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

Abstract

To provide a thermal print head securing excellent printing properties; to provide a manufacturing method for the thermal print head; and to provide a thermal printer equipped with the thermal print head.SOLUTION: A thermal print head 100 includes: a heat accumulation layer 33; a heating resistor 40 arranged on the heat accumulation layer 33; a common electrode 32 arranged on the heat accumulation layer 33 and having a plurality of comb teeth 32A; a plurality of individual electrodes 31 arranged in a main scanning direction X of the thermal print head 100 by turns with the respective comb teeth; and electric conductors 30 arranged separately between the respective comb teeth 32A and the individual electrodes 31. A part of the respective comb teeth 32A, a part of the respective individual electrodes 31, and a part of the respective electric conductors 30 are collectively arranged between the heat accumulation layer 33 and the heating resistor 40 or on the heating resistor 40.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present embodiment relates to a thermal print head, a thermal printer, and a method for manufacturing a thermal print head.

Background Art

[0002] A thermal print head includes, for example, a large number of heat generating portions arranged in the main scanning direction of the thermal print head on a head substrate. 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 the head substrate. By passing an electric current between the common electrode and the individual electrode, the heat generating portion of the resistor layer generates heat due to Joule heat. By transferring the heat to a printing medium (such as a barcode sheet or thermal paper for creating a receipt), printing on the printing medium is performed.

[0003] The common electrode and the individual electrode, etc., are formed into an electrode pattern by sputtering or screen printing a paste using a metal such as gold or silver (a lithography process may be further performed).

[0004] In recent years, traceability has been emphasized, and all kinds of information such as a manufacturer-specific symbol, a manufacturing date, and an expiration date are described on printing media such as labels and receipts. Further, in food products, etc., the obligation to display nutritional components and the change of allergy display, etc., the amount of printed information and the label printing amount in the logistics field are on an increasing trend.

[0005] In order to enable a large amount of printing that is on an increasing trend, it is necessary for the thermal print head to print information on the printing medium at high speed and with high definition. In order to print at high speed and with high definition, it is important to evenly disperse the distribution of heat generated by energization.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, when a resistor layer having a long length in the sub-scanning direction is used for a thermal print head, when an electric current is passed between a common electrode and an individual electrode, unevenness occurs in the distribution of heat around the resistor layer in the sub-scanning direction.

[0008] One aspect of the present embodiment aims to provide a thermal print head ensuring good printing characteristics. Another aspect aims to provide a method for manufacturing the thermal print head. Still another aspect aims to provide a thermal printer including the thermal print head.

MEANS FOR SOLVING THE PROBLEMS

[0009] One aspect of the present embodiment includes a heat storage layer, a first heating resistor disposed on the heat storage layer, a common electrode disposed on the heat storage layer and having a plurality of comb teeth portions, a plurality of individual electrodes alternately arranged with each comb tooth portion in the main scanning direction of the thermal print head, and a conductor disposed separately between each comb tooth portion and each individual electrode, and a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are collectively disposed either between the heat storage layer and the first heating resistor or on the first heating resistor, which is a thermal print head.

[0010] Another aspect of the present embodiment is a thermal printer including the above thermal print head.

[0011] In addition, another aspect of the present embodiment includes a heat storage layer forming step of forming a heat storage layer on a substrate, a heating resistor forming step of forming a first heating resistor on the heat storage layer, and before or after the heating resistor forming step, on the heat storage layer, a common electrode having a plurality of comb teeth, and a plurality of individual electrodes arranged alternately with each comb tooth in the main scanning direction of the thermal print head, and a conductor disposed separately between each comb tooth and each individual electrode, and an electrode forming step of simultaneously forming them, and a part of each comb tooth, a part of each individual electrode, and a part of each conductor are integrally disposed either between the heat storage layer and the first heating resistor or on the first heating resistor. It is a method for manufacturing a thermal print head.

Advantages of the Invention

[0012] According to the present embodiment, it is possible to provide a thermal print head that ensures good printing characteristics. In addition, it is possible to provide a method for manufacturing the thermal print head. Further, it is possible to provide a thermal printer equipped with the thermal print head.

Brief Description of the Drawings

[0013]

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[0014] 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, it should be noted that the drawings are schematic, and the relationships such as the thickness and planar dimensions of each component are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. Of course, there are also portions where the relationships and ratios of the dimensions to each other are different among the drawings.

[0015] In addition, the embodiments described below exemplify devices and methods for embodying technical ideas, and do not specify the materials, shapes, structures, arrangements, etc. of each component. Various modifications can be made to this embodiment within the scope of the claims.

[0016] One aspect of the specific embodiment is as follows.

[0017] <1> A thermal print head comprising a heat storage layer, a first heating resistor disposed on the heat storage layer, a common electrode disposed on the heat storage layer and having a plurality of comb teeth portions, a plurality of individual electrodes alternately arranged with each comb tooth portion in the main scanning direction of the thermal print head, and a conductor disposed separately between each comb tooth portion and each individual electrode, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are collectively disposed either between the heat storage layer and the first heating resistor or on the first heating resistor.

[0018] <2> The thermal print head according to <1>, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are disposed between the heat storage layer and the first heating resistor.

[0019] <3> The thermal print head according to <1>, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are disposed on the first heating resistor.

[0020] According to <1> to <3>, since a current path is formed in which current flows from the comb tooth portion of the common electrode to the individual electrode through the conductor, in the heat generation region of the heating resistor (heating resistance portion), it is possible to evenly disperse the heat distribution in the main scanning direction and the sub-scanning direction of the thermal print head. Therefore, good printing characteristics can be ensured.

[0021] <4> Further provided with a second heating resistor which is disposed on the heat storage layer and is separated from the first heating resistor in the sub-scanning direction of the thermal print head, and a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are collectively disposed either between the heat storage layer and the first heating resistor and the second heating resistor or on either the first heating resistor or the second heating resistor. The thermal print head according to <1>.

[0022] <5> A part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are disposed between the heat storage layer and the first heating resistor and the second heating resistor. The thermal print head according to <4>.

[0023] <6> A part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are disposed on the first heating resistor and the second heating resistor. The thermal print head according to <4>.

[0024] <4> to <6>, since a current path is formed in which current flows from the comb tooth portion of the common electrode to the individual electrode through the conductor, in the heat generation region of the heating resistor (heating resistance portion), it is possible to evenly disperse the heat distribution in the main scanning direction and the sub-scanning direction of the thermal print head. For this reason, good printing characteristics can be ensured. Further, by providing a second heating resistor in addition to the first heating resistor, the heat distribution in the above heat generation region can be made more uniform, so the peak temperature of the heating resistor (heating resistance portion) is reduced. By reducing the peak temperature, local concentration of heat is suppressed, and physical destruction of the heating resistor is suppressed, so good energy withstand voltage can be ensured. Further, by reducing the peak temperature of the heating resistor (heating resistance portion), sticking (adhesion to thermal paper, etc.) can be suppressed.

[0025] <7> Further having a substrate on which the heat storage layer is disposed on the upper surface, and the substrate is made of ceramic. The thermal print head according to any one of <1> to <6>.

[0026] According to <7>, a substrate with excellent heat dissipation properties can be used for the thermal print head.

[0027] <8> A thermal printer comprising the thermal print head according to any one of <1> to <7>.

[0028] According to <8>, a thermal printer with good printing characteristics can be obtained.

[0029] <9> A method for manufacturing a thermal print head, comprising: a heat storage layer forming step of forming a heat storage layer on a substrate; a heating resistor forming step of forming a first heating resistor on the heat storage layer; and an electrode forming step of simultaneously forming, before or after the heating resistor forming step, a common electrode having a plurality of comb teeth on the heat storage layer, a plurality of individual electrodes arranged alternately with each comb tooth in the main scanning direction of the thermal print head, and a conductor arranged separately between each comb tooth and each individual electrode, wherein a part of each comb tooth, a part of each individual electrode, and a part of each conductor are collectively arranged either between the heat storage layer and the first heating resistor or on the first heating resistor.

[0030] <10> The heating resistor forming step includes a step of simultaneously forming a second heating resistor spaced apart from the first heating resistor in the sub-scanning direction of the thermal print head, and a part of each comb tooth, a part of each individual electrode, and a part of each conductor are collectively arranged either between the heat storage layer and the first heating resistor and the second heating resistor or on the first heating resistor and the second heating resistor. The method for manufacturing a thermal print head according to <9>.

[0031] <11> The electrode forming step is performed before the heating resistor forming step. The method for manufacturing a thermal print head according to <9> or <10>.

[0032] <12> The electrode forming step is performed after the heating resistor forming step. The method for manufacturing a thermal print head according to <9> or <10>.

[0033] According to <9>, <11>, and <12>, since the conductor, the individual electrode, and the common electrode are formed on the same surface (on the heat storage layer or on the first heating resistor) in the same process, without increasing the manufacturing process, in the heat generation region around the heating resistor (heating resistor portion), it is possible to evenly disperse the heat distribution in the main scanning direction and the sub-scanning direction of the thermal print head. Therefore, good printing characteristics can be ensured.

[0034] According to <10> to <12>, by providing a second heating resistor in addition to the first heating resistor, the heat distribution in the above heat generation region can be made more uniform, so the peak temperature of the heating resistor (heating resistor portion) is reduced. By reducing the peak temperature, local concentration of heat is suppressed, and physical destruction of the heating resistor is suppressed, so good energy withstand voltage can be ensured. Also, by reducing the peak temperature of the heating resistor (heating resistor portion), sticking (adhesion to thermal paper, etc.) can be suppressed. Furthermore, since the conductor, the individual electrode, and the common electrode are formed on the same surface (on the heat storage layer, or on the first heating resistor and the second heating resistor) in the same process, without increasing the manufacturing process, in the heat generation region around the heating resistor (heating resistor portion), it is possible to evenly disperse the heat distribution in the main scanning direction and the sub-scanning direction of the thermal print head. Therefore, good printing characteristics can be ensured.

[0035] <Thermal Print Head> The thermal print head 100 according to this embodiment will be described with reference to the drawings.

[0036] FIG. 1A is a partial perspective view showing a thermal print 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 taken along line IC-IC of FIG. 1A. FIGS. 1A to 1C show a part (corresponding to one thermal print head) of a thermal printer including a plurality of thermal print heads. In the present embodiment, this one thermal print head is an individual-piece thermal print head 100. The thermal print head 100 includes a substrate 15 which is an insulator, a heat storage layer 33 on the substrate 15, a common electrode 32 disposed on the heat storage layer 33 and having a plurality of comb teeth portions 32A, a plurality of individual electrodes 31 arranged alternately with the respective comb teeth portions 32A in the main scanning direction X of the thermal print head 100, a conductor 30 disposed spaced apart between each comb tooth portion 32A and each individual electrode 31, a heating resistor 40 disposed on the heat storage layer 33, on a part of each comb tooth portion 32A, on a part of each individual electrode 31, and on a part of each conductor 30, and a protective film 34 covering each conductor 30, each individual electrode 31, the common electrode 32, and the heating resistor 40. A part of each comb tooth portion 32A, a part of each individual electrode 31, and a part of each conductor 30 are collectively disposed between the heat storage layer 33 and the heating resistor 40. A part of the region between each conductor 30 and each individual electrode 31 or each comb tooth portion 32A is embedded by the heating resistor 40. The heating resistor 40 includes a plurality of heating resistor portions 41 that generate heat by an electric current flowing between the individual electrode 31 and the common electrode 32 (comb tooth portion 32A). The plurality of heating resistor portions 41 are independently formed between the individual electrode 31 and the common electrode 32. The plurality of heating resistor portions 41 are linearly arranged on the heat storage layer 33. Also, for easy understanding, FIG. 1A omits the illustration of the protective film 34.

[0037] In the present embodiment, the direction in which the heating resistor 40 extends linearly is defined 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 defined as the sub-scanning direction Y, and the direction corresponding to the thickness of the substrate 15 is defined as the thickness direction Z. In other words, the thickness direction Z is perpendicular to each of the main scanning direction X and the sub-scanning direction Y. Also, the direction in which the heat storage layer 33 is located as viewed from the substrate 15 is defined as the upward direction, and the direction in which the substrate 15 is located as viewed from the heat storage layer 33 is defined as the downward direction.

[0038] The heating resistor 40 is in contact with each individual electrode 31, each comb tooth portion 32A, and a conductor 30 disposed between each individual electrode 31 and each comb tooth portion 32A. A current flows from the comb tooth portion 32A through the heating resistor 40 to the conductor 30, and further, a current flows from the conductor 30 through the heating resistor 40 to the individual electrode 31. In the heating resistor 40, the portion through which the current flows generates heat. Specifically, the heating resistor 40 (heating resistance portion 41) to which a heating voltage is individually applied according to a printing signal transmitted from the outside to a driving IC or the like is selectively heated. The heating resistance portion 41 is selectively heated by being individually energized according to the printing signal. By generating heat in this way, printing dots are formed. By forming a current path in which a current flows from the comb tooth portion 32A through the conductor 30 to the individual electrode 31 as described above, in the heating region around the heating resistor 40 (heating resistance portion 41), the heat distribution can be evenly dispersed not only in the main scanning direction X but also in the sub-scanning direction Y, and the printing characteristics on the printing medium can be improved.

[0039] The heating resistor 40 is made of a material having a higher resistivity than the materials constituting the conductor 30, the individual electrode 31, and the common electrode 32. For example, ruthenium oxide or the like can be used.

[0040] In addition, in this specification and the like, "electrically connected" includes cases where connection is made through "something having some electrical effect". Here, "something having some electrical effect" is not particularly limited as long as it enables the transfer of electrical signals between the connection targets. For example, "something having some electrical effect" includes electrodes, wiring, switching elements, resistance elements, inductors, capacitance elements, and other elements having various functions.

[0041] 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, for example, a silicon substrate or the like can be used. From the viewpoint of heat dissipation, it is preferable to use alumina, which has a relatively high thermal conductivity, for the substrate 15.

[0042] The heat storage layer 33 accumulates heat generated from the heat generating resistance portion 41. The heat storage layer 33 can use an insulating material. For example, silicon oxide, which is the main component of glass, or silicon nitride can be used for the heat storage layer 33. The dimension in the thickness direction Z of the heat storage layer 33 is not particularly limited and is, for example, 5 to 200 μm, preferably 10 to 30 μm.

[0043] On the heat storage layer 33, a conductor 30, an individual electrode 31, and a common electrode 32 having a plurality of comb teeth portions 32A formed from a metal paste are provided. The conductor 30, the individual electrode 31, and the common electrode 32 can be obtained together by applying a metal paste, which is the material of the conductor 30, the material of the individual electrode 31, and the material of the common electrode 32, to the heat storage layer 33 by screen printing or the like and then firing to form an electrode pattern. In addition to screen printing, a lithography process may be performed to form the conductor 30, the individual electrode 31, and the common electrode 32. Alternatively, a film may be formed using a sputtering method and a lithography process may be performed to form the conductor 30, the individual electrode 31, and the common electrode 32.

[0044] Since the conductor 30, the individual electrodes 31, and the common electrode 32 are formed in the same process, the conductor 30, the individual electrodes 31, and the common electrode 32 are formed on the same surface (in this embodiment, on the heat storage layer 33). Since the conductor 30, the individual electrodes 31, and the common electrode 32 can be formed in the same process, without increasing the manufacturing process, in the heat generation region around the heating resistor 40 (heating resistance portion 41), it is possible to evenly disperse the heat distribution not only in the main scanning direction X but also in the sub-scanning direction Y.

[0045] As the metal paste, for example, a paste containing metal particles such as copper, silver, palladium, iridium, platinum, and gold can be used. When using the sputtering method, for example, a target processed from a metal such as copper, silver, palladium, iridium, platinum, gold, and aluminum can be used. Also, an organometallic compound can be used as the metal paste. From the viewpoints of the properties and ionization tendency of the metal, silver and gold are preferred, and from the viewpoints of the properties, ionization tendency, and cost reduction of the metal, silver is more preferred. Further, the solvent contained in the metal paste has a function of uniformly dispersing the metal particles, and examples include, but are not limited to, a mixture of one or more of an ester-based solvent, a ketone-based solvent, a glycol ether-based solvent, an aliphatic-based solvent, an alicyclic-based solvent, an aromatic-based solvent, an alcohol-based solvent, and water.

[0046] Examples of ester solvents include ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, dimethyl carbonate, etc. Examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, diisobutyl ketone, diacetone alcohol, isophorone, cyclohexanone, etc. Examples of glycol ether solvents include ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, etc., acetates of these monoethers, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc., and acetates of these monoethers, etc.

[0047] Examples of aliphatic solvents include n-heptane, n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, etc. Examples of alicyclic solvents include methylcyclohexane, ethylcyclohexane, cyclohexane, etc. Examples of aromatic solvents include toluene, xylene, tetralin, etc. Examples of alcohol solvents (excluding the above-mentioned glycol ether solvents) include ethanol, propanol, butanol, etc.

[0048] The metal paste can contain, as necessary, a dispersant, a surface treatment agent, an anti-friction improver, an infrared absorber, an ultraviolet absorber, a fragrance, an antioxidant, an organic pigment, an inorganic pigment, an antifoaming agent, a silane coupling agent, a titanate coupling agent, a plasticizer, a flame retardant, a moisturizing agent, an ion scavenger, etc.

[0049] Each individual electrode 31 is generally in a strip shape extending in the sub-scanning direction Y, and they are not electrically connected to each other. Therefore, when a printer incorporating a thermal print head is used, different potentials can be individually applied to each individual electrode 31. An individual pad portion (not shown) is connected to the end of each individual electrode 31.

[0050] The common electrode 32 is a portion that has an electrical polarity opposite to that of the plurality of individual electrodes 31 when a printer incorporating the thermal print head is used. The common electrode 32 has a comb tooth portion 32A and a common portion 32B connected to the comb tooth portion 32A. The common portion 32B is formed in the main scanning direction X along the upper edge of the substrate 15. In the sub-scanning direction Y, the direction in which the common portion 32B of the common electrode 32 is located as viewed from the individual electrode 31 is defined as the upper side in the sub-scanning direction Y. Each comb tooth portion 32A has a strip shape extending in the sub-scanning direction Y. Each comb tooth portion 32A and each individual electrode 31 face the conductor 30 with a predetermined interval therebetween along the sub-scanning direction Y. By adopting such a configuration, the pitch of the heat generating resistance portion 41 can be narrowed, enabling high-definition printing.

[0051] The heat generating resistor 40 can be formed by baking a resistor paste. In this embodiment, the dimension of the heat generating resistor 40 in the thickness direction Z is, for example, about 1 to 10 μm.

[0052] The heat generating resistor 40 and the like are covered with a protective film 34, and the protective film 34 protects the heat generating resistor 40 and the like from wear, corrosion, oxidation, etc. 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 a glass paste and then baking it. Alternatively, the protective film 34 may be formed by a sputtering method. The dimension of the protective film 34 in the thickness direction Z is, for example, about 2 to 8 μm. A thickness within this range is preferable because it can suppress breakdown voltage failure and obtain a thermal print head 100 capable of maintaining good printing quality.

[0053] Also, in this embodiment, since the heat generating resistor 40 is provided on the conductor 30, the individual electrode 31, and the common electrode 32, and the heat generating resistor 40 is further covered with the protective film 34, the unevenness of the upper surface of the protective film 34 due to the thickness of each of the conductor 30, the individual electrode 31, and the common electrode 32 can be reduced, and the contact property with the printing medium can be improved.

[0054] Furthermore, when the protective film 34 comes into contact with the printing medium multiple times by printing, the thickness of the protective film 34 becomes thinner due to friction with the printing medium. However, even if the friction part causes the protective film 34 to disappear due to friction with the printing medium, the heating resistor 40 is exposed without the conductor 30, the individual electrode 31, and the common electrode 32 being exposed. Therefore, a short circuit between the conductor 30, the individual electrode 31, and the common electrode 32 and the printing medium can be suppressed.

[0055] Here, a method for manufacturing the thermal print head 100 of the present embodiment will be described.

[0056] As shown in FIGS. 2A to 2C, first, a substrate 15 is prepared, and a heat storage layer 33 is formed on the substrate 15 (this step is also referred to as the heat storage layer forming step).

[0057] The heat storage layer 33 can be formed, for example, by applying a glass paste to the substrate 15 by screen printing or the like, drying the applied glass paste, and then performing a firing process. The firing process is performed, for example, at 800 to 1200 ° C for 10 minutes to 1 hour. The dimension in the thickness direction Z of the heat storage layer 33 is, for example, 25 μm.

[0058] Next, as shown in FIGS. 3A to 3C, the conductor 30, the individual electrode 31, and the common electrode 32 are simultaneously formed on the heat storage layer 33 (this step is also referred to as the electrode forming step). The conductor 30, the individual electrode 31, and the common electrode 32 are obtained by applying the above-described metal paste to the heat storage layer 33 by screen printing or the like, then firing, and performing a lithography process. Alternatively, a film may be formed using a sputtering method, and a lithography process may be performed to form the conductor 30, the individual electrode 31, and the common electrode 32. The dimension in the thickness direction Z of the conductor 30, the individual electrode 31, and the common electrode 32 is, for example, 1 to 5 μm.

[0059] By the above-described process, the conductor 30, the individual electrodes 31, and the common electrode 32 can be formed on the same surface (on the heat storage layer 33) in the same process. Therefore, in the heat generation region around the heating resistor 40 (heating resistance portion 41), the heat distribution can be evenly dispersed not only in the main scanning direction X but also in the sub-scanning direction Y without increasing the manufacturing process. For this reason, good printing characteristics can be ensured.

[0060] Next, as shown in FIGS. 4A to 4C, a resistor paste that becomes the heating resistor 40 (heating resistance portion 41) is formed. The resistor paste contains, for example, ruthenium oxide. Next, by firing the above-described resistor paste, the heating resistor 40 (heating resistance portion 41) is formed (this process is also referred to as the heating resistor forming process).

[0061] Next, as shown in FIGS. 5A to 5C, a protective film 34 is formed. The protective film 34 is made of, for example, amorphous glass. The protective film 34 is formed by thick film printing a glass paste and then firing it. Further, the protective film 34 may be formed by using a sputtering method.

[0062] By the above processes, the thermal print head 100 of the present embodiment can be manufactured.

[0063] According to the present embodiment, by forming a current path through which current flows from the comb teeth portion 32A to the individual electrodes 31 via the conductor 30, in the heat generation region around the heating resistor 40 (heating resistance portion 41), the heat distribution can be evenly dispersed in both the main scanning direction X and the sub-scanning direction Y. Further, since the conductor 30, the individual electrodes 31, and the common electrode 32 can be formed on the same surface (on the heat storage layer 33) in the same process, in the heat generation region around the heating resistor 40 (heating resistance portion 41), the heat distribution can be evenly dispersed in both the main scanning direction X and the sub-scanning direction Y without increasing the manufacturing process. For this reason, good printing characteristics can be ensured.

[0064] Furthermore, according to the present embodiment, unevenness on the upper surface of the protective film 34 due to the thicknesses of the conductor 30, the individual electrodes 31, and the common electrode 32 can be reduced, the contact property with the printing medium can be improved, and a short circuit between the conductor 30, the individual electrodes 31, and the common electrode 32 and the printing medium can be suppressed.

[0065] <First Modification Example> The configuration of the thermal print head 100A according to this modification example will be described.

[0066] FIG. 6A is a partial perspective view showing the thermal print head 100A. 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 line VIC-VIC of FIG. 6A. The thermal print head 100A includes a substrate 15 which is an insulator, a heat storage layer 33 on the substrate 15, a common electrode 32 which is disposed on the heat storage layer 33 and has a plurality of comb teeth portions 32A, a plurality of individual electrodes 31 which are alternately arranged with the respective comb teeth portions 32A in the main scanning direction X of the thermal print head 100A, a conductor 30 which is disposed at a distance between each comb tooth portion 32A and each individual electrode 31, two heating resistors 40 which are disposed on the heat storage layer 33, on a part of each comb tooth portion 32A, on a part of each individual electrode 31, and on a part of each conductor 30, and a protective film 34 which covers each conductor 30, each individual electrode 31, the common electrode 32, and the two heating resistors 40. A part of each comb tooth portion 32A, a part of each individual electrode 31, and a part of each conductor 30 are collectively disposed between the heat storage layer 33 and the two heating resistors 40. A part of the region between each conductor 30 and each individual electrode 31 or each comb tooth portion 32A is filled by the heating resistor 40. In FIG. 6A, the illustration of the protective film 34 is omitted for easy understanding. The difference between the thermal print head 100A according to this modification example and the thermal print head 100 shown in FIGS. 1A to 1C described above is that the two heating resistors 40 are disposed on the heat storage layer 33, on a part of each comb tooth portion 32A, on a part of each individual electrode 31, and on a part of each conductor 30. The points common to the thermal print head 100 shown in FIGS. 1A to 1D in this modification example are applied to the above description, and hereinafter, the different points will be described.

[0067] The two heating resistors 40 are spaced apart from each other in the sub-scanning direction Y of the thermal print head 100A. In the heating resistor forming step described above, two resistor pastes can be formed so as to be spaced apart in the sub-scanning direction Y, and by firing these, two heating resistors 40 spaced apart from each other in the sub-scanning direction Y can be formed. Since the locations where heat is generated are more dispersed due to the heating resistors 40 being arranged spaced apart from each other in the sub-scanning direction Y, the heat distribution around the heating resistors 40 in the sub-scanning direction Y can be made more uniform.

[0068] The interval between the two heating resistors 40 in the sub-scanning direction Y is not particularly limited. Also, if the two heating resistors 40 are spaced apart at equal intervals from the central portion of the conductor 30 in the sub-scanning direction Y, the heat distribution around the heating resistors 40 (heating resistance portions 41) in the sub-scanning direction Y can be made more uniform. Furthermore, in this modified example, the configuration is such that two heating resistors 40 are arranged, but it is not limited to this. For example, a configuration in which three heating resistors 40 are arranged or a configuration in which four or more heating resistors 40 are arranged may also be acceptable.

[0069] According to this modification example, by forming a current path through which current flows from the comb teeth portion 32A to the individual electrodes 31 via the conductor 30, it becomes possible to evenly disperse the heat distribution in the heat generation region around the heating resistor 40 (heating resistor portion 41) in the main scanning direction X and the sub-scanning direction Y. Further, by providing a plurality of heating resistors 40 extending in the main scanning direction X that are arranged at intervals along the sub-scanning direction Y, the above heat distribution can be made more uniform, so that the peak temperature of the heating resistor 40 (heating resistor portion 41) is reduced. By reducing the peak temperature, local concentration of heat is suppressed and physical destruction of the heating resistor 40 is suppressed, so that good energy withstand voltage can be ensured. Furthermore, by reducing the peak temperature of the heating resistor 40 (heating resistor portion 41), sticking (adhesion to thermal paper, etc.) can be suppressed. Further, since the conductor 30, the individual electrodes 31, and the common electrode 32 can be formed on the same surface (on the heat storage layer 33) in the same process, without increasing the manufacturing process, in the heat generation region around the heating resistor 40 (heating resistor portion 41), it becomes possible to evenly disperse the heat distribution in the main scanning direction X and the sub-scanning direction Y. For this reason, good printing characteristics can be ensured.

[0070] <Second Modification Example> The configuration of the thermal print head 100B according to this modification example will be described.

[0071] FIG. 7A is a partial perspective view showing the thermal printhead 100B. 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. The thermal printhead 100B includes a substrate 15 which is an insulator, a heat storage layer 33 on the substrate 15, a common electrode 32 disposed on the heat storage layer 33 and having a plurality of comb teeth portions 32A, a plurality of individual electrodes 31 arranged alternately with each of the comb teeth portions 32A in the main scanning direction X of the thermal printhead 100B, a conductor 30 disposed spaced apart between each of the comb teeth portions 32A and each of the individual electrodes 31, a heating resistor 40 disposed on the heat storage layer 33, on a part of each of the comb teeth portions 32A, on a part of each of the individual electrodes 31, and on a part of each of the conductors 30, and a protective film 34 covering each of the conductors 30, each of the individual electrodes 31, the common electrode 32, and the heating resistor 40. A part of each of the comb teeth portions 32A, a part of each of the individual electrodes 31, and a part of each of the conductors 30 are collectively disposed between the heat storage layer 33 and the heating resistor 40. A part of the region between each of the conductors 30 and each of the individual electrodes 31 or each of the comb teeth portions 32A is embedded by the heating resistor 40. FIG. 7A omits the illustration of the protective film 34 for ease of understanding. The difference between the thermal printhead 100B according to this modification and the thermal printhead 100 shown in FIGS. 1A to 1C described above is the shape of the heating resistor 40. The points common to the thermal printhead 100 shown in FIGS. 1A to 1C in this modification are incorporated by reference in the above description, and the differences will be described below.

[0072] In this modification, in the above-described heating resistor forming step, two resistor pastes are formed so that a part of each overlaps in the sub-scanning direction Y, and by firing these, the cross-section of the heating resistor 40 along the line VIIC-VIIC may have a shape with a depression (specifically, an M-shaped or circular sawtooth-shaped). Even with such formation of the heating resistor 40, since the heat generating portions are more dispersed, the heat distribution around the heating resistor 40 (heating resistance portion 41) in the sub-scanning direction Y can be made more uniform.

[0073] According to this modification example, by forming a current path through which current flows from the comb teeth portion 32A to the individual electrode 31 via the conductor 30, in the heat generation region around the heating resistor 40 (heating resistor portion 41), it is possible to evenly disperse the heat distribution in the main scanning direction X and the sub-scanning direction Y. Further, by making the cross-section of the heating resistor 40 have a shape with a depression, the above heat distribution can be made more uniform, so the peak temperature of the heating resistor 40 (heating resistor portion 41) is reduced. By reducing the peak temperature, local concentration of heat is suppressed, and physical destruction of the heating resistor 40 is suppressed, so good energy withstand voltage can be ensured. Furthermore, by reducing the peak temperature of the heating resistor 40 (heating resistor portion 41), sticking (adhesion to thermal paper, etc.) can be suppressed. Further, since the conductor 30, the individual electrode 31, and the common electrode 32 can be formed on the same surface (on the heat storage layer 33) in the same process, without increasing the manufacturing process, in the heat generation region around the heating resistor 40 (heating resistor portion 41), it is possible to evenly disperse the heat distribution in the main scanning direction X and the sub-scanning direction Y. Therefore, good printing characteristics can be ensured.

[0074] <The third modification example> The configuration of the thermal print head 100C according to this modification example will be described.

[0075] FIG. 8A is a partial perspective view showing a thermal print head 100C. 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. The thermal print head 100C includes a substrate 15 which is an insulator, a heat storage layer 33 on the substrate 15, a heating resistor 40 disposed on the heat storage layer 33, a common electrode 32 disposed on the heat storage layer 33 and on the heating resistor 40 and having a plurality of comb teeth portions 32A, a plurality of individual electrodes 31 alternately arranged with the respective comb teeth portions 32A in the main scanning direction X of the thermal print head 100C, a conductor 30 disposed at intervals between each comb teeth portion 32A and each individual electrode 31, and a protective film 34 covering each conductor 30, each individual electrode 31, the common electrode 32, and the heating resistor 40. A part of each comb teeth portion 32A, a part of each individual electrode 31, and a part of each conductor 30 are collectively disposed on the heating resistor 40. FIG. 8A omits the illustration of the protective film 34 for ease of understanding. The difference between the thermal print head 100C according to this modification and the thermal print head 100 shown in FIGS. 1A to 1C described above is that a part of each comb teeth portion 32A, a part of each individual electrode 31, and a part of each conductor 30 are collectively disposed on the heating resistor 40.

[0076] Here, a method for manufacturing the thermal print head 100C of this modification will be described.

[0077] First, as shown in FIGS. 2A to 2C, the substrate 15 is prepared, and the heat storage layer 33 is formed on the substrate 15. Next, as shown in FIGS. 9A to 9C, a resistor paste that will become the heating resistor 40 (heating resistor portion 41) is formed on the heat storage layer 33. The resistor paste contains, for example, ruthenium oxide. Next, the heating resistor 40 (heating resistor portion 41) is formed by firing the above-described resistor paste (heating resistor forming step).

[0078] Next, as shown in FIGS. 10A to 10C, a conductor 30, individual electrodes 31, and a common electrode 32 are simultaneously formed on the heat storage layer 33 and the heating resistor 40 (electrode forming step). The conductor 30, the individual electrodes 31, and the common electrode 32 are obtained by applying the above-described metal paste to the heat storage layer 33 and the heating resistor 40 by screen printing or the like, followed by baking and performing a lithography process. Alternatively, the conductor 30, the individual electrodes 31, and the common electrode 32 may be formed by film deposition using a sputtering method and performing a lithography process. The dimensions of the conductor 30, the individual electrodes 31, and the common electrode 32 in the thickness direction Z are, for example, 1 to 5 μm.

[0079] By the above process, the conductor 30, the individual electrodes 31, and the common electrode 32 can be formed on the same surface (on the heat storage layer 33 and the heating resistor 40) in the same process. Therefore, in the heat generation region around the heating resistor 40 (heating resistance portion 41), the heat distribution can be evenly dispersed not only in the main scanning direction X but also in the sub-scanning direction Y without increasing the manufacturing process. For this reason, good printing characteristics can be ensured.

[0080] Next, as shown in FIGS. 11A to 11C, a protective film 34 is formed. The protective film 34 is made of, for example, amorphous glass. The protective film 34 is formed by thick film printing a glass paste and then baking it. Alternatively, the protective film 34 may be formed by film deposition using a sputtering method.

[0081] Through the above steps, the thermal print head 100C of this modified example can be manufactured.

[0082] According to this modification example, by forming a current path through which current flows from the comb teeth portion 32A to the individual electrode 31 via the conductor 30, it is possible to evenly disperse the heat distribution in the heat generation region around the heating resistor 40 (heating resistance portion 41) in the main scanning direction X and the sub-scanning direction Y. Further, since the conductor 30, the individual electrode 31, and the common electrode 32 can be formed on the same surface (on the heat storage layer 33) in the same process, it is possible to evenly disperse the heat distribution in the heat generation region around the heating resistor 40 (heating resistance portion 41) in the main scanning direction X and the sub-scanning direction Y without increasing the manufacturing process. Therefore, good printing characteristics can be ensured.

[0083] (Other Embodiments) As described above, although one embodiment has been described, the discussions and drawings forming a part of the disclosure are exemplary and should not be understood as limiting. Various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art from this disclosure. Thus, this embodiment includes various embodiments not described herein.

[0084] For example, in the thermal print head 100C, two heating resistors 40 may be provided as shown in the thermal print head 100A, or the cross-section of the heating resistor 40 may have a shape with a depression as shown in the thermal print head 100B.

[0085] <Thermal Printer> A thermal print head (for example, thermal print head 100) further includes a substrate 15 (the heat storage layer 33 etc. on the substrate 15 are not shown), a connection substrate 5, a heat dissipation member 8, a driving IC 7, a plurality of wires 81, a resin part 82, and a connector 59 as shown in FIG. 12. The substrate 15 and the connection substrate 5 are mounted adjacent to each other in the sub-scanning direction Y on the heat dissipation member 8. A plurality of heat generating resistor parts 41 arranged in the main scanning direction X are formed on the substrate 15. The heat generating resistor parts 41 are driven to selectively generate heat by the driving IC 7 mounted on the connection substrate 5. The heat generating resistor parts 41 perform printing on a printing medium 92 such as thermal paper that is pressed against the heat generating resistor parts 41 by a platen roller 91 according to a printing signal transmitted from the outside via the connector 59.

[0086] The connection substrate 5 can use, for example, a printed wiring board. The connection substrate 5 has a structure 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, metals such as copper, silver, palladium, iridium, platinum, and gold.

[0087] The heat dissipation member 8 has a function of dissipating heat from the substrate 15. The substrate 15 and the connection substrate 5 are attached to the heat dissipation member 8. The heat dissipation member 8 can use, for example, a metal such as aluminum.

[0088] The wires 81 can use, for example, a conductor such as gold. There are a plurality of wires 81, and a part of them is electrically connected between the driving IC 7 and each individual electrode by bonding. Also, a part of the other wires 81 is electrically connected between the driving IC 7 and the connector 59 through the wiring layer in the connection substrate 5 by bonding.

[0089] The resin part 82 can use, for example, a black resin. As the resin part 82, for example, an epoxy resin, a silicone resin, etc. can be used. The resin part 82 covers the drive IC 7 and the plurality of wires 81, etc., and protects the drive IC 7 and the plurality of wires 81. The connector 59 is fixed to the connection substrate 5. Wires for supplying power from outside the thermal print head to the thermal print head and for controlling the drive IC 7 are connected to the connector 59.

[0090] The thermal printer can include the above-described thermal print head. The thermal printer performs printing on a print medium conveyed along the sub-scanning direction Y. Usually, the print medium is conveyed from the connector 59 side toward the heat generating resistance part 41 side. Examples of the print medium include a bar code sheet or thermal paper for creating a receipt.

[0091] The thermal printer includes, for example, a thermal print head 100, a platen roller 91, a main power circuit, a measurement circuit, and a control unit. The platen roller 91 faces the thermal print head 100.

[0092] The main power circuit supplies power to the plurality of heat generating resistance parts 41 in the thermal print head 100. The measurement circuit measures the resistance value of each of the plurality of heat generating resistance parts 41. The measurement circuit measures the resistance value of each of the plurality of heat generating resistance parts 41, for example, when printing is not performed on the print medium. Thereby, the life of the heat generating resistance part 41 and the presence or absence of a failed heat generating resistance part 41 can be confirmed. The control unit controls the driving states of the main power circuit and the measurement circuit. The control unit controls the energization state of each of the plurality of heat generating resistance parts 41. The measurement circuit may be omitted.

[0093] The connector 59 is used for communicating with a device outside the thermal print head 100. Through the connector 59, the thermal print head 100 is electrically connected to the main power circuit and the measurement circuit. Through the connector 59, the thermal print head 100 is electrically connected to the control unit.

[0094] The drive IC 7 receives a signal from the control unit via the connector 59. Based on the signal received from the control unit, the drive IC 7 controls the energization state of each of the plurality of heat-generating resistance portions 41. Specifically, the drive IC 7 selectively energizes a plurality of individual electrodes to arbitrarily generate heat in any one of the plurality of heat-generating resistance portions 41.

[0095] Also, the thermal print head is not limited to the above-described configuration. For example, the drive IC 7 may be directly mounted on the substrate 15 without providing the connection substrate 5, or the wire 81 may not be provided by flip-chip mounting, or the heat dissipation member 8 may not be provided.

[0096] Next, a method of using the thermal printer will be described.

[0097] When printing on a printing medium, a first potential, which is an input signal, is applied to the connector 59 from the main power circuit. In this case, the plurality of heat-generating resistance portions 41 are selectively energized and generate heat. By transferring the heat to the printing medium, printing on the printing medium is performed. As described above, when the first potential is applied to the connector 59 from the main power circuit, an energization path to each of the plurality of heat-generating resistance portions 41 is ensured.

[0098] When not printing on a printing medium, the resistance value of each heating resistor 41 is measured. At the time of such measurement, no potential is applied from the main power supply circuit to the connector 59. When measuring the resistance value of each heating resistor 41, a second potential is applied from a measurement circuit to the connector 59. In this case, a plurality of heating resistors 41 are energized in order (for example, in order from the heating resistor 41 located at the end in the main scanning direction X). Based on the value of the current flowing through the heating resistor 41 and the second potential, the measurement circuit measures the resistance value of each heating resistor 41. As described above, when the second potential is applied from the main power supply circuit to the connector 59, the energization path to each of the plurality of heating resistors 41 is substantially blocked. Thereby, the measurement circuit can more accurately measure the resistance value of each heating resistor 41, and the life of the heating resistor 41 and the presence or absence of a failed heating resistor 41 can be confirmed.

[0099] According to the above, a thermal printer with good printing characteristics can be obtained.

Explanation of Signs

[0100] 5 Connection substrate 7 Driving IC 8 Heat dissipation member 15 Substrate 30 Conductor 31 Individual electrode 32 Common electrode 32A Comb teeth part 32B Common part 33 Heat storage layer 34 Protective film 40 Heating resistor 41 Heating resistor part 59 Connector 81 Wire 82 Resin part 91 Platen roller 92 Printing medium 100, 100A, 100B, 100C Thermal print head

Claims

1. A heat storage layer, a first heating resistor disposed on the heat storage layer, a common electrode disposed on the heat storage layer, the common electrode having a plurality of comb teeth portions, a plurality of individual electrodes alternately arranged with each comb tooth portion in the main scanning direction of the thermal print head, and a conductor disposed spaced apart between each comb tooth portion and each individual electrode, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are collectively disposed either between the heat storage layer and the first heating resistor or on the first heating resistor, a thermal print head.

2. A thermal print head according to claim 1, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are disposed between the heat storage layer and the first heating resistor.

3. A thermal print head according to claim 1, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are disposed on the first heating resistor.

4. further comprising a second heating resistor disposed on the heat storage layer and spaced apart from the first heating resistor in the sub-scanning direction of the thermal print head, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are collectively disposed either between the heat storage layer and the first heating resistor and the second heating resistor or on the first heating resistor and the second heating resistor, a thermal print head according to claim 1.

5. A thermal print head according to claim 4, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are disposed between the heat storage layer and the first heating resistor and the second heating resistor.

6. A thermal print head according to claim 4, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are disposed on the first heating resistor and the second heating resistor.

7. further comprising a substrate on which the heat storage layer is disposed on the upper surface, wherein the substrate is made of ceramic, a thermal print head according to any one of claims 1 to 6.

8. A thermal printer comprising the thermal print head according to any one of claims 1 to 7.

9. a heat storage layer forming step of forming a heat storage layer on a substrate, a heating resistor forming step of forming a first heating resistor on the heat storage layer, Before or after the heat-generating resistor forming step, on the heat storage layer, a common electrode having a plurality of comb teeth portions, a plurality of individual electrodes alternately arranged with each comb tooth portion in the main scanning direction of the thermal print head, and a conductor disposed separately between each comb tooth portion and each individual electrode are simultaneously formed, and an electrode forming step. A method of manufacturing a thermal print head, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are collectively disposed either between the heat storage layer and the first heat-generating resistor or on the first heat-generating resistor.

10. The heat-generating resistor forming step includes a step of simultaneously forming a second heat-generating resistor spaced apart from the first heat-generating resistor in the sub-scanning direction of the thermal print head. A method of manufacturing a thermal print head according to claim 9, wherein a part of each comb tooth portion, a part of each individual electrode, and a part of each conductor are collectively disposed either between the heat storage layer and the first heat-generating resistor and the second heat-generating resistor or on the first heat-generating resistor and the second heat-generating resistor.

11. The method of manufacturing a thermal print head according to claim 9 or 10, wherein the electrode forming step is performed before the heat-generating resistor forming step.

12. The method of manufacturing a thermal print head according to claim 9 or 10, wherein the electrode forming step is performed after the heat-generating resistor forming step.

Images