JP2018062152A - Thermal print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal print head suitable for improving printing properties, such as an increase in printing speed.SOLUTION: A thermal print head has a substrate 1, a glazed layer 2 formed on the substrate 1, an electrode layer 3 formed on the glazed layer 2, and a resistive element layer 4 having a plurality of heat generating parts 41 arranged in main scanning direction. The substrate 1 is an aluminum nitride substrate mainly composed of aluminum nitride, and the glazed layer 2 has a crystallized glass layer 21 in contact with the substrate 1.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a thermal print head.

  Conventionally, a thermal print head is known (for example, see Patent Document 1). The thermal print head disclosed in this document includes a substrate, a glaze layer, an electrode layer, and a resistor layer. The substrate is a plate-like member made of an insulating material, for example, an alumina substrate. The glaze layer 92 is formed on the surface of the substrate 91 and is made of, for example, glass. The electrode layer is formed on the glaze layer 92 and constitutes a current path for allowing a current to flow selectively through the resistor layer 94. The resistor layer has a plurality of heat generating portions arranged in the main scanning direction.

  The thermal print head constitutes the main part of the printer. At the time of printing by the printer, a current is selectively applied to any one of the plurality of heat generating portions, heat from the heat generating portion is transmitted to a print medium such as thermal paper, and dots are printed on the print medium. The print medium is pressed against the plurality of heat generating portions by a platen roller disposed opposite to the plurality of heat generating portions. The print medium is fed in the sub-scanning direction by the rotation of the platen roller. The printing specifications of the printer are various, and improvement of printing characteristics such as energy saving and high printing speed is achieved. In a thermal print head, a heat radiating member is generally provided on the back surface of the substrate, and heat generated during printing is quickly released from the heat radiating member through the substrate. For example, if only the character is printed on the thermal paper, the energized state does not continue in each heat generating portion, and the substrate is not overheated. On the other hand, when the printing mode on the thermal paper is a pattern, a pattern, or the like, the substrate is overheated due to the energized state in each heat generating portion, and printing at high speed is difficult.

Japanese Patent Laid-Open No. 10-16268

  The present invention has been conceived under the circumstances described above, and it is a main object of the present invention to provide a thermal print head suitable for improving printing characteristics such as an increase in printing speed.

  The thermal print head provided by the present invention includes a substrate, a glaze layer formed on the substrate, an electrode layer formed on the glaze layer, and a plurality of heat generating portions arranged in the main scanning direction. A resistor layer, wherein the substrate is an aluminum nitride substrate containing aluminum nitride as a main component, and the glaze layer includes a crystallized glass layer in contact with the substrate.

  Preferably, the glaze layer includes an amorphous glass layer that is located farthest from the substrate and on which the electrode layer is directly formed.

  Preferably, the glaze layer includes a semi-crystallized glass layer interposed between the crystallized glass layer and the amorphous glass layer.

  Preferably, the thickness of the amorphous glass layer is equal to or greater than the thickness of the crystallized glass layer.

  Preferably, the thickness of the amorphous glass layer is 1.5 times or more the thickness of the crystallized glass layer.

  Preferably, the thickness of the crystallized glass layer is equal to or greater than the thickness of the semi-crystallized glass layer.

  Preferably, the glaze layer has a thickness of 60 to 120 μm.

  Preferably, the amorphous glass layer is white or transparent.

  Preferably, at least a part of the substrate has a light-impermeable portion that does not transmit light.

  Preferably, the light-impermeable portion is made of an aluminum nitride composition containing aluminum nitride and a light-impermeable material that does not transmit light.

  Preferably, the light opaque material is carbon.

  Preferably, the light-impermeable portion is formed of a coating film that is formed on the substrate and contains a light-impermeable material that does not transmit light.

  Preferably, the electrode layer includes a common electrode having a connecting portion extending in the main scanning direction and a plurality of common electrode strips extending from the connecting portion in the sub scanning direction, each extending in the sub scanning direction, and the main scanning. A plurality of individual electrodes each having individual electrode strips positioned between the common electrode strips adjacent in the direction.

  Preferably, the resistor layer intersects the plurality of common electrode strips and the plurality of individual electrode strips.

  Preferably, the plurality of common electrode strips and the plurality of individual electrode strips are interposed between the substrate and the resistor layer.

  Preferably, the resistor layer has a strip shape extending long in the main scanning direction.

  Preferably, the resistor layer is a fired body of a resistor paste printed with a thick film.

  Preferably, the glaze layer covers at least a part of one surface in the thickness direction of the substrate.

  Preferably, the glaze layer covers the entire surface of the substrate.

  Preferably, a protective layer covering the resistor layer is provided.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a top view which shows the thermal print head which concerns on embodiment of this invention. It is sectional drawing which follows the II-II line | wire of FIG. FIG. 2 is a partially enlarged plan view (partially omitted) of the thermal print head shown in FIG. 1. FIG. 4 is a partially enlarged sectional view taken along line IV-IV in FIG. 3. FIG. 2 is a partially enlarged sectional view of the thermal print head shown in FIG. 1. FIG. 2 is a partial enlarged cross-sectional view showing one process of manufacturing the thermal print head shown in FIG. 1. FIG. 7 is a partial enlarged cross-sectional view showing a step following FIG. 6. FIG. 8 is a partial enlarged cross-sectional view illustrating a process following FIG. 7. FIG. 9 is a partial enlarged cross-sectional view illustrating a process following FIG. 8. FIG. 10 is a partial enlarged cross-sectional view showing a step following FIG. 9.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  1 to 5 show an example of a thermal print head according to the present invention. The thermal print head A1 of this embodiment includes a substrate 1, a glaze layer 2, an electrode layer 3, a resistor layer 4, a protective layer 5, a drive IC 71, a sealing resin 72, a connector 73, a wiring substrate 74, and a heat dissipation member 75. ing. The thermal print head A1 is incorporated in a printer that performs printing on thermal paper in order to create, for example, a barcode sheet or a receipt. For convenience of understanding, the protective layer 5 is omitted in FIGS. 1 and 3. In these figures, the main scanning direction is the x direction, the sub scanning direction is the y direction, and the thickness direction of the substrate 1 is the z direction.

  FIG. 1 is a plan view showing the thermal print head A1. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is a partially enlarged plan view showing the thermal print head A1. 4 is a partially enlarged sectional view taken along line IV-IV in FIG. FIG. 5 is a partial enlarged cross-sectional view showing the thermal print head A1.

The substrate 1 is an aluminum nitride substrate whose main component is aluminum nitride (AlN), and has a thickness of about 0.6 to 1.0 mm, for example. Regarding the thermal properties of aluminum nitride (AlN), the thermal conductivity is about 80 to 180 W / (m · K), and the thermal expansion coefficient is about 40 to 45 × 10 ⁻⁷ / ° C. As shown in FIG. 1, the substrate 1 has a long rectangular shape that extends long in the main scanning direction x. In the present embodiment, the substrate 1 is an aluminum nitride composition formed by sintering a substrate material containing, for example, aluminum nitride, a light-opaque material that does not transmit light, and other resin binders. Examples of the light-impermeable material include carbon. If an example of the content rate of the composition in the board | substrate 1 is given, aluminum nitride will be 80-95 wt%, and carbon will be 5-20 wt%.

  As shown in FIGS. 1 and 2, in addition to the substrate 1, for example, a structure having a wiring substrate 74 in which a base material layer made of glass epoxy resin and a wiring layer made of Cu or the like are laminated may be used. A heat radiating member 75 made of a metal such as Al is provided on the lower surface of the substrate 1. In the configuration having the wiring substrate 74, for example, the substrate 1 and the wiring substrate 74 are disposed adjacent to each other on the heat dissipation member 75, and the wiring between the electrode layer 3 on the substrate 1 and the wiring substrate 74 (or an IC connected to this wiring) For example, by wire bonding. Further, a connector 73 may be provided on the wiring board 74.

  The glaze layer 2 is formed on the substrate 1 and is made of a glass material. As shown in FIG. 5, in this embodiment, the glaze layer 2 has a laminated structure in which a crystallized glass layer 21, a semi-crystallized glass layer 22, and an amorphous glass layer 23 are laminated in this order.

The crystallized glass layer 21 is in contact with the substrate 1 and is, for example, white. The crystallized glass layer 21 is made of crystallized glass such as SiO ₂ —BaO—Al ₂ O ₃ —ZnO glass, and is formed by printing and baking the crystallized glass paste. The semi-crystallized glass layer 22 is interposed between the crystallized glass layer 21 and the amorphous glass layer 23 and is, for example, white. The semi-crystallized glass layer 22 is made of, for example, semi-crystallized glass such as SiO ₂ —B ₂ O ₃ —BaO—ZnO—Al ₂ O ₃ -based glass, and the paste of the semi-crystallized glass is printed and fired. It is formed. The amorphous glass layer 23 is a portion that is located farthest from the substrate 1 and on which an electrode layer 3 described later is directly formed, and is, for example, white or transparent. The amorphous glass layer 23 is made of amorphous glass such as SiO ₂ —ZnO—MgO glass, and is formed by printing and baking a paste of the amorphous glass. In the present embodiment, the entire upper surface of the substrate 1 in the drawing is covered with the glaze layer 2.

  Illustrating the thickness dimension of each layer of the glaze layer 2, the thickness of the crystallized glass layer 21 is 15 to 30 μm, the thickness of the semi-crystallized glass layer 22 is 15 to 25 μm, and the amorphous glass layer 23 The thickness is 30 to 65 μm. Further, the thickness of the amorphous glass layer 23 is not less than the thickness of the crystallized glass layer 21, and preferably not less than 1.5 times the thickness of the crystallized glass layer 21. The thickness of the crystallized glass layer 21 is preferably equal to or greater than the thickness of the semi-crystallized glass layer 22. The thickness of the entire glaze layer 2 is 60 to 120 μm, preferably 80 to 100 μm. In addition, about the thermal expansion coefficient of each layer of the glaze layer 2, it has become the amorphous glass layer 23, the semi-crystallized glass layer 22, and the crystallized glass layer 21 in the order large.

  The electrode layer 3 is for constituting a path for energizing the resistor layer 4 and is made of a conductor mainly composed of Ag. The electrode layer 3 is not particularly limited as long as it is formed of a conductive material. As one configuration example of the electrode layer 3, a configuration including a first layer 31 and a second layer 32 can be given as illustrated in FIG. 5.

  The first layer 31 is formed on the glaze layer 2 and is formed, for example, by printing and baking a paste containing an organic Ag compound. The first layer 31 contains an organic Ag compound as Ag as a main component. The first layer 31 contains Pd whose content is, for example, greater than 0.1 wt% and less than or equal to 30 wt%. The first layer 31 does not contain glass. The thickness of the first layer 31 is, for example, 0.3 to 1.0 μm.

  The second layer 32 is provided on the first layer 31, and is formed, for example, by printing and baking an Ag paste for thick film printing. The second layer 32 contains Ag powder as the main component Ag. This Ag powder is spherical or flaky and has an average particle size of, for example, 0.1 to 10 μm. Moreover, the 2nd layer 32 contains 0.5-10 wt% glass, for example. This glass is, for example, borosilicate glass or lead borosilicate glass. Further, the second layer 32 includes, for example, Pd that is 0.1 wt% or more and less than 30 wt% and whose content is smaller than that of the first layer 31. The thickness of the second layer 32 is, for example, 2 to 10 μm. The surface of the second layer 32 has a relatively rough property due to the distribution of the Ag powder.

  As shown in FIG. 3, the electrode layer 3 includes a common electrode 33 and a plurality of individual electrodes 36.

  The common electrode 33 has a plurality of common electrode strip portions 34 and a connecting portion 35. The connecting portion 35 is disposed near the downstream end in the sub-scanning direction y of the substrate 1 and has a strip shape extending in the main scanning direction x. Each of the plurality of common electrode strips 34 extends in the sub-scanning direction y from the connecting portion 35 and is arranged at an equal pitch in the main scanning direction x.

  The plurality of individual electrodes 36 are for partially energizing the resistor layer 4, and are portions having a reverse polarity with respect to the common electrode 33. The individual electrode 36 extends from the resistor layer 4 toward the drive IC 71. The plurality of individual electrodes 36 are arranged in the main scanning direction x, and each has an individual electrode strip portion 38, a connecting portion 37, and a bonding portion 39.

  Each individual electrode strip 38 is a strip extending in the sub-scanning direction y, and is positioned between two common electrode strips 34 adjacent to the common electrode 33. The individual electrode strip 38 of the individual electrode 36 and the common electrode strip 34 of the common electrode 33 have a width of, for example, 25 μm or less, and the individual electrode strip 38 of the adjacent individual electrode 36 and the common electrode of the common electrode 33 The distance from the belt-like portion 34 is, for example, 40 μm or less.

  The connecting portion 37 is a portion extending from the individual electrode strip portion 38 toward the drive IC 71, and most of the connecting portion 37 has a portion along the sub-scanning direction y and a portion inclined with respect to the sub-scanning direction y. Most portions of the connecting portion 37 have a width of, for example, 20 μm or less, and an interval between adjacent connecting portions 37 is, for example, 20 μm or less.

  The bonding portion 39 is formed at an end portion in the sub-scanning direction y of the individual electrode 36, and a wire 61 for connecting the individual electrode 36 and the drive IC 71 is bonded thereto. Bonding portions 39 of adjacent individual electrodes 36 are alternately arranged in the sub-scanning direction y. This prevents the bonding portion 39 from interfering with each other even though the bonding portion 39 is wider than most of the portions of the connecting portion 37.

  A portion of the connecting portion 37 sandwiched between adjacent bonding portions 39 has the smallest width in the individual electrode 36, and the width is, for example, 10 μm or less. Further, the distance between the connecting portion 37 and the adjacent bonding portion 39 is, for example, 10 μm or less. Thus, the common electrode 33 and the plurality of individual electrodes 36 have a fine pattern with a small line width and wiring interval.

  The resistor layer 4 is made of, for example, ruthenium oxide having a resistivity higher than that of the material constituting the electrode layer 3, and is formed in a strip shape extending in the main scanning direction x. The resistor layer 4 intersects the plurality of common electrode strips 34 of the common electrode 33 and the individual electrode strips 38 of the plurality of individual electrodes 36. Further, the resistor layer 4 is laminated on the opposite side of the substrate 1 with respect to the plurality of common electrode strips 34 of the common electrode 33 and the individual electrode strips 38 of the plurality of individual electrodes 36. A portion of the resistor layer 4 sandwiched between the common electrode strips 34 and the individual electrode strips 38 is a heat generating portion 41 that generates heat when being partially energized by the electrode layer 3. Print dots are formed by the heat generated by the heat generating portion 41. The thickness of the resistor layer 4 is, for example, 4 μm to 6 μm.

  The protective layer 5 is for protecting the electrode layer 3 and the resistor layer 4. The protective layer 5 is made of amorphous glass, for example. However, the protective layer 5 exposes a region including the bonding portions 39 of the plurality of individual electrodes 36.

  The drive IC 71 fulfills the function of partially heating the resistor layer 4 by selectively energizing the plurality of individual electrodes 36. The driving IC 71 is provided with a plurality of pads. FIG. 5 is an enlarged cross-sectional view of a main part in a yz plane crossing the drive IC 71. As shown in FIGS. 3 and 5, the pad of the driving IC 71 and the plurality of individual electrodes 36 are connected via a plurality of wires 61 bonded to each other. The wire 61 is made of Au. As shown in FIGS. 1 and 5, the driving IC 71 is covered with a sealing resin 72. The sealing resin 72 is made of, for example, a black soft resin. The drive IC 71 and the connector 73 are connected by a signal line (not shown).

  Next, an example of how to use the thermal print head A1 will be briefly described.

  The thermal print head A1 is used in a state incorporated in a printer. As shown in FIG. 2, each heat generating portion 41 of the thermal print head A <b> 1 faces the platen roller 81 in the printer. When the printer is used, the printing medium 82 such as thermal paper is fed at a constant speed between the platen roller 81 and each heat generating portion 41 along the sub-scanning direction y by rotating the platen roller 81. . The print medium 82 is pressed against a portion of the protective layer 5 that covers each heat generating portion 41 by the platen roller 81. On the other hand, a potential is selectively applied to each individual electrode 36 shown in FIG. As a result, a voltage is applied between the common electrode 33 and each of the plurality of individual electrodes 36. Then, current selectively flows through the plurality of heat generating portions 41 to generate heat. The heat generated in each heat generating portion 41 is transmitted to the print medium 82 via the protective layer 5. A plurality of dots are printed in a line region extending linearly in the main scanning direction x on the print medium 82. Further, the heat generated in each heat generating portion 41 is also transmitted to the glaze layer 2 and stored in the glaze layer 2.

  Next, an example of a manufacturing method of the thermal print head A1 will be described below with reference to FIGS.

  First, as shown in FIG. 6, a substrate 1 is prepared. The substrate 1 is an aluminum nitride composition and includes aluminum nitride (AlN) as a main component and carbon (C) as a subcomponent.

  Next, as shown in FIG. 7, the glaze layer 2 is formed on the substrate 1. The glaze layer 2 is formed by laminating the crystallized glass layer 21, the semi-crystallized glass layer 22, and the amorphous glass layer 23 in this order. The crystallized glass layer 21 is formed by firing a thick film of a crystallized glass paste and then firing it. Crystallized glass has a crystallization temperature (for example, 830 to 850 ° C.) higher than a glass softening point (for example, about 780 ° C.) by about 50 to 70 ° C., and is heated to a firing temperature equal to or higher than the crystallization temperature to be crystallized. The surface of the crystallized glass layer 21 formed in this way has fine pores.

  The semi-crystallized glass layer 22 is formed by baking a semi-crystallized glass paste after thick-film printing. The semi-crystallized glass has a crystallization temperature (for example, 790 to 810 ° C.) that is higher by about 50 to 70 ° C. than a glass softening point (for example, about 740 ° C.), and is heated to a firing temperature not lower than the crystallization temperature. Here, the firing temperature of the semi-crystallized glass is lower than the firing temperature of the crystallized glass described above.

  The amorphous glass layer 23 is formed by printing a thick paste of an amorphous glass paste and then firing it. The amorphous glass is heated to a firing temperature that is about 70 to 100 ° C. higher than the glass softening point (for example, about 680 ° C.). Here, the viscosity of the amorphous glass is reduced, the fluidity thereof is sufficiently increased, and the amorphous glass layer 23 having a smooth surface is formed.

  In the glaze layer 2 formed as described above, the crystallized glass layer 21 has fine pores on the surface thereof, and the surface smoothness is inferior to that of the amorphous glass layer 23. In the attached drawings, a mode in which the surface of the crystallized glass layer 21 is relatively rough is conceptually represented as an uneven shape.

  Next, as shown in FIG. 8, the electrode layer 3 is formed. Although the formation method of the electrode layer 3 is not specifically limited, the case where the electrode layer 3 is comprised by the 1st layer 31 and the 2nd layer 32 which were mentioned above is demonstrated coldly. First, a first material layer is formed. The first material layer is formed by thick-film printing a paste containing an organic Ag compound. This paste containing an organic Ag compound contains an organic Ag compound, Pd, and a resin. The resin content is, for example, 60 to 80 wt%.

  Next, a second material layer is formed. The second material layer is formed by thick film printing of an Ag paste for thick film printing. For this thick film printing, the Ag paste contains Ag particles, glass frit, Pd, and resin. The resin content is, for example, 20 to 30 wt%. The first material layer and the second material layer constitute an Ag paste layer. Next, the Ag paste layer is baked to form a conductor layer mainly composed of Ag. Then, the electrode layer 3 having a configuration in which the first layer 31 and the second layer 32 are laminated is formed by patterning the conductor layer by, for example, etching.

  Next, as shown in FIG. 9, the resistor layer 4 is formed. The resistor layer 4 is formed by, for example, printing a thick film of a resistor paste containing a resistor such as ruthenium oxide and firing the resistor paste. After the formation of the resistor layer 4, trimming adjustment of the resistance value of the heat generating portion 41 is performed as necessary.

  Next, as shown in FIG. 10, the protective layer 5 is formed. The protective layer 5 is formed by, for example, applying a glass paste to a region where the protective layer 5 is to be formed by thick film printing and baking the glass paste. After that, the thermal print head A1 is obtained by mounting the drive IC 71, bonding the wire 61, attaching the substrate 1 and the wiring substrate 74 to the heat dissipation member 75, and the like.

  Next, the operation of the thermal print head A1 will be described.

  In the present embodiment, the substrate 1 is an aluminum nitride substrate whose main component is aluminum nitride, and the glaze layer 2 includes a crystallized glass layer 21 in contact with the substrate 1. The thermal conductivity of aluminum nitride, which is the main component of the substrate 1, is 80 to 180 W / (m · K), and the thermal conductivity (21 W / (21) of alumina, which is a general substrate material used in thermal print heads. It is much larger than about m · K). Therefore, when the substrate 1 is an aluminum nitride substrate (main component is aluminum nitride), the heat generated in the heat generating portion 41 can be quickly released through the substrate 1, and the heat dissipation is excellent. Therefore, it is possible to increase the printing speed of the printer in which the thermal print head A1 is incorporated.

  In addition, a crystallized glass layer 21 is formed on a portion of the glaze layer 2 formed on the substrate 1 in contact with the substrate 1. According to such a configuration, the fluidity of the glass during firing is suppressed, the reaction between the glass component and the component of the substrate 1 (aluminum nitride substrate) is suppressed as much as possible, and the occurrence of hole defects due to gas foaming is suppressed. be able to.

  The glaze layer 2 includes an amorphous glass layer 23 formed on the uppermost part farthest from the substrate 1. The electrode layer 3 is directly formed on the amorphous glass layer 23. Since the amorphous glass layer 23 is excellent in surface smoothness, the electrode layer 3 can be appropriately formed. Further, the thickness of the amorphous glass layer 23 is not less than the thickness of the crystallized glass layer 21, and preferably not less than 1.5 times the thickness of the crystallized glass layer 21. Thus, by increasing the thickness of the amorphous glass layer 23 within a practically possible range, the surface smoothness of the glaze layer 2 can be sufficiently ensured.

  The glaze layer 2 has a laminated structure in which a crystallized glass layer 21, a semi-crystallized glass layer 22, and an amorphous glass layer 23 are laminated in this order. A semi-crystallized glass layer 22 is interposed therebetween. As for the magnitude relationship of the thermal expansion coefficient of each layer of the glaze layer 2, the amorphous glass layer 23> the semi-crystallized glass layer 22> the crystallized glass layer 21 as described above. According to the configuration in which the semi-crystallized glass layer 22 is interposed between the crystallized glass layer 21 and the amorphous glass layer 23, the difference in thermal expansion coefficient between the crystallized glass layer 21 and the amorphous glass layer 23 is reduced. Inconveniences such as delamination in the glaze layer 2 can be avoided.

  The thickness of the glaze layer 2 is 60 to 120 μm, and the thickness of the glaze layer 2 as a whole is sufficiently ensured. According to such a configuration, the heat storage action by the glaze layer 2 is appropriately exhibited, and energy saving can be achieved for the printer in which the thermal print head A1 is incorporated.

  The amorphous glass layer 23 formed on the top of the glaze layer 2 is white or transparent. In the manufacture of the thermal print head A1, trimming adjustment of the resistance value of the resistor layer 4 (heat generating portion 41) and bonding of the wire 61 are performed by grasping the object by pattern recognition. In the pattern recognition, the wire 61 and the resistor layer 4 appear as dark colors. However, according to the configuration of this embodiment in which the uppermost layer of the glaze layer 2 is light (white), pattern recognition can be facilitated. Thus, trimming adjustment of the resistance value of the heat generating portion 41 and bonding of the wire 61 can be appropriately performed.

  The substrate 1 is made of aluminum nitride and an aluminum nitride composition (light opaque portion) containing carbon as a light opaque material that does not transmit light. Since aluminum nitride has translucency, detection by an optical sensor is possible if the substrate 1 of the present embodiment is configured by a light-impermeable portion. Therefore, the presence or absence of the substrate 1 can be detected by the optical sensor at the time of manufacturing the thermal print head A1. Note that, unlike the present embodiment, the light-impermeable portion may be formed of a coating film that is formed on the substrate 1 and contains a light-impermeable material that does not transmit light.

  The thermal print head according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the thermal print head according to the present invention can be varied in design in various ways.

A1 Thermal print head 1 Substrate 2 Glaze layer 21 Crystallized glass layer 22 Semi-crystallized glass layer 23 Amorphous glass layer 3 Electrode layer 31 First layer 32 Second layer 33 Common electrode 34 Common electrode strip portion 35 Connection portion 36 Individual Electrode 37 Connecting portion 38 Individual electrode strip portion 39 Bonding portion 4 Resistor layer 41 Heat generating portion 5 Protective layer 61 Wire 71 Drive IC
72 Sealing resin 73 Connector 74 Wiring board 75 Heat radiation member 81 Platen roller 82 Print medium x Main scanning direction y Sub-scanning direction z Thickness direction

Claims (20)

A substrate,
A glaze layer formed on the substrate;
An electrode layer formed on the glaze layer;
A resistor layer including a plurality of heat generating portions arranged in the main scanning direction,
The substrate is an aluminum nitride substrate mainly composed of aluminum nitride,
The glaze layer is a thermal print head including a crystallized glass layer in contact with the substrate.   The thermal print head according to claim 1, wherein the glaze layer includes an amorphous glass layer that is located farthest from the substrate and on which the electrode layer is directly formed.   The thermal print head according to claim 2, wherein the glaze layer includes a semi-crystallized glass layer interposed between the crystallized glass layer and the amorphous glass layer.   The thermal print head according to claim 2 or 3, wherein a thickness of the amorphous glass layer is equal to or greater than a thickness of the crystallized glass layer.   The thermal print head according to claim 4, wherein a thickness of the amorphous glass layer is 1.5 times or more a thickness of the crystallized glass layer.   The thermal print head according to claim 3, wherein a thickness of the crystallized glass layer is equal to or greater than a thickness of the semi-crystallized glass layer.   The thermal print head according to claim 1, wherein the glaze layer has a thickness of 60 to 120 μm.   The thermal print head according to claim 2, wherein the amorphous glass layer is white or transparent.   The thermal print head according to claim 1, wherein at least a part of the substrate has a light non-transmissive portion that does not transmit light.   The thermal print head according to claim 9, wherein the light-impermeable portion is made of an aluminum nitride composition containing aluminum nitride and a light-impermeable material that does not transmit light.   The thermal print head according to claim 10, wherein the light-impermeable material is carbon.   The thermal print head according to claim 9, wherein the light impermeable portion is formed of a coating film formed on the substrate and containing a light impermeable material that does not transmit light.   The electrode layer includes a common electrode having a connecting portion extending in the main scanning direction and a plurality of common electrode strips extending from the connecting portion in the sub-scanning direction, each extending in the sub-scanning direction and adjacent in the main scanning direction. The thermal print head according to claim 1, further comprising a plurality of individual electrodes each having an individual electrode strip portion positioned between the matching common electrode strip portions.   The thermal print head according to claim 13, wherein the resistor layer intersects the plurality of common electrode strips and the plurality of individual electrode strips.   The thermal print head according to claim 14, wherein the plurality of common electrode strips and the plurality of individual electrode strips are interposed between the substrate and the resistor layer.   16. The thermal print head according to claim 13, wherein the resistor layer has a strip shape extending long in the main scanning direction.   The thermal print head according to claim 16, wherein the resistor layer is a fired body of a resistor paste printed with a thick film.   The thermal print head according to claim 1, wherein the glaze layer covers at least a part of a surface on one side in the thickness direction of the substrate.   The thermal print head according to claim 18, wherein the glaze layer covers the entire surface of the substrate.   The thermal print head according to any one of claims 1 to 19, further comprising a protective layer covering the resistor layer.

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