JP2000318196A - Thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long life thermal head reduced in drive load by applying surface lubricity. SOLUTION: The second protective film 16 formed on the surface of a thermal head comprises a mixed material of a vanadium group element or a chromium group element and silicon oxide or a CrN material. When the thermal head is driven, the vandaium group element or chromium group element of the second protective film 16 heated by the heat from a heating resistor 13 becomes a lower oxide and lubricating effect is generated on the second protective film 16 and the surface of the second protective film becomes a lubricating function layer. Therefore, the friction of the surface of the thermal head and an ink ribbon or thermal paper is markedly reduced.

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 a long-life thermal head having a reduced driving load due to its surface having lubricity and a method of manufacturing the same. About.

[0002]

2. Description of the Related Art In general, the structure of a conventional thermal head and the method of manufacturing the same are generally arranged by linearly arranging a plurality of heating resistors at an end on a heat dissipation substrate such as alumina or silicon.
According to the desired print information, heat is generated by selectively energizing each heating resistor, and the recording is performed by coloring the heat-sensitive recording paper, or the ink is transferred to plain paper via a thermal transfer ink ribbon to form dots. This is to record the status.

FIG. 3 is a cross-sectional view of a main part showing the structure of a conventional thermal head. A ridge 1b is formed near the end 1a of a heat-radiating substrate 1 made of ceramic such as alumina by photolithography. On the upper surface of the substrate 1, a heat insulating layer 2 made of glass glaze or the like is formed by a sputtering technique. Further, Ta ₂ N or Ta-SiO _{2 is formed on} the upper surface of the heat insulating layer _2.
The heating resistors 3 are laminated by sputtering or the like, and the pattern of the heating resistors 3 is formed by photolithography so as to be linearly arranged in accordance with the number of dots. A plurality of heating units 3 are provided above the unit 1b.
a.

In order to generate heat in the heating portion 3a of the heating resistor 3, electrodes made of Al, Cu, Au or the like for supplying electric power to the heating resistor 3 are laminated by sputtering or the like. Then, a common electrode 4a connecting the plurality of heating resistors 3 on the end 1a side of the substrate 1 with the heating portion 3a interposed therebetween by a photolithography technique, and an individual electrode 4b connected to each heating resistor 3 on the opposite side. And an external connection terminal (not shown) are formed at the same time.

The heating resistor 3 and the common electrode 4
a, a protective layer 5 of high hardness made of Al-Si-ON, Si-ON or Si-N, etc. is sputtered on each surface of the individual electrode 4b to prevent oxidation and wear. To a thickness of about 5 μm. The protective layer 5 is formed so as to cover all surfaces of the common electrode 4a and the individual electrodes 4b other than the external connection terminals (not shown).

Finally, a chip-shaped thermal head is manufactured by dicing the substrate 1. like this,
Using a conventional thermal head via a thermal transfer ink ribbon,
Alternatively, in the case of heat-sensitive recording paper, the individual electrodes 4b are selectively energized based on a predetermined print signal in a state in which the recording paper is brought into direct contact with the paper conveyed directly on a platen (not shown), and By causing the heat generating portion 3a of the heat generating resistor 3 to generate heat, the ink of the ink ribbon is melted and transferred onto a sheet, or a desired recording is performed by coloring a thermosensitive recording sheet.

[0007]

However, in the conventional thermal head as described above, the heating portion 3a is
Is formed on the ridges 2a of the heat retaining layer 2 and strongly presses against a platen (not shown). A large shear stress and a large thermal stress are repeatedly applied to the protective layer 5 on the heat generating portion 3a, and there is a problem that peeling (floating) in the fatigue fracture mode is easily generated. Once the protective film 5 is peeled off at the interface with the heating resistor 3, the cermet resistor material such as Ta—SiO 2 having poor oxidation resistance is easily oxidized to increase the dot resistance, and the heating portion 3 a Does not rise to the desired temperature, the ink on the ink ribbon is not transferred at the time of printing, and missing dots occur, resulting in poor printing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and reduces the friction between a protective film and a thermal paper or an ink ribbon by using a protective film on the surface of a thermal head as a lubricating functional layer. It is an object of the present invention to provide a thermal head which prevents the occurrence of the thermal head.

[0009]

According to the present invention, there is provided a thermal head including a substrate, a heat insulating layer formed on an upper surface of the substrate, a heating resistor and an electrode on the upper surface of the heat insulating layer, and connected to the heating resistor. And a protective layer covering the surface of the heating resistor and the electrode, wherein the protective film has a first protective film having wear resistance and oxidation resistance, and a surface oxide film has self-lubricating properties. A two-layer structure in which a second protective film and a second protective film are sequentially laminated;
The first protective film is made of Al-Si-ON, Si-NO
Or Si-N, wherein the second protective film is a mixed material of a vanadium group element or a chromium group element and silicon oxide,
Alternatively, it is made of a CrN-based material. When the thermal head is driven, power is supplied from the electrodes to the heating resistor, whereby the heating resistor generates heat, and the heat heats the second protective film on the surface of the thermal head, resulting in a lubrication effect. It becomes a lubricating functional layer having This lubricating effect is considered to be caused by the vanadium group element or the chromium group element contained in the second protective film being converted to a lower oxide by heating. The chemical formula of oxidation of these elements can be expressed as, for example, 4Ta + 5O ₂ → 2Ta ₂ O ₅ when the second protective film is a mixture of Ta and SiO ₂ . The vanadium group element or the chromium group element contained in the second protective film is thermally oxidized on the surface of the protective film to form a lower oxide, and the second protective film is lubricated by the second protective film. Friction between the protective film and the ink ribbon or the thermal paper is remarkably reduced, and the shear stress and thermal stress applied to the first protective film and the heating resistor are reduced, so that peeling (floating) in the fatigue failure mode occurs. It is possible to provide a long-life thermal head without performing the above.

[0010] In the present invention, the first protective layer may include A
1-Si-ON, the second protective layer is made of Ta and SiO ₂
Therefore, it is possible to provide a thermal head excellent in the lubricating effect of the second protective film.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a thermal head and a method of manufacturing the same according to the present invention will be described. FIG. 1 is a cross-sectional view of a main part of a structure of a thermal head according to the present invention, in which a trapezoidal 15 μm-thick protruding ridge 11b is formed by photolithography near an end 11a of a heat dissipation board 11 made of silicon or the like. A heat insulating layer 12 made of glass glaze or the like is formed on the upper surface of the substrate 11 by a sputtering technique.

The upper surface of the heat insulating layer 12 is made of Ta-SiO ₂
The heat-generating resistor 13 is laminated by sputtering or the like, and the pattern of the heat-generating resistor 13 is formed by photolithography technology at predetermined intervals so as to be aligned.
A heat generating portion 13a is formed in a dot shape above the second convex portion 12a.

A heating section 13a is provided on the heating resistor 13.
An electrode 14 made of Al or the like that supplies energy for generating heat is laminated, and a common electrode 14a is formed on one side of the heating resistor 13 and an individual electrode 14b is formed on the other side. Then, the heat generating portion 13a of each heat generating resistor 13 sandwiched between the electrodes 14a and 14b generates heat by energization.

The heating resistor 13 and the common electrode 1
4a, to prevent oxidation or wear of the individual electrode 14b, the exposed surfaces of the heating resistor 13 and the electrode 14 are coated with Al-Si-ON, Si-NO, or Si-NO.
-N and a second protective layer 16 made of a mixed material of a vanadium group element, a chromium group element and silicon oxide, or a CrN-based material on the upper surface of the first protective film 15. Are sequentially laminated.

Hereinafter, examples of the protective layer of the present invention will be described. (Embodiment) In the embodiment of the thermal head according to the present invention, the first protective layer 15 is made of Al-Si-O-N having a thickness of approximately 4.5 μm, and the second protective layer 16 is formed of approximately 0.5 μm. Ta and Si
It is made of a mixed material of O ₂ (Ta-SiO ₂ ). Al-Si
The first protective layer 15 consisting of -O-N is, Si ₃ N ₄ and Al
Using a sputtering target made of a ceramic sintered body containing ₂ O ₃ as a main component, a sputter film is formed in an Ar gas atmosphere to form a second protective layer 16 made of Ta—SiO _2.
Is a film formed by sputtering in an Ar gas atmosphere using a sintered body of a mixed material of Ta and SiO ₂ as a sputtering target.

Next, the Ta-SiO prepared in the above embodiment was used.
The second protective film of the thermal head having the surface electrode 14a made of _2, when heat is generated the heat generating portion 13a by applying a power to 14b, was measured and the temperature of the head surface, the friction coefficient of the head surface. In the graph shown in FIG. 2, the horizontal axis represents the head surface temperature, and the vertical axis represents the friction coefficient of the head surface. As shown in FIG. 2, the coefficient of friction is gradually reduced with the increase of the head surface temperature, and a sufficient lubrication effect is obtained in the range of the head surface temperature when the thermal head is actually used as indicated by the shaded portion in the graph. Has occurred.

As a result of a print life comparison test, a thermal head with only the first protective layer 15 failed to print at a travel distance of 50 km (20 million characters). Means mileage 100km
No abnormalities occur until the printing of (40 million characters), and a remarkable difference in the printing life is clearly confirmed, and the occurrence of delamination at the boundary between the heating resistor 13 and the first protective film 15 is prevented. You can get the result. From this result, it was clarified that the thermal head of the present invention doubled in comparison with the conventional one and had a long life.

[0018]

As described above, in the thermal head of the present invention, the protective film has a two-layer structure of the first protective film and the second protective film, and the first protective film is made of Al-Si-O-. N, Si-N
-O or Si-N, and the second protective film on the outermost surface is made of a mixed material of a vanadium group element or a chromium group element and SiO2, or a CrN-based material. Oxidation of the vanadium-based element and the chromium-based element of the second protective film by heat from the body causes a lubricating effect on the surface of the second protective film, and the second protective film and the ink ribbon or heat-sensitive Abstract: To provide a long-life thermal head without occurrence of peeling (floating) in a fatigue failure mode, because friction with paper is significantly reduced and stress applied to the first protective film and the heating resistor is reduced. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a thermal head according to the present invention.

FIG. 2 is a schematic diagram illustrating the occurrence of a lubricating effect of the thermal head of the present invention.

FIG. 3 is a sectional view of a main part of a conventional thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11 Substrate 2, 12 Heat insulating layer 3, 13 Heating resistor 4, 14 Electrode 4a, 14a Common electrode 4b, 14b Individual electrode 5 Protective film 15 First protective film 16 Second protective film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shio Takahashi 1-7 Yukiya Otsukacho, Ota-ku, Tokyo Alps Electric Co., Ltd. (72) Inventor Noboru 1-7 1 Yukitani-Otsukacho, Ota-ku, Tokyo Alp F-term in SU-DENKI Co., Ltd. (reference) 2C065 JF03 JF07 JF10 JF12 JF15 JF16

Claims (2)

[Claims] 1. A substrate, a heat insulating layer formed on an upper surface of the substrate, a heating resistor and an electrode on the upper surface of the heat insulating layer, an electrode connected to the heating resistor, and a heating resistor and an electrode. A protective layer covering the surface, wherein the protective film has a two-layer structure in which a first protective film and a second protective film are sequentially laminated, and the first protective film is formed of Al-Si-O-N , Si-ON or Si-N, wherein the second protective film is made of a vanadium group element, a mixed material of a chromium group element and silicon oxide, or a CrN-based material. 2. The method according to claim 1, wherein the first protective layer is Al-Si-ON,
The thermal head according to claim 2, wherein the second protective layer is a mixed material of Ta and SiO _2.