JP2647270B2 - Thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inexpensive thermal head having good printing efficiency.

[0002]

2. Description of the Related Art Conventional thick film thermal heads include a partial glaze type, a double partial glaze type, and a true edge type. As shown in FIG. 6, the partial glaze type thermal head forms a resistive film layer 3 on a curved partial glaze layer 2 having a width of about 300 to 1200 μm on an upper surface of an end portion of a substrate 1. In order to form the heat generating portion 4 on the top of the glaze layer 2 of the layer 3, a common electrode 5 and an individual electrode 6 were formed on both sides with the top of the glaze layer 2, and the upper surface thereof was covered with a protective film 7. Things.
Further, as shown in FIG. 7, the double partial glaze type thermal head is one in which only the glaze layer 2a under the partial glaze type heat generating portion 4 is raised in a convex shape by glaze etching or the like.

[0003] As shown in FIG. 8, a thermal edge type thermal head has a glaze layer 2 and a heat generating portion 4 on an end face of a substrate 1.
Is provided. As a modification, as shown in FIG. 9, the edge of the substrate 1 is partially cut obliquely, and the glaze layer 2 is formed not only on the upper surface 1 _A of the substrate 1 but also on the slope 1 _B and the end surface 1 _C.
A, 2 _B, to form a 2 _C, the slope 1 _B, there is formed a heat generating portion 4.

[0004]

SUMMARY OF THE INVENTION In a thermal head,
In order to print on rough paper and to improve the printing efficiency, it is necessary to concentrate the pressure of the heating resistor on the ribbon, the paper to be transferred, and the platen. As shown in FIG. 10, the partial glaze type has a wide range of contact with the platen rubber 10 via the glaze layer 2 having the heat generating portion 4, the ink ribbon 8 on the substrate portion near the heat generating portion 4, and the transfer paper 9, There is a problem that the pressure concentration of the heat generating portion 4 cannot be sufficiently obtained. This problem can be solved to some extent by the edge-to-edge type. However, in the case of the tool-edge type shown in FIG. 8, the current substrate thickness is as thick as about 2 mm.
The original features of the true edge type cannot be fully exhibited. 8 and 9 are common to the thermal heads shown in FIGS. 8 and 9 in that they are processed on the side end surface of the substrate and printed on the end surface during manufacturing. In addition, it is necessary to perform patterning, and it is not possible to take many pieces at once from a large substrate. As a result, pressure is concentrated on the heat generating part, and if a thermal head with good printing efficiency is to be obtained, it takes time and effort to manufacture, and the manufacturing cost is high. There is a problem in that it is expensive and the cost of one thermal head increases.

The present invention has been made in view of the above problems, and has as its object to provide a thermal head having high printing efficiency and low manufacturing cost per unit.

[0006]

According to the thermal head of the present invention, a glaze layer is formed on an insulating substrate, a resistive film layer is formed on the glaze layer, and a heating section is formed on the resistive film layer. A common electrode and an individual electrode are formed at intervals, and a protective film layer is formed to cover the heating section, the common electrode and the individual electrode, wherein the glaze layer is formed on a flat surface on an insulating substrate. It has a bulge protruding from a flat surface adjacent to the edge of the insulating substrate, the bulge is continuous in a curved surface from the side surface of the glaze layer located at the edge of the insulating substrate to the flat surface, A resistive film layer is formed on a flat surface of the glaze layer and a curved surface of the bulging portion; the common electrode is provided on a resistive film layer portion on a side surface of the glaze layer located at an edge of the insulating substrate; Is on the flat surface up to the bulge of the glaze layer Provided in the layer portion, wherein the heating portion is placed in the exposed portions of the resistive film on the bulge portion of the glaze layer.

According to this thermal head, since a heat generating portion is formed at the bulging portion of the glaze layer formed adjacent to the edge of the insulating substrate, printing can be performed without making the thermal head oblique as shown in FIG. In addition to being able to perform printing, pressure is concentrated on the heat-generating portion, and the heat-generating portion efficiently prints on the printing medium (transferred) regardless of whether the printing is performed with the thermal head inclined or not. Paper). Moreover, since the common electrode is located on the side surface of the bulging portion,
Even if the thermal head is not inclined, the common electrode does not contact the print medium during printing.

[0008]

The present invention will be described in more detail with reference to the following examples. FIG. 5 is a sectional view of a main part of a thermal head according to an embodiment of the present invention. This thermal head is
A resistive film layer 3, a common electrode 5, and an individual electrode 6 are formed on a ceramic substrate 1 on which an underglaze layer 2 is formed on the upper surface, and these layers are further covered with a protective film 7. There is no particular difference from well-known ones.

The feature of this thermal head is that the underglaze layer 2 is formed on the substrate 1 on a flat surface, and has a bulging portion 25 protruding from the flat surface adjacent to the edge of the substrate 1. A portion 25 continues in a curved shape from the side surface 22 of the glaze layer 2 located at the edge of the substrate 1 to the flat surface (upper surface) 21;
The resistive film layer 3 is formed on the flat surface 21 of the glaze layer 2 and the curved surface of the bulging portion 25, and the common electrode 5 is located on the side surface 22 of the glaze layer 2 located at the edge of the substrate 1. , The individual electrode 6 is provided in the portion of the resistive film layer 3 on the flat surface 21 up to the bulging portion 25 of the glaze layer 2, and the heat generating portion 4 is provided on the bulging portion 25 of the glaze layer 2. This is to be an exposed portion of the resistive film layer 3. Next, an example of manufacturing the thermal head of the above embodiment will be described.

First, as shown in FIG. 1, a ceramic substrate 1 having a glaze layer 2 formed on the upper surface is half-cut over a depth d exceeding the thickness of the glaze layer 2 to form a groove 11. The groove 11 has a rectangular cross section so that the angle α of the corner portion 23 of the glaze layer 2 is a right angle. Although the depth d exceeds the thickness of the glaze layer 2 in this embodiment, the depth d may not exceed the thickness of the glaze layer 2 in some cases. For example, when the glaze layer is thick. Although not shown, the substrate 1 is a large substrate from which a large number of thermal heads can be formed.
1 is formed in a plurality.

At the time of the half cut, the glaze layer 2
Since chips and burrs remain in the corner portions 23 and the surface smoothness is low, the substrate 1 is heat-treated at a high temperature of about 900 °. As a result, as shown in FIG. 2, the groove end 2a of the glaze layer 2 swells upward due to surface tension, has a curvature, has a rounded corner, and has an improved surface smoothness. The pattern formation subsequent to the above becomes easy.
By the high-temperature treatment, the namali component is removed from the non-crystalline glass of the glaze layer 2, and the curvature R is 10 at 900 °.
At 0, a bulge with a height of 7μ is obtained.

Subsequently, after a high-temperature heat treatment, a resistive film layer 3, a common electrode 5, and an individual electrode 6 are formed, and a well-known pattern is formed by a photolithography process. The film is obtained to obtain the undivided substrate as shown in FIG. Finally, the individual thermal head 1 shown in FIG. 4 is divided by dicing from the line AA in FIG.
Get 2. By completing the above steps, the thermal head of FIG. 5 is completed.

In this manufacturing method, the glaze layer 2 is half-cut to form a rectangular groove in a sectional view and the bulge 25 at the end is formed at the end, so that the process is no different from a normal flat head. A large number of thermal heads can be processed easily and simultaneously. In the above embodiment, the shape of the groove is rectangular in cross section, but the glaze edge swells equally even if a certain angle is given and half-cutting is performed. If so, it may have a slight angle. Further, in the above-described embodiment, an example is shown in which the entire glaze type substrate is used. However, the present invention can be applied to a case where a partial glaze type substrate is used.

[0014]

According to the present invention, as described above, the glaze layer is formed on the insulating substrate on a flat surface, and has a bulge protruding from the flat surface adjacent to the edge of the insulating substrate.
The bulging portion continues in a curved shape from the side surface to the flat surface of the glaze layer located at the edge of the insulating substrate, and a heating portion is formed in the bulging portion. In addition to being able to print even when printing with the thermal head inclined, or when printing without the inclination, pressure concentrates on the heating part,
The heating section efficiently contacts the print medium (transferred paper). Moreover, since the common electrode is located on the side of the resistive film layer on the side of the glaze layer, the common electrode does not come into contact with the print medium during printing even if the thermal head is not inclined. In addition, the print ribbon is easily separated from the head, and the print ribbon and the print medium are not damaged. Further, when forming the common electrode or the individual electrode, the pattern is hardly cut.

[Brief description of the drawings]

FIG. 1 is a sectional view of an intermediate product for explaining a method of manufacturing a thermal head according to an embodiment of the present invention.

FIG. 2 is a sectional view of an intermediate product for explaining a method of manufacturing the thermal head according to the present invention.

FIG. 3 is a sectional view of an intermediate product after formation of a protective film and before individual division for explaining a method of manufacturing the thermal head of the present invention.

FIG. 4 is a cross-sectional view showing the thermal head after individual division for describing a method of manufacturing the same thermal head of the present invention.

FIG. 5 is a sectional view of a principal part of the thermal head according to the embodiment of the present invention.

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

FIG. 7 is a partial sectional view showing another example of a conventional thermal head.

FIG. 8 is a partial sectional view showing another example of a conventional thermal head.

FIG. 9 is a partial sectional view showing another example of a conventional thermal head.

FIG. 10 is an explanatory diagram for explaining a problem of a conventional thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Glaze layer 3 Resistance film layer 4 Heating part 5 Common electrode 6 Individual electrode 7 Protective film 25 Swelling part

Claims (1)

(57) [Claims] 1. A glaze layer is formed on an insulating substrate, a resistive film layer is formed on the glaze layer, and a common electrode and an individual electrode are formed on the resistive film layer at intervals to form a heat generating portion. , the heating unit, the thermal head protective film layer to cover the common electrode and the individual electrodes are formed, the glaze layer is formed on the flat surface on an insulating substrate, a flat surface adjacent to the insulating substrate edge It has a bulge raised from the swollen portion of the glaze layer located on the insulating substrate edge
The resistance film layer is formed on the flat surface of the glaze layer and the curved surface of the bulging portion , and the common electrode is formed on the side surface of the glaze layer located at the edge of the insulating substrate.
The individual electrodes are provided on a resistive film layer portion located on a flat surface up to the bulge portion of the glaze layer, and the heating portion is provided on the resistive film layer portion on the bulge portion of the glaze layer. A thermal head, characterized in that the layer is exposed.