JP2527007Y2 - Thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head used for a facsimile, a printer, and the like.

[Outline of the invention]

The present invention relates to a thermal head having a glaze layer, a heating element, an electrode, and a protective layer on an insulating substrate, and forming a high thermal conductive layer having electrical insulation before forming the glaze layer on the insulating substrate. The heat radiation characteristics from the layer are improved.

[Conventional technology]

Conventionally, a thin film type thermal head has a glaze layer 2 formed on the surface of an insulating substrate 1 as shown in FIG.
The heating resistor 3 is sputtered thereon to form heating dots. Furthermore, a conductive layer as a pair of electrodes 4 is formed thereon, and the surface is covered with a protective layer 5. Then, by applying a voltage to the electrode 4,
An electric current flows through the heat-generating dots present between the heat-generating dots to generate heat. The heat is transmitted to the heating paper 7 held between the platen 6 and the protective layer 5 via the protective layer 5, and a color is generated. This thermal head is also applied to an ink jet printer and forms a main component of the heat source.

[Problems to be solved by the invention]

Now, assuming printing on thermal paper, the heat generated from the heating dots is transmitted from the dots to the protective layer 5 and transmitted to the thermal paper 7, and the heat transmitted to the insulating substrate 1 in the opposite direction to the thermal paper 7. There is. Generally, in order to efficiently transmit the heat generated from the heating resistor 3 to the thermal paper 7, the insulating substrate 1
The glaze layer 2 is provided on the side. The glaze layer 2 serves as thermal resistance, and the generated heat flows to the thermal paper 7 side. However, when trying to perform high-speed printing, the glaze layer 2 made in consideration of the heat flow does not cool down quickly, causing abnormal heat storage. Would.

Conventionally, in order to eliminate the abnormal heat storage, there has been a method of increasing a heat radiation characteristic by providing a metal layer as a high heat conductive layer on an insulating substrate. However, in this method, when the metal layer is exposed from the glaze layer to improve the heat radiation characteristics, there is a problem in wiring the electrode directly on the glaze layer, and the electrode is formed on the glaze layer avoiding the metal layer. Although a wiring method is conceivable, this method is less practical than a conventional method in which a metal layer is not provided, and the degree of freedom in substrate design is reduced as compared with a method in which wiring is performed over the entire insulating substrate. Furthermore, the fact that the entire surface of the substrate cannot be used for wiring also causes a problem in reducing the size of the thermal head.

In addition, during high-speed printing, a number of pressing impacts between the thermal head and the thermal paper and the impact due to friction during paper feeding are repeated, so a relatively soft material such as metal is placed under the glaze layer. If used, a change in the metal may occur and the glaze layer may be destroyed. For this reason, there has been a problem that the durability and reliability of the thermal head are impaired. Further, there is also a problem that the abnormal heat storage of the glaze layer causes breakage of the heating resistor, the glaze layer, the protective layer, and the electrodes constituting the thermal head when used in an ink jet printer.

[Means for solving the problem]

In order to solve the above-mentioned problem, the present invention provides an electrical insulation between the insulating substrate and the glaze layer as a heat dissipation layer under the glaze layer 2 in order to prevent abnormal heat storage of the glaze layer 2. And a high thermal conductive layer made of a material having a higher thermal conductivity than the glaze layer and the insulating substrate. That is, the manufacturing method is as follows: a high thermal conductive layer made of a material having higher thermal conductivity than the glaze layer or the insulating substrate is formed on the insulating substrate, and the glaze layer is formed thereon by a conventional process, and the heat generation resistance is reduced. The body 3 and the electrode 4 are sequentially patterned, and finally, the protective layer 5 is sputtered to form a thermal head.

[Action]

When printing is performed using the thermal head having the above-described configuration, when printing is performed with one pulse, the glaze layer 2 performs printing as usual with thermal resistance. When performing continuous pulse printing, the high thermal conductive layer 8 assists heat dissipation so that the glaze layer 2 does not abnormally store heat.
Temperature control. As a result, even when high-speed printing is performed, normal printing can be continued without occurrence of printing bleeding, print tailing, and the like.

If the location of the high thermal conductive layer 8 is formed so as to cover not only the lower portion of the glaze layer 2 but also other portions of the insulating substrate 1, the heat stored in the glaze layer 2 can be diffused in the direction of the substrate. The characteristics can be improved. Further, since the electrodes can be arranged directly on the high thermal conductive layer 8, it is possible to contribute to miniaturization.

Further, when applied to an ink jet printer, since abnormal heat storage does not occur, stable printing can be continued without destruction of the thermal head.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, silicon carbide SiC is deposited as a high thermal conductive layer 8 having a thickness of about 10 μm on an insulating substrate 1 made of alumina by sputtering as a high thermal conductive layer 8 which plays a role of heat radiation. The glass paste is printed in a predetermined position thereon, and fired to form a glaze layer 2, it will be deposited by sputtering Ta-SiO ₂ heating resistor 3. Then, one obtained by patterning this into a dot shape by photoetching was prepared. On top of this, Cu was sputtered and exposed using a photomask to pattern the electrode 4. Further, a Ta ₂ O ₅ protective layer 5 was sputtered thereon, and a thermal head of the present invention was prototyped. On alumina insulating substrate 1
In addition, since the SiC high thermal conductive layer 8 having electrical insulation and high thermal conductivity was formed, the electrode 4 was formed on the high thermal conductive layer 8.
Can be installed directly, and the durability increases.

In recent years, thermal heads have been required to be faster and more accurate, and to be smaller. In order to satisfy this requirement, it is also important that the wiring of the electrode 4 can be formed on the high thermal conductive layer 8.

FIG. 3 shows a thermal head (FIG. 2) manufactured by a conventional process.
FIG. 4 shows the result of comparing the printing performance of the thermal head (FIG. 1) of the present invention with that of the present invention. In FIG. 3, the applied voltage 25 W /
Under the condition of mm ² , the pulse width was kept constant at 1 msec, and the pulse cycle was changed to evaluate whether or not print bleeding, print tailing, and the like would occur. FIG. 3 shows the density when continuous printing of all dots is performed. When the density exceeds a certain value (dashed line), it indicates that printing bleeding, print tailing or the like has occurred.
As a result of this comparison, compared to the conventional (dotted line) head,
It can be seen that the head of the present invention (solid line) corresponds to short-period printing, and printing defects such as printing bleeding and printing tailing are less likely to occur.

In this embodiment, the glaze layer 2 is a vitreous layer [thermal conductivity of about 1 W / (m · K)], the insulating substrate 1 is alumina [thermal conductivity of about 20 W / (m · K)], SiC [mostly 100-200 W thermal conductivity]
/ (M · K)] has been described, but the present invention is not limited to this. Any substance having a higher thermal conductivity than the glaze layer 2 and the insulating substrate 1 and having an electrical insulating property may be used. Silicon nitride, diamond, aluminum nitride, and the like can also achieve the object of the present invention.
Also, the printing apparatus using the thermal head of the present invention is not particularly limited. If the printing apparatus utilizes a transient response of heat due to instantaneous heat generation, the head may be destroyed in high-speed printing. It is clear that there is a great effect that stable printing can be obtained without generation.

[Effect of the invention]

As described above, according to the present invention, between the insulating substrate and the glaze layer, a material having electrical insulation properties and good heat dissipation characteristics is used, so that printing quality is secured during high-speed printing, A remarkable effect is obtained, such as miniaturization and high definition, and high durability.

In addition, when the high thermal conductive layer 8 having electrical insulation is used as in the present invention, a relatively low thermal conductivity material such as alumina or glass, which can be easily manufactured and processed, can be used for the insulating substrate. There is also an effect that it is not necessary to select aluminum nitride or the like having a high thermal conductivity until the difficulty in processing is avoided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the thermal head of the present invention, FIG. 2 is a cross-sectional view of the conventional thermal head, and FIG. 3 is a comparison result of the printing performance between the conventional thermal head and the thermal head of the present invention by the pulse period. DESCRIPTION OF SYMBOLS 1 ... Insulating substrate, 2 ... Glaze layer, 3 ... Heating resistor 4 ... Electrode, 5 ... Protective layer, 6 ... Platen 7 ... Thermal paper, 8 ... High thermal conductive layer

Claims (3)

(57) [Scope of request for utility model registration] An at least glaze layer on an insulating substrate,
In a thermal head in which a heating element, an electrode wiring, and a protective layer are sequentially laminated, the thermal head has electrical insulation between the insulating substrate and the grace layer and is larger than the glaze layer and the insulating substrate. A thermal head, wherein a high thermal conductive layer made of a material having thermal conductivity is formed. 2. A high thermal conductive layer is formed on an insulating substrate so as to be exposed from the glaze layer, and electrode wiring is directly formed on at least a part of the high thermal conductive layer at a portion exposed from the glaze layer. The thermal head according to claim 1, wherein the utility model is registered. 3. The thermal head according to claim 1, wherein said high thermal conductive layer is made of a material containing at least one of silicon carbide, silicon nitride, aluminum nitride and diamond.