JPH03247467A - Thermal head - Google Patents

Abstract

PURPOSE:To achieve satisfactory thermal conductivity with a heating element formed in smooth convex by forming a thermal head in a structure wherein a feeding body end nonconductive body are formed over a heat insulating layer and a heating resistive body is provided over the nonconductive body. CONSTITUTION:A heat insulating layer 2 made of glazed glass or the like is formed over an insulating aluminum substrate 1, and feeding bodies 3a, 3b are formed over the heat insulating layer 2 and a nonconductive body 4 is provided in the same layer as that for the feeding bodies 3a, 3b. Furthermore, a heating resistive body layer 5 made of Ta2N or the like formed by sputter method is laid over the feeding bodies 3a, 3b and the nonconductive body 4, and a protection layer 6 made of SiO2 or the like formed by the sputter method or the like is provided over the heating resistive body layer 5. With the above- mentioned structure, a thermal head in inverted circular-arc section in smooth convex can be obtained. By providing the nonconductive body 4 to a position on the top of the convex sectional shape, a heating element becomes able to make contact directly with printing face, and thereby satisfactory heat conductivity can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head incorporated in a thermal printing device or the like.

[Prior Art] It has been desired to improve the printing performance of thermal heads. Since such characteristics are greatly influenced by the thermal conductivity from the thermal head to the printing surface of thermal recording paper or the like, various improvements in this regard have been proposed.

FIG. 2 is a configuration diagram schematically showing a cross section of a conventional thermal head. As shown in FIG. 2, in the conventional thermal head, a heat insulating layer 12 is placed on an insulating substrate 11.
is provided, on which a heating resistor layer 13 and a power supply body 14a are provided.
14b1, an anti-oxidation layer 15, and a protective layer 16 are provided in this order. Then, the power supply bodies 14a and 14 of the heating resistor 13
The part A between it and b becomes a heat generating part. In the conventional thermal head described above, since the upper part of the heat generating part A is the recessed part B, a gap is created between the heat generating part A and the printing surface during printing. An air layer exists in the gap formed by the recess B, and the heat generated in the heat generating portion A is transmitted to the printing surface via the air layer, so that the thermal conductivity is extremely poor.

JP-A-61-74860 discloses a thermal head in which a metal layer having the same shape as the heating resistor is provided on the heating resistor in order to improve the thermal conductivity to the printed surface. . FIG. 3 is a configuration diagram schematically showing a cross section of the thermal head disclosed in the above publication. Third
In the figure, the same components as in FIG. 2 are denoted by the same reference numerals, and their explanation will be omitted.

As shown in FIG. 3, the thermal head disclosed in the above publication is provided with a metal layer 17 having the same shape as the heat generating part A on a portion of the anti-oxidation layer 15 facing the heat generating part A. A protective layer 16 is provided on the metal layer 17 to cover the entire thermal head. The thermal head has a protrusion C formed by the metal layer 17.

Since the thermal head disclosed in the above publication has the above-described structure, during printing, the protrusion C directly contacts the printing surface, with an air layer interposed between it and the printing surface. Never. Therefore, in the above thermal head, the heat generating part A
The heat generated in is efficiently transmitted to the printing surface.

According to the description in the above-mentioned publication, the metal layer 17 is formed by forming a first metal layer of a material such as aluminum by thin film technology at a position facing the heat generating part A on the anti-oxidation layer 15, and then forming the first metal layer using a material such as aluminum. It is said that it can be manufactured by forming a second metal layer of a material such as nickel on the metal layer using a technique such as electroless plating.

[Problems to be Solved by the Invention] However, in the thermal head disclosed in the above-mentioned publication, it is difficult to form the metal layer formed at the position facing the heat generating part into an appropriate shape, resulting in a decrease in printing quality. There is a problem that sometimes happens.

That is, when the metal layer formed above is thicker than the heat generating part, a part of the metal layer will be formed on the power supply body, and a gap will likely occur between the metal layer and the power supply body. , heat from the heat generating part tends to be transferred unevenly,
Moreover, the printed dot becomes larger than a predetermined size. Further, when the formed metal layer is smaller than the heat generating portion, the printed dots become smaller than a predetermined size.

Therefore, the present invention has been made to solve the problems of the prior art as described above, and its purpose is to:
It is an object of the present invention to provide a thermal head that has good thermal conductivity to a printing surface and can obtain printing dots of appropriate size.

[Means for Solving the Problems] A thermal head according to the present invention includes an insulating substrate, a heat insulating layer provided on the insulating substrate, a power supply body provided on the heat insulating layer, and the same as the power supply body. It is characterized by having a non-conductor provided in one layer, and a heating resistor provided on the power supply body and the non-conductor.

[Function] In a thermal head, heat is usually generated by applying a voltage between a power supply and a common electrode.

The thermal head of the present invention has a structure in which a power supply body and a nonconductor are provided on a heat insulating layer, and a heating resistor is provided on the power supply body and the nonconductor. Therefore, the current due to the voltage application flows toward the power supply body in the part where the power supply body is provided because the electric resistance of the power supply body is smaller than that of the heat generating resistor, and the heat generating resistor on the power supply body is substantially Does not generate heat. On the other hand, in a portion provided with a non-conductor, the current flows to a heat-generating resistor on the non-conductor, so that the heat-generating resistor generates heat.

Therefore, in the thermal head of the present invention, the portion of the heat generating resistor located on the upper surface of the non-conductor is selectively made to generate heat and becomes a heat generating portion.

Further, since the thermal head of the present invention has the above-described structure, the heat generating portion has a smooth convex shape, and heat transfer is improved.

[Example code] The present invention will be explained below based on illustrated embodiments.

FIG. 1 is a schematic diagram showing an embodiment of a thermal head according to the present invention. To explain the configuration of this embodiment based on the figure, in this embodiment, a heat insulating layer 2 made of glazed glass or the like is provided on an insulating alumina substrate 1, and a power supply unit is placed on this heat insulating layer 2. 3a and 3b are provided, and a nonconductor 4 is provided in the same layer as the power feeders 3a and 3b. Then, on the power supply bodies 3a, 3b and the nonconductor 4, a heating resistor layer 5 made of T a 2 N or the like is formed by sputtering, and a heating resistor layer 5 is formed by sputtering on the heating resistor layer 5. SiO formed by etc.
A protective layer 6 made of 2 etc. is provided.

With the above configuration, a thermal head having a smooth convex inverted arcuate cross-sectional shape can be obtained.

In this embodiment, the power supply bodies 3a, 3b and the nonconductor 4 are formed as follows. First, an aluminum layer is formed on the heat insulating layer 2 by sputtering or the like. Next, the aluminum layer is coated with a resist pattern formed by applying a photoresist and exposing and developing the pattern using a glass mask or the like, and then the exposed portions are treated to become non-conductive.

The above-mentioned passivation treatment is performed by selectively alumiteizing the above-mentioned aluminum layer. The selective alumite formation can be carried out by a method known per se, such as by immersing the aluminum layer in an oxalic acid solution using the resist pattern described above as a mask. As a result of the alumite treatment, the portions remaining without being alumitized become the power feeders 3a, 3b, and the alumite portions become the nonconductor 4.

In this embodiment, the nonconductor 4 is preferably provided at the top of the convex cross-sectional shape. By providing the nonconductor 4 in the above portion, the heat generating portion comes into direct contact with the printing surface during printing, so that good thermal conductivity can be obtained.

In a thermal head, a plurality of heat generating parts are generally provided on a substrate. In this case, it is necessary that the power feeder of the negative heat generating part be an individual electrode that is electrically insulated from the power feeders of the other adjacent heat generating parts.

In this embodiment, as shown in FIG. 4, since the portion 5a forming the nonconductor 4 and the insulating part 5b between the power feeders are simultaneously made into a nonconductor during the above-mentioned passivation process, each individual A power supply body (individual electrode) 7 that is insulated can be formed. One of the individual electrodes 7 (either one of the power supply bodies 3a or 3b in FIG. 1) is connected to the common electrode portion 8.

Further, the thermal head further includes an alumina substrate 1
It may also be a structure in which an insulating layer is provided between the heat insulating layer 2, the power supply bodies 3a, 3b, and the nonconductor 4, or a structure in which a stress relaxation layer is provided on the heat insulating layer 2. There may be.

[Effects of the Invention] As explained in detail above, according to the present invention, it is possible to manufacture a thermal head having a convex cross section, and by providing a non-conducting portion at the top of the convex cross section, the heating resistor A portion provided on the non-conducting portion of the body can be selectively used as a heat generating portion.

In the thermal head, the top portion of the convex cross section becomes a heat generating portion and directly contacts the printing surface, so that good thermal conductivity to the printing surface can be obtained.

Further, the nonconductor portion is formed by covering a part of the metal layer formed as a power supply body with a mask pattern, and making the exposed portion not covered by the mask pattern nonconductive. Therefore, the nonconductor portion can be formed into any shape and size by the mask pattern,
Printed dots of appropriate shape and size can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a thermal head according to the present invention, FIG. 2 is a schematic configuration diagram showing a conventional example of a thermal head, and FIG. 61-7
FIG. 4 is a plan view showing a part of an aluminum layer provided with a plurality of heat generating parts by passivation treatment. 1.11...Alumina substrate, 2.12...Heat insulation layer, 3a, 3b, 14a, 14b-...Power supply body, 4...
- Nonconductor, 5.13... Heat generating resistor, A... Heat generating part.

Claims (1)

[Scope of Claims] An insulating substrate, a heat insulating layer provided on the insulating substrate, a power supply body provided on the heat insulating layer, a non-conductor provided in the same layer as the power supply body, and the power supply body. What is claimed is: 1. A thermal head comprising: a heating resistor provided on a nonconductor;