JP2976374B2 - Thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to various printers,
It belongs to the technical field of a thermal head for performing thermal recording used as a recording means in a plotter, a facsimile, a recorder, and the like.

[0002]

2. Description of the Related Art Thermal recording using a thermal material formed by forming a thermal recording layer using a film or the like as a support is used for recording an ultrasonic diagnostic image. In addition, thermal recording has advantages such as no need for wet development processing and easy handling, and in recent years, in recent years, not only small-sized image recording such as ultrasonic diagnosis but also CT diagnosis and MRI diagnosis have been performed. For applications requiring large and high-quality images, such as X-ray diagnosis and the like, the use for image recording for medical diagnosis is also being studied.

As is well known, in thermal recording, a glaze in which a heating element having a heating element and electrodes is arranged in one direction (main scanning direction) for recording an image by heating a thermosensitive recording layer of a thermosensitive material. While the glaze is slightly pressed against the heat-sensitive material (heat-sensitive recording layer) using the formed thermal head, while moving both relatively in the sub-scanning direction orthogonal to the main scanning direction, image data supply such as MRI is performed. In accordance with 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.

In the glaze of this thermal head, 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 or the electrodes. Therefore,
It is this protective film that comes into contact with the thermosensitive material during thermal recording, and the heating element heats the thermosensitive material through the protective film,
Thus, thermal recording is performed. The material of the protective film is usually made of a ceramic having wear resistance, but the surface of the protective film slides on the heat-sensitive material in a heated state during the heat-sensitive recording. And deteriorate.

[0005] If the wear progresses, density unevenness occurs in the thermal image or the strength of the protective film cannot be maintained, so that the function of protecting the heating element and the like is impaired.
Image recording cannot be performed (head shortage). In particular, in applications where high-quality and high-quality multi-gradation images are required, such as in the medical applications described above, a high-rigidity support such as a polyester film is used in order to achieve high quality and high image quality. Using 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 higher. for that reason,
Compared to normal thermal recording, the force and heat applied to the protective film of the thermal head are greater, and wear and corrosion (wear due to corrosion) are more likely to progress.

[0006]

As a method for preventing the abrasion of the protective film of the thermal head and improving the durability, many techniques for improving the performance of the protective film have been studied. 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, JP-B-61-53955 and JP-B-4-62866 (divisional applications of the above-mentioned application) disclose a carbon protective film having a Vickers hardness of 4500 kg / mm ² or more as a protective film for a thermal head. By disposing a thermal head, a thermal head that realizes excellent responsiveness by sufficiently thinning a protective film together with excellent wear resistance, and a method of manufacturing the same are disclosed. Such a carbon protective film has characteristics very similar to diamond, has extremely high hardness, and is chemically stable.
Therefore, it exhibits excellent characteristics in terms of abrasion resistance and corrosion resistance against sliding contact with a heat-sensitive material. However, while the carbon protective film has excellent wear resistance, it is brittle because of its hardness, that is, its toughness is low, and cracking and peeling occur relatively easily due to heat shock or thermal stress caused by heating of the heating element. There is a problem that it is.

To solve such a problem, Japanese Patent Application Laid-Open No.
No. 2628 has a two-layer structure of a lower silicon-based compound layer and an upper layer of a diamond-like carbon layer, thereby greatly reducing wear and breakage of the protective film due to heat shock or the like. A thermal head capable of performing high-quality recording for a long time is disclosed. In the same publication, the adhesion of the silicon-based compound layer to the diamond-like carbon layer is improved by subjecting the surface of the silicon-based compound layer to a surface treatment in a reducing atmosphere by plasma CVD or the like.

[0009] Nevertheless, the adhesion between the diamond-like carbon layer and the silicon-based compound layer is still insufficient, and the stress due to the difference in the coefficient of thermal expansion of each of these layers, the heat-sensitive material and the thermal head (glaze) during recording, There is also a problem that cracks and peeling are caused by mechanical shocks and the like caused by foreign substances mixed in between. If the protective film is cracked or peeled in this way, wear, corrosion, and even wear due to corrosion will progress from this point, and the durability of the thermal head will be reduced. It cannot be demonstrated.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a thermal head having a protective film containing carbon as a main component. Provides a thermal head that has sufficient durability and can stably perform high-quality thermal recording over a long period of time by preventing cracking and peeling of the protective film against mechanical and mechanical shocks Is to do.

[0011]

In order to achieve the above object, the present invention provides a protective film for protecting a heating element, which is formed on the heating element side and has at least one lower layer mainly composed of ceramics. A thermal head, comprising: a film; an intermediate protective film formed on the lower protective film and including at least one layer; and an upper protective film containing carbon as a main component.

Here, the intermediate layer protective film preferably contains, as a main component, at least one selected from the group consisting of a group 4A metal, a group 5A metal, a group 6A metal, Si and Ge. Also, the thickness of the intermediate layer protective film is 0.05
μm to 2 μm, and the thickness of the upper protective film is 0.5 μm.
It is preferably from m to 5 μm. Further, by performing a lapping process and an etching process on the surface of the lower protective film, the value of the surface roughness Ra of the surface is reduced to 1 nm.
It is preferable that the intermediate layer protective film is formed thereafter. Further, it is preferable that the lower protective film is composed of at least one of a nitride and a carbide.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a thermal head according to the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

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

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

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

The magazine 24 is a housing having a lid 26 that can be opened and closed. The magazine 24 stores the heat-sensitive material A and is loaded into the loading section 14 of the recording apparatus 10. The loading unit 14 includes the recording device 10
Insertion hole 30 formed in housing 28 of
And guide rolls 34, 34, and a stop member 36. The magazine 24 is inserted into the insertion port 30 with the lid 26 side first.
Then, while being guided by the guide plate 32 and the guide roll 34 and being pushed to a position where it comes into contact with the stop member 36, the recording device 10 is loaded into a predetermined position of the recording device 10. The loading section 14 is provided with an opening / closing mechanism (not shown) for opening and closing the lid 26 of the magazine.

The supply / transportation means 16 takes out one heat-sensitive material A from the magazine 24 loaded in the loading section 14 and transports it to the recording section 20, and uses a suction cup 40 which adsorbs the heat-sensitive material A by suction. Single wafer mechanism, conveyance means 4
2, a transport guide 44, and a pair of regulating rollers 52 located at the exit of the transport guide 44. The conveying means 42 includes a conveying roller 46 and a pulley 4 coaxial with the conveying roller 46.
7a, a pulley 47b and a tension pulley 47c connected to a rotary drive source, an endless belt 48 stretched over the three pulleys, and a nip roller 50 forming a roller pair with the transport roller 46. 40
The leading end of the heat-sensitive material A sheet-fed by the conveying roller 46
And the nip roller 50 to transport the heat-sensitive material A.

When a recording start instruction is issued in the recording device 10, the lid 26 is opened by the opening / closing mechanism,
The sheet-feeding mechanism using the suction cup 40 takes out one heat-sensitive material A from the magazine 24 and transports the front end of the heat-sensitive material A to the conveying means 42.
(A roller pair composed of the transport roller 46 and the 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 supplied heat-sensitive material A is guided by the conveyance guide 44 to the regulating roller pair 52 by the conveyance means 42. Conveyed. When the heat-sensitive material A to be used for recording is completely discharged from the magazine 24, the lid 26 is closed by the opening / closing means.

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

The recording section 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 at a recording (pixel) density of about 300 dpi, for example, capable of recording an image up to a maximum of B4 size. Except for having a characteristic of the protective film, thermal recording on the thermal material A is performed. Heating element is one direction (main scanning direction)
Has a known configuration in which glazes are arranged. A heat sink 67 for cooling is fixed to the thermal head 66. The thermal head 66 is supported by a support member 68 that is rotatable up and down around a fulcrum 68a. This thermal head 66
Will be described later in detail. 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 5 cm.
Preferably, the recording density is 50 cm, the resolution is 6 dot / mm (about 150 dpi) or more, and the recording gradation is 256 or more.

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

In the illustrated recording apparatus 10, before the heat-sensitive material A is conveyed, the support member 68 rotates upward,
This is a standby position immediately before the glaze of the thermal head 66 comes into contact with the platen roller 60. When the conveyance by the above-described regulating roller pair 52 is started, the heat-sensitive material A
Next, it is nipped by the cleaning roller pair 56,
It is transported while being guided by the guide 58. When the leading end of the heat-sensitive material A is conveyed to the recording start position (the position corresponding to the glaze), the support 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 heat-sensitive material A
While being held at a predetermined position by the platen roller 60, the sheet is transported in the sub-scanning direction by the platen roller 60 and the like.
With this conveyance, each of the glaze heating elements is heated according to the recorded image, so that thermal recording is performed on the thermal material A.

The heat-sensitive material A on which the heat-sensitive recording has been completed is conveyed to the platen roller 60 and the conveying roller pair 63 while being guided by the guide 62, and is discharged to the tray 72 of the discharge section 22. The tray 72 protrudes outside 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 is taken out.

FIG. 2 is a schematic cross-sectional view of the glaze (heating element) of the thermal head 66. In the illustrated example, the glaze is 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 formed on the lower side in FIG. 2), a heat generation (resistance) body 84 formed thereon, and a heat generation (resistance) body 84 formed thereon It has an electrode 86 to be formed, and a protective film for protecting the heating element 84 and further the electrode 86 and the like formed thereon. In the illustrated example, the protective film has a three-layer structure, and includes a lower protective film 88 mainly composed of ceramic and formed to cover the heating element 84 and the electrode 86;
An intermediate layer 89 as an intermediate layer protective film, which is a characteristic part of the present invention, formed on the lower protective film 88, and a carbon-based protective film formed as an upper protective film on the intermediate layer 89. For example, the carbon protective film 90 (preferably, DLC
The protective film is composed of the protective film (Diamond Like Carbon protective film).

The thermal head 66 of the present invention can have basically the same configuration as a known thermal head except for this protective film. Therefore, there is no particular limitation on the other layer configuration and the material of each layer, and various known materials can be used. Specifically, the substrate 80 is made of an electrically insulating material such as heat-resistant glass, ceramics such as alumina, silica, and magnesia, and the glaze layer 82 is made of a heat-resistant glass or a heat-resistant resin such as a polyimide resin. As the electrode 86, various kinds of conductive materials such as aluminum, gold, silver, and copper can be used as the heating resistor such as nichrome (Ni-Cr), tantalum, and tantalum nitride. The glaze (heating element) includes vacuum evaporation and 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 using a so-called thick film forming technique by printing and firing such as screen printing and baking. Although a type 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 shown in FIG.
6 has a three-layered protective film including a carbon protective film 90, an intermediate layer 89, and a lower protective film 88. By having such a lower protective film, more preferable results can be obtained in terms of abrasion resistance, corrosion resistance, corrosion resistance and the like, and a more durable and long-life thermal head can be realized. . The lower protective film 88 formed on the thermal head 66 of the present invention is not particularly limited as long as it is mainly composed of ceramics, which is a material having heat resistance, corrosion resistance and abrasion resistance that can be a protective film of the thermal head. Instead, various ceramic materials can be used.

Specifically, silicon nitride (Si ₃ N ₄ ), silicon carbide
(SiC), tantalum oxide (Ta ₂ O ₅ ), aluminum oxide (Al ₂
O ₃ ), sialon (SiAlON), ration (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. Among them, it is particularly preferable to use nitrides and carbides from the viewpoints of ease of film formation, manufacturing aptitude such as manufacturing cost, balance between mechanical abrasion and chemical abrasion, and silicon nitride, silicon carbide, sialon, and the like. Is preferably used. Further, the lower protective film may contain a small amount of an additive such as a semi-metal or metal described later for adjusting the physical properties. There is no particular limitation on the method of forming the lower protective film 88, and the lower protective film 88 is formed by a known method of forming a ceramic film (layer) using the above-described thick film forming technology, thin film forming technology, or the like.

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, a favorable result can be obtained in that a balance between abrasion resistance and thermal conductivity (that is, recording sensitivity) can be appropriately obtained. Further, the lower protective film 88 may have a multilayer structure. When the lower protective film 88 has a multi-layer structure, the lower protective film 88 may have a multi-layer structure using different materials, or may have a multi-layer structure having different layers of the same material with different densities or both. It may be something.

The thermal head 66 of the present invention has a protective film having a structure in which an intermediate layer 89 is formed on such a lower protective film 88 and a carbon protective film 90 containing carbon as a main component is formed thereon. Thereby, the excellent wear resistance and corrosion resistance of the carbon protective film 90 can be obtained, and the above-mentioned heat shock, thermal stress, cracking and peeling of the carbon protective film 90 can be suppressed to some extent.

As described above, in the case where only one carbon protective film 90 is formed on the lower silicon nitride film, sufficient adhesion to the lower layer (lower protective film 88 in the illustrated example) can be obtained. In other words, it cannot withstand stress due to the difference in thermal expansion coefficient from the lower layer, mechanical shock due to impurities, and the like, and cracks and peeling still occur. In order to solve such a problem, the thermal head 66 of the present invention has a three-layer structure in which an intermediate layer 89 is further provided between the lower protective film 88 and the carbon protective film 90, so that the lower protective film It has been found that the adhesion, shock absorption, and the like of the protective film 90 are significantly improved, and the durability of the thermal head is improved.

Further, 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 to prolong the life of the thermal head. Accordingly, the thermal head 66 of the present invention has sufficient durability in combination with the above-described functions provided by the provision of the intermediate layer 89, and exhibits high reliability over a long period of time. Can be stably performed. In particular, it has sufficient durability even in applications where recording under high energy and high pressure is performed on a heat-sensitive film using a highly rigid support such as a polyester film as in the medical applications described above. High reliability can be exhibited over a long period of time.

The intermediate layer 89 formed on the thermal head 66 of the present invention comprises a metal of Group 4A (Group 4 = titanium group), a metal of Group 5A (Group 5 = vanadium group), and a group 6A (6 Group = chromium group) metal, Si (silicon) and Ge
The upper layer is made of at least one selected from the group consisting of (germanium).
This is preferable from the viewpoint of the adhesion to the lower protective film 88, which is the lower layer, and the durability of the carbon protective film 90. Specifically, Si, Ge, Ti (titanium), Ta (tantalum), Mo (molybdenum), a mixture thereof and the like are preferably exemplified. Among them, particularly, Si and Mo are preferable, and most preferably, Si is preferable in terms of bonding with carbon. There is no particular limitation on the method for forming the intermediate layer 89, and the intermediate layer 89 may be formed by a known film forming method according to the material for forming the intermediate layer 89, using the above-described thick film forming technology or thin film forming technology.
As a preferred example, sputtering is exemplified, and plasma CVD can also be suitably used. Further, the intermediate layer 89 may have a multilayer structure. When the intermediate layer 89 has a multilayer structure, it may have a multilayer structure using different materials, or may have a multilayer structure having different layers of the same material with different densities, or both. It may be.

Here, prior to the formation of the intermediate layer 89, the surface of the lower protective film 88 is subjected to a surface treatment such as a lapping process or an etching process to obtain a surface roughness Ra.
Preferably, the surface is roughened until the value falls within a predetermined range. By doing so, the lower protective film 88 and the intermediate layer 8 are formed.
9, the intermediate layer 89 and the carbon protective film 90
Can be further improved, and the durability of the thermal head can be further improved.

Specifically, the Ra value indicating the surface roughness is 1n
Preferably, the surface treatment is performed until the thickness becomes from m to 0.4 μm, and more preferably the Ra value is from 1 nm to 0.05 μm. When the Ra value is less than 1 nm, the effect of improving the adhesion by the surface treatment is not particularly observed. When the Ra value exceeds 0.4 μm, the carbon protective film 90 is formed via the intermediate layer 89 when the carbon protective film is formed. Unevenness is also generated on the surface of the thermal head 90, and wear of the thermal head may easily progress. Incidentally, at this time, it is necessary to perform the surface treatment so that the Ra value becomes smaller than the value of the thickness of the lower protective film. It is needless to say that the thermal head 66 of the present invention can have sufficient durability without performing such lapping processing and etching processing.

The Ra value in the present specification is the center line average roughness, and the Ra value in the direction of the center line is obtained from a roughness curve obtained by two-dimensionally measuring the surface shape of the lower protective film 88. A portion having a measurement length l is sampled, the center line of the sampled portion is defined as the X axis, the direction of the vertical magnification is defined as the Y axis, and the roughness curve is defined as y = f.
When expressed by (x), the value calculated by the following equation (1) was used, but z = f (x,
y) is measured, and a portion of the area s is extracted, and the following equation (2) is obtained.
May be used.

(Equation 1)

The method of surface treatment in this case is not particularly limited as long as the above-mentioned Ra value can be obtained, and various conventionally known methods can be used. Preferably, a treatment is performed. In this case, the surface of the lower protective film 88 is first roughened to a predetermined roughness by a lapping process, the surface area is increased, and then a surface which can be oxidized by oxygen or the like in the atmosphere is removed by an etching process, so that a relatively simple process is performed. By this method, the adhesiveness between the intermediate layer 89 and the upper protective film 90 can be further improved.

As a lapping method, a known lapping sheet may be used to polish the lower protective film 88 of the thermal head mechanically or manually. When mechanical polishing is performed, the polishing may be performed by passing the wrapping sheet while the lower protective film 88 of the thermal head is in contact with the wrapping sheet. The type of the wrapping sheet is the same as that of the above R
There is no particular limitation as long as the value a can be obtained.
000 to # 20000 are preferable, and # 4000 to # 15000 are more preferable. On the other hand, as a method of the etching treatment, it may be performed by a sputtering device or the like described later.

On the intermediate layer 89 thus formed on the lower protective film 88, a carbon protective film 90 containing carbon as a main component is formed. In the illustrated example of the thermal head 66, as a protective film containing carbon as a main component,
A carbon protective film 90, for example, a DLC protective film is used. In the present invention, the protective film containing carbon as a main component is
A carbon protective film containing more than 50 atm% of carbon is referred to. As such a carbon protective film, a carbon protective film composed of carbon and unavoidable impurities is preferable, and more preferably, the content of unavoidable impurities is extremely small or High-purity carbon protective film not containing at all, for example, DL
C protective film is good. Here, the inevitable impurities include a gas used in the process such as argon (Ar) and a residual gas in a vacuum chamber such as oxygen, but the mixing of these gas components is preferably as small as possible. It is preferably set to 2 atm% or less, more preferably 0.5 atm% or less.

In the present invention, as an additional component other than carbon which forms the carbon protective film containing carbon as a main component, substances such as hydrogen, nitrogen and fluorine, Si, Ti, Zr, H
Preferable examples include semimetals and metals such as f, V, Nb, Ta, Cr, Mo, and W. When the additional components are substances such as hydrogen, nitrogen and fluorine, the content of these in the carbon protective film containing carbon as a main component is preferably less than 50 atm%.
And the like, it is preferable that the content of these in the carbon protective film containing carbon as a main component is 20 atm% or less. In the following description, the carbon protective film 90 will be described as a representative example of the protective film containing carbon as a main component. However, it is needless to say that the description is applicable to other protective films containing carbon as a main component. 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 extend the life of the thermal head as described above. It 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. The hardness may be constant or changed with respect to the thickness direction of the carbon protective film 90. When the hardness is changed in the thickness direction of the carbon protective film 90, the hardness may vary. May be continuous or stepwise.

The method for forming the carbon protective film 90 is not particularly limited, and is formed by a known thick film forming technique or thin film forming technique. Preferably, the carbon protective film 90 is formed by plasma CVD using a hydrocarbon gas as a reaction gas. 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 are exemplified.

Here, the formation of the carbon protective film 90 may be performed while heating. By doing so, the adhesion between the carbon protective film 90 and the intermediate layer 89 and further to the lower protective film 88 can be further improved, and cracks due to heat shock due to annealing of the heating element and mechanical shock due to entry of foreign matter during thermal recording can be prevented. It is possible to obtain more excellent durability against delamination and deterioration or disappearance of the carbon film due to high power recording.

The heating temperature is preferably from 50 ° C. to 400 ° C., and more preferably the operating temperature range of the thermal head 66, for example, from 100 ° C. to 250 ° C. Within such a temperature range, the adhesion to the intermediate layer 89 and the durability of the carbon protective film 90 itself become the best. As a heating method, a heater is provided on the upper surface of a substrate holder of a film forming apparatus such as a sputtering apparatus or a plasma CVD apparatus, and the substrate is heated by placing the substrate on the heater. A method of heating the surface of the intermediate layer 89 by causing the thermal head 66 itself to generate heat is preferably exemplified.
Other than these, various heating methods can be adopted,
There is no particular limitation.

In such a thermal head of the present invention, the thickness of the intermediate layer 89 and the carbon protective film 90 is not particularly limited, but the thickness of the intermediate layer 89 is 0.05 μm to 2 μm. And more preferably 0.1 μm to 1 μm.
The thickness of 0 is preferably 0.5 μm to 5 μm, more preferably 1 μm to 3 μm. Middle layer 8
9 is too thick with respect to the carbon protective film 90, the intermediate layer 8
If the intermediate layer 89 is too thin, on the contrary, if the intermediate layer 89 is too thin, it is necessary to ensure a sufficient thickness for the unevenness formed on the surface of the lower protective film 88 by lapping and etching. And the function as the intermediate layer 89 cannot be sufficiently exhibited, which is not preferable. Accordingly, by setting both the thickness of the intermediate layer 89 and the thickness of the carbon protective film 90 within the above-mentioned predetermined range, the adhesive force and the shock absorbing force to the lower layer of the intermediate layer 89 and the carbon protective film 90 have Functions such as durability can be realized in a well-balanced manner.

FIG. 3 is a conceptual diagram of a film forming apparatus for forming the intermediate layer 89 and the carbon protective film 90. The illustrated film forming apparatus 100 basically includes a vacuum chamber 102, a gas introduction unit 104, a first sputtering unit 106, a second sputtering unit 108, and a plasma generation unit 11.
0, a bias power supply 112, and a substrate holder 114. Such a film forming apparatus 100 has two film forming means by sputtering and film forming means by plasma CVD in a system, that is, in a vacuum chamber 102, and takes out a thermal head 66 as a film forming substrate from the system. Without using an intermediate layer 89 and a carbon protective film 90 by sputtering using a different target or by sputtering and plasma CVD.
Can be continuously formed. Therefore, the film forming apparatus 1
By using 00, it is possible to form a plurality of different layers continuously without releasing the atmospheric pressure in the system, etc.
An efficient thermal head can be manufactured.

The vacuum chamber 102 is preferably formed of a non-magnetic material such as SUS 304 so that a cathode 118 and the like, which will be described later, and a magnetic field for generating plasma are not affected. In addition, the vacuum chamber 102 used for forming the intermediate layer 89 and the carbon protective film 90 of the thermal head 66 of the present invention has an initial exhaust pressure of 2 × 10 ⁻⁵ Torr or less, preferably 5 × 10 ⁻⁶ Torr or less. , 1 × 10 during film formation
^It is preferable to have a vacuum sealing property to achieve ^-4 Torr to 1 × 10 ^-2 Torr. As the evacuation means 116 attached to the vacuum chamber 102, an evacuation means combining a rotary pump, a mechanical booster pump, and a turbo pump is preferably exemplified, and an evacuation means using a diffusion pump or a cryopump instead of the turbo pump. Are also preferably exemplified. The evacuation capacity and number of the evacuation means 116 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 a pipe using a bypass pipe, or by providing an orifice valve and adjusting the opening degree thereof.

The location of the vacuum chamber 102 where the arc is generated by the plasma or the electromagnetic wave for plasma generation may be covered with an insulating member, if necessary. As the insulating member, MC nylon, Teflon (PTFE), PPS
(Polyphenylene sulfide), PEN (polyethylene naphthalate), PET (polyethylene terephthalate) and the like can be used. When using PEN, PET, or the like, care must be taken when using such a material because the degree of vacuum may be reduced by degassing from the insulating member.

The gas introduction unit 104 includes two gas introduction pipes 1
04a and a gas introduction pipe 104b. The gas introduction tube 104a is a tube for introducing a gas for generating plasma, while the gas introduction tube 104b is a tube for introducing a plasma CVD reaction gas, and both of them are vacuum-sealed with an O-ring or the like. Gas is introduced into the vacuum chamber 102 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 gas inlet pipes 104a and 104b should both be optimized to wipe off gas to the extent possible in the vicinity of the plasma generation area within the vacuum chamber 102 and not affect the distribution of the generated plasma. preferable. In particular, the position at which the reactant gas is blown out of the gas introduction pipe 104b also affects the film thickness distribution, so it is preferable to optimize the position according to the shape of the substrate (glaze of the thermal head 66).

The gas for generating the plasma for forming the intermediate layer 89 and the carbon protective film 90 includes, for example,
An inert gas such as helium, neon, argon, krypton, or xenon is used. Among them, argon gas is particularly preferably used in terms of cost and availability. On the other hand, as a reaction gas for forming the carbon protective film 90, a gas of a hydrocarbon compound such as methane, ethane, propane, ethylene, acetylene, or benzene is exemplified, and a reaction gas for forming the intermediate layer 89 is exemplified. Examples include various gases including a material for forming the intermediate layer 89. In addition, the gas introduction pipe 104a and the gas introduction pipe 104b
In both cases, it is necessary to adjust the sensors of the mass flow controller according to the gas used.

In sputtering, a target material to be sputtered is arranged on the cathode, the cathode is set to a negative potential, and plasma is generated on the surface of the target material, so that the target material (its atoms) is flipped out and arranged oppositely. A film is formed by attaching and depositing it on the surface of the substrate (ie, the glaze of the thermal head 66). The first sputtering means 106 and the second
Both of the sputtering means 108 form a film on the substrate surface by such sputtering.
The sputtering means 106 has a cathode 118, an arrangement portion of the target material 120, a shutter 122, a high-frequency power supply 124, and the like.
8 is an arrangement portion of the cathode 126 and the target material 120,
It has a shutter 128, a DC power supply 130, and the like. As described above, the first sputtering unit 106 and the second sputtering unit 108 have basically the same configuration except for the power supply and the arrangement position.
A case where the intermediate layer 89 is formed by the first sputtering means 106 and the carbon protective film 90 is formed by the second sputtering means 108 is performed as a typical example, but the present invention is not limited to this.

In the illustrated film forming apparatus 100, when generating the plasma on the surface of the target material 120, the high frequency power supply 124 is used to form the intermediate layer 89 by the first sputtering means 106 and the second sputtering means. 1
When the carbon protective film 90 is formed in step 08, the DC power supply 130 is used. In the case where the high frequency power supply 124 is used in the first sputtering means 106, plasma is generated by applying a high frequency voltage to the cathode 118 via the matching box. 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. The high-frequency power supply 124 may have a frequency of 13.56 MHz for industrial use or higher, for example, a frequency of 2 to 3 times that of 1 to 10 kW, preferably 1 to 10 kW.
In the range of about kW to 5 kW, an output having a sufficient and necessary output for forming the intermediate layer 89 may be appropriately selected. Note that the shape of the cathode 118 may be appropriately determined according to the shape of the substrate and the like. On the other hand, when the DC power supply 130 is used in the second sputtering means 108, the negative side of the DC power supply 130 is directly connected to the cathode 126.
, And a DC voltage of 300 V to 1000 V is applied. The output of the DC power supply 130 is 1 kW to 10 kW
It is only necessary to select a film having a sufficient output which is necessary for forming the carbon protective film 90. Further, a DC power supply pulse-modulated at 2 kHz to 20 kHz can be suitably used in terms of arc prevention and the like.

In the film forming apparatus 100 shown in FIG.
In the sputtering means 106, the intermediate layer 89 is formed using a high-frequency power supply 124 as a power supply for plasma generation, and in the second sputtering means 108, a carbon protective film 90 is formed using a DC power supply 130 as a power supply for plasma generation. However, the present invention is not limited to this,
The two sputtering units 106 and 108 may be arranged in reverse. Alternatively, the carbon protective film 90 may be formed by the first sputtering unit 106 using the high frequency power supply 124, and the intermediate layer 89 may be formed by the second sputtering unit 108 using the DC power supply 130. Or both sputtering means 10
6 and 108 may be reversed. Further, a DC power supply may be used for both of the sputtering means 106 and 108 as a power supply for generating plasma, the intermediate layer 89 may be formed on one side, and the carbon protective film 90 may be formed on the other side. On the other hand, the carbon protective film 9
0 may be formed. When a Si layer is formed as the intermediate layer 89, the target material 12 such as a Si single crystal is used.
It is preferable to use a high-frequency power source as a sputtering power source for generating plasma on the surface of the zero.

The target material 120 may be directly fixed to the cathode 118 using In-based solder or mechanical fixing means, but usually, a backing plate 132 (second sputtering means) made of oxygen-free copper, stainless steel or the like is used. 10
At 8, the backing plate 134) is fixed to the cathode 118, and the target material 120 is fixed thereon as described above. In addition, the cathode 118 and the backing plate 132 are configured to be water-coolable, whereby the target material 120 is also indirectly water-cooled. As the target material 120 used for forming the intermediate layer 89, a 4A group,
Preferable examples include metals of Group 5A and Group 6A, and single crystals of Ge and Si. As the target material 120 used for forming the carbon protective film 90, a sintered carbon material, a glassy carbon material, or the like is preferably exemplified. Note that the shape of the target material 120 may be appropriately determined according to the shape of the substrate.

The intermediate layer 89 and the carbon protective film 90 are formed by disposing a magnet 118 a (126 a) such as a permanent magnet or an electromagnet inside the cathode 118,
Magnetron sputtering, in which a magnetic field is formed on the surface to confine plasma and perform sputtering, can also be suitably used. This magnetron sputtering is preferable in that the film forming speed is high. The shape and position and number of the permanent magnets and electromagnets, the strength of the generated magnetic field, etc. are determined by the thickness and thickness distribution of the intermediate layer 89 and the carbon protective film 90 to be formed, the target material 1
It is determined as appropriate according to the shape of 20 and the like. Further, it is preferable to use a magnet capable of generating a high magnetic field such as a Sm-Co magnet or a Nd-Fe-B magnet as the permanent magnet since plasma can be sufficiently confined.

In the film formation by plasma CVD, a DC discharge, a high-frequency discharge, a DC arc discharge, a micro ECR wave discharge, or the like can be used as a plasma generating means.
In particular, DC arc discharge and micro ECR wave discharge have a high plasma density and are advantageous for high-speed film formation. The illustrated film forming apparatus 100 uses micro ECR wave discharge as a means for forming the intermediate layer 89 and the carbon protective film 90 by plasma CVD.
It comprises a microwave power supply 136, a magnet 138, a microwave introduction tube 140, a coaxial converter 142, a dielectric plate 144, a radial antenna 146, and the like.

The DC discharge generates a plasma by applying a negative DC voltage between the substrate and the electrode. The DC power source used for the DC discharge is about 1 to 10 kW, and a DC power source having a sufficient output necessary for forming the carbon protective film 90 may be appropriately selected. Further, a DC power supply pulse-modulated at 2 kHz to 20 kHz can be suitably used in terms of arc prevention and the like. The high-frequency discharge is performed by applying a high-frequency voltage to the electrodes via a matching box.
Generates plasma. At this time, 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 for performing high-frequency discharge, industrial 1
3.56 MHz or higher, for example,
1 to 10 kW, preferably 1 kW at triple frequency
What is necessary is to appropriately select an output having a necessary and sufficient output for the intended film formation in the output range of about 5 kW. Also, a pulse-modulated high-frequency power supply can be used. DC arc discharge uses a hot cathode to generate a plasma. As the hot cathode, tungsten, lanthanum boride (LaB ₆ ), or the like can be used. DC arc discharge using a hollow cathode can also be used. As a DC power supply used for DC arc discharge, about 1 kW to 10 kW,
In the range of about 10 to 150 A, a material having a sufficient and necessary output for the intended film formation may be appropriately selected.

The microwave ECR discharge is performed by the microwave and E
A plasma is generated by the CR magnetic field,
As described above, the illustrated CVD apparatus generates plasma by the microwave discharge. Microwave power supply 1
As 36, an industrial grade of 2.45 GHz, 1 kW to 3
In the range of about kW, a material having a sufficient output that is necessary for forming the carbon protective film 90 or the like may be appropriately selected.
For generating the ECR magnetic field, a permanent magnet or an electromagnet capable of forming a desired magnetic field may be appropriately used. In the illustrated example, a Sm-Co magnet is used as the magnet 138. For example, when a microwave of 2.45 GHz is used, E
Since the CR magnetic field is 875 G (Gauss), a magnet having a magnetic field of 500 G to 2000 G in the plasma generation region may be used. The introduction of microwaves into the vacuum chamber 102 is performed using a microwave introduction tube 140, a coaxial converter 142, a dielectric plate 144, and the like. Since the state of formation of the magnetic field and the introduction path of the microwave affect the distribution of the thickness of the carbon protective film 90 and the like, it is preferable to optimize the thickness so as to be uniform.

The substrate holder 114 holds the thermal head 66
Is fixed. Here, the film forming apparatus 10 of the illustrated example
0 has three film forming means, and the substrate holder 114 has each film forming means, that is, the sputtering means 10.
6 and 108, and a glaze serving as a substrate can be opposed to plasma generation means 110 for performing plasma CVD.
The substrate holder 114 is held by a rotating substrate 150 that swings. What is necessary is just to select suitably according to the size of a board | substrate, etc.
Further, a heater may be provided on the upper surface of the substrate holder 114 so that sputtering is performed while heating. There is no particular limitation on the distance between the substrate and the target material 120 or the radial antenna 146.
The distance at which the film thickness distribution is uniform may be selected and set within a range of about 200 mm.

Here, as described above, prior to the formation of the intermediate layer 89, it is preferable that the surface of the lower protective film 88 after the lapping process is etched with plasma. 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. To this end, a bias power supply 112 for applying a high-frequency voltage to the substrate holder 114 is connected to the film forming apparatus 100. The bias power supply 112 applies a high-frequency voltage to a substrate via a matching box, and is used for industrial purposes.
It may be appropriately selected from those of about 1 kW to 5 kW at 3.56 MHz.

The etching strength may be determined by using a bias voltage applied to the substrate as a guide.
Optimization may be appropriately performed in the range of 500 V. Note that such etching may be performed prior to the formation of the carbon protective film 90 on the intermediate layer 89. In the case of plasma CVD, it is preferable to use a self-bias voltage of a high frequency voltage. Self bias voltage is negative 100V
~ 500V.

As a preferred embodiment, the film forming apparatus 100 shown in the drawing has three film forming means, namely, sputtering means 106 and 108 and a plasma generating means 110 for performing plasma CVD. 66 is not limited to forming the intermediate layer 89 and the carbon protective film 90 using the film forming apparatus 100, and a normal film forming apparatus having only one sputtering means or plasma generating means may be used. Of course.
Further, the sputtering means and the plasma generating means
Depending on the intended layer configuration of the thermal head, such as a film forming apparatus having two or three sputtering means or only two or three plasma generating means,
Various types of film forming apparatuses can be used. The specifications of each part of the film forming apparatus may be in accordance with the above-described example.

Although the thermal head of the present invention has been described in detail above, the present invention is not limited to the above-described example, and various improvements and changes can be made without departing from the gist of the present invention. Of course it is good.

[0064]

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

[Example 1] KGT-260-12MPH8 manufactured by Kyocera Corporation was used as a base thermal head. In this thermal head, a silicon nitride film (Si ₃ N ₄ ) having a thickness of 11 μm and an Ra value of 3 nm is formed as a protective film on the glaze surface. Therefore, in this embodiment, the silicon nitride film is the lower protective film 88, and the following intermediate layer 89 is formed on the lower protective film 88. On the intermediate layer 89, the carbon protective film 90 is formed as the upper protective film. It is formed.

The intermediate layer 89 and the carbon protective film 90 were formed on such a thermal head by using the film forming apparatus 100 shown in FIG. The details of the film forming apparatus 100 are as follows.

A. Vacuum chamber 102 SUS3 having one vacuum pump as a vacuum pump 116, each of a rotary pump having a pumping speed of 1500 L (liter) / min, a mechanical booster pump having a pump speed of 12,000 L / min, and a turbo pump having a pump speed of 3000 L / sec.
A vacuum chamber 102 having a capacity of 0.5 m ³ made of 04 was used. An orifice valve is arranged in the suction part of the turbo pump so that the opening degree can be adjusted from 10 to 100%.

B. Gas introduction unit 104 Using a mass flow controller having a maximum flow rate of 100 to 500 [sccm] and a stainless steel pipe having a diameter of 6 mm, two gas introduction tubes 104 for a plasma generation gas and a reaction gas.
a and 104b were formed. The joint between the stainless steel pipe and the vacuum chamber 102 was vacuum-sealed with an O-ring. Note that, when the intermediate layer 89 and the carbon protective film 90 described below were formed, argon gas was used as a gas for plasma generation.

C. First Sputtering Means 106 and Second Sputtering Means 108 As the permanent magnets 118a and 126a, rectangular cathodes 118 and 126 having a width of 600 mm and a height of 200 mm in which Sm-Co magnets were disposed were used. As the backing plates 132 and 134, oxygen-free copper processed into a rectangular shape was used, and the cathodes 118 and 126 were adhered to the cathodes 118 and 126 using In-based solder. Also, the cathodes 118 and 12
6 is cooled with water, so that the magnets 118a and
6a, the cathodes 118 and 126, and the back surfaces of the backing plates 132 and 134 were cooled. Also,
High frequency power supply 12 used in first sputtering means 106
As No. 4, a high-frequency power supply with a maximum potential of 5 kW and a negative potential was used, and as a DC power supply 130 used in the second sputtering means 108, a DC power supply with a maximum potential of 8 kW and a negative potential was used. Note that this DC power supply is configured so that it can be modulated in a pulse form in the range of 2 kHz to 10 kHz.

D. Plasma generating means 110 A microwave power supply 136 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 102 by the microwave introduction tube 140, converted by the coaxial converter 142, and then introduced into the radial antenna 146 in the vacuum chamber 102. The plasma generator has a width of 60
A rectangular shape of 0 mm × 200 mm in height was used. Furthermore, E
For the CR magnetic field, a plurality of Sm-Co magnets were used as the magnets 138,
It was formed by arranging it according to the shape of the dielectric plate 144.

E. Substrate holder 114 By the action of rotating substrate 150, the held substrate (that is, glaze 82 of thermal head 66) is held by first sputtering means 106 and second sputtering means 10
8 and the radial antenna 146 of the plasma generating means 110 and holding it. Also, regardless of the orientation,
Substrate and target material 120 or radial antenna 14
6 has a configuration that can be adjusted between 50 mm and 150 mm. When the intermediate layer 89 and the carbon protective film 90 are formed by sputtering as described below, the distance between the substrate and the target material 120 is 100 mm, and the plasma C
When forming the carbon protective film 90 by VD, the distance between the substrate and the radial antenna 146 was set to 150 mm. Further, the holding portion of the thermal head was set at a floating potential so that a high frequency voltage for etching could be applied. Furthermore,
A heater is provided on the surface of the substrate holder 114 so that film formation can be performed while heating.

F. Bias power supply 112 A high frequency power supply was connected to the substrate holder 114 via a matching box. The high frequency power supply has a frequency of 13.56M
At Hz, the maximum power is 3 kW. The high-frequency power supply is configured to be capable of adjusting a high-frequency output in a negative range of 100 V to 500 V by monitoring a self-bias voltage. In this apparatus, the bias power supply 112 also serves as a substrate etching unit.

<Production of Thermal Head> In such a film forming apparatus 100, the glaze 8
The thermal head 66 was fixed to the substrate holder 114 in the vacuum chamber 102 in a state where No. 2 was opposed to the holding position of the target material 120 arranged in the first sputtering means 106. Note that masking was performed in advance on portions other than the portion where the intermediate layer 89 of the thermal head was formed (that is, other than glaze). After fixing the thermal head, evacuation was performed until the pressure in the vacuum chamber 102 became 5 × 10 ⁻⁶ Torr. While continuing the evacuation, the gas introduction unit 1
04, an argon gas was introduced, and an orifice valve installed in a turbo pump was
The internal pressure was adjusted to be 5.0 × 10 ⁻³ Torr.
Next, a high-frequency voltage was applied to the substrate, and the lower protective film (silicon nitride film) was etched at a self-bias voltage of −300 V for 10 minutes.

After completion of the etching, a single crystal Si target is used as the target material 120 in the first sputtering means 1.
06, and the sintered graphite material is fixed to the backing plate 134 of the second sputtering means 108 (attached with In-based solder), and then the inside of the vacuum chamber 102 is evacuated again to reduce the pressure. The argon gas flow rate and the orifice valve were adjusted so as to be 5 × 10 ⁻³ Torr, and the DC power of 0.5 kW was applied to the target material 120 with the shutter 122 closed.
Was applied for 5 minutes. Next, while maintaining the pressure in the vacuum chamber 102, the shutter 1
22 was opened, and sputtering was performed until the film thickness became 0.2 μm, thereby forming an intermediate layer 89 having a thickness of 0.2 μm. The film thickness of the intermediate layer 89 was determined in advance by calculating the film forming speed, calculating the film forming time to obtain a predetermined film thickness, and controlling the film forming time.

Next, the glaze is directed to the target 120 (sintered graphite material) arranged on the second sputtering means 108 by the rotating substrate 150 so that the pressure in the vacuum chamber 102 becomes 5 × 10 ^-3 Torr and argon gas is supplied. Adjust the flow rate and the orifice valve,
28 with the DC power of 0.
5 kW was applied for 5 minutes. Next, the vacuum chamber 102
While maintaining the internal pressure, the shutter 128 was opened with a DC power of 5 kW, and sputtering was performed until the film thickness became 2 μm, thereby producing a thermal head having a carbon protective film 90 having a thickness of 2 μm as an upper protective film. The film thickness of the carbon protective film 90 was controlled in advance by calculating a film forming speed, calculating a film forming time to obtain a predetermined film thickness, and controlling the film forming time.

Further, a total of four types of thermal heads were formed in exactly the same manner except that the intermediate layer 89 was formed using Ti, Mo, and W targets as targets disposed on the backing plate 132 of the first sputtering means 106. Was prepared.

<Evaluation of Performance> Using the four kinds of thermal heads of the present invention and a heat-sensitive material (film CR-AT for dry image recording, manufactured by Fuji Photo Film Co., Ltd.), the heat-sensitive recording apparatus shown in FIG. A thermal recording test was performed on 5000 sheets in size. As a result, none of the four types of thermal heads causes cracking or peeling of the carbon protective film 90, hardly recognizes abrasion, shows good durability, and has high image quality without density unevenness. Images could be recorded stably.

[Embodiment 2] Prior to the etching of the lower protective film 88, the lower protective film 88 of the thermal head was changed to # 800.
0, except that the surface of the lower protective film 88 was roughened until the Ra value became 0.2 μm by passing the wrapping sheet in contact with the wrapping sheet (B4 size). In the same manner as in Example 1, a thermal head was manufactured. Polishing with the wrapping sheet was performed by passing ten wrapping sheets while the base thermal head on which the lower protective film 88 was formed was attached to the thermal recording apparatus. The surface roughness (Ra value) was measured by using a stylus-type roughness tester (manufactured by Tencor; P-1) without cutting off the surface shape of the lower protective film 88 at a plurality of locations. Was obtained by calculating an average value of Ra values at a plurality of locations obtained by two-dimensionally measuring Ra. The thermal head thus obtained was evaluated for performance in the same manner as in Example 1. As a result, good results were obtained, which were equal to or better than Example 1.

[Example 3] Production and performance evaluation of a thermal head in the same manner as in Example 2, except that the roughness of the lower protective film 88 of the thermal head due to the passage of the wrapping sheet was changed to an Ra value of 0.1 µm. Was done. The thermal head thus obtained also showed good results equal to or better than those of Example 1.

Example 4 A wrapping sheet # 1
A thermal head was manufactured and its performance was evaluated in the same manner as in Example 2, except that the lower protective film 88 of the thermal head due to the passing of the wrapping sheet was made to have a roughness of 0.005 μm. went. In the thermal head thus obtained, Example 1 was also used.
The results were as good as or better.

[Embodiment 5] The entire thermal head substrate was 1
The production and performance evaluation of the thermal head were performed in the same manner as in Example 1 except that the carbon protective film 90 was formed on the surface of the intermediate layer 89 while heating to 00 ° C. to 250 ° C. Specifically, a heater was provided on the upper surface of the substrate holder 114, and the carbon protective film 90 was formed while the substrate was heated by placing the substrate thereon. The thermal head thus obtained also showed good results equal to or better than those of Example 1.

Example 6 A thermal head was formed in the same manner as in Example 1 except that the surface of the intermediate layer 89 was heated to 200 ° C. to 450 ° C. to form the carbon protective film 90 by energizing the thermal head. The head was made and its performance was evaluated. Specifically, while the strobe of the driver IC of the thermal head is in the ON state, a constant direct current is applied to the common side, so that the thermal head 66 is energized to generate heat, and the surface of the intermediate layer 89 is heated to a constant temperature. Then, a carbon protective film 90 was formed. The thermal head thus obtained also showed good results equal to or better than those of Example 1.

[Comparative Example 1] Preparation and performance of a thermal head in the same manner as in Example 1 except that the carbon protective film 90 was formed directly on the lower protective film 88 without forming the intermediate layer 89. An evaluation was performed. As a result, the cracking or peeling of the carbon protective film 90 occurred before the recording of 5000 sheets was completed.

[Embodiment 7] Second sputtering means 10
An intermediate layer 89 having a thickness of 0.2 μm was formed on the surface of the lower protective film 88 of the thermal head (the same thing as in Example 1), except that no target was disposed on 8. Note that the target material 120 disposed in the first sputtering means 106 is a Si single crystal target.

Next, the glaze 66 is formed by the rotating substrate 150 on the radial antenna 146 of the plasma generating means 110.
Pressure in the vacuum chamber 102 is set to 5 × 10 ⁻⁶ Torr
Was adjusted. While continuing the evacuation, the gas introduction pipe 10
Methane gas was introduced from 4a, and the pressure in the vacuum chamber 102 was adjusted to 5.0 × 10 ⁻³ Torr by an orifice valve installed in a turbo pump. Next, the microwave power supply 136 is driven to introduce microwaves into the vacuum chamber 102 to perform plasma CVD.
A thermal head in which a carbon protective film 90 having a thickness of 1 μm was formed on the intermediate layer 89 as an upper protective film was manufactured.
The film thickness of the carbon protective film 90 was controlled in advance by calculating a film forming speed, calculating a film forming time to obtain a predetermined film thickness, and controlling the film forming time.

Further, a total of three types of thermal heads were manufactured in exactly the same manner except that the intermediate layer 89 was formed using Ti and Mo targets as targets to be disposed in the first sputtering means 106.

<Evaluation of Performance> Using the three kinds of thermal heads and the heat-sensitive material, the same performance evaluation as in Example 1 was performed by the heat-sensitive recording apparatus shown in FIG. As a result, none of the thermal heads caused cracking or peeling of the carbon protective film 90, and hardly any wear was recognized.

[Embodiment 8] Prior to the etching of the lower protective film 88, the lower protective film 88 of the thermal head was changed to # 800.
The wrapping sheet is passed through the sheet in a state where the wrapping sheet is in contact with the wrapping sheet having a Ra value of 0.2 μm.
The production and performance evaluation of the thermal head were carried out in the same manner as in Example 7, except that the surface of the lower protective film was roughened until the temperature became. The paper passing method is the same as in the second embodiment. The thermal head thus obtained also showed good results equal to or better than those of Example 7.

Example 9 The production and performance evaluation of a thermal head were performed in the same manner as in Example 7, except that the roughness of the lower protective film 88 of the thermal head due to the passage of the wrapping sheet was changed to an Ra value of 0.1 μm. Was done. The thermal head thus obtained also showed good results equal to or better than those of Example 7.

[Embodiment 10] As wrapping sheet #
The production and performance evaluation of the thermal head were performed in the same manner as in Example 7 except that the roughness of the lower protective film 88 of the thermal head due to the passing of the wrapping sheet was changed to 0.005 μm in Ra value. went. The thermal head thus obtained also showed good results equal to or better than those of Example 7.

Example 11 A thermal head was manufactured in the same manner as in Example 7, except that the carbon protective film 90 was formed on the surface of the intermediate layer 89 while heating the entire thermal head substrate to 100 ° C. to 250 ° C. Creation and performance evaluation were performed. Specifically, a heater is provided on the upper surface of the substrate holder 138, and the substrate is placed on the heater, thereby heating the entire substrate.
A carbon protective film 90 was formed. The thermal head thus obtained also showed good results equal to or better than those of Example 7.

Example 12 A thermal head was formed in the same manner as in Example 7, except that the carbon protective film 90 was formed while the intermediate layer 89 was heated to 200 ° C. to 450 ° C. by energizing the thermal head. The head was made and its performance was evaluated. Specifically, while the strobe of the driver IC of the thermal head is in the ON state, a constant direct current is applied to the common side, so that the thermal head 66 is energized to generate heat, and the surface of the intermediate layer 89 is heated to a constant temperature. Then, a carbon protective film 90 was formed. The thermal head thus obtained also showed good results equal to or better than those of Example 7.

Comparative Example 2 Preparation and performance of a thermal head were performed in the same manner as in Example 7, except that the carbon protective film 90 was formed directly on the lower protective film 88 without forming the intermediate layer 89. An evaluation was performed. As a result, the cracking or peeling of the carbon protective film 90 occurred before the recording of 5000 sheets was completed. From the above results, the effect of the present invention is clear.

[0094]

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

[Brief description of the 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 of an example of a film forming apparatus used for manufacturing a thermal head according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 (Thermal) recording device 14 Loading part 16 Supplying and conveying means 20 Recording part 22 Ejection part 24 Magazine 66 Thermal head 80 Substrate 82 Glaze layer 84 Heating (resistance) body 86 Electrode 88 Lower protective film 89 Intermediate layer 90 Carbon protective film 100 Film device 102 Vacuum chamber 104 Gas introduction unit 106 First sputtering unit 108 Second sputtering unit 110 Plasma generation unit 112 Bias power supply 114 Substrate holder 116 Vacuum exhaust unit 118, 126 Cathode 120 Target material 122, 128 Shutter 124 High frequency 130 DC power supply 132 , 134 Backing plate 136 Microwave power supply 138 Magnet 140 Microwave introduction tube 142 Coaxial converter 144 Dielectric plate 146 Radial antenna A Thermal material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-132628 (JP, A) JP-A-1-171646 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/335

Claims (5)

(57) [Claims] 1. A protective film for protecting a heating element, comprising: a lower protective film formed on the heating element side and comprising at least one layer mainly composed of ceramic; and a protective film formed on the lower protective film and comprising at least one layer. A thermal protective head comprising: an intermediate protective film comprising: an upper protective film comprising carbon as a main component; 2. The intermediate layer protective film according to claim 1, wherein the intermediate layer protective film is a 4A group metal, 5A
2. The thermal head according to claim 1, wherein at least one selected from the group consisting of a Group III metal, a Group 6A metal, Si and Ge is used as a main component. 3. The intermediate layer protective film has a thickness of 0.05 μm or less.
2 μm, and the thickness of the upper protective film is 0.5 μm to 5 μm.
The thermal head according to claim 1, wherein the thermal head is μm. 4. A lapping process and an etching process are performed on the surface of the lower protective film so that the surface roughness Ra of the surface is 1 nm to 0.4 μm, and thereafter, the intermediate protective film is formed. The thermal head according to any one of claims 1 to 3, which is formed. 5. The thermal head according to claim 1, wherein the lower protective film is made of at least one of a nitride and a carbide.