CN114379242A

CN114379242A - Thermal print head, method of manufacturing the same, and thermal printer

Info

Publication number: CN114379242A
Application number: CN202111126859.3A
Authority: CN
Inventors: 渡边俊夫
Original assignee: Rohm Co Ltd
Current assignee: Rohm Co Ltd
Priority date: 2020-10-02
Filing date: 2021-09-26
Publication date: 2022-04-22
Also published as: JP2022059849A

Abstract

The invention provides a thermal print head capable of suppressing disconnection of a comb portion of a common electrode. In addition, a manufacturing method of the thermal print head and a thermal printer with the thermal print head are also provided. The thermal print head of the present invention includes: an independent electrode on the heat storage layer; a common electrode having a comb-tooth portion spaced apart from the individual electrode and opposed to the individual electrode; the independent electrodes and the heating resistor on the comb teeth part; a connection electrode made of a different material from the common electrode and in contact with the common electrode; a first protective film covering a part of the common electrode and the wiring; and a second protective film covering the connection electrode, an end portion of the common electrode in a sub-scanning direction being covered with the connection electrode, one side surface of the connection electrode in the sub-scanning direction being in contact with the second protective film, the other side surface being in contact with the first protective film.

Description

Thermal print head, method of manufacturing the same, and thermal printer

Technical Field

The present embodiment relates to a thermal head, a method of manufacturing the same, and a thermal printer.

Background

The thermal head is provided with a large number of heat generating portions arranged in the main scanning direction on a head substrate, for example. Each of the heat generating portions is formed by laminating a common electrode and an individual electrode on a resistor layer formed on a print head substrate with a glaze layer interposed therebetween so that a part of the resistor layer is exposed, wherein end portions of the common electrode and the individual electrode face each other. When current is passed between the common electrode and the individual electrode, the exposed portion (heat-generating portion) of the resistor layer generates heat by joule heat. The heat is transferred to a print medium (e.g., thermal paper for producing barcode labels or receipts), and printing can be performed on the print medium.

The common electrode, the individual electrode, and the like are patterned by screen printing paste containing a metal such as gold.

The common electrode and the individual electrode are in contact with a connection electrode and a wiring for supplying a voltage from the outside to the common electrode and the individual electrode, respectively, the connection electrode is formed with an electrode pattern by screen printing using a paste of a metal such as silver, and the wiring is formed by a photolithography process using a metal such as gold or silver. Since gold is expensive, a technique of using silver as a relatively inexpensive metal having good conductivity has been proposed from the viewpoint of reducing the product cost.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2000-141729.

Patent document 2: japanese patent laid-open No. 5-89716.

Disclosure of Invention

Technical problem to be solved by the invention

However, when the material of the common electrode and the material of the connection electrode are different metals, a kirkendall phenomenon occurs in which the interface between the common electrode and the connection electrode moves due to heating. For example, when the common electrode is made of gold and the connection electrode is made of silver, the silver serving as a material of the connection electrode diffuses toward the common electrode due to the action of heat. This diffusion may cause a kirkendall void to be generated in the common electrode, and if the kirkendall void is generated in the comb-tooth portion of the common electrode, the comb-tooth portion may be a thin electrode, which may cause disconnection. Further, the ductility of gold, which is a material of the common electrode, is reduced by the diffusion of silver, and the comb teeth are strained by heating, which may cause wire breakage.

One aspect of the present embodiment provides a thermal print head capable of suppressing disconnection of comb-teeth portions of a common electrode. In addition, another aspect of the present embodiment provides a method for manufacturing the thermal print head. Further, another aspect of the present embodiment provides a thermal printer having the thermal head.

Means for solving the problems

In this embodiment, after the first protective film covering the heating resistor, the individual electrodes, a part of the common electrode, and the wiring in contact with the individual electrodes is formed, the connection electrode in contact with the common electrode is formed, whereby the end portion of the common electrode in the sub-scanning direction is covered with the connection electrode, one side surface of the connection electrode in the sub-scanning direction is in contact with the second protective film, and the other side surface of the connection electrode in the sub-scanning direction is in contact with the first protective film. With this configuration, the path through which the material of the connection electrode diffuses toward the comb teeth of the common electrode can be narrowed, and the diffusion region can be suppressed from reaching the comb teeth. Therefore, disconnection of the comb teeth of the common electrode can be suppressed. One aspect of the present embodiment is as follows.

An aspect of the present embodiment provides a thermal print head including: a heat storage layer; a separate electrode on the heat storage layer; a common electrode having a comb-tooth portion spaced apart from the individual electrode and opposed to the individual electrode; the independent electrodes and the heating resistor on the comb teeth part; a connection electrode made of a different material from the common electrode and in contact with the common electrode; a first protective film covering the heating resistor, the individual electrodes, and a part of the common electrode; and a second protective film covering the connection electrode, an end portion of the common electrode in a sub-scanning direction being covered by the connection electrode, one side surface of the connection electrode in the sub-scanning direction being in contact with the second protective film, the other side surface of the connection electrode in the sub-scanning direction being in contact with the first protective film.

Further, another aspect of the present embodiment provides a thermal printer having the thermal head described above.

Another aspect of the present invention provides a method of manufacturing a thermal head, including forming a heat storage layer, forming an individual electrode and a common electrode having a comb-shaped portion on the heat storage layer, forming a wiring in contact with the individual electrode, forming a heating resistor on the individual electrode and on the common electrode, forming a first protective film covering the heating resistor, the individual electrode, a part of the common electrode, and the wiring, forming a connection electrode in contact with another part of the common electrode after forming the first protective film, and forming a second protective film covering the connection electrode, wherein the individual electrode is spaced apart from the comb-shaped portion of the common electrode and faces the comb-shaped portion, and the common electrode is made of a material different from the connection electrode.

Effects of the invention

In this embodiment, a thermal print head capable of suppressing disconnection of the comb portion of the common electrode can be provided. Further, a method of manufacturing the thermal print head can be provided. Further, a thermal printer having the thermal head can be provided.

Drawings

Fig. 1 is a plan view illustrating a thermal head 100A according to the present embodiment.

Fig. 2 is a sectional view taken along line a-a of fig. 1.

Fig. 3 is a plan view (1) illustrating a method of manufacturing the thermal head 100A according to the present embodiment.

Fig. 4 is a sectional view taken along line a-a of fig. 3.

Fig. 5 is a plan view (2) illustrating a method of manufacturing the thermal head 100A according to the present embodiment.

Fig. 6 is a sectional view taken along line a-a of fig. 5.

Fig. 7 is a plan view (3) illustrating a method of manufacturing the thermal head 100A according to the present embodiment.

Fig. 8 is a sectional view taken along line a-a of fig. 7.

Fig. 9 is a plan view (4) illustrating a method of manufacturing the thermal head 100A according to the present embodiment.

Fig. 10 is a sectional view taken along line a-a of fig. 9.

Fig. 11 is a plan view (5) illustrating a method of manufacturing the thermal head 100A according to the present embodiment.

Fig. 12 is a sectional view taken along line a-a of fig. 11.

Fig. 13 is a plan view (fig. 6) illustrating a method of manufacturing the thermal head 100A according to the present embodiment.

Fig. 14 is a sectional view taken along line a-a of fig. 13.

Fig. 15 is a plan view (7) illustrating a method of manufacturing the thermal head 100A according to the present embodiment.

Fig. 16 is a sectional view taken along line a-a of fig. 15.

Fig. 17 is a sectional view illustrating a thermal head 100B according to the present embodiment.

Fig. 18 is a sectional view illustrating a thermal head 100C of the embodiment.

Fig. 19 is a sectional view illustrating a thermal head 100D of the embodiment.

Fig. 20 is a sectional view illustrating the thermal head according to the present embodiment.

Description of the reference numerals

5 connecting substrate

7 drive IC

8 Heat-dissipating component

15 base plate

31 independent electrode

32 common electrode

32A comb tooth part

32B common part

33 heat storage layer

41 wiring

42. 42a connecting electrode

50 heating resistor

51 heating resistor part

52. 54 protective film

59 connector

81 lead wire

82 resin part

91 paper pressing roller

92 printing medium

100A, 100B, 100C, 100D thermal print head

Detailed Description

Next, the present embodiment will be described with reference to the drawings. In the description of the drawings described below, the same or similar parts are denoted by the same or similar reference numerals. It should be noted that the drawings are schematic, and the relationship between the thickness and the planar size of each constituent member and the like are different from those of the actual products. Therefore, specific thickness and size should be determined by referring to the following description. It is needless to say that the drawings include portions having different dimensional relationships and ratios from each other.

The embodiments described below are illustrative of apparatuses and methods for embodying the technical ideas, but are not limited to the materials, shapes, structures, arrangements, and the like of the respective constituent members. The present embodiment can be variously modified within the scope of the technical idea of the invention.

One specific aspect of the present embodiment is as follows.

< 1 > a thermal print head comprising: a heat storage layer; a separate electrode on the heat storage layer; a common electrode having a comb-tooth portion spaced apart from the individual electrode and opposed to the individual electrode; the independent electrodes and the heating resistor on the comb teeth part; a connection electrode made of a different material from the common electrode and in contact with the common electrode; a first protective film covering the heating resistor, the individual electrodes, and a part of the common electrode; and a second protective film covering the connection electrode, an end portion of the common electrode in a sub-scanning direction being covered by the connection electrode, one side surface of the connection electrode in the sub-scanning direction being in contact with the second protective film, the other side surface of the connection electrode in the sub-scanning direction being in contact with the first protective film.

< 2 > the thermal head as < 1 > wherein the common electrode comprises gold and the connection electrode comprises silver.

The thermal head described in < 3 > such as < 1 > or < 2 > further includes a wiring in contact with the individual electrode, and the connection electrode is thicker than the wiring.

The thermal head of any one of < 4 > such as < 1 > < 3 >, wherein the connection electrode has a protrusion that contacts at least a portion of an upper surface of the first protection film.

The thermal print head of any one of < 5 > such as < 1 > - < 4 >, wherein the second protective film covers the first protective film.

The thermal head of any one of < 6 > to < 5 >, wherein the second protective film is in contact with an upper surface of the first protective film and an upper surface of the connection electrode.

The thermal head of any one of < 7 > such as < 1 > - < 6 >, wherein the individual electrodes are spaced apart from the comb-teeth portion in the main scanning direction.

< 8 > a thermal printer having the thermal head described in any one of < 1 > -to < 7 >.

< 9 > a method for manufacturing a thermal head, wherein a heat storage layer is formed, an individual electrode and a common electrode having a comb-tooth portion are formed on the heat storage layer, a wiring in contact with the individual electrode is formed, a heating resistor is formed on the individual electrode and the common electrode, a first protective film covering the heating resistor, the individual electrode, a part of the common electrode, and the wiring is formed, a connection electrode in contact with the other part of the common electrode is formed after the first protective film is formed, a second protective film covering the connection electrode is formed, the individual electrode is opposed to the comb-tooth portion of the common electrode with a gap therebetween, and the common electrode is made of a material different from the connection electrode.

< 10 > the method of manufacturing a thermal head as < 9 > wherein an end portion of the common electrode in a sub-scanning direction is covered with the connection electrode, one side surface of the connection electrode in the sub-scanning direction is in contact with the second protective film, and the other side surface of the connection electrode in the sub-scanning direction is in contact with the first protective film.

The method for manufacturing a thermal print head of < 11 > such as < 9 > or < 10 > wherein the common electrode comprises gold and the connection electrode comprises silver.

The method of manufacturing a thermal head according to any one of < 12 > to < 9 > to < 11 >, wherein the connection electrode is thicker than the wiring.

The method of manufacturing a thermal head of any one of < 13 > to < 9 > < 12 >, wherein the connection electrode has a protrusion that contacts at least a portion of an upper surface of the first protection film.

The method of manufacturing a thermal print head of any one of < 14 > to < 13 >, wherein the second protective film covers the first protective film.

The method of manufacturing a thermal head according to any one of < 15 > to < 9 > < 14 >, wherein the second protective film is in contact with an upper surface of the first protective film and an upper surface of the connection electrode.

The method of manufacturing a thermal head according to any one of < 16 > to < 9 > to < 15 >, wherein the connection electrode is formed by screen printing a metal paste, and the wiring is formed by a photolithography process.

Thermal print head

The thermal print head according to the present embodiment will be described with reference to the drawings.

Fig. 1 is a plan view showing a thermal head. Fig. 2 is a sectional view taken along line a-a of fig. 1. Fig. 1 and 2 show a part of a thermal head (corresponding to 1 thermal head), and in the present embodiment, this 1 thermal head is referred to as a single-sheet thermal head 100A. The thermal print head 100A includes: a substrate 15; a heat storage layer 33 on the substrate 15; a plurality of individual electrodes 31 and a common electrode 32 having comb-teeth 32A on the heat storage layer 33; a heating resistor 50 on the individual electrode 31 and on the comb-teeth 32A of the common electrode 32; a wiring 41 in contact with the individual electrode 31; a connection electrode 42 in contact with the common electrode 32; a protective film 52 covering the heat storage layer 33, the individual electrodes 31, a part of the common electrode 32, the heating resistor 50, and the wiring 41; and a protective film 54 covering the connection electrode 42. The individual electrode 31 is spaced apart from the comb-teeth 32A of the common electrode 32 in the main scanning direction X and faces the comb-teeth 32A. The common electrode 32 is made of a material different from that of the connection electrode 42, an end portion of the common electrode 32 in a sub-scanning direction to be described later is covered with the connection electrode 42, one side surface of the connection electrode 42 in the sub-scanning direction is in contact with the protective film 54, and the other side surface of the connection electrode 42 is in contact with the protective film 52.

The heating resistor 50 includes a plurality of heating resistor portions 51 that generate heat by currents flowing through the individual electrodes 31 and the common electrode 32. In the plurality of heat-generating resistive portions 51, each heat-generating resistive portion 51 is independently formed between the individual electrode 31 and the common electrode 32. Fig. 1 omits a plurality of heat generation resistor portions 51. The plurality of heat generation resistor units 51 are linearly arranged on the heat storage layer 33. In addition, the protective film 54 is omitted from fig. 1 for ease of understanding.

In the present embodiment, a direction in which the plurality of heat generation resistor portions 51 linearly extend is defined as a main scanning direction X, a direction perpendicular to the main scanning direction X and parallel to the upper surface of the substrate 15 is defined as a sub-scanning direction Y, and a direction corresponding to the thickness of the substrate 15 is defined as a thickness direction Z. In other words, the thickness direction Z is a direction perpendicular to the main scanning direction X and the sub-scanning direction Y, respectively.

The substrate 15 is made of ceramic or a single crystal semiconductor. As the ceramic, for example, alumina or the like can be used. Silicon or the like can be used as the single crystal semiconductor. From the viewpoint of heat dissipation, it is preferable to use alumina having high thermal conductivity for the substrate 15.

A heat storage layer 33 (also referred to as a glaze layer) having a function of storing heat is stacked on the substrate 15 made of alumina or the like. The heat storage layer 33 stores heat generated from the heat generation resistor 51 described later. The heat storage layer 33 may be made of an insulating material, for example, silicon oxide or silicon nitride, which is a main component of glass. The dimension of the heat storage layer 33 in the thickness direction Z is not particularly limited, and is, for example, 30 to 80 μm, preferably 40 to 60 μm.

The individual electrodes 31 and the common electrode 32 formed of the metal paste are provided on the heat storage layer 33. The individual electrodes 31 and the common electrode 32 are obtained by forming an electrode pattern by applying a metal paste using a screen printing method or the like.

As the metal paste, for example, a paste containing metal particles of copper, silver, palladium, iridium, platinum, gold, or the like can be used. From the viewpoint of the characteristics and ionization tendency of the metal, copper, silver, platinum and gold are preferable, and gold is more preferable. The solvent contained in the metal paste has a function of uniformly dispersing the metal particles, and examples thereof include 1 kind of solvent selected from ester solvents, ketone solvents, glycol ether solvents, aliphatic solvents, alicyclic solvents, aromatic solvents, alcohol solvents, water, and 2 or more kinds of solvents mixed together, but are not limited thereto.

Examples of the ester-based solvent include ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, pentyl acetate, ethyl lactate, and dimethyl carbonate. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone benzene, diisobutyl ketone, diacetone alcohol, isophorone, and cyclohexanone. Examples of the glycol ether solvent include ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, and the like, and acetates of these monoethers, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and the like.

Examples of the aliphatic solvent include n-heptane, n-hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane. Examples of the alicyclic solvent include methylcyclohexane, ethylcyclohexane, and cyclohexane. Examples of the aromatic solvent include toluene, xylene, and tetralin. Examples of the alcohol solvent (excluding the glycol ether solvent) include ethanol, propanol, and butanol.

The metal paste may contain a dispersant, a surface treatment agent, a friction modifier, an infrared absorber, an ultraviolet absorber, an aromatic agent, an antioxidant, an organic pigment, an inorganic pigment, an antifoaming agent, a silane coupling agent, a titanate coupling agent, a plasticizer, a flame retardant, a humectant, an ion scavenger, and the like, as required.

The individual electrodes 31 are strip-shaped and extend substantially in the sub-scanning direction Y, and they are not electrically connected to each other. Therefore, when a printer incorporating a thermal head is used, the individual electrodes 31 can be applied with different potentials. An independent pad portion is connected to an end portion of each independent electrode 31. The individual pad portion is provided apart from the heating resistor 50 and in contact with the wiring 41.

The common electrode 32 is a portion having an opposite electrical polarity to the plurality of individual electrodes 31 when the printer incorporating the thermal head is used. The common electrode 32 includes comb-teeth 32A and a common portion 32B that connects the comb-teeth 32A together. The common portion 32B is formed in the main scanning direction X along the edge of the upper side of the substrate 15. Here, in the sub-scanning direction Y, the direction in which the common electrode 32 is located when viewed from the individual electrode 31 is set to the upper side in the sub-scanning direction Y. Each comb tooth portion 32A is a belt shape extending in the sub-scanning direction Y. The tip of each comb-tooth portion 32A is located in a region between the tips of the adjacent 2 individual electrodes 31, and faces the 2 individual electrodes 31 at a predetermined interval in the main scanning direction X.

The tip end of each comb-tooth portion 32A may face the tip end of each individual electrode 31 at a predetermined interval in the sub-scanning direction Y. In this case, the heat-generating resistor 51 is preferably formed only in a region where the tip of the comb-teeth 32A faces the tip of the individual electrode 31. In other words, it is preferable that the heat generation resistor portion 51 is not disposed in a region other than a region where the tip end portion of the comb-teeth portion 32A faces the tip end portion of the individual electrode 31 in the main scanning direction X.

In the heating resistor 50, a portion through which the current flows from the individual electrode 31 and the common electrode 32 generates heat. Specifically, the heating resistors 50 can selectively generate heat by independently applying a heating voltage according to a print signal transmitted from the outside to the driver IC or the like. The heat generation resistor portion 51 is independently energized in accordance with a print signal to selectively generate heat. By this heat generation, a print dot is formed. The heating resistor 50 is made of a material having a higher resistivity than the materials constituting the individual electrodes 31 and the common electrode 32, and may be made of, for example, ruthenium oxide. The heating resistor 50 can be formed by supplying a resistor paste using screen printing or a dispenser and sintering the same. In the present embodiment, the dimension of the heating resistor 50 in the thickness direction Z is, for example, about 1 to 10 μm.

The wiring 41 is in contact with the individual electrode 31. The wiring 41 has a function of supplying a voltage to the individual electrode 31 from the outside, and is formed by a photolithography process using a metal such as gold or silver, for example.

The connection electrode 42 is in contact with the common electrode 32. The connection electrode 42 has a function of supplying a voltage to the common electrode 32 from the outside, and is obtained by forming an electrode pattern by applying a metal paste such as silver by using a screen printing method or the like, for example. The electrode pattern is formed by sintering the applied metal paste, but the metal paste before sintering has higher fluidity than the metal paste after sintering, and this high fluidity may cause the electrode pattern to be formed at a position deviated from a set position, for example, the surface area of the connection electrode 42 in contact with the surface (the surface of the common electrode 32) on which the connection electrode 42 is formed may be enlarged. However, in the present embodiment, since the connection electrode 42 is formed after the protective film 52 described later is formed, the flow of the metal paste can be suppressed by the protective film 52 even before the metal paste is sintered. The protective film 52 can suppress the surface area of the connection electrode 42 in contact with the surface of the common electrode 32 from being enlarged, and can narrow the path through which the material of the connection electrode 42 spreads toward the comb-teeth portion 32A of the common electrode 32.

The connection electrode 42 formed by the screen printing method is thicker than the wiring 41 formed by the photolithography step. Since the amount of diffusion of the material varies depending on the thickness, when the material of the connection electrode 42 is the same as the material of the wiring 41, the material of the common electrode 32 is the same as the material of the individual electrode 31, and the material of the connection electrode 42 is different from the material of the wiring 41, the amount of diffusion of the material of the connection electrode 42 into the common electrode 32 is larger than the amount of diffusion of the material of the wiring 41 into the individual electrode 31. Therefore, by providing the protective film 52 described later so as to be in contact with one side surface of the connection electrode 42 in the sub-scanning direction and providing the protective film 54 so as to be in contact with the other side surface of the connection electrode 42 in the sub-scanning direction, it is possible to suppress the connection electrode 42 from being in contact with the comb-teeth portion 32A near the comb-teeth portion 32A of the common electrode 32 in contact with the bottom surface of the protective film 52.

The protective film 52 covers the individual electrodes 31, a part of the common electrode 32, the wiring 41, the heating resistor 50, and the like, and protects them from abrasion, corrosion, oxidation, and the like. The protective film 52 can be made of an insulating material, for example, amorphous glass. The protective film 52 is formed by thick-film printing using a glass paste and then sintering. The dimension of the protective film 52 in the thickness direction Z is, for example, about 3 to 8 μm.

The protective film 54 covers at least the connection electrode 42. In this embodiment, the protective film 54 covers the protective film 52 and the connection electrode 42, and is in contact with the upper surface of the protective film 52 and the upper surface of the connection electrode 42. The protective film 54 is an outermost protective film that directly rubs against the printing medium, and for example, a protective film containing amorphous glass, Sialon (Sialon), silicon carbide, or silicon nitride as a main component and having a hardness of about 1000 to 2000HK can be used. The dimension of the protective film 54 in the thickness direction Z is, for example, 5 to 8 μm.

Here, a method of manufacturing the thermal head 100A of the present embodiment will be described.

As shown in fig. 3 and 4, first, the substrate 15 is prepared, a glass paste is applied to the substrate 15 by screen printing or the like, the applied glass paste is dried, and then, heat treatment is performed, so that the heat storage layer 33 is formed on the substrate 15. The sintering treatment is carried out at 850 to 1200 ℃ for 1 to 5 hours, for example.

Next, as shown in fig. 5 and 6, a plurality of individual electrodes 31 and a common electrode 32 are formed on the heat storage layer 33. The common electrode 32 includes comb-teeth 32A and a common portion 32B that connects the comb-teeth 32A together. The individual electrodes 31 and the common electrode 32 can be obtained by forming an electrode pattern by applying the above-described metal paste using screen printing or the like.

Next, as shown in fig. 7 and 8, a plurality of wirings 41 in contact with the plurality of individual electrodes 31 are formed. The wiring 41 can be formed by a photolithography process using a metal such as gold or silver.

Next, as shown in fig. 9 and 10, the heating resistors 50 (heating resistor portions 51) are formed on the individual electrodes 31 and on the comb-teeth portions 32A of the common electrode 32 by a thick film forming technique. The heating resistor 50 is formed by supplying a resistor paste using screen printing or a dispenser and sintering it. The resistor paste contains, for example, ruthenium oxide.

Next, as shown in fig. 11 and 12, a protective film 52 is formed to cover the individual electrodes 31, a part of the common electrode 32, the wiring 41, and the heating resistor 50. The protective film 52 is made of, for example, amorphous glass. The protective film 52 is formed by thick-film printing using a glass paste and then sintering.

Next, as shown in fig. 13 and 14, the connection electrode 42 is formed in contact with the common electrode 32. The connection electrode 42 is obtained by applying a metal paste such as silver by using a screen printing method or the like to form an electrode pattern. The protective film 52 suppresses the flow of the metal paste before the metal paste is sintered, and thus the enlargement of the surface area of the connection electrode 42 in contact with the surface of the common electrode 32 can be suppressed by the protective film 52.

Next, as shown in fig. 15 and 16, a protective film 54 is formed to cover at least the connection electrode 42. The protective film 54 is an outermost protective film that directly rubs against the printing medium, and for example, a protective film containing amorphous glass, Sialon (Sialon), silicon carbide, or silicon nitride as a main component and having a hardness of about 1000 to 2000HK can be used. The dimension of the protective film 54 in the thickness direction Z is, for example, 5 to 8 μm.

Through the above steps, the thermal print head of the present embodiment can be manufactured.

In the present embodiment, since the connection electrode 42 is formed after the protective film 52 is formed, the flow of the metal paste can be suppressed by the protective film 52 even before the metal paste is sintered. The protective film 52 can suppress the surface area of the connection electrode 42 in contact with the surface of the common electrode 32 from being enlarged, and can narrow the path through which the material of the connection electrode 42 spreads toward the comb-teeth portion 32A of the common electrode 32. Further, by providing the protective film 52 so as to be in contact with one side surface of the connection electrode 42 in the sub-scanning direction and providing the protective film 54 so as to be in contact with the other side surface of the connection electrode 42 in the sub-scanning direction, it is possible to suppress the connection electrode 42 from being in contact with the comb-teeth portion 32A near the comb-teeth portion 32A of the common electrode 32 in contact with the bottom surface of the protective film 52. Therefore, disconnection of the comb-teeth 32A of the common electrode 32 can be suppressed.

(other embodiments)

The foregoing describes an embodiment with the understanding that the description and drawings forming a part of the disclosure are illustrative and should not be taken to be limiting. Various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art in light of this disclosure. Accordingly, the present embodiment includes various embodiments and the like not described herein.

For example, in a thermal head 100B as a modification of the thermal head 100A, as shown in fig. 17, a connection electrode 42a having a protrusion may be provided instead of the connection electrode 42. Since the fluidity of the metal paste before sintering for forming the connection electrode 42 is high, the metal paste may pass over the protective film 52, and the protruding portion may contact at least a part of the upper surface of the protective film 52.

As in the thermal head 100C shown in fig. 18 and the thermal head 100D shown in fig. 19, the protective film 54 may be configured not to entirely cover but to cover at least the connection electrode 42.

Thermal printer

As shown in fig. 20, the thermal head (for example, the thermal head 100A) according to the present embodiment further includes a substrate 15 (the heat storage layer 33, the individual electrodes 31, the common electrode 32, and the like on the substrate 15 are not shown), a connection substrate 5, a heat dissipation member 8, a driver IC7, a plurality of leads 81, a resin portion 82, and a connector 59. The substrate 15 and the connection substrate 5 are mounted on the heat dissipation member 8 so as to be adjacent to each other in the sub-scanning direction Y. The substrate 15 has a plurality of heat-generating resistive portions 51 arranged in the main scanning direction X. The heat generation resistor 51 is driven by the driver IC7 mounted on the connection board 5 to selectively generate heat. The heating resistor 51 prints on a print medium 92 such as thermal paper pressed against the heating resistor 51 by the platen roller 91 in accordance with a print signal transmitted from the outside through the connector 59.

For example, a printed wiring board can be used as the connection substrate 5. The connection substrate 5 has a structure in which a base material layer and a wiring layer not shown are laminated. The substrate layer can be made of, for example, glass epoxy resin. For example, metals such as copper, silver, palladium, iridium, platinum, and gold can be used for the wiring layer.

The heat dissipation member 8 has a function of releasing heat from the substrate 15. The substrate 15 and the connection substrate 5 are mounted on the heat dissipation member 8. The heat dissipation member 8 can be made of metal such as aluminum, for example.

For example, a conductor such as gold can be used as the lead 81. The lead 81 has a plurality of leads, and a part of each lead is electrically connected to the driver IC7 and each individual electrode by soldering. In addition, some of the other lead wires 81 are soldered to conduct the driver IC7 to the connector 59 via a wiring layer in the connection substrate 5.

The resin portion 82 can be made of, for example, black resin. As the resin portion 82, for example, epoxy resin, silicone resin, or the like can be used. The resin portion 82 covers the driver IC7, the plurality of leads 81, and the like, and protects the driver IC7 and the plurality of leads 81. The connector 59 is fixed to the connection substrate 5. To the connector 59, wiring for supplying power from outside the thermal head to the thermal head and for controlling the drive IC7 are connected.

The thermal printer of the present embodiment may include the thermal head described above. The thermal printer performs printing on a print medium conveyed in the sub-scanning direction Y. Normally, the print medium is fed from the connector 59 side to the heat-generating resistor 51 side. Examples of the print medium include thermal paper used for producing barcode labels and receipts.

The thermal printer includes, for example, a thermal head 100A, a platen roller 91, a main power supply circuit, a measurement circuit, and a control unit. The platen roller 91 faces the thermal head 100A.

The main power supply circuit supplies power to the plurality of heat-generating resistor portions 51 in the thermal head 100A. The measuring circuit measures the resistance value of each of the plurality of heat generating resistor units 51. The measurement circuit measures the resistance value of each of the plurality of heat generation resistor portions 51, for example, when printing is not performed on the print medium. This makes it possible to check the life of the heat-generating resistor 51 and the presence or absence of the heat-generating resistor 51 having failed. The control unit controls the driving states of the main power supply circuit and the measuring circuit. The control unit controls the respective energization states of the plurality of heat generation resistive units 51. The measuring circuit may be omitted.

The connector 59 is used for communication with a device outside the thermal head 100A. The thermal head 100A is electrically connected to a main power supply circuit and a measurement circuit via the connector 59. The thermal head 100A is electrically connected to the control unit via the connector 59.

The drive IC7 receives a signal from the control section via the connector 59. The drive IC7 controls the energization state of each of the plurality of heat-generating resistor units 51 based on the signal received from the control unit. Specifically, the drive IC7 selectively energizes the individual electrodes to cause any one of the heat-generating resistor units 51 to generate heat.

Next, a method of using the thermal printer will be described.

When printing is performed on the print medium, the potential V11 is applied from the main power supply circuit to the connector 59 as the potential V1. In this case, the plurality of heat generation resistor portions 51 selectively generate heat by supplying electricity. By transferring the heat to the printing medium, printing can be performed on the printing medium. As described above, when the potential V11 is applied from the main power supply circuit to the connector 59 as the potential V1, the conduction path for supplying power to each of the plurality of heat-generating resistor units 51 can be secured.

When no printing is performed on the print medium, the resistance value of each of the heat generation resistor portions 51 is measured. At the time of this measurement, no potential is applied from the main power supply circuit to the connector 59. When the resistance value of each heat generation resistor 51 is measured, a potential V12 is applied from the measurement circuit to the connector 59 as a potential V1. In this case, the plurality of heat-generating resistor units 51 are energized sequentially (for example, sequentially from the heat-generating resistor unit 51 located at the end in the main scanning direction X). The measuring circuit measures the resistance value of each heat-generating resistive portion 51 based on the value of the current flowing through the heat-generating resistive portion 51 and the potential v 12. As described above, when the potential V11 is applied from the main power supply circuit to the connector 59 as the potential V1, the current-carrying path for supplying power to each of the plurality of heat-generating resistor units 51 is substantially cut off. This enables the resistance value of each heat generation resistor unit 51 to be measured more accurately by the measuring circuit, and the life of the heat generation resistor unit 51 and the presence or absence of a defective heat generation resistor unit 51 to be checked.

With this embodiment, a thermal printer capable of suppressing disconnection of the comb portion of the common electrode can be obtained.

The present invention relates to the subject matter of Japanese patent application No. 2020-.

Claims

1. A thermal print head, comprising:

a heat storage layer;

a separate electrode on the heat storage layer;

a common electrode having a comb-tooth portion spaced apart from the individual electrode and opposed to the individual electrode;

the independent electrodes and the heating resistor on the comb teeth part;

a connection electrode made of a different material from the common electrode and in contact with the common electrode;

a first protective film covering the heating resistor, the individual electrodes, and a part of the common electrode; and

a second protective film covering the connection electrode,

an end portion of the common electrode in the sub-scanning direction is covered with the connection electrode,

one side surface of the connection electrode in the sub-scanning direction is in contact with the second protective film, and the other side surface of the connection electrode in the sub-scanning direction is in contact with the first protective film.

2. The thermal print head of claim 1, wherein:

the common electrode comprises gold, and the common electrode comprises gold,

the connection electrode includes silver.

3. The thermal print head according to claim 1 or 2, wherein:

further comprising a wiring in contact with the individual electrode,

the connection electrode is thicker than the wiring.

4. A thermal print head according to any one of claims 1 to 3, wherein:

the connection electrode has a protruding portion that,

the protrusion is in contact with at least a portion of an upper surface of the first protection film.

5. The thermal print head according to any one of claims 1 to 4, wherein:

the second protective film covers the first protective film.

6. The thermal print head according to any one of claims 1 to 5, wherein:

the second protective film is in contact with an upper surface of the first protective film and an upper surface of the connection electrode.

7. The thermal print head according to any one of claims 1 to 6, wherein:

the individual electrode is spaced apart from the comb-teeth portion in the main scanning direction.

8. A thermal printer having a thermal head according to any one of claims 1 to 7.

9. A method of manufacturing a thermal print head, comprising:

a heat storage layer is formed on the substrate,

forming an independent electrode and a common electrode having comb teeth on the heat storage layer,

forming a wiring in contact with the individual electrode,

a heating resistor body is formed on the individual electrode and the common electrode,

forming a first protective film covering the heating resistor, the individual electrodes, a part of the common electrode, and the wiring,

forming a connection electrode in contact with another portion of the common electrode after the first protective film is formed,

forming a second protective film covering the connection electrode,

the individual electrodes are spaced apart from and opposed to the comb-teeth portions of the common electrode,

the common electrode is made of a material different from the connection electrode.

10. The method of manufacturing a thermal print head according to claim 9, wherein:

11. The method of manufacturing a thermal print head according to claim 9 or 10, wherein:

the common electrode comprises gold, and the common electrode comprises gold,

the connection electrode includes silver.

12. A method of manufacturing a thermal print head according to any one of claims 9 to 11, wherein:

the connection electrode is thicker than the wiring.

13. The method of manufacturing a thermal print head according to any one of claims 9 to 12, wherein:

the connection electrode has a protruding portion that,

14. The method of manufacturing a thermal print head according to any one of claims 9 to 13, wherein:

the second protective film covers the first protective film.

15. The method of manufacturing a thermal print head according to any one of claims 9 to 14, wherein:

16. The method of manufacturing a thermal print head according to any one of claims 9 to 15, wherein:

the connection electrode is formed by screen printing a metal paste,

the wiring is formed by a photolithography process.