JPH05278245A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain a thermal head in which the reaction of a substrate material with a glazing material at the time of burning is prevented for preventing the increase of a glazing width and ensuring a uniform heating element forming surface. CONSTITUTION:On the top surface of an alumina ceramic substrate 11, a reaction preventive layer (barrier layer) 12 is formed. On the top surface of the reaction preventive layer 12, a glaze layer 13 is formed. A heating element 14 is provided all over the reaction preventive layer 12 and the glaze layer 13. On the top surface of the heating element 14, electrodes 15 are formed, and on the surface thereof, a protective film 16 is provided. The reaction preventive layer 12 provided between the substrate 11 and the glaze layer 13 is a SiO2 film provided by a vacuum deposition method, a sputtering method, a coating-burning method, or the like. This film prevents the reaction of a substrate material with a glazing material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head.

[0002]

2. Description of the Related Art A thermal head in which a partial glaze is formed on a substrate and a heating element is formed on the partial glaze has improved heat generation efficiency, and a paper in the heating element portion is used for the thermal head by the entire glaze. It is known that the hitting property is improved and the printing quality is improved.

Particularly for low smoothness paper (Beck smoothness of 100 seconds or less), as shown in FIG.
By using the thermal head having the two-stage partial glaze 2 formed thereon, the paper contact property of the heating element 3 portion is further improved, and good printing is obtained.

Further, in the case of the general arc-shaped partial glaze head shown in FIG. 3B, the heat contact of the heating element 3 is as good as that of the partial glaze of the above two-stage structure, and it is good for low smoothness paper. Attempts have been made to reduce the curvature of the partial glaze 2 in order to obtain a print.

[0005]

However, FIG. 3A
The 2-step structure partial glaze composes the manufacturing process by forming a normal arc-shaped partial glaze and then etching the glaze layer, which increases the cost of the thermal head and also the printing durability of the thermal head. There may be problems on the top.

Further, as a method for reducing the curvature of the usual arc-shaped partial glaze of FIG. 3B, although it can be produced at a trial level by etching or machining, the conventional manufacturing technique of printing and firing glass paste is used. It was very difficult to manufacture at mass production level, and the width of partial glaze was usually limited to about 0.5 mm.

The cause is that the glass glaze layer 2 is directly formed on the ceramic substrate 1 as shown in FIG. 4A. In this structure, the ceramic of the substrate material and the glass of the glaze material react with each other during firing, causing a phenomenon in which the glass irregularly flows from the printed edge 2a, and the glaze width is expanded as shown in FIG. 4A. In addition, there is a problem that the edge portion 2a of the glass glaze 2 has an irregular shape which is considered to be affected by the nonuniformity of the surface condition of the substrate as exaggeratedly shown in FIG. 4B.

If the glaze width is increased, it cannot be used for low-smoothness paper, and the irregular shape of the glaze width causes unevenness on the heating element forming surface of the glaze layer 2 and, for example, heat generation at the wide position a in FIG. 4B. The body forming surface 3a is lower than the heat generating body forming surface 3b at the narrow position b, which prevents uniform contact of each heating element with the thermal paper or the ink ribbon, and variations in the temperature of the heating element due to difference in heat storage. There is a problem that is a cause of print quality deterioration.

The present invention has been made in view of such a problem in forming a normal arc-shaped glaze, and by preventing the reaction between the substrate material and the glaze material at the time of firing, irregular glaze is caused. The flow of the glaze is prevented and the variation of the glaze width is prevented, so that a uniform heating element formation surface is secured, and even a partial glaze with a narrow width of 0.5 mm or less can be stably formed, and low smoothness at low cost. It is an object of the present invention to provide a head capable of excellent printing on paper.

[0010]

According to the present invention, in a thermal head having a glaze layer formed on a substrate and a heating element formed on the glaze layer, a substrate material and a glaze are provided between the substrate and the glaze layer. The thermal head is provided with a reaction preventive layer for preventing a reaction with a material.

[0011]

According to the present invention, the reaction preventing layer prevents the reaction between the substrate material and the glaze material at the time of firing, and prevents expansion of the glaze width and nonuniformity of the glaze thickness.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in FIGS.

FIG. 1A shows a thermal head. A reaction preventive layer (barrier layer) 12 is formed on the upper surface of an alumina ceramic substrate 11 (Al ₂ O ₃ purity of 96 to 99.6%), and a glaze is formed on the upper surface of the reaction preventive layer 12. The layer 13 is formed, the heating element 14 is formed from the reaction preventing layer 12 to the glaze layer 13,
An electrode 15 is formed on the upper surface of the heating element 14, and a protective film 16 is further formed on the surface thereof.

The reaction preventive layer 12 formed between the substrate 11 and the glaze layer 13 is for preventing the reaction between the substrate material and the glaze material. For example, a vacuum deposition method or a sputtering method is used. , Coating-firing method, etc.
An O ₂ film is formed.

Since the reaction-preventing layer 12 is formed in this manner, the reaction between the substrate material and the glaze material during firing (about 1200 ° C.) is prevented, and the edge 13a of the glaze layer 13 is removed as shown in FIG. 1B. It is maintained linearly and clearly by the surface tension, and the phenomenon of flowing the glaze material from the printed edge unlike the conventional case does not occur.

Therefore, the expansion of the glaze width is prevented,
Since the ratio of the thickness to the width of the glaze layer 13 is high,
Printability on low-smoothness paper is improved. Furthermore, since the uneven expansion of the glaze width, which is considered to be affected by the nonuniformity of the substrate surface state, is eliminated, the unevenness on the heating element formation surface of the glaze layer 13 is also eliminated, and the thermal paper and the ink ribbon are evenly distributed. Maintaining contact, uniform heat generation is obtained.

FIG. 2 shows the relationship between the actually obtained glaze width and glaze thickness. When A is a 96% Al ₂ O ₃ substrate and the reaction preventive layer 12 of SiO ₂ film is present, B is 99.5%. % A
This is the case where the reaction preventing layer 12 of the SiO ₂ film is provided on the l ₂ O ₃ substrate. On the other hand, C is a 96% Al ₂ O ₃ substrate without a reaction preventive layer, and D is a 99.5% Al ₂ O ₃ substrate without a reaction preventive layer. That is, A and B are related to the present invention, and C and D are conventional.

[0018]

According to the present invention, since the reaction preventing layer for preventing the reaction between the substrate material and the glaze material is formed between the substrate and the glaze layer, when the substrate material and the glaze material are fired. The reaction preventing layer can effectively prevent the phenomenon in which the glaze material flows from the printed edge due to the reaction in 1. Therefore, the expansion of the glaze width can be prevented, a sufficient ratio of the thickness to the width of the glaze layer can be secured, and the printability on low-smoothness paper can be truly improved at low cost. Further, it is possible to prevent the generation of irregularities on the heating element forming surface of the glaze layer due to the uneven expansion of the glaze width, and in this respect, the printing quality can be improved.

[Brief description of drawings]

1A is a sectional view showing an embodiment of a thermal head of the present invention, and FIG. 1B is a plan view of a glaze layer in the thermal head.

FIG. 2 is a graph showing a relationship between a glaze width and a glaze thickness.

FIG. 3A is a cross-sectional view showing a conventional example of a thermal head, B
FIG. 7 is a sectional view showing another conventional example.

FIG. 4A is a cross-sectional view showing a conventional example of forming a glaze layer, and B.
Is a plan view of the glaze layer.

[Explanation of symbols]

 11 Substrate 12 Reaction prevention layer 13 Glaze layer 14 Heating element

Claims (1)

[Claims] 1. A thermal head having a glaze layer formed on a substrate and a heating element formed on the glaze layer, for preventing a reaction between the substrate material and the glaze material between the substrate and the glaze layer. A thermal head having a reaction preventive layer formed thereon.