JP2004351797A - Thermal head, its manufacturing process, and thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal head which can be applied rigidly with a protective film containing hydrogen, and to provide its manufacturing process and a thermal printer. <P>SOLUTION: A thermal head comprises a heating element 3, a pair of electrodes 4 being connected with the heating element 3, and a protective film 5 covering the heating element 3 and the pair of electrodes 4 wherein the protective film 5 principally comprises an inorganic material containing hydrogen. Hydrogen content in the lower region of the protective film 5 is set at nil or set lower than that of other regions. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４８】
この表１によれば、水素分圧が１０％以下であるサンプルＮｏ．１，２では良好な結果が得られている。一方、水素分圧が１５％以上であるサンプルＮｏ．３〜Ｎｏ．６では保護膜が剥がれ易くなっていることがわかる。
【００４９】
（第２実験）
次に、下部領域の水素含有量を０原子％、１０原子％に、上部領域の水素含有量を３０原子％に設定した状態で下部領域の厚みを少しずつ異ならせた保護膜（サンプルＮｏ．８〜１３）と、全体の水素含有量を３０原子％に略揃えた保護膜（サンプルＮｏ．７）とを準備し、かかる保護膜の密着強度を第１実験と同様の方法で測定した。尚、保護膜の厚みは３μｍとした。
【００５０】
【表２】

【００５１】
表２によれば、下部領域を０．０１μｍ〜０．６μｍに設定したサンプルＮｏ．８〜１３においては５５ｋｇｆ以上の比較的大きな荷重まで保護膜を被着させることができた。一方、保護膜全体の水素含有量が略均一なサンプルＮｏ．７では小さな荷重で保護膜が剥がれた。
【００５２】
従って、保護膜を形成する際、下部領域の厚みを０．０１μｍ〜０．６μｍとし、且つ初期段階の水素ガスの使用量を水素分圧で０％〜１０％とすれば保護膜を良好に基板に対して密着させておくことができる。
【００５３】
【発明の効果】
本発明によれば、水素を含んだガスを使用して保護膜を形成する際、水素使用量を保護膜形成の初期段階において皆無となすか、もしくは初期段階以降の段階よりも初期段階で小さくすることにより、保護膜の下地に多量の水素が付着することを有効に防止でき、水素を含んだ保護膜を強固に被着させておくことが可能なサーマルヘッドを得ることができる。従って、保護膜に対して記録媒体を強く搬送させたとしても、保護膜に剥離が生じるのを有効に防止でき、信頼性の高いサーマルプリンタが実現される。
【００５４】
また保護膜中の炭素同士の結合がｓｐ^２混成軌道にかかる共有結合を主成分とする場合、保護膜中に含まれる水素によって保護膜中に多数存在する自由電子が良好に捕獲されるため、保護膜の絶縁性を効果的に高めることができるという利点がある。
【図面の簡単な説明】
【図１】本発明の一実施形態に係るサーマルヘッドの断面図である。
【図２】図１の保護膜を製造する際に使用されるスパッタリング装置の概略構成図である。
【図３】図１のサーマルヘッドを組み込んで構成されたサーマルプリンタの概略構成図である。
【図４】本発明の他の実施形態に係るサーマルヘッドの断面図である。
【符号の説明】
１・・・基板
２，２ａ・・・グレーズ層
３・・・発熱素子
４・・・電極
５・・・保護膜
１０・・・プラテンローラ（搬送手段）
１１ａ，１１ｂ，１１ｃ，１１ｄ・・・搬送ローラ（搬送手段）
Ｔ・・・サーマルヘッド
Ｃ・・・駆動手段[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermal head and a thermal printer for forming a print using heat generated by a heating element.
[0002]
[Prior art]
Conventionally, a thermal head incorporated as a printer mechanism such as a word processor is provided with a plurality of heating elements and a pair of electrodes on an insulating substrate made of alumina ceramics or the like via a glass glaze layer to protect these heating elements and the pair of electrodes. The thermal head has a structure covered with a film, and such a thermal head applies predetermined power to the heating elements via electrodes based on image data from the outside, and selectively causes the heating elements to generate Joule heat individually. At the same time, the generated heat is conducted to a recording medium such as thermal paper, and a predetermined print is formed on the recording medium to function as a thermal head.
[0003]
The protective film is for protecting the heating element and the like from abrasion due to sliding contact of the recording medium and corrosion due to contact with moisture or the like contained in the atmosphere. For example, a SiC-based, SiON-based, or SiO-based inorganic material is used. Is formed.
[0004]
By the way, the protective film of the thermal head is required to have sufficient insulating properties to prevent a short circuit between a pair of electrodes, and to have appropriate conductivity to effectively prevent dielectric breakdown of the protective film due to static electricity. In order to satisfy such characteristics, a method is known in which hydrogen is contained in a protective film and the resistance value of the protective film is finely adjusted by adjusting the content of hydrogen (Patent Document 1). reference).
[0005]
In Patent Document 1, the protective film is formed by employing a conventionally known reactive sputtering. Specifically, a target material formed by sintering the constituent material of the protective film and a substrate are placed in a chamber. Hydrogen gas is introduced as a reaction gas into the chamber in the arranged state, and hydrogen is contained in the protective film by using hydrogen between the target material and the substrate.
[0006]
[Patent Document 1]
JP 2000-153630 A
[Problems to be solved by the invention]
However, in the conventional method for manufacturing a thermal head including Patent Document 1, since hydrogen is used as a reactive gas from the initial stage of reactive sputtering, a large amount of hydrogen adheres to the underlayer of the protective film. In this state, the inorganic material serving as the material of the protective film is sequentially deposited. If a large amount of hydrogen exists under the protective film, the adhesion of the protective film is significantly reduced, and the protective film may be easily peeled.
[0008]
The present invention has been devised in view of the above drawbacks, and has as its object to provide a thermal head capable of firmly attaching a protective film containing hydrogen, a method of manufacturing the same, and a thermal printer. It is in.
[0009]
[Means for Solving the Problems]
The thermal head according to the present invention includes a heating element, a pair of electrodes connected to the heating element, and a protective film covering the heating element and the pair of electrodes, and the protective film mainly includes an inorganic material containing hydrogen. In the thermal head as a component, the hydrogen content in the lower region of the protective film is set to be smaller than in other regions.
[0010]
Further, in the thermal head according to the present invention, the protective film contains carbon and silicon as main components.
[0011]
Further, the thermal head according to the present invention is characterized in that the carbon-carbon bonds are mainly composed of covalent bonds related to sp ² hybrid orbitals.
[0012]
Still further, the thermal head according to the present invention is characterized in that an intermediate layer made of an insulating material is interposed between the protective film and the heating element.
[0013]
On the other hand, a method of manufacturing a thermal head according to the present invention includes a heating element, a pair of electrodes connected to the heating element, a protective film covering the heating element and the pair of electrodes, and formed of a material containing hydrogen. A method for manufacturing the thermal head, comprising the steps of: using a gas containing hydrogen in forming the protective film, and reducing the amount of hydrogen used in the initial stage from the initial stage of forming the protective film. It is characterized by having.
[0014]
In the method for manufacturing a thermal head according to the present invention, the protective film is formed by reactive sputtering using the gas containing hydrogen as a reactive gas.
[0015]
Further, a thermal printer according to the present invention includes the above-described thermal head, transport means for transporting a recording medium on the heating element, and drive means for driving the thermal head.
[0016]
According to the present invention, when forming a protective film using a gas containing hydrogen, by reducing the amount of hydrogen used in the initial stage from the initial stage of the protective film formation after the initial stage, a large amount of hydrogen under the protective film. Hydrogen can be effectively prevented from adhering, and a thermal head can be obtained in which a protective film containing hydrogen can be firmly adhered. Therefore, even if the recording medium is strongly conveyed to the protective film, it is possible to effectively prevent the protective film from peeling off, and a highly reliable thermal printer is realized.
[0017]
Further, when the bond between carbon atoms in the protective film is mainly composed of a covalent bond involving sp ² hybrid orbitals, a large number of free electrons present in the protective film are well captured by hydrogen contained in the protective film. There is an advantage that the insulating property of the protective film can be effectively increased.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an embodiment of the thermal head of the present invention. The thermal head shown in FIG. 1 has a structure in which a glaze layer 2, a heating element 3, a pair of electrodes 4 and a protective film 5 are provided on a substrate 1. have.
[0019]
The substrate 1 is made of various materials such as an electrically insulating material such as alumina ceramics and glass and a semiconductor material such as single crystal silicon having an insulating film formed on the surface. It functions as a supporting base material for supporting the electrodes 4, the protective film 5, and the like.
[0020]
When the substrate 1 is made of alumina ceramics, first, an appropriate organic solvent and a solvent are added to a ceramic raw material powder such as alumina, silica, magnesia or the like to form a slurry, which is then formed into a slurry-like shape. A ceramic green sheet is formed by employing a roll method or the like, and thereafter, the ceramic green sheet is punched into a predetermined shape and fired at a high temperature.
[0021]
On the upper surface of the substrate 1, a glaze layer 2 is formed with a thickness of 20 μm to 60 μm.
[0022]
The glaze layer 2 is formed of a low thermal conductive material such as glass or polyimide resin, and accumulates heat therein so that the heat generated by the heating element 3 becomes an appropriate temperature. Is maintained.
[0023]
When the glaze layer 2 is formed of glass, a conventionally well-known screen printing method is used on the entire upper surface or a predetermined region of a glass paste obtained by adding and mixing an appropriate organic solvent and a solvent to glass powder. Is printed and applied to a predetermined thickness, and then baked at a high temperature (about 900 ° C.) to be formed on the upper surface of the substrate 1.
[0024]
On the upper surface of the glaze layer 2, a plurality of heating elements 3 are linearly attached and arranged at a density of, for example, 300 dpi (dot per inch), and a pair of electrodes 4 are provided at both ends of each heating element 3. It is electrically connected.
[0025]
The heating element 3 is made of an electric resistance material such as TaSiO, TaSiNO, TiSiO, TiSiCO, NbSiO, TiSiNi, and has a predetermined electric resistivity. Then, Joule heat is generated, and the temperature reaches a predetermined temperature required for forming a print on a recording medium, for example, a temperature of 250 ° C. to 400 ° C.
[0026]
On the other hand, a pair of electrodes 4 connected to both ends of the heating element 3 are made of a metal such as aluminum (Al) or copper (Cu), and supply a predetermined electric power necessary for causing the heating element 3 to generate Joule heat. It acts to apply.
[0027]
The plurality of heating elements 3 and the pair of electrodes 4 are formed by a conventionally known thin-film method, specifically, a sputtering method, a photolithography technique, an etching technique, or the like. It is formed by applying a predetermined thickness and a predetermined pattern.
[0028]
A protective film 5 is attached on the upper surfaces of the heating element 3 and the pair of electrodes 4, and covers the heating element 3 and the pair of electrodes 4 with the protective film 5.
[0029]
The protective film 5 is for protecting the heating element 3 and the pair of electrodes 4 from corrosion due to contact with moisture or the like contained in the atmosphere and wear due to sliding contact of the recording medium, and is made of SiC, SiN, or SiO. And the like, and contains 5 to 45 atomic% of hydrogen therein.
[0030]
Further, the protective film 5 is set so that the hydrogen content in the lower region thereof (the region of 0.01 μm to 0.6 μm from the bottom surface of the protective film 5) is smaller than that of the other regions (the lower region includes Specifically, the hydrogen content in the lower region is set to 0 to 10 atomic%, and the hydrogen content in the other regions is set to 5 to 45 atomic%. (However, the hydrogen content is lower in the lower region). Therefore, the adhesion of the protective film 5 to the base can be made strong.
[0031]
As a method for forming such a protective film 5, a thin film forming technique using a gas containing hydrogen, such as a sputtering method or a CVD method, can be considered.
[0032]
For example, when the protective film 5 containing SiC as a main component is formed by reactive sputtering, first, as shown in FIG. 3, a chamber of a sputtering device is formed of a sintered body in which carbon (C) and silicon (Si) are mixed. The target material and the substrate 1 on which the heating elements 3 and the electrodes 4 are attached are respectively arranged.
[0033]
Next, a predetermined electric power is applied between the target material and the substrate 1 while introducing an argon gas and a hydrogen gas into the chamber, and the constituent material of the target material is sputtered with argon to form a part of the target material. Is adhered to the substrate 1. At this time, the usage amount of the hydrogen gas is reduced in the initial stage of forming the protective film 5 (stage in which the constituent material of the target material is deposited on the substrate 1 at 0.01 μm to 0.6 μm), and is increased in the subsequent stages. This is very important. For example, the amount of hydrogen gas used is set to a partial pressure of hydrogen of 0% to 10% with respect to the whole introduced gas in the initial stage of formation of the protective film, and to a partial pressure of hydrogen of 10% to 50% in the stages after the initial stage.
[0034]
By controlling the amount of hydrogen gas used in this manner, a large amount of hydrogen adheres to the base of the protective film 5 (the heating element 3 and the pair of electrodes 4 in this embodiment) when forming the protective film 5. Therefore, the protective film 5 containing hydrogen can be firmly adhered to the base.
[0035]
Thus, the above-described thermal head applies predetermined power between the pair of electrodes 4 based on image data from the outside, and selectively causes the heating elements 3 to individually generate Joule heat. The recording medium functions as a thermal head by forming a predetermined print on the recording medium.
[0036]
As shown in FIG. 3, a thermal printer incorporating the above-described thermal head includes a driving unit C for driving the thermal head T and a transport unit for transporting the recording medium onto the heating element 3 of the thermal head T. The platen roller 10 and the transport rollers 11a, 11b, 11c, 11d are provided.
[0037]
The driving means C includes a driver IC in which shift registers, latches, switching transistors, and the like are integrated at high density, and a control circuit that supplies control signals such as strobe signals and latch signals to the driver IC. By switching on / off the switching transistor in the driver IC based on the control signal, the heat generation of the heating element 3 is controlled.
[0038]
On the other hand, the platen roller 10 as a conveying means is a columnar member in which butadiene rubber or the like is wound around a shaft core made of metal such as SUS to a thickness of about 3 mm to 15 mm. The recording medium is conveyed in a direction perpendicular to the arrangement of the heating elements 3 (the direction of the arrow in the figure) while pressing the recording medium against the heating elements 3.
[0039]
The transport rollers 11a, 11b, 11c, and 11d have outer peripheral portions formed of metal, rubber, or the like, and are disposed separately from the thermal head T on the upstream side and the downstream side in the recording medium transport direction. The transport of the recording medium is supported by the transport rollers 11a, 11b, 11c, 11d and the platen roller 10 described above.
[0040]
At the same time, a large number of heating elements 3 are selectively caused to generate Joule heat in accordance with the driving of the driving means C, and the heat is transmitted to the recording medium, whereby a predetermined print is formed.
[0041]
Note that the present invention is not limited to the above-described embodiment, and various changes, improvements, and the like can be made without departing from the gist of the present invention.
[0042]
For example, in the above-described embodiment, the protective film 5 is directly deposited on the heating element 3 and the pair of electrodes 4, but instead, a SiON-based material may be interposed between the protective film 5 and the heating element 3 and the electrode 4. Needless to say, the present invention can be applied even if an intermediate film made of an inorganic material such as SiN, SiO, or SiC is interposed.
[0043]
In the above-described embodiment, the glaze layer 2 is formed to have a substantially constant thickness over the entire upper surface of the substrate 1. However, as shown in FIG. May be partially formed on the upper surface of the substrate 1, and it is needless to say that the present invention can be applied to a glaze layer having another shape.
[0044]
Further, in the above-described embodiment, when the bonds between carbons in the protective film 5 are mainly composed of covalent bonds related to sp ² hybrid orbitals, the free electrons which are present in the protective film 5 in large numbers due to the hydrogen contained in the protective film 5. Is advantageously captured, so that the insulating property of the protective film can be effectively increased.
[0045]
[Experimental example]
Next, the operation and effect of the present invention will be described based on experimental examples.
[0046]
(First experiment)
In the first experiment, the adhesion of the protective film to the substrate when the protective film was formed by reactive sputtering was measured. Carbon (C) and silicon (Si) were used as target materials at a ratio of 80:20. Six protective films (Sample Nos. 1 to 6) were formed using the mixed sintered body, and using argon gas and hydrogen gas as the gases introduced into the chamber, while gradually changing the ratio of the hydrogen gas. . The thickness of the protective film was set to 3 μm, and the adhesion strength of the protective film was measured using a scratch tester (full scale: 980 mN). Specifically, while the diamond needle (indenter needle) constituting the scratch tester is pressed against the protective film, the diamond needle is moved while vibrating the diamond needle at a predetermined frequency (30 Hz), and the protective film is The load for peeling was measured. Table 1 shows the results of the above experiments.
[0047]
[Table 1]

[0048]
According to Table 1, Sample No. 1 having a hydrogen partial pressure of 10% or less was used. In Examples 1 and 2, good results were obtained. On the other hand, in Sample No. 1 having a hydrogen partial pressure of 15% or more. 3-No. 6, it can be seen that the protective film was easily peeled off.
[0049]
(Second experiment)
Next, a protective film (Sample No. 1) in which the thickness of the lower region was slightly changed while the hydrogen content of the lower region was set to 0 atomic% and 10 atomic% and the hydrogen content of the upper region was set to 30 atomic%. 8 to 13) and a protective film (Sample No. 7) having a total hydrogen content substantially equal to 30 atomic%, and the adhesion strength of the protective film was measured by the same method as in the first experiment. Note that the thickness of the protective film was 3 μm.
[0050]
[Table 2]

[0051]
According to Table 2, the sample No. in which the lower region was set to 0.01 μm to 0.6 μm. In Nos. 8 to 13, the protective film could be applied to a relatively large load of 55 kgf or more. On the other hand, Sample No. 1 in which the hydrogen content of the entire protective film was substantially uniform. In No. 7, the protective film was peeled off with a small load.
[0052]
Therefore, when forming the protective film, if the thickness of the lower region is set to 0.01 μm to 0.6 μm and the amount of hydrogen gas used in the initial stage is set to 0% to 10% in terms of hydrogen partial pressure, the protective film can be formed well. It can be in close contact with the substrate.
[0053]
【The invention's effect】
According to the present invention, when forming a protective film using a gas containing hydrogen, the amount of hydrogen used in the initial stage of the protective film formation is negligible, or is smaller in the initial stage than the subsequent stages. By doing so, it is possible to effectively prevent a large amount of hydrogen from adhering to the underlayer of the protective film, and it is possible to obtain a thermal head capable of firmly attaching the protective film containing hydrogen. Therefore, even if the recording medium is strongly conveyed to the protective film, it is possible to effectively prevent the protective film from peeling off, and a highly reliable thermal printer is realized.
[0054]
Further, when the bond between carbon atoms in the protective film is mainly composed of a covalent bond involving sp ² hybrid orbitals, a large number of free electrons present in the protective film are well captured by hydrogen contained in the protective film. There is an advantage that the insulating property of the protective film can be effectively increased.
[Brief description of the drawings]
FIG. 1 is a sectional view of a thermal head according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a sputtering apparatus used when manufacturing the protective film of FIG.
FIG. 3 is a schematic configuration diagram of a thermal printer configured by incorporating the thermal head of FIG. 1;
FIG. 4 is a sectional view of a thermal head according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate 2, 2a ... Glaze layer 3 ... Heating element 4 ... Electrode 5 ... Protective film 10 ... Platen roller (conveying means)
11a, 11b, 11c, 11d... Transport rollers (transport means)
T: thermal head C: driving means

Claims (7)

A heating element, a pair of electrodes connected to the heating element, and a protective film that covers the heating element and the pair of electrodes, wherein the protective film is mainly composed of an inorganic material containing hydrogen.
A thermal head, wherein the hydrogen content in the lower region of the protective film is set to be smaller than in other regions. The thermal head according to claim 1, wherein the protective film contains carbon and silicon as main components. 3. The thermal head according to claim 1, wherein the carbon-carbon bonds are mainly composed of covalent bonds on sp ² hybrid orbitals. 4. 4. The thermal head according to claim 1, wherein an intermediate layer made of an insulating material is interposed between the protective film and the heating element. A method for manufacturing a thermal head, comprising: a heating element, a pair of electrodes connected to the heating element, and a protection film covering the heating element and the pair of electrodes, and formed of a material containing hydrogen.
A step of using a gas containing hydrogen in forming the protective film, and reducing the amount of hydrogen used in an initial stage of the protective film formation from an initial stage onward. Method. The method according to claim 5, wherein the protective film is formed by reactive sputtering using the gas containing hydrogen as a reactive gas. 5. A thermal printer, comprising: the thermal head according to claim 1; transport means for transporting a recording medium onto the heating element; and drive means for driving the thermal head.

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