JPH05270031A - Substrate for end surface type thermal head - Google Patents

Abstract

PURPOSE:To enhance printing efficiency and to prevent the generation of color irregularity or streakiness by more enhancing the flatness of the surface of a glaze layer. CONSTITUTION:In a substrate for an end surface type thermal head equipped with a ceramic substrate 15 having a pair of mutually opposed main surfaces and the end surface 13 formed into a protruding curved surface so as to continue to the main surfaces and the glaze layer 14 formed to the end surface 13 or the end surface 13 and one main surface, a step 16 having the width (h) corresponding to the thickness (t) of the glaze layer 14 is formed to the end surface boundary part continuing to each of the main surfaces 11 where no glaze layer 14 is formed in the length direction of the substrate 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a thermal head of a thermal transfer printer. More specifically, it relates to an end face type thermal head substrate in which a glaze layer is formed on the end face of a ceramic substrate.

[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 the end face of the substrate, the flatness of the heating resistor portion is improved, and the head is used for recording paper on the platen roller. Contact evenly. As a result, this type of thermal head is able to print well on rough paper such as plain paper and hard paper such as cards, with the addition of heat storage and heat dissipation of the glaze layer, and the recording unit is compact and lightweight. Can be converted. Conventionally, in order to further improve the printing quality and improve the printing efficiency, it is known that the end face of the end face type thermal head substrate has a convex curved surface. As shown in FIG. 5, in this end face type thermal head substrate, the end face 3 following the main surface 1 of the ceramic substrate 5 is formed into a convex curved surface to reduce the radius of curvature of the glaze layer 4 formed on the end face 3. It has been devised.

[0003]

However, in the above-mentioned conventional thermal head substrate, when the glass paste is applied to the end surface 3 of the convex curved surface and the glass paste is baked to form the glaze layer 4, the end surface is not formed. The molten glass easily flows down from the boundary to the main surface 1. This glass flow-down occurs when the glass pool 6 formed by melting at the end face boundary portion becomes too large. This phenomenon partially occurs at the boundary portion of the end face extending in the length direction of the substrate 5, and the amount of the flow down is not constant. In the conventional substrate structure having a convex curved end face, it was difficult to control the degree of accumulation of glass at the end face boundary portion. For this reason, the glass flow-down partially occurs at the boundary of the end faces, and if the flow-down amount varies, the thickness of the glaze layer 4 at the portion that has flowed down to the main surface 1 becomes small, which is a cause of the undulation near the top of the glaze layer It has become. If you print with a thermal head that has a heating resistor formed on the swelled glaze layer, the heat generated by the resistor cannot be stored uniformly in the glaze layer, and the heat dissipation during printing will be uneven, resulting in uneven colors. Problems such as line sticking occur. An object of the present invention is to provide a substrate for an end face type thermal head, which has a higher flatness on the surface of the glaze layer, has high printing efficiency, and does not cause color unevenness or line-splitting during printing.

[0004]

In order to achieve the above object, the structure of the present invention will be described with reference to FIGS. 1 and 2.
The present invention is directed to a ceramic substrate 15 having a pair of principal surfaces 11 and 12 facing each other and an end surface 13 formed on the convex curved surface following these principal surfaces, an end surface 13 or an end surface 13 and one main surface 12. And an end face type thermal head substrate having a glaze layer 14 formed on the substrate. The characteristic structure is that the step 16 having a width h corresponding to the thickness t of the glaze layer 14 is formed in the longitudinal direction of the substrate 15 at the end face boundary portion following the main surface 11 on which the glaze layer 14 is not formed. Especially.

The present invention is not limited to the one in which the glaze layer 14 is formed only on the end surface 13 of the ceramic substrate 15 as shown in FIG. 2, but as shown in FIG.
One in which the glaze layer 14 is formed on one main surface 12 is included. As shown in FIG. 4, when the width h of the step 16 is made wider than the thickness t of the glaze layer 14, the vicinity of the end face boundary portion is recessed from the main surface 11, and when wiring is provided on this, wiring breakage or the like occurs. Not preferable. Although not shown, if the step width is made narrower than the thickness of the glaze layer, the molten glass may flow down from the end face boundary portion to the main surface as in the conventional case, which is not preferable. Therefore, as shown in FIG. 1, the step 16 is formed to have a width h corresponding to the thickness t of the glaze layer 14. This step is formed by simultaneously grinding the end surface of the sintered ceramic substrate into a convex curved surface, or by extruding so that the end surface boundary portion of the ceramic green sheet becomes stepped. ..

[0006]

By forming step 16 at the end face boundary portion, when the glass paste for forming the glaze layer is fired, the molten glass is stopped at step 16 and does not flow down from the end face boundary portion to the main surface 11. Step 16
By matching the width h of the glaze layer with the thickness t of the glaze layer 14, the glaze layer 14 fills the step 16 without excess or deficiency,
No step is formed between the glaze layer 14 and the main surface 11 at the end face boundary portion.

[0007]

The present invention will be described in detail below with reference to examples. The invention is not limited to this example. 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% was prepared. The entire flat end face in the length direction of this substrate was ground to form a convex curved surface, and at the same time, steps were formed at the end face boundary portion. In this example, the radius of curvature of both shoulders of the end face is 1.2 mm, and the step width is 10 μm. Glass powder [G
A-1, manufactured by Nippon Electric Glass Co., Ltd.], a glass paste obtained by mixing ethyl cellulose and terpineol was applied by spraying, the glass paste was dried at 150 ° C., and then baked at 950 ° C. for 30 minutes. .. The glass paste was applied to such an extent that the steps were filled with the glass paste. At the end face boundary part of the obtained ceramic substrate,
There was no flow of glass from the end surface to the main surface, and no step was formed between the glaze layer and the main surface. When the waviness of the surface of the glaze layer in the vicinity of the top of the end face was measured by a surface roughness meter, it was 2 μm to 5 μm in the conventional example in which no step was formed, but it was 1 μm or less in this example.

[0008]

As described above, according to the present invention, a step having a width corresponding to the thickness of the glaze layer is formed in the end face boundary portion following the main surface on which the glaze layer is not formed. Since it was formed in step 1, the molten glass when forming the glaze layer is dammed in steps and does not flow down to the main surface. As a result, the waviness of the surface of the glaze layer is eliminated, and the heat storage and heat dissipation of the glaze layer are performed uniformly, so that printing defects such as color unevenness and line drawing during thermal transfer printing are eliminated.

[Brief description of drawings]

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

FIG. 2 is a perspective view of a main part thereof.

FIG. 3 is a cross-sectional view of a main part of another end surface type thermal head substrate of the present invention.

FIG. 4 is a sectional view corresponding to FIG. 1 when the step width is wider than the thickness of the glaze layer.

FIG. 5 is a sectional view corresponding to FIG. 1 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 glaze layer 15 ceramic substrate 16 steps

Claims (1)

[Claims] 1. A ceramic substrate (15) having a pair of principal surfaces (11, 12) facing each other and an end surface (13) formed on the convex curved surface following these principal surfaces, and the end surface (13). ) Or the end face (1
3) and a glaze layer (14) formed on one main surface (12), wherein the end surface type thermal head substrate is an end surface following the main surface (11) on which the glaze layer (14) is not formed Width (h) corresponding to the thickness (t) of the glaze layer (14) at the boundary
A substrate for an end face type thermal head, characterized in that the step (16) having the above is formed in the length direction of the substrate (15).