU 8. Further, the dot counter 11 calculates the total number of energized dots by inputting the counted number of dots from the dot counter 11, and increases or decreases the energization time of the drive voltage to each heating cord 6 based on this number of energized dots. A correction calculator 12 is connected which calculates correction data and outputs it to each energization time controller i/roller 9 in the same block 10. When the number of energized dots is large, the energization time is decreased, and when the total number of energized dots is small, the energization time is increased. Then, each energization time controller 9 controls the correction computing unit 1.
Increase/decrease the energization time based on the increase/decrease correction data from 2.
II.

Next, the operation of this embodiment having the above-described configuration will be explained.

First, when printing the first line, the MPU 8 outputs 0N10FF data to each energization time controller 9, 9, . . . based on a desired print signal, and the energization time controller 9 controls each heating cord. power supply 7 for 6
By applying an eJTi pressure pulse for a predetermined period of time, a predetermined heating cord 6 is made to generate heat and is brought into pressure contact with the paper via the ink ribbon, thereby performing desired printing.

Then, for each tri block 10, the dot counter 11 sends 0N10 to each heating element 6, 6...
Input the FF'a electric data, count the number of energized dots, and output it to the correction calculator 12. When one line of printing is completed,
Each dot counter 11 is cleared and the number of dots printed in the next line is set to au.

When printing the next line, the MPU 8 outputs 0N10FF data to each energization time controller 9.9 based on the desired print signal, and the correction wave tEEB12 outputs 0N10FF data from the dot counter 11. The total number of energized dots is calculated based on the number of counted dots, and based on this number of energized dots, increase/decrease correction data for the energization time of the drive voltage to each heating element 6 is calculated, and this increase/decrease correction data is applied to each energization time in the same block 10. Output to time controller 9.

Then, the energization time controller 9 corrects the energization time based on the 1σ increase/decrease correction data, and uses the corrected energization time to energize a predetermined heating element 6 according to the 0N10FF data from the MPU 8. 6 to a temperature suitable for printing. By repeating such operations, appropriate energization control can be performed depending on the energization state of the previous row. .

In this way, in this embodiment, each heating element is 6°6...
- is divided into a plurality of blocks 10, the total number of energized dots is counted for each block 10, and the energization time is increased or decreased based on this total number of energized dots, so that the heat generation in the upper part of the thermal head 5 is reduced. Element 6 and lower heating element P6
Even if the energization state is significantly different from that of the heating element 6, the energization υ1@
can be done. As a result, the peak temperature of each heating element 6 can be kept constant, and proper printing without uneven printing can be performed.

Note that the present invention is not limited to the embodiments described above, and various changes can be made as necessary.

〔Effect of the invention〕

As explained above, in the thermal head energization control method according to the present invention, each heating element is divided into a plurality of blocks and the energization energy is controlled for each block. Even if the conditions are significantly different, it is possible to perform tight energization control for each heating element according to the energization state, and as a result, the peak temperature of each heating element can be maintained constant, reducing uneven printing. This has the effect that it is possible to perform printing with good quality.

4. Drawing 1! ! II$1 Explanation FIG. 1 is a block diagram showing an embodiment of an energization control device for carrying out the energization control method for a thermal head according to the present invention, and FIG. 2 is a block diagram showing a conventional energization control I neck mounting. , FIGS. 3(a) and 3(b) are diagrams showing the state of drive pulses without and with conventional area correction, respectively.

5... Thermal head, 6... Heating element, 8...
MPU, 9... Energization time controller, 10... Block, 11... Dot counter, 12... Correction?
Ttn device.

Figure 1

Claims (1)

[Claims] In a method for controlling energization of a thermal head, the total number of dots energized while printing one line on a plurality of heating elements provided in a thermal head is counted, and the energization energy is increased or decreased based on the total number of energized dots. , dividing each heating element of the thermal head into a plurality of blocks, and counting the total number of energized dots for each block;
Based on this total number of energized dots, the increase/decrease correction data of the energization energy in the next energization cycle of the heating element is calculated,
A method for controlling energization of a thermal head, characterized in that the energization energy of each of the heating elements is controlled for each of the blocks based on the increase/decrease correction data.