Thermal printhead, method of manufacturing the same, and thermal printer

Abstract

The present invention provides a thermal head having good thermal responsiveness, a manufacturing method of the thermal head, and a thermal printer having the thermal head. The thermal head has an insulator, a heat radiating layer on the insulator, a heat accumulating layer on the insulator and the heat radiating layer, and a heat generating resistor on the heat accumulating layer, the heat radiating layer containing a material different from that of the heat accumulating layer, at least a part of the heat radiating layer and the heat generating resistor overlapping each other as viewed in a thickness direction of the heat radiating layer.

Description

TECHNICAL FIELD

[0001] The present embodiment relates to a thermal printhead and a manufacturing method thereof, and a thermal printer. BACKGROUND

[0002] A thermal printhead has, for example, a plurality of heat generating portions arranged in a main scanning direction on a main substrate. Each heat generating portion is formed by allowing a part of a heat generating resistor to be exposed on a resistor layer formed on the main substrate with a glaze layer interposed therebetween, and stacking a common electrode and an individual electrode so that their end portions face each other. By applying electric current between the common electrode and the individual electrode, the exposed portion of the resistor layer (heat generating portion) generates heat due to Joule heat. By transferring the heat to a print medium (thermal paper or the like used for making bar code paper or a receipt), printing on the print medium is completed.

[0003] In recent years, traceability is valued, and all information such as factory-specific marks, production dates, shelf lives, and the like is recorded on print media such as labels and receipts, and for food, there is a trend toward an increase in the amount of print information and the amount of label printing in the logistics field, and the like, due to the mandatory display of nutritional ingredients or changes in the display of allergic reactions.

[0004] In order to be able to implement a large amount of printing that is in a trend toward an increase, a thermal printhead is required to print information on a print medium at high speed and with high resolution. In order to print at high speed and with high resolution, good thermal responsiveness of the thermal printhead is required.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT DOCUMENTS

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-141729 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] One embodiment of the present embodiment provides a thermal printhead having good thermal responsiveness. In addition, another embodiment of the present embodiment provides a manufacturing method of the thermal printhead. Further, still another embodiment of the present embodiment provides a thermal printer having the thermal printhead.

[0010] TECHNICAL MEANS FOR SOLVING THE PROBLEMS

[0011] The present embodiment, by having at least a part of the heat dissipation layers overlapping each other with the heat generating resistors, heat dissipation from the heat dissipation layer having a smaller thermal resistance becomes active, and a thermal printhead having good thermal responsiveness can be obtained. One embodiment of the present embodiment is as described below.

[0012] One embodiment of the present application is a thermal head including: a heat radiating layer over an insulator; a heat accumulating layer over the insulator and the heat radiating layer; and a heat generating resistor over the heat accumulating layer, the heat radiating layer including a material different from that of the heat accumulating layer, at least a portion of the heat radiating layer and the heat generating resistor overlapping each other in a thickness direction of the heat radiating layer.

[0013] Another embodiment of the present application is a thermal printer including the above thermal head.

[0014] Another embodiment of the present application is a manufacturing method of a thermal head, in which an insulator is formed, a heat radiating layer is formed over the insulator, a heat accumulating layer is formed over the insulator and the heat radiating layer, and a heat generating resistor is formed over the heat accumulating layer, the heat radiating layer including a material different from that of the heat accumulating layer, at least a portion of the heat radiating layer and the heat generating resistor overlapping each other in a thickness direction of the heat radiating layer.

[0015] Effects of Invention

[0016] According to the present application, a thermal head having good thermal responsiveness can be provided. In addition, a manufacturing method of the thermal head can be provided. Further, a thermal printer including the thermal head can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a partial perspective view of a thermal head according to the present application.

[0018] Figure 2 FIG. 2 is a partial cross-sectional view of the thermal head of FIG. 1 along A-A line thereof in a main scanning direction X. Figure 1

[0019] Figure 3 FIG. 3 is a partial cross-sectional view of the thermal head of FIG. 1 along B-B line thereof in a sub scanning direction Y. Figure 1

[0020] Figure 4 FIG. 4 is a partial perspective view of a manufacturing method of the thermal head according to the present application (one).

[0021] Figure 5 FIG. 5 is a partial cross-sectional view of the thermal head of FIG. 4 along A-A line thereof in the main scanning direction X. Figure 4

[0022] Figure 6 FIG. 6 is a partial cross-sectional view of the thermal head of FIG. 4 along B-B line thereof in the sub scanning direction Y. Figure 4

[0023] Figure 7 FIG. 7 is a partial perspective view of the manufacturing method of the thermal head according to the present application (two). ​​​​

[0024] Figure 8 is a partial cross-sectional view of the A-A line of the thermal head 1 along the main scanning direction X. Figure 7

[0025] Figure 9 is a partial cross-sectional view of the B-B line of the thermal head 1 along the sub-scanning direction Y. Figure 7

[0026] Figure 10 is a partial perspective view (No. 3) that explains the manufacturing method of the thermal head of the present embodiment.

[0027] Figure 11 is a partial cross-sectional view of the A-A line of the thermal head 1 along the main scanning direction X. Figure 10

[0028] Figure 12 is a partial cross-sectional view of the B-B line of the thermal head 1 along the sub-scanning direction Y. Figure 10

[0029] Figure 13 is a partial perspective view (No. 4) that explains the manufacturing method of the thermal head of the present embodiment.

[0030] Figure 14 is a partial cross-sectional view of the A-A line of the thermal head 1 along the main scanning direction X. Figure 13

[0031] Figure 15 is a partial cross-sectional view of the B-B line of the thermal head 1 along the sub-scanning direction Y. Figure 13

[0032] Figure 16 is a partial perspective view (No. 5) that explains the manufacturing method of the thermal head of the present embodiment.

[0033] Figure 17 is a partial cross-sectional view of the A-A line of the thermal head 1 along the main scanning direction X. Figure 16

[0034] Figure 18 is a partial cross-sectional view of the B-B line of the thermal head 1 along the sub-scanning direction Y. Figure 16

[0035] Figure 19 is a partial cross-sectional view of the thermal head of the present embodiment along the sub-scanning direction Y.

[0036] Figure 20 is a partial cross-sectional view of the thermal head of the present embodiment along the sub-scanning direction Y.

[0037] Figure 21 is a cross-sectional view that explains the thermal head of the present embodiment. ​​​​​​​​

[0038] Explanation of reference numerals

[0039] 5 connection substrate

[0040] 7 drive IC

[0041] 8 heat dissipation member

[0042] 15 substrate

[0043] 20, 25 insulating film

[0044] 30 heat dissipation layer

[0045] 31 independent electrode

[0046] 32 common electrode

[0047] 32A comb-tooth portion

[0048] 32B common portion

[0049] 33 heat storage layer

[0050] 34 protective film

[0051] 40 heat generating resistor

[0052] 41 heat generating resistor portion

[0053] 59 connector

[0054] 81 lead wire

[0055] 82 resin portion

[0056] 91 platen roller

[0057] 92 print medium

[0058] 100, 100A, 100B thermal printhead DETAILED DESCRIPTION

[0059] Next, the present embodiment will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic representations, and it should be noted that the relationships between the thicknesses and planar dimensions of the respective components, and the like, can differ from the actual relationships. Therefore, the actual thicknesses and dimensions should be determined with reference to the following description. Further, the drawings naturally include parts in which the relationships or proportions differ from one another.

[0060] Further, the embodiments shown below are examples of devices or methods for embodying the technical ideas, and do not specify the materials, shapes, configurations, arrangements, and the like, of the respective components. Various modifications can be added to the present embodiment within the scope of the claims.

[0061] One embodiment of the present application is described below.

[0062] <1> A thermal head comprising: an insulator; a heat radiating layer on the insulator; a heat accumulating layer on the insulator and on the heat radiating layer; and a heat generating resistor on the heat accumulating layer, the heat radiating layer containing a material different from the heat accumulating layer, at least a portion of the heat radiating layer and the heat generating resistor overlapping each other as viewed in a thickness direction of the heat radiating layer.

[0063] <2> The thermal head described in <1>, wherein a thermal resistance of the heat radiating layer is smaller than a thermal resistance of the insulator.

[0064] <3> The thermal head described in <1> or <2>, wherein a thermal resistance of the heat radiating layer is smaller than a thermal resistance of the heat accumulating layer.

[0065] <4> The thermal head described in any one of <1> to <3>, wherein the heat radiating layer is in contact with the insulator.

[0066] <5> The thermal head described in any one of <1> to <4>, wherein the heat radiating layer is in contact with the heat accumulating layer.

[0067] <6> The thermal head described in any one of <1> to <5>, wherein the heat radiating layer is in an electrically floating state.

[0068] <7> The thermal head described in any one of <1> to <6>, wherein the heat radiating layer is a metal containing at least any one element selected from the group consisting of gold, silver, copper, aluminum, and platinum, or an insulator.

[0069] <8> The thermal head described in any one of <1> to <7>, wherein the insulator is a substrate.

[0070] <9> The thermal head described in <8>, wherein the substrate is formed of a ceramic.

[0071] <10> The thermal head described in any one of <1> to <9>, wherein an average surface roughness of a surface of the insulator is greater than 0 μm and is 10 μm or less.

[0072] <11> The thermal head described in any one of <1> to <10>, further comprising: an individual electrode on the heat accumulating layer and electrically connected to the heat generating resistor; and a common electrode on the heat accumulating layer, electrically connected to the heat generating resistor, spaced apart from the individual electrode, and opposed to the individual electrode.

[0073] <12> A thermal printer having the thermal head described in any one of <1> to <11>.

[0074] <13> A method of manufacturing a thermal printhead, a heat dissipation layer is formed on an insulator, a heat storage layer is formed on the insulator and the heat dissipation layer, and a heat generating resistor is formed on the heat storage layer, the heat dissipation layer contains a different material from the heat storage layer, and at least a part of the heat dissipation layer and the heat generating resistor overlap each other as viewed in a thickness direction of the heat dissipation layer.

[0075] <14> The method of manufacturing a thermal printhead described in <13>, wherein a thermal resistance of the heat dissipation layer is smaller than a thermal resistance of the insulator.

[0076] <15> The method of manufacturing a thermal printhead described in <13> or <14>, wherein a thermal resistance of the heat dissipation layer is smaller than a thermal resistance of the heat storage layer.

[0077] <16> The method of manufacturing a thermal printhead described in any one of <13> to <15>, wherein the heat dissipation layer is in contact with the insulator.

[0078] <17> The method of manufacturing a thermal printhead described in any one of <13> to <16>, wherein the heat dissipation layer is in contact with the heat storage layer.

[0079] <18> The method of manufacturing a thermal printhead described in any one of <13> to <17>, wherein the insulator is a substrate.

[0080] <19> The method of manufacturing a thermal printhead described in <18>, wherein the substrate is composed of ceramic.

[0081] <20> The method of manufacturing a thermal printhead described in any one of <13> to <19>, wherein an average surface roughness of the insulator is greater than 0 μm and is 10 μm or less.

[0082] <Thermal printhead>

[0083] A thermal printhead according to the present embodiment will be described with reference to the drawings.

[0084] Figure 1 is a partial perspective view of a thermal printhead. Figure 2 is a partial cross-sectional view of the thermal printhead along the A-A line of Figure 1 . Figure 3 is a partial cross-sectional view of the thermal printhead along the B-B line of Figure 1 . Figures 1-3A portion of a thermal head (corresponding to 1 thermal head) is shown, and in the present embodiment, the 1 thermal head is provided as a single-piece thermal head 100. The thermal head 100 includes a substrate 15 that is an insulator, a heat dissipation layer 30 on the substrate 15, a heat storage layer 33 on the substrate 15 and the heat dissipation layer 30, independent electrodes 31 on the heat storage layer 33, common electrodes 32 on the heat storage layer 33 that are spaced apart from the independent electrodes 31 and face the independent electrodes 31, heat generating resistors 40 on the heat storage layer 33, the independent electrodes 31, and the common electrodes 32, and a protective film 34 that covers the independent electrodes 31, the common electrodes 32, and the heat generating resistors 40. At least a portion of the heat dissipation layer 30 and the heat generating resistors 40 overlap each other when viewed in a thickness direction of the heat dissipation layer 30 described later. In addition, the heat generating resistors 40 include a plurality of heat generating resistor portions 41 that generate heat by a current flowing between the independent electrodes 31 and the common electrodes 32. Regarding the plurality of heat generating resistor portions 41, each heat generating resistor portion 41 is formed independently between the independent electrodes 31 and the common electrodes 32. Figure 1 The plurality of heat generating resistor portions 41 are omitted in FIG. 1. The plurality of heat generating resistor portions 41 are arranged in a linear shape on the heat storage layer 33. In addition, Figure 1 The protective film 34 is omitted for easy understanding.

[0085] In the present embodiment, a direction in which the plurality of heat generating resistor portions 41 extend in a linear shape is taken as a main scanning direction X, a direction that is perpendicular to the main scanning direction X and parallel to an upper surface of the substrate 15 is taken as a sub-scanning direction Y, and a direction corresponding to a thickness of the substrate 15 is taken as a thickness direction Z. In other words, the thickness direction Z is a direction that is perpendicular to each of the main scanning direction X and the sub-scanning direction Y.

[0086] The substrate 15 is an insulator, for example, formed of ceramic. As the ceramic, for example, alumina or the like can be applied. From the viewpoint of heat dissipation, it is preferable to use alumina having a relatively large thermal conductivity for the substrate 15. In addition, as described later, in order to obtain a uniform distribution of thermal responsiveness, it is preferable to make the average surface roughness of the substrate 15 that is an insulator small, and the average surface roughness of the substrate 15 is preferably greater than 0 μm and 10 μm or less, and more preferably greater than 0 μm and 1 μm or less, for example. Furthermore, the average surface roughness can be obtained in accordance with JIS B 0601:2013 or ISO 25178, for example.

[0087] On the substrate 15 formed of alumina or the like, a heat dissipation layer 30 formed of a low thermal resistance material is layered. The heat dissipation layer 30 preferably has heat resistance against the temperature of a heat treatment or the like at the time of firing of the heat storage layer 33, the individual electrode 31, and the common electrode 32, or the like to be formed later. The heat dissipation layer 30 is preferably formed using, for example, a metal paste containing at least one element selected from among gold, silver, copper, aluminum, and platinum, more preferably a metal paste containing silver, and further preferably a metal paste formed of silver. In addition, the heat dissipation layer 30 can also be an insulator. The thermal resistance of the heat dissipation layer 30 is preferably smaller than the thermal resistance of the heat storage layer 33 described later. In addition, it is preferable to be smaller than the thermal resistance of the substrate 15. By providing the heat dissipation layer 30 having small thermal resistance, heat dissipation from the heat dissipation layer 30 becomes active, and good thermal responsiveness can be obtained. The thermal resistance of the heat dissipation layer 30 is, for example, preferably 1 x 10 -6 ~ 1 m 2 K / W.

[0088] In addition, the heat dissipation layer 30 can be in a state connected to a power source, can be in a state grounded, or can be in an electrically floating state. When the heat dissipation layer 30 is in an electrically floating state, there is no possibility of occurrence of power-on heating or the like that would hinder the heat dissipation characteristics, and good thermal responsiveness can be maintained, and thus this is preferable.

[0089] When the heat dissipation layer 30 is formed using a metal paste in contact with the surface of the substrate 15, in the case where there is unevenness on the surface of the substrate 15, the metal paste having high fluidity enters the fine portions of the unevenness of the substrate 15, good adhesion can be obtained, and the fluidity of the metal paste is high, and thus the average surface roughness of the surface of the heat dissipation layer 30 formed by firing the metal paste is smaller than the average surface roughness of the surface of the substrate 15.

[0090] When the average surface roughness of the surface formed by the heat storage layer 33 described later is large, the thickness of the heat storage layer 33 becomes uneven, and uniform distribution of thermal responsiveness cannot be obtained. In the present embodiment, the heat dissipation layer 30 is provided not only to make heat dissipation active, but also to make the average surface roughness of the surface of the heat dissipation layer 30 small, and thus unevenness in the thickness of the heat storage layer 33 formed on the heat dissipation layer 30 can be suppressed, and uniform distribution of thermal responsiveness can be obtained.

[0091] On the substrate 15 and the heat dissipation layer 30, a heat storage layer 33 (also referred to as a glaze layer) having a function of storing heat is layered. The heat storage layer 33 stores heat generated from the heat generating resistance portion 41 described later. From the viewpoint of thermal responsiveness, it is preferable that the heat storage layer 33 be in contact with the heat dissipation layer 30. The heat storage layer 33 can use an insulating material, and for example, can use silicon oxide, silicon nitride as 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, 5 to 100 μm, and is preferably 10 to 30 μm.

[0092] The independent electrodes 31 and the common electrode 32 are provided on the heat storage layer 33. The independent electrodes 31 and the common electrode 32 are obtained by applying a metal paste by a screen printing method or the like, followed by firing, and forming an electrode pattern.

[0093] 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 from the viewpoint of the characteristics, ionization tendency, and cost reduction of the metal, copper and silver are preferable. In addition, the solvent contained in the metal paste has a function of uniformly dispersing the metal particles, and for example, a solvent obtained by mixing one or two or more of ester-based solvents, ketone-based solvents, glycol ether-based solvents, aliphatic-based solvents, alicyclic-based solvents, aromatic-based solvents, alcohol-based solvents, water, or the like can be exemplified, but is not limited thereto.

[0094] The ester-based solvents can be exemplified by ethyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, dimethyl carbonate, or the like. The ketone-based solvents can be exemplified by acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, diisobutyl ketone, diacetone alcohol, isophorone, cyclohexanone, or the like. The glycol ether-based solvents can be exemplified by ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, or 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 acetic acid esters of these monoethers.

[0095] The aliphatic-based solvents can be exemplified by n-heptane, n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, or the like. The alicyclic-based solvents can be exemplified by methylcyclohexane, ethylcyclohexane, cyclohexane, or the like. The aromatic-based solvents can be exemplified by toluene, xylene, tetralin, or the like. The alcohol-based solvents (in addition to the above-described glycol ether-based solvents) can be exemplified by ethanol, propanol, butanol, or the like.

[0096] The metal paste can contain, as necessary, a dispersant, a surface treatment agent, a friction resistance improving agent, an infrared absorbing agent, an ultraviolet absorbing agent, a fragrance, an oxidation inhibitor, an organic pigment, an inorganic pigment, an antifoaming agent, a silane coupling agent, a titanate coupling agent, a plasticizer, a flame retardant, a moisturizer, an ion scavenger, or the like.

[0097] Each independent electrode 31 is formed in a strip shape extending substantially in the sub-scanning direction Y, and they are not conductive to each other. Therefore, for each independent electrode 31, an electric potential different from each other can be independently applied at the time of use of a printer in which the thermal printhead is assembled. An independent pad portion not shown is connected to the end portion of each independent electrode 31.

[0098] The common electrode 32 is a portion that becomes an opposite polarity electrode to the plurality of individual electrodes 31 at the time of use of a printer in which the thermal printhead is assembled. The common electrode 32 has comb teeth portions 32A and a common portion 32B that commonly connects the comb teeth portions 32A. The common portion 32B is formed in the main scanning direction X along the edge of the upper side of the substrate 15. Further, from the individual electrode 31, the direction in which the common electrode 32 is present is the upper side in the sub scanning direction Y. Each comb teeth portion 32A is formed in a band shape extending in the sub scanning direction Y. The leading end portion of each comb teeth portion 32A is positioned in a region between the leading end portions of two adjacent individual electrodes 31, and is opposed to the two individual electrodes 31 at a prescribed interval along the main scanning direction X.

[0099] The leading end portion of each comb teeth portion 32A can also be opposed to the leading end portion of each individual electrode 31 at a prescribed interval along the sub scanning direction Y. In this case, it is preferable that the heat generating resistance portion 41 be formed only in a region in which the leading end portion of the comb teeth portion 32A opposes the leading end portion of the individual electrode 31. In other words, in the main scanning direction X, it is preferable that the heat generating resistance portion 41 not be disposed in a region other than the region in which the leading end portion of the comb teeth portion 32A opposes the leading end portion of the individual electrode 31.

[0100] The heat generating resistance body 40 is electrically connected to the individual electrode 31 and the common electrode 32, and a portion through which current from the individual electrode 31 and the common electrode 32 flows generates heat. Specifically, the heat generating resistance body 40 selectively generates heat in accordance with a heat generating voltage that is independently applied in accordance with a print signal transmitted from the outside to the drive IC or the like. The heat generating resistance portion 41 selectively generates heat by being independently energized in accordance with the print signal. In this way, a print dot is formed by heat generation. The heat generating resistance body 40 can be adapted to a material having a higher resistivity than the material that constitutes the wiring, and, for example, can use ruthenium oxide or the like. The heat generating resistance body 40 can be formed by firing a resistance body paste supplied using a screen printer or a dispenser. In the present embodiment, the dimension of the heat generating resistance body 40 in the thickness direction Z is, for example, on the order of 1 to 10 μm.

[0101] Further, at least a portion of the heat releasing layer 30 and the heat generating resistance body 40 (heat generating resistance portion 41) overlap each other, the path through which heat generated by the heat generating resistance portion 41 is released is shortened, and heat is efficiently released via the heat accumulating layer 33 and the heat releasing layer 30. Further, in the present embodiment, it is not limited that the entire heat generating resistance body 40 and the heat releasing layer 30 overlap each other, and, for example, it can be configured so that the entire heat releasing layer 30 and the heat generating resistance body 40 overlap each other, or it can be configured so that only the end portion of the heat releasing layer 30 overlaps the heat generating resistance body 40.

[0102] The heat storage layer 33, independent electrode 31, common electrode 32, and heating resistor 40 are covered by a protective film 34, protecting them from wear, corrosion, oxidation, etc. The protective film 34 can be made of an insulating material, such as amorphous glass. The protective film 34 is formed by printing a thick film of glass paste and then firing it. The dimension of the protective film 34 in the thickness direction Z is, for example, 3 to 8 μm.

[0103] Here, the manufacturing method of the thermal printhead 100 of this embodiment will be described.

[0104] like Figures 4-6 As shown, a substrate 15 is first prepared, and a heat dissipation layer 30 is formed on the substrate 15. The heat dissipation layer 30 can be formed, for example, by applying metal paste using screen printing or the like, drying the applied metal paste, and then performing a firing process. The firing process is, for example, performed at 800 to 1200°C for 10 minutes to 1 hour.

[0105] The heat dissipation layer 30 preferably has heat resistance relative to the temperature of heat treatments such as firing processes during the formation of the heat storage layer 33, the independent electrode 31, and the common electrode 32, which will be formed later. In addition, since the heat dissipation layer 30 has low thermal resistance, it has the function of improving the heat dissipation of the thermal printhead.

[0106] Next, as Figures 7-9 As shown, a heat storage layer 33 is formed on the substrate 15 and the heat dissipation layer 30. The heat storage layer 33 can be formed by, for example, applying glass paste using screen printing, drying the applied glass paste, and then firing it. The firing process is, for example, carried out at 800 to 1200°C for 10 minutes to 1 hour.

[0107] The heat from the heat storage layer 33 is dissipated through the heat dissipation layer 30, which has low thermal resistance. In addition, since the average surface roughness of the heat dissipation layer 30 is low, unevenness in the thickness of the heat storage layer 33 can be suppressed, and uniform thermal response can be obtained.

[0108] Next, as Figures 10-12 As shown, an independent electrode 31 and a common electrode 32 are formed on the heat storage layer 33. The independent electrode 31 and the common electrode 32 can be obtained by applying the above-mentioned metal paste using screen printing or the like, and then firing it to form an electrode pattern.

[0109] Next, as Figures 13-15As shown, a heating resistor 40 (heating resistor section 41) is formed on multiple individual electrodes 31 and a common electrode 32 using a thick film forming technique. The heating resistor 40 is electrically connected to the multiple individual electrodes 31 and the common electrode 32. The heating resistor 40 is formed by firing a resistor paste supplied by a screen printing machine or a dispenser. The resistor paste may contain, for example, ruthenium oxide.

[0110] Next, as Figures 16-18 The protective film 34 is shown to be formed. The protective film 34 is, for example, made of amorphous glass. The protective film 34 is formed by printing a thick film of glass paste and then firing it.

[0111] The thermal printhead of this embodiment can be manufactured through the above processes.

[0112] According to this embodiment, by providing a heat dissipation layer 30 with low thermal resistance, the heat of the heat storage layer 33 can be dissipated efficiently, resulting in good thermal responsiveness. Furthermore, according to this embodiment, since the average surface roughness of the heat dissipation layer 30 is low, unevenness in the thickness of the heat storage layer 33 can be suppressed, and a uniformly distributed thermal responsiveness can be obtained.

[0113] (Other implementation methods)

[0114] As described above, one embodiment has been described, but the discussions and drawings that form part of the disclosure are illustrative and should not be construed as limiting. Based on this disclosure, those skilled in the art will understand various alternative embodiments, examples, and application techniques. Thus, this embodiment includes various embodiments not described herein.

[0115] For example, thermal printhead 100A, a modified example 1 of the thermal printhead 100 of this embodiment, such as Figure 19 The structure shown comprises an insulating film 20 serving as an insulator disposed between the substrate 15 and the heat dissipation layer 30. Because the average surface roughness of the insulating film 20 is relatively low, unevenness in the thickness of the heat storage layer 33 formed above the insulating film 20 can be suppressed, which is therefore preferable. To reduce the average surface roughness of the insulating film 20, planarization treatment can be performed, for example, using CMP (Chemical Mechanical Polishing). The insulating film 20 can be, for example, silicon oxide or silicon nitride. Even if the average surface roughness of the substrate 15 is relatively high, by providing the insulating film 20 with a low average surface roughness, unevenness in the thickness of the heat storage layer 33 can be suppressed, resulting in a more uniform thermal response.

[0116] Furthermore, as a variation of the thermal printhead 100 in this embodiment, the thermal printhead 100B, such as Figure 20As shown, the structure in which the insulating film 25 is provided between the heat dissipation layer 30 and the heat storage layer 33 can also be configured. Since the average surface roughness of the surface of the insulating film 25 is small, the unevenness of the thickness of the heat storage layer 33 formed on the insulating film 25 can be suppressed, and thus is preferable. The insulating film 25 can be formed, for example, at the atomic level using an ALD (Atomic layer deposition) method or the like capable of forming a very dense film, and thus the average surface roughness of the surface can be made small. The insulating film 25 can use, for example, aluminum oxide, zirconium oxide, or hafnium oxide. Even if the average surface roughness of the surface of the substrate 15 is large, by providing the insulating film 25 having a small average surface roughness, the unevenness of the thickness of the heat storage layer 33 can be suppressed, and a more uniform heat response can be obtained.

[0117] In addition, although not shown, the structure in which the above-described insulating film 20 is provided in the thermal head 100B can also be configured.

[0118] <Thermal printer>

[0119] The thermal head (for example, the thermal head 100) of the present embodiment is further configured as shown Figure 21 The substrate 15 and the connection substrate 5 are mounted on the heat dissipation member 8 so as to be adjacent in the sub-scanning direction Y. A plurality of heat generating resistance portions 41 arranged in the main scanning direction X are formed in the substrate 15. The heat generating resistance portions 41 are driven in a manner to selectively generate heat by the driving IC 7 mounted on the connection substrate 5. The heat generating resistance portions 41 perform printing on a print medium 92 such as a thermal paper pressed by the heat generating resistance portions 41 by a platen roller 91 in accordance with a print signal transmitted from the outside via the connector 59.

[0120] The connection substrate 5 can use, for example, a printed wiring substrate. The connection substrate 5 has a configuration in which a base material layer and a wiring layer not shown are laminated. The base material layer can use, for example, a glass epoxy resin or the like. The wiring layer can use, for example, a metal such as copper, silver, palladium, iridium, platinum, and gold.

[0121] The heat dissipation member 8 has a function of dissipating 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 use, for example, a metal such as aluminum.

[0122] The lead wire 81 can use, for example, a conductor such as gold. The lead wire 81 is a plurality of lead wires, and a part of the lead wire 81 electrically connects the driving IC 7 and each individual electrode by soldering. In addition, a part of the other lead wires 81 electrically connects the driving IC 7 and the connector 59 via the wiring layer in the connection substrate 5 by soldering.

[0123] The resin portion 82 can use, 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 driving IC 7 and the plurality of conductive wires 81 and the like, and protects the driving IC 7 and the plurality of conductive wires 81. The connector 59 is fixed to the connection substrate 5. The connector 59 connects a wiring for supplying electric power from the outside of the thermal head to the thermal head and controlling the driving IC 7.

[0124] The thermal head of the present embodiment can have the thermal head described above. The thermal head is used in a thermal printer. The thermal printer performs printing on a print medium conveyed along a sub-scanning direction Y. Generally, the print medium is conveyed from the side of the connector 59 to the side of the heat generating resistor portion 41. As the print medium, for example, thermal paper used for making bar code paper or receipts and the like can be exemplified.

[0125] The thermal printer has, for example, the thermal head 100, a platen roller 91, a main power supply circuit, a measurement circuit, and a control portion. The platen roller 91 faces the thermal head 100.

[0126] The main power supply circuit supplies electric power to the plurality of heat generating resistor portions 41 in the thermal head 100. The measurement circuit measures the resistance value of each of the plurality of heat generating resistor portions 41. The measurement circuit measures the resistance value of each of the plurality of heat generating resistor portions 41, for example, when printing on the print medium is not performed. Thus, it is possible to confirm the life of the heat generating resistor portions 41 or the presence or absence of a heat generating resistor portion 41 that has failed. The control portion controls the driving state of the main power supply circuit and the measurement circuit. The control portion controls the energization state of each of the plurality of heat generating resistor portions 41. The measurement circuit can be omitted at times.

[0127] The connector 59 is used for communication with a device outside the thermal head 100. The thermal head 100 is electrically connected to the main power supply circuit and the measurement circuit via the connector 59. The thermal head 100 is electrically connected to the control portion via the connector 59.

[0128] The driving IC 7 receives a signal from the control portion via the connector 59. The driving IC 7 controls the energization state of each of the plurality of heat generating resistor portions 41 based on the signal received from the control portion. Specifically, the driving IC 7 selectively energizes the plurality of independent electrodes, and causes any of the plurality of heat generating resistor portions 41 to generate heat arbitrarily.

[0129] In addition, the thermal head of the present embodiment is not limited to the structure described above, and can be configured, for example, not to provide the connection substrate 5 and to mount the driving IC 7 directly on the substrate 15, can be configured not to provide the conductive wires 81 by flip chip mounting, or can be configured not to provide the heat dissipation member 8.

[0130] Next, a method of using the thermal printer will be described.

[0131] When printing is performed on the print medium, the potential v11 as the potential VI is applied from the main power supply circuit to the connector 59. In this case, the plurality of heat generating resistance portions 41 are selectively energized to generate heat. The heat is transferred to the print medium, thereby completing the printing on the print medium. As described above, in the case where the potential v11 as the potential VI is applied from the main power supply circuit to the connector 59, the respective energization paths to the plurality of heat generating resistance portions 41 are ensured.

[0132] When printing is performed on the print medium, the potential v11 as the potential VI is applied from the main power supply circuit to the connector 59. In this case, the plurality of heat generating resistance portions 41 are selectively energized to generate heat. The heat is transferred to the print medium, thereby completing the printing on the print medium. As described above, in the case where the potential v11 as the potential VI is applied from the main power supply circuit to the connector 59, the respective energization paths to the plurality of heat generating resistance portions 41 are ensured.

[0133] According to the present embodiment, a thermal printer having a good thermal responsiveness can be obtained.

[0134] The present application is associated with the subject matter of Japanese Patent Application No. 2020-201847 filed on December 4, 2020, and the entire disclosure thereof is incorporated herein by reference.

Claims

1. A thermal printhead, characterized by, comprises: an insulator; a heat radiating layer on the insulator; a heat accumulating layer on the insulator and on the heat radiating layer; and a heat generating resistor on the heat accumulating layer, the heat radiating layer contains a material different from that of the heat accumulating layer, at least a part of the heat radiating layer and the heat generating resistor overlap each other as viewed in a thickness direction of the heat radiating layer, in a film thickness between a surface of the insulator on a side on which the heat radiating layer and the heat accumulating layer are provided and a surface of the heat accumulating layer on a side on which the heat generating resistor is provided, the film thickness of a portion of the heat radiating layer on which the heat accumulating layer is provided is equal to the film thickness of a portion of the insulator on which the heat accumulating layer is provided.

2. The thermal head according to claim 1, wherein: a thermal resistance of the heat radiating layer is smaller than a thermal resistance of the insulator.

3. The thermal head according to claim 1 or 2, wherein: a thermal resistance of the heat radiating layer is smaller than a thermal resistance of the heat accumulating layer.

4. The thermal head according to any one of claims 1 to 3, wherein: the heat radiating layer is in contact with the insulator.

5. The thermal head according to any one of claims 1 to 4, wherein: the heat radiating layer is in contact with the heat accumulating layer.

6. The thermal head according to any one of claims 1 to 5, wherein: the heat radiating layer is in an electrically floating state.

7. The thermal head according to any one of claims 1 to 6, wherein: the heat radiating layer is a metal containing at least any one of elements selected from the group consisting of gold, silver, copper, aluminum, and platinum, or an insulator.

8. The thermal head according to any one of claims 1 to 7, wherein: the insulator is a substrate.

9. The thermal head according to claim 8, wherein: the substrate is formed of ceramic.

10. The thermal head according to any one of claims 1 to 9, wherein: an average surface roughness of the insulator is greater than 0 μm and is equal to or less than 10 μm. further comprising:

11. The thermal printhead according to any one of claims 1 to 10, wherein an individual electrode on the heat accumulating layer and electrically connected to the heat generating resistor; and a common electrode on the heat accumulating layer, electrically connected to the heat generating resistor, and spaced apart from and opposite to the individual electrode.

12. A thermal printer, comprising: the thermal head according to any one of claims 1 to 11.

13. A method of manufacturing a thermal head, comprising: forming a heat radiating layer on an insulator, forming a heat accumulating layer on the insulator and on the heat radiating layer, forming a heat generating resistor on the heat accumulating layer, the heat radiating layer contains a material different from that of the heat accumulating layer, at least a part of the heat radiating layer and the heat generating resistor overlap each other as viewed in a thickness direction of the heat radiating layer, in a film thickness between a surface of the insulator on a side on which the heat radiating layer and the heat accumulating layer are provided and a surface of the heat accumulating layer on a side on which the heat generating resistor is provided, the film thickness of a portion of the heat radiating layer on which the heat accumulating layer is provided is equal to the film thickness of a portion of the insulator on which the heat accumulating layer is provided. ​ ​ 14. The method of manufacturing a thermal printhead according to claim 13, wherein: the thermal resistance of the heat-dissipating layer is smaller than the thermal resistance of the insulator.

15. The method of manufacturing a thermal printhead according to claim 13 or 14, wherein: the thermal resistance of the heat-dissipating layer is smaller than the thermal resistance of the heat-accumulating layer.

16. The method of manufacturing a thermal printhead according to any one of claims 13 to 15, wherein: the insulator is a substrate.

17. The method of manufacturing a thermal printhead according to claim 16, wherein: the substrate is formed of ceramic.

18. The method of manufacturing a thermal printhead according to any one of claims 13 to 17, wherein: the average surface roughness of the insulator is greater than 0 μm and is 10 μm or less.

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