JP2000225722A - Thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance not only the print quality but also the print efficiency through the profile of a projecting glaze by providing a flat part parallel with the plane of an insulating substrate at the top of the projecting glaze and forming a heating element at the flat part thereby suppressing microscopic fluctuation of density. SOLUTION: A projecting glaze 16 is formed on the surface of an insulating substrate 1 and a flat part 17 parallel with the plane of the insulating substrate 1 is formed in the vicinity of the top of the projecting glaze 16. The flat part 17 has a length Lg1 in the direction of short side being a length 18 of the flat part and a heating element 4 is formed on the surface of the flat part 17 of the projecting glaze 16. Electrodes 5 are provided to cover the opposite ends of the heating element 4 and a protective layer 6 is formed on the surface thereof. A relationship Lg1>=Lq1 is satisfied between the length Lq1 of the heating part of the heating element 4 and the length Lg1 of the flat part. According to the structure, thermal energy is concentrated only to a local part at the flat part 17 of the projecting glaze 16 during conduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a structure of a thermal type thermal head mounted on a facsimile, a printer or the like.

[0002]

2. Description of the Related Art In recent years, a thermal type thermal head mounted on a facsimile, a printer, or the like has been required to have high printing efficiency in accordance with a demand for low power consumption of a mounted device. As means for realizing this low power consumption, a convex glaze mainly composed of silicon dioxide is formed on a substrate, and the heat generated by a heating resistor formed near the apex of the convex glaze is generated. The system prints on thermal paper.

FIG. 1 is a view showing the structure of a conventional thermal head. FIG. 1 is a cross-sectional view in the short side direction of a conventional thermal head, in which a glaze layer 2 formed on an insulating substrate 1 has a convex portion 3 having a locally curved shape. Generally, a glaze having such a structure is called a convex glaze or simply a convex glaze. A heating resistor 4 is formed near the apex of the projection 3, and an electrode 5 for supplying a current to the heating resistor 4 to generate heat is electrically connected to the heating resistor 4. Heating resistor 4
A protective film 6 is formed to prevent the electrodes 5 from directly contacting the thermal paper 7 transported by the roll 8. At this time, the presence of the convex portion 3 causes the thermal paper 7 to come into strong contact with the protective film 6, and as a result, the heat generated from the heating resistor 4 can efficiently color the thermal paper 7. . As described above, the use of the convex glaze has a feature that the thermal paper can be efficiently colored even in a low voltage state.

FIG. 2 is a perspective view of the thermal type thermal head shown in FIG. 1, in which a protective film, a thermal paper, and a roll are omitted for simplicity. Normally, the thermal head has a rectangular shape as shown in FIG. 2, and the projections 3 formed on the insulating substrate 1 also have a rectangular shape according to the shape of the thermal head. A plurality of heating resistors 4 and electrodes 5 are arranged near the apex of the glaze projection 3. At this time, the wiring direction of the electrode 5, that is, the energization direction is the same as the short side direction of the rectangular shape.

Next, FIG. 3 is an enlarged view of a heating resistor and an electrode for energization. The heating resistor 4 is formed in the vicinity of the convex portion 3, and the length Lr of the heating resistor is equal to the heating resistor length 9.
It is. An electrode 5 is provided so as to cover a part of both ends of the heating resistor 4.
Are formed. At this time, when a current is applied to the heating resistor 4 by the electrode 5, only the portion having the length Lq in the drawing generates heat. This length Lq is the heating part length 10.

[0006]

As described above, FIGS.
Since the apex of the convex glaze is a curved line, the thermal paper tends to contact the heating resistor only at one point.
Therefore, the print density is locally divided into a dark portion and a light portion of the print, and there is a microscopic unevenness in the print density. There is a problem that this microscopic unevenness in print density leads to macroscopic deterioration of print quality.

This problem will be described in detail with reference to FIG. FIG. 4 is a schematic diagram showing a state where the printing pressure in the vicinity of the apex of the convex portion 3 shown in FIGS. 1 to 3 is dispersed.
It goes without saying that the printing pressure applied to the entire thermal head is applied intensively to the thermal paper due to the projection effect of the convex glaze. Because of the curved shape, f1
As in the case of f3, the concentration is dispersed. In FIG. 4, the pressure f2 at the top is directly
And f1 and f3 act on the thermal paper 7 at a certain distance 11 on the thermal paper. In this case, the printing at the portion where the pressure f2 acts is dark, and f1, f
There occurs a phenomenon that the film becomes relatively thin in a portion where 3 acts. This phenomenon is a major cause of deterioration in print quality. Further, even if the center of the heating resistor is slightly deviated from the apex position, it is impossible to directly act on the thermal paper directly, resulting in blurring of the print. Further, there is a problem that the printing efficiency is not improved as expected because of such microscopic print density unevenness.

The problem of the printing efficiency has become a very serious problem in a low-voltage-driven thermal head of a driving voltage of 5 V or less recently required by the market. Also,
The problem of print quality is a major problem in a thermal type thermal head for color printing.

[0009]

In order to solve the above problems, a flat portion parallel to the insulating substrate is provided near the top of the convex glaze.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. In FIG. 5, the insulating substrate, the electrodes, the heating resistor, the protective film, and the roll are omitted for simplicity. As shown, the vicinity of the vertex of the convex glaze 12 is not a curve but a flat shape. The flat portion is the flat portion 13 in the drawing, and the insulating substrate and the flat portion 13 are parallel. The vicinity of the vertex is a flat portion, and the flat portion 13
Are parallel to the insulating substrate, the printing pressure does not cause a dispersion phenomenon near the peak as shown in FIG. Therefore, all of the concentration forces f1 to f3 are generated from the flat portion 13 in the vertical direction. In this case, the distance 14 when the concentration forces f1 and f3 act on the thermal paper 7 is shorter than the distance 11 in FIG.

As a result, the microscopic density unevenness described above is reduced, and not only the printing quality is improved, but also the printing efficiency due to the convex glaze shape is greatly improved. Further, since the flat portion 13 exists, even if the center position of the heat generating resistor slightly shifts, not only there is a point which directly acts on the thermal paper, but also the distance 14 in the drawing does not change, so that printing blur is caused. There is also an effect that no occurrence occurs.

[0012]

FIG. 6 is a view showing a cross section in the short side direction of an embodiment of the thermal head according to the present invention. A convex glaze 16 is formed on the surface of the insulating substrate 1, and a flat portion 17 parallel to the surface of the insulating substrate 1 is formed near the vertex of the convex glaze 16. The length Lg1 of the flat portion 17 in the short side direction is the flat portion length 18. The heating resistor 4 is formed on the surface of the flat part 17 having such a convex glaze. An electrode 5 is formed so as to cover both ends of the heating resistor 4, and a protective film 6 for protecting both electrodes is formed on the surface. Here, in the heating resistor 4, the heating portion length 19 is Lq1, and this Lq1 and the flat portion length Lg
1 satisfies the following relational expression (1).

Lg1> = Lq1 Equation (1) By satisfying the relational equation (1), heat generated at the time of energization is limited to a more localized portion of the flat portion 17 of the convex glaze 16 where heat energy is generated. Will be concentrated.
Therefore, it is possible to realize a thermal type thermal head having extremely high printing efficiency, which has not been achieved in the past, without deteriorating the printing quality.

In FIG. 6, both ends of the heating resistor 4 overlap the electrodes 5. This overlapping portion does not affect the heat generation at the time of energization. Therefore, the magnitude relationship between the dimensions of both ends of the heating resistor 4 and the flat portion length 18 is merely a design matter and is not shown in the drawings. Even if the length of both ends of the heating resistor 4 is larger than the length Lg1 of the flat portion length 18, there is no problem and the effect is not changed.

FIG. 7 shows another embodiment according to the present invention.
As in FIG. 6, it is composed of an insulating substrate 1, a convex glaze 20, a flat portion 21, a heating resistor 4, an electrode 5, and a protective film 6. In the drawing, a flat portion length 22 has a dimension value Lg2. Further, the length of the heating resistor 4 is formed to be longer than the flat portion length 22, and satisfies the following relational expression (2) as compared with the dimension value Lq 2 of the heating portion length 23.

Lq2> Lg2 Equation (2) By satisfying the relational equation (2), heat energy can be uniformly distributed on the surface of the flat portion 21, and extremely high printing can be performed without deteriorating printing efficiency. A high quality thermal head can be realized.

[0017]

According to the present invention, the thermal type thermal head having a flat portion near the apex of the convex glaze can realize high printing quality and high printing efficiency by the above-described operation. In particular, by arranging the heat generating portion near the flat portion of the convex glaze according to the relational expression (1), it is possible to realize a very large improvement in printing efficiency while maintaining the same printing quality as that of the related art. It has become. In particular, the effect can be remarkably exerted in a low-voltage drive type thermal head in which the drive voltage is 5 V or less, particularly about 3 V.

Further, since the heat energy can be distributed on average by the relational expression (2), it is possible to prevent print blurring or the like due to print density unevenness, displacement of the center of the heat resistor, and the like. Therefore, the present invention has a great effect that a very high printing quality can be realized, which cannot be realized by the conventional convex glaze, and has a great effect in a thermal printer requiring color printing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in the short side direction of a conventional thermal head.

FIG. 2 is a perspective view of a conventional thermal head.

FIG. 3 is an enlarged view of a conventional heating resistor section.

FIG. 4 is a conceptual diagram showing a printing pressure distribution in the vicinity of a conventional convex glaze vertex.

FIG. 5 is a conceptual diagram for explaining the function of convex glaze according to the present invention.

FIG. 6 is an enlarged view of a heating resistor portion of the thermal head according to the present invention.

FIG. 7 is an enlarged view of a heating resistor portion of a thermal head according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 4 Heating resistor 5 Electrode 6 Protective film 16, 20 Convex glaze 17, 21 Flat part 18, 22 Flat part length 19, 23 Heating part length

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[Procedure amendment]

[Submission date] March 13, 2000 (200.3.1)
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

Next, FIG. 3 is an enlarged view of a heating resistor and an electrode for energization. The heating resistor 4 is formed near the apex of the convex portion 3 , and the length Lr of the heating resistor is the heating resistor length 9. An electrode 5 is formed so as to cover a part of both ends of the heating resistor 4. At this time, when a current is applied to the heating resistor 4 by the electrode 5, only the portion having the length Lq in the drawing generates heat. This length Lq is the heating part length 1
0.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007] will be described in detail have use 4 this problem. FIG. 4 is a schematic diagram showing a state where the printing pressure in the vicinity of the apex of the convex portion 3 shown in FIGS. 1 to 3 is dispersed.
It goes without saying that the printing pressure applied to the entire thermal head is applied intensively to the thermal paper due to the projection effect of the convex glaze. Because of the curved shape, f1
As in the case of f3, the concentration is dispersed. In FIG. 4, the pressure f2 at the top is directly
And f1 and f3 act on the thermal paper 7 at a certain distance 11 on the thermal paper. In this case, the printing at the portion where the pressure f2 acts is dark, and f1, f
There occurs a phenomenon that the film becomes relatively thin in a portion where 3 acts. This phenomenon is a major cause of deterioration in print quality. Further, even if the center of the heating resistor is slightly deviated from the apex position, it is not possible to directly act on the thermal paper directly, resulting in blurring of printing or the like. Further, there is a problem that the printing efficiency is not improved as expected because of such microscopic print density unevenness.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

The thermal type thermal head having a flat portion near the apex of the convex glaze according to the present invention can achieve high printing quality and high printing efficiency by the action described above. In particular, by obtained by localized heating portion in the vicinity of the flat portion of the convex glaze by equation (1), improvement of very large printing efficiency while maintaining the print quality of the conventional level can be achieved structure It has become. In particular, the driving voltage that is especially about 3V or less 5V, the heat-sensitive thermal head for low voltage drive is also to exert significant effect.

Claims (3)

[Claims] 1. A convex glaze layer formed on an insulating substrate, a heating resistor and a current application electrode pattern formed near a vertex of the convex glaze layer, and protection for protecting the heating resistor. A thermal head, wherein a top portion of the convex glaze has a flat portion parallel to a surface of the insulating substrate, and the heating resistor is formed on the flat portion. . 2. A heating device according to claim 1, wherein a length of the heating portion of the heating resistor is smaller than a short side dimension of the flat portion.
The thermal head according to 1. 3. The thermal head according to claim 1, wherein the short side dimension Lg of the flat portion and the length Lq of the heat generating portion of the heat generating resistor satisfy a relationship of Lg <Lq.