JP2546120Y2 - Thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a thermal head used for a thermal printer, for example.

(B) Prior art FIG. 4 is a cross-sectional view of a conventional (partial glaze type) thin-film thermal head, and FIG. 5 is a cross-sectional view showing a conventional (full-glaze type) thin-film thermal head. It is.

The conventional thin-film thermal head shown in FIG. 4 is formed by printing a belt-like glaze layer 82 having a semicircular cross section on the upper surface of an insulating substrate, for example, an alumina ceramic substrate 81, and forming tantalum nitride or the like on the upper surface of the glaze layer 82. The heating resistance film 83 is formed, and lead electrodes (common electrode and individual electrode) 84 are formed on both sides of the bottom of the heating resistance film 83 so as to face each other. The surface of the substrate 81, the resistance film 83, and the lead electrode 84 is covered with a protective layer 85 such as a silicon dioxide film.
The conventional thin-film thermal head shown in FIG. 5 has a thin-film glaze layer 82a formed on the upper surface of an insulating substrate 81a by printing.
A heating resistance film 83a is formed on the upper surface of the thin film glaze layer 82a, and a lead electrode 84a in which a common electrode and an individual electrode are arranged at a constant interval on the upper surface of the heating resistance film 83a, that is, a lead electrode 84a. The protective layer 85a is formed on the surface of the substrate 81a, the resistance film 83a, and the lead electrode 84a.

The thermal head applies a pulse voltage between the lead electrodes 84 (84a), and generates a heating portion A of the heating resistance film 83 (83a).
By selectively causing (A ′) to generate heat, this heat generating portion A
Information is printed on the recording paper that is pressure-fed and fed in a superposed state with the thermal paper (thermal ribbon) for (A ′).

(C) Problems to be Solved by the Invention In the above-mentioned conventional thermal head (the thermal head shown in FIGS. 4 and 5), the angle with respect to the recording paper is not appropriate for printing when the head is tilted for printing. For example, the fifth
In the thin-film thermal head shown in the figure, the heat generating portion and the protective layer surface on the heat generating portion are parallel to the surface of the insulating substrate. In the thin-film thermal head shown in FIG. 4, the tangent line of the protective layer on the heat generating portion is parallel to the insulating substrate. For this reason, there is a problem in the pressure contact state between the heat generating portion (the protective layer on the heat generating portion) and the recording paper, and there is a possibility that appropriate printing accuracy cannot be secured depending on the size or thickness of the recording paper. In addition, the thin-film thermal head shown in FIG. 4 has disadvantages such as severe wear of the protective layer.

Therefore, in recent years, a thermal head shown in FIGS. 6 and 7 has been proposed. FIG. 6 is an explanatory view of a partial glaze type thermal head, and FIG. 7 is an explanatory view of a full glaze type thermal head.

The partial glaze type thermal head shown in FIG.
Is displaced from the center of the cross-sectionally curved glaze layer, that is, disposed on an inclined surface, and the thin-film thermal head of FIG. 7 cuts an end of the insulating substrate 81a to form an inclined surface (inclined surface) 81b, The heat generating portion A 'is provided on the inclined surface 81b. Each of these thermal heads is set so that the heat generating portion is not horizontal to the insulating substrate surface but has a certain angle. That is, by setting the heat generating portion and the recording paper so as to face each other (contact surface) at a certain angle, the adhesion between the heat generating portion and the recording paper is ensured.

However, in the case of the partial glaze type thermal head shown in FIG. 6 and the full glaze type thermal head shown in FIG. 7, the heating portion is positioned at a desired position with respect to the inclined surface (in the photolithography or printing step), that is, with high positional accuracy. Forming is not unacceptable in terms of manufacturing work, and if the position of the heat generating portion is slightly deviated, there is a disadvantage that the printing quality is greatly reduced. Further, in the entire glaze type thermal head, the end portion of the insulating substrate must be cut and formed on the inclined surface, and there is a disadvantage that the substrate cost is increased.

An object of the present invention is to solve the above-mentioned problems, and to provide a thermal head which can be easily formed and has high print quality.

(D) Means and action for solving the problem In order to achieve this object, the thermal head of the present invention has the following configuration.

The thermal head is provided with a glaze layer on an upper surface of an insulating substrate, a heating resistor film formed on the surface of the glaze layer, and a lead electrode formed on the heating resistor film. In a thermal head provided with a protective layer for covering an electrode, a flat inclined surface portion is formed on the protective layer so that a portion where the thickness of the protective layer is reduced is provided corresponding to a heat generating portion of a heat generating resistance film. The thickness of the thin portion is gradually increased from at least one side of the heat generating portion to the other side.

In the thermal head having such a configuration, the position of the protective layer corresponding to the heat generating portion, that is, the press-contact surface of the protective layer that presses against the recording paper and prints information is formed as a flat inclined surface. The flat inclined surface is formed by, for example, polishing the protective layer after the thermal head is formed by a conventional process. Therefore, until the thermal head is completed, since it is completely the same as the conventional one, there is a problem in manufacturing, that is, it is difficult to secure the positional accuracy for forming the heating portion on the inclined surface,
In addition, disadvantages such as an increase in the cost of the substrate caused by cutting and forming the end of the insulating substrate are eliminated. Further, by forming the protective layer corresponding to the heat generating portion on the flat inclined surface, it is not possible to realize easy formation, and the protective layer corresponding to the heat generating portion has a certain angle with respect to the insulating substrate. As a result, an appropriate press-contact state between the recording paper and the heat generating portion (protective layer) can be obtained, and high printing accuracy can always be ensured.

(E) Embodiment FIGS. 1 and 2 show a specific embodiment of the thermal head according to the present invention. FIG. 1 shows an example in which the present invention is applied to a partial glaze type thermal head. FIG. 2 shows an example in which the present invention is applied to an entire glaze type thermal head.

The partial glaze type thermal head shown in FIG. 1 has an insulating substrate,
For example, a belt-like glaze layer 2 having a semicircular cross section is formed by printing on the upper surface of an alumina ceramic substrate 1, and a heating resistance film 3 such as tantalum nitride is formed on the upper surface of the glaze layer 2.
Further, lead electrodes (common electrode and individual electrode) 4 are formed on both sides of the bottom of the heating resistor film 3 so as to face each other. And
A protective layer 5 such as a silicon dioxide film is deposited on the surfaces of the substrate 1, the resistive film 2, and the lead electrode 4.

The thin-film thermal head shown in FIG. 2 has a thin-film glaze layer 2a printed on the upper surface of an insulating substrate 1a, a heating resistor film 3a formed on the upper surface of the thin-film glaze layer 2a, and a heating resistor film 3a. Forming a lead electrode 4a in which a common electrode and an individual electrode are arranged in opposition at regular intervals on the upper surface of 3a, and a protective layer 5a is deposited on the surface of the substrate 1a, the resistive film 2a and the lead electrode 4a. Has formed.

The feature of this invention is that the heating part A of the protective layer 5 (5a) is used.
(A ') The point is that a flat inclined surface portion 6 (6a) is formed at the corresponding position.

The flat inclined surface portion 6 (6a) is polished, for example, so that the position corresponding to the heat generating portion A (A ') of the protective layer 5 (5a) formed as before is inclined at a fixed angle with respect to the insulating substrate 1 (1a). Formed. As the polishing angle, an angle with the best pressing state against the recording paper (not shown), that is, an angle with high printing accuracy is selected. Thereby, in the full-surface glaze type thermal head, a method in which a heating section A 'is provided on the conventionally proposed head shown in FIG. 7, that is, an end inclined surface of the insulating substrate 1a,
In the partial glaze type thermal head, print quality similar to that of the conventionally proposed head shown in FIG. 6, that is, the method in which the heat generating portion A is provided on a curved inclined surface can be obtained.

However, in the case of the embodiment, the thickness of the protective film 5 (5a) on the heat generating portion A (A ') differs between the edge side and the opposite edge side of the insulating substrate 1 (1a) due to the flat inclined surface portion 6 (6a). It is considered that a difference in the amount of heat conduction occurs. But the third
As shown in the figure, for example, the difference in the amount of heat conduction can be easily solved by selectively using the Myan type heating element 7 and giving a gradient to the temperature distribution of the heating element 3 (3a).

In the embodiment, the heat generating portion A (A ') is connected to the insulating substrate 1 (1a).
An example of a so-called real edge head, which is located at the end of the head, is shown, but the present invention can be applied to a head other than the real edge type. In this case, by forming the flat inclined surface portion 6 larger than the width of the heat generating portion A, good printing accuracy can be ensured even when the position of the heat generating portion A is slightly shifted during manufacturing. In the embodiment of FIG. 1 described above, the flat inclined surface portion 6 is formed on the protective layer 5 of the partial glaze type thermal head in which the heat generating portion A is provided at the apex position of the cross-sectional curved glaze 2. In the thermal head,
Although the heat generating portion A is provided at a position shifted from the vertex position of the curved glaze 2, the flat inclined surface portion 6 may be formed on the protective layer 5. In this case, the inclination angle θ of the flat inclined surface portion 6 (first
(See the figure) can be further increased.

In the thermal head having such a configuration, the insulating substrate 1 (1a), the glaze layer 2 (2a), the heating resistor film 3 (3
a), the lead electrode 4 (4a) and the protective film 5 (5a) are formed by exactly the same manufacturing process as before, and then the protective film 5 (5a) is formed.
In the simple glazing-type thermal head, the heat generating portion A is located at the center of the glaze layer 2 with a simple cross-section by simply polishing the position corresponding to the heat generating portion A (A ') to the flat inclined surface portion 6 (6a). The same operation and effect as those formed on the inclined surface with further displacement can be exhibited. That is, the flat inclined surface portion (heating portion A) 6 is pressed against the recording paper in an appropriate state, and the printing accuracy is improved. In addition, in the full-surface glaze type thermal head, the same operation and effect as in the case where the end of the insulating substrate 1a is cut into an inclined surface and the heat generating portion A 'is formed on the inclined surface are exhibited. Therefore, disadvantages in the manufacturing operation, that is, in the case of the partial glaze type thermal head, it is difficult to secure the positional accuracy when forming the heat generating portion, and in the case of the full glaze type thermal head, the cost increase due to the cutting of the insulating substrate is eliminated. Thus, a thermal head with high printing accuracy can be obtained.

(F) Effects of the invention In the invention, as described above, a portion where the thickness of the protective layer is reduced by forming the flat inclined surface portion on the protective layer is provided corresponding to the heat generating portion of the heat generating resistance film. Since the thinner part of the layer is made thicker at least from one side of the heat generating portion to the other side, after the thermal head is formed by the conventional manufacturing method, the position of the protective layer corresponding to the heat generating portion is simply changed. With a simple operation of simply polishing the recording paper, it is possible to obtain a thermal head with good press contact with the recording paper and high printing accuracy.

In addition, since the thermal head itself is formed in exactly the same manufacturing process as before, it is difficult to secure positional accuracy due to the formation of misalignment of the heat generating portion, and the substrate cost increase due to the cutting of the insulating substrate end is eliminated. It has an excellent effect of achieving the purpose of the invention.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing an example partial glaze type thermal head, FIG. 2 is a cross-sectional view of a main part showing a thin film type thermal head of the embodiment, and FIG. FIG. 4 is an enlarged cross-sectional view of a main part showing a conventional thin-film thermal head, FIG. 5 is an enlarged cross-sectional view of a main part showing a conventional thin-film thermal head, and FIG. FIG. 7 is an explanatory view showing a thin-film thermal head in which a heating portion is displaced from the center of the glaze layer. FIG. 7 shows a thin-film thermal head in which an end of an insulating substrate is cut into an inclined surface and a heating portion is provided on the inclined surface. FIG. 1.1a: insulating substrate, 2.2a: glaze layer, 3.3a: heating resistance film, 4.4a: lead electrode, 5.5a: protective layer, 6.6a:
Flat inclined surface portion, A · A ′: heating portion.

Claims (1)

(57) [Scope of request for utility model registration] 1. A glaze layer is provided on an upper surface of an insulating substrate, a heating resistor film is formed on the surface of the glaze layer, and a lead electrode is formed on the heating resistor film. In a thermal head provided with a protective layer covering the electrodes for use, a portion where the thickness of the protective layer is reduced by forming a flat inclined surface portion on the protective layer is provided corresponding to the heat generating portion of the heat generating resistance film. The thermal head according to claim 1, wherein a portion having a smaller layer thickness sequentially increases in thickness from at least one side of the heat generating portion toward the other side.