JPH0746539Y2 - Thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Use The present invention relates to a thermal head used in a facsimile or the like.

(B) Conventional Technique FIG. 4 is a plan view showing a main part of a conventional edge-type (a large number of heating dots are arranged in parallel at one end of an insulating substrate) thermal head.

In this thermal head, a glaze layer (heat storage layer) is provided on the upper surface of an insulating substrate (alumina ceramic substrate) 1, and a common electrode pattern 3 and an individual electrode pattern 7 are formed on this glaze layer.
And are alternately arranged in sequence so as to face each other, and a heating resistor 4 parallel to the end of the insulating substrate 1 is provided between the common electrode pattern 3 and the individual electrode pattern 7, and the substrate 1 and the heating resistor 4 are provided.
The protective film 6 is formed on the surfaces of the lead patterns (common electrode pattern 3 and individual electrode pattern 7).

The thermal head applies a pulse voltage between the lead patterns (individual electrodes 7 and common electrode 3) to selectively generate heat in the heating resistors 4, thereby forming thermal paper (thermal ribbon) on the heating resistors 4. Information is printed on the recording paper that is fed under pressure in the superposed state.

(C) Problems to be Solved by the Invention In the above-mentioned edge-type thermal head, the heating resistor is arranged in parallel in the vicinity of one end of the insulating substrate. Further, from the viewpoint of printing, it is desired to dispose the heating resistor as close as possible to one edge of the insulating substrate. However, the common electrode pattern is located between the heating resistor and one end of the insulating substrate. Therefore, the width of the common electrode pattern becomes narrower as the heating resistor is arranged closer to one end of the insulating substrate. Then, when the width of the common electrode pattern becomes narrow, the common resistance increases and a voltage drop occurs, resulting in poor print quality.

Therefore, in recent years, a thermal head as shown in FIG. 5 has been implemented.

In this thermal head, the heating resistor 4 is brought as close as possible to one end of the insulating substrate 1 to reduce the common resistance on the narrowed common electrode pattern 3 (parallel to one end of the insulating substrate). To form the auxiliary conductor 5 for. However, in this thermal head, the auxiliary conductor 5 portion largely bulges upward, and as a result, at the time of printing, the platen roller 9 hits the auxiliary conductor 5 and an appropriate pressure is not applied to the dot portion, resulting in a disadvantage that the printing becomes thin. there were.

Therefore, the applicant of the present application has previously proposed a thermal head that achieves downsizing of the head and that the auxiliary conductor portion does not largely swell, as shown in FIG. This thermal head is formed by excluding a part of the glaze layer 2, that is, a part of the region in which the common electrode pattern 3 is formed and close to the heating resistor 4 (notched by a certain width), A groove-shaped recess 21 is provided. The auxiliary conductor 5 is provided on the common electrode pattern 3 including the groove-shaped recess 21.

In this thermal head, the auxiliary conductor 5 is formed on the common electrode pattern 3 and over the portion with the glaze layer 2 and the portion without the glaze layer 21 (the groove-shaped concave portion 21), and a part thereof is groove-shaped. The height of the auxiliary conductor 5 is suppressed as a whole by the amount of depression into the concave portion 21, and as a result, it can be made substantially the same as the height of the heating resistor 4. Therefore, in this thermal head, since the common electrode pattern 3 is narrowed, the heating resistor 4
Can be brought closer to the edge of the substrate, miniaturization can be achieved, common resistance can be reduced, and printing quality can be improved. Further, by suppressing the bulging height of the auxiliary conductor 5, there is an effect that uniform dark and light printing can be executed by uniform pressing.

However, since this thermal head completely removes (cuts) a part of the glaze layer 2,
When the common electrode pattern is formed by patterning on the upper layer including the removed portion (groove 21), the step between the bottom of the groove 21 and the upper surface of the glaze layer 2 is large, and the opening edge of the groove 21, that is, Since the edge portion is substantially vertical to the upper surface of the glaze layer 2, the common electrode pattern 3 corresponding to this portion has an extremely thin film shape A. Therefore, there is a problem that the thin film portion of the common electrode pattern 3 may be cut, and there is a disadvantage that the electric resistance may increase.

An object of the present invention is to provide a thermal head which solves the problems described above, achieves miniaturization of the head, does not swell the auxiliary conductor, and does not cut a part of the common electrode pattern. And

(D) Means and Actions for Solving the Problem In order to achieve this object, the thermal head of the present invention has the following configuration.

The thermal head is provided with a glaze layer on the upper surface of the insulating substrate, and a narrow common electrode pattern and individual electrode pattern are arranged on this glaze layer, and the insulating substrate is provided between the common electrode pattern and the individual electrode pattern. A thermal head in which a heat generating resistor parallel to the end is provided, and an auxiliary conductor for reducing the common resistance is provided in the narrow common electrode pattern, and the common electrode pattern is formed in the glaze layer. In this region, a part of the side close to the heating resistor is formed in a thin curved shape, and the auxiliary conductor is provided in an upper layer including the thin curved concave portion.

In the thermal head having such a configuration, when the auxiliary conductor is provided on the common electrode pattern, the glaze layer on the side where the common electrode pattern is formed and closer to the heating resistor is formed in a thin curved shape. However, it was decided to provide a curved concave portion having a small thickness. Therefore, the auxiliary conductor is formed on the common electrode pattern and over the thick portion and the thin portion (thin curved concave portion) of the glaze layer, and a part of the auxiliary conductor is formed in the curved concave portion. The height of the auxiliary conductor is suppressed as a whole by the amount of the depression, and as a result, the height can be almost the same as the height of the heating resistor. In addition, since the curved concave portion does not completely remove (notch) the glaze layer but only sets the thickness thin, the step between the bottom surface of the curved concave portion and the upper surface of the glaze layer is not so large, and the opening edge (edge Part) is set to be curved with respect to the upper surface of the glaze layer. Therefore, when the common electrode pattern is patterned on the glaze layer including the curved recess,
The common electrode pattern becomes thin at the peripheral edge portion (edge portion) of the curved concave portion, and there is no fear of cutting.

(E) Embodiment FIG. 1 is a sectional view of a main part showing a specific embodiment of the thermal head according to the present invention.

The thermal head of the embodiment has substantially the same structure as that of the conventional head shown in FIG. That is, an edge type (a large number of heating dots are arranged in parallel at one end of the insulating substrate) head is provided with a glaze layer (heat storage layer) 2 on the upper surface of the insulating substrate (alumina ceramic substrate) 1, and this glaze layer 2 The narrow common electrode patterns 3 and the individual electrode patterns 7 are alternately arranged in sequence on the upper side in an alternating manner, and are arranged in parallel with the end portions of the insulating substrate 1 over the common electrode patterns 3 and the individual electrode patterns 7. The heating resistor 4 is provided, and the protective film 6 is formed on the surfaces of the substrate 1, the heating resistor 4, and the lead pattern (common electrode 3 / individual electrode 7). Also, the heating resistor 4
In order to bring the common electrode pattern 3 closer to one end of the insulating substrate 1 as much as possible, the width of the common electrode pattern 3 is set to be narrow, and the common conductor is reduced on the common electrode pattern 3 as in the conventional example of FIG. 5 is provided.

A feature of the present invention is that, when the auxiliary conductor 5 is provided on the common electrode pattern 3, the glaze layer 2 on the side close to the heating resistor 4 in the region where the common electrode pattern 3 is formed has a thin curved shape. And a thin curved concave portion (21) is provided. The auxiliary conductor 5 is provided so as to include the upper surface of the curved concave portion 21 having a small thickness.

FIG. 2 shows a thin curved concave portion formed in the glaze layer 2.
It is explanatory drawing which shows 21 concrete processing methods. In this embodiment, the glaze layer 2 first forms the first glaze layer 2a having a small thickness (about half the normal thickness). In the first glaze layer 2a, a region in which the common electrode pattern 3 is formed and which is close to the heating resistor 4 is cut out. That is, the removing portion 2b is provided with a cutout having a constant width. Thereafter, the first glaze layer 2a including the removed portion 2b
A second glaze layer (having substantially the same thickness as the first glaze layer 2a) 2c is formed on the upper surface of the. As a result, a thin curved concave portion 21 composed of only the second glaze layer 2c is formed on the removed portion 2b of the first glaze layer 2a.

Further, in the embodiment of FIG. 3A, the curved concave portion 21 is formed in the glaze layer 2 by using two types of glazes (amorphous glazes) having different softening points. That is, in the area where the common electrode pattern 3 is formed, the heating resistor 4 is formed.
The glaze layer 2 is printed by using the glaze portion 2d having a low softening point at a portion close to and the glaze portion 2e having a high softening point at the other portions. After that, it is fired. In this firing step, the glaze part 2d having a low softening point is drawn toward the glaze part 2e having a high softening point (the glass is drawn to the glaze having a low softening point and a high glaze). As a result, the glaze portion 2d having a low softening point becomes a thin curved concave portion 21 as shown in FIG. 3 (B). As shown in FIGS. 2 and 3B, the curved concave portion 21 is thinner than the glaze layer 2 and the opening edge of the concave portion is curved.

In the thermal head having such a configuration, when the auxiliary conductor 5 is provided on the common electrode pattern 3, the thickness of the glaze layer 2 near the heating resistor 4 in the region where the common electrode pattern 3 is formed is reduced. It was formed in a thin curved shape and provided with a thin curved concave portion 21. Therefore, the auxiliary conductor 5 is formed on the common electrode pattern 3 and over the thick portion and the thin portion (the thin curved concave portion 21) of the glaze layer 2, and a part thereof is formed. The height of the auxiliary conductor 5 is suppressed as a whole by the amount of falling into the curved concave portion 21, and as a result, it can be made approximately the same as the height of the heating resistor. Further, the curved concave portion 21 does not completely remove (cut out) the glaze layer 2 but merely sets the thickness thereof thinly. Therefore, the bottom surface of the curved concave portion 21 and the glaze layer 2 are not formed.
The step difference with the upper surface is not so large, and the opening peripheral edge (edge portion) of the concave portion is set to be curved with respect to the upper surface of the glaze layer 2. Therefore, when the common electrode pattern 3 is formed by patterning on the glaze layer 2 including the curved concave portion 21, the common electrode pattern becomes thin at the peripheral edge portion (edge portion) of the curved concave portion 21, and there is no fear of cutting. Absent.

Moreover, since the common electrode pattern 3 is narrowed, the heating resistor 4 can be brought closer to the edge of the insulating substrate 1, and the size can be reduced. Further, the auxiliary electrode 5 provided on the common electrode pattern 3 can reduce the common resistance and improve the printing quality. Further, since the auxiliary conductor 5 falls into the thin curved concave portion 21, the bulging height is suppressed,
Even dark and light printing can be performed by even pressure.

(F) Effect of the device In this device, as described above, the auxiliary conductor for reducing the common resistance is provided on the narrow common electrode pattern, and
The glaze layer is a region where the common electrode pattern is formed, a part of the side close to the heating resistor is formed in a thin curved shape, and an auxiliary conductor is provided on the upper layer including the thin curved concave portion. Therefore, since the common electrode pattern is made narrower, the heating resistor can be brought closer to the edge of the insulating substrate, and the size can be reduced. Also, the common resistance can be reduced by the auxiliary conductor provided on the common electrode pattern, and the printing quality can be improved. Furthermore, since the auxiliary conductor is provided on the common electrode pattern and over the large glaze portion and the thin curved concave portion,
The bulge height of the auxiliary conductor is suppressed by the amount that the auxiliary conductor bulges into the curved concave portion. Therefore, during printing, the auxiliary conductor does not hit the platen roller, and uniform dark and light printing can be performed by uniform pressing. Further, since the step of forming the curved concave portion is not so large as to the upper surface of the glaze layer and the upper edge of the opening is curved to the upper surface of the glaze layer, the common electrode pattern is thinned and cut by the upper edge of the opening of the curved concave portion. There is an excellent effect that the object of the invention is achieved, such as the fear of being eliminated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the main part of the thermal head of the embodiment,
FIG. 2 is an explanatory view showing a state of forming a curved concave portion of the thermal head of the embodiment, FIG. 3 (A) is an explanatory view showing another state of forming the curved concave portion, and FIG. 3 is an explanatory view showing a curved concave portion formed by the forming method of FIG. 3 (A), FIG. 4 is a plan view of a main part of a conventional thermal head, and FIG. 5 is a main part of another conventional thermal head. Sectional view, 6th
The figure is a cross-sectional view of a main part showing a thermal head previously proposed by the applicant of the present application. 1: Insulating substrate, 2: Glaze layer, 3: Common electrode pattern, 4: Heating resistor, 5: Auxiliary conductor, 21: Curved recess.

Claims (1)

[Scope of utility model registration request] 1. A glaze layer is provided on an upper surface of an insulating substrate, a narrow common electrode pattern and an individual electrode pattern are arranged on the glaze layer, and the insulating substrate extends between the common electrode pattern and the individual electrode pattern. Is a thermal head in which parallel heating resistors are provided to the end portions of the common electrodes, and an auxiliary conductor for reducing the common resistance is provided in the narrow common electrode pattern, wherein the glaze layer is a common electrode pattern. In a region where the heat-generating resistor is formed, a part of the side close to the heating resistor is formed in a thin curved shape, and the auxiliary conductor is provided in an upper layer including the thin curved concave portion. .