JPH11334127A - Method for trimming thermal print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen a change amount of a resistance value and shorten a trimming time by trimming each heater element with using each resistance value to be smoothed as a target resistance value when each resistance value satisfies a predetermined criterion. SOLUTION: Since a target ±0.9% is not satisfied, a smoothing degree is increased by a preliminarily set increase. Smoothing is carried out with a smoothing degree 100 (S4). In consequence, a resistance value variation becomes +0.89%, -0.88%. Whether or not the resistance value variation resulting from the smoothing reaches the target is Judged (S3). A resistance value distribution obtained with the smoothing degree 100 reaches the target resistance value variation, and therefore the smoothing process is terminated (S5). A resistance value 413.8 Ω for changing a minimum resistance value 4137.9 Ω of an initial resistance value distribution by 100% is subtracted from each value of the resistance value distribution selected with the degree 100 and set as a target resistance value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention determines a target resistance value for each heater element of a heater element array formed on a substrate, and trims each heater element so as to match the target resistance value. The present invention relates to a method for trimming a thermal print head.

[0002]

2. Description of the Related Art In general, in a thermal transfer recording system, each heater element of a thermal print head is uniformly heated so that electric power is efficiently used as transfer energy, and a printed image looks natural to human eyes. It is desired that there is no density unevenness.

However, in a heater element array of a line thermal print head particularly using a thick film, the resistance value distribution of each heater element tends to be non-uniform, so that streak-like discontinuous lines or streaks in the recording direction are generated. Density unevenness may be formed.

In order to minimize the variation in the resistance value of the heater element array in such a thermal print head and to prevent the occurrence of discontinuous lines and uneven density, the resistance value of each heater element in the heater element array has conventionally been reduced. Measure and subtract the value from the minimum resistance value by a certain ratio determined according to the product specifications to determine the target resistance value, and trim the resistance value of each heater element to this target resistance value. Have been done.

[0005] However, if trimming is performed by setting the target resistance value based on the minimum resistance value of the entire heater element as described above, the resistance change amount of each heater element becomes too large, and the thermal printing is performed. There is a problem that the life of the head is deteriorated and the trimming operation takes too much time.

[0006]

As described above, in order to reduce the variation in the resistance value of the heater element array of the thermal print head, the target resistance value to be trimmed is set to the minimum resistance value of the entire original heater element. If the trimming is performed with the heater element having a value as a reference, the amount of change in resistance of each heater element becomes too large, and the life of the thermal print head is deteriorated, and the trimming operation takes too much time.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and provides a method of trimming a thermal print head which has a small amount of change in resistance value, and therefore has a short life degradation and a short trimming time. With the goal.

Another object of the present invention is to provide a method for trimming a thermal print head that can perform efficient trimming within an allowable range of a resistance value change according to product specifications.

[0009]

According to a first aspect of the present invention, there is provided a method for trimming a thermal print head, wherein a target resistance value is determined for each heater element of a heater element array formed on a substrate, and the target resistance value coincides with the target resistance value. In the thermal print head trimming method for trimming each heater element, a smoothing order smaller than the number of heater elements in the entire heater element array is set, and a target resistance value of each heater element is set to each heater element. The resistance of each heater element is set so that the average resistance value of the heater element rows equal to the smoothing order starting from the heater element in the element itself or in the vicinity of the heater element (about one or several heater elements) is used. Smoothing the value data When the resistance value smoothed satisfies a predetermined criterion, characterized in that trimming of the respective heater elements of the respective resistance values as the target resistance value.

According to a second aspect of the present invention, there is provided a thermal print head trimming method, wherein a target resistance value is determined for each heater element of a heater element array formed on a substrate, and each of the heaters is adjusted so as to match the target resistance value. In a method for trimming a thermal print head for trimming an element, a formula (ΣR _{i + j-1} -ΣR _i-1 ) / j (1) (where i is a resistor of 1 to n (n is a positive integer)) number,
j is a smoothing order where n> j (j is a positive integer). same as below. ), The resistance value data of each heater element is smoothed, and when each smoothed resistance value satisfies a predetermined criterion, the respective heater elements are trimmed with the respective resistance values as target resistance values. Features.

According to a third aspect of the present invention, in the thermal print head trimming method, a target resistance value is determined for each heater element of the heater element array formed on the substrate, and each of the heaters is adjusted so as to match the target resistance value. In a method of trimming a thermal print head for trimming an element, a formula (ΣR _{i + j−1} −ΣR _i-1 ) / j (1) (where i is a resistor of 1 to n (n is a positive integer)) number,
j is a smoothing order where n> j (j is a positive integer). same as below. ), The resistance value data of each heater element is smoothed. When each smoothed resistance value satisfies a predetermined criterion, the resistance value is determined in advance from the viewpoint of resistance value stabilization and prevention of breakage of the heater element. Each of the heater elements is trimmed by using a value obtained by subtracting a resistance change amount determined according to product specifications as a target resistance value.

As a result of the trimming, the resistance value decreases,
The smoothing of the present invention is desirably performed in a range where the initial minimum resistance value of the heater element array is reduced by 4 to 20%.

Generally, the smoothing is performed a plurality of times while increasing the smoothing order j until a predetermined criterion is satisfied.

(Operation) In the present invention, the smoothing order is set without using the average value of the resistance values of all the heater elements to determine the target resistance value of the heater element, and the heater of the number of the smoothing order is set. The resistance values of the elements are averaged to obtain a target resistance value.

Since the smoothing order is smaller than the total number n of the heater elements, the amount of change in resistance is smaller than the case where trimming is performed using the average value of the resistance values of the respective heater elements, and the time required for trimming is also shorter. Shorter.

Also, smoothing is started from a lower order, and if the resistance value distribution after the smoothing process does not satisfy a predetermined criterion, the smoothing order is increased and smoothing is performed again. When the target resistance value is obtained, the required smoothing can be performed with the minimum resistance value change.

In the present invention, the average resistance value is calculated from the sum of the resistance values of the heater elements of the order, and is set as the target resistance value.

Usually, the average resistance value represented by the equation (1) is
The target resistance value of the heater element of the resistor number k (where i <k ≦ i + j−1) is set. At the end of the heater element array, when it is not possible to ΣR i _{+ j-1} is, ΣR i _{+ j-1} is obtained by, for example, follow a resistor number reversed.

Further, if necessary, the resistance value of each heater element in the resistance value distribution obtained by the above-described smoothing operation is set in advance in accordance with the product specification from the viewpoint of resistance value stability and prevention of breakage of the heater element. If the value obtained by subtracting the minimum amount of resistance change necessary for stabilizing the resistance value is trimmed as a target resistance value distribution, the original desired resistance value distribution is obtained by use, so that deterioration over time can be avoided. it can.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a flowchart showing a main process of a method for trimming a thermal print head according to the present invention.

This embodiment has a total d of 5.6 dots / mm.
For a thermal print head having an ot number of 448 dots and an average resistance value of 4185.6 Ω, the target resistance value variation is ± 0.9%, and the resistance change amount for stabilizing the resistance is 4%.
This was performed at a setting of 13.8Ω.

First, the resistance value of the entire heater element array of the thermal print head was measured to determine the resistance value variation (step 1).

The resistance value variation is + 1.48%, -1.1
4%. Since this variation deviated from the target resistance value variation, smoothing was performed with a preset order (set to 60 in this embodiment) (step 2). As a result, the resistance value variation was + 1.05%,
0.95%.

From FIG. 1, it was determined whether or not the variation in the resistance value obtained by the smoothing has reached the target (step 3). However, since it has not yet reached ± 0.9%, the order was increased by a preset increment (set to 20 in this embodiment) (step 4), and smoothing was performed with the smoothing order 80 (step 2).

As a result, the resistance value variation is +0.96,
-0.91%.

Here, it was again determined from FIG. 1 whether or not the variation in the resistance value obtained by the smoothing has reached the target (step 3).

However, since it has not yet reached the target of ± 0.9%, the smoothing order was increased by a predetermined increment and smoothing was performed at the smoothing order of 100 (step 4). As a result, the resistance value variation is +
0.89% and -0.88%. From FIG. 1, it was determined whether or not the resistance value variation obtained by smoothing reached the target (step 3).

Since the resistance distribution obtained by the smoothing order 100 has reached the target resistance value variation, the smoothing process is terminated (step 5).

Here, the amount of change for stabilizing the target resistance value was taken into account as follows.

That is, in this embodiment, a resistance value of 413.8Ω for changing the minimum resistance value 4137.9Ω of the initial resistance value distribution by 100% is subtracted from each value of the resistance value distribution selected by the smoothing order 100. Was set as the target resistance value. The target resistance value of each heater element is obtained by the following equation.

[0032] FIG. 2 shows the resistance value distribution of the heater element at the beginning of this embodiment and after each smoothing. In FIG. 2, A represents the initial resistance value distribution, and B represents the resistance value distribution of A with the order 60. C is a resistance value distribution obtained by smoothing the resistance value distribution of A by order 80, and D is A by order 100
Resistance distribution obtained by smoothing with
E is a target resistance distribution obtained by subtracting 413.8Ω from each resistance of D.

After the target resistance value of each heater element was obtained in this manner, trimming was performed by a known method.

[0034]

According to the present invention, it is possible to realize a method of trimming a thermal print head which can set a target resistance value according to product specifications without causing density unevenness with a minimum resistance value change. The trimming time can also be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a target resistance value setting trimming method according to an embodiment of the present invention.

FIG. 2 is a graph showing an initial resistance value and a resistance value distribution of a heater element array of a thermal print head obtained according to the present invention.

Claims (5)

[Claims] A method for trimming a thermal print head, wherein a target resistance value is determined for each heater element of a heater element array formed on a substrate, and the respective heater elements are trimmed so as to match the target resistance value. In the above, the number of smoothing orders smaller than the number of heater elements of the entire heater element array is set, and the target resistance value of each heater element is set to the smoothing order starting from each heater element itself or a heater element near the heater element. The resistance value data of each heater element is smoothed so as to have an average resistance value of the heater element rows of the same number as the above, and when each smoothed resistance value satisfies a predetermined criterion, the resistance value is set to a target resistance value. Of each heater element Trimming method for the thermal printhead and performs ranging. 2. A method of trimming a thermal print head, wherein a target resistance value is determined for each heater element of a heater element array formed on a substrate, and the respective heater elements are trimmed so as to match the target resistance value. In the formula, (ΣR _{i + j-1} -ΣR _i-1 ) / j (1) (where i is a resistor number of 1 to n (n is a positive integer),
j is a smoothing order where n> j (j is a positive integer). same as below. ), The resistance value data of each heater element is smoothed, and when each smoothed resistance value satisfies a predetermined criterion, the respective heater elements are trimmed with the respective resistance values as target resistance values. Characteristic thermal printhead trimming method. 3. A method for trimming a thermal print head, wherein a target resistance value is determined for each heater element of a heater element array formed on a substrate, and the respective heater elements are trimmed so as to match the target resistance value. In the formula, (ΣR _{i + j-1} -ΣR _i-1 ) / j (where i is a resistor number of _{1 to} n (n is a positive integer),
j is a smoothing order where n> j (j is a positive integer). same as below. ), The resistance value data of each heater element is smoothed. When each smoothed resistance value satisfies a predetermined criterion, the resistance value is determined in advance from the viewpoint of resistance value stabilization and prevention of breakage of the heater element. A method for trimming a thermal print head, wherein each heater element is trimmed with a target resistance value obtained by subtracting a resistance change amount determined according to product specifications. 4. The thermal print head trimming method according to claim 1, wherein the smoothing is performed in a range where the initial minimum resistance value of the heater element array is reduced by 4 to 20%. 5. The method according to claim 1, wherein the smoothing is performed a plurality of times while increasing the smoothing order j until a predetermined criterion is satisfied.