JPH04244862A - Thermal head - Google Patents

Abstract

PURPOSE:To provide a thermal head having relatively good printing efficiency and improved in the release from a ribbon. CONSTITUTION:In a thermal head wherein a resistance film layer 3 is formed to the glaze layer 2 on an insulating substrate 1 and a common electrode 5 and individual electrodes 6 are formed to the resistance film layer 3 so as to provide the interval for forming a heating part 4 and a protective film 7 is formed so as to cover the heating part 4, the common electrode 5 and the individual electrodes 6, the heating part 4 is formed to the inclined part 24 provided to the glaze layer 2 so as to be successively reduced in thickness toward the end edge of the glaze layer 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head with improved printing efficiency.

0002

2. Description of the Related Art Conventional thick film thermal heads include partial glaze type, double partial glaze type, and true edge type. As shown in FIG. 9, the partial glaze type thermal head has a resistive film layer 3 formed on the upper surface of the end of a substrate 1 on a partial glaze layer 2 with a width of about 300 to 1200 μm and a curvature. In order to form a heat generating part 4 on the top of the glaze layer 2 of the film layer 3, a common electrode 5 and an individual electrode 6 are formed on both sides with the top of the glaze layer 2 placed, and the upper surface is further covered with a protective film 7. It is something that Further, in the double partial glaze type thermal head, as shown in FIG. 10, only the lower glaze layer 2a of the partial glaze type heat generating part 4 is raised into a convex shape by glaze etching or the like.

[0003] A true edge type thermal head is shown in Figure 11.
As shown in the figure, a glaze layer 2 and a heat generating part 4 are provided on the end surface of a substrate 1. In addition, as a modification, as shown in FIG. 12, a part of the edge of the substrate 1 is cut diagonally, and glaze layers 2A, 2B, and 2C are formed not only on the upper surface 1A of the substrate 1 but also on the slope 1B and the end surface 1C. , there is one in which a heat generating portion 4 is formed on the slope 1B.

0004

[Problem to be solved by the invention] In the thermal head,
In order to print on rough paper and improve printing efficiency, it is necessary to concentrate the pressure of the heating resistor on the ribbon, transfer paper, and platen. As shown in FIG. 13, in the partial glaze type, the glaze layer 2 having the heat generating part 4 comes into contact with the platen rubber 10 over a wide area via the ink ribbon 8 and the transfer paper 9, and the pressure on the heat generating part 4 is concentrated. The problem is that it is not possible to obtain enough. This problem can be solved to some extent by using the true edge type. However, in the true-edge type shown in FIG. 11, the current substrate thickness is about 2 mm, which is rather thick, and the original characteristics of the true-edge type cannot be fully exhibited. Also, a point common to the thermal heads shown in Figures 11 and 12 is that the side edges of the substrate are processed and printing is performed on the edges, so it is not possible to take out many pieces at once from a large substrate. As a result, there was a problem in that the cost per piece increased. In order to solve this problem, the applicant of the present application has already proposed a thermal head in which heat generating parts are formed in the corner parts of the glaze layer. However, forming the heat-generating part across the corner allows pressure to be concentrated on the heat-generating part, but it is difficult to form a conductor pattern for the common electrode on the side surface when the corner is at a right angle. However, if the angle of the corner part is obtuse, there remains the problem that ribbon peeling is difficult (it takes a long time to peel off the ribbon) depending on the size of the slope part. Further, if the heating element is formed at a corner, it is difficult to control the resistance value, and there is also the problem that the yield decreases.

[0005] The present invention has been made in view of the above-mentioned problems, and the object of the invention as claimed in claim 1 is to provide a thermal head that has a certain degree of printing efficiency and good ribbon peeling. The second invention aims to provide a thermal head that has a certain degree of printing efficiency and is easy to pattern.

[0006]

Means for Solving the Problems and Effects The thermal head according to claim 1 of the present invention includes a glaze layer formed on an insulating substrate, a resistive film layer formed on the glaze layer, and a resistive film layer formed on the resistive film layer. A common electrode and individual electrodes are formed at intervals that form a heat generating part, and a protective film layer is formed to cover the heat generating part, the common electrode and the individual electrodes,
The glaze layer is provided with a sloped portion whose thickness gradually decreases toward the edge, and a heat generating portion is formed in this sloped portion.

[0007] In this thermal head, since most of the heat generating portions are formed on the inclined portions, the distance from the heat generating portion to the side surface of the edge of the substrate is small, and the ink ribbon is easily peeled off. In the thermal head according to claim 2 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 common heat-generating portion is formed at intervals on the resistive film layer. In a device in which an electrode and an individual electrode are formed, and a protective film layer is formed to cover the heat generating part, the common electrode, and the individual electrode, the heat generating part is formed shifted toward the center of the substrate from the corner part of the glaze layer. ing.

In this thermal head, most of the heat generating parts are formed on the upper surface of the glaze layer, so even if the angle of the corner part is a right angle, the pattern part formed on the side surface of the glaze layer becomes small and its This makes pattern formation easier.

[0009]

[Examples] The present invention will be explained in more detail with reference to Examples below. FIG. 1 is a sectional view of a main part of a thermal head showing an embodiment of the present invention. The thermal head of this embodiment has a substrate 1 on which an underglaze layer 2 is formed.
The basic structure in which the resistive film layer 3, common electrode 5, and individual electrodes 6 are formed and further covered with a protective film 7 is not particularly different from the conventional one.

The feature of the thermal head of this embodiment is that the end of the glaze layer 2 is cut diagonally to provide an inclined surface 24.
The heat generating portion 4 is formed on the edge side of the corner portion 23 where the upper surface 21 and the inclined surface 24 intersect, that is, on the inclined surface 24. That is, the resistive film layer 3 is formed from the upper surface 21 of the glaze layer 2 to the inclined surface 24, and the common electrode 5 is formed on the edge side of the inclined surface 24 of the glaze layer 2, and the common electrode 5 is formed individually from the upper surface 21 of the glaze layer 2 to the corner portion 23. The electrode 6 is formed, and the heat generating part 4 is located closer to the edge than the corner part 23.

This thermal head has a heat generating part 4 formed on the inclined surface 24 on the edge side of the corner part 23 of the glaze layer 2, so when the platen is pressed through thermal paper, ribbon, etc., a certain amount of pressure is generated. can be applied to the heat generating part 4 in a concentrated manner, and since the heat generating part 4 is provided at the edge of the substrate 1, ribbon peeling is improved. In the thermal head of this embodiment, as shown in FIG.
By forming the common electrode 5b, the width of the folded common electrode 5b can be reduced, the heat generating part 4 can be further tightened toward the edge side, and ribbon peeling can be improved. If this folded common electrode 5b is made as small as possible and ultimately eliminated and made a part of the heat generating resistor 3 as shown in FIG. becomes almost 0, and the ribbon peels off easily.

Next, a method of manufacturing the thermal head of the above embodiment will be explained. First, as shown in FIG. 5, a ceramic substrate 1 on which a glaze layer 2 is formed is half-cut to a depth d exceeding the thickness of the glaze layer 2 to form a groove 11. This groove 11 has an inverted trapezoidal shape so that the angle α of the corner portion 23 of the glaze layer 2 is an obtuse angle. As a result, an inclined surface 24 is formed at the end of the glaze layer 2. However, in this embodiment, the depth d exceeds the thickness of the glaze layer 2, but depending on the case, the depth d may not exceed the thickness of the glaze layer 2. For example, this is the case when the glaze layer is thick or the inclination angle is large (obtuse angle). In addition,
Although not shown, the substrate 1 is a large substrate that can accommodate a large number of thermal heads, and a plurality of grooves 11 are formed in the substrate.

[0013] At the time of the above half-cut, the glaze layer 2
Since chips and burrs remain on the corner portions 23 and the surface smoothness is low, the substrate 1 is then heat treated at 800°C. As a result, the corner portion 23 of the glaze layer 2 has a curvature and roundness as shown in FIG. 6, and the smoothness of the surface is also improved, making subsequent pattern formation easier.

Subsequently, after heat treatment, a resistive film layer 3, a common electrode 5, and an individual electrode 6 are formed, a well-known pattern is formed in a photolithography process, and a protective film 7 is formed. Then, as shown in FIG. 7, a substrate before division is obtained. Finally, it is cut and divided along line AA in FIG. 7 to obtain individual thermal heads 12 shown in FIG. 8. Through the above steps, the thermal head shown in FIG. 1 is completed.

In this manufacturing method, the glaze layer 2 is half-cut and the corner portions 23 are formed at an obtuse angle, so the process is no different from that of a normal flat head, and a large number of thermal heads can be processed at the same time. Figure 4 shows
FIG. 7 is a sectional view of a main part of a thermal head showing another embodiment of the present invention. The thermal head of this embodiment has a basic structure in which a resistive film layer 3, a common electrode 5, and an individual electrode 6 are formed on a substrate 1 on which an underglaze layer 2 is formed, and is further covered with a protective film 7, compared to the conventional one. There is nothing particularly different.

The feature of this embodiment of the thermal head is that the corner portion 23 where the upper surface 21 and side surface 22 of the glaze layer 2 intersect
This is because the heat generating portion 4 is formed shifted closer to the center of the substrate. That is, the resistive film layer 3 is formed from the upper surface 21 of the glaze layer 2 to the side surface 22, and the common electrode 5 is formed from the upper end of the side surface 22 of the glaze layer 2.
1, the individual electrodes 6 are formed leaving the edge side, and the corner part 2 is formed.
3, the heat generating portion 4 is located at a location shifted toward the center of the board.

In this thermal head, the heat generating part 4 is formed at a position shifted toward the center from the corner part 23 of the glaze layer 2, so when the platen is pressed through thermal paper, ribbon, etc., a certain amount of pressure is generated. In addition to being able to concentrate the heat on the heat generating part, most of the heat generating part is formed on the upper surface 21 of the glaze layer 2, and the common electrode is also formed from the upper edge of the side surface, so patterning is easy.

The method for manufacturing this thermal head is almost the same as the method described with reference to FIGS. 5 to 8, except that the grooves 11 are made rectangular in cross-section, so a description thereof will be omitted.

[0019]

According to the invention as claimed in claim 1, an inclined surface is provided at the end of the glaze layer, and the heating portion is formed on this inclined surface on the edge side of the corner portion, so that the heating portion is located at the edge of the substrate. Since it is placed closer to the edge, it is possible to shorten the stretching time of the ink ribbon and increase the peeling angle, making it very effective when used with ink ribbons where the peeling time and angle have a large effect.

According to the second aspect of the invention, since the heat generating portion is formed at a position shifted from the corner portion of the glaze layer toward the center of the substrate, most of the heat generating portion is formed on the upper surface of the glaze layer, so that patterning is easy. It becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a thermal head according to an embodiment of the present invention.

FIG. 2 is a plan view showing an example of a pattern of a thermal head according to an embodiment of the present invention.

FIG. 3 is a plan view showing another pattern example of the thermal head according to the embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a thermal head according to another embodiment of the present invention.

FIG. 5 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. 6 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. 7 is a sectional view of an intermediate product after formation of a protective film and before individual division for explaining the method of manufacturing a thermal head according to an embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a thermal head after being divided into individual parts for explaining a method of manufacturing a thermal head according to an embodiment of the present invention.

FIG. 9 is a partial cross-sectional view showing an example of a conventional thermal head.

FIG. 10 is a partial sectional view showing another example of a conventional thermal head.

FIG. 11 is a partial sectional view showing another example of a conventional thermal head.

FIG. 12 is a partial sectional view showing another example of a conventional thermal head.

FIG. 13 is an explanatory diagram for explaining a problem with a conventional thermal head.

[Explanation of symbols]

1 Board 2 Glaze layer 3 Resistive film layer 4 Heat generating part 5 Common electrode 6 Individual electrodes 7 Protective film 23 Corner section 24 Slope surface

Claims (2)

[Claims] Claim 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 individual electrodes are formed at intervals such that a heat generating portion is formed on the resistive film layer. , in the thermal head in which a protective film layer is formed covering the heat generating part, the common electrode and the individual electrodes, the glaze layer is provided with an inclined part whose thickness becomes thinner in sequence toward the edge; A thermal head characterized in that a heat generating part is formed in an inclined part. 2. A glaze layer is formed on an insulating substrate, a resistive film layer is formed on the glaze layer, and a common electrode and individual electrodes are formed at intervals such that a heat generating portion is formed on the resistive film layer. , in the thermal head in which a protective film layer is formed covering the heat generating part, the common electrode, and the individual electrodes, the heat generating part is formed to be shifted toward the center of the substrate from the corner part of the glaze layer. thermal head.