Thermal printhead

Abstract

The present application provides a thermal head capable of alleviating heat concentration in the central portion of the heat generating portion, thereby improving printing efficiency. The thermal head (A1) includes a head substrate (1), a resistance layer (4) having a plurality of heat generating portions (41A) arranged in a main scanning direction (x), and a wiring layer (3) constituting a current path to the plurality of heat generating portions (41A). The wiring layer (3) includes: a first electrode portion (strip portion 321 or strip portion 313) connected to the plurality of heat generating portions (41A) respectively from one side (upstream side) of a sub-scanning direction (y), and a second electrode portion (each strip portion 331) connected to the plurality of heat generating portions (41A) respectively from the other side (downstream side) of the sub-scanning direction (y). The plurality of heat generating portions (41A) respectively include a sub-scanning central portion (421) and a pair of sub-scanning side portions (422A, 422B). The sub-scanning direction unit resistance value of the sub-scanning central portion (421) is smaller than each of the sub-scanning direction unit resistance values of the pair of sub-scanning side portions (422A, 422B).

Description

Technical Field

[0001] This invention relates to thermal printheads. Background Technology

[0002] Patent Document 1 discloses an example of a conventional thermal printhead. The thermal printhead described in this document includes: a support substrate, a resistive layer (heating resistive layer), and a wiring layer (electrode layer). The support substrate supports the resistive layer and the wiring layer. The resistive layer and the wiring layer are stacked on the support substrate. The resistive layer has multiple heating elements arranged along the main scanning direction. The wiring layer forms a power path for energizing the multiple heating elements. The wiring layer sandwiches the multiple heating elements opposite to each other in the sub-scanning direction. Each heating element, viewed in the thickness direction of the support substrate, forms, for example, a rectangular shape.

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2016-179554 Summary of the Invention

[0004] The problem that the invention aims to solve

[0005] In the thermal printhead described in Patent Document 1, the central portion of the heating element exhibits the highest temperature distribution. This is because the central portion of the heating element is relatively difficult to dissipate heat, and the heat is concentrated there. However, if the heat generated by the heating element exceeds a certain level, the print density on the printing medium becomes saturated, thus the excess heat leads to a decrease in printing efficiency.

[0006] The present invention was conceived in view of the above situation, and its purpose is to provide a thermal printhead that can alleviate heat concentration in the central part of the heating element, thereby improving printing efficiency.

[0007] Problem Solving Methods

[0008] A first aspect of the present invention provides a thermal printhead, characterized in that the thermal printhead comprises: a substrate; a resistive layer having a plurality of heating elements supported by the substrate and arranged in a main scanning direction; and a wiring layer supported by the substrate and forming a power path to the plurality of heating elements, the wiring layer comprising: a first electrode portion connected to one of the plurality of heating elements in a sub-scanning direction; and a second electrode portion connected to the plurality of heating elements in another sub-scanning direction, wherein the plurality of heating elements, viewed from the thickness direction of the substrate, comprises: a sub-scanning central portion located at the center in the sub-scanning direction; and a second electrode portion located in the sub-scanning direction. A pair of sub-scanning side portions are arranged to sandwich the sub-scanning central portion. One of the pair of sub-scanning side portions is connected to the first electrode portion, and the other is connected to the second electrode portion. The unit resistance value of the sub-scanning central portion in the sub-scanning direction is smaller than the unit resistance values ​​of each sub-scanning side portion in the sub-scanning direction. The unit resistance value of the sub-scanning central portion in the sub-scanning direction is the resistance value per unit length in the sub-scanning direction of the sub-scanning central portion. The unit resistance value of each sub-scanning side portion in the sub-scanning direction is the resistance value per unit length in the sub-scanning direction of each sub-scanning side portion in the pair of sub-scanning side portions.

[0009] A second aspect of the present invention provides a thermal printhead, characterized in that the thermal printhead comprises: a substrate; a resistive layer having a plurality of heating elements supported by the substrate and arranged in a main scanning direction; and a wiring layer supported by the substrate and forming a power path to the plurality of heating elements, the wiring layer comprising: a first electrode portion connected to one of the plurality of heating elements in a sub-scanning direction; and a second electrode portion connected to the plurality of heating elements in another of the sub-scanning directions, wherein the plurality of heating elements, viewed from the thickness direction of the substrate, comprises: a main scan central portion located at the center in the main scanning direction; and a pair of main scan sides arranged in the main scanning direction sandwiching the main scan central portion. The main scanning central portion and the pair of main scanning side portions are respectively connected to the first electrode portion and the second electrode portion. The unit resistance value of the main scanning central portion in the main scanning direction is larger than the unit resistance value of each of the main scanning directions of the pair of main scanning side portions. The unit resistance value of the main scanning central portion in the main scanning direction is the resistance value per contact length in the main scanning direction of the main scanning central portion and one of the first electrode portion or the second electrode portion. The unit resistance value of each of the main scanning side portions in the main scanning direction is the resistance value per contact length in the main scanning direction of the pair of main scanning side portions and one of the first electrode or the second electrode.

[0010] Invention Effects

[0011] According to the thermal printhead disclosed herein, heat concentration in the central part of the heating element can be reduced, thereby improving printing efficiency. Attached Figure Description

[0012] Figure 1 This is a plan view showing the thermal printhead in the first embodiment.

[0013] Figure 2 yes Figure 1 A magnified view of the main part of a portion of the floor plan shown.

[0014] Figure 3 yes Figure 2 Enlarged plan view of the main part of a section (Region III).

[0015] Figure 4 This is a partially enlarged cross-sectional view of a thermal printer including a thermal printhead equipped with the first embodiment, along... Figure 1 Cross-sectional view of line IV-IV.

[0016] Figure 5 yes Figure 4 The enlarged cross-sectional view of a portion of the cross-section shown is along... Figure 2 Cross-sectional view of the VV line.

[0017] Figure 6 yes Figure 5 Enlarged cross-sectional view of a major section.

[0018] Figure 7 This is a cross-sectional view of a major part of a process in the manufacturing method of the thermal printhead in the first embodiment.

[0019] Figure 8 This is a cross-sectional view of a major part of a process in the manufacturing method of the thermal printhead in the first embodiment.

[0020] Figure 9 This is a cross-sectional view of a major part of a process in the manufacturing method of the thermal printhead in the first embodiment.

[0021] Figure 10 This is a cross-sectional view of a major part of a process in the manufacturing method of the thermal printhead in the first embodiment.

[0022] Figure 11 This is a cross-sectional view of a major part of a process in the manufacturing method of the thermal printhead in the first embodiment.

[0023] Figure 12 This is a cross-sectional view of a major part of a process in the manufacturing method of the thermal printhead in the first embodiment.

[0024] Figure 13 This is a cross-sectional view of a major part of a process in the manufacturing method of the thermal printhead in the first embodiment.

[0025] Figure 14 This is a cross-sectional view of a major part of a process in the manufacturing method of the thermal printhead in the first embodiment.

[0026] Figure 15 This is an enlarged plan view showing the main part of the thermal printhead in the second embodiment.

[0027] Figure 16 This is an enlarged plan view showing the main part of the thermal printhead in the third embodiment.

[0028] Figure 17 This is an enlarged plan view showing the main part of the thermal printhead in the fourth embodiment.

[0029] Figure 18 It is along Figure 17 Enlarged cross-sectional view of the main part of the XVIII-XVIII line.

[0030] Figure 19 This is an enlarged plan view showing the main part of the thermal printhead in the fifth embodiment.

[0031] Figure 20 It is along Figure 19 Enlarged cross-sectional view of the main part of the XX-XX line.

[0032] Figure 21 This is an enlarged plan view of the main part of the heating element in the modified example.

[0033] Figure 22 This is an enlarged plan view of the main part of the heating element in the modified example.

[0034] Figure 23 This is an enlarged plan view of the main part of the heating element in the modified example.

[0035] Figure 24 This is an enlarged plan view of the main part of the heating element in the modified example.

[0036] Figure 25 This is an enlarged plan view of the main part of the heating element in the modified example.

[0037] Figure 26 This is an enlarged plan view of the main part of the heating element in the modified example.

[0038] Figure 27 This is an enlarged view showing the main part of the wiring layer in the modified example. Detailed Implementation

[0039] The preferred embodiment of the thermal printhead of the present invention will now be described with reference to the accompanying drawings. In the following description, the same or similar components are labeled with the same reference numerals, and repetitive descriptions are omitted.

[0040] Figures 1-6 This illustrates the thermal printhead in the first embodiment. The thermal printhead A1 includes: a substrate 1, an insulating layer 19, a protective layer 2, a wiring layer 3, a resistive layer 4, a connecting substrate 5, multiple bonding wires 61, multiple driver ICs 7, a protective resin 78, and a heat dissipation component 8. The thermal printhead A1 is assembled into a thermal printer Pr (see reference 1) to print on a printing medium (not shown). Figure 4 The thermal printer Pr includes a thermal printhead A1 and a pressure roller 91. The pressure roller 91 is directly opposite the thermal printhead A1. The printing medium is sandwiched between the thermal printhead A1 and the pressure roller 91 and is conveyed by the pressure roller 91 in the sub-scanning direction. Such printing media can be exemplified by thermal paper used to make barcode forms or receipts. According to the construction to be described in detail later, the thermal printhead A1 forms a plurality of heating elements 41A on the resistive layer 4, and selectively heats and drives the plurality of heating elements 41A to print the printing medium. Alternatively, a pressure roller 91 can be used instead of a pressure roll made of flat rubber. The pressure roll includes a portion of a cylindrical rubber having a large radius of curvature that is arc-shaped in cross-section. In this disclosure, the term "pressure roll" includes both the pressure roller 91 and the flat pressure roll.

[0041] Figure 1 This is a plan view representing the thermal printhead A1. Figure 2 This is a plan view showing the main parts of the thermal printhead A1. Figure 3 yes Figure 2 A partial enlarged view of a portion (Region III). Figure 4 This is a partially enlarged cross-sectional view of a thermal printer Pr equipped with an A1 thermal printhead, along... Figure 1 Cross-sectional view of line IV-IV. Figure 5 This is a cross-sectional view showing the main part of the thermal printhead A1, along... Figure 2 Cross-sectional view of the VV line. Figure 6 yes Figure 5 A magnified view of a portion of the image. Figures 1-3 In the original text, protective layer 2 was omitted. Figure 2 In the figures, multiple bonding lines 61 and protective resin 78 are omitted. In these figures, the thickness direction of the head substrate 1 is z, the main scanning direction is x, and the sub-scanning direction is y. The thickness direction z, the main scanning direction x, and the sub-scanning direction y are orthogonal to each other. Figures 1-3 In the diagram, the lower side of the sub-scanning direction y is the upstream side, and the upper side is the downstream side. Figures 4-6In the diagram, the right side of the sub-scanning direction y is the upstream side, and the left side is the downstream side.

[0042] The printhead substrate 1 supports the wiring layer 3 and the resistor layer 4. The printhead substrate 1 is a long and narrow rectangle with the main scanning direction x as its longitudinal direction. There is no particular limitation on the size of the printhead substrate 1. For example, the thickness (the dimension in the thickness direction z) is 725 μm, the dimension in the main scanning direction x is more than 50 mm and less than 150 mm, and the dimension in the secondary scanning direction y is more than 2.0 mm and less than 5.0 mm.

[0043] The printhead substrate 1 is made of a single-crystal semiconductor. This single-crystal semiconductor in the thermal printhead A1 is, for example, silicon (Si). The printhead substrate 1 may also be made of an insulating material (such as alumina or other ceramics) instead of a single-crystal semiconductor. Figures 4-6 As shown, the printhead substrate 1 has a first main surface 11 and a first back surface 12. The first main surface 11 and the first back surface 12 are separated in the thickness direction z and face opposite sides of each other in the thickness direction z. A wiring layer 3 and a resistive layer 4 are disposed on the first main surface 11.

[0044] like Figures 4-6 As shown, the printhead substrate 1 has a protrusion 13. The protrusion 13 protrudes from the first main surface 11 in the thickness direction z and extends in the main scanning direction x. In the illustrated example, the protrusion 13 is formed near the downstream of the sub-scanning direction y of the printhead substrate 1. Since the protrusion 13 is part of the printhead substrate 1, it is made of Si, which is a single-crystal semiconductor.

[0045] like Figure 6 As shown, the protrusion 13 has a top 130, a pair of first inclined portions 131A and 131B and a pair of second inclined portions 132A and 132B.

[0046] The top 130 is the portion of the protrusion 13 that is furthest from the first surface 11 along the thickness direction z. The top 130 is, for example, a surface that is approximately parallel to the first main surface 11. The top 130 is an elongated rectangle that extends along the main scanning direction x when viewed in the thickness direction z.

[0047] like Figure 6 As shown, a pair of first inclined portions 131A and 131B are connected to both sides of the top 130 in the sub-scanning direction y. The first inclined portion 131A is connected to the top 130 from the upstream side in the sub-scanning direction y. The first inclined portion 131B is connected to the top 130 from the downstream side in the sub-scanning direction y. Figure 6As shown, a pair of first inclined portions 131A and 131B are inclined at only an angle α1 relative to the first main surface 11 (inclined at the first inclination angle α1). The pair of first inclined portions 131A and 131B are planes of elongated rectangles extending in the main scanning direction x when viewed in the thickness direction z. In addition, the protrusion 13 may also be connected to the first inclined portions 131A and 131B, and has inclined portions adjacent to both ends of the top 130 in the main scanning direction x (not shown in the figure).

[0048] like Figure 6 As shown, a pair of second inclined portions 132A and 132B are connected to the first inclined portions 131A and 131B from the opposite side of the top 130 in the sub-scanning direction y. The second inclined portion 132A is sandwiched between the first inclined portion 131A and the first main surface 11 in the sub-scanning direction y. The second inclined portion 132A is connected to the first inclined portion 131A from the upstream side of the sub-scanning direction y and to the first main surface 11 from the downstream side of the sub-scanning direction y. The second inclined portion 132B is sandwiched between the first inclined portion 131B and the first main surface 11 in the sub-scanning direction y. The second inclined portion 132B is connected to the first inclined portion 131B from the downstream side of the sub-scanning direction y and to the first main surface 11 from the upstream side of the sub-scanning direction y. Figure 6 As shown, a pair of second inclined portions 132A and 132B are inclined at only an angle α2 relative to the first main surface 11 (inclined at a second inclination angle α2). Angle α2 is greater than angle α1. The pair of second inclined portions 132A and 132B are planes of elongated rectangles extending in the main scanning direction x when viewed in the thickness direction z. The pair of second inclined portions 132A and 132B are connected to the first main surface 11. In addition, the protrusion 13 may also be connected to the pair of second inclined portions 132A and 132B, and has inclined portions located at both ends of the main scanning direction x outside the main scanning direction x at the main scanning direction x ends of the top 130 (not shown).

[0049] In the printhead substrate 1, the first main surface 11 is a (100) surface. In the protrusion 13 formed using the manufacturing method described later, the angle α1 between each of the first inclined portions 131A, 131B and the first main surface 11 (refer to...) Figure 6 For example, 30.1 degrees, the angle α2 between each of the second inclined portions 132A, 132B and the first main surface 11 (see...) Figure 6 For example, it is 54.7 degrees. The z-dimensional dimension of the thickness direction of the protrusion 13 is, for example, more than 150 μm and less than 300 μm.

[0050] like Figure 5 and Figure 6As shown, the insulating layer 19 covers the first main surface 11 and the protrusion 13. The insulating layer 19 is used to further ensure the insulation of the first main surface 11 of the printhead substrate 1. As a constituent material of the insulating layer 19, SiO2 (TEOS-SiO2) formed by using TEOS (dicrystalline ester) as a raw material gas is used, for example. Other methods (such as thermal oxidation) to form SiO2 (oxide film) or SiN (nitride film) can also be used instead of TEOS-SiO2. The thickness of the insulating layer 19 is not particularly limited, for example, it is 5 μm or more and 15 μm or less (preferably 10 μm or more and 15 μm or less).

[0051] The wiring layer 3 forms a power path for energizing the multiple heating elements 41A. The wiring layer 3 is supported by the printhead substrate 1. Figure 5 and Figure 6 As shown, wiring layer 3 is stacked on resistive layer 4. The shape and configuration of wiring layer 3 are not limited to the example shown. Figure 1 and Figure 2 As shown, the wiring layer 3 has a general electrode 31, multiple independent electrodes 32 and multiple relay electrodes 33.

[0052] like Figure 2 and Figure 3 As shown, the plurality of relay electrodes 33 are strips comprising two strip-shaped portions 331 and a connecting portion 332, with the two strip-shaped portions 331 extending in the sub-scanning direction y. The two strip-shaped portions 331 are separated in the main scanning direction x in a generally parallel configuration. Each of the two strip-shaped portions 331 is connected to an adjacent heating portion 41A. Figure 2 and Figure 3 In the example shown, two strip-shaped portions 331 are connected to each heating element 41A from the downstream side of the sub-scanning direction y. The dimensions of the two strip-shaped portions 331 are approximately the same in the main scanning direction x. A connecting portion 332 connects to the ends of the two strip-shaped portions 331 and to the ends on the opposite side in the sub-scanning direction y. The connecting portion 332 is a strip-shaped portion extending in the main scanning direction x. A plurality of relay electrodes 33 each have a semi-U-shaped opening facing the upstream side of the sub-scanning direction y and are arranged at equal intervals in the main scanning direction x. The plurality of relay electrodes 33 are located downstream of the plurality of heating elements 41A in the sub-scanning direction y.

[0053] like Figure 2As shown, the general-purpose electrode 31 includes multiple through-holes 311, multiple branch sections 312, multiple strip-shaped sections 313, and connecting sections 314. The multiple through-holes 311 are strip-shaped sections extending in the sub-scanning direction y. The multiple through-holes 311 are arranged at equal intervals in the main scanning direction x. A branch section 312 and two strip-shaped sections 313 are provided at the top end side (downstream side of the sub-scanning direction y) of each of the multiple through-holes 311. These two strip-shaped sections 313 are respectively connected to adjacent heating sections 41A. Figure 2 and Figure 3 In the example shown, the two strip-shaped portions 313 are connected to the heating element 41A from the upstream side of the sub-scanning direction y. The size of the main scanning direction x of each strip-shaped portion 313 is approximately the same as the size of the main scanning direction x of each strip-shaped portion 331. Furthermore, the strip-shaped portions 313 overlap with the strip-shaped portions 331 when viewed from the sub-scanning direction y. Multiple branch portions 312 are connected to the top end of each through-hole 311. Each branch portion 312 is connected to a through-hole 311 at the opposite end of each end connected to the two strip-shaped portions 313 along the sub-scanning direction y. The two strip-shaped portions 313 are connected to the heating element 41A from the upstream side of the sub-scanning direction y. A connecting portion 314 is located at the base end side (upstream side of the sub-scanning direction y) of the multiple through-holes 311 and extends along the main scanning direction x. The multiple through-holes 311 are connected to the connecting portion 314. The connecting part 314 is connected to the connector 59 via the bonding line 61 and the wiring of the connecting substrate 5, and a driving voltage is applied.

[0054] The polarities of the individual electrodes 32 are opposite to those of the common electrode 31. For example... Figure 2 As shown, multiple individual electrodes 32 are arranged separately in the main scanning direction x. Figure 2 As shown, each of the multiple individual electrodes 32 includes a strip-shaped portion 321 and a junction portion 322. In each individual electrode 32, the strip-shaped portion 321 is a strip extending in the sub-scanning direction y, located upstream of the heating portion 41A in the sub-scanning direction y. Figure 3 In the example shown, the strip portion 321 is connected to the heating portion 41A at its top side (downstream of the sub-scanning direction y). The dimension of the strip portion 321 in the main scan direction x is approximately the same as the dimension of each strip portion 331 in the main scan direction x. Furthermore, the downstream end of the strip portion 321 in the sub-scanning direction y overlaps with the strip portion 331 when viewed in the sub-scanning direction y. In each individual electrode 32, a bonding portion 322 is provided at the upstream end of the strip portion 321 in the sub-scanning direction y. The bonding portion 322 is connected to one of the output pads 72 (described later) of the plurality of driver ICs 7 via a bonding line 61.

[0055] like Figure 2As shown, in the thermal printhead A1, the through portions 311 of the common electrode 31 are sandwiched between the strip portions 321 of two individual electrodes 32. One of the two strip portions 331 of each relay electrode 33 is connected to a heating element 41A connected to the common electrode 31, and the other of the two strip portions 331 of the relay electrode 33 is connected to one of the individual electrodes 32. Therefore, when each individual electrode 32 is energized, current flows through the heating element 41A connected to it, and through the heating element 41A connected to it via the relay electrode 33, causing these heating elements 41A to heat up. That is, both heating elements 41A heat up simultaneously. In the thermal printhead A1, when each heating element 41A is energized, current flows through each heating element 41A along the sub-scanning direction y.

[0056] like Figure 5 and Figure 6 As shown, the wiring layer 3 (each common electrode 31, a plurality of individual electrodes 32 and a plurality of relay electrodes 33) includes a first conductor layer 301 and a second conductor layer 302 stacked in the thickness direction z.

[0057] like Figure 5 and Figure 6 As shown, a first conductor layer 301 is formed on a resistive layer 4. The resistance per unit length of the first conductor layer 301 in the sub-scanning direction y is lower than that of the resistive layer 4, and it is made of a resistive material with higher resistance than that of the second conductor layer 302. The conductivity of the first conductor layer 301 is preferably, for example, 10. -6 ~10 -7 The thermal conductivity of the first conductor layer 301 is preferably less than 100 W / m. For example, Ti (titanium) is used as the constituent material of the first conductor layer 301, but Ta, Ga, Sn, PtIr, Pt, Ti (thallium), V (vanadium), or Cr can be used instead of Ti. The method of forming the first conductor layer 301 is not particularly limited; it can be formed by sputtering, CVD, electroplating, etc., and is appropriately selected according to the constituent material used. For example, when the constituent material of the first conductor layer 301 is Ti, the first conductor layer 301 is formed by sputtering. The thickness of the first conductor layer 301 is not particularly limited; for example, its thickness is 0.1 μm or more and 0.2 μm or less.

[0058] like Figure 5 and Figure 6As shown, a second conductor layer 302 is formed on a first conductor layer 301. The second conductor layer 302 partially covers the first conductor layer 301. Thus, the first conductor layer 301 has a portion exposed from the second conductor layer 302. The second conductor layer 302 is made of a resistive material with a lower resistivity per unit length in the sub-scanning direction y than the resistive layer 4 and the first conductor layer 301. The resistivity of the second conductor layer 302 is preferably, for example, 10. -7 The thermal conductivity is less than Ωm. Furthermore, the second conductor layer 302 is made of a material with a higher thermal conductivity than the first conductor layer 301. The thermal conductivity of the second conductor layer 302 is preferably 100 W / m or higher. The constituent material of the second conductor layer 302 is, for example, Cu, but Cu alloys, Al, Al alloys, Au, Ag, Ni, or W (tungsten) can also be used instead of Cu. The method of forming the second conductor layer 302 is not particularly limited; it can be formed by sputtering, CVD, electroplating, etc., depending on the constituent material used. For example, when the constituent material of the second conductor layer 302 is Cu, it is formed by sputtering. Furthermore, when the constituent material of the second conductor layer 302 is Au, Ag, or Ni, it is generally formed by electroplating, but in this case, the second conductor layer 302 may also include a seed layer (e.g., Cu (copper)). The second conductor layer 302 is thicker than the first conductor layer 301. The thickness of the second conductor layer 302 depends on the material used, the current flowing through the wiring layer 3, etc. For example, the thickness of the second conductor layer 302 is more than 0.5 μm and less than 5 μm.

[0059] like Figure 3 As shown, in the thermal printhead A1, the portions of each strip 313 (common electrode 31), each strip 321 (individual electrode 32), and each strip 331 (relay electrode 33) that connect to each heating element 41A are composed of a first conductor layer 301 exposed from the second conductor layer 302. That is, each strip 313 (common electrode 31), each strip 321 (individual electrode 32), and each strip 331 (relay electrode 33) includes portions composed solely of the first conductor layer 301, and portions where the first conductor layer 301 and the second conductor layer 302 are stacked. Unlike this configuration, the portion connecting to each heating element 41A may also be a configuration where the second conductor layer 302 is stacked on top of the first conductor layer 301. That is, each strip 313 (common electrode 31), each strip 321 (individual electrode 32), and each strip 331 (relay electrode 33) are respectively stacked with a first conductor layer 301 and a second conductor layer 302 in the entire forming range.

[0060] like Figure 5 and Figure 6As shown, the resistive layer 4 is supported by the printhead substrate 1 and is also supported by the printhead substrate 1 through an insulating layer 19. The resistive layer 4 has a plurality of heating elements 41A. By selectively energizing the plurality of heating elements 41A, the printing medium is locally heated. Each heating element 41A is a region exposed from the wiring layer 3 in the resistive layer 4. The plurality of heating elements 41A are arranged along the main scanning direction x and are separated from each other in the main scanning direction x. The resistive layer 4 is made of a resistive material whose resistance per unit length in the sub-scanning direction y is higher than that of the wiring layer 3. The resistivity of the resistive layer 4 is preferably 10. -6 The resistivity layer 4 has a thickness of Ωm or more. For example, TaN is used as the constituent material of the resistivity layer 4, but TaN can also be replaced by TaSiO2, TiON, PolySi, Ta2O5, RuO2, RuTiO, or TaSiN. The method of forming the resistivity layer 4 is not particularly limited; it can be formed by sputtering, CVD, electroplating, etc., depending on the constituent material used. For example, when the constituent material of the resistivity layer 4 is TaN, the resistivity layer 4 is formed by sputtering. The thickness of the resistivity layer 4 is constant; for example, this thickness is 0.02 μm or more and 0.1 μm or less (preferably around 0.08 μm).

[0061] Each heating element 41A is disposed on the protrusion 13. Figure 6 In the example shown, each heating element 41A is formed across the top 130 from the first inclined portion 131B. The upstream end of each heating element 41A in the sub-scanning direction y is located on the top 130, and the downstream end of each heating element 41A in the sub-scanning direction y is located on the first inclined portion 131B. It is not limited to any heating element 41A being disposed on the protrusion 13. Figure 6 The location shown.

[0062] like Figure 3 As shown, each heating element 41A includes a sub-scanning central part 421 and a pair of sub-scanning side parts 422A and 422B.

[0063] The sub-scanning central portion 421 is located at the center of the sub-scanning direction y when viewed in the thickness direction z. A pair of sub-scanning side portions 422A and 422B are arranged sandwiching the sub-scanning central portion 421 when viewed in the thickness direction z. The sub-scanning side portion 422A is located upstream of the sub-scanning central portion 421 in the sub-scanning direction y. The upstream end of the sub-scanning side portion 422A in the sub-scanning direction y is connected to one of the strip portion 313 (common electrode 31) or the strip portion 321 (individual electrode 32), and the downstream end in the sub-scanning direction y is connected to the sub-scanning central portion 421. The sub-scanning side portion 422B is located downstream of the sub-scanning central portion 421 in the sub-scanning direction y. The upstream end of the sub-scanning side portion 422B in the sub-scanning direction y is connected to the sub-scanning central portion 421, and the downstream end in the sub-scanning direction y is connected to each strip portion 331 (relay electrode 33). The boundaries of the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A and 422B are as follows: Figure 3 The image shows a straight line that is roughly parallel to the main scanning direction x.

[0064] In each heating element 41A, as described above, current flows along the sub-scanning direction y. Therefore, the sub-scanning central portion 421 and a pair of sub-scanning side portions 422A, 422B are arranged along the direction of the current flowing through each heating element 41A. That is, the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A, 422B are connected in series between the strip portion 321 and the strip portion 331, or between the strip portion 313 and the strip portion 331. Therefore, the current values ​​flowing through the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A, 422B are approximately the same, and the portions with higher resistance values ​​in the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A, 422B generate more heat.

[0065] In each heating element 41A, the unit resistance value R11 of the sub-scanning central part 421 in the sub-scanning direction is smaller than the unit resistance value R12 of each of the sub-scanning side parts 422A and 422B in the sub-scanning direction. The unit resistance value R11 of the sub-scanning central part 421 in the sub-scanning direction y is the resistance value per unit length in the sub-scanning direction y of the sub-scanning central part 421, and is calculated by dividing the resistance value of the entire sub-scanning central part 421 by the size of the sub-scanning central part 421 in the sub-scanning direction y. The unit resistance value R12 of the sub-scanning side part 422A in the sub-scanning direction y is the resistance value per unit length in the sub-scanning direction y of the sub-scanning side part 422A, and is calculated by dividing the resistance value of the entire sub-scanning side part 422A by the size of the sub-scanning side part 422A in the sub-scanning direction y. The unit resistance value R12 of the sub-scanning side portion 422B in the sub-scanning direction is the resistance value per unit length in the sub-scanning direction y of the sub-scanning side portion 422B, and is calculated by dividing the resistance value of the entire sub-scanning side portion 422B by the size of the sub-scanning direction y of the sub-scanning side portion 422B.

[0066] exist Figure 3 In the example shown, a portion of the sub-scanning central portion 421 of each heating element 41A protrudes further to both sides of the main scanning direction x than the pair of sub-scanning side portions 422A and 422B. Therefore, the dimension along the main scanning direction x of the sub-scanning central portion 421 is larger than the dimensions along the main scanning direction x of the pair of sub-scanning side portions 422A and 422B. Consequently, since the resistive layer 4 has the same thickness, the cross-section orthogonal to the sub-scanning direction y of the sub-scanning central portion 421 is larger than the cross-sections orthogonal to the sub-scanning direction y of the pair of sub-scanning side portions 422A and 422B. Since the resistance value is inversely proportional to the cross-sectional area of ​​the conductor, the resistance value of the sub-scanning central portion 421 is smaller than the resistance values ​​of the pair of sub-scanning side portions 422A and 422B. Therefore, the unit resistance value R11 of the sub-scanning central portion 421 in the sub-scanning direction is smaller than the unit resistance value R12 of the pair of sub-scanning side portions 422A and 422B in the sub-scanning direction.

[0067] like Figure 3 As shown, each heating element 41A includes a main scanning central part 431 and a pair of main scanning side parts 432A and 432B.

[0068] The main scanning central portion 431 is located at the center of the sub-scanning direction y when viewed in the thickness direction z. A pair of main scanning side portions 432A and 432B are arranged sandwiching the main scanning central portion 431 when viewed in the thickness direction z. The main scanning side portion 432A is located on one side of the main scanning direction x relative to the main scanning central portion 431 and is connected to the main scanning central portion 431 from this side of the main scanning direction x. The main scanning side portion 432B is located on the other side of the main scanning direction x relative to the main scanning central portion 431 and is connected to the main scanning central portion 431 from this other side of the main scanning direction x. The upstream end of the main scanning central portion 431 and the pair of main scanning side portions 432A and 432B in the sub-scanning direction y is connected to one of the strip portion 313 (common electrode 31) or the strip portion 321 (individual electrode 32), and the downstream end in the sub-scanning direction y is connected to the strip portion 331 (individual electrode 32). Figure 3 As shown, the boundaries of the main scanning center portion 431 and the main scanning side portions 432A and 432B are straight lines that are generally parallel to the sub-scanning direction y.

[0069] As described above, in each heating element 41A, current flows along the sub-scanning direction y. Therefore, the main scanning central portion 431 and a pair of main scanning side portions 432A, 432B are arranged in a direction orthogonal to the direction of the current flowing through each heating element 41A. That is, the main scanning central portion 431 and the pair of main scanning side portions 432A, 432B are connected in series between the strip portion 321 and the strip portion 331, or between the strip portion 313 and the strip portion 331. Therefore, the voltage values ​​applied to the main scanning central portion 431 and the pair of main scanning side portions 432A, 432B are approximately the same, and the portions with lower resistance values ​​in the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A, 422B generate more heat.

[0070] In each heating element 41A, the unit resistance value R21 of the main scanning central part 431 in the main scanning direction is larger than the unit resistance value R22 of each of the main scanning side parts 432A and 432B in the main scanning direction. The unit resistance value R21 of the main scanning central part 431 in the main scanning direction is the resistance value of the main scanning central part 431 and the strip part 331 per contact length in the main scanning direction x, which is calculated by dividing the resistance value of the entire main scanning central part 431 by the boundary L21 along the boundary between the main scanning central part 431 and the strip part 331 (see reference). Figure 3 The resistance value R21 of the main scanning center portion 431 in the main scanning direction is calculated from the dimension of the main scanning direction x. The unit resistance value R21 of the main scanning center portion 431 in the main scanning direction x can also be the resistance value of the main scanning center portion 431 and the strip portion 313 (or strip portion 321) at each contact length in the main scanning direction x. In this case, it is calculated by dividing the resistance value of the entire main scanning center portion 431 by the boundary L11 along the main scanning center portion 431 and the strip portion 313 (or strip portion 321) (see reference). Figure 3 The resistance value R22 of the main scanning side portion 432A in the main scanning direction x is calculated by dividing the resistance value of the main scanning side portion 432A and the strip portion 331 by the boundary L221 between the main scanning side portion 432A and the strip portion 331 in the main scanning direction x. Figure 3 The resistance value R22 of the main scanning side portion 432A in the main scanning direction is calculated from the dimension of the main scanning direction x. The unit resistance value R22 of the main scanning side portion 432A in the main scanning direction can also be the resistance value of the main scanning side portion 432A and the strip portion 313 (or strip portion 321) at each contact length in the main scanning direction x. In this case, it is calculated by dividing the resistance value of the entire main scanning side portion 432A by the boundary L121 along the main scanning center portion 431 and the strip portion 313 (or strip portion 321) (see reference). Figure 3The resistance value R22 of the main scanning side portion 432B in the main scanning direction x is calculated by dividing the resistance value of the main scanning side portion 432B and the strip portion 331 by the resistance value of each contact length in the main scanning direction x. This is achieved by dividing the resistance value of the entire main scanning side portion 432B by the boundary L222 along the main scanning side portion 432B and the strip portion 331 (see reference). Figure 3 The resistance value R22 of the main scanning side portion 432B in the main scanning direction is calculated from the dimension of the main scanning direction x. The unit resistance value R22 of the main scanning side portion 432B in the main scanning direction x can also be the resistance value of the main scanning side portion 432B and the strip portion 313 (or strip portion 321) per contact length in the main scanning direction x. In this case, it is calculated by dividing the resistance value of the entire main scanning side portion 432B by the boundary L122 along the main scanning center portion 431 and the strip portion 313 (or strip portion 321) (see reference). Figure 3 The size of the main scanning direction x is calculated from the main scanning direction x.

[0071] exist Figure 3 In the example shown, each of the pair of main scanning side portions 432A and 432B has a portion whose dimension along the main scanning direction x is larger than the dimension along the main scanning direction x along the boundaries L221 and L222 of the strip portion 331. Furthermore, the main scanning center portion 431 does not have a portion whose dimension along the main scanning direction x is larger than the dimension along the main scanning direction x along the boundary L21 of the strip portion 331. Since both the pair of main scanning side portions 432A and 432B have such portions, the unit resistance value R22 of each of the pair of main scanning side portions 432A and 432B in the main scanning direction is smaller than the unit resistance value R21 of the main scanning center portion 431 in the main scanning direction. That is, the unit resistance value R21 of the main scanning center portion 431 in the main scanning direction is greater than the unit resistance value R22 of each of the pair of main scanning side portions 432A and 432B in the main scanning direction.

[0072] exist Figure 3 In the example shown, the size of the sub-scanning direction y along the central portion 431 of the main scan is approximately the same as the size of the sub-scanning direction y along the pair of main scan side portions 432A, 432B.

[0073] like Figure 5 and Figure 6 As shown, protective layer 2 covers and protects wiring layer 3 and resistive layer 4. Protective layer 2 is made of an insulating material. For example, SiN (silicon nitride) is used as this insulating material, but SiO2 (silicon oxide), SiC (silicon carbide), AlN (aluminum nitride), etc., can also be used instead of SiN. Protective layer 2 can be composed of a single layer or multiple layers of the aforementioned insulating material. The thickness of protective layer 2 is not particularly limited; for example, the thickness of protective layer 2 is 1.0 μm to 10 μm.

[0074] like Figure 5 As shown, the protective layer 2 has multiple gasket openings 21. Each gasket opening 21 penetrates the protective layer 2 in the thickness direction z. The multiple gasket openings 21 expose the junction 322 of each individual electrode 32. Unlike the illustrated example, conductive material may also be filled into the multiple gasket openings 21. In this case, an electroplated layer can be formed on the conductive material. The structure of this electroplated layer is not particularly limited; for example, Ni, Pd (palladium), and Au may be sequentially stacked from the surface of the conductive material.

[0075] like Figure 1 , Figure 2 and Figure 4 As shown, the connection substrate 5 is positioned upstream of the printhead substrate 1 in the sub-scanning direction y. The connection substrate 5 is, for example, a PCB substrate, and houses various driver ICs 7 and connectors 59 (described later). The shape of the connection substrate 5 is not particularly limited; in this embodiment, it is a rectangular shape with the main scanning direction x as its longitudinal direction. The connection substrate 5 is as follows... Figure 4 The diagram shows a second main surface 51 and a second back surface 52. The second main surface 51 faces the same side as the first main surface 11 of the printhead substrate 1, and the second back surface 52 faces the same side as the first back surface 12 of the printhead substrate 1. In this embodiment, the second main surface 51 is located below the first main surface 11 in the thickness direction z-graph.

[0076] like Figure 2 As shown, a plurality of control electrodes 55 are formed on the connection substrate 5. Each control electrode 55 is disposed on the second main surface 51 and is disposed upstream of the sub-scanning direction y compared to the driver IC7. Each control electrode 55 extends along the sub-scanning direction y. Each control electrode 55 is connected to one of the input pads 71 ​​(described later) of the driver IC7 via a bonding line 61, and is connected to a connector 59 via wiring on the connection substrate 5.

[0077] To selectively drive multiple heating elements 41A, multiple driver ICs 7 are used to allow current to flow individually through each heating element 41A. The number of driver ICs 7 is appropriately varied depending on the number of heating elements 41A. The power-on control of each driver IC 7 is performed via connector 59, wiring on the connection substrate 5, and control electrodes 55, based on command signals input from the thermal printhead A1. Each driver IC 7 is mounted on the second main surface 51 of the connection substrate 5 and is connected to multiple individual motors 32 and multiple control electrodes 55 via multiple bonding wires 61.

[0078] like Figure 2As shown, multiple input pads 71 ​​and multiple output pads 72 are disposed on each driver IC 7. The multiple input pads 71 ​​are terminals for inputting various main signals, etc., used to control each driver IC 7. The multiple input pads 71 ​​are disposed near the upstream end of each driver IC 7 in the sub-scanning direction y. Each input pad 71 is connected to each control electrode 55 via a bonding line 61. The multiple output pads 72 are terminals through which current flows to drive the heating element 41A. The multiple output pads 72 are disposed near the downstream end of each driver IC 7 in the sub-scanning direction y. Each output pad 72 is connected to the bonding portion 322 of each individual electrode 32 via a bonding line 61.

[0079] Protective resin 78 covers multiple driver ICs 7 and multiple bonding wires 61. The protective resin 78 is made of, for example, an insulating resin, and is, for example, black. Figure 1 and Figure 4 As shown, the protective resin 78 is formed in a manner that spans across the printhead substrate 1 and the connecting substrate 5.

[0080] Connector 59 is used to connect the thermal printhead A1 to the thermal printer Pr. Connector 59 is mounted on the connection substrate 5 and is connected to the input pad 71 of the driver IC7 via the wiring pattern of the connection substrate 5 (not shown) and the control electrode 55.

[0081] The heat dissipation component 8 supports the printhead substrate 1 and the connecting substrate 5, and is used to dissipate a portion of the heat generated by the multiple heat-generating parts 41A to the outside via the printhead substrate 1. The heat dissipation component 8 is, for example, a block-shaped component made of a metal such as Al (aluminum). Figure 4 As shown, the heat dissipation component 8 has a first support surface 81 and a second support surface 82. The first support surface 81 and the second support surface 82 both face upwards in the thickness direction z. The first support surface 81 is located downstream in the sub-thickness direction y compared to the second support surface 82. Figure 4 As shown, the first back surface 12 of the printhead substrate 1 is joined to the first support surface 81, and the second back surface 52 of the connecting substrate 5 is joined to the second support surface 82.

[0082] Next, the manufacturing method of the thermal printhead A1 will be explained. Figures 7-14 It is a cross-sectional view representing one step of the manufacturing method.

[0083] First, such as Figure 7As shown, a substrate material 1K is prepared. The substrate material 1K is made of a single-crystal semiconductor, such as a portion of a generally circular silicon (Si) wafer. A silicon wafer contains multiple substrate materials 1K. In the following figures, a portion of the silicon wafer and a substrate material 1K (printer substrate 1) corresponding to a thermal printhead A1 is sometimes illustrated. The thickness of the substrate material 1K (in other words, the thickness of the silicon wafer) is not particularly limited, but in this embodiment, it is, for example, about 725 μm. The substrate material 1K has a first main surface 11K and a first back surface 12K facing opposite sides to each other. The first main surface 11K is a (100) surface.

[0084] Next, after covering the first master surface 11K with a prescribed mask layer, anisotropic etching is performed, for example, using KOH (potassium hydroxide). For the reagent used in this anisotropic etching, TMAH (tetramethylammonium hydroxide) can also be used instead of KOH, but the processing speed (etching rate) is faster when using KOH. Through this anisotropic etching, such as... Figure 8 As shown, a protrusion 13K is formed on substrate material 1K. The protrusion 13K protrudes from the first main surface 11K and extends in the main scanning direction x. The protrusion 13K has a top 130K and a pair of inclined portions 132K. The top 130K is a surface parallel to the first main surface 11K and is the same (100) surface as the first main surface 11K. The pair of inclined portions 132K are located on both sides of the top 130K in the sub-scanning direction y, between the top 130K and the first main surface 11K. The pair of inclined portions 132K are planes inclined toward the top 130K and the first main surface 11K, respectively. The angle formed by the pair of inclined portions 132K with the first main surface 11K and the top 130K is 54.7 degrees.

[0085] Then, after removing the aforementioned mask layer, anisotropic etching is performed, for example, using TMAH. The reagent used in this anisotropic etching can be KOH instead of TMAH; however, when using TMAH, the surfaces formed by etching (e.g., the pair of first inclined portions 131A, 131B described later) become smooth surfaces. Through this anisotropic etching, such as... Figure 9 As shown, substrate material 1K forms a printhead substrate 1 having a first main surface 11, a first back surface 12, and a protrusion 13. The protrusion 13 has a top 130, a pair of first inclined portions 131A and 131B, and a pair of second inclined portions 132A and 132B. The top 130 is a portion of the top 130K, and the pair of second inclined portions 132A and 132B are portions of the pair of inclined portions 132K. The pair of first inclined portions 131A and 131B are the portions where the boundary between the top 130K and the pair of inclined portions 132K is etched using TMAH. The angle α1 between each of the first inclined portions 131A and 131B and the first main surface 11 (refer to...) Figure 9The angle α2 between each of the second inclined portions 132A and 132B and the first main surface 11 is 30.1 degrees (refer to...). Figure 9 The temperature is 54.7 degrees.

[0086] Next, as Figure 10 As shown, an insulating layer 19 is formed. For example, the insulating layer 19 is formed by depositing SiO2, which is formed using TEOS (tetraethyl o-silicate) as a raw material gas, on the printhead substrate 1 using a CVD method. The method for forming the insulating layer 19 is not limited to this.

[0087] Next, as Figure 11 As shown, a resistive film 4K is formed. In the process of forming the resistive film 4K (resistive film formation process), a thin film of TaN is formed, for example, by sputtering on the insulating layer 19. The method of forming the resistive film 4K is not limited to this.

[0088] Then, as Figure 12 and Figure 13 As shown, a wiring film 3K is formed. In the process of forming the wiring film 3K (wiring film forming process), there are... Figure 12 The formation of the first conductor film 301K and shown Figure 13 The diagram shows two steps for forming the second conductive film 302K. In the step of forming the first conductive film 301K (the first film formation step), for example, a thin film of Ti is formed on the resistive film 4K by sputtering. At this time, as... Figure 12 As shown, the first conductive film 301K substantially covers the entire resistive film 4K. In the process of forming the second conductive film 302K (the second film formation process), for example, a layer made of Cu is formed on the first conductive film 301K by electroplating or sputtering. At this time, as... Figure 13 As shown, the second conductor film 302K roughly covers the entire first conductor film 301K.

[0089] Next, as Figure 14 As shown, partial removal of the second conductor film 302K, partial removal of the first conductor film 301K, and partial removal of the resistive film 4K are performed sequentially. For example, the process of partially removing the first conductor film 301K (first partial removal process), the process of partially removing the second conductor film 302K (second partial removal process), and the process of partially removing the resistive film 4K (resistive film partial removal process) are performed by etching. The first conductor layer 301 is formed by the first partial removal process, the second conductor layer 302 is formed by the second partial removal process, and the resistive layer 4 is formed by the resistive film partial removal process. Furthermore, the resistive film partial removal process can also be performed in the first film formation process (see reference). Figure 12 ) and the second film-forming process (refer to Figure 13The first conductor layer 301 and the second conductor layer 302 formed constitute a wiring layer 3 having a common electrode 31, a plurality of individual electrodes 32 and a plurality of relay electrodes 33. In addition, the resistive layer 4 formed has a plurality of heating elements 41A.

[0090] Next, a protective layer 2 is formed. For example, the protective layer 2 is formed by depositing SiN on the insulating layer 19, the wiring layer 3 (the first conductor layer 301 and the second conductor layer 302), and the resistive layer 4 using CVD. Furthermore, the protective layer 2 is partially removed by etching or the like, thereby forming a pad opening 21. Afterward, a silicon wafer is divided into multiple printhead substrates 1 using a dicing device or the like.

[0091] Then, an assembly process is performed on a printhead substrate 1. The thermal printhead A1 is manufactured by mounting the printhead substrate 1 and the connecting substrate 5 on the heat dissipation component 8, mounting the driver IC 7 on the connecting substrate 5, joining multiple bonding wires 61, and forming a protective resin 78.

[0092] The function and effect of the thermal printhead A1 are described below.

[0093] The thermal printhead A1 includes a resistive layer 4 having multiple heating elements 41A. Viewed in the thickness direction (thickness direction z) of the printhead substrate 1, each heating element 41A includes a sub-scanning central portion 421 located at the center in the sub-scanning direction y, and a pair of sub-scanning side portions 422A and 422B arranged sandwiching the sub-scanning central portion 421 in the sub-scanning direction y. Of the pair of sub-scanning side portions 422A and 422B, sub-scanning side portion 422A is connected to a first electrode portion, and sub-scanning side portion 422B is connected to a second electrode portion. In this embodiment, the first electrode portion is each strip portion 321 (each individual electrode 32) or each strip portion 313 (common electrode 31), and the second electrode portion is each strip portion 331 (each relay electrode 33). The unit resistance value R11 of the sub-scanning central portion 421 in the sub-scanning direction is smaller than the unit resistance value R12 of each of the pair of sub-scanning side portions 422A and 422B in the sub-scanning direction. In each heating portion 41A, the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A and 422B are connected in series between the first electrode portion and the second electrode portion. Therefore, since the current flowing through the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A and 422B is approximately the same, heating can be suppressed in the sub-scanning central portion 421, where the unit resistance value in the sub-scanning direction is smaller than that of each of the sub-scanning side portions 422A and 422B. That is, heating in the central portion of each heating portion 41A in the sub-scanning direction y can be suppressed. Therefore, the thermal printhead A1 can alleviate heat concentration in the central portion of each heating portion 41A, thus preventing excessive heating in the central portion of each heating portion 41A and improving printing efficiency.

[0094] In the thermal printhead A1, the sub-scanning central portion 421 protrudes to both sides of the main scanning direction x, compared to the pair of sub-scanning side portions 422A and 422B. With this configuration, the dimension along the main scanning direction x of the sub-scanning central portion 421 can be larger than the respective dimensions along the main scanning direction x of the pair of sub-scanning side portions 422A and 422B. Furthermore, this protruding portion is formed, for example, in a heating element that was previously considered to be rectangular in shape (see reference). Figure 3The area where the wiring layer 3 and the resistive layer 4 are not formed (the two dashed lines) is in the heating element. That is, in the past heating element, a portion of the resistive layer 4 was placed in an insulated area, so the formation area of ​​each main scanning side portion 432A, 432B of the heating element 41A is larger than that of the past heating element. In this way, the current flowing through each main scanning side portion 432A, 432B increases. As described above, the main scanning central portion 431 and the pair of main scanning side portions 432A, 432B are connected in parallel between the first electrode portion and the second electrode portion. Therefore, by increasing the current flowing through each main scanning side portion 432A, 432B, the current flowing through the main scanning central portion 431 can be reduced. That is, the heating of each heating element 41A in the main scanning central portion 431 can be suppressed. The thermal printhead A1 can alleviate the heat concentration in the central portion of the main scanning direction x of each heating element 41A, thus improving printing efficiency.

[0095] In the thermal printhead A1, multiple heating elements 41A include a main scanning central part 431 located in the center of the main scanning direction x, and a pair of main scanning side parts 432A and 432B arranged sandwiching the main scanning central part 431 in the main scanning direction x. The upstream end of the main scanning central part 431 and the pair of main scanning side parts 432A and 432B in the sub-scanning direction y is connected to a first electrode part, and the downstream end of the sub-scanning direction y is connected to a second electrode part. In this embodiment, the first electrode part is each strip 321 (each individual electrode 32) or each strip 313 (common electrode 31), and the second electrode part is each strip 331 (each relay electrode 33). The unit resistance value R21 of the main scanning central part 431 in the main scanning direction is larger than the unit resistance value R22 of each of the pair of main scanning side parts 432A and 432B in the main scanning direction. In each of the heating elements 41A, the main scanning central portion 431 and the pair of main scanning side portions 432A and 432B are connected in parallel between the first electrode portion and the second electrode portion. Therefore, the voltage applied to the main scanning central portion 431 and the pair of main scanning side portions 432A and 432B is approximately the same. Thus, in the main scanning central portion 431, where the unit resistance value in the main scanning direction is larger than that of each main scanning side portion 432A and 432B, heat generation can be suppressed. That is, heat generation in the central portion of each heating element 41A in the main scanning direction x can be suppressed. Therefore, the thermal printhead A1 can alleviate heat concentration in the central portion of each heating element 41A, thereby preventing excessive heat generation in the central portion of each heating element 41B and improving printing efficiency.

[0096] In the thermal printhead A1, viewed in the thickness direction z, the portion of the first conductor layer 301 exposed from the second conductor layer 302 is in contact with each heating element 41A in the wiring layer 3. In the first conductor layer 301, the resistance per unit length along the sub-scanning direction y is lower than the resistance of the resistive layer 4 (each heating element 41A) and higher than the resistance of the second conductor layer 302. Since the resistance values ​​of the first conductor layer 301, the second conductor layer 302, and the resistive layer 4 are in the aforementioned relationship, the heat generated in the first conductor layer 301 exposed from the second conductor layer 302 is less than the heat generated in each heating element 41A, but greater than the heat generated in the portion where the first conductor layer 301 and the second conductor layer 302 are stacked. With this configuration, the temperature gradient in the sub-scanning direction y can be mitigated from the wiring layer 3 toward each heating element 41A.

[0097] Figure 15 This refers to the thermal printhead A2 of the second embodiment. Figure 15 This is an enlarged plan view showing the main parts of the thermal printhead A2, and... Figure 3 Correspondingly, compared to thermal printhead A1, thermal printhead A2 has a resistive layer 4 with individual heating elements 41B instead of individual heating elements 41A.

[0098] Each heating element 41B, like each heating element 41A, includes a sub-scanning central portion 421 and a pair of sub-scanning side portions 422A and 422B. However, in each heating element 41B, as... Figure 15 As shown, the dimensions along the main scanning direction x of the sub-scanning central portion 421 are approximately the same as the dimensions along the main scanning direction x of the pair of sub-scanning side portions 422A and 422B.

[0099] Each heating element 41B, like each heating element 41A, includes a main scanning central portion 431 and a pair of main scanning side portions 432A and 432B. However, in each heating element 41B, as... Figure 15 As shown, viewed in the thickness direction z, the boundaries L221, L222 of the pair of main scanning side portions 432A, 432B and each strip portion 331 are located upstream in the sub-scanning direction y compared to the boundary L21 of the main scanning center portion 431 and each strip portion 331. Furthermore, as... Figure 15 As shown, viewed in the thickness direction z, the boundaries L121 and L122 of the pair of main scanning side portions 432A and 432B with the strip portion 313 or strip portion 321 are located downstream of the boundary L11 of the main scanning center portion 431 and the strip portion 313 or strip portion 321 in the sub-scanning direction y. Therefore, in each heating portion 41B, the dimension along the sub-scanning direction y of the main scanning center portion 431 is larger than the dimensions along the sub-scanning direction y of the pair of main scanning side portions 432A and 432B.

[0100] The unit resistance value R21 of the main scanning central part 431 of each heating element 41B in the main scanning direction is greater than the unit resistance value R22 of the main scanning direction of the pair of main scanning side parts 432A and 432B. Figure 15 In the example shown, the dimension along the sub-scanning direction y of the main scan center portion 431 is larger than the dimension along the sub-scanning direction y of the main scan sides 432A and 432B. Since resistance is proportional to the length of the conductor, when the dimensions along the main scanning direction x of the main scan center portion 431 and each of the main scan sides 432A and 432B are the same, the resistance value of the main scan center portion 431 is larger than the individual resistance values ​​of the pair of main scan sides 432A and 432B. Therefore, the unit resistance value R21 of the main scan center portion 431 in the main scanning direction is larger than the unit resistance value R22 of each of the pair of main scan sides 432A and 432B in the main scanning direction.

[0101] In the thermal printhead A2, viewed along the thickness direction (thickness direction z) of the printhead substrate 1, each heating element 41B includes: a main scanning central part 431 located at the center in the main scanning direction x, and a pair of main scanning side parts 432A and 432B arranged sandwiching the main scanning central part 431 in the main scanning direction x. The ends of the main scanning central part 431 and the pair of main scanning side parts 432A and 432B upstream in the sub-scanning direction y are connected to a first electrode part, and the ends downstream in the sub-scanning direction y are connected to a second electrode part. In this embodiment, the first electrode part is also each strip part 321 (each individual electrode 32) or each strip part 313 (common electrode 31), and the second electrode part is each strip part 331 (each relay electrode 33). The unit resistance value R21 of the main scanning central part 431 in the main scanning direction is larger than the unit resistance value R22 of each of the pair of main scanning side parts 432A and 432B in the main scanning direction. In each of the heating elements 41B, the main scanning central portion 431 and the pair of main scanning side portions 432A and 432B are connected in parallel between the first electrode portion and the second electrode portion. Therefore, the voltage applied to the main scanning central portion 431 and the pair of main scanning side portions 432A and 432B is approximately the same. Thus, in the main scanning central portion 431, where the unit resistance value in the main scanning direction is larger than that of each main scanning side portion 432A and 432B, heat generation can be suppressed. That is, heat generation in the central portion of each heating element 41B in the main scanning direction x can be suppressed. Since the thermal printhead A2 can alleviate heat concentration in the central portion of each heating element 41B, excessive heat generation in the central portion of each heating element 41B can be prevented, and printing efficiency can be improved.

[0102] In the thermal printhead A2, the main scanning central portion 431 protrudes to both sides of the pair of main scanning side portions 432A and 432B in the sub-scanning direction y, respectively. With this configuration, the dimension along the sub-scanning direction y of the main scanning central portion 431 can be larger than the respective dimensions along the sub-scanning direction y of the pair of main scanning side portions 432A and 432B. Furthermore, this protruding portion is formed, for example, in a heating element that was previously considered to be rectangular in shape (see reference). Figure 15 The area where the wiring layer 3 is disposed (two dashed lines) is located. That is, in the past heating element, a portion of the resistive layer 4 was disposed in the area formed by the wiring layer 3, so that the formation area of ​​each sub-scanning side portion 422A, 422B of the heating element 41B is larger than that of the past heating element. Since the resistance value of the resistive layer 4 is greater than that of the wiring layer 3 (the first electrode portion and the second electrode portion), the resistance value in each sub-scanning side portion 422A, 422B is larger than that of the past heating element. As described above, the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A, 422B are connected in parallel between the first electrode portion and the second electrode portion. Therefore, by increasing the resistance value of each sub-scanning side portion 422A, 422B, the heat generation in each sub-scanning side portion 422A, 422B increases. The thermal printhead A2 can alleviate the heat concentration in the central portion of the sub-scanning direction y of each heating element 41B, thus improving printing efficiency.

[0103] Figure 16 This refers to the thermal printhead A3 of the third embodiment. Figure 16 This is an enlarged plan view showing the main parts of the A3 thermal printhead, and... Figure 3 Correspondingly, compared to thermal printhead A1, thermal printhead A3 has individual heating elements 41C instead of individual heating elements 41A in resistive layer 4.

[0104] Each heating element 41C, like each heating element 41A, includes a sub-scanning central portion 421 and a pair of sub-scanning lateral portions 422A and 422B. For example... Figure 16 As shown, the dimensions of each heating element 41C and each heating element 41B along the main scanning direction x of the sub-scanning center portion 421 are approximately the same as the dimensions along the main scanning direction x of the pair of sub-scanning side portions 422A and 422B.

[0105] Each heating element 41C, like each heating element 41A, includes a central main scanning element 431 and a pair of side main scanning elements 432A and 432B. For example... Figure 16As shown, each heating element 41C, like each heating element 41B, when viewed in the thickness direction z, has its boundaries L221, L222 of the pair of main scanning side portions 432A, 432B and each strip portion 331 located upstream in the sub-scanning direction y compared to the boundary L21 of the main scanning center portion 431 and each strip portion 331. Furthermore, as... Figure 16 As shown, viewed in the thickness direction z, the boundaries L121, L122 of the pair of main scanning side portions 432A, 432B and the strip portion 313 (or strip portion 321) are located downstream of the boundary L11 of the main scanning central portion 431 and the strip portion 313 (or strip portion 321) in the sub-scanning direction y. Therefore, in each heating portion 41C, similar to each heating portion 41B, the dimension along the sub-scanning direction y of the main scanning central portion 431 is larger than the dimensions along the sub-scanning direction y of the pair of main scanning side portions 432A, 432B.

[0106] The thermal printhead A3 can achieve the same effect as the thermal printhead A2.

[0107] Figure 17 and Figure 18 This refers to the thermal printhead A4 in the fourth embodiment. Figure 17 This is an enlarged plan view of the main parts of the thermal printhead on an A4 sheet, and it is related to... Figure 3 correspond. Figure 18 It is along Figure 17 Enlarged cross-sectional view of the main part of the XVIII-XVIII line. Compared with thermal printhead A1, thermal printhead A4 has individual heating elements 41D instead of individual heating elements 41A in resistive layer 4.

[0108] Each heating element 41D, like each heating element 41A, includes a sub-scanning central portion 421 and a pair of sub-scanning side portions 422A and 422B. However, unlike each heating element 41A, each heating element 41D has approximately the same dimensions along the main scanning direction x of the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A and 422B. Furthermore, in each heating element 41D, as... Figure 17 and Figure 18 As shown, unlike the individual heating elements 41A, a covering element 45 is formed on the sub-scanning central part 421.

[0109] like Figure 17 As shown, the cover portion 45, viewed in the thickness direction z, connects one end to the other in the main scanning direction x of the sub-scan center portion 421. The cover portion 45 is a strip-shaped portion extending in the main scanning direction x, viewed in the thickness direction z. Figure 17In the example shown, the cover portion 45 covers the central portion of the sub-scanning central portion 421 in the sub-scanning direction y. The cover portion 45 is made of a material whose resistance per unit length along the sub-scanning direction y is lower than that of the resistive layer 4. As a result, in the heating portion 41D, the resistance of the portion covered by the cover portion 45 is smaller than that of the portion not covered by the cover portion 45. The constituent material of the cover portion 45 is, for example, the same as the constituent material of the first conductor layer 301, which is Ti in one example. The constituent material of the cover portion 45 may also be different from the constituent material of the first conductor layer 301, for example, it may be a material in which Cu is laminated on Ti. When the material of the cover portion 45 is the same as that of the first conductor layer 301, the cover portion 45 is formed by retaining the first conductor film 301K in the region where the cover portion 45 is disposed during the first part removal process described above.

[0110] In each heating element 41D, since a covering portion 45 is formed on the sub-scanning central portion 421, the resistance value of the portion of the sub-scanning central portion 421 covered by the covering portion 45 is reduced. As a result, in each heating element 41D, the unit resistance value R11 of the sub-scanning central portion 421 in the sub-scanning direction is smaller than the unit resistance value R12 of each sub-scanning direction of the pair of sub-scanning side portions 422A and 422B.

[0111] Each heating element 41D, like each heating element 41A, includes a central main scanning element 431 and a pair of side main scanning elements 432A and 432B. For example... Figure 17 As shown, each heating element 41D is similar to each heating element 41A in that its dimensions along the sub-scanning direction y of the main scan center portion 431 and the pair of main scan side portions 432A and 432B are approximately the same.

[0112] In thermal printhead A4, similar to thermal printhead A1, the unit resistance value R11 of the sub-scanning central portion 421 in the sub-scanning direction is smaller than the unit resistance value R12 of each of the pair of sub-scanning side portions 422A and 422B in the sub-scanning direction. Thus, in the sub-scanning central portion 421, where the unit resistance value in the sub-scanning direction is smaller than that of each of the sub-scanning side portions 422A and 422B, heat generation can be suppressed. That is, heat generation in the central portion of each heat-generating portion 41D in the sub-scanning direction y can be suppressed. Therefore, thermal printhead A4, like thermal printhead A1, can alleviate heat concentration in the central portion of each heat-generating portion 41D, thereby improving printing efficiency.

[0113] Figure 19 and Figure 20 This refers to the thermal printhead A5 in the fifth embodiment. Figure 19 This is an enlarged plan view showing the main parts of the A5 thermal printhead, and... Figure 3 correspond. Figure 20 It is along Figure 19The enlarged cross-sectional view of the main part of the XX-XX line. Compared with thermal printhead A1, thermal printhead A5 has individual heating elements 41E instead of individual heating elements 41A in resistive layer 4.

[0114] Each heating element 41E, like each heating element 41A, includes a sub-scanning central portion 421 and a pair of sub-scanning side portions 422A and 422B. However, unlike each heating element 41A, each heating element 41E has approximately the same dimensions along the main scanning direction x of the sub-scanning central portion 421 and the pair of sub-scanning side portions 422A and 422B.

[0115] Each heating element 41E, like each heating element 41A, includes a main scanning central portion 431 and a pair of main scanning side portions 432A and 432B. However, in each heating element 41E, as... Figure 19 and Figure 20 As shown, a slit 44 is provided in the central part 431 of the main scan.

[0116] The slit 44 extends in the sub-scanning direction y when viewed in the thickness direction z, connecting the upstream end of each heating element 41E in the sub-scanning direction y to the downstream end in the sub-scanning direction y. Figure 19 and Figure 20 In the example shown, slit 44 is formed in the central portion of the main scan direction x in the main scan central portion 431. For example... Figure 19 and Figure 20 As shown, the central portion 431 of the main scan is separated into a pair of separated portions 441 arranged in the main scan direction x by a slit 44. The pair of separated portions 441 are arranged with an insulating layer 19 sandwiched between them when viewed in the thickness direction z in the main scan direction x. For example, a protective layer 2 is filled in the slit 44. The slit 44 is formed, for example, in the resistive film removal process described above.

[0117] In each heating element 41E, since a slit 44 is formed on the central part 431 of the main scan, the resistance value of the central part 431 of the main scan increases compared to the case where the slit 44 is not formed. This is because the area of ​​the cross-section orthogonal to the direction of current flow (sub-scanning direction y) is reduced by the slit 44. As a result, in each heating element 41E, the unit resistance value R21 of the central part 431 of the main scan in the main scan direction is larger than the unit resistance value R22 of the pair of main scan side parts 432A, 432B in the main scan direction. Furthermore, the boundary L21 used in calculating the unit resistance value R21 of the central part 431 of the main scan in the main scan direction also includes the boundary portion of the slit 44 and the strip portion 331, and the boundary L11 used in the calculation also includes the boundary portion of the slit 44 and the strip portion 321 or the strip portion 313.

[0118] In thermal printhead A5, similar to thermal printhead A2, the unit resistance value R21 of the main scanning central portion 431 in the main scanning direction is greater than the unit resistance value R22 of each of the pair of main scanning side portions 432A and 432B in the main scanning direction. Therefore, in the main scanning central portion 431, where the unit resistance value in the main scanning direction is greater than that of each of the main scanning side portions 432A and 432B, heat generation can be suppressed. That is, heat generation in the central portion of each heat-generating part 41E in the main scanning direction x can be suppressed. Therefore, like thermal printhead A2, thermal printhead A5 can alleviate heat concentration in the central portion of each heat-generating part 41E, thus improving printing efficiency.

[0119] The structures of the heating elements 41A to 41E illustrated in the first to fifth embodiments are examples only and are not limited thereto. For example, a heating element 41 (see reference 1) may be formed by appropriately combining the structures of the heating elements 41A to 41E. Figures 21-26 ). Figures 21-26 This is an enlarged plan view showing the main part of the thermal printhead in this modified example, and... Figure 3 Corresponding. The following is about... Figures 21-26 Please provide an explanation.

[0120] Figure 21 The heating element 41 shown is a structure formed by combining the heating element 41A in the first embodiment and the heating element 41B in the second embodiment. Therefore, in Figure 21 In the example shown, each heating element 41, like each heating element 41A, is able to suppress the heating of the central part in the sub-scanning direction y, and like each heating element 41B, is able to suppress the heating of the central part in the main scanning direction x.

[0121] Figure 22 The heating element 41 shown is a structure formed by combining the heating element 41A in the first embodiment and the heating element 41C in the third embodiment. Therefore, in Figure 22 In the example shown, each heating element 41, like each heating element 41A, is able to suppress the heating of the central part in the sub-scanning direction y, and like each heating element 41C, is able to suppress the heating of the central part in the main scanning direction x.

[0122] Figure 23 The heating element 41 shown is a structure formed by combining the heating element 41B in the second embodiment and the heating element 41D in the fourth embodiment. Therefore, in Figure 23 In the example shown, each heating element 41, like each heating element 41B, is able to suppress the heating of the central part in the main scanning direction x, and like each heating element 41D, is able to suppress the heating of the central part in the sub-scanning direction y.

[0123] Figure 24The heating element 41 shown is a structure formed by combining the heating element 41C in the third embodiment and the heating element 41D in the fourth embodiment. Therefore, in Figure 24 In the example shown, each heating element 41, like each heating element 41C, is able to suppress the heating of the central part in the main scanning direction x, and like each heating element 41D, is able to suppress the heating of the central part in the sub-scanning direction y.

[0124] Figure 25 The heating element 41 shown is a structure formed by combining the heating element 41A in the first embodiment and the heating element 41E in the fifth embodiment. Therefore, in Figure 25 In the example shown, each heating element 41, like each heating element 41A, is able to suppress the heating of the central part in the sub-scanning direction y, and like each heating element 41E, is able to suppress the heating of the central part in the main scanning direction x.

[0125] Figure 26 The heating element 41 shown is a structure formed by combining the heating element 41D in the fourth embodiment and the heating element 41E in the fifth embodiment. Therefore, in Figure 26 In the example shown, each heating element 41, like each heating element 41D, can suppress the heating of the central part in the sub-scanning direction y, and like each heating element 41E, can suppress the heating of the central part in the main scanning direction x.

[0126] In the first and fifth embodiments, the construction of the wiring layer 3 is not limited to the examples described above; for example, it can be constructed using... Figure 27 The structure shown. Figure 27 This is an enlarged plan view showing the main part of the thermal printhead in this modified example, and is related to... Figure 2 Corresponding. In this variant example, such as Figure 27 As shown, the resistive layer 4 has multiple heating elements 41A, but multiple heating elements 41, 41B to 41E can be used instead of multiple heating elements 41A.

[0127] exist Figure 27 In the modified example shown, the wiring layer 3 has a common electrode 31 and a plurality of individual electrodes 32. That is, the wiring layer 3 of this thermal printhead does not have a plurality of relay electrodes 33 compared with the wiring layer 3 of thermal printhead A1.

[0128] like Figure 27As shown, the common electrode 31 in this modified example includes multiple strip-shaped portions 313, connecting portions 314, and detour portions 315. The connecting portions 314 are disposed near the downstream edge of the printhead substrate 1 in the sub-scanning direction y. The connecting portions 314 are strip-shaped portions extending in the main scanning direction x. Multiple strip-shaped portions 313 extend from the connecting portions 314 in the sub-scanning direction y to each heating portion 41A. The multiple strip-shaped portions 313 are arranged at equal intervals in the main scanning direction x. The detour portions 315 extend from one end of the connecting portions 314 in the main scanning direction x in the sub-scanning direction y.

[0129] like Figure 27 As shown, in this modified example, each heating element 41A is sandwiched between the strip-shaped portions 313 of the common electrode 31 and the strip-shaped portions 321 of each individual electrode 32 in the sub-scanning direction y. Each strip-shaped portion 321 is connected to each heating element 41A from the upstream side of the sub-scanning direction y, and each strip-shaped portion 313 is connected to each heating element 41A from the downstream side of the sub-scanning direction y.

[0130] exist Figure 27 In the thermal printhead shown, similar to thermal printhead A1, each heating element 41A includes a sub-scanning central portion 421 and a pair of sub-scanning side portions 422A and 422B. Of the pair of sub-scanning side portions 422A and 422B, sub-scanning side portion 422A is connected to a first electrode portion, and sub-scanning side portion 422B is connected to a second electrode portion. In this modified example, the first electrode portion is each strip portion 321 (each individual electrode 32), and the second electrode portion is each strip portion 313 (a common electrode 31). Therefore, the thermal printhead in this modified example, like thermal printhead A1, can alleviate heat concentration in the central portion of each heating element 41A, thus preventing excessive heating in the central portion of each heating element 41A and improving printing efficiency.

[0131] In embodiments 1 to 5, an example is shown where the printhead substrate 1 has a protrusion 13, but the protrusion 13 may not be formed on the printhead substrate 1. That is, the first main surface 11 may be a flat surface on the entire printhead substrate 1. In addition, an example is shown where the protrusion 13 has a pair of first inclined portions 131A and 131B, but the pair of first inclined portions 131A and 131B may not be formed on the protrusion 13. That is, in the protrusion 13, a pair of second inclined portions 132A and 132B are connected to the top 130.

[0132] The thermal printhead according to this disclosure is not limited to the embodiments described above. The specific structure of each part of the thermal printhead of this disclosure can be varied in many design modifications. For example, the thermal printhead of this disclosure includes embodiments described in the appendix.

[0133] [Postscript 1]

[0134] A thermal printhead, characterized in that,

[0135] The thermal printhead includes:

[0136] substrate;

[0137] A resistive layer having a plurality of heating elements supported by the substrate and arranged in the main scanning direction;

[0138] A wiring layer supported by the substrate and forming a power path to the plurality of heating elements.

[0139] The wiring layer includes: a first electrode portion connected to one of the plurality of heating elements from the sub-scanning direction; and a second electrode portion connected to the plurality of heating elements from the other of the sub-scanning direction.

[0140] The plurality of heating elements, viewed from the thickness direction of the substrate, include: a sub-scanning central portion located at the center in the sub-scanning direction; and a pair of sub-scanning side portions arranged sandwiching the sub-scanning central portion in the sub-scanning direction.

[0141] One of the pair of sub-scanning side portions is connected to the first electrode portion, and the other is connected to the second electrode portion.

[0142] The unit resistance value of the sub-scanning direction of the central portion of the sub-scanning section is smaller than the unit resistance value of the sub-scanning direction of each of the two pairs of sub-scanning side portions.

[0143] The unit resistance value of the sub-scanning central portion in the sub-scanning direction is the resistance value per unit length in the sub-scanning central portion of the sub-scanning direction.

[0144] The unit resistance value of each sub-scanning direction of the pair of sub-scanning sides is the resistance value per unit length in each sub-scanning direction of the pair of sub-scanning sides.

[0145] [Postscript 2]

[0146] The thermal printhead as described in Appendix 1 is characterized in that,

[0147] The dimension of the central portion of the sub-scan along the main scan direction is larger than the dimensions of each of the pair of side portions of the sub-scan along the main scan direction.

[0148] [Postscript 3]

[0149] The thermal printhead as described in Appendix 2 is characterized in that,

[0150] Compared to the pair of sub-scan side portions, the central portion of the sub-scan protrudes further to both sides in the main scanning direction.

[0151] [Postscript 4]

[0152] The thermal printhead as described in any one of Annexes 1 to 3 is characterized in that,

[0153] The plurality of heating elements includes a covering portion that covers the central portion of the sub-scan.

[0154] The resistance value of the covering part is smaller than that of the resistive layer.

[0155] [Postscript 5]

[0156] The thermal printhead as described in any one of Annexes 1 to 4 is characterized in that,

[0157] The plurality of heating elements includes: a central portion of the main scan located in the center of the main scan direction; and a pair of side portions of the main scan arranged sandwiching the central portion of the main scan in the main scan direction.

[0158] The central portion of the main scan and the pair of side portions of the main scan are respectively connected to the first electrode portion and the second electrode portion.

[0159] The unit resistance value of the central portion of the main scan direction is greater than the unit resistance values ​​of each of the main scan directions of the pair of side portions of the main scan.

[0160] The unit resistance value of the central portion of the main scan in the main scan direction is the resistance value per contact length between the central portion of the main scan and one of the first electrode portion or the second electrode portion in the main scan direction.

[0161] The unit resistance value in the main scanning direction of the pair of main scanning side portions is the resistance value per contact length of the pair of main scanning side portions and one of the first electrode portion or the second electrode portion in the main scanning direction.

[0162] [Postscript 6]

[0163] The thermal printhead as described in Appendix 5 is characterized in that...

[0164] The dimension of the central portion of the main scan along the sub-scanning direction is larger than the dimensions of each of the pair of side portions of the main scan along the sub-scanning direction.

[0165] [Postscript 7]

[0166] The thermal printhead as described in Appendix 6 is characterized in that...

[0167] Viewed in the thickness direction, the boundaries of the pair of main scanning side portions and the first electrode portion are located on the opposite side of the sub-scanning direction compared to the boundaries of the main scanning center portion and the first electrode portion.

[0168] [Postscript 8]

[0169] The thermal printhead as described in Appendix 6 or Appendix 7 is characterized in that...

[0170] Viewed in the thickness direction, the boundaries of the pair of main scanning side portions and the second electrode portion are located on one side of the sub-scanning direction compared to the boundaries of the main scanning center portion and the second electrode portion.

[0171] [Postscript 9]

[0172] The thermal printhead as described in any one of Appendices 5 to 8 is characterized in that...

[0173] It also includes an insulating layer sandwiched between the substrate and the resistive layer.

[0174] [Postscript 10]

[0175] The thermal printhead as described in Appendix 9 is characterized in that...

[0176] A slit is formed in the center of the main scan portion, connecting one side to the other side from the sub-scan direction when viewed in the thickness direction.

[0177] The central portion of the main scan includes a pair of separation portions separated by the slit in the main scan direction.

[0178] The pair of separation portions are arranged with the insulating layer sandwiched between them when viewed from the thickness direction in the main scanning direction.

[0179] [Postscript 11]

[0180] The thermal printhead as described in any one of Appendices 1 to 10 is characterized in that,

[0181] The resistive layer is formed on the substrate.

[0182] The wiring layer includes: a first conductor layer that exposes a portion of the resistive layer and is stacked on the resistive layer; and a second conductor layer that exposes a portion of the first conductor layer and is stacked on the first conductor layer.

[0183] The resistance per unit length of the second conductor layer in the sub-scanning direction is smaller than that of the plurality of heating elements.

[0184] The resistance value per unit length of the first conductor layer in the sub-scanning direction is between the plurality of heating elements and the first conductor layer.

[0185] [Postscript 12]

[0186] The thermal printhead as described in Appendix 11 is characterized in that,

[0187] The first conductor layer is composed of Ti.

[0188] The second conductor layer is composed of Cu.

[0189] [Postscript 13]

[0190] The thermal printhead as described in Appendix 11 or Appendix 12 is characterized in that,

[0191] The portions of the first electrode and the second electrode that are exposed in the second conductor layer in the first conductor layer are connected to the plurality of heating elements when viewed in the thickness direction.

[0192] [Postscript 14]

[0193] The thermal printhead as described in any one of Appendices 1 to 13 is characterized in that,

[0194] The substrate has: a main surface facing one of the thickness directions, and a protrusion protruding from the main surface and extending in the main scanning direction.

[0195] The plurality of heating elements are formed on the protrusion.

[0196] [Postscript 15]

[0197] The thermal printhead as described in any one of Appendices 1 to 14 is characterized in that,

[0198] It also includes a protective layer formed on the substrate and covering the resistive layer and the wiring layer.

[0199] [Postscript 16]

[0200] The thermal printhead as described in any one of Appendices 1 to 15 is characterized in that,

[0201] The substrate is made of a single-crystal semiconductor.

[0202] [Postscript 17]

[0203] The thermal printhead as described in claim 16 is characterized in that,

[0204] The single-crystal semiconductor is Si.

[0205] [Postscript 18]

[0206] A thermal printhead, characterized in that,

[0207] The thermal printhead includes:

[0208] substrate;

[0209] A resistive layer having a plurality of heating elements supported by the substrate and arranged in the main scanning direction;

[0210] A wiring layer supported by the substrate and forming a power path to the plurality of heating elements.

[0211] The wiring layer includes: a first electrode portion connected to one of the plurality of heating elements from the sub-scanning direction; and a second electrode portion connected to the plurality of heating elements from the other of the sub-scanning direction.

[0212] The plurality of heating elements, viewed from the thickness direction of the substrate, include: a main scanning central portion located at the center in the main scanning direction; and a pair of main scanning side portions arranged sandwiching the main scanning central portion in the main scanning direction.

[0213] The central portion of the main scan and the pair of side portions of the main scan are respectively connected to the first electrode portion and the second electrode portion.

[0214] The unit resistance value of the central portion of the main scan direction is greater than the unit resistance value of each of the main scan directions of the pair of side portions of the main scan.

[0215] The unit resistance value of the main scanning direction of the central portion of the main scan is the resistance value per contact length in the main scanning direction of either the central portion of the main scan or the first electrode portion or the second electrode portion.

[0216] The unit resistance value of each main scanning direction of the pair of main scanning sides is the resistance value per contact length in the main scanning direction of the pair of main scanning sides and one of the first electrode or the second electrode.

[0217] Symbol Explanation

[0218] A1~A5: Thermal printheads

[0219] 1: Printhead substrate

[0220] 11: Main side 1

[0221] 12: The first reverse side

[0222] 13: convex part

[0223] 130: Top

[0224] 131A, 131B: First inclined section

[0225] 132A, 132B: Second inclined section

[0226] 1K: Substrate material

[0227] 11K: Main side 1

[0228] 12K: First Back

[0229] 13K: convex part

[0230] 130K: Top

[0231] 132K: Inclined section

[0232] 19: Insulation layer

[0233] 2: Protective layer

[0234] 21: Padding opening

[0235] 3: Wiring layer

[0236] 301: First conductor layer

[0237] 302: Second conductor layer

[0238] 31: Common electrode

[0239] 311: Direct Department

[0240] 312: Branch Office

[0241] 313: Band-like portion

[0242] 314: Connecting Part

[0243] 315: Detour Section

[0244] 32: Individual electrodes

[0245] 321: Band-like portion

[0246] 322: Joint

[0247] 33: Relay Electrode

[0248] 331: Band-like portion

[0249] 332: Connecting Part

[0250] 3K: Wiring film

[0251] 301K: First Conductor Film

[0252] 302K: Second Conductor Film

[0253] 4: Resistor layer

[0254] 41, 41A~41E: Heating section

[0255] 421: Sub-scanning central section

[0256] 422A, 422B: Side Scanning Section

[0257] 431: Main Scan Central Section

[0258] 432A, 432B: Main scanning side section

[0259] 44: Slit

[0260] 441: Separation section

[0261] 45: Covering section

[0262] 4K: Resistive film

[0263] 5: Connecting substrate

[0264] 51: Second main side

[0265] 52: Second back

[0266] 55: Control electrode

[0267] 59: Connector

[0268] 61: Joint line

[0269] 7: Driver IC

[0270] 71: Input Pad

[0271] 72: Output gasket

[0272] 78: Protective resin

[0273] 8: Heat dissipation components

[0274] 81: First support surface

[0275] 82: Second support surface

[0276] 91: Paper pressure roller

[0277] Pr: Thermal printer.

Claims

1. A thermal printhead characterized by comprising: a substrate; a resistor layer having a plurality of heat generating portions supported by the substrate and arranged in a main scanning direction; a wiring layer supported by the substrate and constituting an energization path to the plurality of heat generating portions, the wiring layer including: a first electrode portion connected to the plurality of heat generating portions respectively from one of sub scanning directions; and a second electrode portion connected to the plurality of heat generating portions respectively from the other of the sub scanning directions, the plurality of heat generating portions each including, in the thickness direction of the substrate: a sub scanning central portion located in a central portion in the sub scanning direction; and a pair of sub scanning side portions disposed sandwiching the sub scanning central portion in the sub scanning direction, one of the pair of sub scanning side portions being connected to the first electrode portion, and the other being connected to the second electrode portion, a sub scanning direction unit resistance value of the sub scanning central portion being smaller than each of sub scanning direction unit resistance values of the pair of sub scanning side portions, the sub scanning direction unit resistance value of the sub scanning central portion being a resistance value per unit length in the sub scanning direction of the sub scanning central portion, each of the sub scanning direction unit resistance values of the pair of sub scanning side portions being a resistance value per unit length in the sub scanning direction of each of the pair of sub scanning side portions.

2. The thermal printhead according to claim 1, characterized in that a size of the sub scanning central portion in the main scanning direction is larger than each of sizes of the pair of sub scanning side portions in the main scanning direction.

3. The thermal printhead according to claim 2, characterized in that the sub scanning central portion projects more to both sides in the main scanning direction than the pair of sub scanning side portions.

4. The thermal printhead according to any one of claims 1 to 3, characterized in that each of the plurality of heat generating portions includes a covering portion covering the sub scanning central portion, a resistance value of the covering portion is smaller than the resistor layer.

5. The thermal printhead according to any one of claims 1 to 3, characterized in that each of the plurality of heat generating portions includes: a main scanning central portion located in a central portion in the main scanning direction; and a pair of main scanning side portions disposed sandwiching the main scanning central portion in the main scanning direction, the main scanning central portion and the pair of main scanning side portions are connected to the first electrode portion and the second electrode portion respectively, a main scanning direction unit resistance value of the main scanning central portion is larger than each of main scanning direction unit resistance values of the pair of main scanning side portions, the main scanning direction unit resistance value of the main scanning central portion is a resistance value per contact length in the main scanning direction of the main scanning central portion and one of the first electrode portion or the second electrode portion, each of the main scanning direction unit resistance values of the pair of main scanning side portions is a resistance value per contact length in the main scanning direction of each of the pair of main scanning side portions and one of the first electrode portion or the second electrode portion.

6. The thermal printhead according to claim 5, characterized in that ​ The size of the main scan central portion in the sub-scanning direction is larger than each of the sizes of the pair of main scan side portions in the sub-scanning direction.

7. The thermal printhead according to claim 6, wherein The boundary between the pair of main scan side portions and the first electrode portion is located on the other side in the sub-scanning direction as compared with the boundary between the main scan central portion and the first electrode portion, as viewed in the thickness direction.

8. The thermal printhead according to claim 6, wherein The boundary between the pair of main scan side portions and the second electrode portion is located on one side in the sub-scanning direction as compared with the boundary between the main scan central portion and the second electrode portion, as viewed in the thickness direction.

9. The thermal printhead according to claim 5, further comprising an insulating layer interposed between the substrate and the resistive body layer.

10. The thermal printhead according to claim 9, wherein A slit is formed in the main scan central portion, which connects from one side to the other side in the sub-scanning direction as viewed in the thickness direction, The main scan central portion includes a pair of separated portions separated by the slit in the main scanning direction, The pair of separated portions are arranged sandwiching the insulating layer in the main scanning direction as viewed in the thickness direction.

11. The thermal printhead according to any one of claims 1 to 3, wherein The resistive body layer is formed on the substrate, The wiring layer includes a first conductor layer which exposes a part of the resistive body layer and is laminated on the resistive body layer, and a second conductor layer which exposes a part of the first conductor layer and is laminated on the first conductor layer, The second conductor layer has a smaller resistance value per unit length in the sub-scanning direction than the plurality of heat generating portions, The first conductor layer has a resistance value per unit length in the sub-scanning direction between the plurality of heat generating portions and the first conductor layer.

12. The thermal printhead according to claim 11, wherein The first conductor layer is made of Ti, The second conductor layer is made of Cu.

13. The thermal printhead according to claim 11, wherein The first electrode portion and the second electrode portion are connected to the plurality of heat generating portions as viewed in the thickness direction with respect to the parts of the first conductor layer exposed from the second conductor layer.

14. The thermal printhead according to any one of claims 1 to 3, wherein The substrate has a main surface toward one of the thickness directions, and a protrusion which protrudes from the main surface and extends in the main scanning direction, The plurality of heat generating portions are formed on the protrusion, respectively.

15. The thermal printhead according to any one of claims 1 to 3, further comprising a protective layer formed on the substrate and covering the resistive body layer and the wiring layer.

16. The thermal printhead according to any one of claims 1 to 3, wherein The substrate is made of a single-crystal semiconductor.

17. The thermal printhead according to claim 16, wherein The single-crystal semiconductor is Si.

18. A thermal printhead, comprising: ​ ​ ​ Substrate A resistor layer having a plurality of heat generating portions supported by the substrate and arranged in a main scanning direction A wiring layer supported by the substrate and constituting an energization path to the plurality of heat generating portions, The wiring layer includes: a first electrode portion connected to each of the plurality of heat generating portions from one of sub scanning directions; and a second electrode portion connected to each of the plurality of heat generating portions from the other of the sub scanning directions, Each of the plurality of heat generating portions includes, as viewed in a thickness direction of the substrate: a main scanning central portion located in a central portion in the main scanning direction; and a pair of main scanning side portions arranged sandwiching the main scanning central portion in the main scanning direction, The main scanning central portion and the pair of main scanning side portions are connected to the first electrode portion and the second electrode portion, respectively, The main scanning direction unit resistance value of the main scanning central portion is larger than each of the main scanning direction unit resistance values of the pair of main scanning side portions, The main scanning direction unit resistance value of the main scanning central portion is a resistance value per contact length in the main scanning direction of the main scanning central portion and one of the first electrode portion and the second electrode portion, Each of the main scanning direction unit resistance values of the pair of main scanning side portions is a resistance value per contact length in the main scanning direction of the pair of main scanning side portions and one of the first electrode portion and the second electrode portion.

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