Thermal printhead

Abstract

To provide a thermal print head that can suppress power consumption from increasing, by enhancing heat accumulation performance of a glaze layer.SOLUTION: A thermal print head A10 comprises: a substrate 1; a first glaze layer 21 covering at least a portion of the substrate 1; a resistor layer 3 including a plurality of heat generation parts positioned at the opposite side of the substrate 1 with the first glaze layer 21 as a reference in a first direction z; and a wiring layer 4 conducted to the plurality of heat generation parts and arranged to contact the resistor layer 3. The plurality of heat generation parts are arranged along a second direction that is orthogonal to the first direction z. The first glaze layer 21 contains a filler 211, and the filler 211 has a hollow part.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a thermal print head.

Background Art

[0002] A thermal print head is a main component of a thermal printer that prints on a recording medium such as thermal paper. Patent Document 1 discloses an example of a thermal print head. The thermal print head includes a substrate, a common electrode and a plurality of individual electrodes disposed on the substrate, and a heating resistor that conducts to the common electrode and the plurality of individual electrodes. Dot printing is performed on the recording medium by selectively heating the heating resistor when current is passed through the common electrode and the plurality of individual electrodes.

[0003] The thermal print head disclosed in Patent Document 1 further includes a glaze layer. The heating resistor is disposed on the glaze layer. When forming the common electrode and the plurality of individual electrodes adjacent to the heating resistor, the glaze layer prevents defects from occurring in these electrodes due to the surface roughness of the substrate. Further, the glaze layer has a function of temporarily storing heat generated by the heating resistor. Here, when the heat storage performance of the glaze layer deteriorates, the power consumption of the thermal print head increases. Particularly in cold regions, a decrease in the heat storage performance of the glaze layer is a concern. Therefore, in order to suppress an increase in the power consumption of the thermal print head, it is required to improve the heat storage property of the glaze layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the circumstances described above, the objective of this disclosure is to provide a thermal print head that can suppress an increase in power consumption by improving the heat storage performance of the glaze layer. [Means for solving the problem]

[0006] A thermal print head provided by this disclosure comprises a substrate, a first glaze layer covering at least a portion of the substrate, a resistor layer including a plurality of heating elements located on the opposite side of the substrate from the first glaze layer in a first direction, and a wiring layer that is electrically connected to the plurality of heating elements and arranged in contact with the resistor layer, wherein the plurality of heating elements are arranged along a second direction perpendicular to the first direction, and the first glaze layer contains a filler, the filler having a hollow portion. [Effects of the Invention]

[0007] The configuration of the thermal printhead according to this disclosure enhances the heat storage performance of the glaze layer, thereby suppressing an increase in the power consumption of the thermal printhead.

[0008] Other features and advantages of this disclosure will become more apparent from the detailed description below, based on the accompanying drawings. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a plan view of a thermal print head according to a first embodiment of the present disclosure. [Figure 2] Figure 2 is a bottom view of the thermal print head shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view taken along the line III-III in Figure 1. [Figure 4] Figure 4 is a partially enlarged plan view of the thermal print head shown in Figure 1. [Figure 5] Figure 5 is a magnified view of a portion of Figure 4. [Figure 6]Figure 6 is a cross-sectional view taken along line VI-VI of Figure 5. [Figure 7] Figure 7 is a cross-sectional view taken along line VII-VII of Figure 5. [Figure 8] Figure 8 is a partially enlarged view of Figure 6. [Figure 9] Figure 9 is a partially enlarged view of Figure 8. [Figure 10] Figure 10 is a partially enlarged view of Figure 5. [Figure 11] Figure 11 is a partially enlarged plan view of the thermal print head according to the second embodiment of the present disclosure. [Figure 12] Figure 12 is a cross-sectional view taken along line XII-XII of Figure 11. [Figure 13] Figure 13 is a cross-sectional view taken along line XIII-XIII of Figure 11. [Figure 14] Figure 14 is a cross-sectional view for explaining the manufacturing process of the thermal print head shown in Figure 11. [Figure 15] Figure 15 is a cross-sectional view for explaining the manufacturing process of the thermal print head shown in Figure 11. [Figure 16] Figure 16 is a cross-sectional view of the thermal print head according to a modification of the second embodiment of the present disclosure. [Figure 17] Figure 17 is a cross-sectional view of the thermal print head shown in Figure 16, and its cross-sectional position is different from that of Figure 16. [Figure 18] Figure 18 is a plan view of the thermal print head according to the third embodiment of the present disclosure. [Figure 19] Figure 19 is a plan view of the main part of the thermal print head shown in Figure 18. [Figure 20] Figure 20 is a partially enlarged view of Figure 19. [Figure 21] Figure 21 is a cross-sectional view taken along line XXI-XXI of Figure 18. [Figure 22] Figure 22 is a cross-sectional view of the main part of the thermal print head shown in Figure 18. [Figure 23] Figure 23 is a partially enlarged view of Figure 22. [Figure 24]FIG. 24 is a partially enlarged plan view of a main part of a thermal print head according to a fourth embodiment of the present disclosure. [Figure 25] FIG. 25 is a cross-sectional view taken along line XXV-XXV of FIG. 24. [Figure 26] FIG. 26 is a cross-sectional view taken along line XXVI-XXVI of FIG. 24. [Figure 27] FIG. 27 is a partially enlarged view of FIG. 25. [Figure 28] FIG. 28 is a partially enlarged view of FIG. 26. MODE FOR CARRYING OUT THE INVENTION

[0010] A mode for carrying out the present disclosure will be described based on the accompanying drawings.

[0011] [First Embodiment] Based on FIGS. 1 to 10, a thermal print head A10 according to a first embodiment of the present disclosure will be described. The thermal print head A10 includes a substrate 1, a first glaze layer 21, a resistor layer 3, a wiring layer 4, and a protective layer 5. Further, the thermal print head A10 includes a heat dissipation member 72, a plurality of drive elements 73, a sealing resin 76, and a connector 77. Here, in FIGS. 4 and 5, illustration of the protective layer 5 is omitted for convenience of understanding.

[0012] The thermal print head A10 shown in these figures is an electronic device that performs printing on a recording medium such as thermal paper by selectively generating heat in a plurality of heating portions 31 (details will be described later) included in the resistor layer 3. The resistor layer 3 is formed by printing and firing. Therefore, the thermal print head A10 is a so-called thick film type.

[0013] For the sake of explanation, the direction normal to the main surface 11 of the substrate 1, which will be described later, will be called the "first direction z". The direction perpendicular to the first direction z will be called the "second direction x". The second direction x corresponds to the main scanning direction of the thermal print head A10. The direction perpendicular to both the first direction z and the second direction x will be called the "third direction y". The third direction y corresponds to the sub-scanning direction of the thermal print head A10.

[0014] Substrate 1 extends in the second direction x, as shown in Figures 1 and 2. The composition of substrate 1 includes alumina (Al2O3). Substrate 1 is a ceramic made of a material including alumina and a resin binder. In addition to these, the material of substrate 1 may also include a light-shielding material. This light-shielding material is, for example, carbon (C).

[0015] As shown in Figures 6 and 7, the substrate 1 has a main surface 11 and a back surface 12. The main surface 11 and the back surface 12 face opposite each other in the first direction z. The main surface 11 faces the first glaze layer 21.

[0016] As shown in Figures 6 and 7, the first glaze layer 21 covers at least a portion of the substrate 1. In the thermal print head A10, the first glaze layer 21 covers the entire main surface 11 of the substrate 1. The first glaze layer 21 is formed by screen printing a paste containing amorphous glass onto the main surface 11 of the substrate 1, and then firing the paste. The amorphous glass is, for example, an SiO2-BaO-Al2O3-SnO-ZnO type glass. Therefore, the first glaze layer 21 is transparent or white. The glass transition temperature of the first glaze layer 21 is approximately 680°C.

[0017] As shown in Figure 8, the first glaze layer 21 contains filler 211. As shown in Figure 9, the filler 211 has a hollow portion 211A and a shell portion 211B. The hollow portion 211A is a vacuum. The shell portion 211B surrounds the hollow portion 211A. The composition of the shell portion 211B includes silicon dioxide (SiO2). The particle size D of the filler 211 is between 0.3 μm and 0.5 μm. The weight percentage (wt%) of the filler 211 relative to the first glaze layer 21 is between 30% and 80%.

[0018] As shown in Figures 5 and 6, the wiring layer 4 is in contact with the resistor layer 3. The wiring layer 4 constitutes a conductive path for supplying current to the resistor layer 3. In the thermal print head A10, the wiring layer 4 is in contact with the first glaze layer 21. The wiring layer 4 includes a common wiring 41 and a plurality of individual wirings 42. The common wiring 41 is conductive to a plurality of heat-generating parts 31. The plurality of individual wirings 42 are individually conductive to a plurality of heat-generating parts 31. In the thermal print head A10, current flows from the common wiring 41 through the plurality of heat-generating parts 31 to the plurality of individual wirings 42. Therefore, the common wiring 41 is the positive electrode, and the plurality of individual wirings 42 are the negative electrodes. An example of the material for the wiring layer 4 is a resinate paste mainly composed of gold (Au). The wiring layer 4 is formed by screen printing the resinate paste onto the first glaze layer 21, firing the paste, and then performing photolithography patterning and etching on the paste. An example of the thickness range for wiring layer 4 is 0.6 μm to 1.2 μm.

[0019] As shown in Figure 4, the common wiring 41 has a base 411 and a plurality of extensions 412. The base 411 is located on one side of the third direction y with respect to the resistor layer 3 in the third direction y. The base 411 extends in the second direction x and away from the third direction y.

[0020] As shown in Figures 4 and 5, the multiple extensions 412 extend from the base 411 toward the resistor layer 3 in the third direction y. The multiple extensions 412 are arranged at equal intervals along the second direction x.

[0021] As shown in Figure 4, each of the multiple individual wirings 42 has a base portion 421 and an extension portion 422. The multiple individual wirings 42 are arranged on the substrate 1 in bundles corresponding to each of the multiple drive elements 73. The multiple individual wirings 42 apply voltage to each of the multiple heat-generating components 31 individually.

[0022] As shown in Figure 4, the base portion 421 is located in the third direction y, with respect to the resistor layer 3, on the opposite side from the base portion 411 of the common wiring 41. The base portions 421 of each of the multiple individual wirings 42 form two rows that are separated from each other in the third direction y. Each of these two rows is arranged along the second direction x. In the row of the two rows that is closest to the resistor layer 3, an extension portion 422 is located between two adjacent base portions 421.

[0023] As shown in Figure 4, the extension 422 is connected to the base 421. Furthermore, the extension 422 includes a first part 422A, a second part 422B, and a third part 422C.

[0024] As shown in Figures 4 and 5, the first part 422A extends in the third direction y. The first parts 422A are arranged at equal intervals along the second direction x. Of the multiple extensions 412 of the common wiring 41, the first part 422A is located between two adjacent extensions 412 in the second direction x.

[0025] As shown in Figures 4 and 5, the second part 422B is connected to the first part 422A. The second part 422B of each extension 422 of the multiple individual wirings 42 is mostly inclined with respect to the third direction y.

[0026] As shown in Figures 4 and 5, the third part 422C is located opposite the first part 422A with respect to the second part 422B in the third direction y. The third part 422C is connected to the second part 422B and the base 411. The third part 422C extends in the third direction y.

[0027] As shown in Figure 4, in one bundle of multiple individual wirings 42 corresponding to each of the multiple drive elements 73, when comparing the boundary position between the second part 422B and the third part 422C on the second direction x side, a shift ΔL occurs in the third direction y.

[0028] As shown in Figures 1 and 4, the resistive layer 3 extends in the second direction x. As shown in Figures 5 and 6, the resistive layer 3 is in contact with the first glaze layer 21. The resistive layer 3 intersects with the multiple extensions 412 of the common wiring 41 and with the first portion 422A of each extension 422 of the multiple individual wirings 42. The resistive layer 3 covers a portion of each of the multiple extensions 412 and a portion of the first portion 422A of each extension 422 of the multiple individual wirings 42. In the thermal print head A10, the resistive layer 3 straddles the multiple extensions 412 and the first portion 422A of each extension 422 of the multiple individual wirings 42.

[0029] In the resistive layer 3, the region sandwiched between the portion covering one of the multiple extensions 412 and the portion covering one of the first parts 422A of the multiple individual wirings 42 located adjacent to that portion in the second direction x is designated as one of the multiple heat-generating portions 31. As shown in Figure 4, the multiple heat-generating portions 31 are arranged along the second direction x. The multiple heat-generating portions 31 are located on the opposite side of the substrate 1 from the first glaze layer 21 in the first direction z. By selectively energizing the wiring layer 4, the multiple heat-generating portions 31 are selectively heated. This results in dot printing on the recording medium shown in Figure 3. The material for the resistive layer 3 is selected to have a higher electrical resistivity than the wiring layer 4. An example of the material for the resistive layer 3 is a conductive paste containing ruthenium oxide (RuO2) particles and glass frit. The resistive layer 3 is formed by screen printing the conductive paste onto the first glaze layer 21 and then firing the paste. The maximum thickness of the resistive layer 3 is 6 μm to 10 μm.

[0030] As shown in Figure 10, when viewed in the first direction z, the multiple heat-generating parts 31 overlap the filler 211 of the first glaze layer 21.

[0031] As shown in Figures 6 and 7, the protective layer 5 is in contact with the first glaze layer 21. The protective layer 5 covers multiple heat-generating parts 31. Furthermore, the protective layer 5 covers a portion of the wiring layer 4. In the thermal print head A10, the wiring layer 4 is covered by the protective layer 5, except for a portion of the common wiring 41 connected to the base 411 and the base 421 of each of the multiple individual wirings 42.

[0032] The protective layer 5, like the first glaze layer 21, is made of a material containing amorphous glass. The protective layer 5 is formed by screen printing a paste containing amorphous glass onto the first glaze layer 21, the resistor layer 3, and a portion of the wiring layer 4, and then firing the paste.

[0033] As shown in Figure 3, the heat dissipation member 72 is located on the opposite side of the first glaze layer 21 from the substrate 1 in the first direction z. The back surface 12 of the substrate 1 is bonded to the heat dissipation member 72 via a bonding material (not shown). The composition of the heat dissipation member 72 includes, for example, aluminum (Al).

[0034] As shown in Figures 1 and 3, the multiple drive elements 73 are located on the other side of the third direction y relative to the resistive layer 3. The drive elements 73 are mounted on the substrate 1. Multiple electrodes (not shown) are provided on the upper surface of the drive element 73. Multiple first wires 74, which are conductively joined to the bases 421 of multiple individual wirings 42 corresponding to the drive element 73, are conductively joined to some of the multiple electrodes. As a result, the drive element 73 is electrically connected to the multiple individual wirings 42 corresponding to it. Multiple second wires 75, which are conductively joined to wirings arranged on the substrate 1, are connected to the other multiple pads. The drive element 73 selectively energizes the multiple individual wirings 42 via the multiple first wires 74. As a result, multiple heat-generating parts 31 selectively generate heat. Alternatively, the drive element 73 may be mounted on a wiring board that is separated from the substrate 1 in the third direction y and supported by a heat dissipation member 72. Such a wiring board is, for example, a PCB (Printed Circuit Board).

[0035] As shown in Figure 3, the sealing resin 76 covers the multiple drive elements 73, the multiple first wires 74, and the multiple second wires 75. In addition to these, the sealing resin 76 further covers some areas of the multiple individual wirings 42 (such as the multiple bases 421) that are not covered by the protective layer 5. The sealing resin 76 is, for example, a black, flexible synthetic resin used for underfill. Alternatively, the sealing resin 76 may be a black, rigid synthetic resin.

[0036] As shown in Figures 1 to 3, the connector 77 is located in the third direction y on the opposite side of the resistive layer 3 from the multiple drive elements 73. In the thermal print head A10, the connector 77 is attached to the end of the substrate 1 in the third direction y. The connector 77 is connected to the thermal printer. The connector 77 has multiple pins (not shown). Some of these multiple pins are electrically connected to wiring (not shown) on the substrate 1 to which multiple second wires 75 are electrically joined. Furthermore, another portion of these multiple pins are electrically connected to wiring (not shown) on the substrate 1 that is electrically connected to the base 411 of the common wiring 41. As a result, a constant voltage is applied to the common wiring 41 from the outside via the connector 77.

[0037] Next, we will explain the operation of the thermal print head A10.

[0038] As shown in Figure 3, the multiple heat-generating elements 31 of the thermal print head A10 face the platen roller 79 incorporated into the thermal printer via a protective layer 5. The platen roller 79 is a roller-shaped mechanism for feeding the recording medium. The recording medium is sandwiched between the area of ​​the protective layer 5 covering the multiple heat-generating elements 31 and the platen roller 79. When the thermal printer is in operation, the platen roller 79 rotates, feeding the recording medium at a constant speed in the third direction y. At this time, when the multiple heat-generating elements 31 selectively generate heat, the heat is transferred to the recording medium via the protective layer 5, thereby printing on the recording medium. Simultaneously, the heat generated from the multiple heat-generating elements 31 is also transferred to the first glaze layer 21. A portion of the heat transferred to the first glaze layer 21 is stored in the first glaze layer 21. The remaining heat is released to the outside of the thermal print head A10 via the substrate 1 and the heat dissipation member 72.

[0039] Next, we will explain the effects and benefits of the thermal print head A10.

[0040] The first glaze layer 21 of the thermal print head A10 covers at least a portion of the substrate 1. The multiple heat-generating parts 31 of the resistor layer 3 are located on the opposite side of the substrate 1 from the first glaze layer 21 in the first direction z. The first glaze layer 21 contains a filler 211. The filler 211 has a hollow portion 211A. This configuration further reduces the thermal conductivity of the first glaze layer 21. Therefore, the heat transferred from the multiple heat-generating parts 31 to the first glaze layer 21 remains in the first glaze layer 21 for a longer time, thus increasing the heat storage performance of the first glaze layer 21. Consequently, with this configuration, the heat storage performance of the glaze layer in the thermal print head A10 is enhanced, making it possible to suppress an increase in the power consumption of the thermal print head A10.

[0041] Viewed in the first direction z, the multiple heat-generating elements 31 overlap the filler 211. By adopting this configuration, the heat storage capacity of the first glaze layer 21 can be efficiently increased.

[0042] The filler 211 has a shell portion 211B surrounding a hollow portion 211A. The hollow portion 211A is a vacuum. By adopting this configuration, when firing the paste containing amorphous glass that will become the first glaze layer 21, it is possible to prevent the filler 211 from bursting due to the thermal expansion of the hollow portion 211A.

[0043] The composition of the shell portion 211B of the filler 211 includes silicon dioxide. By adopting this configuration, the coefficient of thermal expansion of the filler 211 becomes approximately equal to that of the first glaze layer 21. As a result, the generation of thermal stress at the interface between the filler 211 and the first glaze layer 21 is reduced, thereby preventing the formation of cracks in the first glaze layer 21.

[0044] By improving the heat storage performance of the first glaze layer 21, the thickness of the first glaze layer 21 can be made thinner without impairing its heat storage performance. With this configuration, when screen printing the paste containing amorphous glass that will become the first glaze layer 21 onto the main surface 11, the surface tension caused by the emulsion etc. located around the paste is reduced. As a result, the first glaze layer 21 becomes flatter.

[0045] The thermal print head A10 is further equipped with a protective layer 5 that covers multiple heat-generating elements 31. This configuration further reduces the frictional resistance of the recording medium to the thermal print head A10.

[0046] The thermal print head A10 further includes a heat dissipation member 72 located on the opposite side of the first glaze layer 21 from the substrate 1 in the first direction z. The substrate 1 is bonded to the heat dissipation member 72. This configuration suppresses excessive temperature rise of the first glaze layer 21, thereby preventing a decrease in print quality.

[0047] [Second Embodiment] A thermal print head A20 according to a second embodiment of this disclosure will be described based on Figures 11 to 13. In these figures, elements that are the same as or similar to those in the thermal print head A10 described above are denoted by the same reference numerals, and redundant explanations are omitted. Here, for ease of understanding, the protective layer 5 is not shown in Figure 11.

[0048] In thermal printhead A20, the configuration of the first glaze layer 21 and the inclusion of a second glaze layer 22 differ from those of thermal printhead A10 mentioned above.

[0049] As shown in Figures 12 and 13, the second glaze layer 22 covers a portion of the main surface 11 of the substrate 1. The second glaze layer 22 is formed by screen printing a paste containing quasicrystalline (semicrystalline) glass onto the main surface 11 of the substrate 1, and then firing the paste. The quasicrystalline glass is, for example, an SiO2-B2O3-Al2O3-ZrO2 type glass. Therefore, the second glaze layer 22 is white in color. The glass transition temperature of the second glaze layer 22 is approximately 740°C. Consequently, the glass transition temperature of the first glaze layer 21 is lower than that of the second glaze layer 22.

[0050] As shown in Figures 11 to 13, the second glaze layer 22 is located on both sides of the first glaze layer 21 in the third direction y. The second glaze layer 22 has a base surface 221 facing away from the side facing the substrate 1 in the first direction z. Furthermore, the second glaze layer 22 has an opening 22A that penetrates in the first direction z. The opening 22A extends in the second direction x. The main surface 11 of the substrate 1 is exposed at the opening 22A.

[0051] As shown in Figures 12 and 13, at least a portion of the first glaze layer 21 is contained within the opening 22A of the second glaze layer 22. The first glaze layer 21 is in contact with the main surface 11 of the substrate 1. The base surface 221 of the second glaze layer 22 includes a pair of edges 221A that sandwich the first glaze layer 21. The first glaze layer 21 is in contact with the pair of edges 221A.

[0052] As shown in Figures 12 and 13, in the thermal print head A20, the first glaze layer 21 protrudes from the base surface 221 of the second glaze layer 22. Viewed in the second direction x, the periphery of the portion of the first glaze layer 21 that protrudes from the base surface 221 forms a convex curve.

[0053] Next, based on Figures 14 and 15, the method for forming the first glaze layer 21 and the second glaze layer 22 in the manufacturing method of the thermal print head A20 will be described. The cross-sectional positions in Figures 14 and 15 are the same as those in Figure 12.

[0054] First, as shown in Figure 14, a second glaze layer 22 is formed that covers a portion of the main surface 11 of the substrate 1. The second glaze layer 22 is formed by screen printing a paste containing quasicrystalline glass onto the main surface 11 of the substrate 1, and then firing the paste. During screen printing, an emulsion or the like is applied to the main surface 11 so that an opening 22A is formed in the second glaze layer 22.

[0055] Next, as shown in Figure 15, the first glaze layer 21 is formed. In forming the first glaze layer 21, a paste containing amorphous glass is applied to the opening 22A of the second glaze layer 22 using a dispenser. The paste contains a filler 211. After that, the paste is fired. The firing temperature is adjusted so as not to exceed the glass transition temperature of the second glaze layer 22. Thus, the first glaze layer 21 and the second glaze layer 22 are formed.

[0056] <Variation> Based on Figures 16 and 17, a modified example of thermal printhead A20, thermal printhead A21, will be described. Thermal printhead A21 differs from thermal printhead A20 in the configuration of the first glaze layer 21.

[0057] As shown in Figures 16 and 17, the first glaze layer 21 is flush with the base surface 221 of the second glaze layer 22. The thickness of the first glaze layer 21 is equal to the thickness of the second glaze layer 22.

[0058] Next, we will explain the effects and benefits of the A20 thermal printhead.

[0059] The first glaze layer 21 of the thermal print head A20 covers at least a portion of the substrate 1. The multiple heat-generating parts 31 of the resistor layer 3 are located on the opposite side of the substrate 1 from the first glaze layer 21 in the first direction z. The first glaze layer 21 contains a filler 211. The filler 211 has a hollow portion 211A. Therefore, with this configuration, the heat storage performance of the glaze layer is enhanced in the thermal print head A20, making it possible to suppress the increase in power consumption of the thermal print head A20. Furthermore, by having a configuration common to the thermal print head A10, the thermal print head A20 achieves the same effects as the thermal print head A10.

[0060] The thermal print head A20 further includes a second glaze layer 22 located on both sides of the first glaze layer 21 in the third direction y. The base surface 221 of the second glaze layer 22 includes a pair of edges 221A that sandwich the first glaze layer 21. The first glaze layer 21 is in contact with the pair of edges 221A. This configuration prevents the volume of the first glaze layer 21 from being excessively reduced. This makes it possible to reduce the material cost of the first glaze layer 21 required for manufacturing the thermal print head A20 while ensuring the functionality of the first glaze layer 21.

[0061] In the thermal print head A20, the first glaze layer 21 protrudes from the base surface 221 of the second glaze layer 22. Furthermore, when viewed in the second direction x, the periphery of the portion of the first glaze layer 21 that protrudes from the base surface 221 forms a convex curve. By adopting this configuration, when printing on the recording medium, the contact area between the thermal print head A20 and the recording medium can be minimized while heat from the multiple heat-generating parts 31 can be transferred to the recording medium. This further improves print quality.

[0062] [Third Embodiment] A thermal print head A30 according to a third embodiment of this disclosure will be described based on Figures 18 to 23. In these figures, elements that are the same as or similar to those in the thermal print head A10 described above are denoted by the same reference numerals, and redundant explanations are omitted.

[0063] The thermal print head A30 is composed of a main part and an auxiliary part. The main part of the thermal print head A30 comprises a substrate 1, an insulating layer 23, a resistive layer 3, a wiring layer 4, and a protective layer 5. The auxiliary part of the thermal print head A30 comprises a wiring board 71, a heat dissipation member 72, a plurality of drive elements 73, a plurality of first wires 74, a plurality of second wires 75, a sealing resin 76, and a connector 77. In Figure 18, for ease of understanding, the protective layer 5, the plurality of first wires 74, the plurality of second wires 75, and the sealing resin 76 are omitted from the illustration. In Figures 19 and 20, for ease of understanding, the protective layer 5 is omitted from the illustration.

[0064] In the thermal print head A30, as shown in Figure 21, the substrate 1, which forms the main part of the thermal print head A30, is bonded to the heat dissipation member 72. Furthermore, the wiring board 71 is located next to the substrate 1 in the third direction y. The wiring board 71 is also bonded to the heat dissipation member 72, just like the substrate 1. On the substrate 1, a plurality of heat-generating parts 31 are formed, which form part of the resistive layer 3 and are arranged along the second direction x. The plurality of heat-generating parts 31 are selectively heated by a plurality of drive elements 73 mounted on the wiring board 71. The plurality of drive elements 73 are driven according to a printing signal transmitted from the outside via a connector 77.

[0065] As shown in Figure 18, the substrate 1 is rectangular in shape, extending in the second direction x when viewed in the first direction z. The substrate 1 contains a semiconductor material. This semiconductor material contains a single crystal material composed of silicon (Si).

[0066] As shown in Figure 21, in the thermal print head A30, the main surface 11 faces the platen roller 79, and the back surface 12 faces the heat dissipation member 72. The plane orientation of the main surface 11 based on the crystal structure of the substrate 1 is the (100) plane.

[0067] As shown in Figure 22, the substrate 1 has a protrusion 13. The protrusion 13 projects from the main surface 11 in a first direction z. As shown in Figures 18 and 19, the protrusion 13 extends in a second direction x. The protrusion 13 is formed on the substrate 1 by anisotropic etching using a potassium hydroxide (KOH) solution.

[0068] As shown in Figures 22 and 23, the protrusion 13 has a top surface 130, a first inclined surface 131, and a second inclined surface 132. The top surface 130, the first inclined surface 131, and the second inclined surface 132 extend in the second direction x. The top surface 130 faces the first direction z and is located away from the main surface 11. The first inclined surface 131 and the second inclined surface 132 are located between the main surface 11 and the top surface 130. In the thermal print head A30, the first inclined surface 131 and the second inclined surface 132 are connected to the main surface 11 and the top surface 130. The first inclined surface 131 and the second inclined surface 132 are located away from each other in the third direction y. The first inclined surface 131 and the second inclined surface 132 are inclined with respect to the main surface 11. The first inclined surface 131 and the second inclined surface 132 are closer to each other as you move from the main surface 11 towards the top surface 130. The inclination angles α of the first inclined surface 131 and the second inclined surface 132 with respect to the main surface 11 are equal to each other.

[0069] The first glaze layer 21 covers the top surface 130 of the protrusion 13. When viewed in the second direction x, the periphery of the portion of the first glaze layer 21 on the side where the multiple heat-generating parts 31 are located in the first direction z, relative to the top surface 130, forms a convex curve.

[0070] As shown in Figures 22 and 23, the insulating layer 23 covers the main surface 11 of the substrate 1, the first inclined surface 131 and the second inclined surface 132 of the protrusion 13, and the first glaze layer 21. The insulating layer 23 is located between the substrate 1 and the wiring layer 4. The insulating layer 23 electrically insulates the substrate 1 from the resistor layer 3 and the wiring layer 4. The insulating layer 23 is made of silicon dioxide, for example, tetraethyl orthosilicate (TEOS) as a raw material. An example of the thickness of the insulating layer 23 is 1 μm to 15 μm. The thermal conductivity of the insulating layer 23 is higher than that of the first glaze layer 21.

[0071] As shown in Figures 22 and 23, the resistive layer 3 is positioned on the main surface 11 and protrusions 13 of the substrate 1. The resistive layer 3 is in contact with the insulating layer 23. As a result, in the thermal print head A30, the insulating layer 23 is sandwiched between the substrate 1 and the resistive layer 3. The resistive layer 3 is made of, for example, tantalum nitride (TaN). An example of the thickness of the resistive layer 3 is 0.02 μm to 0.1 μm.

[0072] As shown in Figures 19, 20, and 23, the resistive layer 3 includes a plurality of heat-generating parts 31. In the resistive layer 3, the plurality of heat-generating parts 31 are portions exposed from the wiring layer 4. By selectively energizing the plurality of heat-generating parts 31 from the wiring layer 4, the plurality of heat-generating parts 31 locally heat the recording medium. The plurality of heat-generating parts 31 are arranged along a second direction x. Of the plurality of heat-generating parts 31, two adjacent heat-generating parts 31 in the second direction x are located apart from each other. The plurality of heat-generating parts 31 are formed in contact with the insulating layer 23. In the thermal print head A30, the plurality of heat-generating parts 31 are formed on the top surface 130 of the protrusion 13 of the substrate 1. The plurality of heat-generating parts 31 are located in the center of the top surface 130 in a third direction y. As shown in Figure 21, the plurality of heat-generating parts 31 face the platen roller 79.

[0073] As shown in Figures 22 and 23, the wiring layer 4 is positioned in contact with the resistor layer 3. The wiring layer 4 is electrically connected to multiple heat-generating parts 31 of the resistor layer 3. The electrical resistivity of the wiring layer 4 is lower than that of the resistor layer 3. The wiring layer 4 is a metal layer made of, for example, copper (Cu). An example of the thickness of the wiring layer 4 is 0.3 μm to 2.0 μm. Alternatively, the wiring layer 4 may consist of two metal layers: a titanium (Ti) layer laminated on the resistor layer 3 and a copper layer laminated on top of the titanium layer. In this case, an example of the thickness of the titanium layer is 0.1 μm to 0.2 μm. As shown in Figure 18, the wiring layer 4 is located away from the periphery of the main surface 11 of the substrate 1.

[0074] As shown in Figure 18, the wiring layer 4 includes a common wiring 41 and a plurality of individual wirings 42. The common wiring 41 is located in the third direction y on the opposite side of the plurality of drive elements 73 with respect to the plurality of heat-generating parts 31 of the resistor layer 3. The plurality of individual wirings 42 are located in the third direction y on the opposite side of the common wiring 41 with respect to the plurality of heat-generating parts 31. The common wiring 41 is electrically connected to the plurality of heat-generating parts 31. The plurality of individual wirings 42 are electrically connected to the plurality of heat-generating parts 31 individually.

[0075] As shown in Figures 19 and 20, the common wiring 41 has a base 411 and a plurality of extensions 412 connected to the base 411. The base 411 is located in a third direction y, on the opposite side of the plurality of heating elements 31 of the resistor layer 3, with respect to the plurality of extensions 412. The base 411 is a strip extending in a second direction x. The plurality of extensions 412 are strips extending in a third direction y toward the plurality of heating elements 31 from the end of the base 411 facing the protrusion 13 of the substrate 1. The plurality of extensions 412 are arranged along the second direction x. A portion of each of the plurality of extensions 412 is located on the second inclined surface 132 of the protrusion 13. In the common wiring 41, current flows from the base 411 to the plurality of heating elements 31 via the plurality of extensions 412.

[0076] As shown in Figures 19 and 20, each of the multiple individual wirings 42 has a base 421 and an extension 422 connected to the base 421. The base 421 is located in the third direction y on the opposite side of the multiple heat-generating parts 31 of the resistor layer 3 with respect to the extension 422. The base 421 of each of the multiple individual wirings 42 forms two rows that are separated from each other in the third direction y. Each of the two rows is arranged along the second direction x. In the row of the two rows that is closest to the multiple heat-generating parts 31, the extension 422 is located between two adjacent bases 421.

[0077] As shown in Figures 19 and 20, the extension portion 422 is a strip-shaped extension in a third direction y toward the plurality of heating elements 31 from the end of the base portion 421 facing the protrusion portion 13 of the substrate 1. Each extension portion 422 of the plurality of individual wirings 42 is arranged along the second direction x. A portion of each extension portion 422 of the plurality of individual wirings 42 is located on the first inclined surface 131 of the protrusion portion 13. In each of the plurality of individual wirings 42, current flows from one of the plurality of heating elements 31 to the base portion 421 via the extension portion 422. Viewed in the first direction z, each of the plurality of heating elements 31 is sandwiched between the extension portion 422 of one of the plurality of individual wirings 42 and one of the plurality of extension portions 412 of the common wiring 41. The configuration of the wiring layer 4 and the plurality of heating elements 31 shown in Figures 19 and 20 is an example. Therefore, the configuration of the wiring layer 4 and the plurality of heat-generating elements 31 in this disclosure is not limited to the configurations shown in Figures 19 and 20.

[0078] As shown in Figure 22, the protective layer 5 covers a portion of the insulating layer 23, multiple heat-generating parts 31 of the resistor layer 3, and the wiring layer 4. The protective layer 5 has electrical insulating properties. The composition of the protective layer 5 includes silicon. For example, the protective layer 5 consists of either silicon dioxide or silicon nitride (Si3N4). Alternatively, the protective layer 5 may be a laminate composed of multiple types of these materials. The platen roller 79 shown in Figure 21 presses the recording medium against the portion of the protective layer 5 that covers the multiple heat-generating parts 31.

[0079] As shown in Figure 22, the protective layer 5 has a wiring opening 5A. The wiring opening 5A penetrates the protective layer 5 in the first direction z. The base 421 of each of the multiple individual wires 42 and a portion of the extension 422 of each of the multiple individual wires 42 are exposed through the wiring opening 5A.

[0080] As shown in Figure 21, the wiring board 71 is located next to the substrate 1 in the third direction y. As shown in Figure 18, in the first direction z, the multiple individual wirings 42 are located between the multiple heat-generating parts 31 of the resistor layer 3 and the wiring board 71 in the third direction y. In the first direction z, the area of ​​the wiring board 71 is larger than the area of ​​the substrate 1. Furthermore, in the first direction z, the wiring board 71 is rectangular with the second direction x as its longitudinal direction. The wiring board 71 is, for example, a PCB substrate. Multiple drive elements 73 and connectors 77 are mounted on the wiring board 71.

[0081] As shown in Figure 21, the heat dissipation member 72 faces the back surface 12 of the substrate 1. The back surface 12 is joined to the heat dissipation member 72. The wiring board 71 is joined to the heat dissipation member 72 by fasteners such as screws. When the thermal print head A30 is in use, some of the heat generated from the multiple heat-generating parts 31 of the resistive layer 3 is conducted to the heat dissipation member 72 via the substrate 1. The heat conducted to the heat dissipation member 72 is dissipated to the outside. The heat dissipation member 72 is made of, for example, aluminum (Al).

[0082] As shown in Figures 18 and 21, the multiple drive elements 73 are mounted on the wiring board 71 via an electrically insulating die bonding material (not shown). The multiple drive elements 73 are semiconductor elements configured with various circuits. One end of a plurality of first wires 74 and one end of a plurality of second wires 75 are electrically joined to the multiple drive elements 73. The other ends of the plurality of first wires 74 are electrically joined to the base 421 of each of the plurality of individual wirings 42. The other ends of the plurality of second wires 75 are electrically joined to wiring (not shown) provided on the wiring board 71 and electrically connected to the connector 77.

[0083] As described above, electrical signals for printing and electrical signals for controlling the multiple drive elements 73 are input to the multiple drive elements 73 from the outside via the connector 77. Based on these electrical signals, the multiple drive elements 73 selectively apply voltage to the multiple individual wirings 42. Furthermore, a constant voltage is applied to the common wiring 41 from the outside via the connector 77. In this case, a potential difference is generated between the common wiring 41 and any of the multiple individual wirings 42, causing the multiple heat-generating parts 31 of the resistive layer 3 to generate heat selectively.

[0084] As shown in Figure 21, the sealing resin 76 covers the multiple drive elements 73, the multiple first wires 74, and the multiple second wires 75. Furthermore, the sealing resin 76 covers a portion of each of the insulating layer 23 and the wiring board 71, and a portion of each of the multiple individual wirings 42.

[0085] As shown in Figures 18 and 21, the connector 77 is attached to the end of the wiring board 71 in the third direction y. The connector 77 has a plurality of pins (not shown). Some of these pins are electrically connected to a wiring (not shown) on the wiring board 71 to which a plurality of second wires 75 are electrically joined. Furthermore, another portion of these pins are electrically connected to a wiring (not shown) on the wiring board 71 that is electrically connected to the base 411 of the common wiring 41.

[0086] Next, we will explain the effects and benefits of the A30 thermal printhead.

[0087] The first glaze layer 21 of the thermal print head A30 covers at least a portion of the substrate 1. The multiple heat-generating parts 31 of the resistor layer 3 are located on the opposite side of the substrate 1 from the first glaze layer 21 in the first direction z. The first glaze layer 21 contains a filler 211. The filler 211 has a hollow portion 211A. Therefore, with this configuration, the heat storage performance of the glaze layer is enhanced in the thermal print head A30, making it possible to suppress the increase in power consumption of the thermal print head A30. Furthermore, by having a configuration common to the thermal print head A10, the thermal print head A30 achieves the same effects as the thermal print head A10.

[0088] In the thermal print head A30, the substrate 1 has a protrusion 13 that projects from the main surface 11 in a first direction z. The first glaze layer 21 covers the top surface 130 of the protrusion 13. With this configuration, the multiple heat-generating elements 31 are located on the protrusion 13. This allows heat from the multiple heat-generating elements 31 to be transferred to the recording medium while minimizing the contact area between the thermal print head A30 and the recording medium during printing. Therefore, the print quality on the recording medium is improved.

[0089] The thermal print head A30 further comprises an insulating layer 23 that covers the main surface 11 of the substrate 1, the first inclined surface 131 and the second inclined surface 132 of the protrusion 13, and the first glaze layer 21. The insulating layer 23 is located between the substrate 1 and the wiring layer 4. By adopting this configuration, electrical insulation can be achieved between the substrate 1 and the resistor layer 3 and the wiring layer 4, even if the substrate 1 contains semiconductor material. Furthermore, by setting the thermal conductivity of the insulating layer 23 higher than that of the first glaze layer 21, the loss of heat conducted from the multiple heat-generating parts 31 to the first glaze layer 21 can be suppressed.

[0090] [Fourth Embodiment] A thermal print head A40 according to the fourth embodiment of this disclosure will be described based on Figures 24 to 28. In these figures, elements that are the same as or similar to those in the thermal print head A10 described above are denoted by the same reference numerals, and redundant explanations are omitted. Here, for the sake of ease of understanding, Figure 24 omits the illustration of the first protective layer 51 and the second protective layer 52, which will be described later, and the protective member 45 of the wiring layer 4, which will be described later.

[0091] Thermal print head A40 differs from thermal print head A30 mentioned above in the configuration of the substrate 1 and wiring layer 4, the inclusion of a first protective layer 51 and a second protective layer 52 instead of the protective layer 5, and the absence of an insulating layer 23. Thermal print head A40 is a so-called thin-film type.

[0092] Substrate 1 contains ceramics with relatively high thermal conductivity, such as AlN (aluminum nitride) or Al2O3 (alumina). Therefore, substrate 1 has electrical insulating properties.

[0093] As shown in Figures 24 to 26, the first glaze layer 21 is in contact with the main surface 11 of the substrate 1. The first glaze layer 21 extends along the x-direction and bulges in the z-direction in a cross-section with the y-direction and z-direction as in-plane directions. The first glaze layer 21 may be formed over the entire main surface 11, similar to the configuration of the thermal print head A10.

[0094] As shown in Figure 24, the common wiring 41 has a base portion 411 and an extension portion 412, as well as a bypass portion 413. The bypass portion 413 is connected to one side of the base portion 411 in the x-direction and extends from the base portion 411 in the y-direction toward the side where the multiple individual wirings 42 are located.

[0095] As shown in Figure 24, the wiring layer 4 includes a grounding section 43. The grounding section 43 is rectangular when viewed along the z-direction. In the y-direction, the grounding section 43 is located between the bypass section 413 of the common wiring 41 and the multiple individual wirings 42. The grounding section 43 is electrically connected to a ground terminal located inside the connector 77. As shown in Figure 26, the grounding section 43 has a connection section 431 and an extension section 432. The composition of the connection section 431 is the same as that of the common wiring 41 and the multiple individual wirings 42. The composition of the extension section 432 is the same as that of the resistor layer 3. As shown in Figure 28, one end of a first wire 74 is connected to the connection section 431, and the other end of the first wire 74 is connected to a second wiring section 712 located on the main surface 11 of the substrate 1. The second wiring section 712 is electrically connected to a ground terminal located inside the connector 77. Viewed along the z-direction, the extension portion 432 extends from the connecting portion 431 toward the side in the y-direction where the multiple heat-generating portions 31 of the resistor layer 3 are located.

[0096] As shown in Figures 25 and 26, the first protective layer 51 covers a portion of the main surface 11 of the substrate 1, the multiple heat-generating parts 31 of the resistor layer 3, and the wiring layer 4. The first protective layer 51 is electrically insulating. The composition of the first protective layer 51 includes silicon. The first protective layer 51 consists of, for example, silicon dioxide and silicon nitride. Alternatively, the first protective layer 51 may be a laminate composed of multiple types of these materials. The platen roller 79 ensures that the recording medium is superimposed on the region of the first protective layer 51 that covers the multiple heat-generating parts 31.

[0097] The second protective layer 52 covers the first protective layer 51, as shown in Figures 27 and 28. The second protective layer 52 is conductive. The second protective layer 52 is made of a material including, for example, C / SiC (a compacted mixture of carbon and silicon carbide). The recording medium is pressed against the second protective layer 52 by the platen roller 79 shown in Figures 25 and 26.

[0098] As shown in Figure 24, the wiring layer 4 includes a conductive member 44. As shown in Figure 27, the conductive member 44 is electrically connected to the connection portion 431 of the ground portion 43 and to the second protective layer 52. The conductive member 44 is in contact with the end face of the first protective layer 51. The conductive member 44 is made of a material including, for example, a resin containing silver particles.

[0099] As shown in Figure 25, the wiring layer 4 includes a protective member 45. The protective member 45 covers the conductive member 44. The protective member 45 has electrical insulating properties. The protective member 45 is made of a material including, for example, resin. Furthermore, the protective member 45 covers the extension 432 of the grounding portion 43 and a portion of each of the multiple individual wirings 42.

[0100] As shown in Figure 24, the multiple individual wires 42 are electrically connected to the multiple first wires 711 via the multiple first wires 74, the multiple drive elements 73, and the multiple second wires 75. The multiple first wires 711 are located on the main surface 11 of the substrate 1. The multiple first wires 711 are electrically connected to the connector 77.

[0101] Next, we will explain the effects and benefits of the A40 thermal printhead.

[0102] The first glaze layer 21 of the thermal print head A40 covers at least a portion of the substrate 1. The multiple heat-generating parts 31 of the resistor layer 3 are located on the opposite side of the substrate 1 from the first glaze layer 21 in the first direction z. The first glaze layer 21 contains a filler 211. The filler 211 has a hollow portion 211A. Therefore, with this configuration, the heat storage performance of the glaze layer is enhanced in the thermal print head A40, making it possible to suppress the increase in power consumption of the thermal print head A40. Furthermore, by having a configuration common to the thermal print head A10, the thermal print head A40 achieves the same effects as the thermal print head A10.

[0103] In the thermal print head A40, the second protective layer 52 is conductive. Furthermore, the wiring layer 4 includes a grounding portion 43 and a conductive member 44 that is electrically connected to the grounding portion 43 and the conductive member 44. By adopting this configuration, when the thermal print head A40 is used, the static electricity that has accumulated on the first protective layer 51 and the second protective layer 52 due to contact with the recording medium can be quickly discharged to the outside via the conductive member 44 and the grounding portion 43. Therefore, electrostatic discharge damage to the thermal print head A40 can be prevented.

[0104] This disclosure is not limited to the embodiments described above. The specific configuration of each part of this disclosure can be modified in various ways.

[0105] This disclosure includes embodiments described in the following appendix. [Note 1] circuit board and A first glaze layer covering at least a portion of the substrate, A resistor layer including a plurality of heat-generating parts located on the opposite side from the substrate with respect to the first glaze layer in a first direction, The wiring layer comprises a wiring layer that is electrically connected to the plurality of heat-generating sections and is arranged in contact with the resistor layer, The plurality of heating elements are arranged along a second direction perpendicular to the first direction, The first glaze layer contains a filler, The filler is a thermal print head having a hollow section. [Note 2] Viewed in the first direction, the plurality of heating elements overlap the filler, and the thermal print head is as described in Appendix 1. [Note 3] The filler has a shell portion surrounding the hollow portion, The aforementioned hollow section is a vacuum, as described in Appendix 2, for the thermal print head. [Note 4] The composition of the shell portion is a thermal print head as described in Appendix 3, containing silicon dioxide. [Note 5] The thermal print head according to any one of the appendices 2 to 4, wherein the particle size of the filler is 0.3 μm or more and 0.5 μm or less. [Note 6] The present invention further comprises a second glaze layer located on both sides of a third direction perpendicular to the first and second directions of the first glaze layer, A thermal print head according to any one of appendices 2 to 4, wherein the glass transition temperature of the first glaze layer is lower than the glass transition temperature of the second glaze layer. [Note 7] The second glaze layer has a base surface facing away from the side facing the substrate in the first direction, The base surface includes a pair of edges flanking the first glaze layer, The first glaze layer is in contact with the pair of edges, as described in Appendix 6, of the thermal print head. [Note 8] The thermal print head described in Appendix 7, wherein the first glaze layer is flush with the base surface. [Note 9] The first glaze layer is a thermal print head as described in Appendix 8, which protrudes from the base surface. [Note 10] In view in the second direction, the periphery of the portion of the first glaze layer protruding from the base surface forms a convex curve, as described in Appendix 9 of the thermal print head. [Note 11] The substrate has a main surface facing the side where the wiring layer is located in the first direction, and a protrusion projecting from the main surface. The aforementioned protrusion has a top surface, a first inclined surface, and a second inclined surface. The top surface is oriented in the first direction and is located away from the main surface. The first inclined surface and the second inclined surface are located between the main surface and the top surface and are inclined with respect to the main surface. The first and second inclined surfaces are located apart from each other in a third direction perpendicular to the first and second directions. The first glaze layer covers the top surface, and is a thermal print head as described in any of appendices 2 to 4. [Note 12] The thermal print head as described in Appendix 11, wherein the first inclined surface and the second inclined surface approach each other as they move from the main surface toward the top surface. [Note 13] The substrate is a thermal print head as described in Appendix 12, comprising a semiconductor material. [Note 14] The main surface, the first inclined surface, the second inclined surface, and the insulating layer covering the first glaze layer are further comprising The insulating layer is located between the substrate and the wiring layer, and is a thermal print head as described in Appendix 13. [Note 15] A thermal print head according to any one of appendices 2 to 4, further comprising a protective layer covering the plurality of heat-generating elements. [Note 16] The wiring layer includes common wiring and a plurality of individual wirings. The common wiring is electrically connected to the multiple heat-generating components. The thermal print head described in Appendix 15, wherein the plurality of individual wirings are individually electrically connected to the plurality of heat-generating parts. [Note 17] The heat dissipation member is located on the opposite side of the first glaze layer from the substrate in the first direction, The substrate is a thermal print head as described in Appendix 16, which is bonded to the heat dissipation member. [Explanation of Symbols]

[0106] A10, A20, A30, A40: Thermal printheads 1: Circuit board 11: Main surface 12: Back side 13: Convex part 130:Top surface 131:First slope 132:Second slope 21: First Glaze Layer 211: Filler 211A: Hollow part 211B: Shell part 22: Second Glaze Layer 22A:Aperture 221: Base 221A:Edge 23: Insulating layer 3: Resistor layer 31: Heat-generating part 4: Wiring layer 41: Common wiring 411: Base 412: Extension part 413: Detour section 42: Individual wiring 421: Base 422: Extension part 422A: Part 1 422B: Part 2 422C: Part 3 43: Grounding part 431: Connection part 432: Extension part 44: Conductive material 45: Protective component 5:Protective layer 5A: Wiring opening 51: 1st protective layer 52:Second protective layer 71: Wiring board 711: 1st wiring 712:Second wiring 72: Heat dissipation components 73: Driving element 74: First wire 75: Second wire 76: Sealing resin 77: Connector 79: Platen Roller z: 1st direction x: 2nd direction y: Third direction

Claims

1. circuit board and A first glaze layer covering at least a portion of the substrate, A resistor layer including a plurality of heat-generating parts located on the opposite side from the substrate with respect to the first glaze layer in a first direction, A wiring layer which is electrically connected to the plurality of heat-generating parts and is arranged in contact with the resistor layer, It comprises a second glaze layer, The plurality of heating elements are arranged along a second direction perpendicular to the first direction, The first glaze layer contains a filler, The filler has a hollow portion, The second glaze layer is located on both sides of the third direction, which is perpendicular to the first and second directions of the first glaze layer. A thermal printhead in which the glass transition temperature of the first glaze layer is lower than the glass transition temperature of the second glaze layer.

2. The thermal print head according to claim 1, wherein, viewed in the first direction, the plurality of heating elements overlap the filler.

3. The filler has a shell portion surrounding the hollow portion, The thermal print head according to claim 2, wherein the hollow portion is a vacuum.

4. The thermal print head according to claim 3, wherein the composition of the shell portion includes silicon dioxide.

5. The thermal print head according to any one of claims 2 to 4, wherein the particle size of the filler is 0.3 μm or more and 0.5 μm or less.

6. The second glaze layer has a base surface facing away from the side facing the substrate in the first direction, The base surface includes a pair of edges flanking the first glaze layer, The thermal print head according to any one of claims 1 to 5, wherein the first glaze layer is in contact with the pair of edges.

7. The thermal print head according to claim 6, wherein the first glaze layer is flush with the base surface.

8. The thermal print head according to claim 6, wherein the first glaze layer protrudes from the base surface.

9. The thermal print head according to claim 8, wherein, when viewed in the second direction, the periphery of the portion of the first glaze layer protruding from the base surface has a convex curve.

10. The thermal print head according to any one of claims 1 to 9, further comprising a protective layer covering the plurality of heat-generating parts.

11. The wiring layer includes common wiring and a plurality of individual wiring, The common wiring is electrically connected to the multiple heat-generating components. The thermal print head according to claim 10, wherein the plurality of individual wirings are individually electrically connected to the plurality of heat-generating parts.

12. Further comprising a heat dissipation member located on the opposite side from the first glaze layer with respect to the substrate in the first direction, The thermal print head according to claim 11, wherein the substrate is bonded to the heat dissipation member.

Images