JP2644583B2 - Thermal head energization control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling energization of a thermal head, and in particular, corrects energization energy to a plurality of heating elements provided in the thermal head to perform proper printing. The present invention relates to a method for controlling the energization of a thermal head capable of performing the control.

[Conventional technology]

Generally, a thermal printer is provided with a thermal head in which a plurality of heating elements are linearly arranged, and a thermal transfer medium such as an ink ribbon or a thermal recording paper and a thermal head are perpendicularly aligned with respect to the direction in which the heating elements are aligned. While moving, printing is performed while controlling the energizing energy of each heating element.

Then, the present inventors count the number of energized dots among the heating elements of one row, and update the total energizing area of each of the heating elements for each energizing cycle of the heating elements based on the number of dots. Meanwhile, an energization control method has been proposed in which the magnitude of energization energy in the next energization cycle is adjusted based on the energization area to control the peak temperature of each heating element to be constant.

FIG. 2 schematically shows an energization control device for carrying out the energization control method. This energization control device counts the total number of energized dots for one row of each heating element (not shown) of the thermal head. Then, the total energized area of each heating element is grasped from the number of energized dots, and when the energized area exceeds a set value, the area correction calculator 1 which calculates and calculates the OFF time of the drive voltage pulse of each heating element is calculated. Have. The reference minimum OFF time for turning off the power supply to each heating element is input to the area correction calculator 1, and the area corrected OFF time and the minimum OFF time from the area correction calculator 1 are added. And an adder 2 for outputting the correction data as correction data. The adder 2 is connected to an OFF time register 3 for temporarily holding and outputting the correction data from the adder 2, and the OFF time register 3 has an OFF time based on the correction data. A drive pulse shaper 4 for forming a drive voltage pulse having a pulse width of a value obtained by subtracting the value of the drive pulse is connected.

In the energization control method by such an energization control device, first, the area correction arithmetic unit 1 counts the total number of energized dots of each heating element, obtains a predetermined area correction value, and outputs it to the adder 2. Then, the adder 2 adds the area correction value and the minimum OFF time to obtain O as correction data.
Output to FF time register 3. This OFF time register 3
Is temporarily output to the drive pulse shaper 4, and a drive voltage pulse based on the correction data is supplied to each heating element in the drive pulse shaper 4.

FIG. 3 (a) shows the case where the correction value is 0 and the pulse width of the drive pulse is the maximum, and FIG. 3 (b) shows the drive pulse when the area correction is performed. .

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

[Problems to be solved by the invention]

However, in the energization control method as described above, when counting the total number of energized dots for one row of each heating element, all heating elements are counted, and the energization time is commonly set for each heating element. Because the control is performed, even if the energization state of the upper heating element and the lower heating element of the thermal head is significantly different, the energization control is performed uniformly over the entire thermal head. In this case, the power supply control of the heating element that has been performed is equal to the power supply control of the heating element that has never been supplied with power. There has been a problem that printing unevenness occurs due to a change in temperature.

Further, the heat generating element of the conventional thermal head is about 48 dots, but in recent years, the thermal head tends to have a high density, for example, a multi-dot heat generating element such as 96 dots or 128 dots is formed. Thermal heads have been developed, and such problems have become particularly prominent in such multi-dot thermal heads.

SUMMARY OF THE INVENTION The present invention overcomes such problems in the prior art, maintains the peak temperature of each heating element constant, and controls the power supply of a thermal head that can supply power to each heating element with appropriate power supply energy. The aim is to provide a method.

[Means for solving the problem]

In order to achieve the above object, a method for controlling energization of a thermal head according to the present invention includes counting the total number of dots energized during printing of one line on a plurality of heating elements provided on the thermal head, and determining the total energization. In a method for controlling energization of a thermal head for increasing or decreasing energizing energy based on the number of dots, each heating element of the thermal head is divided into a plurality of blocks, and at least one upper-level block including the plurality of blocks is formed. The total number of energized dots is counted for each of these blocks and the upper block, and the energization energy increase / decrease correction data in the energization cycle of the next heating element is calculated based on the total number of energized dots. The respective increase / decrease correction data are sent to the respective blocks and the upper block, and the respective increase / decrease correction data are transmitted. It is characterized in that so as to control the excitation energy of the heating elements based on the data.

(Operation)

According to the present invention having the above-described configuration, each heating element is divided into a plurality of blocks, an upper block including the block is formed, and the total number of energized dots is counted for each of these blocks and each upper block. Since the energization energy is increased or decreased based on the total number of energized dots, even if the energization state between the upper heating element and the lower heating element of the thermal head is significantly different, each heating element is individually controlled. The energization control can be finely performed according to the energization state, and the energization control is performed based on increase / decrease correction data based on a small range energization state in each block of the heating elements and a wide range energization state in the upper block. Therefore, it is possible to perform appropriate correction according to the energized state of each heating element in various ranges. As a result, the peak temperature of each heating element can be kept constant, and printing of good quality without printing unevenness can be performed.

〔Example〕

 Hereinafter, the present invention will be described with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of an energization control device for implementing an energization control method for a thermal head according to the present invention. In a thermal head 5, a plurality of heating elements 6, 6,. A power supply 7 for applying a predetermined drive voltage is connected to each of the heating elements 6.

The MPU8, a central processing unit for personal computers that controls
In the MPU 8, energization time controllers 9, 9,... For independently controlling the energization time (energization energy) of each of the heating elements 6 based on predetermined ON / OFF energization data are provided. Each of the heating elements 6, 6,... Is connected. In the present embodiment, the heating element 6 and the energization time controller 9 are divided into small blocks 10a for each of the two heating elements 6, 6, and are further composed of three small blocks 10a, 10a. An upper large block 10c, which is composed of an upper middle block 10b and two middle blocks 10b, 10b, is formed.

Each energization time controller 9, 9 in each of the small blocks 10a
And the MPU 8 between each heating element 6 in each of the small blocks 10a based on ON / OFF energization data from the MPU 8.
Dot counter for small block counting the number of energized dots
11a are connected, and similarly, each energization time controller 9, 9 in the middle block 10b and the large block 1
0c between each energization controller 9,9 and the MPU8,
The middle block dot counter 11b and the large block dot counter 11c are connected to each other.

Further, the small block dot counter 11a includes:
The total number of energized dots is calculated by inputting the number of counted dots from the small block dot counter 11a, and correction data for increasing or decreasing the energizing time of the drive voltage to each heating element 6 is calculated based on the number of energized dots. A small block correction calculator 12a that outputs to each energization time controller 9 in the small block 10a is connected. Similarly, the middle block dot counter 11b and the large block dot counter 11c
In the middle block 10b and the large block 10c, the number of counted dots from the dot counters 11b and 11c for the middle block and the large block are inputted, and increase / decrease correction data is calculated.
The middle block correction calculator 12b and the large block correction calculator 12c that output to the respective energization time controllers 9 are connected to each other.

For each energizing time controller 9, each heating element 6, 10b, 10b, 10c counted by the small block dot counter 11a, the middle block dot counter 11b, and the large block dot counter 11c. The increase / decrease correction data from the correction calculators 12a, 12b, and 12c based on the number of energized dots 6 are respectively input.

In the present embodiment, each of the correction computing units 12a and 12a
The increase / decrease correction data by b and 12c reduces the energizing time when the total number of energized dots for the heating element 6 to be controlled in the previous line printing is large, and increases the energizing time when the total energized dot number is small. The power supply time is controlled to increase or decrease.

That is, in the present embodiment, when controlling the energization time of each heating element 6, the small block 10a of each heating element 6 is controlled.
The energization time of the heating element 6 to be controlled can be corrected in consideration of the energization state of the heating element 6 in the small range, the energization state of the middle range in the middle block 10b, and the energization state of a wide range in the large block 10c. When only some of the heating elements 6 are energized, the heat of the energized heating elements 6 is easily radiated, so that the number of energized dots in the heating elements of the small blocks 10a is large. However, if the number of energized dots in the middle block 10b or the large block 10c is small, the energizing time of the heating element 6 in the small block 10a is not set to be extremely short, and the energizing time should be appropriately corrected. Can be.

Each of the small blocks 10a has a small block 10a.
May be divided so that the number of the heating elements 6 included in each of the blocks may be three or more.
And each lower block 10a, 1 included in the large block 10c
The number of 0b may be set to any number. Further, in the present embodiment, the small, medium, and large blocks 10a, 10b, and 10c have a three-stage block configuration, but the blocks 10a, 10b, and
10c may be formed in more stages.

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

First, when printing the first line, the MPU 8 outputs ON / OFF data to each of the energization time controllers 9, 9... Based on a desired print signal. By supplying a drive voltage pulse from the power supply 7 to the power supply 7 for a predetermined time,
Is heated and pressed against the paper via the ink ribbon to perform desired printing. Then, each of the heat generating elements 6, 6,.
FF energization data is input, the number of energization dots is counted and output to each of the correction computing units 12a, 12b, 12c, and when printing of one line is completed, the dot counters 11a, 11b, 11c are cleared. The counting in the printing of the next line is started.

When printing the next line, ON / OFF data is supplied from the MPU 8 based on the desired print signal to each energization time controller.
9, 9... And the correction energizers 12a, 12b, 12c calculate the total energized dot count from the counted dot counts from the dot counters 11a, 11b, 11c, based on the energized dot count. Calculate the increase / decrease correction data of the energization time of the drive voltage to each heating element 6 and output this increase / decrease correction data to each energization time controller 9, 9,.

The energization time controller 9 controls the small block 10a, the middle block 10b, and the large block 10c, respectively.
The energization time is corrected based on the increase / decrease correction data from each of the correction calculators 12a, 12b, and 12c corresponding to the above, and the predetermined heating element 6 is energized in accordance with the ON / OFF data from the MPU 8 by the corrected energization time. It has been made to be. By repeating such an operation, the heating elements 6 in the previous row are formed.
Appropriate energization control can be performed according to the energization state of the heater element 6 of the adjacent block.

As described above, in the present embodiment, each of the heating elements 6, 6,... Is divided into a plurality of small blocks 10a, and the middle block 10b including the small blocks 10a and the middle block 10b.
Are formed, and the total number of energized dots is counted for each of these blocks 10a, 10b, 10c.
Since the energization time is corrected to increase or decrease based on the total number of energized dots, even if the energization state between the upper heating element 6 and the lower heating element 6 of the thermal head 5 is significantly different, each heating element 6 Thus, the energization control can be finely performed according to the energization state. Moreover, increase / decrease correction data based on the small-area energized state in the small block 10a of each heating element 6, the medium-range energized state in the middle block 10b, and the wide-area energized state in the large block 10c are sent to the energized time controllers 9, 9,. Since the power is sent, the power-on time can be controlled according to the power-on state of each heating element 6 in various ranges, and more appropriate correction can be performed. As a result, the peak temperature of each heating element 6 can be kept constant, and good quality printing without uneven printing can be performed.

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

〔The invention's effect〕

As described above, the energization control method for the thermal head according to the present invention is configured to correct the energization energy for each of the plurality of blocks and the upper blocks into which each heating element is divided. Even when the energization state is significantly different, it is possible to finely control the energization of each heating element according to its energization state, and based on a small range energization state in each block and a wide range energization state in the upper block. Thus, it is possible to perform an appropriate correction according to the energized state of each heating element in various ranges. As a result, it is possible to maintain the peak temperature of each heating element at a constant level, and to perform printing of good quality without printing unevenness.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an energization control device for implementing an energization control method for a thermal head according to the present invention, FIG. 2 is a block diagram showing a conventional energization control device, and FIG. FIGS. 4B and 4B are diagrams showing driving pulse states when there is no conventional area correction and when there is a conventional area correction. 5 ... thermal head, 6 ... heating element, 8 ... MPU,
9 ... energization time controller, 10a ... small block, 10b
… Medium block, 10c… Large block, 11… Dot counter, 12… Correction calculator.

Claims (1)

(57) [Claims] A thermal head which counts the number of dots applied to a plurality of heating elements provided in a thermal head during printing of one line, and controls the energization energy based on the total number of dots. In the energization control method, each heating element of the thermal head is divided into a plurality of blocks, and at least one upper-level block including the plurality of blocks is formed. The total number of energized dots is counted, and the increase / decrease correction data of the energization energy in the energization cycle of the next heating element is calculated based on the total number of energized dots. To control the energization energy of each of the heating elements based on the respective increase / decrease correction data. Energization control method for a thermal head is characterized in that the.