JPH0890809A - Thermal head and manufacture thereof - Google Patents

Abstract

PURPOSE: To enhance the wear resistance and the thermal response of a thermal head by forming a protective film of a wear resistant layer provided on an oxidation resistant layer and a sacrificial wear layer containing the same material as that of the oxidation resistant layer provided on the wear resistant layer as a main ingredient. CONSTITUTION: When a thermal recording sheet is printed by using a thermal head, the Si-Al-O-N material as a sacrificial wear layer 8 formed on the uppermost part is first worn. Thus, the upper surface of a protective layer 7 of the individual electrode side on a heat generator 3 which receives a local pressure is so worn to be deformed in the shape as to be brought into contact with the entire sheet. When the layer 8 is worn and the wear resistant layer 6 is exposed, the local stress to be applied to the layer 4 can be alleviated, and the stress can be sufficiently absorbed by the layer 6 itself. Even if the thickness of the layer 7 of the head is thinned by about 2μm as compared with prior art, an initial fracture such as crack, peeling, etc., does not occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used in a thermal printer and a method of manufacturing the same, and more particularly to improvement of a protective layer thereof.

[0002]

2. Description of the Related Art Generally, a thermal head used in a thermal printer has, for example, a plurality of heating elements arranged linearly on an insulating substrate 1 and selectively heats the heating elements by energizing them according to recorded information. Then, the thermal recording paper is used for color recording, or the ink of the ink ribbon is melted and transferred / recorded on plain paper.

FIG. 5 shows a sectional structure of a general thermal head. As shown in the figure, a glaze layer 2 made of glass that functions as a heat insulating layer is formed on the surface of an insulating substrate 1 made of Al ₂ O ₃ or the like, and the upper surface of the glaze layer 2 is heated by Ta ₂ N or the like. The element 3 is formed into a film by sputtering or vapor deposition, and then patterned by etching.

A common electrode 4a for supplying power to each heating element 3 is formed on both upper surfaces of the patterned heating element 3.
And individual electrodes 4b are formed respectively. Each of these electrodes 4 is made of, for example, a metal such as Al, Cu, Au, etc., is formed into a film by sputtering or vapor deposition, and is then patterned by etching.

A protective layer 7 having a thickness of about 7 to 10 μm is formed on the glaze layer 2, the heating element 3 and the electrode 4 to protect the heating element 3 and the electrode 4. The protective layer 7 includes an oxidation resistant layer 5 having a thick film of about 2 μm made of SiO ₂ or the like for protecting the heat generating element 3 from deterioration due to oxidation, and abrasion due to contact with an ink ribbon or the like laminated on the oxidation resistant layer 5. The heat-generating element 3 and the electrode 4 are formed of a wear-resistant layer 6 of Ta ₂ O ₅ or the like having a film thickness of approximately ₅ to 8 μm.

However, Ta ₂ O is added to the wear resistant layer 6 as described above.
_In the thermal head composed of ₅ series materials,
The abrasion resistance is not sufficient and, for example, in the case of printing on a thermal recording paper without using an ink ribbon, the abrasion resistant layer 6 of the thermal head is significantly worn due to the influence of the coat layer on the surface of the thermal recording paper, resulting in an extremely long life. There is a problem that it becomes short.

In order to solve this problem, the wear resistant layer 6
Superior (hereinafter abbreviated as CrONY) Cr-Y-O- N system has been developed which use, 4 [mu] m of membrane CRONY as wear-resistant layer 6 of the material as a T ₂ aO-material than the wear resistance of such ₅ The thickness of the oxidation resistant layer 5 is 3 μm of SiO ₂ based material.
Sufficient reliability is obtained by setting the film thickness to m.

[0008]

On the other hand, recent thermal printers are required to have high printing speed and high printing quality. For this purpose, it is necessary to improve the thermal response of the thermal head. Therefore, the thickness of the protective layer 7 must be made as thin as possible.

[0009] Here, the protective layer 7 while maintaining wear resistance.
In order to reduce the thickness, it is conceivable to reduce the thickness of the oxidation resistant layer 5 without changing the thickness of the wear resistant layer 6. For example,
If the oxidation resistant layer 5 is set to 1 μm and the wear resistant layer made of CrONY is formed on the upper surface to a thickness of 4 μm, a thermal head having sufficient wear resistance can be obtained even if the thickness of the protective layer 7 is reduced. Expected to be However, as a result of making a thermal head having such a structure and conducting a test, it was found that cracks, peeling, etc. occurred in the protective layer 7 in a short time and the heating element 3 was oxidized very early. The cause of this early destruction is that CrONY as a wear-resistant layer is a brittle material that is not easily elastically deformed. Therefore, the local stress generated by the sliding of the thermal recording paper and the thermal head causes internal stress in the protective layer 7. It is thought to be due to the inability to be absorbed by. That is, it is considered that the oxidation resistant layer 5 formed to have a film thickness of 3 μm described above has a function of relieving stress in addition to the function of preventing oxidation.

The present invention has been made to solve the above-mentioned problems, and while maintaining sufficient wear resistance,
It is intended to provide a thermal head having high thermal response.

[0011]

In order to achieve the above object, the thermal head according to the present invention according to claim 1 is a heat insulating layer formed on the surface of a substrate, and a plurality of heat insulating layers formed on this heat insulating layer. A heat-generating element, individual electrodes and a common electrode for supplying electric power to each of these heat-generating elements, the heat-retaining layer, each heat-generating element and a protective layer laminated on each electrode, The layer is composed of an oxidation resistant layer, a wear resistant layer laminated on the oxidation resistant layer, and a sacrificial wear layer laminated on the wear resistant layer and containing the same material as the oxidation resistant layer as a main component. Is characterized by.

Further, in the thermal head of the present invention according to a second aspect, a heat retaining layer formed on the surface of the substrate, a plurality of heat generating elements formed on this heat retaining layer, and power to each of these heat generating elements is provided. A thermal head having an individual electrode and a common electrode for supplying heat, a heat insulating layer, a heating element, and a protective layer laminated on each electrode, wherein the protective layer is alternated with an oxidation resistant layer and an abrasion resistant layer. It is characterized in that it is formed by laminating a plurality of times.

According to a third aspect of the thermal head of the present invention, a heat retaining layer formed on the surface of the substrate, a plurality of heat generating elements formed on the heat retaining layer, and each of these heat generating elements are supplied with power. A thermal head having an individual electrode and a common electrode for supplying the heat insulating layer, the heat retaining layer, each heating element and a protective layer laminated on each electrode, wherein the protective layer includes a lowermost oxidation resistant layer and an uppermost layer. Of the wear-resistant layer and the oxidation-resistant layer and the wear-resistant layer formed of the same material as the oxidation-resistant layer and the wear-resistant layer. It is characterized in that it is constituted by an intermediate layer formed by alternately laminating coating layers a plurality of times.

According to a fourth aspect of the present invention, there is provided the thermal head according to any one of the first to third aspects, wherein the wear resistant layer is at least one of Cr, Ti, B, Zr and Y. It is characterized in that it is composed of a nitride or oxide of one kind of metal or a mixture of at least one of these nitrides and oxides.

A thermal head according to a fifth aspect of the present invention is the thermal head according to any one of the first to third aspects, wherein the oxidation resistant layer is a nitride of at least one metal of Si and Al, or It is characterized by being composed of an oxide or a mixture of at least one of these nitrides and oxides.

A thermal head manufacturing method according to a sixth aspect of the present invention is the method of manufacturing a thermal head according to any one of the first to third aspects, wherein the oxidation resistant layer is 2 to 15% O in Ar gas.
_The feature is that the film is formed by adding _two gases.

[0017]

According to the thermal head of the present invention having the above-mentioned constitution, when printing on the thermal recording paper, the film as the sacrificial wear layer formed on the uppermost layer is worn at the initial stage, which causes local damage. The upper surface of the protective layer on the side of the individual electrode on the heating element which has been subjected to the pressure is worn and deformed into a shape such that the entire surface of the protective layer comes into contact with the thermal recording paper. Thereby, when the coating is further worn and the abrasion resistant layer is exposed, the local stress applied to the abrasion resistant layer can be relaxed, and the abrasion resistant layer itself can sufficiently absorb the stress.

When the protective layer is a thermal head in which an oxidation resistant layer and a wear resistant layer are alternately laminated a plurality of times,
The stress generated by sliding of the thermal head on the thermal recording paper is absorbed by the oxidation resistant layer sandwiched by the wear resistant layer, and initial damage such as cracking or peeling does not occur. Even if the abrasion-resistant layer is peeled off, the laminated layers are peeled off one by one, so that the entire protective layer is rarely cracked or peeled off. Furthermore, the oxidation resistant layer is used as Ar gas.
Since the film is formed by adding O ₂ gas of ˜15%, the oxidation resistant layer has high toughness, and the thermal head can extend its life without causing initial damage.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. It should be noted that the same components as those of the conventional one described above are denoted by the same reference numerals in the drawings, and description thereof is omitted.

2 to 4 corresponding to the description of the second to fourth embodiments to be described later, the sectional shape of the heat retaining layer 2 is drawn in a plane shape for the convenience of drawing. As shown in FIG. 1, is formed in a shape having a convex portion in the central portion.

FIG. 1 shows a first embodiment of the present invention, in which a heat insulating layer 2 is formed on the surface of an insulating substrate 1 made of Al ₂ O ₃ or the like.
A glaze layer 2 functioning as is formed, a heating element 3 made of Ta ₂ N or the like is formed on the upper surface of the glaze layer 2 by sputtering or vapor deposition, and then patterned by etching. On each upper surface of both sides of the patterned heating element 3, each heating element 3 is formed.
A common electrode 4a and an individual electrode 4b for supplying power to the respective electrodes are formed.

On the upper surfaces of the heating element 3 and the electrode 4, an oxidation resistant layer 5 made of a Si--Al--O--N (hereinafter abbreviated as SiAlON) -based material is formed so as to cover them.
1 μm, a wear-resistant layer 6 made of a CrONY-based material is 3 μm thereon, and a sacrificial wear layer 8 made of SiAlON is further laminated in order of 1 μm to form the protective layer 7 as a whole.

According to the thermal head of the first embodiment as described above, when printing on the thermal recording paper, first, the SiAlON as the sacrificial wear layer 8 formed on the uppermost layer is abraded, thereby locally Heating element 3 that received a great pressure
The upper surface of the protective layer 7 on the upper side of the individual electrode is worn and deformed into a shape such that the upper surface of the protective layer 7 is entirely in contact with the thermal recording paper. When the sacrificial wear layer 8 is abraded and the wear resistant layer 6 is exposed, local stress applied to the wear resistant layer 6 can be relaxed, and the wear resistant layer 6 can be relaxed.
The stress itself can be sufficiently absorbed.

According to the thermal head of the first embodiment described above, the thickness of the protective layer 7 is about 5 μm, which is about 2 μm thinner than that of the conventional protective layer 7. As a result of the durability test, it was found that practically sufficient durability was obtained without causing initial fracture such as cracking or peeling.

Therefore, the thermal response of the thermal head during printing can be improved, and the printing speed and printing quality can be improved.

The structure of the thermal head according to the first embodiment and the structure of the thermal head according to the other embodiments described below are the same except for the structure related to the protective layer 7. Will not be described.

Next, a second embodiment of the present invention is shown in FIG. The protective layer 7 in the second embodiment is configured such that an oxidation resistant layer 5 made of SiAlON and having a thickness of 0.2 μm and a wear resistant layer 6 made of CrONY and having a thickness of 0.8 μm are alternately laminated five times in total. Has become. That is, the protective layer 7 is formed by laminating a total of 10 layers.

According to the thermal head having the protective layer 7 having such a structure, the stress generated by sliding on the thermal recording paper is absorbed by the oxidation resistant layer 5 sandwiched between the abrasion resistant layers 6. It suppresses the occurrence of cracks, peeling and the like. Also,
Even if the abrasion resistant layer 6 peels off,
Since only the layers are peeled off, the protection layer 7 as a whole can be prevented from cracking and peeling.

Further, the protective layer 7 has a thickness of 5 μm, which is 2 μm thinner than the conventional example described above.
As a result of the endurance test, as in the case of the first embodiment described above, initial damage such as cracking and peeling did not occur, and practically sufficient durability was obtained.

Therefore, the thermal response of the thermal head at the time of printing can be improved, and the printing speed and high printing quality can be secured.

Next, FIG. 3 shows a third embodiment of the present invention. The protective layer 7 in the present embodiment is formed by forming SiAlON as the oxidation resistant layer 5 to a thickness of 1 μm on the heating element 3 and then forming a wear resistant layer 6 made of Cr-ON (hereinafter abbreviated as CrON) on the upper surface thereof. Of 0.8 μm and SiAlON of 0.2 μm as a stress relaxation layer and CrON of 0.8 μm as a wear resistant layer 6 are alternately laminated on the upper surface three times in total. .

The thickness of the protective layer 7 of the third embodiment thus constituted is 4.8 μm, which is thinner than the above-mentioned conventional example by about 2 μm or more. As a result of performing a durability test using the thermal head of the third embodiment having such a configuration, as in the case of the above-described embodiments, initial damage such as cracking and peeling did not occur, and practically sufficient durability was obtained. Was obtained. Further, even if the uppermost CrON film is partly peeled off, the heating element 3 is not affected and good printing can be performed.

Further, in the conventional thermal head in which the abrasion resistant layer 6 has a thickness of 3 μm and the oxidation resistant layer 5 has a thickness of 2 μm, the protective layer 7 is cracked when printing reaches from 1 to 2 million characters. Although it was destroyed by peeling, the protective layer 7 having the structure as in the third embodiment could print up to 10 million characters.

Next, FIG. 4 shows a fourth embodiment of the present invention. The protective layer 7 in the fourth embodiment is formed by forming SiAlON as the oxidation resistant layer 5 on the heating element 3 in a thickness of 1 μm, and then forming CrON of 0.1 μm and SiAl of 0.1 μm on the upper surface thereof.
The intermediate layer 9 composed of a total of 20 layers is laminated by alternately repeating ON and a total of 10 times, and a coating film of CrON as the abrasion resistant layer 6 having a thickness of 2 μm is formed on the upper surface thereof. . The thickness of the protective layer 7 thus configured is 5 μm, which is about 2 μm as compared with the above-mentioned conventional example.
It is thin.

As a result of a durability test using the thermal head of the fourth embodiment having the above-mentioned structure, as in the case of the above-mentioned embodiments, initial damage such as cracking and peeling did not occur,
Practically sufficient durability was obtained. In addition, the uppermost layer of Cr
Even if the ON coating was partially peeled off, the heating element 3 was not affected and good printing results were obtained.

Further, in the conventional thermal head using the abrasion-resistant layer 6 of 3 μm and the oxidation-resistant film of 2 μm as the protective layer 7, the entire protective film is cracked and peeled off by printing 1 to 2 million characters. The thermal head formed by the protective layer 7 of the fourth embodiment had a damage of 1
It is possible to print up to 10 million characters.

Further, a total of 40 layers of CrON and SiAlON as the intermediate layer 9 having a thickness of 0.05 μm and 0.05 μm were formed in total, and a durability test was conducted. As a result, the crack resistance was further improved and the life was extended. It was confirmed.

Next, of the above-mentioned protective layer 7, SiAlO
A method of forming the oxidation resistant layer 5 made of N will be described. The conventional oxidation resistant layer 5 is formed by a method such as sputtering using Ar gas.

However, when ₂ to 15% of O ₂ gas is added to the Ar gas used for forming the oxidation resistant layer 5, the above S
The oxidation resistant layer 5 of iAlON has higher toughness and
The wear resistant layer 6 made of NY or the like has a function of absorbing thermal stress and the like.

More specifically, only the protective layer 7 is formed by the above-mentioned A.
A thermal head formed by a conventional method is mounted on a thermal transfer printer to form a film by a film forming method in which O ₂ gas is added to r gas in an amount of ₂ to 15%, and repeated printing is performed on a thermal recording paper. Then, the life test was performed. As a result, the protective layer 7 of the thermal head formed by the conventional film forming method causes an initial destruction, whereas the protective layer 7 formed by this method does not cause an initial destruction and finally a life failure. It turned out to be destroyed by.

Therefore, according to such a film forming method, it becomes possible to form the oxidation resistant layer 5 having high toughness, and even the protective layer 7 having a small film thickness can withstand the impact during high speed printing. The life of the thermal head can be extended.

Further, if 15% or more of O ₂ gas is used as Ar.
When the film is formed by sputtering in addition to the gas, the SiAlON-based layer does not serve as the oxidation resistant layer 5.

The present invention is not limited to the above embodiment, but can be modified as necessary.

For example, the number of stacked layers in the formation of the intermediate layer 9 is not limited to the number in this embodiment, and may be increased or decreased depending on the application.

[0045]

As described above, according to the present invention, since the protective layer having a small film thickness and excellent durability can be formed, the thermal response of the thermal head at the time of printing can be improved and the printing speed can be improved. And the print quality can be improved.

Further, the oxidation resistant layer is 2 to 15% in Ar gas.
By forming the film by adding O ₂ gas, the oxidation resistant layer having high toughness can be obtained, so that the life of the thermal head can be extended.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a first embodiment of a thermal head of the present invention.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the thermal head of the present invention.

FIG. 3 is a longitudinal sectional view showing a third embodiment of the thermal head of the present invention.

FIG. 4 is a vertical sectional view showing a fourth embodiment of the thermal head of the present invention.

FIG. 5 is a vertical sectional view showing a conventional thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Thermal insulation layer 3 Heating element 4a Common electrode, 4b Individual electrode 5 Oxidation resistant layer 6 Abrasion resistant layer 7 Protective layer 8 Sacrificial abrasion layer 9 Intermediate layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Tsushima 1-7 Yukiya Otsuka-cho, Ota-ku, Tokyo Alps Electric Co., Ltd.

Claims (6)

[Claims] 1. A heat retaining layer formed on a surface of a substrate, a plurality of heat generating elements formed on the heat retaining layer, individual electrodes and a common electrode for supplying electric power to each heat generating element, and the heat retaining layer. A thermal head having a protective layer laminated on each heating element and each electrode, the protective layer comprising:
An oxidation resistant layer and a wear resistant layer laminated on the oxidation resistant layer,
A thermal head comprising a sacrificial wear layer which is laminated on the wear resistant layer and has the same material as that of the oxidation resistant layer as a main component. 2. A heat insulating layer formed on a surface of a substrate, a plurality of heat generating elements formed on the heat insulating layer, individual electrodes and a common electrode for supplying electric power to each heat generating element, and the heat insulating layer. A thermal head having a protective layer laminated on each heating element and each electrode, the protective layer comprising:
A thermal head comprising an oxidation resistant layer and a wear resistant layer alternately laminated a plurality of times. 3. A heat insulating layer formed on a surface of a substrate, a plurality of heat generating elements formed on the heat insulating layer, individual electrodes and a common electrode for supplying electric power to each heat generating element, and the heat insulating layer. A thermal head having a protective layer laminated on each heating element and each electrode, the protective layer comprising:
It is formed between the lowermost oxidation-resistant layer and the uppermost wear-resistant layer and between these oxidation-resistant layer and wear-resistant layer, and is made of the same material as these oxidation-resistant layer and wear-resistant layer. And a middle layer formed by alternately laminating a coating layer having a thickness smaller than that of the abrasion resistant layer a plurality of times. 4. The wear resistant layer is formed of Cr, Ti, B, Z.
2. A nitride or oxide of at least one metal of r and Y, or a mixture of at least one of these nitrides and oxides.
The thermal head according to claim 3. 5. The oxidation resistant layer is composed of a nitride or oxide of at least one metal of Si and Al, or a mixture of at least one of these nitrides and oxides. The thermal head according to any one of claims 1 to 3. 6. A heat insulating layer formed on a surface of a substrate, a plurality of heat generating elements formed on the heat insulating layer, individual electrodes and a common electrode for supplying electric power to each of these heat generating elements, and the heat insulating layer. A method of manufacturing a thermal head having each heating element and a protective layer laminated on each electrode, wherein the oxidation resistant layer is formed by adding ₂ to 15% O ₂ gas to Ar gas. A method of manufacturing a thermal head, comprising: