JPS61139453A - Thermal head - Google Patents

Abstract

PURPOSE:To achieve the improvement of printing quality, by a method wherein the second glaze layer is formed on the first glaze layer of the part other than the electrode conductive part of a ceramic substrate and its thickness is made to be of almost the same film thickness as the thickness of electrode conductor to form a flat heating resistor. CONSTITUTION:The first glaze layer 2 is printed on all the surface of a ceramic substrate 1 and baked. Then, the second glaze layer 6 is printed on almost all the surface other than the pat in which an electrode conductor 3 is formed and baked. Further, the combed electrode conductor 3 is printed on the glaze layer the dent of which is formed and baked. Then, a heating resistor 4 is, in a one line state, printed on the electrode conductor 3 and baked. Almost all the surfaces of electrode conductor 3, the second glaze layer 6 and heating resistor 4 are, lastly, covered with a protection layer 5. In that case, the first and the second glaze layers shall be of the same material and be achieved to be united by maximizing the joining property between the layers. Further, the film thicknesses of electrode conductor 3 and the second glaze layer 6 are made to be of almost the same thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thermal head, and particularly to a thermal head suitable for a recording section of a printer.

[Background of the invention]

A conventional thermal head will be explained with reference to FIGS. 3 and 4.

A ceramic substrate 1 is made of an insulating material such as alumina. Reference numeral 2 denotes a glaze layer, which is made of an insulating material such as glass, and serves to store heat in the heating element. Reference numeral 5 denotes an electrode conductor made of gold or the like, which is formed on the glaze layer 2 in a comb-shaped pair.

Further, reference numeral 4 denotes a heating element resistor made of an oxide such as ruthenium oxide, which is formed in the shape of a single line on the opposing electrode conductors 3. The heating resistor 4 is covered with a protective layer made of an insulator such as 5Fi glass.

In the thermal head with the above structure, the electrode conductor protrudes in a convex shape, and the heating resistor generates a depression between the electrode conductors, resulting in poor paper contact at the necessary heating part of the heating resistor.
Printing may become difficult. Further, when the film thickness is increased to reduce the conductor resistance of the electrode conductor, the depression becomes even more noticeable.

Therefore, as a method of forming a heating resistor in a planar manner to improve paper contact, there is, for example, Japanese Patent Application Laid-Open No. 56-113479. That is, an electrode conductor is buried in a groove provided in the substrate,
A heating resistor is provided thereon. However, with this method, it is necessary to precisely process the grooves on the substrate.
In particular, commonly used ceramic substrates have the problem of being difficult to process.

[Purpose of the invention]

An object of the present invention is to provide a thermal head that has a flat heating resistor and has good paper contact and print quality.

[Summary of the invention]

That is, the above objective is achieved by forming the next glaze layer on the glaze layer in the portion of the ceramic substrate excluding the electrode conductor portion, and forming a flat heating resistor by making the layer almost as thick as the electrode conductor. (It is.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

A first glaze layer is printed and fired on the entire surface of the ceramic substrate 1, and then the electrode conductor 3 is printed and fired.
The second glaze layer 6 is printed and fired on almost the entire surface other than the area where the glaze is formed. A comb-shaped electrode conductor 6 is printed and fired on the glaze layer with depressions, and a heating resistor 4 is printed in a line shape on the electrode conductor 3 and fired. Finally, a protective layer 5 is applied to the electrode conductor 3. Second glaze layer and heating resistor 6
almost completely covered. In the above thermal head, the first glaze layer 2 and the second glaze layer 6 are made of the same material, and the bonding between the layers is maximized to integrate the glaze layers. The film thickness is almost the same.

Therefore, as in the conventional case, the heating resistor becomes convex at the electrode conductor part and forms a depression between the electrode conductors, thereby
The heating resistor on the upper part of the electrode conductor alone does not hit the paper, and a flat heating resistor with few irregularities can be formed. Therefore, the contact area of the heat generating resistor to the paper increases, so that the print quality is improved. In this embodiment, a case has been described in which the first and second glaze layers are formed in two steps, but the same effect can be obtained when the first and second glaze layers are formed simultaneously.

Furthermore, the second glaze layer does not need to be formed on the entire surface of the first glaze layer except for the part where the electrode conductor 3 is formed.
It is sufficient if it is formed under the heating resistor. According to this, the contact area between the thermal head and the paper becomes smaller compared to the case where the second glaze layer is formed on the entire surface. In turn, the heating resistor of the thermal head makes good contact with the paper, making it possible to print with high quality.

〔Effect of the invention〕

According to the present invention, a flat @thermal resistor can be formed in the thermal head, and a flat protective layer can be formed accordingly, so that the printing property on the glaze layer of the heating resistor is good, and A thermal head with good thermal contact between the heating element and paper and good printing quality can be obtained.

[Brief explanation of drawings]

FIG. 1 is a front view showing a thermal head structure according to the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 6 is a front view showing a conventional thermal head structure, and FIG. A- in the diagram
A@ cross-sectional view, 1...ceramic substrate, 2...
First glaze layer, 3... Electrode conductor, 4... Heat generating resistor, 5... Protective layer, 6... Second glaze layer. $sr5 $112] $4 Figure $z (21

Claims (1)

[Scope of Claims] 1. A thermal head characterized in that a second glaze layer is provided between electrode conductor forming portions provided on a first glaze layer of an insulating substrate. 2. The thermal head according to claim 1, wherein the second glaze layer is formed below the heating resistor. 3. The thermal head according to claim 1 or 2, wherein the second glaze layer has approximately the same thickness as the electrode conductor forming portion.