JPH0899422A - End face type thermal head substrate - Google Patents

Abstract

(57) [Abstract] [Purpose] A bulge is not formed near the ridge where the main surface and the end face intersect, the flatness of the glaze layer surface is further increased, and the printing efficiency is high, and uneven density and lines during printing are achieved. Does not cause snoring.
Further, when the wiring such as the electrodes is formed, the number of disconnection is small, and the yield of the thermal head is high. A ceramic substrate 15 having a pair of main surfaces 11 and 12 facing each other and an end surface 13 adjacent to these main surfaces and forming a convex curved surface, and a glaze layer 14 formed on the end surface 13.
An end surface type thermal head substrate provided with
3, a straight groove 16 is formed along the length direction of the ceramic substrate 15, and the glaze layer 14 having a convex curved surface is embedded in the straight groove 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate used for a thermal head of a thermal transfer printer. More specifically, the present invention relates to an end face type thermal head substrate having a glaze layer formed on the end face of a ceramic substrate and capable of printing or printing on hard paper or rough paper satisfactorily and at high speed.

[0002]

2. Description of the Related Art In a thermal head using this type of substrate, since the surface on which the heating resistor is formed is located at the end face of the substrate, it is easy to flatten the heating resistor portion. It has the advantages that it can be brought into uniform contact with the ink film and the ink film, and that it does not hinder the platen roller and the like. As a result, this type of thermal head can increase the printing pressure for printing and also has the effect of heat storage and heat dissipation of the glaze layer, so that it can print or print well even on rough paper such as plain paper or hard paper such as cards. You can
In addition, the device can be made smaller and lighter.

Conventionally, as shown in FIG. 4, a ceramic substrate 5 is used.
An end surface type thermal head substrate in which a curved glaze layer 4 is formed on a flat end surface 3 in the longitudinal direction is proposed (Japanese Patent Laid-Open No. 60-21263). The glaze layer 4 is obtained by applying a glass paste with a uniform thickness to the flat end face 3 of the ceramic substrate 5 and firing the paste at a high temperature, and the glass melted during firing becomes a medium-high shape due to its surface tension and is gently convex. Form a curved surface. In other words, the thickness of the glaze layer 4 on the end face 3 becomes smaller as it approaches the principal faces 1 and 2, and the glaze layer is extremely thin at the edge portion of the substrate where the end face 3 and the principal face 1 or 2 intersect. It has a thick structure in the center. In this thermal head, a larger number of resistors are alternately formed in a comb tooth array in the length direction on the surface of the glaze layer.

[0004]

However, the above end face type thermal head substrate has the following drawbacks. Since the size of the end face in the thickness direction of the substrate, that is, the width of the end face, is narrow in the glaze layer formed on the end face, due to the wettability of the glass and the surface tension of the glass with respect to the ceramic substrate, the glass melted during the glaze firing is the main component. There is a tendency that a part of the molten glass flows on the surface, or the molten glass that has flowed forms a bulge near the ridge of the substrate where the end surface and the main surface intersect. When the glass partially flows to the main surface side as described above, the thickness of the glaze layer becomes smaller than that in the portion where the glass did not flow, and the flow rate is not constant, so that the thickness of the glaze layer varies. Further, these are also a cause of undulation near the top of the glaze layer. as a result,
The heat generated from the resistor cannot be uniformly stored in the glaze layer, and the heat radiation during printing is also non-uniform, resulting in defects such as uneven density and lines. Since the ridge line portion of the substrate where the end surface and the main surface intersect is angled, disconnection may occur when wiring such as electrodes is formed by a thin film process or the like, and the yield as a thermal head decreases.

An object of the present invention is to form a swollen portion in the vicinity of a ridge, to improve the flatness of the surface of the glaze layer, to improve printing efficiency, and to prevent uneven density and line spread during printing. The purpose is to provide a substrate for a thermal head. Another object of the present invention is to provide an end face type thermal head substrate which has few breakages when wiring electrodes and the like and has a high yield of the thermal head.

[0006]

In order to achieve the above object, the structure of the present invention will be described with reference to FIGS.
In the end surface type thermal head substrate of the present invention, a straight groove 16 is provided along the length direction on the end surface 13 forming a convex curved surface in the length direction of the ceramic substrate 15, and the layer surface is convex on the straight groove 16. The glaze layer 14 having a curved surface is embedded.

The bottom surface 16a of the straight groove 16 may be flat, curved, or V-shaped. However, the bottom surface 16a
Is preferably flat and orthogonal to the main surfaces 11 and 12. This is preferable because the glaze layer 14 embedded in the straight groove 16 has uniform heat storage and heat dissipation functions in the thickness direction of the substrate 15. Also, as shown in FIGS. 1 and 3,
The glaze layer 14 may be embedded in the straight groove 16 so that the layer surface has the same radius of curvature as the convex curved surface of the end face 13.
As shown in FIG. 2, the layer surface of the glaze layer 14 ′ is the end surface 13
It is also possible to embed the glaze layer 14 ′ in the straight groove 16 so that the glaze layer 14 ′ protrudes by s from the virtual convex surface. By embedding the glaze layer 14 'in this way, it becomes possible to increase the pressing force on the platen roller when the thermal head is used. When the center of the heating resistor is formed at the center of the end face in the thickness direction of the ceramic substrate, the groove center in the width direction is made to coincide with the center of the end face 13 in the thickness direction of the ceramic substrate 15, that is, the end face 13 Straight groove 16 on top of
It is preferable to provide since the heat storage and heat radiating action of the glaze layer can be made more constant even if the formation position of the heating resistor varies. When the glaze layer 14 is buried, it is necessary that the molten glass to be the glaze layer does not flow from the upper end of the straight groove 16 toward the end face 13.

The width h of the straight groove 16 of the present invention changes according to the thickness t of the ceramic substrate 15, and the ratio h / t is preferably about 0.1 to 0.9. For example, the thickness t is 1 to 2.5
In the range of mm, the width h is preferably about 0.1 to 2.25 mm. If it is less than 0.1 mm, the heat storage and heat dissipation effect of the glaze layer 14 is poor, and if it exceeds 2.25 mm, the straight groove 16 is formed.
The upper end 17 of the is easily damaged. The depth d of the straight groove 16 from the upper end 17 is 5 to 5 depending on the heat capacity of the heating resistor.
It is determined in the range of 300 μm. Further, the protrusion amount s on the layer surface of the glaze layer is preferably 5 to 20 μm.

The straight groove on the end face is accurately formed in a straight line literally in the length direction of the substrate by mechanical processing such as grinding. To embed the glaze layer in the direct groove, fill the direct groove by a means such as printing, spraying or drawing a glass paste in which glass powder, organic binder, solvent, etc. are kneaded, and fire at a temperature above the softening point of the glass. Done by.

[0010]

Since the straight groove is provided on the end surface forming the convex curved surface of the ceramic substrate and the glaze layer is embedded in the straight groove, the molten glass remains in the straight groove during the glaze firing, and Not affected by wettability and surface tension. As a result, the thickness distribution of the glaze layer in the substrate length direction becomes uniform and waviness is reduced. Further, if the bottom surface of the straight groove is flat, the thickness of the glaze layer in the width direction of the substrate has less variation. As a result, the heat storage and heat dissipation functions of the glaze layer are made uniform, and the printing on the heat-sensitive paper and the transfer paper on the platen roller is made uniform, so that unevenness in light and shade, line drawing and the like are eliminated. Also, the glaze layer surface protrudes from the end face,
Since the layer surface of the glaze layer has a convex curved surface, the pressure on the platen roller is increased, and clear printing or printing can be performed on rough plain paper or hard paper. Further, when a thermal head is manufactured using this substrate, since the curved surface is continuously inclined from the end surface to the main surface, disconnection of wiring due to a thin film process or the like is unlikely to occur.

[0011]

The present invention will be described in detail below with reference to examples. The present invention is not limited by this embodiment. A ceramic substrate having a length of 200 mm, a width of 10 mm and a thickness of 2 mm and an alumina content of 96 wt% was prepared. A straight groove was provided along the length direction of the substrate on the end face portion having a convex curved surface in the length direction of the substrate. The straight groove was formed such that the center of the groove in the width direction coincides with the center of the end face in the thickness direction of the substrate, and the bottom surface of the straight groove is flat and orthogonal to the main surface.
Further, the straight groove was ground to have a width of 1 mm and a depth of 0.1 mm over the entire length of the substrate of 200 mm. On the other hand, a glass paste obtained by mixing glass powder (GA-1, manufactured by Nippon Electric Glass Co., Ltd.), ethyl cellulose and terepionel was prepared. This glass paste was filled in the above-mentioned straight groove by printing, dried at 150 ° C, and then dried at 950 ° C for 3 hours.
Bake for 0 minutes. By properly adjusting the glass paste, the surface of the glaze layer could be projected with a radius of curvature smaller than the radius of curvature of the end face, as shown in FIG. 2, without flowing from the upper end of the straight groove to the end face.

The layer thickness distribution in the groove width direction of the glaze layer buried in the straight groove is 0.03 mm to 0.06 mm in the conventional one as compared with the conventional one shown in FIG. On the other hand, in the present embodiment, it is 0.110 ± 0.005.
mm, and the variation was extremely small. Further, the layer thickness distribution of the glaze layer in the substrate length direction, that is, the glaze waviness was 2 to 5 μm in the conventional example shown in FIG. 3, but is 1 μm or less in this example, and is extremely uniform. there were.

[0013]

As described above, according to the present invention, a straight groove is provided along the lengthwise direction of the substrate on the end surface forming the convex curved surface of the ceramic substrate, and the layer surface has the convex curved surface. Since the glaze layer forming the is embedded, when printed or printed using the substrate of the present invention in the thermal head, it can be applied to rough plain paper or hard paper in good and high speed without causing unevenness in density or lines. It can be printed or printed. Further, in the thin film process for providing the electrodes on the substrate, the disconnection failure of the wiring is almost eliminated, and the yield of the substrate can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional perspective view of a main part of a substrate for an end surface type thermal head according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part thereof.

FIG. 3 is a sectional view of FIG.

FIG. 4 is a sectional view corresponding to FIG. 3 showing a substrate for an end surface type thermal head of a conventional example.

[Explanation of symbols]

 11, 12 Main surface 13 End surface 14, 14 'Glaze layer 15 Ceramic substrate 16 Straight groove 16a Bottom surface of straight groove

Claims (4)

[Claims] 1. A ceramic substrate (1) having a pair of main surfaces (11, 12) facing each other and an end surface (13) adjacent to these main surfaces.
5) and a glaze layer (14) formed on the end face (13), in the end face type thermal head substrate, the ceramic substrate (15) is formed on the end face (13) forming a convex curved surface.
The straight groove (16) is formed along the length direction of the straight groove (16)
An end face type thermal head substrate characterized in that a glaze layer (14, 14 ') having a convex curved surface is embedded in the layer. 2. The bottom surface (16a) of the straight groove (16) is flat,
The end face type thermal head substrate according to claim 1, which is orthogonal to the main surface (11, 12). 3. The substrate for an end face type thermal head according to claim 1, wherein the glaze layer (14 ′) is embedded in the straight groove (16) such that the surface of the layer is a surface protruding from the end face (13). 4. The end face type thermal head according to claim 1, wherein the center of the straight groove (16) in the width direction is provided so as to coincide with the center of the end face (13) of the ceramic substrate (15) in the thickness direction. substrate.