CN116572645A

CN116572645A - Thermal print head, thermal printer, and method of manufacturing thermal print head

Info

Publication number: CN116572645A
Application number: CN202310071383.0A
Authority: CN
Inventors: 中久保一也; 有泷康之
Original assignee: Rohm Co Ltd
Current assignee: Rohm Co Ltd
Priority date: 2022-02-08
Filing date: 2023-02-07
Publication date: 2023-08-11
Also published as: JP2023115544A

Abstract

The invention provides a thermal print head which ensures good printing efficiency during printing. In addition, a thermal printer having the thermal print head is provided. Further, a method for manufacturing a thermal head is provided which ensures good printing efficiency during printing. The thermal print head includes: a heat storage layer; a heating resistor disposed on the heat storage layer; a common electrode disposed on the heat storage layer and having comb teeth; and an individual electrode disposed on the heat storage layer at a distance from the comb-teeth portion of the common electrode and facing the comb-teeth portion, wherein the individual electrode and the comb-teeth portion have a first film thickness portion and a second film thickness portion smaller than the first film thickness portion, respectively, in a thickness direction of the heat storage layer, and the heating resistor is in contact with the second film thickness portion of the individual electrode and the second film thickness portion of the comb-teeth portion.

Description

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

Technical Field

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

Background

The thermal head has a large number of heat generating portions arranged in the main scanning direction on a head substrate, for example. Each heat generating portion is formed by laminating a glaze layer (also referred to as a heat storage layer), a common electrode, an individual electrode, and a resistor layer on a head substrate. By applying current between the common electrode and the individual electrodes, the exposed portion (heat generating portion) of the resistor layer generates heat due to joule heat. Printing on a print medium is completed by transferring the heat to the print medium (thermal paper or the like used for making bar codes or receipts).

Common electrodes, individual electrodes, and the like, and electrode patterns are formed by screen printing (and also performing a photolithography process) a paste of a metal such as gold, silver, or the like. Further, wirings for supplying a voltage from the outside to the common electrode and the individual electrode are respectively in contact with the common electrode and the individual electrode. The wiring is formed by a photolithography process using a metal such as gold or silver. Gold has a high price, and from the viewpoint of reducing the cost of the product, silver has been proposed as a relatively inexpensive metal having excellent conductivity.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2012-121283.

Disclosure of Invention

Problems to be solved by the invention

In order to reduce the influence of disconnection of the common electrode and the individual electrode, and the wiring due to aggregation of silver and diffusion of silver into the protective film when silver is used in the material of the common electrode and the individual electrode, and the wiring, the thickness of the common electrode and the individual electrode, and the wiring is increased as compared with when gold is used in the material. However, when the common electrode and the individual electrode are formed thicker near the heat generating portion, large heat (heat diffusion) from the heat generating portion to the common electrode and the individual electrode becomes larger. Therefore, in order to increase the energy required for the heat generating portion to rise to a predetermined temperature, there is a problem that the printing efficiency (energy efficiency) is lowered when printing on thermal paper or the like.

An object of one embodiment of the present invention is to provide a thermal head, a thermal printer, and a method of manufacturing a thermal head, which can ensure good printing efficiency at the time of printing.

Means for solving the problems

One embodiment of the present invention is a thermal head including: a heat storage layer; a heating resistor disposed on the heat storage layer; a common electrode disposed on the heat storage layer and having comb teeth; and a separate electrode disposed on the heat storage layer, spaced apart from the comb-teeth portion of the common electrode and facing the comb-teeth portion. The individual electrode and the comb teeth have a first film thickness portion and a second film thickness portion smaller than the first film thickness portion, respectively, in a thickness direction of the heat storage layer, and the heating resistor is in contact with the second film thickness portion of the individual electrode and the second film thickness portion of the comb teeth.

Another aspect of the present embodiment is a thermal printer having the thermal head.

In addition, another aspect of the present embodiment is a method for manufacturing a thermal head, in which a heat storage layer is formed, a common electrode and an individual electrode are formed on the heat storage layer so as to have a first film thickness portion and a second film thickness portion, respectively, the common electrode has a comb-teeth portion, the individual electrode is spaced apart from and opposed to the comb-teeth portion, and a heating resistor is formed on the comb-teeth portion and on the individual electrode. The thickness of the second film thickness portion is smaller than that of the first film thickness portion in the thickness direction of the heat storage layer, and the heating resistor is in contact with the second film thickness portion of the individual electrode and the second film thickness portion of the comb-teeth portion.

In addition, another aspect of the present embodiment is a method for manufacturing a thermal head, in which a heat storage layer is formed, a heat generating resistor is formed on the heat storage layer, and a common electrode and an individual electrode are formed on the heat storage layer and the heat generating resistor so as to have a first film thickness portion and a second film thickness portion, respectively, the common electrode having a comb-tooth portion, the individual electrode being spaced apart from and opposed to the comb-tooth portion. The thickness of the second film thickness portion is smaller than that of the first film thickness portion in the thickness direction of the heat storage layer, and the heating resistor is in contact with the second film thickness portion of the individual electrode and the second film thickness portion of the comb-teeth portion.

Effects of the invention

According to the present embodiment, a thermal head, a thermal printer, and a method of manufacturing a thermal head that ensure good printing efficiency at the time of printing can be provided.

Drawings

Fig. 1A is a partial perspective view showing the structure of a thermal head according to an embodiment.

Fig. 1B is a partial cross-sectional view taken along line IB-IB of fig. 1A.

Fig. 1C is a partial cross-sectional view along the IC-IC line of fig. 1A.

FIG. 1D is a partial cross-sectional view taken along the ID-ID line of FIG. 1A.

Fig. 2A is a partial perspective view (one of them) for explaining a method of manufacturing the thermal head of the embodiment.

Fig. 2B is a partial cross-sectional view taken along line IIB-IIB of fig. 2A.

Fig. 2C is a partial cross-sectional view taken along line IIC-IIC of fig. 2A.

Fig. 2D is a partial cross-sectional view taken along the IID-IID line of fig. 2A.

Fig. 3A is a partial perspective view (second) for explaining a method of manufacturing the thermal head according to the embodiment.

Fig. 3B is a partial cross-sectional view taken along line IIIB-IIIB of fig. 3A.

Fig. 3C is a partial cross-sectional view taken along line IIIC-IIIC of fig. 3A.

Fig. 3D is a partial cross-sectional view taken along line IIID-IIID of fig. 3A.

Fig. 4A is a partial perspective view (third) for explaining a method of manufacturing the thermal head according to the embodiment.

Fig. 4B is a partial cross-sectional view taken along line IVB-IVB of fig. 4A.

Fig. 4C is a partial cross-sectional view taken along line IVC-IVC of fig. 4A.

Fig. 4D is a partial cross-sectional view taken along the line IVD-IVD of fig. 4A.

Fig. 5A is a partial perspective view (fourth) for explaining a method of manufacturing the thermal head according to the embodiment.

FIG. 5B is a partial cross-sectional view taken along line VB-VB of FIG. 5A.

Fig. 5C is a partial cross-sectional view along the VC-VC line of fig. 5A.

FIG. 5D is a partial cross-sectional view taken along the VD-VD line of FIG. 5A.

Fig. 6A is a partial perspective view (fifth) for explaining a method of manufacturing the thermal head according to the embodiment.

Fig. 6B is a partial cross-sectional view taken along line VIB-VIB of fig. 6A.

FIG. 6C is a partial cross-sectional view taken along the line VIC-VIC of FIG. 6A.

Fig. 6D is a partial cross-sectional view along the VID-VID line of fig. 6A.

Fig. 7A is a partial perspective view showing the structure of a thermal head according to a first modification of the embodiment.

Fig. 7B is a partial cross-sectional view taken along line VIIB-VIIB of fig. 7A.

Fig. 7C is a partial cross-sectional view taken along line VIIC-VIIC of fig. 7A.

Fig. 7D is a partial cross-sectional view taken along line VIID-VIID of fig. 7A.

Fig. 8A is a partial perspective view showing the structure of a thermal head according to a second modification of the embodiment.

Fig. 8B is a partial cross-sectional view taken along line VIIIB-VIIIB of fig. 8A.

Fig. 8C is a partial cross-sectional view taken along line VIIIC-VIIIC of fig. 8A.

Fig. 8D is a partial cross-sectional view taken along line VIIID-VIIID of fig. 8A.

Fig. 9A is a partial perspective view (one of) for explaining a method of manufacturing a thermal head according to a second modification of the embodiment.

Fig. 9B is a partial cross-sectional view along line IXB-IXB of fig. 9A.

Fig. 9C is a partial cross-sectional view along line IXC-IXC of fig. 9A.

Fig. 9D is a partial cross-sectional view along line IXD-IXD of fig. 9A.

Fig. 10A is a partial perspective view (second) for explaining a method of manufacturing a thermal head according to a second modification of the embodiment.

Fig. 10B is a partial cross-sectional view along the XB-XB line of fig. 10A.

Fig. 10C is a partial cross-sectional view along line XC-XC of fig. 10A.

Fig. 10D is a partial cross-sectional view taken along line XD-XD of fig. 10A.

Fig. 11A is a partial perspective view (third) for explaining a method of manufacturing a thermal head according to a second modification of the embodiment.

FIG. 11B is a partial cross-sectional view taken along line XIB-XIB of FIG. 11A.

FIG. 11C is a partial cross-sectional view along the XIC-XIC line of FIG. 11A.

FIG. 11D is a partial cross-sectional view taken along line XID-XID of FIG. 11A.

Fig. 12A is a partial perspective view (fourth) for explaining a method of manufacturing a thermal head according to a second modification of the embodiment.

Fig. 12B is a partial cross-sectional view taken along line XIIB-XIIB of fig. 12A.

Fig. 12C is a partial cross-sectional view taken along line XIIC-XIIC of fig. 12A.

Fig. 12D is a partial cross-sectional view taken along line XIID-XIID of fig. 12A.

Fig. 13A is a partial perspective view showing the structure of a thermal head according to a third modification of the embodiment.

Fig. 13B is a partial cross-sectional view taken along line XIIIB-XIIIB of fig. 13A.

Fig. 13C is a partial cross-sectional view along line XIIIC-XIIIC of fig. 13A.

Fig. 13D is a partial cross-sectional view taken along line XIIID-XIIID of fig. 13A.

Fig. 14 is a sectional view showing the structure of the thermal head.

Description of the reference numerals

5 connection substrate

7 drive IC

8 radiating component

15 substrate

31 individual electrodes

31a, 32a first electrode layer

31b, 32b second electrode layer

32 common electrode

32A comb teeth part

32B public part

33 heat storage layer

34 protective film

40 heating resistor

41 heating resistor part

59 connector

81 lead

82 resin part

91 platen roller

92 print medium

100. 100A, 100B, 100C thermal printheads.

Detailed Description

Next, this embodiment will be described with reference to the drawings. In the description of the drawings described below, the same or similar reference numerals are given to the same or similar parts. However, the drawings are schematic, and it should be noted that the relationship between the thickness and the planar dimension of each component may be different from the relationship between the actual thickness and the planar dimension. Accordingly, the specific thickness and dimensions should be determined with reference to the following description. The drawings include, of course, portions having different dimensional relationships and ratios from each other.

The embodiments described below are embodiments illustrating an apparatus or a method for embodying the technical idea, and are not intended to specify the material, shape, structure, arrangement, and the like of each constituent member. The present embodiment can be variously modified within the scope of the present invention.

One embodiment of the present embodiment is described below.

<1> a thermal printhead, comprising: a heat storage layer; a heating resistor disposed on the heat storage layer; a common electrode disposed on the heat storage layer and having a comb-tooth portion; and an individual electrode disposed on the heat storage layer at a distance from the comb-teeth portion of the common electrode and facing the comb-teeth portion, wherein the individual electrode and the comb-teeth portion each have a first film thickness portion and a second film thickness portion smaller than the first film thickness portion in a thickness direction of the heat storage layer, and the heating resistor is in contact with the second film thickness portion of the individual electrode and the second film thickness portion of the comb-teeth portion.

<2> the thermal head according to <1>, wherein the heating resistor is disposed on the individual electrode and the comb teeth at a contact portion between the heating resistor and the individual electrode and the comb teeth.

<3> the thermal head according to <1>, wherein the individual electrode and the common electrode are disposed on the heating resistor at a contact portion between the heating resistor and the individual electrode and the comb teeth.

Based on <1> to <3>, disconnection due to aggregation of the metal contained in the metal paste can be suppressed at the time of forming the individual electrode and the common electrode (at the time of firing). Further, the resistances of the individual electrodes and the common electrode can be reduced. Further, since the film thicknesses of the individual electrode and the common electrode in the region overlapping the heating resistor are small, heat conduction from the heating resistor to the individual electrode and the common electrode can be reduced, and an increase in energy required for raising the heating resistor to a predetermined temperature can be suppressed. Therefore, good printing efficiency can be ensured.

<4> the thermal head according to any one of <1> to <3>, wherein the common electrode further has a common portion connected to the comb teeth portion, and a film thickness of the common portion is equal to a film thickness of the first film thickness portion.

Based on <4>, the resistance of the common portion can be reduced, and disconnection due to aggregation of metals can be suppressed.

<5> the thermal head according to any one of <1> to <4>, wherein the material of the individual electrode and the material of the common electrode contain silver or gold.

Based on <5>, a separate electrode and a common electrode having good metal characteristics and ionization tendency can be obtained.

The thermal head according to any one of <1> to <5>, further comprising a substrate, wherein the heat storage layer is disposed on an upper surface of the substrate, and the substrate is made of ceramic.

Based on <6>, a substrate having sufficient heat dissipation properties can be used for the thermal head.

<7> a thermal printer having the thermal print head of any one of <1> to <6 >.

Based on <7>, a thermal printer ensuring good printing efficiency can be obtained.

<8> a method for manufacturing a thermal head, wherein a heat storage layer is formed, on which a common electrode and an individual electrode are formed to have a first film thickness portion and a second film thickness portion, respectively, wherein the common electrode has a comb-tooth portion, the individual electrode is spaced apart from and opposed to the comb-tooth portion, a heat generating resistor is formed on the comb-tooth portion and the individual electrode, the film thickness of the second film thickness portion is smaller than the film thickness of the first film thickness portion in the thickness direction of the heat storage layer, and the heat generating resistor is in contact with the second film thickness portion of the individual electrode and the second film thickness portion of the comb-tooth portion.

<9> the method for manufacturing a thermal head according to <8>, wherein the forming of the individual electrode and the common electrode comprises: forming a first electrode layer on the heat storage layer; and forming a second electrode layer on the first electrode layer except for a region overlapping the heating resistor in a thickness direction of the heat storage layer, wherein a film thickness of the first film thickness portion is a sum of a film thickness of the first electrode layer and a film thickness of the second electrode layer, and a film thickness of the second film thickness portion is a film thickness of the first electrode layer.

<10> the method for manufacturing a thermal head according to <8>, wherein the forming of the individual electrode and the common electrode comprises: forming a first electrode layer on the heat storage layer except for a region overlapping with the heating resistor in a thickness direction of the heat storage layer; and forming a second electrode layer on the first electrode layer and on the heat storage layer in a region overlapping the heat generating resistor, wherein the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer and the film thickness of the second electrode layer, and the film thickness of the second film thickness portion is the film thickness of the second electrode layer.

<11> a method for manufacturing a thermal head, wherein a heat storage layer is formed, a heat generating resistor is formed on the heat storage layer, a common electrode and an individual electrode are formed on the heat storage layer and the heat generating resistor so as to have a first film thickness portion and a second film thickness portion, respectively, wherein the common electrode has a comb-tooth portion, the individual electrode is spaced apart from and opposed to the comb-tooth portion, a film thickness of the second film thickness portion is smaller than a film thickness of the first film thickness portion in a thickness direction of the heat storage layer, and the heat generating resistor is in contact with the second film thickness portion of the individual electrode and the second film thickness portion of the comb-tooth portion.

<12> the method for manufacturing a thermal head according to <11>, wherein the forming of the individual electrode and the common electrode comprises: forming a first electrode layer on the heat storage layer except for a region overlapping with the heating resistor in a thickness direction of the heat storage layer; and forming a second electrode layer on the first electrode layer and the heating resistor, wherein the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer and the film thickness of the second electrode layer, and the film thickness of the second film thickness portion is the film thickness of the second electrode layer.

<13> the method for manufacturing a thermal head according to <11>, wherein the forming of the individual electrode and the common electrode comprises: forming a first electrode layer on the heat storage layer and on the heating resistor; and forming a second electrode layer on the first electrode layer except for a region overlapping the heating resistor in a thickness direction of the heat storage layer, wherein a film thickness of the first film thickness portion is a sum of a film thickness of the first electrode layer and a film thickness of the second electrode layer, and a film thickness of the second film thickness portion is a film thickness of the first electrode layer.

Based on <8> to <13>, disconnection due to aggregation of the metal contained in the metal paste can be suppressed at the time of forming the individual electrode and the common electrode (at the time of firing). Further, the resistances of the individual electrodes and the common electrode can be reduced. Further, since the film thicknesses of the individual electrode and the common electrode in the region overlapping the heating resistor are small, heat conduction from the heating resistor to the individual electrode and the common electrode can be reduced, and an increase in energy required for raising the heating resistor to a predetermined temperature can be suppressed. Therefore, good printing efficiency can be ensured.

< thermal print head >

The thermal head 100 of the present embodiment will be described with reference to the drawings.

Fig. 1A is a partial perspective view showing a thermal head 100. Fig. 1B is a partial cross-sectional view taken along line IB-IB of fig. 1A. Fig. 1C is a partial cross-sectional view along the IC-IC line of fig. 1A. FIG. 1D is a partial cross-sectional view taken along the ID-ID line of FIG. 1A. Fig. 1A to 1D show a part of a thermal printer (corresponding to 1 thermal head) having a plurality of thermal heads, and in the present embodiment, the 1 thermal heads are regarded as a single thermal head 100. The thermal head 100 includes: a substrate 15 as an insulator; a heat storage layer 33 on the substrate 15; a common electrode 32 disposed on the heat storage layer 33 and having comb teeth 32A; individual electrodes 31 arranged on the heat storage layer 33, spaced apart from the comb-teeth portions 32A of the common electrode 32, and facing the comb-teeth portions 32A; heating resistors 40 on the heat storage layer 33, on the individual electrode 31, and on the common electrode 32; and a protective film 34 covering the individual electrode 31, the common electrode 32, and the heat generating resistor 40. Fig. 1A omits illustration of the protective film 34 for ease of understanding.

The individual electrode 31 includes a first electrode layer 31a and a second electrode layer 31b disposed on the first electrode layer 31a except for a region overlapping the heat generating resistor 40 in a thickness direction Z described later. The common electrode 32 includes a first electrode layer 32a and a second electrode layer 32b disposed on the first electrode layer 32a except for a region overlapping the heat generating resistor 40 in the thickness direction Z. In the present embodiment, the portion where the first electrode layer 31a and the second electrode layer 31b are stacked in the thickness direction Z of the heat storage layer 33 is referred to as a first film thickness portion of the individual electrode 31, and the portion where only the first electrode layer 31a is referred to as a second film thickness portion of the individual electrode 31. In the present embodiment, the portion where the first electrode layer 32A and the second electrode layer 32b are stacked in the thickness direction Z of the heat storage layer 33 is referred to as a first film thickness portion of the common electrode 32 (including the comb teeth portion 32A, etc.), and the portion where only the first electrode layer 32A is referred to as a second film thickness portion of the common electrode 32. That is, in the individual electrode 31, the film thickness of the second film thickness portion is smaller than that of the first film thickness portion. In the common electrode 32, the film thickness of the second film thickness portion is smaller than that of the first film thickness portion. The heating resistor 40 is in contact with the second film thickness portion of the individual electrode 31 and the second film thickness portion of the comb-teeth portion 32A that is a part of the common electrode 32.

The heat generating resistor 40 includes a plurality of heat generating resistor portions 41 that generate heat due to the current flowing through the individual electrode 31 and the common electrode 32. Each of the heat generating resistor portions 41 is formed independently between the individual electrode 31 and the common electrode 32. Fig. 1A omits illustration of the plurality of heat generating resistor portions 41. The plurality of heating resistor units 41 are arranged linearly on the heat storage layer 33.

The heating resistor 40 is electrically connected to the individual electrode 31 and the common electrode 32, and generates heat at a portion where current flows from the individual electrode 31 and the common electrode 32. Specifically, the heat generating resistor 40 (heat generating resistor 41) is selectively heated by independently applying a heat generating voltage according to a print signal transmitted from the outside to the drive IC or the like. The heat generating resistor 41 is independently energized according to the print signal, and selectively generates heat. Printing dots are formed by the heat generation in this way. At the contact portion between the heating resistor 40 and the individual electrode 31 and the common electrode 32 (comb teeth 32A), the heating resistor 40 is disposed on the individual electrode 31 and the common electrode 32 (comb teeth 32A). As the heating resistor 40, a material having higher resistivity than the material constituting the individual electrode 31 and the common electrode 32, for example, ruthenium oxide or the like can be used.

In the present embodiment, the longitudinal direction in which the heat generating resistor 40 linearly extends is referred to as the main scanning direction X, the direction perpendicular to the main scanning direction X and parallel to the upper surface of the substrate 15 is referred to as the sub-scanning direction Y, and the direction corresponding to the thickness of the substrate 15 or the like is referred to as the thickness direction Z. In other words, the thickness direction Z is a direction perpendicular to each of the main scanning direction X and the sub scanning direction Y. The direction in which the heat storage layer 33 is located is upward as viewed from the substrate 15, and the direction in which the substrate 15 is located is downward as viewed from the heat storage layer 33.

In this specification, the term "electrically connected" includes a case where the electrically connected element is connected via a "certain element having an electrical function". Here, the "certain member having an electric function" is not particularly limited as long as it is a member capable of delivering an electric signal between the connection objects. For example, the "certain component having an electric function" includes an electrode, a wiring, a switching element, a resistive element, an inductor, a capacitive element, an element having other various functions, and the like.

The substrate 15 is an insulator, and is made of, for example, ceramic or single crystal semiconductor. As the ceramic, for example, alumina or the like can be used. As the single crystal semiconductor substrate, a silicon substrate or the like can be used, for example. From the viewpoint of heat dissipation, alumina having relatively high thermal conductivity is preferably used for the substrate 15.

A heat storage layer 33 (also referred to as a glaze layer) having a function of storing heat is laminated on the substrate 15. The heat storage layer 33 stores heat generated from a heat generating resistor 41 described later. As the heat storage layer 33, an insulating material can be used, and for example, silicon oxide or silicon nitride, which is a main component of glass, can be used for the heat storage layer 33. The dimension of the heat storage layer 33 in the thickness direction Z is not particularly limited, and is, for example, 5 to 200 μm, preferably 10 to 30 μm.

An individual electrode 31 and a common electrode 32 formed of a metal paste are provided on the heat storage layer 33. The individual electrode 31 and the common electrode 32 are obtained by applying a metal paste, which is a material of the individual electrode 31 and a material of the common electrode 32, to the heat storage layer 33 by screen printing or the like, followed by firing, and forming an electrode pattern. In addition, a photolithography process may be performed to form the individual electrode 31 and the common electrode 32 in addition to screen printing.

As the metal paste, for example, a paste containing metal particles of copper, silver, palladium, iridium, platinum, gold, or the like can be used. In addition, an organometallic compound can be used as the metal paste. Silver and gold are preferable from the viewpoint of the characteristics of the metal and the ionization tendency, and silver is more preferable from the viewpoint of the characteristics of the metal, the ionization tendency and the cost reduction. The solvent contained in the metal paste has a function of uniformly dispersing the metal particles, and examples thereof include 1 or a mixture of 2 or more of an ester solvent, a ketone solvent, a glycol ether solvent, an aliphatic solvent, an alicyclic solvent, an aromatic solvent, an alcohol solvent, and water, but are not limited thereto.

Examples of the ester solvents include ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, amyl 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. Glycol ether solvents such as ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether and the like, and acetic acid esters 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, or acetic acid esters of these monoethers.

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 (other than the glycol ether solvents described above) include ethanol, propanol, butanol, and the like.

The metal paste may contain a dispersant, a surface treatment agent, an anti-friction enhancing agent, an infrared ray absorber, an ultraviolet ray absorber, an aromatic agent, an oxidation inhibitor, an organic pigment, an inorganic pigment, a defoaming 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 electrode 31 has a first electrode layer 31a and a second electrode layer 31b. The common electrode 32 has a first electrode layer 32a and a second electrode layer 32b. The first electrode layer 31a and the first electrode layer 32a are preferably formed using a paste containing metal particles having a smaller particle diameter than the second electrode layer 31b and the second electrode layer 32b, for example, a resin paste containing silver is preferably used. The dimensions of the first electrode layer 31a and the first electrode layer 32a in the thickness direction Z are not particularly limited, and are, for example, 1 to 3 μm, preferably 1.5 to 2.5 μm.

The second electrode layer 31b is disposed on a part of the first electrode layer 31a, specifically, on the first electrode layer 31a except for a region overlapping with a heat generating resistor 40 described later in the thickness direction Z. The second electrode layer 32b is disposed on a part of the first electrode layer 32a, specifically, on the first electrode layer 32a except for a region overlapping with a heat generating resistor 40 described later in the thickness direction Z. The second electrode layer 31b and the second electrode layer 32b are preferably formed using a paste containing metal particles having a larger particle diameter than the metal particles contained in the paste used for forming the first electrode layer 31a and the first electrode layer 32a, and for example, are preferably formed of a resin paste containing silver particles. The dimensions of the second electrode layer 31b and the second electrode layer 32b in the thickness direction Z are not particularly limited, and are, for example, 1 to 5 μm, preferably 2 to 4 μm.

The metal particles contained in the paste used for forming the first electrode layer 31a and the first electrode layer 32a have a smaller particle diameter than the metal particles contained in the paste used for forming the second electrode layer 31b and the second electrode layer 32 b. Therefore, the average surface roughness of the first electrode layer 31a and the first electrode layer 32a is smaller than the average surface roughness of the second electrode layer 31b and the second electrode layer 32 b. Average surface roughness is, for example, in accordance with JIS B0601: 2013 or ISO 25178.

The electrode layer having a large average surface roughness is preferably disposed on the upper side in contact with the wire or the like, because bonding characteristics such as adhesion are improved. That is, by disposing the second electrode layer 31b and the second electrode layer 32b having relatively large average surface roughness on the first electrode layer 31a and the first electrode layer 32a having relatively small average surface roughness, the contact range between the wire of the individual pad portion and the second electrode layer 31b or the second electrode layer 32b, which are not shown, is widened, and the bonding characteristics are improved.

In the individual electrode 31, the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer 31a and the film thickness of the second electrode layer 31b, and the film thickness of the second film thickness portion is the film thickness of the first electrode layer 31 a. In the common electrode 32, the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer 32a and the film thickness of the second electrode layer 32b, and the film thickness of the second film thickness portion is the film thickness of the first electrode layer 32 a. In the case where it is difficult to determine the boundary, for example, when the first electrode layer 31a and the second electrode layer 31b are made of the same material, a portion separated from the upper surface of the second electrode layer 31b by the film thickness of the second electrode layer 31b is defined as the boundary surface between the first electrode layer 31a and the second electrode layer 31 b. When it is difficult to determine the boundary, for example, when the first electrode layer 32a and the second electrode layer 32b are made of the same material, a portion separated from the upper surface of the second electrode layer 32b by the film thickness of the second electrode layer 32b is defined as the boundary surface between the first electrode layer 32a and the second electrode layer 32 b.

The first film thickness portion of the individual electrode 31 is larger than the film thickness of the second film thickness portion of the individual electrode 31, and the first film thickness portion of the common electrode 32 is larger than the film thickness of the second film thickness portion of the common electrode 32. Therefore, when the individual electrode 31 and the common electrode 32 are formed (at the time of firing), disconnection due to aggregation of the metal contained in the metal paste can be suppressed. Further, the resistances of the individual electrode 31 and the common electrode 32 can be reduced. The second film thickness portion of the individual electrode 31 and the second film thickness portion of the common electrode 32, which are regions overlapping the heat generating resistor 40 described later, are smaller than the film thicknesses of the first film thickness portion of the individual electrode 31 and the first film thickness portion of the common electrode 32, respectively. Therefore, the heat conduction from the heating resistor 40 to the individual electrode 31 and the common electrode 32 can be made small, and an increase in energy required for raising the heating resistor 40 to a predetermined temperature can be suppressed. Therefore, good printing efficiency can be ensured.

The individual electrodes 31 are formed in a stripe shape extending substantially in the sub-scanning direction Y, and the individual electrodes 31 are not electrically connected to each other. Therefore, when the printer incorporating the thermal head is used, the individual electrodes 31 can be independently given different potentials from each other. Individual pad portions, not shown, are connected to the end portions of the individual electrodes 31.

The common electrode 32 is a portion that becomes electrically reverse in polarity to the plurality of individual electrodes 31 when the printer incorporating the thermal head is used. The common electrode 32 has comb-teeth portions 32A and common portions 32B connected to the comb-teeth portions 32A. The common portion 32B is formed along an edge of the upper side of the substrate 15 in the main scanning direction X. In the sub-scanning direction Y, the direction in which the common portion 32B of the common electrode 32 is seen from the individual electrode 31 is the upper side of the sub-scanning direction Y. Each comb tooth portion 32A is formed in a belt shape extending in the sub-scanning direction Y. The tips of the comb teeth 32A are opposed to the tips of the individual electrodes 31 at predetermined intervals along the sub-scanning direction Y. By forming the structure as described above, the pitch of the heating resistors 40 can be narrowed, and high-definition printing can be realized.

The heating resistor 40 can be formed by firing a resistor paste. In the present embodiment, the dimension of the heating resistor 40 in the thickness direction Z is, for example, about 1 to 10 μm.

The heating resistor 40 and the like are covered with the protective film 34, and the protective film 34 protects the heating resistor 40 and the like from abrasion, corrosion, oxidation, and the like. The protective film 34 can be made of an insulating material, for example, amorphous glass. The protective film 34 is formed by thick film printing of a glass paste and firing. The dimension of the protective film 34 in the thickness direction Z is, for example, about 2 to 8 μm. If the thickness is in this range, the thermal head 100 can be obtained which can suppress pressure failure and maintain good printing quality.

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

As shown in fig. 2A to 2D, first, a substrate 15 is prepared, and a heat storage layer 33 is formed on the substrate 15.

The heat storage layer 33 is formed by applying a glass paste to the substrate 15 by screen printing or the like, drying the applied glass paste, and then performing firing treatment. The firing treatment is carried out, for example, at 800 to 1200 ℃ for 10 minutes to 1 hour. The dimension of the heat storage layer 33 in the thickness direction Z is, for example, 25 μm.

Next, as shown in fig. 3A to 3D, the first electrode layer 31a of the individual electrode 31 and the first electrode layer 32a of the common electrode 32 are formed on the heat storage layer 33. The first electrode layer 31a and the first electrode layer 32a are obtained by applying a metal paste having a relatively small particle diameter to the heat storage layer 33 by screen printing or the like, firing the paste, and performing a photolithography step. The dimensions of the first electrode layer 31a and the first electrode layer 32a in the thickness direction Z are, for example, 1 to 3 μm.

Next, as shown in fig. 4A to 4D, the second electrode layer 31b is formed on the first electrode layer 31a except for the region overlapping with the heat generating resistor 40 formed later, and the second electrode layer 32b is formed on the first electrode layer 32a except for the region overlapping with the heat generating resistor 40. The second electrode layer 31b and the second electrode layer 32b are obtained by applying a paste containing metal particles having a larger particle diameter than those of the metal particles contained in the paste used for forming the first electrode layer 31a and the first electrode layer 32a to the first electrode layer 31a and the first electrode layer 32a by screen printing or the like, then firing the paste, and performing a photolithography step. The dimensions of the second electrode layer 31b and the second electrode layer 32b in the thickness direction Z are, for example, 1 to 5 μm.

Through the above steps, the individual electrode 31 can be formed to have the first film thickness portion, which is the portion where the first electrode layer 31a and the second electrode layer 31b are stacked, and the second film thickness portion, which is the portion where only the first electrode layer 31a is stacked. In addition, the common electrode 32 can be formed to have a first film thickness portion which is a portion where the first electrode layer 32a and the second electrode layer 32b are stacked, and a second film thickness portion which is a portion where only the first electrode layer 32a is formed.

Further, the forming method of the individual electrode 31 and the common electrode 32 is not limited to the above-described method. For example, the first metal paste forming the first electrode layer 31a and the first electrode layer 32a is applied on the substrate 15 by screen printing or the like, and the second metal paste forming the second electrode layer 31b and the second electrode layer 32b is applied on the metal paste forming the first electrode layer 31a and the first electrode layer 32a by screen printing or the like. Thereafter, the first metal paste and the second metal paste are fired together and subjected to a photolithography process, and the individual electrode 31 and the common electrode 32 can be formed. Further, a part of the region of the electrode layer 1 (the region overlapping the heat generating resistor 40 to be formed later) may be removed by etching or the like to form the individual electrode 31 and the common electrode 32 having the first film thickness portion and the second film thickness portion.

Next, as shown in fig. 5A to 5D, a resistor paste serving as the heat generating resistor 40 (heat generating resistor 41) is formed. The resistor paste contains ruthenium oxide, for example. Next, the resistor paste is fired to form the heating resistor 40 (heating resistor 41).

Next, as shown in fig. 6A to 6D, a protective film 34 is formed. The protective film 34 is made of amorphous glass, for example. The protective film 34 is formed by firing a thick film printed glass paste.

Through the above steps, the thermal head 100 of the present embodiment can be manufactured.

According to the present embodiment, when the individual electrode 31 and the common electrode 32 are formed (at the time of firing), disconnection due to aggregation of the metal contained in the metal paste can be suppressed. Further, the resistances of the individual electrode 31 and the common electrode 32 can be reduced. Further, since the film thicknesses of the individual electrode 31 and the common electrode 32 in the region overlapping the heating resistor 40 are small, the heat conduction from the heating resistor 40 to the individual electrode 31 and the common electrode 32 can be reduced, and an increase in energy required for raising the heating resistor 40 to a predetermined temperature can be suppressed. Therefore, good printing efficiency can be ensured.

< first modification >

The structure of the thermal head 100A of the present modification will be described.

Fig. 7A is a partial perspective view showing the thermal head 100A. Fig. 7B is a partial cross-sectional view taken along line VIIB-VIIB of fig. 7A. Fig. 7C is a partial cross-sectional view taken along line VIIC-VIIC of fig. 7A. Fig. 7D is a partial cross-sectional view taken along line VIID-VIID of fig. 7A. The thermal head 100A includes: a substrate 15 as an insulator; a heat storage layer 33 on the substrate 15; a common electrode 32 disposed on the heat storage layer 33 and having comb teeth 32A; individual electrodes 31 arranged on the heat storage layer 33, spaced apart from the comb-teeth portions 32A of the common electrode 32, and facing the comb-teeth portions 32A; heating resistors 40 on the heat storage layer 33, on the individual electrode 31, and on the common electrode 32; and a protective film 34 covering the individual electrode 31, the common electrode 32, and the heat generating resistor 40. Fig. 7A omits illustration of the protective film 34 for easy understanding.

The individual electrode 31 has a first electrode layer 31a and a second electrode layer 31b on the first electrode layer 31 a. The common electrode 32 has a first electrode layer 32a and a second electrode layer 32b on the first electrode layer 32 a. In the present modification, the portion where the first electrode layer 31a and the second electrode layer 31b are stacked in the thickness direction Z of the heat storage layer 33 is referred to as a first film thickness portion of the individual electrode 31, and the portion where only the second electrode layer 31b is referred to as a second film thickness portion of the individual electrode 31. In this modification, the portion where the first electrode layer 32A and the second electrode layer 32b are stacked in the thickness direction Z of the heat storage layer 33 is referred to as a first film thickness portion of the common electrode 32 (including the comb-teeth portion 32A, etc.), and the portion where only the second electrode layer 32b is referred to as a second film thickness portion of the common electrode 32. The heating resistor 40 is in contact with the second film thickness portion of the individual electrode 31 and the second film thickness portion of the comb-teeth portion 32A that is a part of the common electrode 32. The thermal head 100A of the present modification differs from the thermal head 100 shown in fig. 1A to 1D described above in that the second film thickness portion of the individual electrode 31 is constituted by only the portion of the second electrode layer 31b, and the second film thickness portion of the common electrode 32 is constituted by only the portion of the second electrode layer 32b. In this modification, points common to the thermal head 100 shown in fig. 1A to 1D are referred to as the above description, and different points are described below.

The individual electrode 31 has a first electrode layer 31a and a second electrode layer 31b. The common electrode 32 has a first electrode layer 32a and a second electrode layer 32b. The first electrode layer 31a and the first electrode layer 32a are disposed on the heat storage layer 33 at least in a part other than the region overlapping the heating resistor 40. The second electrode layer 31b is disposed on the first electrode layer 31a and on the heat storage layer 33 in the region overlapping the heating resistor 40. The second electrode layer 32b is disposed on the first electrode layer 32a and on the heat storage layer 33 in the region overlapping the heating resistor 40. Since the heating resistor 40 is in contact with the second electrode layer 31b and the second electrode layer 32b having a large average surface roughness, the contact range between the heating resistor 40 and the second electrode layer 31b or the second electrode layer 32b is widened, and good adhesion can be obtained in contact with them.

In the individual electrode 31 of the present modification, the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer 31a and the film thickness of the second electrode layer 31b, and the film thickness of the second film thickness portion is the film thickness of the second electrode layer 31b. In the common electrode 32 in this modification, the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer 32a and the film thickness of the second electrode layer 32b, and the film thickness of the second film thickness portion is the film thickness of the second electrode layer 32b.

According to this modification, disconnection due to aggregation of the metal contained in the metal paste can be suppressed when the individual electrode 31 and the common electrode 32 are formed (at the time of firing). Further, the resistances of the individual electrode 31 and the common electrode 32 can be reduced. Further, since the film thicknesses of the individual electrode 31 and the common electrode 32 in the region overlapping the heating resistor 40 are small, the heat conduction from the heating resistor 40 to the individual electrode 31 and the common electrode 32 can be reduced, and an increase in energy required for raising the heating resistor 40 to a predetermined temperature can be suppressed. Therefore, good printing efficiency can be ensured.

< second modification >

The structure of the thermal head 100B of the present modification will be described.

Fig. 8A is a partial perspective view showing the thermal head 100B. Fig. 8B is a partial cross-sectional view taken along line VIIIB-VIIIB of fig. 8A. Fig. 8C is a partial cross-sectional view taken along line VIIIC-VIIIC of fig. 8A. Fig. 8D is a partial cross-sectional view taken along line VIIID-VIIID of fig. 8A. The thermal head 100B includes: a substrate 15 as an insulator; a heat storage layer 33 on the substrate 15; a heating resistor 40 on the heat storage layer 33; a common electrode 32 having comb teeth 32A on the heat storage layer 33 and on the heating resistor 40; individual electrodes 31 on the heat storage layer 33 and on the heating resistor 40, which are spaced apart from the comb-teeth portions 32A of the common electrode 32 and are opposed to the comb-teeth portions 32A; and a protective film 34 covering the heat storage layer 33, the heating resistor 40, the individual electrode 31, and the common electrode 32. Fig. 8A omits illustration of the protective film 34 for easy understanding. The thermal head 100B of the present modification differs from the thermal head 100 shown in fig. 1A to 1D described above in that a part of the individual electrode 31 and a part of the common electrode 32 are arranged on the heat generating resistor 40. In this modification, points common to the thermal head 100 shown in fig. 1A to 1D are referred to as the above description, and different points are described below.

The individual electrode 31 is disposed on the heat storage layer 33 and the heating resistor 40, and has a first electrode layer 31a and a second electrode layer 31b. The common electrode 32 is disposed on the heat storage layer 33 and the heating resistor 40, and includes a first electrode layer 32a and a second electrode layer 32b. The first electrode layer 31a and the first electrode layer 32a are disposed on the heat storage layer 33 and on the heating resistor 40. The second electrode layer 31b is disposed on the first electrode layer 31a except for a region overlapping with the heating resistor 40. The second electrode layer 32b is disposed on the first electrode layer 32a except for the region overlapping with the heating resistor 40.

In the individual electrode 31 in the present modification, the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer 31a and the film thickness of the second electrode layer 31b, and the film thickness of the second film thickness portion is the film thickness of the first electrode layer 31 a. In the common electrode 32 of the present modification, the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer 32a and the film thickness of the second electrode layer 32b, and the film thickness of the second film thickness portion is the film thickness of the first electrode layer 32 a.

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

First, as shown in fig. 2A to 2D, a substrate 15 is prepared, and a heat storage layer 33 is formed on the substrate 15. Next, as shown in fig. 9A to 9D, a resistor paste serving as a heating resistor 40 (heating resistor 41) is formed on the heat storage layer 33. The resistor paste contains ruthenium oxide, for example. Next, the resistor paste is fired to form the heating resistor 40 (heating resistor 41).

Next, as shown in fig. 10A to 10D, the first electrode layer 31a of the individual electrode 31 and the first electrode layer 32a of the common electrode 32 are formed on the heat storage layer 33 and on the heat generating resistor 40. The first electrode layer 31a and the first electrode layer 32a can be obtained by applying the metal paste having the small particle diameter to the heat storage layer 33 and the heating resistor 40 by screen printing or the like, firing the metal paste, and performing a photolithography process. The dimensions of the first electrode layer 31a and the first electrode layer 32a in the thickness direction Z are, for example, 1 to 3 μm.

Next, as shown in fig. 11A to 11D, the second electrode layer 31b is formed on the first electrode layer 31A except for the region overlapping with the heat generating resistor 40, and the second electrode layer 32b is formed on the first electrode layer 32a except for the region overlapping with the heat generating resistor 40. The second electrode layer 31b and the second electrode layer 32b are obtained by applying a paste containing metal particles having a larger particle diameter than those of the metal particles contained in the paste used for forming the first electrode layer 31a and the first electrode layer 32a to the first electrode layer 31a and the first electrode layer 32a by screen printing or the like, firing the paste, and performing a photolithography step. The dimensions of the second electrode layer 31b and the second electrode layer 32b in the thickness direction Z are, for example, 1 to 5 μm.

By the above steps, the individual electrode 31 having the first film thickness portion which is the portion where the first electrode layer 31a and the second electrode layer 31b are stacked and the second film thickness portion which is the portion where only the first electrode layer 31a is formed can be formed, and the common electrode 32 having the first film thickness portion which is the portion where the first electrode layer 32a and the second electrode layer 32b are stacked and the second film thickness portion which is the portion where only the first electrode layer 32a is formed can be formed.

Next, as shown in fig. 12A to 12D, a protective film 34 is formed. The protective film 34 is made of amorphous glass, for example. The protective film 34 is formed by thick film printing of a glass paste and firing the same.

Through the above steps, the thermal head 100B of the present embodiment can be manufactured.

< third modification example >

The structure of the thermal head 100C of the present modification will be described.

Fig. 13A is a partial perspective view showing the thermal head 100C. Fig. 13B is a partial cross-sectional view taken along line XIIIB-XIIIB of fig. 13A. Fig. 13C is a partial cross-sectional view along line XIIIC-XIIIC of fig. 13A. Fig. 13D is a partial cross-sectional view taken along line XIIID-XIIID of fig. 13A. The thermal head 100C includes: a substrate 15 as an insulator; a heat storage layer 33 on the substrate 15; a heating resistor 40 on the heat storage layer 33; a common electrode 32 having comb teeth 32A on the heat storage layer 33 and on the heating resistor 40; individual electrodes 31 on the heat storage layer 33 and on the heating resistor 40, which are spaced apart from the comb-teeth portions 32A of the common electrode 32 and are opposed to the comb-teeth portions 32A; and a protective film 34 covering the heat storage layer 33, the heating resistor 40, the individual electrode 31, and the common electrode 32. Fig. 13A omits illustration of the protective film 34 for easy understanding. The thermal head 100C of the present modification differs from the thermal head 100A shown in fig. 7A to 7D described above in that a part of the individual electrode 31 and a part of the common electrode 32 are arranged on the heat generating resistor 40. In this modification, the above description is given to the points common to the thermal head 100A shown in fig. 7A to 7D, and the following description will be given regarding the differences.

The individual electrode 31 is disposed on the heat storage layer 33 and the heating resistor 40, and has a first electrode layer 31a and a second electrode layer 31b. The common electrode 32 is disposed on the heat storage layer 33 and the heating resistor 40, and includes a first electrode layer 32a and a second electrode layer 32b. In this modification, the portion where the first electrode layer 31a and the second electrode layer 31b are stacked in the thickness direction Z of the heat storage layer 33 is referred to as a first film thickness portion of the individual electrode 31, and the portion where only the second electrode layer 31b is referred to as a second film thickness portion of the individual electrode 31. In this modification, the portion where the first electrode layer 32A and the second electrode layer 32b are stacked in the thickness direction Z of the heat storage layer 33 is referred to as a first film thickness portion of the common electrode 32 (including the comb teeth portion 32A, etc.), and the portion where only the second electrode layer 32b is referred to as a second film thickness portion of the common electrode 32. The heating resistor 40 is in contact with the second film thickness portion of the individual electrode 31 and the second film thickness portion of the comb-teeth portion 32A that is a part of the common electrode 32. Since the heating resistor 40 is in contact with the second electrode layer 31b and the second electrode layer 32b having a large average surface roughness, the contact range between the heating resistor 40 and the second electrode layer 31b or the second electrode layer 32b is widened, and good adhesion can be obtained in contact with them.

In the individual electrode 31 of the present modification, the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer 31a and the film thickness of the second electrode layer 31b, and the film thickness of the second film thickness portion is the film thickness of the second electrode layer 31 b. In the common electrode 32 of the present modification, the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer 32a and the film thickness of the second electrode layer 32b, and the film thickness of the second film thickness portion is the film thickness of the second electrode layer 32 b.

(other embodiments)

As described above, the discussion and drawings that form a part of the disclosure are illustrative of one embodiment and should not be construed as limiting. Various alternative implementations, embodiments, and application techniques will be apparent to those skilled in the art in light of this disclosure. As described above, this embodiment includes various embodiments and the like not described herein.

< thermal Printer >

The thermal head (e.g., thermal head 100) further includes a substrate 15 (not shown in fig. 14, such as a heat storage layer 33 on the substrate 15), a connection substrate 5, a heat sink 8, a drive IC7, a plurality of wires 81, a resin portion 82, and a connector 59. The board 15 and the connection board 5 are mounted on the heat sink 8 adjacently in the sub-scanning direction Y. A plurality of heating resistor portions 41 aligned in the main scanning direction X are formed on the substrate 15. The heat generating resistor 41 is driven to selectively generate heat by the drive IC7 mounted on the connection board 5. The heat-generating resistor 41 prints on a print medium 92 such as thermal paper pressed by the platen roller 91 against the heat-generating resistor 41, based on a print signal transmitted from the outside via the connector 59.

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

The heat sink 8 has a function of radiating heat from the substrate 15. The heat sink 8 is mounted with a board 15 and a connection board 5. For example, a metal such as aluminum may be used as the heat dissipation member 8.

For example, a conductor such as gold is used for the wire 81. The wiring 81 has a plurality of parts, and a part thereof is connected to the driver IC7 and each individual electrode by bonding. In addition, some of the other wires 81 are connected to the driver IC7 and the connector 59 by bonding through the wiring layer in the connection substrate 5.

For example, black resin can be used for the resin portion 82. As the resin portion 82, for example, epoxy resin, silicone resin, or the like can be used. The resin portion 82 covers the drive IC7 and the plurality of wires 81 and the like, and protects the drive IC7 and the plurality of wires 81. The connector 59 is fixed to the connection substrate 5. The connector 59 is connected with wiring for supplying power to the thermal head from outside the thermal head and for controlling the drive IC 7.

The thermal printer can have the thermal print head described above. The thermal printer performs printing on a printing medium conveyed along the sub-scanning direction Y. Typically, the printing medium is transported from the connector 59 side to the heat generating resistor portion 41 side. Examples of the printing medium include thermal paper used for producing barcode paper and receipts.

The thermal printer includes, for example, a thermal head 100, a platen roller 91, a main power circuit, a circuit for measurement, and a control unit. The platen roller 91 is opposed to the thermal head 100.

The main power supply circuit supplies power to the plurality of heating resistor sections 41 in the thermal head 100. The measuring circuit measures the resistance value of each of the plurality of heating resistor units 41. The measuring circuit measures the resistance value of each of the plurality of heating resistor units 41 when printing on the printing medium is not performed, for example. This can confirm the life of the heat generating resistor 41 or the presence or absence of the failure of the heat generating resistor 41.

The control unit controls the driving states of the main power supply circuit and the measurement circuit. The control unit controls the energization state of each of the plurality of heating resistor units 41. The measurement circuit may be omitted.

The connector 59 is used to communicate with devices external to the thermal printhead 100. The thermal head 100 is electrically connected to a main power supply circuit and a measurement circuit via a connector 59. The thermal head 100 is electrically connected to the control section via a 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 heating resistor units 41 based on the signal received from the control unit. Specifically, the driver IC7 selectively energizes the plurality of individual electrodes to arbitrarily generate heat in any one of the plurality of heat generation resistor sections 41.

The thermal head is not limited to the above-described configuration, and for example, the drive IC7 may be directly mounted on the substrate 15 without providing the connection substrate 5, flip-chip mounting may be performed without providing the wire 81, or the heat sink 8 may be provided.

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

When printing on a print medium is to be performed, a first potential is applied as an input signal from the main power supply circuit to the connector 59. In this case, the plurality of heating resistor portions 41 are selectively energized and generate heat. By transferring this heat to the print medium, printing onto the print medium is completed. As described above, when the first potential is applied to the connector 59 from the main power supply circuit, the current-carrying paths to the respective plural heat generating resistor sections 41 can be ensured.

When printing on the printing medium is not performed, the resistance value of each heating resistor 41 is measured. When the resistance value of the heating resistor 41 is measured, no potential is applied to the connector 59 from the main power supply circuit. When the resistance value of each heating resistor 41 is measured, a second potential is applied from the measurement circuit to the connector 59. In this case, the plurality of heating resistor portions 41 are energized sequentially (for example, sequentially from the heating resistor portions 41 located at the end portions in the main scanning direction X). The measurement circuit measures the resistance value of each heating resistor 41 based on the value of the current flowing through the heating resistor 41 and the second potential. As described above, when the second potential is applied from the main power supply circuit to the connector 59, the current-carrying paths to the respective plural heat generating resistor sections 41 are substantially blocked. Thus, the resistance value of each heating resistor 41 can be measured more accurately by the measuring circuit, and the life of the heating resistor 41 and the presence or absence of the occurrence of the failure of the heating resistor 41 can be confirmed.

According to the above, a thermal printer ensuring good printing efficiency can be obtained.

Claims

1. A thermal printhead, comprising:

a heat storage layer;

a heating resistor disposed on the heat storage layer;

a common electrode disposed on the heat storage layer and having a comb-tooth portion; and

an individual electrode disposed on the heat storage layer, spaced apart from the comb-teeth portion of the common electrode and opposed to the comb-teeth portion,

the individual electrode and the comb teeth each have a first film thickness portion and a second film thickness portion smaller than the first film thickness portion in a thickness direction of the heat storage layer,

the heating resistor is in contact with the second film thickness portion of the individual electrode and the second film thickness portion of the comb-tooth portion.

2. The thermal printhead of claim 1, wherein:

the heating resistor is disposed on the individual electrode and the comb teeth at a contact portion between the heating resistor and the individual electrode and the comb teeth.

3. The thermal printhead of claim 1, wherein:

the individual electrodes and the common electrode are disposed on the heating resistor at contact portions of the heating resistor with the individual electrodes and the comb teeth.

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

the common electrode further has a common portion connected to the comb-tooth portion,

the common portion has the same film thickness as the first film thickness portion.

5. The thermal printhead of any one of claims 1 to 4, wherein:

the material of the individual electrodes and the material of the common electrode contain silver or gold.

6. The thermal printhead of any one of claims 1 to 5, wherein:

the heat storage layer is arranged on the upper surface of the substrate,

the substrate is composed of ceramic.

7. A thermal printer, characterized by:

a thermal printhead having any one of claims 1 to 6.

8. A method of manufacturing a thermal printhead, comprising:

a heat storage layer is formed and a heat storage layer is formed,

on the heat storage layer, a common electrode and an individual electrode are formed so as to have a first film thickness portion and a second film thickness portion, respectively, wherein the common electrode has a comb-tooth portion, the individual electrode is spaced apart from and opposed to the comb-tooth portion,

forming heating resistors on the comb teeth portions and on the individual electrodes,

The thickness of the second film thickness portion is smaller than that of the first film thickness portion in the thickness direction of the heat storage layer,

9. The method of manufacturing a thermal printhead of claim 8, wherein:

the forming of the individual electrodes and the common electrode includes:

forming a first electrode layer on the heat storage layer; and

a step of forming a second electrode layer on the first electrode layer except for a region overlapping with the heat generating resistor in the thickness direction of the heat storage layer,

the film thickness of the first film thickness portion is the sum of the film thickness of the first electrode layer and the film thickness of the second electrode layer,

the film thickness of the second film thickness portion is the film thickness of the first electrode layer.

10. The method of manufacturing a thermal printhead of claim 8, wherein:

the forming of the individual electrodes and the common electrode includes:

forming a first electrode layer on the heat storage layer except for a region overlapping with the heating resistor in a thickness direction of the heat storage layer; and

a step of forming a second electrode layer on the first electrode layer and on the heat storage layer in a region overlapping with the heat generating resistor,

the second film thickness portion is a film thickness of the second electrode layer.

11. A method of manufacturing a thermal printhead, comprising:

a heat storage layer is formed and a heat storage layer is formed,

a heating resistor is formed on the heat storage layer,

forming a common electrode and an individual electrode on the heat storage layer and the heating resistor body so as to have a first film thickness portion and a second film thickness portion, respectively, wherein the common electrode has a comb-tooth portion, the individual electrode is spaced apart from and opposed to the comb-tooth portion,

12. The method of manufacturing a thermal printhead of claim 11, wherein:

the forming of the individual electrodes and the common electrode includes:

A step of forming a second electrode layer on the first electrode layer and on the heating resistor,

the film thickness of the second film thickness portion is the film thickness of the second electrode layer.

13. The method of manufacturing a thermal printhead of claim 11, wherein:

the forming of the individual electrodes and the common electrode includes:

forming a first electrode layer on the heat storage layer and on the heating resistor; and