JP3380745B2 - Thermal head - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various printers,
It belongs to the technical field of thermal heads for thermal recording used as recording means in plotters, fax machines, recorders and the like.

[0002]

2. Description of the Related Art For recording an ultrasonic diagnostic image, heat-sensitive recording using a heat-sensitive material comprising a film or the like as a support and a heat-sensitive recording layer is used. Further, the thermal recording has advantages that it does not require wet development processing and is easy to handle. Therefore, in recent years, not only small-sized image recording such as ultrasonic diagnosis but also CT diagnosis and MRI diagnosis are performed. In applications such as X-ray diagnosis where large and high-quality images are required, use for image recording for medical diagnosis is also under consideration.

As is well known, in heat-sensitive recording, a glaze in which heat-generating elements having a heat-generating element and an electrode for recording an image by heating a heat-sensitive recording layer of a heat-sensitive material are arranged in one direction (main scanning direction) is known. Using the formed thermal head, while the glaze is slightly pressed against the thermosensitive material (thermosensitive recording layer), the both are relatively moved in the sub-scanning direction orthogonal to the main scanning direction, and image data such as MRI is supplied. According to the image data of the recorded image supplied from the source, energy is applied to the heating element of each pixel of the glaze to generate heat, thereby heating the heat-sensitive recording layer of the heat-sensitive material to perform image recording.

A protective film is formed on the surface of the glaze of the thermal head in order to protect the heating element for heating the heat-sensitive material, electrodes, and the like. Therefore,
It is this protective film that comes into contact with the thermosensitive material during thermosensitive recording, and the heating element heats the thermosensitive material through this protective film,
As a result, thermal recording is performed. The material of the protective film, usually, in accordance with but ceramics having abrasion resistance is used, the surface of the protective film, to the heat-sensitive material and the sliding contact while being heated at the time of thermal recording, overlaying recording Wear and deteriorate.

As this abrasion progresses, density unevenness occurs in the heat-sensitive image and the strength of the protective film cannot be maintained, so that the function of protecting the heating element and the like is impaired, and finally,
The image cannot be recorded (head cut). In particular, in applications requiring high-quality and high-quality multi-gradation images such as the aforementioned medical applications, in order to achieve high quality and high image quality, support for high rigidity such as polyester film is required. With a heat-sensitive film that uses the body,
The recording temperature (applied energy) and the pressing force of the thermal head on the heat-sensitive material are set to be high. for that reason,
Compared to normal thermal recording, the force and heat applied to the protective film of the thermal head are large, and wear and corrosion (wear due to corrosion) are likely to proceed.

[0006]

As a method of preventing abrasion of the protective film of such a thermal head and improving durability, many techniques for improving the performance of the protective film have been studied, and among them, particularly As a protective film having excellent wear resistance and corrosion resistance, a protective film containing carbon as a main component (hereinafter referred to as a carbon protective film) is known.

For example, Japanese Patent Publication No. 61-53955 and Japanese Patent Publication No. 4-62866 (divided application of the above-mentioned application) disclose, as a protective film for a thermal head, a carbon protective film having a Vickers hardness of 4500 kg / mm ² or more. A thermal head in which the protective film is sufficiently thinned to realize excellent responsiveness as well as excellent wear resistance by forming the above-mentioned material, and a manufacturing method thereof are disclosed. Such a carbon protective film has characteristics extremely close to diamond,
It has extremely high hardness and is chemically stable. Therefore, excellent properties are exhibited in terms of wear resistance and corrosion resistance against sliding contact with the heat-sensitive material. However, the carbon protective film has excellent wear resistance, but is brittle because it is hard, that is, has low toughness, and cracks and peeling occur relatively easily due to heat shock and thermal stress due to heating of the heating element. There is a problem that it ends up.

With respect to such a problem, Japanese Patent Laid-Open No. 7-13
Japanese Patent No. 2628 has a protective film having a two-layer structure including a lower silicon-based compound layer and an upper diamond-like carbon layer, thereby significantly reducing abrasion and destruction of the protective film due to heat shock, A thermal head capable of high-quality recording over a long period is disclosed. Further, in the publication, the surface of the silicon-based compound layer is subjected to a surface treatment by plasma CVD or the like in a reducing atmosphere to improve the adhesion with the diamond-like carbon layer.

However, although the silicon compound layer is made of a ceramic material such as silicon nitride, generally, a film made of such a ceramic material has film-forming defects such as pinholes. Therefore, if a carbon layer is formed as it is on the surface of a silicon-based compound layer having such a film formation defect (hereinafter referred to as a defect portion), a defect portion is also formed on the carbon film, and the mechanical strength and the barrier of the portion are generated. And the carbon layer may be cracked or peeled off. In the worst case, head disconnection may occur. When the protective film is cracked or peeled off in this way, wear and corrosion, and further wear due to corrosion progress from here, and the durability of the thermal head deteriorates, exhibiting high reliability over a long period of time. It is not possible.

An object of the present invention is to solve the above-mentioned problems of the prior art. A thermal head having a protective film containing carbon as a main component, in which corrosion and wear of the protective film are extremely small, Provides a thermal head that prevents cracking and peeling of the protective film against mechanical shock and mechanical shock, has sufficient durability, and can stably perform high-quality thermal recording for a long period of time. To do.

[0011]

In order to achieve the above object, the present invention provides, as a protective film for protecting a heating element, a lower layer protective film formed on the heating element side and comprising at least one layer, and the lower layer protective film. A thermal head having an upper protective film mainly formed of carbon and formed on at least one layer, wherein a resin is applied to the surface of the lower protective film.
After that, a surface treatment is performed to expose the surface of the lower protective film,
After that, the lower protective layer is formed by forming the upper protective film.
Provided is a thermal head comprising a defective portion existing on the surface of a protective film filled with a resin .

Here, the surface treatment is a lapping treatment.
Is preferred. Further, the lower protective film is a ceramic
It is preferable that the film is composed mainly of ox.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The thermal head of the present invention will now be described in detail with reference to the preferred embodiments shown in the accompanying drawings.

FIG. 1 shows a schematic view of an example of a thermal recording apparatus using the thermal head of the present invention. A thermosensitive recording apparatus (hereinafter referred to as recording apparatus) 10 shown in FIG. 1 performs thermosensitive recording on a thermosensitive material (hereinafter referred to as thermosensitive material A) which is a cut sheet having a predetermined size such as B4 size. And a recording unit 20 for performing heat-sensitive recording on the heat-sensitive material A by the loading unit 14 in which the magazine 24 containing the heat-sensitive material A is loaded, the supply / conveyance unit 16, and the thermal head 66,
And a discharge unit 22.

In such a recording apparatus 10, one thermosensitive material A is pulled out from the magazine 24, the thermosensitive material A is conveyed to the recording section 20, and the thermal head 66 is pressed against the thermosensitive material A, while the glaze is extended. By conveying the heat-sensitive material A in the sub-scanning direction that is orthogonal to the present direction, that is, the main scanning direction (the direction perpendicular to the paper surface in FIGS. 1 and 2), each heating element generates heat in accordance with the recorded image (image data). ,
Heat-sensitive recording is performed on the heat-sensitive material A.

The heat-sensitive material A comprises a resin film such as a transparent polyethylene terephthalate (PET) film or paper as a support, and a heat-sensitive recording layer formed on one surface thereof. Such a heat-sensitive material A is formed into a laminated body (bundle) of 100 sheets or the like in a predetermined unit and is packaged in a bag body or a band. Are stored in the magazine 24 of the recording apparatus 10 and are taken out one by one from the magazine 24 for thermal recording.

The magazine 24 is a casing having a lid 26 that can be opened and closed, and accommodates the thermosensitive material A and is loaded in the loading section 14 of the recording apparatus 10. The loading unit 14 is the recording device 10
Insertion port 30 and guide plate 32 formed in the housing 28 of the
It also has guide rolls 34, 34 and a stop member 36. The magazine 24 has an insertion opening 30 with the lid 26 side first.
Is inserted into the recording device 10, is guided by the guide plate 32 and the guide roll 34, and is pushed to a position where it abuts on the stop member 36, so that the recording device 10 is loaded at a predetermined position. Further, the loading section 14 is provided with an opening / closing mechanism (not shown) for opening / closing the lid 26 of the magazine.

The supply / conveyance means 16 takes out one sheet of the heat-sensitive material A from the magazine 24 loaded in the loading section 14 and conveys it to the recording section 20, and uses a suction cup 40 for adsorbing the heat-sensitive material A by suction. Sheet-fed mechanism, transporting means 4
2, the conveyance guide 44, and the regulation roller pair 52 located at the exit of the conveyance guide 44. The transport means 42 includes a transport roller 46 and a pulley 4 coaxial with the transport roller 46.
7a, a pulley 47b and a tension pulley 47c connected to a rotary drive source, an endless belt 48 stretched around these three pulleys, and a nip roller 50 that forms a roller pair with the conveying roller 46. 40
The leading end of the heat-sensitive material A separated by the conveying roller 46
The heat sensitive material A is conveyed by being nipped by the nip roller 50 and the nip roller 50.

When a recording start instruction is issued in the recording apparatus 10, the lid 26 is opened by the opening / closing mechanism,
The sheet-fed mechanism using the suction cup 40 takes out one sheet of the heat-sensitive material A from the magazine 24, and transfers the leading end of the heat-sensitive material A to the conveying means 42.
(Roller pair consisting of transport roller 46 and nip roller 50). When the heat-sensitive material A is nipped by the conveyance roller 46 and the nip roller 50, the suction by the suction cup 40 is released, and the heat-sensitive material A supplied is guided by the conveyance guide 44 and is conveyed to the regulation roller pair 52 by the conveyance means 42. Be transported. When the heat-sensitive material A to be recorded is completely discharged from the magazine 24, the lid 26 is closed by the opening / closing means.

The distance from the conveying means 42 by the conveying guide 44 to the regulation roller pair 52 is set to be slightly shorter than the length of the heat-sensitive material A in the conveying direction. The leading edge of the heat-sensitive material A reaches the regulation roller pair 52 by the transportation by the transportation means 42,
The regulation roller pair 52 is initially stopped, and the tip of the heat-sensitive material A is temporarily stopped and positioned here. When the tip of the heat-sensitive material A reaches the regulation roller pair 52, the temperature of the thermal head 66 (glaze) is confirmed, and if the temperature of the thermal head 66 is a predetermined temperature, the regulation roller pair 5
The conveyance of the heat sensitive material A by 2 is started, and the heat sensitive material A is
It is conveyed to the recording unit 20.

The recording unit 20 includes a thermal head 66, a platen roller 60, a cleaning roller pair 56, and a guide 5.
8. A heat sink 67 for cooling the thermal head 66,
It has a cooling fan 76 and a guide 62. The thermal head 66 performs thermal recording with a recording (pixel) density of about 300 dpi capable of recording an image up to B4 size, for example. Heater element that performs one direction (main scanning direction)
It has a well-known structure in which glazes arranged in the above are formed. A heat sink 67 for cooling is fixed to the thermal head 66. Further, the thermal head 66 is supported by a support member 68 that is rotatable in a vertical direction about a fulcrum 68a. This thermal head 66
The glaze will be described in detail later. The width (main scanning direction), resolution (recording density), recording gradation and the like of the thermal head 66 of the present invention are not particularly limited, but the width is 5 cm to
It is preferable that the resolution is 50 cm, the resolution is 6 dots / mm (about 150 dpi) or more, and the recording gradation is 256 gradations or more.

The platen roller 60 rotates in the arrow direction in the drawing at a predetermined image recording speed while holding the heat-sensitive material A in a predetermined position, and in the sub-scanning direction orthogonal to the main scanning direction (arrow x direction in FIG. 2). ), The heat sensitive material A is conveyed. The cleaning roller pair 56 is a roller pair including an adhesive rubber roller (upper side in the drawing) that is an elastic body and a normal roller. The adhesive rubber roller removes dust and the like attached to the heat-sensitive recording layer of the heat-sensitive material A, It prevents dust from adhering to the glaze and adversely affecting the image recording.

In the recording apparatus 10 of the illustrated example, before the heat-sensitive material A is conveyed, the support member 68 rotates upward,
The standby position is just before the glaze of the thermal head 66 and the platen roller 60 contact each other. When the transportation by the pair of regulation rollers 52 is started, the heat-sensitive material A is
Next, it is nipped by the pair of cleaning rollers 56, and further,
It is conveyed while being guided by the guide 58. When the tip of the heat-sensitive material A is conveyed to the recording start position (the position corresponding to the glaze), the supporting member 68 rotates downward, and the heat-sensitive material A is sandwiched between the glaze and the platen roller 60,
The glaze is pressed against the recording layer, and the thermosensitive material A
Is held in a predetermined position by the platen roller 60, and is sub-scanned and conveyed by the platen roller 60 and the like.
Along with this conveyance, each of the glaze heating elements is heated in accordance with the recorded image, so that heat-sensitive recording is performed on the heat-sensitive material A.

The heat-sensitive material A, on which the heat-sensitive recording has been completed, is guided by the guide 62, is conveyed to the platen roller 60 and the conveying roller pair 63, and is ejected to the tray 72 of the ejecting section 22. The tray 72 is projected to the outside of the recording apparatus 10 through a discharge port 74 formed in the housing 28, and the heat-sensitive material A on which an image is recorded is discharged to the outside through the discharge port 74 and taken out.

FIG. 2 is a schematic sectional view of the glaze (heating element) of the thermal head 66. In the illustrated example, the glaze is formed on the substrate 80 (the thermal head 66 in the illustrated example).
Is pressed by the heat-sensitive material A from above, so that it is on the bottom in FIG. 2), the glaze layer (thermal storage layer) 82 formed thereon, the heat-generating (resistive) body 84 formed thereon, The electrode 86 is formed, and the heating element 84 formed thereon and the protective film for protecting the electrode 86 and the like are included. In the illustrated example, the protective film has a two-layer structure, and the lower protective film 88 mainly composed of ceramic is formed to cover the heating element 84 and the electrode 86,
A carbon-based protective film, such as a carbon protective film 90, formed as an upper protective film on the lower protective film 88.
(Preferably, DLC protective film = Diamond Like Carbon protective film) constitutes a protective film.

The thermal head 66 of the present invention can have basically the same structure as that of a known thermal head except for this protective film. Therefore, the layer structure other than that and the material of each layer are not particularly limited, and various known materials can be used. Specifically, the substrate 80 is made of heat-resistant glass or an electrically insulating material such as ceramics such as alumina, silica, magnesia, the glaze layer 82 is made of heat-resistant glass or a heat-resistant resin such as polyimide resin, and the heating element 84 is used. Various heating resistors such as nichrome (Ni-Cr), tantalum, and tantalum nitride, and various conductive materials such as aluminum, gold, silver, and copper can be used as the electrode 86. For the glaze (heating element), vacuum deposition, CVD (Chemical Vapo
r Deposition), a thin film type heating element formed by using a so-called thin film forming technique such as sputtering and a photo-etching method, and a thick film formed by a so-called thick film forming technique by printing and baking such as screen printing and etching. Although a mold heating element is known, the thermal head 66 used in the present invention may be formed by any method.

As described above, the thermal head 6 of the illustrated example
6 has a two-layered protective film including a carbon protective film 90 and a lower protective film 88. By having such a lower protective film, more preferable results can be obtained in terms of wear resistance, corrosion resistance, corrosion wear resistance, etc., and a thermal head having higher durability and long life can be realized. As the lower protective film 88 formed on the thermal head 66 of the present invention, a material having heat resistance, corrosion resistance and abrasion resistance which can be a protective film for a thermal head is used as a known protective film for a thermal head. Various materials can be used, but preferably various ceramic materials can be used.

Specifically, silicon nitride (Si ₃ N ₄ ) and silicon carbide
(SiC), tantalum oxide (Ta ₂ O ₅ ), aluminum oxide (Al ₂
O ₃ ), sialon (SiAlON), lasion (LaSiON), silicon oxide (SiO ₂ ), aluminum nitride (AlN), boron nitride (BN),
Selenium oxide (SeO), titanium nitride (TiN), titanium carbide (Ti
C), titanium carbonitride (TiCN), chromium nitride (CrN), and mixtures thereof are exemplified. Above all, silicon nitride, silicon carbide, sialon and the like are preferably used from the viewpoints of easiness of film formation, manufacturing suitability such as manufacturing cost, and balance between mechanical wear and chemical wear. Further, the lower protective film 88 may contain a trace amount of additives such as a semimetal and a metal described later for the purpose of adjusting physical properties. The method for forming the lower protective film 88 is not particularly limited, and the lower protective film 88 is formed by a known method for forming a ceramic film (layer) using the thick film forming technique or the thin film forming technique described above.

The thickness of the lower protective film 88 is not particularly limited, but is preferably about 0.2 μm to 20 μm, more preferably about 2 μm to 15 μm. By setting the thickness of the lower protective film 88 within the above range, preferable results are obtained in that the wear resistance and the thermal conductivity (that is, recording sensitivity) can be favorably balanced. Further, the lower protective film 88 may have a multi-layered structure. When the lower protective film 88 has a multi-layered structure, it may have a multi-layered structure using different materials, or may have a multi-layered structure having the same material and layers having different densities, or both. It may be one.

The thermal head 66 of the present invention has a two-layer structure having an upper protective film on such a lower protective film 88. With such a two-layer structure, a thermal head having better durability can be obtained due to the synergistic effect of both protective films. As the upper protective film, heat resistance that can serve as a protective film for the thermal head,
As long as the material has corrosion resistance and abrasion resistance, various materials used as a protective film for a known thermal head can be used, but in the illustrated example, as a preferred embodiment, carbon containing carbon as a main component is used. It has a protective film 90. As a result, excellent wear resistance and corrosion resistance of the carbon protective film 90 can be obtained, and the two-layer structure suppresses cracking and peeling of the carbon protective film 90 due to heat shock and thermal stress to some extent. It is possible to

However, as described above, film defects (defects) such as pinholes may exist in the lower protective film 88. Therefore, when the upper protective film such as the carbon protective film 90 is directly formed on the surface of the lower protective film 88 having such a defective portion, the unevenness of the surface of the carbon protective film 90 due to the shape of the defective portion 89 and the defect. Deterioration of the physical properties of the carbon protective film 90 near the portion 89
This may cause cracking or peeling of the carbon protective film 90. If the protective film is cracked or peeled off in this way, wear and corrosion, and further wear due to corrosion progress from this point, and the durability of the thermal head deteriorates.

In order to solve such a problem, the thermal head 66 of the present invention, as shown in FIG. 2, has a lower protective film 88.
The defect portion 89 existing on the surface is filled with the resin B. That is, the defective portion 89 is filled with the resin B, and the carbon protective film 90, which is the upper protective film, is formed on the lower protective film 88 having a flat surface without any defect, so that the carbon protective film 90 is formed. The surface of the carbon protective film 90 can be made flat while ensuring sufficient adhesion to the lower protective film 88 of the film 90. Therefore, on the surface of the carbon protective film 90,
Since it is possible to prevent defects in the carbon protective film 90 due to the defective portion 89 and obtain a uniform film, the mechanical shock applied to the surface of the carbon protective film 90 is uniformly dispersed without being locally concentrated, and the carbon It is possible to effectively prevent the protective film 90 from being cracked or peeled off.

Moreover, as described above, the carbon protective film 9
Since 0 is chemically very stable, it is possible to effectively prevent chemical corrosion of the lower protective film 88, which is a ceramic film, and prolong the life of the thermal head. Therefore, the thermal head 66 of the present invention has sufficient durability in combination with the above-described effects associated with the filling of the resin into the defective portion 89, and exhibits high reliability over a long period of time, which results in high reliability over a long period of time. The heat-sensitive recording of image quality can be stably performed. In particular, as in the medical applications described above, the thermosensitive film using a highly rigid support such as a polyester film has sufficient durability even in the application of recording under high energy and high pressure, High reliability can be demonstrated for a long period of time.

The method of filling the defective portion 89 with a resin is not particularly limited, and various methods can be adopted. Basically, the method is performed by applying a resin on the surface of the lower protective film 88. I'll do it. The coating process of the resin B on the lower protective film 88 in this case is shown in FIGS. In FIG. 3, (a) shows the state before the resin B is applied,
(B) is after application of resin B, (c) is after surface treatment,
(D) shows after the carbon protective film 90 is formed.

Specifically, as shown in FIG. 3 (a), the resin B is applied to the surface of the lower protective film 88 having the defective portion 89 as shown in FIG. 3 (b). Then, as shown in FIG. 3C, the applied resin B
(Unnecessary resin other than that filled in the defective portion 89) is removed by surface treatment to once expose the surface of the lower protective film 88, and then the carbon protective film 9 as shown in FIG.
It is preferable to form 0 for the reason that the adhesion between the lower protective film 88 and the carbon protective film 90 can be sufficiently secured, but as the structure for directly forming the carbon protective film 90 on the surface of the applied resin. Good.

The method of applying the resin is not particularly limited and may be appropriately determined depending on the form of the resin. For example, if the resin is in a solid state such as solid wax, the resin is applied to the lower protective film 88.
Apply by moving while pressing
In the case of a liquid resin, various known methods such as spray coating, brush coating and dip coating are exemplified. Alternatively, a solid resin may be dissolved or dispersed in water, an organic solvent or the like to be in a liquid state and applied by spray coating, brush coating or the like.

Further, when applying the resin, various auxiliary treatments may be carried out in order to densely fill the defective portion 89 with the resin without leaving a gap. For example, a method of applying while applying a heat pulse to the thermal head, an ultrasonic impregnation method, a method of applying under a pressure or reduced pressure atmosphere, a method of using these in combination, and the like are exemplified.

The resin that can be used is not particularly limited as long as it can be applied, and various known resins can be used, for example, those used as a coating agent for the protective film of the thermal head. Suitable examples include: Specifically, polyethylene, polyolefins such as polypropylene and polystyrene, polyvinyl chloride, vinyl resins such as polyvinyl alcohol and carboxy-modified polyvinyl alcohol, phenol resins, fluororesins, polyamides, polyimides, polyacetals, (meth) acrylic resins, Various resins such as polycarbonate, urea resin, saturated or unsaturated polyester, urethane resin, alkyd resin, epoxy resin, and silicone resin; various fiber materials such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose;
Proteins such as starch and gelatin; various waxes such as paraffin wax, microcrystalline wax, caderin wax, carnauba wax, rice wax, lanolin, and montan wax; metal soaps such as zinc stearate and calcium stearate; higher fatty acids, Examples thereof include ceramic coating agents containing ceramics such as higher fatty acid amide, silica and alumina as the main components;

Two or more kinds of these resins may be mixed, and if necessary, various additives such as a filler and a surfactant may be contained. The resin may of course be diluted with a solvent or water to adjust the viscosity suitable for the coating operation.

After the resin has been applied in this manner, prior to the formation of the carbon protective film 90, the applied resin B is dried and then, as shown in FIG.
(Unnecessary resin other than that filled in the defective portion 89) is removed to expose the surface of the lower protective film 88. The method for removing the resin is not particularly limited, and various methods can be used. For example, a method of performing a lapping treatment, a method of performing an etching treatment, and the like can be cited. Among them, the lapping treatment is most preferable in that the resin can be efficiently removed by the simplest operation.

When the resin is removed by the lapping process, the lapping film may be used to polish the surface of the applied resin. As a wrapping sheet, dry resin can be removed by polishing,
Moreover, if the surface of the lower protective film 88 is not too rough (even if unevenness due to polishing is not too large) even when the resin is removed and the lower protective film 88 is exposed,
It is not particularly limited. Specifically, # 4000
To # 15000 are preferably exemplified, and as the material, alumina wrapping sheet and the like are preferably exemplified.
The polishing process of the lower protective film 88 with such a wrapping sheet can be performed mechanically or manually. The mechanical polishing can be performed, for example, by passing a wrapping sheet with the thermal head coated with resin mounted on the printer.

Thus, the lower protective film 88 in which the defective portion 89 is filled with the resin and the surface of which is exposed if necessary.
As shown in FIG. 3D, a carbon protective film 90 containing carbon as a main component is formed on the above. In the illustrated thermal head 66, a carbon protective film 90, for example, a DLC protective film is used as a protective film containing carbon as a main component. In the present invention, the protective film containing carbon as a main component means a carbon protective film containing more than 50 atm% of carbon. As such a carbon protective film,
A carbon protective film composed of carbon and unavoidable impurities is preferable, and more preferably a high-purity carbon protective film containing very little or no unavoidable impurities, for example, a DLC protective film. Here, examples of the unavoidable impurities include a gas used in the process such as argon (Ar) and a residual gas in the vacuum chamber such as oxygen. However, it is preferable that these gas components are mixed as little as possible. The content is preferably 2 atm% or less, and more preferably 0.5 atm% or less.

In the present invention, as an additive component other than carbon for forming a carbon protective film containing carbon as a main component, substances such as hydrogen, nitrogen and fluorine, Si, Ti, Zr and H are used.
Preferable examples are semimetals and metals such as f, V, Nb, Ta, Cr, Mo and W. When the additive component is a substance such as hydrogen, nitrogen and fluorine, it is preferable that the content thereof in the carbon protective film containing carbon as the main component is less than 50 atm%, and the additive component is Si or Ti.
In the case of a semimetal or a metal such as the above, the content of these in the carbon protective film containing carbon as a main component is preferably 20 atm% or less. In the following description, the carbon protective film 90 will be described as a representative example of the carbon-based protective film, but it goes without saying that the description is also applicable to other carbon-based protective films. There is no such thing.

Since such a carbon protective film 90 is chemically very stable, it is possible to effectively prevent chemical corrosion of the lower protective film 88 and prolong the life of the thermal head as described above. Is. Carbon protective film 9
The hardness of 0 is not particularly limited as long as it has sufficient hardness as a protective film of the thermal head. For example, a Vickers hardness of 3000 kg / mm ^{2 to} 5000 kg / mm ² is preferably exemplified. Further, this hardness may be constant or changed in the thickness direction of the carbon protective film 90. When the hardness is changed in the thickness direction of the carbon protective film 90, this hardness change May be continuous or stepwise.

The method of forming such a carbon protective film 90 is not particularly limited, and it can be formed by a known thick film forming technique or thin film forming technique, but preferably by plasma CVD using a hydrocarbon gas as a reaction gas. Examples include a method of forming a hard carbon film and a method of forming a hard carbon film by sputtering using a carbon material such as a sintered carbon material or a glassy carbon material as a target material.

FIG. 4 shows a conceptual diagram of a sputtering apparatus for forming the carbon protective film 90. The sputtering apparatus 100 is basically configured to have a vacuum chamber 102, a gas introduction part 104, a sputtering means 106, and a substrate holder 108.

The vacuum chamber 102 is preferably formed of a non-magnetic material such as SUS304 so that the magnetic field of the cathode 112, which will be described later, is not affected. Further, the vacuum chamber 1 used for forming the carbon protective film 90 of the present invention.
02 is the ultimate pressure of the initial exhaust gas of 2 × 10 ⁻⁵ Torr or less, preferably 5 × 10 ⁻⁶ Torr or less, and 1 × 10 ⁻⁴ Torr during film formation.
It is preferable to have a vacuum sealability that achieves ˜1 × 10 ⁻² Torr. As the vacuum exhaust means 110 attached to the vacuum chamber 102, an exhaust means combining a rotary pump, a mechanical booster pump, and a turbo pump is preferably exemplified, and an exhaust means using a diffusion pump or a cryopump instead of the turbo pump. Is also preferably exemplified. The evacuation capacity and number of the vacuum evacuation unit 110 may be appropriately selected according to the volume of the vacuum chamber 102, the gas flow rate during film formation, and the like. Further, in order to increase the exhaust speed, the exhaust speed may be adjusted by adjusting the exhaust resistance of the pipe using a bypass pipe or by providing an orifice valve and adjusting the opening degree.

The gas introduction part 104 is a part for introducing a gas for generating plasma. The introduction part uses a stainless pipe or the like vacuum-sealed with an O-ring or the like to introduce the gas into the vacuum chamber 102. To do. Further, the amount of gas introduced is controlled by a known method such as a mass flow controller. The gas introducing unit 104 is basically configured to wipe out the gas in the vicinity of the plasma generation region in the vacuum chamber 102. Further, it is preferable that the blowing position is optimized so as not to affect the distribution of generated plasma. As a gas for plasma generation for forming the carbon protective film 90, for example, an inert gas such as helium, neon, argon, krypton, or xenon is used, but among them, in view of price and easy availability. Argon gas is preferably used.

In the sputtering, the target material 114 to be sputtered is arranged on the cathode 112, the cathode 112 is set to a negative potential, and plasma is generated on the surface of the target material 114 to eject the target material 114 (atoms thereof). A film is formed by adhering to and depositing on the surfaces of the substrates (that is, the glaze of the thermal head 66) arranged facing each other. The sputtering means 106 has the cathode 112, a target material 114 arrangement portion, a shutter 116, and the like.

When plasma is generated on the surface of the target material 114, the negative side of the DC power source 118 is directly connected to the cathode 112 and a DC voltage of 300V to 1000V is applied. The output of the DC power supply 118 is 1 kW to
A range of about 10 kW, which has a necessary and sufficient output for forming the carbon protective film 90, may be appropriately selected. The shape of the cathode 112 may be appropriately determined according to the shape of the substrate on which the carbon protective film 90 is formed. Also, in terms of arc prevention, etc., 2 kHz to 20 kHz
A DC power supply that is pulse-modulated in z can also be suitably used.
A high frequency power source can also be used to generate plasma. When a high frequency power source is used, a high frequency voltage is applied to the cathode 112 via a matching box to generate plasma. In that case, impedance matching is performed by a matching box and adjustment is performed so that the reflected wave of the high frequency voltage is 25% or less of the incident wave. As a high frequency power supply, industrial 13.56MH
In the range of 1 kW to 10 kW for z, one having an output necessary and sufficient for forming the carbon protective film 90 may be appropriately selected.

The target material 114 may be directly fixed to the cathode 112 by using In-based solder or mechanical fixing means, but normally, the backing plate 120 made of oxygen-free copper or stainless steel is fixed to the cathode 112. Then, the target material 114 is attached thereon as described above. In addition, the cathode 112 and the backing plate 1
20 is configured to be water-coolable, whereby the target material 114 is indirectly water-cooled. The carbon protective film 9
As the target material 114 used for forming 0, a sintered carbon material, a glassy carbon material, or the like is preferably exemplified. Further, its shape may be appropriately determined according to the shape of the substrate.

The carbon protective film 90 is formed in the cathode 1
Magnetron sputtering, in which a magnet 112a such as a permanent magnet or an electromagnet is arranged inside 12 and a magnetic field is formed on the surface of the target material 114 to confine plasma for sputtering, can also be suitably used. This magnetron sputtering is preferable in that the film formation rate is high. The shapes and positions of the permanent magnets and electromagnets, the number, the strength of the generated magnetic field, and the like are appropriately determined according to the thickness and thickness distribution of the carbon protective film 90 to be formed, the shape of the target material 114, and the like. Further, it is preferable to use, as the permanent magnet, a magnet capable of generating a high magnetic field, such as an Sm-Co magnet or an Nd-Fe-B magnet, because plasma can be sufficiently confined.

The substrate holder 108 is the thermal head 66.
Is fixed, and the glaze to be the substrate is fixed so as to face the cathode 112. In addition, the glaze may be configured to be rotatable or movable with respect to the cathode 112, if necessary, and may be appropriately selected according to the size of the substrate and the like. There is no particular limitation on the distance between the substrate and the target material 114, and a distance at which the film thickness distribution is uniform may be selected and set within a range of about 20 mm to 200 mm.

When the thermal head 66 used in the present invention is manufactured, in order to further improve the adhesion between the carbon protective film 90 and the lower protective film 88, the lower protective film 88 is formed prior to the formation of the carbon protective film 90. Preferably, the surface of the is etched with plasma. Therefore, in the sputtering apparatus 100 of the illustrated example, a bias power supply 122 for applying a high frequency voltage is connected to the substrate holder 108. The bias power source 122 applies a high frequency voltage to the substrate via a matching box, and may be appropriately selected from industrial ones at 13.56 MHz and about 1 kW to 5 kW. Further, the strength of etching may be based on the bias voltage applied to the substrate as a guide, and normally, it may be appropriately optimized in the range of negative 100V to 500V.

FIG. 5 shows a conceptual view of another example of a film forming apparatus for forming the carbon protective film 90. The film forming apparatus 13 of the illustrated example
0 is basically the vacuum chamber 132 and the gas introduction unit 1
34, the first sputtering means 136, the second sputtering means 138, the plasma generating means 140, the bias power source 142, and the substrate holder 144. Such a film forming apparatus 130 has two film forming means by sputtering and a film forming means by plasma CVD in the system, that is, in the vacuum chamber 132, and the thermal head 66 as a film forming substrate is taken out from the system. By sputtering with different targets, or by sputtering and plasma CVD
With, it is possible to continuously form films having different compositions. Therefore, by using the film forming apparatus 130,
It is possible to continuously form a plurality of different layers without opening the atmospheric pressure in the system, etc., and it is possible to manufacture an efficient thermal head.

The vacuum chamber 132 is preferably formed of a non-magnetic material such as SUS304 so that the cathode 118, which will be described later, and the magnetic field for plasma generation will not be affected. The vacuum chamber 132 used for forming the carbon protective film 90 of the thermal head 66 of the present invention has an ultimate pressure of initial exhaust of 2 × 10 ⁻⁵ Torr or less, preferably 5 ×.
10 ^-6 Torr or less, 1 × 10 ^-4 Torr to 1 × 10 ^-2 during film formation
It is preferable to have a vacuum sealability that achieves Torr. Evacuation means 146 attached to the vacuum chamber 132
As the above, the same as the vacuum exhaust means 110 of the sputtering apparatus 100 can be used.

A part of the vacuum chamber 132 where the arc is generated by the plasma or the electromagnetic wave for generating the plasma may be covered with an insulating member, if necessary. MC nylon, PTFE (polytetrafluoroelastomer)
Ethylene) , PPS (polyphenylene sulfide), PE
N (polyethylene naphthalate), PET (polyethylene terephthalate), etc. can be used. In addition, PEN
When PET, PET, or the like is used, the degree of vacuum may be lowered by degassing from the insulating member, so care must be taken when using such a material.

The gas introduction part 134 includes two gas introduction pipes 1.
It has 34a and the gas introduction pipe 134b. The gas introduction pipe 134a is a pipe for introducing a gas for generating plasma, while the gas introduction pipe 134b is a pipe for introducing a reaction gas of plasma CVD, and both of them are vacuum-sealed with an O-ring or the like. Gas is introduced into the vacuum chamber 132 using a stainless steel pipe or the like. Further, the amount of gas introduced is controlled by a known method such as a mass flow controller. Both of the gas introduction pipes 134a and 134b are optimized so that the gas is wiped out to the vicinity of the plasma generation region in the vacuum chamber 132 within a possible range and the distribution of the generated plasma is not affected. preferable. In particular, the blowing position of the gas introducing pipe 134b of the reaction gas influences the film thickness distribution, so it is preferable to optimize it according to the shape of the substrate (the glaze of the thermal head 66) and the like.

As the gas for generating plasma, those exemplified for the sputtering apparatus 100 may be used. On the other hand, examples of the reaction gas for generating the carbon protective film 90 by plasma CVD include hydrocarbon compound gases such as methane, ethane, propane, ethylene, acetylene, and benzene. In addition, both the gas introduction pipe 134a and the gas introduction pipe 134b need to adjust the sensor of the mass flow controller according to the gas used.

First sputtering means 136 and second
The sputtering means 138 both form a film on the surface of the substrate by the above-described sputtering, and the first sputtering means 136 has a cathode 148, a target material 150 arrangement portion, a shutter 152, a DC power supply 154, and the like. Consists of Also, the cathode 148
A magnet 148a is arranged inside, and a backing plate 162 for fixing the target material 150 is further attached. On the other hand, the second sputtering means 138 includes a cathode 156, an arrangement portion of the target material 150, and a shutter 158.
And a DC power supply 160 and the like. Similarly, a magnet 156a is arranged in the cathode 156, and further,
Backing plate 16 for fixing target material 150
4 is attached. Such first sputtering means 1
36 and the second sputtering means 138 are both the sputtering means 10 of the sputtering apparatus 100.
It is the same as 6.

In the film formation by plasma CVD, direct current discharge, high frequency discharge, direct current arc discharge, micro ECR wave discharge, etc. can be used as the plasma generating means.
Among them, the micro ECR wave discharge has a high plasma density,
It is advantageous for high-speed film formation, and particularly suitable for forming the carbon protective film 90 in that it can be formed at low temperature. The film forming apparatus 130 of the illustrated example utilizes microwave ECR wave discharge as a film forming means of the carbon protective film 90 by plasma CVD, and the plasma generating means 140 includes a microwave power source 166, a magnet 168, and a microwave waveguide. 170, coaxial converter 172, dielectric plate 174, radial antenna 17
6 and the like.

The DC discharge generates plasma by applying a negative DC voltage between the substrate and the electrode. The DC power supply used for the DC discharge has a power of about 1 to 10 kW and may be appropriately selected to have a sufficient output necessary for forming the carbon protective film 90. Further, in terms of arc prevention and the like, a DC power supply which is pulse-modulated at 2 kHz to 20 kHz can also be suitably used. High-frequency discharge is achieved by applying high-frequency voltage to the electrodes through the matching box.
Generate plasma. In that case, impedance matching is performed by a matching box and adjustment is performed so that the reflected wave of the high frequency voltage is 25% or less of the incident wave. As a high frequency power source for high frequency discharge, 1 for industrial use
A material having an output necessary and sufficient for the target film formation may be appropriately selected in the range of about 1 kW to 10 kW at 3.56 MHz. Also, a pulse-modulated high frequency power source can be used. A DC arc discharge uses a hot cathode to generate a plasma. Tungsten, lanthanum boride (LaB ₆ ) or the like can be used as the hot cathode. Further, DC arc discharge using a hollow cathode can also be used. The DC power supply used for DC arc discharge is 1
In the range of about kW to about 10 kW and about 10 to 150 A, it is possible to appropriately select one having a necessary and sufficient output for the target film formation.

Microwave ECR discharge is a combination of microwave and E
Plasma is generated by CR magnetic field,
As described above, the plasma generating means 140 in the illustrated example generates plasma by this microwave discharge. 2.45 GHz for industrial use as the microwave power source 166
In the range of 1 kW to 3 kW, the carbon protective film 90
What has necessary and sufficient output for film formation may be appropriately selected. Further, for the ECR magnetic field generation, a permanent magnet or an electromagnet capable of forming a desired magnetic field may be appropriately used. In the illustrated example, an Sm-Co magnet is used as the magnet 168. For example, when a microwave of 2.45 GHz is used, the ECR magnetic field is 875 G (Gauss), so a magnet whose magnetic field in the plasma generation region is 500 G to 2000 G may be used. The microwave is introduced into the vacuum chamber 132 by the microwave waveguide 170 and the coaxial converter 17.
2, using the dielectric plate 174 and the like. In addition, the formation state of the magnetic field and the introduction path of the microwave are different from those of the carbon protective film 90.
Since it affects the distribution of the film thickness to be formed, it is preferable to optimize the film thickness so as to be uniform.

The substrate holder 144 is the thermal head 66.
Is to fix. Here, the film forming device 130 is
The substrate holder 144 has one film forming means, that is, the film forming means, that is, the sputtering means 136 and 138, and the plasma generating means 14 for performing plasma CVD.
The substrate holder 144 is held by the rotating substrate 180 that swings so that the glaze to be the substrate can be opposed to 0.
It may be appropriately selected according to the size of the substrate and the like. Further, a heater may be provided on the upper surface of the substrate holder 144 so that film formation is performed while heating. Substrate and target material 150 or radial antenna 17
The distance to 6 is not particularly limited and may be selected and set within a range of about 20 mm to 200 mm so that the film thickness distribution becomes uniform.

Here, even when the apparatus of the illustrated example is used,
In order to improve the adhesion between the carbon protective film 90 and the lower protective film 88, it is preferable to etch the surface of the lower protective film 88 with plasma before forming the carbon protective film 90. Further, in order to obtain a hard film by plasma CVD, it is necessary to form a film while applying a negative bias voltage to the substrate. Therefore, the film forming apparatus 130 includes the substrate holder 1
A bias power source 14 for applying a high frequency voltage to
2 is connected. The bias power source 142 applies a high frequency voltage to the substrate through a matching box, and may be appropriately selected from industrial ones at 13.56 MHz and about 1 kW to 5 kW.

The strength of the etching may be determined by using the bias voltage applied to the substrate as a guide, and normally, a negative voltage of 100 V to
The optimization may be appropriately performed within the range of 500V. Further, it is preferable to use a self-bias voltage of a high frequency voltage in plasma CVD. Self-bias voltage is negative 1
It is 00V-500V.

Although the thermal head of the present invention has been described in detail above, the present invention is not limited to the above-mentioned example, and it goes without saying that various improvements and changes may be made.

[0068]

EXAMPLES The present invention will be described in more detail with reference to specific examples of the present invention.

Example 1 <Pretreatment of Silicon Nitride Film> First, prior to forming the upper protective film, a thermal head (KGT-260-12MPH8 manufactured by Kyocera Corp.) was used.
The surface of the glaze (the surface of the silicon nitride film) was subjected to the following pretreatment. In addition, in the thermal head which is the base of this, a silicon nitride film (Si ₃ N ₄ ) having a thickness of 11 μm is formed as a protective film on the surface of the glaze. Therefore, in this embodiment, this silicon nitride film is the lower protective film 88, and the lower protective film 88 is subjected to the following pretreatment, and then the carbon protective film 90 which becomes the upper protective film is the lower protective film 88.
Is formed in the upper layer. As a base thermal head, a thermal head in which a small number of defective portions 89 could be confirmed in the lower protective film 88 was used.

On the surface of the lower protective film (silicon nitride film) 88 of the thermal head, a brush was used to apply a polyimide resin (Treney, manufactured by Toray Industries, Inc.). After the applied resin was dried, the surface of the thermal head (glaze) on which the resin was applied was polished with a # 8000 lapping sheet to remove excess resin applied until the surface of the lower protective film 88 was exposed. Specifically, it was performed by passing a B4 size wrapping sheet by 3 m in a state where the base thermal head coated with the resin was mounted on the printer. Thus, a carbon protective film 90 was formed by sputtering on the surface of the lower protective film 88 in which the defective portion 89 was filled with the resin.

<Formation of Carbon Protective Film> A carbon protective film 90 is formed on the surface of the lower protective film 88 thus pretreated by using the sputtering apparatus 100 shown in FIG. The thermal head 66 of the present invention having the glaze shown in FIG. The details of the sputtering apparatus 100 are as follows.

A. Vacuum chamber 102 SUS3 having, as the vacuum exhaust means 110, a rotary pump having an exhaust speed of 1500 L (liter) / min, a mechanical booster pump having an exhaust speed of 12000 L / min, and a turbo pump having an exhaust speed of 3000 L / sec, respectively.
A vacuum chamber 102 made of 04 and having a volume of 0.5 m ³ was used. An orifice valve is arranged in the suction portion of the turbo pump so that the opening degree can be adjusted to 10 to 100%.

B. The gas introducing unit 104 is configured by using a mass flow controller having a maximum flow rate of 100 to 500 [sccm] and a stainless pipe having a diameter of 6 mm. The joint between the stainless pipe and the vacuum chamber 102 was vacuum-sealed with an O-ring. Argon gas was used as the plasma generating gas when the carbon protective film 90 described below was formed.

C. Sputtering means 106 An Sm-Co magnet was placed inside as a permanent magnet 112a,
A rectangular cathode 112 having a width of 600 mm and a height of 200 mm was used. As the backing plate 120, oxygen-free copper processed into a rectangular shape was used, and the cathode 112 was attached using In-based solder. Further, by cooling the inside of the cathode 112 with water, the magnet, the cathode 112, and the back surface of the backing plate 120 were cooled. As the power supply 118, a DC power supply with a maximum output of 8 kW and a negative potential was used. The DC power supply is constructed so that it can be modulated in a pulse shape in the range of 2 kHz to 10 kHz.

D. Substrate holder 108 Substrate (that is, glaze 82 of thermal head 66)
The distance between the target material 114 and the target material 114 is adjustable between 50 mm and 150 mm. The distance between the substrate and the target material 114 was 100 mm when the carbon protective film 90 shown below was formed. In addition, the holding portion of the thermal head by the substrate was set to a floating potential so that a high frequency voltage for etching could be applied.

E. Bias power supply 122 A high frequency power supply was connected to the substrate holder 108 via a matching box. The high frequency power supply has a frequency of 13.56M
At Hz, the maximum output is 3 kW. Further, the high frequency power supply is configured such that the high frequency output can be adjusted in the negative range of 100 V to 500 V by monitoring the self bias voltage.

In such a sputtering apparatus 100, the thermal head 66 which has been pretreated as described above.
The thermal head 66 was fixed to the substrate holder 108 in the vacuum chamber 102 so that the glaze 82 of the No. 2 faced the target material 114. In addition, masking was applied in advance to portions other than the portion where the upper protective film of the thermal head was formed (that is, other than glaze). After fixing the thermal head, the pressure in the vacuum chamber 102 is 5 × 10 5.
Evacuated to ^-6 Torr. While continuing vacuum evacuation, the argon gas is introduced by the gas introduction unit 104,
The pressure in the vacuum chamber 102 was adjusted to 5.0 × 10 ⁻³ Torr by an orifice valve installed in the turbo pump. Then, apply a high frequency voltage to the substrate,
The lower protective film (silicon nitride film) was etched at a self-bias voltage of −300 V for 10 minutes.

After the etching is completed, a sintered graphite material as the target material 114 is fixed to the backing plate 120 (attached with In-based solder), and the vacuum chamber 1
The flow rate of the argon gas and the orifice valve are adjusted so that the pressure in 02 becomes 5 × 10 ⁻³ Torr, and the shutter 11
DC power of 0.5 is applied to the target material 114 with 6 closed.
kW was applied for 5 minutes. Next, while maintaining the pressure inside the vacuum chamber 102, the DC power is set to 5 kW and the shutter 116 is opened to form a carbon protective film 90 of 2 μm.
Then, the carbon protective film 90 having a thickness of 2 μm was formed as an upper protective film by sputtering until The film thickness of the carbon protective film 90 was controlled by the film forming time by calculating the film forming speed in advance, calculating the film forming time for achieving the predetermined film thickness. In this way, five thermal heads of the present invention having the carbon protective film 90 with a thickness of 2 μm were manufactured.

<Performance Evaluation> The thermal recording apparatus shown in FIG. 1 was used to measure B4 of the five thermal heads thus prepared, using a thermal sensitive material (dry image recording film CR-AT manufactured by Fuji Photo Film Co., Ltd.). A thermal recording test of size was conducted for each 500 sheets. As a result, in any of the thermal heads, the carbon protective film 90 was not cracked or peeled off, and almost no abrasion was observed, which showed good durability and stable high-quality images without uneven density. I was able to record.

[Comparative Example 1] 5 was carried out in the same manner as in Example 1 except that the carbon protective film 90 was formed as it was without coating any resin on the surface of the lower protective film 88 having the defective portion 89. A base thermal head was prepared. The performance of each of the thermal heads produced was evaluated in the same manner as in Example 1. As a result, in each of the thermal heads, the carbon protective film 90 was peeled off at about two places in the defective portion 89 of the lower protective film 88.

Example 2 <Pretreatment of Silicon Nitride Film> The same thermal head as in Example 1 was used as a base thermal head, and in the same manner as in Example 1, resin coating, lapping sheet polishing, etc. Was pretreated on the surface of the lower protective film 88 of the thermal head 66.

<Formation of Carbon Protective Film> A carbon protective film 90 is formed on the surface of the lower protective film 88 thus pretreated by using the film forming apparatus 130 shown in FIG. The thermal head 66 of the present invention having the glaze shown in 2 was produced. The details of the film forming apparatus 130 are as follows.

A. Vacuum chamber 132 The same chamber as the vacuum chamber 102 of the sputtering apparatus 100 was used.

B. Gas introduction part 134 The same thing as the gas introduction part 104 of the sputtering apparatus 100 was used. When forming the carbon protective film 90 described later, argon gas was used as a plasma generating gas.

C. First sputtering means 136 and second sputtering means 138 Sputtering means 106 of sputtering apparatus 100
The same configuration was used.

D. Plasma generation means 140 A microwave power source 166 having an oscillation frequency of 2.45 GHz and a maximum output of 1.5 kW was used. The microwave was guided to the vicinity of the vacuum chamber 132 by the microwave waveguide 170, converted by the coaxial converter 172, and then introduced into the radial antenna 176 in the vacuum chamber 132. The plasma generator has a width of 60
A rectangle having a size of 0 mm and a height of 200 mm was used. Furthermore, E
The CR magnetic field uses a plurality of Sm-Co magnets as the magnet 168.
It was formed by arranging according to the shape of the dielectric plate 174.

E. Substrate holder 144 The same one as in Example 1 was used. The substrate holder 144 is held on the rotating substrate 180. Further, when the carbon protective film 90 is formed, the substrate and the radial antenna 17 are
The distance from 6 was 150 mm.

F. Bias power source 142 A high frequency power source was connected to the substrate holder 144 via a matching box. The high frequency power supply has a frequency of 13.56M
At Hz, the maximum output is 3 kW. Further, the high frequency power supply is configured such that the high frequency output can be adjusted in the negative range of 100 V to 500 V by monitoring the self bias voltage. Further, in the film forming apparatus 130, the bias power source 142 also serves as the substrate etching means.

Using the film forming apparatus 130 as described above, carbon was used as an upper protective film on the glaze surface of the thermal head (the same as in Example 1) which had been subjected to the above-described pretreatment as described below. The protective film 90 was formed. Therefore,
Similar to the first embodiment, the silicon nitride film is the lower protective film 88.
Then, a carbon protective film 90 serving as an upper protective film is formed thereon.

The thermal head was fixed to the substrate holder 144 in the vacuum chamber 132 so that the glaze faced the radial antenna 176. In addition, masking was applied in advance to portions other than the portion where the upper protective film of the thermal head was formed (that is, other than glaze). After fixing the thermal head, the pressure in the vacuum chamber 132 is 5 × 10 5.
Evacuated to ^-6 Torr. While continuing evacuation, methane gas is introduced by the gas introduction part 134a,
The pressure in the vacuum chamber 132 was adjusted to 5.0 × 10 ⁻³ Torr by an orifice valve installed in the turbo pump. Next, the microwave power source 142 is driven to introduce microwaves into the vacuum chamber 132 to generate microwave ECR plasma, and a high frequency voltage is applied to the substrate, and a lower layer protection is performed at a self-bias voltage of −300 V for 10 minutes. The film (silicon nitride film) was etched.

After the etching is completed, the self-bias voltage is set to −
While continuing to apply a high frequency voltage of 300 V, methane gas was introduced so that the pressure in the vacuum chamber 132 was 5.0 × 10 ⁻³ Torr and plasma CVD was performed to protect the carbon with a thickness of 2 μm as an upper protective film. The film 90 was formed. The film thickness of the carbon protective film 90 was controlled by the film forming time by calculating the film forming speed in advance, calculating the film forming time for achieving the predetermined film thickness. In this way, the thickness is 2μ
Five thermal heads of the present invention having m carbon protective film 90 were manufactured.

<Performance Evaluation> With respect to each of the five thermal heads of the present invention thus manufactured, the same performance evaluation as in Example 1 was performed by the thermal recording apparatus of FIG. As a result, in any of the thermal heads, the carbon protective film 90 was not cracked or peeled off, and almost no wear was observed.

[Comparative Example 2] Five thermal heads were prepared in the same manner as in Example 2 except that the carbon protective film 90 was formed as it was without coating any resin on the surface of the lower protective film 88. It was made. With respect to each of the obtained thermal heads, the same performance evaluation as in the example was performed. As a result, in any of the thermal heads, the carbon protective film 90 was peeled off at about two places in the defective portion 89 of the lower protective film 88. From the above results, the effect of the present invention is clear.

[0094]

As described above in detail, according to the present invention, corrosion and wear of the protective film are extremely small, and cracking and peeling of the protective film are preferably generated against heat and mechanical shock. By preventing it, it is possible to realize a thermal head having sufficient durability and capable of stably performing high-quality heat-sensitive recording for a long period of time. In particular, it has sufficient durability and long-term use even in applications where recording is performed under high energy and high pressure, for heat-sensitive films that use highly rigid supports such as polyester films used in medical applications. High reliability can be demonstrated over.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an example of a thermal recording apparatus using a thermal head of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a heating element of the thermal head of the present invention.

FIG. 3 is a conceptual diagram showing a step of applying a resin to the thermal head shown in FIG. (A) is before application of resin,
(B) shows after application of the resin, (c) shows after surface treatment, and (d) shows after formation of the carbon protective film.

FIG. 4 is a conceptual diagram of an example of a sputtering apparatus for forming a carbon protective film of a thermal head of the present invention.

FIG. 5 is a conceptual diagram of an example of a film forming apparatus for forming a carbon protective film of the thermal head of the present invention.

[Explanation of symbols]

10 (Thermal) recording device 14 Loading section 16 Supply / Transportation Means 20 recording section 22 Discharge part 24 magazines 66 thermal head 80 substrates 82 Glaze layer 84 Heating element 86 electrodes 88 Lower protective film 90 Carbon protective film 100 sputtering equipment 102, 132 vacuum chamber 104,134 Gas introduction section 106 sputtering means 108, 144 substrate holder 110,146 vacuum evacuation means 112,148,156 cathode 114,150 Target material 116, 152, 158 shutters 118,154,160 DC power supply 120, 162, 164 backing plate 122,142 Bias power supply 130 film forming apparatus 136 First Sputtering Means 138 Second sputtering means 140 Plasma generating means 166 Microwave power supply 170 Microwave introduction tube 172 coaxial converter 174 Dielectric plate 176 radial antenna 180 rotating substrate A heat sensitive material B resin

Continuation of the front page (56) Reference JP-A-7-132628 (JP, A) JP-A-62-179956 (JP, A) JP-A-59-169870 (JP, A) Jitsukaihei 3-50442 (JP , U) Actual Kaihei 1-171646 (JP, U) Actual Kaihei 5-58294 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2/335

Claims (3)

(57) [Claims] 1. A protective film for protecting a heating element, which comprises a lower protective film formed on the heating element side and formed of at least one layer, and carbon formed on the lower protective film and formed of at least one layer as a main component. A thermal head having an upper protective film for applying a resin to the surface of the lower protective film , and then performing a surface treatment.
To expose the surface of the lower protective film, and then to protect the upper layer.
Exists on the surface of the lower protective film by forming a protective film
The thermal head is characterized in that the defective portion is filled with resin . 2. The thermal head according to claim 1 , wherein the surface treatment is a lapping treatment. Wherein the lower protective layer is a thermal head according to claim 1 or 2, characterized in that a film composed mainly of ceramics.