JPH0725175B2 - Thermal head - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermal head used in a thermal transfer printer or the like.

(B) Conventional Technology FIG. 2 is a plan view of a main part of a conventional thermal head.

In this thermal head, for example, a heating resistor film is provided on an upper surface of an alumina ceramic substrate (insulating substrate) 1 to form a heating resistor layer 2, and each heating resistor pair of the heating resistor layer 2 is formed.
A common lead pattern (common electrode) 3 and an individual lead pattern (individual electrode) 4 are formed on both sides of the bottom of 2a,
A protective film is formed on the surfaces of the substrate 1, the heating resistor layer 2, and the lead patterns 3 and 4.

The thermal head applies a pulse voltage between the lead patterns (individual electrode and common electrode) 3 and 4 to generate a heating resistor pair 2a.
Information is printed on the recording paper that is pressure-contact-fed in a superposed state with the heat-sensitive paper (heat-sensitive ribbon) with respect to the heat-generating resistor pair 2a by selectively generating heat.

(C) Problems to be Solved by the Invention In the above-mentioned line-type thermal head (a head in which a large number of heating dots are arranged in parallel at one end of the insulating substrate), lead patterns are formed on both sides of the hem of the heating resistor pair. I am doing it. That is, the individual lead pattern is arranged on one end side of the heating resistor pair, and the common lead pattern is arranged on the other end side. Therefore, the common lead pattern having a constant width is located between the other end of the heating resistor pair and the edge of the insulating substrate. For this reason, there is a disadvantage that the heating resistor pair cannot be arranged (adjacently arranged) in alignment with one edge of the insulating substrate.

Further, in this thermal head, the individual lead patterns and the common lead patterns face each other, and the individual lead patterns and the common lead patterns are alternately arranged in sequence.
Therefore, on both sides of the individual lead pattern, a pair of two heating resistors whose outer sides are partitioned by the common lead pattern are located. Therefore, when probing the heating resistor (probe pins are set on the individual lead pattern and the common lead pattern to measure or trim the resistance value), two pairs of resistors located on both sides of the individual lead pattern are paired. The resistance values of the heating resistors (1 dot for printing) are simultaneously measured (the resistance values of the pair of heating resistors are measured in a combined state). Therefore, since the resistance value of each heating resistor cannot be measured separately and trimming for adjusting the resistance value of each heating resistor cannot be performed individually, if the resistance values of the pair of heating resistors are different from each other. Have disadvantages such as poor print quality.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a thermal head that is capable of uniformly trimming the resistance value of a heating resistor and that is small in size and has good printing quality.

(D) Means and Actions for Solving the Problem In order to achieve this object, the thermal head of the present invention has the following configuration.

The thermal head has heating resistors arranged in parallel to the end of the upper surface of the insulating substrate, and individual lead patterns and independent divided common lead patterns are alternately arranged in parallel to the heating resistors in an orthogonal direction, The heating resistor located between the individual lead patterns and the divided common lead patterns independent of each other is trimmed, and thereafter, the lower end portions of the plurality of independent divided common patterns are made common.

In the thermal head having such a configuration, the heating resistors are arranged in parallel to one end edge of the insulating substrate, and the individual lead patterns and the independent divided common lead patterns are respectively arranged in the direction orthogonal to the heating resistors. , And is arranged in the direction of the other edge of the substrate. Therefore, since there is no lead pattern between the one edge of the insulating substrate and the heat generating resistor, the heat generating resistor can be aligned with the one edge of the insulating substrate. As a result, a complete so-called real edge type head can be obtained, and a small head can be realized.

Further, in this thermal head, the common electrode, which is originally in common, is divided into individual divided common lead patterns, and the divided common lead patterns and the individual lead patterns are alternately arranged in parallel. Therefore,
On both sides of the individual lead patterns, a pair of two heating resistors whose outer sides are partitioned by common lead patterns are located. Probing (measurement of the resistance value of the heating resistor, trimming) is performed in this state (in the state where a plurality of divided common lead patterns are independent). In other words, the probe pins are set up on the individual lead pattern and the divided common lead pattern which are adjacent to each other via the heating resistor, and this is executed.
Thereby, it is possible to measure the respective resistance values of the heating resistors (one dot at the time of printing) located on both sides of the individual lead pattern, and it is possible to uniformly trim each heating resistor. After the trimming process, a common electrode pattern is formed by a conductive paste on the lower ends of the plurality of divided common lead patterns to be common to each other.

(E) Embodiment FIG. 1 is a plan view of a principal part showing a specific embodiment of the thermal head according to the present invention.

As is well known, the thermal head has a line-shaped heat generating resistor layer 2 formed at an end of the upper surface of an alumina ceramic substrate (insulating substrate) 1, and each of the heat generating resistor layers 2 has a divided common lead pattern 3 and An individual lead pattern (individual electrode) 4 is formed, and a protective film (not shown) is formed on the surface of the substrate 1, the heating resistor layer 2, and the lead patterns 3 and 4. In the embodiment, a thick film line head is shown.

The feature of the present invention is that the common electrode which is originally common in common is divided into a plurality of divided common lead patterns 3 which are independent of each other, and the divided common lead patterns 3 and the individual lead patterns 4 are alternately arranged in parallel. It is in.

The heating resistor layer 2 is arranged in parallel with one end edge of the insulating substrate 1, and the individual lead patterns 4 and the divided common lead patterns 3 are orthogonal to the heating resistor layer 2 in the insulating substrate 1.
The pattern is formed in the direction of the other end edge of the drawing. The individual lead patterns 4 and the divided common lead patterns 3 are alternately arranged in parallel at regular intervals. Further, the divided common lead pattern 3 is set to be longer than the drawing length of the individual lead pattern 4. Therefore, the heating resistor 21 is positioned between the individual lead patterns 4 and the divided common lead pattern 3 which are alternately arranged. In this state, the plurality of divided common lead patterns 3 are in independent states. That is, the heating resistor 21 between the individual lead pattern 4 and the divided common lead pattern 3 is set to be probable (measurement of resistance value and trimming).

After the probing (trimming) of each heating resistor 21 is completed, the lower end portion (lead-out end portion) of each divided common lead pattern 3 is made common. That is, the common electrode pattern 31 is formed on the lower end portion of each divided common lead pattern 3 by using a conductive paste such as silver paste so as to be shared.

In the thermal head having such a configuration, the heating resistor layer 2 is arranged in parallel with one end edge of the insulating substrate 1,
The individual lead patterns 4 and the independent divided common lead patterns 3 are arranged in the direction orthogonal to the heating resistor layer 2 and in the direction of the other edge of the substrate 1. Therefore,
Since there is no lead pattern (common electrode) between one end edge of the insulating substrate 1 and the heat generating resistor layer 2, the heat generating resistor layer 2 should be arranged (adjacent to) the one edge of the insulating substrate 1. Can be done. As a result, a complete so-called real edge type head can be obtained, and the size of the head itself can be reduced.

Further, originally, the common electrode, which is originally in a common shape, is divided into individual divided common lead patterns 3, and the divided lead patterns 3 and the individual lead patterns 4 are separately formed.
And are alternated in parallel. Therefore, on both sides of the individual lead pattern 4, a pair of two heating resistors 21, 21 (heating resistor pair 2
a) is located. When probing (measurement of the resistance value of the heating resistor and trimming) is performed, the plurality of divided common lead patterns 3 are performed independently. That is, the probe pins are set up on the individual lead pattern 4 and the divided common lead pattern 3 which are adjacent to each other with the heating resistor 21 interposed therebetween. As a result, the heating resistors located on both sides of the individual lead pattern 4 (when printing,
It is possible to measure the resistance value of each one dot) 21 and 21, respectively, and it is possible to uniformly trim each heating resistor 21. After this trimming process, the pull-out lower end portions of the plurality of divided common lead patterns 3 are made common.

In this way, it is possible to realize a compact thermal head with uniform print quality.

(F) Effect of the Invention According to the present invention, as described above, the heating resistor is arranged in parallel with the end portion of the upper surface of the insulating substrate, and the individual lead pattern and the independent divided common are provided in the direction orthogonal to the heating resistor. The lead patterns are alternately arranged in parallel to trim the heating resistor located between the individual lead patterns and the divided common lead patterns independent of each other, and then the lower end portions of the plurality of independent divided common patterns are shared. Therefore, the heat generating resistor can be arranged close to the edge of the substrate, the recording paper does not come into contact with the common pattern, the paper feeding is smooth, and a small head having a long head life can be provided. Further, since the resistance value of each heating resistor can be trimmed separately, the printing quality is improved, and the excellent effects of achieving the object of the invention are achieved.

[Brief description of drawings]

FIG. 1 is a plan view of relevant parts showing a thermal head of an embodiment, and FIG. 2 is a plan view of relevant parts of a conventional thermal head. 1: Insulating substrate, 2: Heating resistor layer, 2a: Heating resistor pair, 3: Separated common lead pattern, 4: Individual lead pattern, 21: Heating resistor, 31: Common electrode pattern.

Claims (1)

[Claims] 1. A heating resistor is arranged in parallel with an end portion of an upper surface of an insulating substrate, and individual lead patterns and independent divided common lead patterns are alternately arranged in parallel in a direction orthogonal to the heating resistor. A thermal head in which a heating resistor located between an individual lead pattern and a divided common lead pattern is trimmed, and then the lower end portions of the plurality of independent divided common patterns are shared.