JPS61192570A - Method for controlling heating of thermal head - Google Patents

Abstract

PURPOSE:To enable recording with uniform density, by a method wherein one of heat generators is set as a count dot and the heat accumulation quantity of a thermal head is calculated as a ratio occupied by ones generating heat in dot patterns and the power applied to the thermal head is controlled corresponding to said heat accumulation quantity. CONSTITUTION:For example, 24 heat generators are arranged to a thermal head in a line and, when the thermal head performs 24-step movement, 24X24 dot patterns are formed and the heat generators are selectively heated in each step. A head driving means 20 applies power to the thermal head 10 to drive said head 1. A counter 30 counts the number of count dots generating heat during printing operation and a heating control means 40 calculates a ratio occupied by ones generating heat among count dots 121-1224 on the basis of the signal from the counter 30 and this ratio is set as the ratio occupied by the dots generating heat in 24X24 dot patterns to calculate the heat accumulation amount of the head. A control signal for controlling applied output outputted by the head driving means 20 is generated on the basis of the calculated heat accumulation quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heating control method for a heat generating head used in a thermal printer or a thermal transfer printer.

More specifically, a heating head with a plurality of heating elements arranged in a row is used, and the heating head is moved stepwise in a direction intersecting the arrangement direction of the heating elements, and the heating elements are selectively placed in each step. The present invention relates to a heating control method for a heat generating head that performs printing by heating.

[Conventional technology]

In thermal printers or thermal transfer printers, due to the heat storage effect of the heat-generating head, even if a certain printing power is applied to the heat-generating head, the temperature of the heat-generating head will vary between when printing at the beginning of a line and when printing at the end of a line. different. For this reason, there was a problem that the print density became non-uniform.

Conventionally, as a method to solve such problems,
For example, when a heating head with 24 heating elements arranged is used and a 24 x 24 pattern is printed by moving the heating head stepwise in a direction perpendicular to the direction in which the heating elements are arranged (24 steps after moving),
There has been a system in which the number of dots that generate heat in this dot pattern is counted, and the printing power to the heat generating head is reduced in accordance with the count value.

[Problem that the invention seeks to solve]

However, the above method has the problem that it takes a long time to compensate for the applied power because it is necessary to count the number of dots that generate heat for all 24 x 24 dots, which in turn slows down the printing speed. Ta.

The present invention has been made in order to eliminate the above-mentioned problems, and an object of the present invention is to realize a heating control method for a heat-generating head that can compensate for the applied power in a short time and obtain recording with uniform density at high speed. do.

[Means for solving problems]

The present invention uses a heating head in which a plurality of heating elements are arranged in a line, moves the heating head in steps in a direction intersecting the direction in which the heating elements are arranged, and selectively heats the heating elements at each step. In a heating control method for a heating head that performs printing, one of the heating elements is set as a count dot according to the step of the heating head, and when the heating element has moved a predetermined number of steps, all the count dots are set. The amount of heat stored in the heating head is determined by taking the proportion of the generated heat in the dots of all the dots of the dot pattern formed by the movement of the predetermined number of steps, and calculates the amount of heat stored in the heating head, and This is a heating control method for a heat-generating head, characterized in that the power applied to the heat-generating head is controlled.

〔Example〕

The present invention will be explained below with reference to the drawings.

FIG. 1 is a block diagram showing an example of a device for implementing the method according to the present invention.

In FIG. 1, 10 is a heat generating head, 20 is a head driving means, 30 is a counter, and 4o is a heating control means.

In the heat generating head 10, for example, 24 heat generating elements are arranged in a line. The heating head 1G moves stepwise in a direction perpendicular to the direction in which the heating elements are arranged.

When the heat generating head 10 moves 24 steps, 24×24
A pattern of do and g is formed. At each step the heating element is selectively heated. A second dot pattern like this
As shown in the figure. If we empty one row of heating elements with this dot pattern, each column will have a dot, ) 121
-1224 are provided one by one. The arrangement of these count dots 121 to 1224 has a regularity as shown in FIG. 2, for example. Calantho,
) The exothermic conditions 121 to 1224 are representative of the exothermic conditions of the column to which they belong.

The head driving means 20 applies applied power to the heat generating head 1o to drive it.

The counter 30 counts the number of count dots that are generating heat during printing operations. This counting is performed, for example, after the heat generating head 10 has moved 24 steps.

Based on the signal from the counter 30, the heating control means 40 determines the proportion of heat generating components among the currents (121 to 1224), and converts this proportion into 24
The amount of heat stored in the head is calculated as the proportion of dots that generate heat in the pattern of 24 dots and dots.

Then, based on the calculated heat storage amount, a control signal for controlling the applied power output by the head driving means 20 is generated.

Next, the operation of such a device will be explained.

The case where the dots in the KQ portion are heated as shown in FIG. 3 will be explained.

In this case, among count dots 121 to 1224, 1213 and 1214 generate heat, so the proportion of count dots that generate heat is as follows.

Since the heat generation state of each count dot is representative of the heat generation state of the column to which it belongs, this ratio is
The amount of heat storage is determined as the proportion of dots generating heat in a 24×24 dot pattern. Then, the printing power is compensated based on this amount of heat storage.

The time course of the compensated applied power is shown in FIG. In the graph of FIG. 4, the vertical axis shows the applied voltage and the horizontal axis shows the time.

As shown in this graph VC, in order to prevent the head temperature from rising due to heat accumulation, the applied power is reduced over time. gram a1 to 82).

On the other hand, the proportion of dots that actually generate heat in the 24×24 dot pattern matches the proportion calculated from only the counted dots.

Incidentally, the arrangement of the count dots may be other than the arrangement shown in FIG. 2, for example, the positions may be designated by random numbers and arranged in a circular pattern.

Further, the heat generating head 10 may be provided with a number of heat generating elements 11 other than 24.

Furthermore, the heat generating head 10 may move in a direction intersecting the arrangement direction of the heat generating elements 11.

Also, the count of the heated count dot is 24
The process may be performed every time a pattern other than 24 Do and G is formed.

〔effect〕

According to the method according to the present invention, the following effects can be obtained.

Using a probabilistic method, the amount of heat storage is determined from the proportion of heat generated in the count dots representing each column, and the applied power is compensated according to this amount of heat storage. For this reason,
There is no need to count all the heating elements that actually generate heat. Thereby, the applied power can be compensated in a short time, and recording with uniform density can be obtained at high speed.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an example of a device for implementing the method according to the present invention, and Fig. 2 is a diagram showing an example of a dot pattern formed by the movement of the heating head. 3 and 4 are explanatory diagrams of the operation of the apparatus shown in FIG. 1. 10...Heating head, 11...Heating element, 121-1
224...Count dot, 20...Head drive means, 30...Counter, 40...Heating control means. Figure 1 Figure 2 12゜

Claims (1)

[Claims] Using a heating head in which a plurality of heating elements are arranged in a row,
In a heating control method for a heat generating head, the heat generating head is moved stepwise in a direction intersecting the arrangement direction of the heat generating elements, and printing is performed by selectively heating the heat generating elements at each step, according to the step of the heat generating head. One of the heating elements
When the heating element has moved a predetermined number of steps, the proportion of the number of counted dots that generate heat is calculated as the proportion of all the dots in the dot pattern formed by the movement of the predetermined number of steps. A heating control method for a heat-generating head, characterized in that the amount of heat stored in the heat-generating head is determined as a proportion of the heat generated in the heat-generating head, and the power applied to the heat-generating head is controlled according to the amount of heat stored.