JP2012030439A - Thermal head and thermal printer including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal head capable of preventing peeling of a wear-resistant layer and to provide a thermal printer including the thermal head.SOLUTION: The thermal head X includes: a substrate 7; electrode wiring 17c, 19 formed in pairs on the substrate 7; an electrical resistance body 9 connected to both of the electrode wiring 17c, 19 formed in pairs; and a protective layer 25 formed on the electrode wiring 17c, 19 and the electrical resistance body 9. The protective layer 25 includes: an electrical insulating layer 25A formed on the electrode wiring 17c, 19 and the electrical resistance body 9 and mainly composed of Si; the wear-resistant layer 25B formed on the electrical insulating layer 25A and comprising TaO; and a first adhesion layer 25C interposed between the electrical insulating layer 25A and the wear-resistant layer 25B and comprising SiON.

Description

  The present invention relates to a thermal head and a thermal printer including the same.

Conventionally, various thermal heads have been proposed as printing devices such as facsimiles and video printers. For example, a thermal head described in Patent Document 1 includes a substrate, a resistor layer formed on the substrate, an electrode wiring (conductor layer) formed in pairs on the resistor layer, a resistor layer, And a protective layer formed on the electrode wiring. In Patent Document 1, for example, an oxidation resistant layer made of SiN is formed on the resistor layer and the electrode wiring, and an abrasion resistant layer made of Ta ₂ O ₅ is formed on the oxidation resistant layer. In addition, it is described that a protective layer is constituted by a wear-resistant layer.

Japanese Patent Laid-Open No. 58-72477

In the thermal head described in Patent Document 1, a wear-resistant layer made of Ta ₂ O ₅ is formed on an oxidation-resistant layer made of SiN. Therefore, due to the difference in thermal expansion coefficient between the oxidation resistant layer and the wear resistant layer, there is a problem that the wear resistant layer is easily peeled off from the oxidation resistant layer.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a thermal head that can reduce the occurrence of peeling of the wear-resistant layer and a thermal printer including the thermal head.

A thermal head according to an embodiment of the present invention includes a substrate, electrode wirings formed in pairs on the substrate, and electrical resistors connected to both of the electrode wirings formed in pairs. A protective layer formed on the electrode wiring and the electric resistor, and the protective layer is formed on the electrode wiring and the electric resistor, and an electric insulating layer composed mainly of Si; A wear-resistant layer made of Ta ₂ O ₅ formed on the electrical insulating layer, and a first adhesion layer made of SiON interposed between the electrical insulating layer and the wear-resistant layer. And

The thermal head according to an embodiment of the present invention further includes a second adhesion layer that is interposed between the first adhesion layer and the wear-resistant layer and is made of a mixture of SiON and Ta ₂ O _5. May be.

  In the thermal head according to an embodiment of the present invention, the electrical insulating layer may be made of SiN, SiON, or SiAlON.

  A thermal printer according to an embodiment of the present invention includes the thermal head according to an embodiment of the present invention, a transport mechanism that transports a recording medium onto the plurality of heating units, and a recording medium on the plurality of heating units. And a platen roller that presses.

ADVANTAGE OF THE INVENTION According to this invention, the thermal head which can reduce generation | occurrence | production of peeling of an abrasion-resistant layer, and a thermal printer provided with this can be provided.

It is a top view which shows one Embodiment of the thermal head of this invention. It is the II-II sectional view taken on the line of the thermal head of FIG. FIG. 3 is an enlarged view of a region P shown in FIG. 2. It is a figure which shows schematic structure of one Embodiment of the thermal printer of this invention. FIG. 3 is an enlarged view showing a modification of the thermal head of the present invention in a region P shown in FIG. 2. FIG. 3 is an enlarged view showing a modification of the thermal head of the present invention in a region P shown in FIG. 2. FIG. 3 is an enlarged view showing a modification of the thermal head of the present invention in a region P shown in FIG. 2.

  Hereinafter, an embodiment of a thermal head of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the thermal head X of the present embodiment includes a radiator 1, a head substrate 3 disposed on the radiator 1, and a flexible printed wiring board 5 ( Hereinafter referred to as FPC5). In FIG. 1, illustration of the FPC 5 is omitted, and a region where the FPC 5 is arranged is indicated by a two-dot chain line.

  The radiator 1 is formed in a plate shape and has a rectangular shape in plan view. The radiator 1 is made of, for example, a metal material such as copper or aluminum, and radiates a part of the heat generated in the heat generating portion 9 of the head base 3 that does not contribute to printing as will be described later. It has a function. The head base 3 is bonded to the upper surface of the radiator 1 by a double-sided tape, an adhesive, or the like (not shown).

  The head base 3 has a rectangular substrate 7 in plan view, a plurality of (24 in the illustrated example) heating units 9 provided on the substrate 7 and arranged along the longitudinal direction of the substrate 7, and the heating unit 9. And a plurality (three in the illustrated example) of driving ICs 11 arranged side by side on the substrate 7 along the arrangement direction.

  The substrate 7 is made of an electrically insulating material such as alumina ceramic, a semiconductor material such as single crystal silicon, or the like.

  A heat storage layer 13 is formed on the upper surface of the substrate 7. The heat storage layer 13 includes a base portion 13a formed on the entire top surface of the substrate 7, and a raised portion 13b extending in a strip shape along the arrangement direction of the plurality of heat generating portions 9 and having a substantially semi-elliptical cross section. Yes. The raised portions 13b act so as to favorably press the recording medium to be printed against a protective layer 25 described later formed on the heat generating portion 9.

  In addition, the heat storage layer 13 is made of, for example, glass having low thermal conductivity, and temporarily accumulates part of the heat generated in the heat generating part 9 to increase the temperature of the heat generating part 9. The time required is shortened and the thermal response characteristic of the thermal head X is enhanced. The heat storage layer 13 is formed, for example, by applying a predetermined glass paste obtained by mixing a glass powder with an appropriate organic solvent onto the upper surface of the substrate 7 by screen printing or the like, and baking it at a high temperature. Is done.

As shown in FIG. 2, an electrical resistance layer 15 is provided on the upper surface of the heat storage layer 13. The electrical resistance layer 15 is interposed between the heat storage layer 13 and a common electrode wiring 17, an individual electrode wiring 19, and an IC-FPC connection wiring 21 which will be described later. As shown in FIG. A region (hereinafter referred to as an intervening region) having the same shape as the common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21, and a plurality of (in the illustrated example, exposed from between the common electrode wiring 17 and the individual electrode wiring 19). 24 areas) (hereinafter referred to as exposed areas). In FIG. 1, the intervening region of the electric resistance layer 15 is hidden by the common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21.

  Each exposed region of the electrical resistance layer 15 forms the heat generating portion 9 described above. The plurality of exposed regions (heat generating portions 9) are arranged in a row on the raised portion 13b of the heat storage layer 13 as shown in FIG. The plurality of heat generating portions 9 are illustrated in a simplified manner in FIG. 1 for convenience of explanation, but are arranged at a density of 600 dpi to 2400 dpi (dot per inch), for example. In the present embodiment, the heat generating portion 9 corresponds to the electrical resistor in the present invention.

  The electric resistance layer 15 is made of a material having a relatively high electric resistance, such as TaN, TaSiO, TaSiNO, TiSiO, TiSiCO, or NbSiO. Therefore, when a voltage is applied between the common electrode wiring 17 and the individual electrode wiring 19 which will be described later and a current is supplied to the heat generating portion 9, the heat generating portion 9 generates heat due to Joule heat generation.

  As shown in FIGS. 1 and 2, the common electrode wiring 17, the plurality of individual electrode wirings 19, and the plurality of IC-FPC connections are provided on the upper surface of the electric resistance layer 15 (more specifically, the upper surface of the intervening region). A wiring 21 is provided. The common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21 are formed of a conductive material. For example, any one metal of aluminum, gold, silver, and copper, or these It is made of an alloy.

  The common electrode wiring 17 is for connecting the plurality of heat generating portions 9 and the FPC 5. As shown in FIG. 1, the common electrode wiring 17 includes a main wiring portion 17 a extending along one long side (the left long side in the illustrated example) of the substrate 7, and one and the other short sides of the substrate 7. Extending along each of the two sub-wiring portions 17b whose one end (the left-hand end in the illustrated example) is connected to the main wiring portion 17a, and individually extending from the main wiring portion 17a toward each heat generating portion 9, The front end portion (right end portion in the illustrated example) has a plurality of (24 in the illustrated example) lead portions 17 c connected to the heat generating portions 9. And this common electrode wiring 17 electrically connects between FPC5 and each heat-emitting part 9 by connecting the other end part (right side edge part in FIG. 1) of subwiring part 17b to FPC5. ing.

  The plurality of individual electrode wirings 19 are for connecting each heat generating part 9 and the drive IC 11. As shown in FIG. 1 and FIG. 2, each individual electrode wiring 19 has one end (left end in the illustrated example) connected to the heat generating unit 9 and the other end (right end in the illustrated) is driven. In order to be arranged in the arrangement area of the ICs 11, the heating parts 9 individually extend in a band shape toward the arrangement area of the driving ICs 11. Then, the other end portion of each individual electrode wiring 19 is connected to the drive IC 11, whereby the heat generating portions 9 and the drive IC 11 are electrically connected. More specifically, the individual electrode wiring 19 divides a plurality of heat generating portions 9 into a plurality of groups (three in the illustrated example), and the heat generating portions 9 of each group are connected to a drive IC 11 provided corresponding to each group. Electrically connected.

  In the present embodiment, the lead portion 17c of the common electrode wiring 17 and the individual electrode wiring 19 are connected to the heat generating portion 9 as described above, and the lead portion 17c and the individual electrode wiring 19 are arranged to face each other. Has been. In the present embodiment, the electrode wirings connected to the heat generating portion 9 (electrical resistor) are thus formed in pairs. That is, in the present embodiment, the lead portion 17c and the individual electrode wiring 19 constitute an electrode wiring formed as a pair in the present invention.

  The plurality of IC-FPC connection wirings 21 are for connecting the driving IC 11 and the FPC 5. As shown in FIGS. 1 and 2, each IC-FPC connection wiring 21 has one end portion (left end portion in the illustrated example) disposed in a region where the drive IC 11 is disposed, and the other end portion (right end portion in the illustrated example). Part) extends in a strip shape so as to be arranged in the vicinity of the other long side of the substrate 7 (the long side on the right side in the illustrated example). The plurality of IC-FPC connection wires 21 are electrically connected between the drive IC 11 and the FPC 5 by connecting one end to the drive IC 11 and the other end to the FPC 5. Yes.

  More specifically, the plurality of IC-FPC connection wirings 21 connected to each driving IC 11 are configured by a plurality of wirings having different functions. Specifically, the plurality of IC-FPC connection wirings 21 include, for example, an IC power supply wiring for supplying a power supply current for operating the driving IC 11, a driving IC 11, and an individual electrode wiring connected to the driving IC 11. A ground electrode wiring for holding 19 at a ground potential (for example, 0 V to 1 V) and an electric signal for operating the driving IC 11 so as to control an on / off state of a switching element in the driving IC 11 to be described later are supplied. IC control wiring for this purpose.

  As shown in FIGS. 1 and 2, the drive IC 11 is disposed corresponding to each group of the plurality of heat generating portions 9, and the other end portion (right end portion in the illustrated example) of the individual electrode wiring 19. It is connected to one end portion (left end portion in the illustrated example) of the IC-FPC connection wiring 21. This drive IC 11 is for controlling the energization state of each heat generating part 9, and has a plurality of switching elements inside, and is energized when each switching element is in an on state. A well-known thing which becomes a non-energized state in an OFF state can be used.

  Each drive IC 11 is provided with a plurality of switching elements (not shown) therein so as to correspond to each individual electrode wiring 19 connected to each drive IC 11. As shown in FIG. 2, each drive IC 11 has one connection terminal 11a (hereinafter referred to as the first connection terminal 11a) connected to each switching element (not shown) as an individual electrode wiring. 19 and the other connection terminal 11b (hereinafter, the second connection terminal 11b) connected to each switching element is connected to the ground electrode wiring of the IC-FPC connection wiring 21. It is connected. Thereby, when each switching element of the drive IC 11 is in the ON state, the individual electrode wiring 19 connected to each switching element and the ground electrode wiring of the IC-FPC connection wiring 21 are electrically connected.

  The electric resistance layer 15, the common electrode wiring 17, the individual electrode wiring 19 and the IC-FPC connection wiring 21 are formed by, for example, a conventionally well-known thin film forming method such as a sputtering method on the heat storage layer 13. After sequentially laminating by a technique, this laminate is formed by processing it into a predetermined pattern using a conventionally known photoetching or the like. The common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21 can be simultaneously formed by the same process.

  As shown in FIGS. 1 and 2, on the heat storage layer 13 formed on the upper surface of the substrate 7, a protective layer 25 covering the heat generating portion 9, a part of the common electrode wiring 17 and a part of the individual electrode wiring 19. Is formed. In FIG. 1, for convenience of explanation, the formation region of the protective layer 25 is indicated by a one-dot chain line, and illustration of these is omitted. In the illustrated example, the protective layer 25 is provided so as to cover the left region of the upper surface of the heat storage layer 13. As a result, the first protective film 25 is formed on the heat generating portion 9, the main wiring portion 17 a of the common electrode wiring 17, a part of the sub wiring portion 17 b (left region), the lead portion 17 c and the individual electrode wiring 19. Yes. In the present embodiment, the protective layer 25 corresponds to the protective layer in the present invention.

The protective layer 25 protects the area covered with the heat generating portion 9, the common electrode wiring 17 and the individual electrode wiring 19 from corrosion due to adhesion of moisture or the like contained in the atmosphere and wear due to contact with the recording medium to be printed. Is to do.

  More specifically, as shown in FIG. 3, the protective layer 25 is formed on the electrical insulating layer 25 </ b> A formed on the heat generating portion 9, the common electrode wiring 17 and the individual electrode wiring 19, and on the electrical insulating layer 25 </ b> A. A first adhesion layer 25B and an abrasion-resistant layer 25C formed on the first adhesion layer 25B are provided.

  The electrical insulating layer 25A is composed mainly of Si and has electrical insulation. As shown in FIG. 3, the electrical insulating layer is in contact with both the common electrode wiring 17 and the individual electrode wiring 19, but by having such an electrical insulation property, the common electrode wiring 17 and the individual electrode wiring A short circuit with the wiring 19 is prevented. The electrical insulating layer 25A can be formed of, for example, SiN, SiON, SiAlON, or the like. The thickness of the electrical insulating layer 25A is, for example, 2 μm to 12 μm.

The wear-resistant layer 25C located at the uppermost layer of the protective layer 25 is made of Ta ₂ O ₅ . The thickness of the wear resistant layer 25C is, for example, 1 μm to 5 μm.

  The first adhesion layer 25B is interposed between the electrical insulating layer 25A and the wear resistant layer 25C, and is formed of SiON. The thickness of the first adhesion layer 25B is, for example, 0.1 μm to 0.5 μm.

  The protective layer 25 having the electrical insulating layer 25A, the first adhesion layer 25B, and the wear-resistant layer 25C can be formed as follows, for example.

First, the electrical insulating layer 25 </ b> A is formed on the heat generating portion 9, the common electrode wiring 17 and the individual electrode wiring 19. Specifically, sputtering is performed using a sintered body or the like containing Si as a main component as a sputtering target to form an electrical insulating layer 25A configured with Si as a main component. At this time, when the electrical insulating layer 25A is formed of SiN, for example, a sintered body of SiN can be used as a sputtering target. When the electrical insulating layer 25A is formed of SiON, for example, a sintered body in which SiN and SiO ₂ are mixed at a mixing ratio of 50:50 can be used as a sputtering target. In the case of forming an electrically insulating layer 25A in sialon can sintered body of the general formula _{Si 6-Z AL Z O Z} N 8-Z , for example, Z = 1 for Si ₅ ALON ₇ to be a sputtering target .

Next, a first adhesion layer 25B is formed on the electrical insulating layer 25A. Specifically, for example, sputtering is performed using a sintered body in which SiN and SiO ₂ are mixed at a mixing ratio of 50:50 as a sputtering target to form the first adhesion layer 25B made of SiON.

Next, the wear resistant layer 25C is formed on the first adhesion layer 25B. Specifically, for example, a sintered body of _Ta 2 _{O 5} performs sputtering as the sputtering target, to form a wear-resistant layer 25C made of _Ta 2 _{O 5.}

  As described above, the protective layer 25 having the electrical insulating layer 25A, the first adhesion layer 25B, and the wear-resistant layer 25C can be formed. In addition, the sputtering performed when forming each layer can use well-known high frequency sputtering and bias sputtering suitably, for example.

As shown in FIGS. 1 and 2, a coating that partially covers the common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21 on the heat storage layer 13 formed on the upper surface of the substrate 7. A layer 27 is provided. In FIG. 1, for convenience of explanation, the formation region of the coating layer 27 is indicated by a one-dot chain line, and illustration thereof is omitted. In the illustrated example, the coating layer 27 is provided so as to partially cover a region on the right side of the protective layer 25 on the upper surface of the heat storage layer 13. The coating layer 27 protects the region covered with the common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21 from oxidation due to contact with the atmosphere and corrosion due to adhesion of moisture contained in the atmosphere. Is to do. The covering layer 27 is formed so as to overlap the end portion of the protective layer 25 as shown in FIG. 2 in order to ensure the protection of the common electrode wiring 17 and the individual electrode wiring 19. The covering layer 27 can be formed of a resin material such as an epoxy resin or a polyimide resin, for example. The covering layer 27 can be formed using a thick film forming technique such as a screen printing method.

  As shown in FIGS. 1 and 2, the sub-wiring portion 17b of the common electrode wiring 17 for connecting the FPC 5 described later and the end of the IC-FPC connecting wiring 21 are exposed from the covering layer 27, which will be described later. Thus, the FPC 5 is connected.

  Further, an opening 27a (see FIG. 2) for exposing the end portions of the individual electrode wiring 19 and the IC-FPC connection wiring 21 for connecting the driving IC 11 is formed in the coating layer 27, and this opening 27a. These wirings are connected to the driving IC 11 via the. In addition, the drive IC 11 is connected to the individual electrode wiring 19 and the IC-FPC connection wiring 21 to protect the drive IC 11 itself and to protect the connection portion between the drive IC 11 and these wirings. It is sealed by being covered with a covering member 29 made of resin such as resin.

  As shown in FIGS. 1 and 2, the FPC 5 extends along the longitudinal direction of the substrate 7 and is connected to the sub-wiring portion 17b of the common electrode wiring 17 and each IC-FPC connection wiring 21 as described above. Yes. This FPC 5 is a well-known one in which a plurality of printed wirings are wired inside an insulating resin layer, and each printed wiring is electrically connected to an external power supply device and control device (not shown) via a connector 31. It has come to be. Such a printed wiring is generally formed of, for example, a metal foil such as a copper foil, a conductive thin film formed by a thin film forming technique, or a conductive thick film formed by a thick film printing technique. Moreover, the printed wiring formed by a metal foil, a conductive thin film, or the like is patterned by, for example, partially etching these by photoetching or the like.

  More specifically, as shown in FIG. 1 and FIG. 2, the FPC 5 has a conductive bonding material in which each printed wiring 5b formed inside the insulating resin layer 5a is exposed at the end on the head base 3 side. For example, the sub-wiring portion of the common electrode wiring 17 is made of a bonding material 32 (see FIG. 2) made of, for example, a solder material or an anisotropic conductive material (ACF) in which conductive particles are mixed in an electrically insulating resin. It is connected to the end of 17b and the end of each IC-FPC connection wiring 21.

  When each printed wiring 5b of the FPC 5 is electrically connected to an external power supply device and control device (not shown) via the connector 31, the common electrode wiring 17 is held at a positive potential (for example, 20V to 24V). The individual electrode wiring 19 is electrically connected to the positive terminal of the power supply apparatus, and the individual electrode wiring 19 is held at a ground potential (for example, 0 V to 1 V) via the ground electrode wiring of the driving IC 11 and the IC-FPC connection wiring 21. It is electrically connected to the negative terminal of the device. For this reason, when the switching element of the drive IC 11 is in the on state, a current is supplied to the heat generating portion 9 and the heat generating portion 9 generates heat.

Similarly, when each printed wiring 5b of the FPC 5 is electrically connected to an external power supply device and control device (not shown) via the connector 31, the IC power wiring of the IC-FPC connection wiring 21 is Similar to the common electrode wiring 17, it is electrically connected to the positive side terminal of the power supply device held at a positive potential. Thereby, the IC to which the driving IC 11 is connected
The power supply current for operating the drive IC 11 is supplied to the drive IC 11 by the potential difference between the IC power supply wiring of the FPC connection wiring 21 and the ground electrode wiring. Further, the IC control wiring of the IC-FPC connection wiring 21 is electrically connected to an external control device that controls the driving IC 11. As a result, the electrical signal transmitted from the control device is supplied to the drive IC 11. By operating the drive IC 11 so as to control the on / off state of each switching element in the drive IC 11 by this electric signal, each heat generating portion 9 can be selectively heated.

  A reinforcing plate 33 made of a resin such as a phenol resin, a polyimide resin, or a glass epoxy resin is provided between the FPC 5 and the radiator 1. The reinforcing plate 33 acts to reinforce the FPC 5 by being adhered to the lower surface of the FPC 5 with a double-sided tape, an adhesive, or the like (not shown). Further, the reinforcing plate 33 is bonded to the upper surface of the radiator 1 by a double-sided tape, an adhesive or the like (not shown), so that the FPC 5 is fixed on the radiator 1.

  Next, an embodiment of the thermal printer of the present invention will be described with reference to FIG. FIG. 4 is a schematic configuration diagram of the thermal printer Z of the present embodiment.

  As shown in FIG. 4, the thermal printer Z of the present embodiment includes the thermal head X, the transport mechanism 40, the platen roller 50, the power supply device 60, and the control device 70 described above. The thermal head X is attached to an attachment surface 80a of an attachment member 80 provided in a housing (not shown) of the thermal printer Z. The thermal head X is arranged such that the arrangement direction of the heat generating portions 9 is along a direction (main scanning direction) (direction perpendicular to the paper surface of FIG. 4) perpendicular to the conveyance direction S of the recording medium P described later. It is attached to the attachment member 80.

  The transport mechanism 40 transports a recording medium P such as thermal paper or image receiving paper onto which ink is transferred in the direction of arrow S in FIG. 25) and has conveying rollers 43, 45, 47, and 49. The transport rollers 43, 45, 47, and 49 are formed by, for example, covering cylindrical shaft bodies 43a, 45a, 47a, and 49a made of metal such as stainless steel with elastic members 43b, 45b, 47b, and 49b made of butadiene rubber or the like. Can be configured. Although not shown, when the recording medium P is an image receiving paper to which ink is transferred, an ink film is transported together with the recording medium P between the recording medium P and the heat generating portion 9 of the thermal head X. Yes.

  The platen roller 50 is for pressing the recording medium P onto the heat generating portion 9 of the thermal head X, and is arranged so as to extend along a direction orthogonal to the conveyance direction S of the recording medium P. Both ends are supported so as to be rotatable while being pressed on the heat generating portion 9. The platen roller 50 can be configured by, for example, covering a cylindrical shaft body 50a made of metal such as stainless steel with an elastic member 50b made of butadiene rubber or the like.

  The power supply device 60 is for supplying a current for causing the heat generating part 9 of the thermal head X to generate heat and a current for operating the drive IC 11 as described above. The control device 70 is for supplying the drive IC 11 with a control signal for controlling the operation of the drive IC 11 in order to selectively heat the heat generating portion 9 of the thermal head X as described above.

  As shown in FIG. 4, the thermal printer Z of the present embodiment conveys the recording medium P onto the heat generating portion 9 by the conveying mechanism 40 while pressing the recording medium onto the heat generating portion 9 of the thermal head X by the platen roller 50. However, it is possible to perform predetermined printing on the recording medium P by selectively causing the heat generating unit 9 to generate heat by the power supply device 60 and the control device 70. When the recording medium P is an image receiving paper or the like, printing on the recording medium P can be performed by thermally transferring ink of an ink film (not shown) conveyed together with the recording medium P to the recording medium P.

According to the thermal head X of the present embodiment, the wear resistant layer 25C that comes into contact with the recording medium during printing is formed of Ta ₂ O ₅ . Since Ta ₂ O ₅ is Vickers hardness and has a hardness of about Hv = 800 to 1000, by forming the wear resistant layer 25C with this Ta ₂ O ₅ , the wear resistance can be enhanced.

Further, in the present embodiment, the recording medium such as paper is improved in wear resistance when printing with the thermal head X due to the following characteristics of Ta ₂ O ₅ forming the wear resistant layer 25C. Occurrence of a phenomenon (so-called sticking) that is conveyed while being caught by 25C can be reduced.

That is, for example, in the thermal head X of the present embodiment, as one of the factors that cause sticking, a foreign matter such as paper dust burns on the wear-resistant layer 25C, so that there is a large gap between the burnt foreign matter and the recording medium. It is mentioned that resistance force arises. On the other hand, when the wear-resistant layer 25C is formed of a material layer mainly composed of Ta, the surface of the wear-resistant layer 25C is scorched along with the moderate wear of the surface of the wear-resistant layer 25C. The foreign matter is detached from the wear resistant layer 25C. Therefore, it is possible to reduce the occurrence of sticking due to the burnt foreign matter. In addition to this, in this embodiment, the wear-resistant layer 25C is formed of Ta ₂ O ₅ which is an oxide of Ta, not pure Ta. Thereby, compared with the case where the wear-resistant layer 25C is formed of pure Ta, the wear-resistant layer 25C is a chemically stable layer, so that the wear-resistant characteristics can be improved. Therefore, in the present embodiment, it is possible to reduce the occurrence of sticking while improving the wear resistance characteristics during printing with the thermal head X.

  Furthermore, according to the thermal head X of the present embodiment, the first adhesion layer 25B made of SiON is interposed between the electrical insulating layer 25A and the wear resistant layer 25C. Therefore, the adhesion of the wear resistant layer 25C on the electrical insulating layer 25A can be improved as compared with the case where the first adhesive layer 25B is not interposed between the electrical insulating layer 25A and the wear resistant layer 25C. The occurrence of peeling of the wear resistant layer 25C can be reduced.

That is, when the first adhesion layer 25B is not interposed between the electrical insulating layer 25A and the wear resistant layer 25C, the electrical insulating layer 25A composed mainly of Si and the wear resistant layer 25C made of Ta ₂ O ₅ In between, Si (silicon) atoms constituting the electrical insulating layer 25A and O (oxygen) atoms constituting the wear resistant layer 25C are mainly bonded. At this time, the bond energy between the Si atom and the O atom is about 108 kcal / mol.

On the other hand, when the first adhesion layer 25B is interposed between the electrical insulation layer 25A and the wear-resistant layer 25C, the electrical insulation layer 25A composed mainly of Si and the first adhesion layer 25B made of SiON In between, Si atoms constituting the electric insulating layer 25A and Si atoms constituting the first adhesion layer 25B are mainly bonded. The bond energy between Si atoms at this time is about 117 kcal / mol. On the other hand, between the first adhesion layer 25B made of SiON and the wear-resistant layer 25C made of Ta ₂ O _5, O atoms constituting the first adhesion layer 25B and O atoms constituting the wear-resistant layer 25C are mainly used. Join. The bond energy between O atoms at this time is about 119 kcal / mol.

  Therefore, when the first adhesion layer 25B is interposed between the electrical insulating layer 25A and the wear-resistant layer 25C as in the present embodiment, the binding energy between the layers is improved compared to the case where the first adhesion layer 25B is not interposed. Therefore, the adhesion of the wear resistant layer 25C onto the electrical insulating layer 25A can be improved. As a result, occurrence of peeling of the wear resistant layer 25C can be reduced.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning.

In the thermal head X of the above-described embodiment shown in FIGS. 1 to 3, the wear-resistant layer 25C is formed on the first adhesion layer 25B, but the present invention is not limited to this. For example, FIG. As shown in FIG. 2, a second adhesion layer 25D made of a mixture of SiON and Ta ₂ O ₅ may be interposed between the first adhesion layer 25B and the wear-resistant layer 25C. As a result, the heat generated between the first adhesion layer 25B and the abrasion-resistant layer 25C as compared with the case where the abrasion-resistant layer 25C is directly formed on the first adhesion layer 25B as shown in FIG. Stress is relieved.

That is, between the first contact layer 25B and the _Ta 2 _O consisting of ₅ wear-resistant layer 25C made of SiON, by interposing the second contact layer 25D made of a mixture of SiON and _Ta 2 _{O 5,} first The difference in thermal expansion coefficient between the adhesion layer 25B and the second adhesion layer 25D is smaller than the difference in thermal expansion coefficient between the first adhesion layer 25B and the wear-resistant layer 25C. Further, the difference in thermal expansion coefficient between the second adhesion layer 25D and the wear-resistant layer 25C is also smaller than the difference in thermal expansion coefficient between the first adhesion layer 25B and the abrasion-resistant layer 25C. Therefore, when the second adhesion layer 25D is interposed between the first adhesion layer 25B and the wear-resistant layer 25C, the thermal stress generated between the layers is relieved compared to the case where the second adhesion layer 25D is not interposed. .

As a result, as shown in FIG. 5, the first adhesion layer is formed by interposing a second adhesion layer 25D made of a mixture of SiON and Ta ₂ O ₅ between the first adhesion layer 25B and the wear-resistant layer 25C. The occurrence of peeling of the wear resistant layer 25C due to the difference in thermal expansion coefficient between 25B and the wear resistant layer 25C can be reduced.

In addition, when the second adhesion layer 25D is interposed between the first adhesion layer 25B and the wear-resistant layer 25C as described above, the SiONs constituting the first adhesion layer 25B and the second adhesion layer 25D are in contact with each other. Since Ta ₂ O ₅ bonded between the layers and constituting the wear-resistant layer 25C and the second adhesion layer 25D are bonded between these layers, adhesion between the layers is ensured.

  Further, when the second adhesion layer 25D is interposed between the first adhesion layer 25B and the wear-resistant layer 25C in this way, the protective layer 25 can be formed, for example, as follows.

  First, an electrical insulating layer 25 </ b> A composed mainly of Si is formed on the heat generating portion 9, the common electrode wiring 17, and the individual electrode wiring 19. The method of forming the electrical insulating layer 25A is the same as that described for the thermal head X of the above embodiment shown in FIGS.

Next, a first adhesion layer 25B is formed on the electrical insulating layer 25A. Specifically, for example, sputtering is performed using a sintered body in which SiN and SiO ₂ are mixed at a mixing ratio of 50:50 as a sputtering target to form the first adhesion layer 25B made of SiON.

Subsequently, a second adhesion layer 25D is formed on the first adhesion layer 25B. Specifically, for example, sputtering is performed using a Ta ₂ O ₅ sintered body as a sputtering target while continuing the sputtering of SiON forming the first adhesion layer 25B. Thereby, the second adhesion layer 25D made of a mixture of SiON and Ta ₂ O ₅ is formed.

Subsequently, an abrasion resistant layer 25C is formed on the second adhesion layer 25D. Specifically, for example, the sputtering of SiON that has been continuously performed in the formation process of the second adhesion layer 25D is stopped, and only the sputtering using the sintered body of Ta ₂ O ₅ as the sputtering target is continued. The wear resistant layer 25C made of Ta ₂ O ₅ is formed.

  As described above, the protective layer 25 having the electrical insulating layer 25A, the first adhesion layer 25B, the second adhesion layer 25D, and the wear-resistant layer 25C can be formed. In addition, the sputtering performed when forming each layer can use well-known high frequency sputtering and bias sputtering suitably, for example.

  In the thermal head X shown in FIGS. 1 to 3, the raised portion 13 b is formed on the heat storage layer 13, and the electric resistance layer 15 is formed on the raised portion 13 b, but this is not limitative. . For example, the heat generating portion 9 of the electric resistance layer 15 may be disposed on the base portion 13 b of the heat storage layer 13 without forming the raised portion 13 b in the heat storage layer 13. Alternatively, the electric resistance layer 15 may be disposed on the substrate 7 without forming the heat storage layer 13.

  In the thermal head X shown in FIGS. 1 to 3, the common electrode wiring 17 and the individual electrode wiring 19 are formed on the electric resistance layer 15, but both the common electrode wiring 17 and the individual electrode wiring 19 are heated. As long as it is connected to 9 (electric resistor), it is not limited to this. For example, as shown in FIG. 6, the common electrode wiring 17 and the individual electrode wiring 19 are formed on the heat storage layer 13, and the electric resistance layer 15 is formed on the heat storage layer 13 on which the common electrode wiring 17 and the individual electrode wiring 19 are formed. The heat generating portion 9 may be configured by forming Alternatively, as shown in FIG. 7, the common electrode wiring 17 and the individual electrode wiring 19 are formed on the heat storage layer 13, and the electric resistance layer 15 is formed only in a region between the common electrode wiring 17 and the individual electrode wiring 19. By doing so, the heat generating portion 9 may be configured.

X Thermal Head 1 Heat Dissipator 3 Head Base 5 Flexible Printed Circuit Board 7 Substrate 9 Heating Element (Electric Resistor)
11 Drive IC
17 Common electrode wiring 17a Main wiring part 17b Sub wiring part 17c Lead part (electrode wiring)
19 Individual electrode wiring (electrode wiring)
21 IC-FPC connection wiring 25 Protective layer 25A Electrical insulation layer 25B Abrasion resistant layer 25C First adhesion layer 25D Second adhesion layer 27 Coating layer

Claims (4)

A substrate,
Electrode wirings formed in pairs on the substrate;
An electrical resistor connected to both electrode wires formed in pairs;
A protective layer formed on the electrode wiring and the electric resistor,
The protective layer is
An electric insulating layer formed on the electrode wiring and the electric resistor and composed mainly of Si;
A wear-resistant layer formed on the electrical insulating layer and made of Ta ₂ O ₅ ;
A thermal head comprising a first adhesion layer made of SiON and interposed between the electrical insulating layer and the wear-resistant layer. 2. The thermal head according to claim 1, further comprising a second adhesion layer which is interposed between the first adhesion layer and the wear-resistant layer and is made of a mixture of SiON and Ta ₂ O ₅ .   The thermal head according to claim 1, wherein the electrical insulating layer is made of SiN, SiON, or SiAlON. A thermal head according to any one of claims 1 to 3, a transport mechanism for transporting a recording medium onto the plurality of heat generating portions, and a platen roller for pressing the recording medium onto the plurality of heat generating portions. Features a thermal printer.