JPH08224901A - Thermal head - Google Patents

Abstract

PURPOSE: To enhance abrasion resistance and humidity resistance by forming a common electrode so as to extend the same up to the end part of a substrate to bond the protective film of a head end part so as not to peel the same. CONSTITUTION: A glaze layer 2 is formed to an insulating substrate 1 composed of alumina ceramics or the like in the vicinity of the end part 1A thereof and resistor layers 3, 4 are formed on the substrate 1 and the glaze layer 2 and metal layers 5, 6, 7 are formed thereon and, further, the entire surfaces of those layers are covered with a protective film. Since the surface of the metal layer 7 is porous, the adhesiveness with the protective film 8 is high and the adhesiveness between the metal layer 7, the resistor film 4 and the glaze layer 2 is also high. By forming the resistor layers and a common electrode up to the end part 1A of a head, the resistor layers and common electrode in the vicinity of the end part 1A can be also used as bonding layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thermal head used in a thermal recording device.

[0002]

2. Description of the Related Art In a thermal recording apparatus which conducts recording by energizing a resistor formed in a thermal head to generate Joule heat and transmitting this heat to a thermal transfer ribbon, the ink of the thermal transfer ribbon is printed on the surface of the paper. To ensure reliable transfer, a dedicated paper with a smooth surface is generally used. However, when recording is performed on a normal paper whose surface is not so smooth, a thermal transfer ribbon having a three-layer structure in which a resin-based ink is applied to a base such as a polyester film with a release layer interposed is used. When a thermal transfer ribbon using such a resin-based ink is used, it is necessary to peel off the resin ink at a large angle within a short time after the transfer to the paper so that the resin inks are not fused again. Therefore, as a thermal head suitable for this type of thermal transfer ribbon, a thermal head having a heating portion formed at the end has been conventionally used.

5 and 6 are views showing the structure of the above-mentioned conventional thermal head. FIG. 5 shows a plane of a surface in contact with the thermal transfer ribbon, and FIG. 6 shows a cross section near the end. In the figure, reference numeral 1 denotes an insulating substrate, and a kamaboko-shaped glaze layer 2 is formed on an end portion of the substrate 1 as shown in FIG.
The resistor layer 3, the lead electrode 5, the common electrode 6 and the protective film 8 are formed on the glaze layer 2. As shown in FIG. 5, the common electrode 6 is made common and a signal is selectively applied to each lead electrode to generate heat in the resistor layer 3 between the lead electrode and the common electrode, and this heat is transferred to the thermal transfer ribbon. . By thus forming the heat generating portion near the end of the thermal head, the thermal transfer ribbon is peeled off from the paper at a large angle immediately after the resin ink is transferred to the paper.

[0004]

Generally, in the above-mentioned conventional thermal head, when the heat generating portion is made to approach the end portion of the head, the adhesion between the glaze layer 2 and the protective film 8 is poor, so that the glaze layer is The protective film 8 may be peeled off from 2. This is because the adhesion between the glaze layer 2 and the protective film 8 is poor as described above, so it is conceivable that a structure in which the protective film and the 8 glaze layer 2 do not adhere to each other at the end portion may be used. When ceramics is used, it is difficult to directly form the heat generating portion, and since the glaze layer has to be formed under the heat generating portion, the above-described configuration cannot be adopted.

Particularly, when the protective film 8 is formed of a nitride film material having a high hardness for the purpose of prolonging the service life by sputtering, since it has a high hardness, a crack is generated from the end of the thermal head during use. There is a greater risk that the protective film will enter and the protective film will gradually come off. Then, such a problem may cause a decrease in moisture resistance and corrosion of the common electrode due to moisture, leading to poor conduction.

An object of the present invention is to provide a thermal head which can be bonded so that the protective film at the head end portion does not come off, and which can improve wear resistance and moisture resistance.

[0007]

In view of the above-mentioned conventional problems, the present invention employs the following configuration. That is,
A glaze layer is provided at an end of the substrate, a resistor layer is provided on the glaze layer, and a common electrode is provided between the end of the substrate and the resistor layer. In addition, in the thermal head in which the surface of the substrate including the common electrode is covered with a protective film, the common electrode is formed so as to extend until it contacts the end portion of the substrate.

[0008]

In the thermal head of the present invention, the common electrode for energizing the resistor layer serving as the heat generating portion is extended until it comes into contact with the end portion of the substrate, so that the common electrode prevents peeling of the protective film or the like. Work to prevent.

[0009]

1 is a plan view showing the structure of a thermal head according to the present invention, and FIG. 2 is a partial cross-sectional view near the end 1A thereof. In the figure, reference numeral 1 represents an insulating substrate such as alumina ceramics, and a glaze layer 2 is formed in the vicinity of an end 1A of the substrate 1. Substrate 1 and glaze layer 2
Is formed with resistor layers 3 and 4, metal layers 5, 6 and 7 are formed on the resistor layers 3 and 4, and the surface thereof is covered with a protective film 8. The difference from the thermal head shown in FIGS. 5 and 6 as a conventional example is that the end portion 1A of the head is different.
That is, the dummy resistor layer 4 and the metal layer 7 are formed as a bonding layer on the.

This thermal head is manufactured by the following steps. First, after the glaze 2 is screen-printed on the substrate 1 and baked, a resistor layer and a metal film such as Al are formed on the entire surface by sputtering, and a resist process and an etching process are performed twice to form the resistor layer and the Al layer. Pattern. Thereafter, a nitride film is sputtered on the entire surface, and when a heat generating portion is formed on the extreme portion 1A of the head, the head end portion 1A is ground by a grinder or the like.

As described above, the thermal head having the resistive layer 4 and the AL metal layer 7 interposed between the glaze layer and the protective film at the end 1A of the substrate is constructed. Since the surface of the metal film 7 is porous, it has high adhesiveness to the protective film 8, and also has high adhesiveness between the metal layer 7, the resistor layer 4 and the glaze layer 2. Therefore, the protective film 8 is not peeled off from the head end portion 1A, and a thermal head having excellent wear resistance and moisture resistance is formed. In the above embodiment, the bonding layer is formed only on the head end portion 1A on the side where the thermal transfer ribbon is peeled off from the paper, but, for example, as shown in FIG. 3, it is also bonded to the other end portion 1A such as the top end of the head. It is possible to increase the bonding strength of the entire protective film by forming the layer.

In each of the above examples, the resistor layer for forming the heat generating portion, the lead electrode and the common electrode are separately formed with a bonding layer. For example, as shown in FIG. By forming the common electrode up to the head end portion 1A, the resistor layer near the end portion 1A and the common electrode can also serve as the bonding layer in the present invention. In each of the examples, the glaze layer was formed only in the vicinity of the end portion 1A of the ceramics substrate. However, for example, it is applied to a thermal head using a substrate obtained by firing the glaze layer on the entire surface of a metal substrate. be able to. Further, the present invention can be applied to a thermal head in which no glaze layer is formed on the surface, and is particularly effective when a substrate having a smooth surface is used.

[0013]

As described above, according to the present invention, it is possible to prevent the protective film from peeling off at the end portion of the substrate by the common electrode, and to provide the thermal head excellent in abrasion resistance and moisture resistance and excellent in reliability. Can be configured. Further, there is an advantage that the common electrode can be used together with the bonding layer.

[Brief description of drawings]

FIG. 1 is a plan view of a thermal head according to the present invention.

FIG. 2 is a partial sectional view of the thermal head.

FIG. 3 is a plan view of another thermal head according to the present invention.

FIG. 4 is a plan view of another thermal head according to the present invention.

FIG. 5 is a plan view showing the structure of a conventional thermal head.

FIG. 6 is a partial sectional view of a conventional thermal head.

[Explanation of symbols]

 1-Substrate 2-Glaze Layer 3-Resistor Layer (Heating Part) 4-Resistor Layer (Joining Layer) 5-Lead Electrode 6-Common Electrode 7-Metal Layer (Joining Layer) 8-Protective Film

Claims (1)

[Claims] 1. A glaze layer is provided on an end of a substrate, a resistor layer is provided on the glaze layer, and a common electrode is provided between the end of the substrate and the resistor layer. In a thermal head having a body layer, a glaze layer, and a surface of the substrate including a common electrode covered with a protective film, the common electrode is formed to extend until it contacts an end of the substrate. Thermal head.