JPH08174885A - Thermal print head - Google Patents

Abstract

PURPOSE: To provide a structure in which thermal energy at heating dots can be efficiently applied. CONSTITUTION: A thermal print head comprises a glazed layer 2 formed on an insulating board 1, a resistor layer 4 formed on the layer 2, a common conductor 6 and a plurality of individual conductors 5 so formed as to be opposed on the layer 2, and heating dots 7 formed on the layer 4 of the adjacent conductors 5 and 6, wherein a metal layer 3 is so formed between the board 1 and the layer 2 as to correspond to the dot 7. Further, the layer 3 between the board 1 and the layer 2 is formed of metal having higher melting point than that of a material for forming the layer 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermal print head,
Specifically, it relates to the structure of the glaze layer of the thermal print head.

[0002]

2. Description of the Related Art Generally, a thermal print head is roughly classified into two types, a thin film type and a thick film type, depending on the means by which a resistor layer is formed. The thin film type thermal print head is shown in FIG.
As shown in (a) and (b), which are perspective views and a sectional view thereof, a glaze layer 11 having a semicircular cross section is formed on the upper surface of the insulating substrate 10. Then, the resistor layer 12 is formed on the insulating substrate 10 and the glaze layer 11 by thin film forming means such as sputtering. This resistor layer 12
A conductive material is deposited on the upper surface of the individual conductor 13 and the common conductor 14
Are formed so as to face each other. When forming these individual and common conductors, a certain portion of the conductor material between the individual conductors 13 and the common conductors 14 is removed by etching to expose the lower resistor layer 12 and both electrodes 13 are formed. , 14 to generate heat from the resistor layer 12 between the electrodes 13 and 14 to form the heating dot 15. The protective layer (not shown) includes the glaze layer 11, the individual conductor 13, and the common conductor 1.
4. A thin film type thermal print head is formed by coating to protect the heating dots 15.

On the other hand, in the thick film type thermal print head, a glaze layer 11 is applied to the upper surface of the insulating substrate 10 as shown in the perspective view and the sectional view of the main part of FIGS. 4 (a) and 4 (b), respectively. It is formed by firing. The individual conductors 13 and the comb-shaped portions 14a of the common conductor are formed on the glaze layer 11 so as to be alternately adjacent to each other. A resistor layer 12 having a substantially arcuate cross section is formed by a thick film forming means so as to bridge the individual conductor 13 and the comb-toothed portion 14a of the common conductor.
The individual conductor 13 and the common conductor 14 are connected to the resistor layer 12, and the resistor layer is formed by applying a voltage between one individual conductor 13 and the comb-shaped portions 14a of two adjacent common conductors. Heat is generated in 12 and the heat generating dots 15 are formed. A protective layer (not shown) is formed to cover the glaze layer 11, the individual conductors 13, the common conductor 14, and the heating dots 15 to form a thick film type thermal print head.

[0004]

In recent years, electronic devices such as POS terminals and FAX, which use thermal print heads, have become smaller and more portable, and in particular, thermal print heads are required to save power. Therefore, in the conventional thermal print head described above, in order to efficiently transfer the heat energy generated in the heating dots to the print medium, a glaze layer having a low thermal conductivity is provided at a position corresponding to at least the heating dots on the insulating substrate. It is formed so that the heat generated by the heating dots does not escape to the insulating substrate side even if only a little.

Despite the presence of such a glaze layer, part of the thermal energy generated in the heating dots of the thermal print head passes through the glaze layer and escapes to the insulating substrate. Therefore, since it is necessary to generate more heat energy that escapes to the insulating substrate side than to generate heat from the heat-generating dots, the voltage required to drive the thermal print head becomes high, and portable batteries such as rechargeable batteries are portable. There is a problem that it is difficult to lower the power supply voltage level.

Further, since the heat energy generated in the heating dots passes through the glaze layer and escapes to the insulating substrate, the reproducibility of the dot shape of the printed heating dots is low, and the printing quality of the thermal printing head is improved. There was also a problem that I could not do it. It is an object of the present invention to provide a thermal print head having a structure capable of efficiently applying thermal energy at a heating dot.

[0007]

In order to solve the above-mentioned problems, the invention described in claim 1 of the present application provides a glaze layer formed on an insulating substrate and a resistor formed on the glaze layer. A body layer, a common conductor and a plurality of individual conductors formed so as to face each other on the glaze layer, and a heating dot defined in the resistor layer by the adjacent individual conductors and common conductors. The thermal print head is characterized in that a metal layer is formed between the insulating substrate and the glaze layer so as to correspond to the heating dots.

Further, the invention described in claim 2 of the present application is
The thermal print head according to claim 1, wherein the metal layer between the insulating substrate and the glaze layer is formed of a metal having a melting point higher than that of the material forming the glaze layer.

[0009]

In the thermal printing head, since the metal layer is formed between the insulating substrate and the glaze layer so as to correspond to the heating dot, the thermal energy for printing generated by the heating dot is radiated. Through the glaze layer. The thermal energy due to this radiation is efficiently reflected by the metal layer on the insulating substrate, and the radiated thermal energy returns to the heating dots again. As a result, the ratio of the thermal energy generated in the heating dots contributing to printing is increased, and the heating dots can be driven with a smaller applied voltage.

In the thermal print head, since the metal layer is formed so as to correspond to the heating dots, the heat energy generated in the heating dots passes through the glaze layer and is radiated corresponding to the heating dots. . As a result, the heat energy of the heating dots that have been diffused through the glaze layer is concentrated in the same shape as the heating dots, improving the dot reproducibility during printing and improving the printing quality of the thermal print head. Has the effect.

Further, in the thermal print head, since the metal layer between the insulating substrate and the glaze layer is made of a metal having a melting point higher than that of the material forming the glaze layer, the material forming the metal layer forms the glaze layer. Since the melting point is higher than that of the material to be formed, even if the glaze layer is formed by printing and baking after forming the metal layer, it does not affect the shape, characteristics, etc. of the metal layer. There is an effect that the manufacturing can be easily performed by adding one step of the known work content without largely changing the method.

[0012]

Embodiments of the thermal print head of the present invention will be described below with reference to the drawings. 1 (a) and 1 (b) are respectively a perspective view and a plan view of a main part of a thin film type thermal printing head according to an embodiment of the present invention, which is an elongated insulating substrate 1 made of alumina ceramic. The glaze layer 2 having a substantially arcuate cross section is formed by printing and firing an amorphous glass paste on the surface of the.

A plurality of rectangular metal layers 3 are formed on the insulating substrate 1 at regular intervals. The metal layer 3 is formed by depositing Cr by a thin film forming means by sputtering, and is formed by etching at a position and a size corresponding to a heating dot described later so as to correspond to a heating dot described later. Then, on the insulating substrate 1 and the glaze layer 2,
A plurality of resistor layers 4 made of ruthenium oxide are formed so as to extend in a strip shape in the longitudinal direction of the substrate. On these resistor layers 4, an individual conductor 5 and a common conductor 6 made of Al as a conductor material are formed so as to face each other. Between the individual conductors 5 and the common conductor 6, the conductor material is removed by etching with a constant width to expose the lower resistor layer 4, so that a voltage is applied between the conductors 5 and 6. As a result, heat is generated from the resistor layer 4 between the conductors 5 and 6, and the heating dot 7 is formed. Then, a protective layer (not shown) is formed so as to cover the exposed portions of the individual conductor 5, the common conductor 6 and the resistor layer 4, and the thermal print head is configured.

Although Cr is used for the metal layer formed by the thin film forming means in the above-mentioned embodiments, the same effect can be obtained by using Ni, Co, Ti or the like. Since the glaze layer is formed by printing and firing after the metal layer is formed, the melting point is higher than that of the glass paste that forms the glaze layer, and a thin film can be formed so that the metal layer does not melt due to firing of the glaze layer. As long as it is a metallic material, it is not particularly limited to Cr.

Further, in the above-mentioned embodiment, the metal layer formed by the thin film forming means is formed independently in accordance with the corresponding heating dots, but it may be formed integrally along the direction in which the heating dots are continuous. Good. Further, the size of the metal layer is formed to be approximately the same area as the heating dot, but by changing the area and thickness of the metal layer according to the specifications such as printing speed and accuracy required for the thermal print head. The thermal energy reflected by the metal layer can be adjusted, and not only a thermal print head with different specifications can be obtained with the same external dimensions and drive voltage as the conventional one, but also its production in comparison with the conventional thermal print head. It can also be manufactured at low cost without adding a large number of steps.

2 (a) and 2 (b) are respectively a perspective view and a plan view of an essential part of a thick film type thermal printing head according to another embodiment of the present invention, which is a long alumina ceramics sheet. A glaze layer 2 made of an amorphous glass paste is formed on the upper surface of the insulating substrate 1 by coating and firing. A metal layer 3 is formed between the insulating substrate 1 and the glaze layer 2 by a thick film forming means. This metal layer 3 is printed with gold paste at a position and a width corresponding to a resistor layer 4 described later.
It is fired to form a strip shape along the longitudinal direction of the insulating substrate 1 and a substantially rectangular cross section.

The conductor material made of gold paste is printed and fired to form the individual conductor 5 and the common conductor 6. Comb-shaped portions 6a are formed on the common conductor 6 so as to be alternately adjacent to the individual conductors 5. A resistor layer 4 made of ruthenium oxide is formed so as to bridge the comb-teeth portion 6a of the common conductor and the individual conductor 5. This resistor layer 4
The individual conductor 5 and the common conductor 6 are connected to each other, and heat is generated in the resistor layer 4 by applying a voltage between one individual conductor 5 and the comb-tooth-shaped portions 6a of two adjacent common conductors. The heating dots 7 will be formed. Then, a protective layer (not shown) is formed so as to cover the resistor layer 4, the individual conductors 5 and the common conductor 6 to configure the thermal printing head.

Although gold is used for the metal layer formed by the thick film forming means in the above-mentioned embodiments, the same effect can be obtained by using silver, copper or the like. Since the glaze layer is formed by coating and firing after the metal layer is formed, the melting point is higher than that of the glass paste forming the glaze layer and the thick film can be formed so that the metal layer does not melt due to firing of the glaze layer. The metal material is not particularly limited to gold.

Further, in the above-mentioned embodiment, the metal layer formed by the thick film forming means is integrally formed along the longitudinal direction of the insulating substrate. Similarly, they may be formed independently so as to correspond to the size of each heat generation dot. Furthermore, although an amorphous glass paste is used for the glaze layer, a heat resistant resin may be used, and when the heat resistant resin is used, the temperature at which the glaze layer is formed is lower than that when glass is used. Therefore, the melting point required for the metal material used for the metal layer is lowered, the conditions for the metal material used for the metal layer are reduced, and various materials can be used.

In the present invention, the thin film type thermal printing head is combined with the metal layer formed by the thin film forming means, and the thick film type thermal printing head is combined with the metal layer formed by the thick film forming means. Any metal material that does not melt may be used, such as a metal layer formed by a thick film forming means on a thin-film thermal print head,
The same effect can be obtained by combining a thick film type thermal print head with a metal layer formed by a thin film forming means.

The present invention is not particularly limited to the formation method, the shape, the material and the like described in the above embodiments.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a thermal print head of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the thermal print head of the present invention.

FIG. 3 is an explanatory diagram showing a conventional thermal print head.

FIG. 4 is an explanatory diagram showing a conventional thermal print head.

[Explanation of symbols]

 1 ... Insulating substrate 2 ... Glaze layer 3 ... Metal layer 4 ... Resistor layer 5 ... Individual conductor 6 ... Common conductor 7 ... Heating dot 10 ... Insulating substrate 11 ... Glaze layer 12 ... Resistor layer 13 ... Individual conductor 14 ... Common conductor 15 ... Heating dot

Claims (2)

[Claims] 1. A glaze layer formed on an insulating substrate,
The resistor layer formed on the glaze layer, the common conductor and the plurality of individual conductors formed so as to face each other on the glaze layer, and the adjacent individual conductor and the common conductor form an image on the resistor layer. A thermal print head having a heating dot formed, wherein a metal layer is formed between the insulating substrate and the glaze layer so as to correspond to the heating dot. . 2. The thermal print head according to claim 1, wherein the metal layer between the insulating substrate and the glaze layer is formed of a metal having a melting point higher than that of a material forming the glaze layer.