JPH082657B2 - Thermal head - Google Patents

Description

The present invention relates to a thermal head used for 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 an upper surface of an insulating substrate (alumina ceramic substrate) 1, and common electrode patterns 3 and individual electrode patterns 7 are alternately arranged in sequence on the glaze layer so as to face each other. Common electrode pattern 3
A heating resistor 4 parallel to the end of the insulating substrate 1 is provided over the individual electrode pattern 7 and the substrate 1, the heating resistor 4 and the lead pattern (common electrode pattern 3 / individual electrode pattern 7). The protective film 6 is formed on the surface of the structure.

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-described 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 bulges upwards significantly, and as a result, during printing, the platen roller 9 hits the auxiliary conductor 5 and an appropriate pressure is not applied to the dot portion, resulting in the disadvantage that the printing becomes thin. there were.

Therefore, there has been a demand for a thermal head that achieves downsizing of the head and that does not largely swell the auxiliary conductor portion. As for satisfying this demand, for example, those shown in FIGS. 2 and 3 can be considered.

The second thermal head is a portion where the auxiliary conductor 5 is provided,
That is, this is a system in which the grace layer 2 is not provided from the end of the heating resistor 4 to one end of the insulating substrate 1 (pertaining to a portion not related to heat generation). In the case of this method, the grace layer 2
Auxiliary conductor 5 only for the absence (only for the thickness of the glaze layer)
The height of will definitely be lower. However, since the thermal head is usually subjected to multiple cutting processing (a large number of heads are continuously formed and cut out into a single head after the formation), the end portion of the auxiliary conductor 5 and another adjacent one are formed. Edge part on the opposite side of the head (indicated by arrow A in FIG. 2)
However, if the crack position corresponds to this cutting position (8 cracks) and the crack position shifts, cracks occur at the boundaries of the glaze, and the glaze remains on the head on the B side. There is a disadvantage.

The thermal head shown in FIG. 3 is similar in that the glaze layer 2 is not provided at all in the portion not related to heat generation shown in FIG. 2, but in the multi-grinding process, between the heads formed continuously, that is, This is a system in which a crack 8 device attached to a position corresponding to the auxiliary conductor 5 is provided with a margin to open a certain distance between the heads. In this method, the accuracy of the position where the crack 8 is attached is not so required. But,
The portion without the glaze layer 2 (extra space) is not useless, and it is necessary to form a fine pattern such as the common electrode pattern 3 in this extra space.
The thick film forming method has a disadvantage that the accurate patterning cannot be performed because the paste is accumulated in the extra space.

In the present invention, the above problems are solved, the width of the common electrode pattern is narrow, the heating resistor can be arranged close to the edge of the substrate, the bulge height of the auxiliary conductor is low, and the platen is directly connected to the dot. It is an object of the present invention to provide a thermal head which can be in contact with and can obtain good printing.

(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 is provided in which a heating resistor parallel to an end is provided, and an auxiliary conductor for reducing a common resistance is provided in the narrow common electrode pattern, wherein the glaze layer has a common electrode pattern. It is characterized in that the auxiliary conductor is formed in a region to be formed excluding a part on the side close to the heating resistor, and the auxiliary conductor is provided in an upper layer including the removed part.

In the thermal head having such a configuration, when the auxiliary conductor is provided on the common electrode pattern, the area where the common electrode pattern is formed, and the glaze layer on the side close to the heating resistor is partially removed, A groove-shaped recess is provided. Then, the auxiliary conductor is provided including the groove-shaped recess, that is, the removed portion. Therefore, the auxiliary conductor is formed on the common electrode pattern and over the portion with the glaze layer and the portion without the glaze layer (groove-like recess). The height of the auxiliary conductor is suppressed, and as a result, it can be made approximately the same as the height of the heating resistor. Therefore, as the width of the common electrode pattern is reduced, the heating resistor can be brought closer to the edge of the substrate, and the size can be reduced. In addition, the common resistance can be reduced by the auxiliary conductor, and the printing quality can be made good. By suppressing the bulging height of the auxiliary conductor,
Even if the platen roller is not touched, even dark and light printing can be performed by even pressure. Further, in the multi-chip processing, since the glaze layer is provided and disposed at the cracked portion (the end portion of the substrate) (there is no cutout), the single head can be taken out as usual without any trouble.

(E) Embodiment FIG. 1 is a cross-sectional view of essential parts showing a specific embodiment of the thermal head according to the present invention.

The thermal head of the embodiment has substantially the same head structure as that of the conventional example 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 pattern 3 / individual electrode pattern 7). Further, in order to bring the heating resistor 4 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 as in the conventional example of FIG. An auxiliary conductor 5 that reduces the common resistance 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 is a region in which the common electrode pattern 3 is formed and which is close to the heating resistor 4.
A groove portion 21 is provided by forming a glaze layer 2 with a constant width notch, that is, by removing a constant width length. The auxiliary conductor 5 is provided so as to include the upper surface of the groove-shaped recess 21. Therefore, the auxiliary conductor 5 is on the common electrode pattern 3 and has the lower portion of the glaze layer 2, that is, one end side of the insulating substrate 1 and the lower portion of the glaze layer 2 that is not the groove portion 21 ( It will be formed directly on the insulating substrate 1 and over the part where the part of the common electrode pattern 3 is located). As shown in FIG. 1, a part of the auxiliary conductor 5 falls into the groove-shaped recess 21, so that the auxiliary conductor 5 as a whole.
The height of the heating resistor 4 is suppressed, and as a result, the height of the heating resistor 4 is set to approximately the same level.

In the thermal head having such a configuration, since the width of 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 miniaturization can be achieved. Also, the common resistance can be reduced by the auxiliary conductor 5 provided on the common electrode pattern 3, and the printing quality can be improved. Further, since the auxiliary conductor 5 is provided on the common electrode pattern 3 over the part where the glaze layer 2 is located (on the one end side of the substrate 1) and the part where the glaze layer 2 is not located (the groove-shaped recess 21), The bulging height of the auxiliary conductor 5 is suppressed by the amount that the auxiliary conductor 5 bulges into the groove-shaped recess 21. Therefore, at the time of printing, the auxiliary conductor 5 does not hit the platen roller 9, and uniform dark and light printing can be performed by uniform pressing. Further, in the multi-chip processing, a portion to be cracked (the end portion of the substrate 1)
Since the glaze layer 2 is disposed on the substrate (since it is not cut), the single head can be taken out as usual without any trouble.

(F) Effect of the Invention According to the present invention, 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. It was formed by removing a part on the side close to the resistor, and the auxiliary conductor was provided on the upper layer including this removed part. , Can be brought closer to each other, and miniaturization can be achieved. 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, the auxiliary conductor is on the common electrode pattern and has a glaze layer at the bottom (one side of the substrate).
Since it is provided over the non-existing portion (groove-shaped recess), the bulging height of the auxiliary conductor is suppressed by the amount of the recessed portion. Therefore, at the time of printing, the auxiliary conductor does not hit the platen roller, and uniform dark and light printing can be performed by uniform pressing. Further, in the multi-chip processing, since the glaze layer is provided and disposed at the cracked portion (the end portion of the substrate) (since it is not cut), there is no obstacle to take out the single head. It has the excellent effect of achieving the purpose.

[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 a sectional view showing a main part of a recently proposed thermal head, FIG. 3 is a sectional view showing a main part of a recently proposed thermal head, and FIG. 4 is a conventional thermal head. FIG. 5 is a plan view of a main part, and FIG. 5 is a cross-sectional view of the main part showing another conventional thermal head. 1: Insulating substrate, 2: Glaze layer, 3: Common electrode pattern, 4: Heating resistor, 5: Auxiliary conductor, 21: Groove-shaped recess.

Claims (1)

[Claims] 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 is provided 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 the region formed in, except for a part of the side close to the heating resistor,
A thermal head comprising the auxiliary conductor provided on an upper layer including the removed portion.