Thermal head and recording device

Abstract

The thermal head according to this disclosure has a plurality of heating elements arranged in a first direction and at least one wiring. The wiring has a plurality of first parts and at least one second part. The first parts extend in a first direction. The second parts extend in a second direction intersecting the first direction and connect two first parts that are adjacent in the first direction.

Description

Technical Field

[0006]

[0001] The present disclosure relates to a thermal head, a recording device, and a method for manufacturing a thermal head.

Background Art

[0002] Conventionally, various thermal heads have been proposed as printing devices such as facsimiles or video printers. In such a thermal head, a technique for forming a wiring pattern by gravure offset printing is known. <00000​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ [Figure 2] Figure 2 is a schematic plan view of the thermal head shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view taken along line III-III in Figure 2. [Figure 4] Figure 4 is a plan view showing an example of the first connection wiring according to the first embodiment. [Figure 5] Figure 5 is a plan view showing another example of the first connecting wiring according to the first embodiment. [Figure 6] Figure 6 is a plan view showing another example of the first connecting wiring according to the first embodiment. [Figure 7] Figure 7 is a plan view showing another example of the first connecting wiring according to the first embodiment. [Figure 8] Figure 8 is a plan view showing another example of the first connecting wiring according to the first embodiment. [Figure 9] Figure 9 is a plan view showing an example of the first connection wiring according to the second embodiment. [Figure 10] Figure 10 is a plan view showing another example of the first connection wiring according to the second embodiment. [Figure 11] Figure 11 is a plan view showing another example of the first connecting wiring according to the second embodiment. [Figure 12] Figure 12 is a plan view showing another example of the first connection wiring according to the second embodiment. [Figure 13] Figure 13 is a plan view showing an example of the first connection wiring according to the third embodiment. [Figure 14] Figure 14 is a schematic diagram of a thermal printer according to the first, second, or third embodiment. [Modes for carrying out the invention]

[0007] The following describes in detail, with reference to the drawings, embodiments for carrying out the thermal head, recording device, and method for manufacturing the thermal head according to this disclosure. However, this disclosure is not limited by these embodiments. Furthermore, each embodiment can be combined as appropriate, provided that the processing content is not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the following embodiments, and redundant descriptions are omitted.

[0008] Furthermore, in the embodiments described below, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not require strict adherence to "constant," "orthogonal," "perpendicular," or "parallel" conditions. In other words, each of the above expressions allows for deviations such as manufacturing accuracy or installation accuracy.

[0009] Furthermore, in the drawings referenced below, for the sake of clarity, mutually orthogonal X, Y, and Z axes are sometimes defined, and a Cartesian coordinate system is shown with the positive Z-axis direction as the vertically upward direction.

[0010] (First Embodiment) Figure 1 is an exploded perspective view showing a schematic of the thermal head X1 according to the first embodiment. As shown in Figure 1, the thermal head X1 according to the first embodiment includes a heat sink 1, an adhesive member 2, a head base 3, and a connector 4. Note that the heat sink 1, adhesive member 2, and connector 4 are not necessarily required.

[0011] The heat sink 1 dissipates excess heat from the head base 3. The adhesive member 2 adheres the heat sink 1 and the head base 3 together. The head base 3 is placed on the heat sink 1 via the adhesive member 2. The head base 3 prints onto the recording medium P (see Figure 14) when an external voltage is applied. The connector 4 electrically connects the head base 3 to the outside.

[0012] The heat sink 1 has a rectangular parallelepiped shape. The heat sink 1 is formed of a metal material such as copper, iron, or aluminum, and dissipates heat that does not contribute to printing among the heat generated in the heat generating portion 9a of the head base 3.

[0013] The bonding member 2 is located on the heat sink 1. The bonding member 2 joins the head base 3 and the heat sink 1. Examples of the bonding member 2 include a double-sided tape or a resinous adhesive.

[0014] The head base 3 is rectangular in plan view, and each member constituting the thermal head X1 is arranged on the substrate 5. The head base 3 performs printing on the recording medium P (see FIG. 14) according to an electrical signal supplied from the outside.

[0015] Next, each member constituting the thermal head X1 will be further described with reference to FIGS. 2 to 4. FIG. 2 is a plan view showing an outline of the thermal head X1 shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2. FIG. 4 is a plan view showing an example of the first connection wiring 63 according to the first embodiment. In FIG. 2, the covering member 10 is shown by a dashed line, and the description of the protective layer 11 and the covering layer 12 is omitted. Also, in FIGS. 4 to 13, the first connection wiring 63 is shown by hatching.

[0016] The head base 3 includes a substrate 5, a plurality of wirings 6, a plurality of connection terminals 7, a plurality of drive ICs (Integrated Circuits) 8, a resistor layer 9, a covering member 10, a protective layer 11, and a covering layer 12. Note that not all of these members are necessarily provided. Also, the head base 3 may include members other than these.

[0017] The substrate 5 is arranged on the heat sink 1 and is rectangular in plan view. As shown in FIG. 3, the substrate 5 has a first surface 5a, a second surface 5b, and a side surface 5c.

[0018] The first surface 5a has a first long side 5d, a second long side 5e, a first short side 5f, and a second short side 5g. The components constituting the head base 3 are arranged on the first surface 5a.

[0019] The second surface 5b is located on the opposite side from the first surface 5a. The second surface 5b is located on the heat sink 1 side and is joined to the heat sink 1 via the adhesive member 2. The side surface 5c connects the first surface 5a and the second surface 5b and is located on the second long side 5e side.

[0020] The substrate 5 is formed from, for example, an electrically insulating material such as alumina ceramics or a semiconductor material such as single-crystal silicon.

[0021] The substrate 5 may have a heat storage layer 13. The heat storage layer 13 is located on the first surface 5a of the substrate 5. The heat storage layer 13 is located away from the first long side 5d of the substrate 5. The heat storage layer 13 protrudes from the first surface 5a in the thickness direction of the substrate 5 (here, the positive Z-axis direction) and extends in a strip shape along the first direction (here, the negative Y-axis direction). The heat storage layer 13 has the function of pressing the recording medium P (see Figure 14) to be printed onto the protective layer 11 located on the heat-generating part 9a.

[0022] The heat storage layer 13 may also have a base portion (not shown) that extends over the entire area of ​​the first surface 5a side of the substrate 5.

[0023] The heat storage layer 13 contains, for example, a glass component. The heat storage layer 13 temporarily stores a portion of the heat generated in the heat-generating section 9a. This allows the heat storage layer 13 to shorten the time required to raise the temperature of the heat-generating section 9a. In other words, the heat storage layer 13 has the function of improving the thermal response characteristics of the thermal head X1.

[0024] The heat storage layer 13 is manufactured, for example, by applying a predetermined glass paste obtained by mixing glass powder with a suitable organic solvent to the first surface 5a of the substrate 5 by conventionally known screen printing or the like, and then firing it. The substrate 5 may have only a base portion as the heat storage layer 13.

[0025] Multiple wirings 6 are located on the first surface 5a of the substrate 5. Multiple wirings 6 constitute a conductive path for energizing the heat-generating section 9a and the drive IC 8. Multiple wirings 6 include a common wiring 61, multiple individual wirings 62, multiple first connection wirings 63, and multiple second connection wirings 64.

[0026] The common wiring 61 is located on the first surface 5a of the substrate 5. The common wiring 61 comprises main wiring sections 61a and 61d, a secondary wiring section 61b, and a plurality of lead sections 61c. The common wiring 61 electrically connects the plurality of heating elements 9a to the connector 4. The main wiring section 61a extends along the first long side 5d of the substrate 5. The secondary wiring section 61b extends along the first short side 5f and the second short side 5g of the substrate 5, respectively. The plurality of lead sections 61c are arranged at predetermined intervals in the first direction (here, the negative Y-axis direction). Each lead section 61c extends from the main wiring section 61a toward the heating element 9a, with a portion inserted to the opposite side of the heating element 9a. The main wiring section 61d extends along the second long side 5e of the substrate 5.

[0027] The individual wiring 62 is located on the first surface 5a of the circuit board 5. The individual wiring 62 electrically connects the heat-generating element 9a and the drive IC 8. The multiple heat-generating elements 9a are divided into multiple groups. The individual wiring 62 electrically connects each heat-generating element 9a constituting each group to the corresponding drive IC 8.

[0028] The individual wiring 62 is electrically connected to the drive IC 8 by a bonding material 24. The bonding material 24 is conductive. The bonding material 24 may contain gold (Au) and / or tin (Sn). The material of the bonding material 24 may be, for example, AuSn, SnAg, SnAgCu, SnAgCuNi, Sn, or Au. Such a bonding material 24 has high mechanical strength, such as shear stress, and is less likely to peel off from the individual wiring 62, thus providing high durability.

[0029] Multiple individual wirings 62 are positioned along a first direction (in this case, the negative Y-axis direction). Each individual wiring 62 is located between two adjacent lead portions 61c. Therefore, in the thermal head X1, the lead portions 61c and individual wirings 62 are arranged alternately at predetermined intervals in the first direction.

[0030] Multiple first connection wires 63 electrically connect the drive IC 8 and the connector 4.

[0031] Multiple second connection wires 64 electrically connect adjacent drive ICs 8.

[0032] The common wiring 61, individual wiring 62, first connecting wiring 63, and second connecting wiring 64 are formed of a conductive material. The material of the common wiring 61, individual wiring 62, first connecting wiring 63, and second connecting wiring 64 may be, for example, one of the metals Al, Au, Cu, or Ag, or an alloy containing these metallic elements.

[0033] The thickness of the individual wiring 62 is, for example, 3.0 μm or less, and may be, for example, around 0.1 μm to 3.0 μm. This makes it less likely for heat generated in the heat-generating section 9a to dissipate through the individual wiring 62. In addition, by reducing the step difference with the substrate 5, for example, the protective layer 11 covering the heat-generating section 9a becomes less likely to peel off, improving the reliability of the thermal head X1.

[0034] Furthermore, the thickness of the various wirings other than the individual wiring 62 may be, for example, about 0.1 μm to 15 μm, or for example, about 0.3 μm to 5 μm. Note that the thickness of the various wirings other than the individual wiring 62 may be the same as the thickness of the individual wiring 62.

[0035] Multiple connection terminals 7 are located on the second long side 5e of the circuit board 5. Each connection terminal 7 connects the common wiring 61 or the first connection wiring 63 to the connector 4. Each connection terminal 7 may be located corresponding to the connector pins (not shown) of the connector 4. When connecting the connector 4, the connector pins and connection terminals 7 may be connected so that they are electrically independent of each other.

[0036] Multiple drive ICs 8 are located on the first surface 5a side of the substrate 5. The multiple drive ICs 8 are located along the arrangement direction of the heat-generating parts 9a (here, the negative Y-axis direction). Each drive IC 8 is located in correspondence with the multiple heat-generating parts 9a assigned to each drive IC 8. Each drive IC 8 is connected to multiple individual wirings 62 and multiple first connection wirings 63 and second connection wirings 64. The drive ICs 8 control the energized state of the heat-generating parts 9a. The drive ICs 8 supply power to each heat-generating part 9a individually according to an electrical signal supplied from the outside. As the drive ICs 8, for example, a switching IC having multiple switching elements inside can be used.

[0037] The resistive layer 9 spans the lead portions 61c of the common wiring 61 and the individual wiring 62, and is located away from the first long side 5d of the substrate 5. The portions of the resistive layer 9 located between the lead portions 61c and the individual wiring 62 each function as heat-generating portions 9a. In other words, multiple heat-generating portions 9a are arranged at predetermined intervals in the first direction (here, the negative Y-axis direction). Each heat-generating portion 9a may be located at a density of, for example, 100 dpi (dots per inch) or more. Furthermore, each heat-generating portion 9a may be located at a density of 200 to 2400 dpi.

[0038] The thickness of the resistor layer 9 is, for example, about 3 to 6 μm. The sheet resistance of the resistor layer 9 is, for example, about 500 to 8000 Ω / □. The thermal expansion coefficient of the resistor layer 9 is, for example, about 5 to 10 ppm / °C. The thermal conductivity of the resistor layer 9 is, for example, about 0.5 to 2 W / (m·K).

[0039] The resistive layer 9 may be formed, for example, by positioning a material paste containing a conductive component and a glass component in a long strip in the main scanning direction on a substrate 5 patterned with various electrodes using a screen printing method or a dispensing device. The conductive component may include, for example, ruthenium oxide. The glass component may include, for example, lead borosilicate glass.

[0040] The covering member 10 is a member that seals the drive IC 8, the individual wiring 62, the first connecting wiring 63, and the second connecting wiring 64 while they are connected. The covering member 10 is arranged to extend in the first direction (here, the negative Y-axis direction) and integrally seals multiple drive ICs 8. For the covering member 10, a resin material such as epoxy resin or silicone resin can be used.

[0041] The protective layer 11 is located on the first surface 5a side of the substrate 5. The protective layer 11 covers the heat-generating portion 9a. The protective layer 11 is located across the first direction (negative Y-axis direction) of the substrate 5.

[0042] The protective layer 11 protects the covered area from corrosion caused by the adhesion of moisture contained in the atmosphere, or from abrasion caused by contact with the recording medium P (see Figure 14) on which printing is performed. For example, SiN, SiON, Si2, SiAlON, TiN, TiON, TiCrN, or TiAlON can be used as the protective layer 11.

[0043] The coating layer 12 is located on the first surface 5a side of the substrate 5. The coating layer 12 partially covers the common wiring 61, individual wiring 62, first connecting wiring 63, and second connecting wiring 64. The coating layer 12 protects the covered area from oxidation due to contact with the atmosphere or corrosion due to the adhesion of moisture contained in the atmosphere. For example, a resin material such as epoxy resin, polyimide resin, or silicone resin can be used as the coating layer 12.

[0044] The wiring 6 that constitutes the head base 3 described above can be formed, for example, by gravure offset printing. The method for forming the wiring 6 by gravure offset printing is as follows: First, printing paste is filled into the recesses of the gravure plate with a doctor blade. Next, the printing paste is transferred to a blanket. Then, the printing paste transferred to the blanket is transferred to the object to be printed, such as a substrate. Finally, the wiring 6 is formed by firing the printing paste.

[0045] However, when forming wiring 6 by gravure offset printing, if the dimensions of the recess in a direction perpendicular to the direction of travel of the doctor blade or blanket are relatively large, bleeding or indentation may occur in the printing paste transferred to the blanket, potentially leading to a decrease in print quality.

[0046] Specifically, when filling the recesses of a gravure plate with printing paste using a doctor blade, if the dimensions of the recesses perpendicular to the direction of the doctor blade's movement are relatively large, the following problems can occur: the doctor blade may sink into the recesses, scraping off too much printing paste, or the printing paste may splatter when the doctor blade emerges from the recesses. Also, when transferring the printing paste from the recesses of the gravure plate to the blanket, if the dimensions of the recesses perpendicular to the direction of the blanket's movement are relatively large, the blanket may sink deeply into the recesses. As a result, bleeding or indentations may occur in the printing paste transferred to the blanket, raising concerns about a decrease in print quality.

[0047] In this regard, Patent Document 1 discloses a thermal print head in which at least one of the multiple wirings has multiple edges that intersect with respect to the main scanning direction and multiple voids that penetrate in the thickness direction and are located between two adjacent edges. For example, Patent Document 1 discloses wiring that has a jagged shape (wave shape) in plan view. According to this, when forming wiring in gravure offset printing, the blanket sinking deeply into the recesses corresponding to the wiring is reduced.

[0048] However, in the technology described in Patent Document 1, the wiring width may widen at the peaks and valleys of the jagged wiring, which increases the risk of short circuits with adjacent wiring. In addition, the design flexibility of the wiring is reduced.

[0049] Therefore, the wiring 6 of the thermal head X1 according to the first embodiment is configured to extend in a stepped manner along a first direction (here, the negative Y-axis direction). The first direction here is, for example, the main scanning direction of the thermal head X1. The first direction is, for example, the direction perpendicular to the direction of travel of the doctor blade or blanket in the wiring 6 formation process.

[0050] Specifically, as shown in Figure 4, the first connecting wire 63 of the wiring 6 has a plurality of first parts 631 and at least one second part 632. The first parts 631 extend in a first direction (here, the negative Y-axis direction). The second parts 632 extend in a second direction that intersects the first direction (here, the negative Y-axis direction) and connect two adjacent first parts 631 in the first direction.

[0051] In other words, in the above configuration, the first connecting wiring 63 does not extend long in the first direction. To put it another way, in the process of forming the first connecting wiring 63, the dimensions of the recess in a direction perpendicular to the direction of travel of the doctor blade or blanket are relatively small. Therefore, phenomena such as the doctor blade scraping off ink in the recess or the blanket sinking deeply into the recess can be reduced. Accordingly, according to the thermal head X1 of the first embodiment, defects in the wiring 6 can be reduced and the print quality can be improved.

[0052] The length L1 of the first portion 631 in the first direction (here, the negative Y-axis direction) may be 3 mm or less. The width of the first portion 631 may be 100 μm or less.

[0053] The second direction in which the second portion 632 extends may be oblique to the first direction (in this case, the negative Y-axis direction). This makes it less likely for air bubbles to enter the second portion 632 during the formation process of the first connecting wiring 63. Therefore, defects in the wiring 6 can be reduced, and the print quality can be improved.

[0054] When the direction perpendicular to the first direction (here, the positive X-axis direction) is defined as the third direction, in two first parts 631 that are adjacent in the third direction and have overlapping portions when viewed in the third direction, the distance S1 between them in the third direction may be 200 μm or less.

[0055] As a result, in gravure offset printing, when transferring the printing paste filled in the recesses of the gravure plate to the blanket, the recesses are arranged at relatively close intervals in the direction of blanket movement, which reduces excessive sinking of the blanket. Therefore, the possibility of the printing width of the print pattern becoming wider than the design value can be reduced, and the print quality can be improved.

[0056] When the direction opposite to the third direction (here, the positive X-axis direction) is defined as the fourth direction (here, the negative X-axis direction), the multiple first parts 631 in a single first connection wiring 63 may be positioned such that the first part 631 located further towards the first direction (here, the negative Y-axis direction) is positioned further towards the third direction (here, the positive X-axis direction), or the first part 631 located further towards the first direction (here, the negative Y-axis direction) is positioned further towards the fourth direction (here, the negative X-axis direction).

[0057] In other words, multiple first portions 631 in a single first connecting wire 63 may be arranged so as not to overlap with each other in a first direction (here, the negative Y-axis direction). This ensures that in the process of forming the first connecting wire 63, only one recess is located in a direction perpendicular to the direction of travel of the doctor blade or blanket. This reduces the phenomenon of the doctor blade sinking too deeply. It also makes it less likely for air bubbles to enter the recess when the doctor blade passes through it. Therefore, defects in the first connecting wire 63 can be reduced, and the print quality can be improved.

[0058] Figures 5 to 8 are plan views showing another example of the first connecting wiring 63 according to the first embodiment.

[0059] As shown in Figure 5, the thermal head X1 may have a plurality of first connecting portions 633, which are the parts that connect the first portion 631 and the second portion 632. The first connecting portions 633 may have an arc shape. Specifically, in a plan view of the thermal head X1, the first connecting portion 633 between the side surface of the first portion 631 and the side surface of the second portion 632 may have an arc shape. The radius of curvature of the arc in the arc shape of the first connecting portion 633 may be, for example, 5 μm or more.

[0060] The first connection portion 633 has an arc shape, which reduces the impact on the recess of the gravure plate when the doctor blade rubs against it during the formation process of the first connection wiring 63. Therefore, the service life of the gravure plate and the doctor blade can be extended. In addition, the concentration of the electric field at the first connection portion 633 can be reduced. Furthermore, air bubbles are less likely to form during the formation process of the first connection wiring 63, thus reducing irregularities in the wiring shape.

[0061] As shown in Figure 6, the first portion 631 may have a third portion 6311 and a fourth portion 6312.

[0062] The third portion 6311 is a portion whose width increases as it moves toward the first direction (here, the negative Y-axis direction). The fourth portion 6312 is a portion whose width decreases as it moves toward the first direction (here, the negative Y-axis direction). The fourth portion 6312 may be located closer to the first direction (here, the negative Y-axis direction) than the third portion 6311. That is, the first portion 631 may become wider and then narrower as it moves toward the first direction (here, the negative Y-axis direction).

[0063] As a result, in the process of forming the first connecting wiring 63, the recess takes on a shape where the starting end in the direction of blanket movement gradually widens. Therefore, as the blanket is pressed against the recess, the blanket can be gradually pressed tightly against the recess so that the air inside the recess does not escape to the starting end in the direction of blanket movement. In addition, since the recess has a shape where the ending end in the direction of blanket movement gradually narrows, the air inside the recess can be moved in the direction of blanket movement. This reduces the generation of air bubbles. Consequently, it is possible to reduce irregularities in the printing pattern, the occurrence of pinholes and disconnections in the process of forming the first connecting wiring 63, and improve the quality of printing.

[0064] The increase in width in the third part 6311 may be 0.15% or more of the length of the first part 631.

[0065] As shown in Figure 7, multiple first parts 631 may not be located at a single position in the third direction (here, the positive X-axis direction). Specifically, multiple first parts 631 in one first connecting wire 63 may not be located at a single position in the third direction (here, the positive X-axis direction). Also, multiple first parts 631 in multiple first connecting wires 63 may not be located at a single position in the third direction (here, the positive X-axis direction).

[0066] As a result, in the process of forming the first connecting wiring 63, only one recess is located in a direction perpendicular to the direction of travel of the doctor blade or blanket. Therefore, the phenomenon of the doctor blade or blanket sinking too deeply into the recess can be reduced. Consequently, the possibility of defects in the first connecting wiring 63 or the print width of the printed pattern becoming wider than the design value can be reduced, and the print quality can be improved.

[0067] As shown in Figure 8, there are multiple first parts 631A, 631B at one position in the third direction (here, the positive X-axis direction), and the spacing S2 in the first direction between adjacent first parts 631A, 631B at one position in the first direction (here, the negative Y-axis direction) may be 100 μm or more.

[0068] As a result, in the process of forming the first connecting wiring 63, the spacing between two adjacent recesses in a direction perpendicular to the direction of travel of the doctor blade or blanket becomes relatively wide. Therefore, the phenomenon of the doctor blade or blanket sinking too deeply into the recesses can be reduced. Consequently, the possibility of defects in the first connecting wiring 63 or the print width of the printed pattern becoming wider than the design value can be reduced, and the print quality can be improved.

[0069] As shown in Figure 5, the multiple first connection points 633 may be located at different positions in the first direction (here, the negative Y-axis direction). In the example in Figure 5, the first connection point 633A in the first connection wiring 63A and the first connection point 633B in the first connection wiring 63B are located at different positions in the first direction (here, the negative Y-axis direction).

[0070] This reduces the likelihood of the doctor blade repeatedly hitting the corner of the recess in the gravure plate (corresponding to the first connection portion 633) at any given position during the process of forming the first connection wiring 63. Therefore, the doctor blade is less likely to be damaged.

[0071] As described above, in the thermal head X1 according to the first embodiment, the first connecting wiring 63 has a plurality of first parts 631 and at least one second part 632. The first parts 631 extend in a first direction (here, the negative Y-axis direction). The second parts 632 extend in a second direction that intersects the first direction (here, the negative Y-axis direction) and connect two adjacent first parts 631 in the first direction. This reduces phenomena such as the doctor blade scraping ink from recesses or the blanket sinking too deeply into recesses. Therefore, according to the thermal head X1 according to the first embodiment, defects in the wiring 6 can be reduced and the print quality can be improved.

[0072] Although Figure 4 shows an example where the first connecting wire 63 has multiple second parts 632, the number of second parts 632 is not limited to this. The first connecting wire 63 may have only one second part 632.

[0073] Furthermore, although an example is shown here in which the second portion 632 of the first connecting wire 63 extends in a direction oblique to the first direction (here, the negative Y-axis direction), the direction in which the second portion 632 extends is not limited to this. For example, the second portion 632 may extend in a direction perpendicular to the first direction (here, the positive X-axis direction and the negative X-axis direction).

[0074] Furthermore, while examples have been shown here of multiple first parts 631 in a single first connection wiring 63 where the first parts 631 located further towards the first direction (here, the negative Y-axis direction) are located further towards the third direction (here, the positive X-axis direction), and examples where the first parts 631 located further towards the first direction (here, the negative Y-axis direction) are located further towards the fourth direction (here, the negative X-axis direction), the positions of the first parts 631 are not limited to these. For example, a single first connection wiring 63 may have multiple first parts 631 at one position in the third direction (here, the positive X-axis direction). In this case, the spacing in the first direction between adjacent first parts 631 in the first direction (here, the negative Y-axis direction) among the multiple first parts 631 at one position may be 100 μm or more.

[0075] (Second Embodiment) Figure 9 is a plan view showing an example of a first connecting wiring 63 according to the second embodiment. As shown in Figure 9, the first connecting wiring 63 may be branched. Specifically, the first connecting wiring 63 may have a branching point P1, a merging point P2, and a branched portion P3.

[0076] Branch point P1 is the point where one merging wire 634 (an example of wiring) branches into multiple branch wires 635. Merging point P2 is the point where multiple branch wires 635 merge into one merging wire 634. Branch section P3 is located between branch point P1 and merging point P2 and is the section where multiple branch wires 635 extend side by side. In the example in Figure 9, the merging wire 634 of the first connecting wire 63 branches into two branch wires 635.

[0077] As a result, even if one branch wire 635 becomes thinner due to the doctor blade scraping ink from the recess during the formation process of the first connection wire 63, the remaining branch wires 635 can still secure the wiring area, thereby reducing wiring resistance. Furthermore, even if one branch wire 635 is damaged or broken due to the doctor blade scraping ink from the recess or the blanket sinking deeply into the recess, conductivity can be maintained through the remaining branch wires 635. Therefore, according to the thermal head X1 of the second embodiment, the breakage of the first connection wire 63 can be reduced, and the print quality can be improved.

[0078] Figures 10 to 12 are plan views showing another example of the first connecting wiring 63 according to the second embodiment.

[0079] As shown in Figure 10, the branch portion P3 may include a first portion 631. In other words, each of the multiple branch wirings 635 may have a first portion 631 extending in a first direction (here, the negative Y-axis direction). As described above, when the first direction is perpendicular to the direction of travel of the doctor blade or blanket, the doctor blade is likely to scrape the ink in the recess corresponding to the first portion 631 or the blanket may sink deeply into the recess during the formation process of the first connecting wiring 63. In the first connecting wiring 63 according to the second embodiment, since the first portion 631 is included in the branch portion P3, even if one branch wiring 635 is missing or broken, conductivity can be maintained in all the remaining branch wirings 635. Therefore, the breakage of the first connecting wiring 63 can be reduced, and the print quality can be improved.

[0080] As shown in Figure 10, the first connecting wire 63 may have a fifth section 636 that connects multiple branch wires 635 in the branch section P3. In other words, the first connecting wire 63 may have a fifth section 636 that connects two adjacent branch wires 635. This allows the fifth section 636 to branch into multiple branch wires 635 even if a break occurs in part of one branch wire 635, thus shortening the length of the section affected by the break. Therefore, the increase in wiring resistance when a break occurs in part of one branch wire 635 can be reduced.

[0081] The fifth part 636 may extend, for example, in a third direction (in this case, the positive X-axis direction) perpendicular to the first direction.

[0082] As shown in Figure 10, the branch section P3 may include a second section 632. In other words, each of the two branch wirings 635 may have a second section 632 extending in a second direction oblique to the first direction. In this case, the fifth section 636 may connect the second sections 632 of multiple branch wirings 635 of the branch section P3. In other words, the fifth section 636 may connect the second sections 632 of two adjacent branch wirings 635 in the first connecting wiring 63.

[0083] Thus, in the process of forming the first connecting wiring 63, the recesses corresponding to the branch wiring 635 connect at points that extend in a direction inclined with respect to the direction perpendicular to the direction of travel of the doctor blade, allowing the ink in the recesses to move fluidly to the fifth portion 636. Therefore, the loss of the fifth portion 636 in the first connecting wiring 63 can be reduced, and the print quality can be improved.

[0084] As shown in Figure 10, the first connecting wire 63 may have multiple fifth portions 636. In this case, the spacing S3 in the first direction between two adjacent fifth portions 636 in the first direction (here, the negative Y-axis direction) may be 100 μm or more.

[0085] As a result, in the process of forming the first connecting wiring 63, the spacing between two adjacent recesses in a direction perpendicular to the direction of travel of the doctor blade or blanket becomes relatively wide. Therefore, the phenomenon of the doctor blade or blanket sinking too deeply into the recesses can be reduced. Consequently, the possibility of defects in the first connecting wiring 63 or the print width of the printed pattern becoming wider than the design value can be reduced, and the print quality can be improved.

[0086] The spacing S4 (see Figure 11) between multiple branch wirings 635 in the branch section P3 in the third direction (here, the positive X-axis direction) may be 200 μm or less. In other words, the spacing S4 between two adjacent branch wirings 635 in the first connecting wiring 63 in the third direction may be 200 μm or less.

[0087] As a result, in gravure offset printing, when transferring the printing paste filled in the recesses of the gravure plate to the blanket, the recesses are arranged at relatively close intervals in the direction of blanket movement, which reduces excessive sinking of the blanket. Therefore, the possibility of the printing width of the print pattern becoming wider than the design value can be reduced, and the print quality can be improved.

[0088] As shown in Figure 11, the thermal head X1 has a second connection portion 637, which is the portion where the multiple branch wirings 635 of the branch portion P3 and the fifth portion 636 are connected. The second connection portion 637 may have an arc shape. Specifically, in a plan view of the thermal head X1, the second connection portion 637 between the side surface of the second portion 632 of the branch wiring 635 and the side surface of the fifth portion 636 may have an arc shape. The radius of curvature of the arc in the arc shape of the second connection portion 637 may be, for example, 5 μm or more.

[0089] The arc shape of the second connection portion 637 reduces the impact on the recess of the gravure plate when the doctor blade rubs against it during the formation process of the first connection wiring 63. Therefore, the service life of the gravure plate and the doctor blade can be extended. In addition, the concentration of the electric field at the second connection portion 637 can be reduced. Furthermore, air bubbles are less likely to enter during the formation process of the first connection wiring 63, thus reducing irregularities in the wiring shape.

[0090] As shown in Figure 12, the first connecting wire 63 has two ends 63a and 63b, and one of the two ends 63a may branch into a first wire 638 and a second wire 639. The first wire 638 and the second wire 639 may each be connected to different drive ICs 8.

[0091] This reduces the difference in wiring resistance between the first wiring 638 and the second wiring 639. Furthermore, the branching of the first connecting wiring 63 into two branch wirings 635 reduces the wiring resistance between the first wiring 638 and the second wiring 639. Therefore, the difference in operation between the two drive ICs 8 can be reduced, thereby reducing malfunctions.

[0092] In this example, the first connecting wiring 63 has two branch wirings 635, but the number of branch wirings 635 is not limited to this. The first connecting wiring 63 may have, for example, three or more branch wirings 635.

[0093] (Third embodiment) Figure 9 of the second embodiment shows an example in which the branch wiring 635 of the first connecting wiring 63 extends in a stepped manner along the first direction (here, the negative Y-axis direction), but the branch wiring 635 is not limited to this. Figure 13 is a plan view showing an example of the first connecting wiring 63 according to the third embodiment.

[0094] The branch wiring 635 of the first connecting wiring 63 does not have to extend in a stepped manner along the first direction (here, the negative Y-axis direction). For example, as shown in Figure 13, the branch wiring 635A in the branch portion P3 may have only the first portion 631 that extends in the first direction (here, the negative Y-axis direction).

[0095] In this case as well, since the first connecting wire 63 is branched, even if one branched wire 635 becomes thinner due to the doctor blade scraping off ink in the recess during the formation process of the first connecting wire 63, the remaining branched wires 635 can secure the wiring area and reduce the wiring resistance. Furthermore, even if one branched wire 635 is damaged or broken due to the doctor blade scraping off ink in the recess or the blanket sinking deeply into the recess, conductivity can be maintained through all the remaining branched wires 635. Therefore, according to the thermal head X1 of the third embodiment, the breakage of the first connecting wire 63 can be reduced, and the print quality can be improved.

[0096] (Manufacturing method for thermal heads) Next, a method for manufacturing the thermal head X1 according to the first embodiment, the second embodiment, or the third embodiment will be described with reference to Figure 3.

[0097] First, there is the process of forming the heat storage layer 13. Specifically, a paste-like glaze material mainly composed of glass is deposited on the first surface 5a of the substrate 5 and fired. This forms a low, mountain-shaped heat storage layer 13.

[0098] Next is the process of forming the wiring 6. For example, the wiring 6 is formed on the first surface 5a of the substrate 5 on which the heat storage layer 13 is formed using gravure offset printing. The method for forming the wiring pattern by gravure offset printing is as follows: First, printing paste is filled into the recesses of the gravure plate with a doctor blade. Next, the printing paste is transferred to a blanket. Next, the printing paste transferred to the blanket is transferred to the object to be printed, such as a substrate. Finally, the wiring pattern is formed by firing the printing paste. As a result, the wiring 6 is formed on the first surface 5a of the substrate 5 on which the heat storage layer 13 is formed.

[0099] Next is the process of forming the resistor layer 9. Specifically, examples of materials for the resistor layer 9 include TaN-based, TaSiO-based, TaSiNO-based, TiSiO-based, TiSiCO-based, NbSiO-based, or RuO2-based materials, and it is formed on the upper surface of the heat storage layer 13 and the upper surface of the wiring 6 (lead portion 61c of the common wiring 61 and individual wiring 62) by sputtering, screen printing, or dispensing equipment.

[0100] Next is the process of forming the protective layer 11 and the coating layer 12. Specifically, a glass paste for the protective layer is attached to the first surface 5a of the substrate 5 on which the resistor layer 9 and wiring 6 are formed by screen printing or the like. Then, the glass paste is solidified by firing. The protective layer 11 may have a structure of two or more layers, and in order to improve the durability of the head base 3 against sliding of the recording medium, for example, SiN, SiO, SiON, SiC, SiCN, or diamond-like carbon may be formed on the upper surface where the glass paste has been solidified. Subsequently, a resin material such as epoxy resin, polyimide resin, or silicone resin is applied and cured on the upper surface of the protective layer 11 to form the coating layer 12.

[0101] (Thermal printer configuration) Next, a thermal printer Z1 having a thermal head X1 according to the first embodiment, second embodiment, or third embodiment will be described with reference to Figure 14. Figure 14 is a schematic diagram of the thermal printer Z1 according to the first embodiment, second embodiment, or third embodiment.

[0102] The thermal printer Z1 comprises a thermal head X1 according to the first, second, or third embodiment, a transport mechanism 40, a platen roller 50, a power supply unit 60, and a control device 70. The thermal head X1 is mounted on the mounting surface 80a of a mounting member 80 located on the housing (not shown) of the thermal printer Z1. The thermal head X1 is mounted on the mounting member 80 so as to be aligned with the main scanning direction, which is perpendicular to the transport direction S. The thermal printer Z1 is an example of a recording device.

[0103] The transport mechanism 40 includes a drive unit (not shown) and transport rollers 43, 45, 47, and 49. The transport mechanism 40 transports the recording medium P, such as thermal paper or image receiving paper onto which ink is transferred, along the transport direction S indicated by the arrow onto the protective layer 11 located on the multiple heating elements 9a of the thermal head X1. The drive unit has the function of driving the transport rollers 43, 45, 47, and 49. For example, a motor may be used as the drive unit. The transport rollers 43, 45, 47, and 49 may be constructed by covering cylindrical shafts 43a, 45a, 47a, and 49a made of a metal such as stainless steel with elastic members 43b, 45b, 47b, and 49b made of a material such as butadiene rubber. When the recording medium P is image receiving paper onto which ink is transferred, an ink film (not shown) is transported together with the recording medium P between the recording medium P and the heating elements 9a of the thermal head X1. The transport mechanism 40 is an example of a moving part that moves the thermal head X1 and the recording medium P relative to each other.

[0104] The platen roller 50 has the function of pressing the recording medium P onto the protective layer 11 located on the heating element 9a of the thermal head X1. The platen roller 50 is arranged to extend in a direction perpendicular to the transport direction S, and both ends are supported and fixed so that it can rotate while pressing the recording medium P onto the heating element 9a. The platen roller 50 may be constructed, for example, by covering a cylindrical metal shaft 50a, such as stainless steel, with an elastic member 50b made of butadiene rubber or the like.

[0105] The power supply unit 60 has the function of supplying current to generate heat in the heat-generating part 9a of the thermal head X1 and current to operate the drive IC 8, as described above. The control device 70 has the function of supplying a control signal to the drive IC 8 to control the operation of the drive IC 8 in order to selectively generate heat in the heat-generating part 9a of the thermal head X1, as described above.

[0106] The thermal printer Z1 presses the recording medium P onto the heating element 9a of the thermal head X1 using the platen roller 50, and transports the recording medium P onto the heating element 9a using the transport mechanism 40, while selectively heating the heating element 9a using the power supply unit 60 and the control unit 70. As a result, the thermal printer Z1 prints a predetermined image onto the recording medium P. If the recording medium P is such as image receiving paper, the image is printed onto the recording medium P by thermally transferring the ink from an ink film (not shown) transported together with the recording medium P to the recording medium P.

[0107] Furthermore, this technology can also be configured as follows. (1) It has a plurality of heating elements arranged in a first direction and at least one wiring, The wiring comprises a plurality of first parts and at least one second part. The first portion extends in the first direction, A thermal head wherein the second portion extends in a second direction intersecting the first direction and connects two adjacent first portions in the first direction. (2) The thermal head according to (1), wherein the second direction is oblique to the first direction. (3) It has multiple first connecting parts, which are the parts that connect the first part and the second part. The plurality of first connecting portions are arc-shaped, as described in (1) or (2). (4) The thermal head according to any one of (1) to (3), wherein the length of each of the first parts in the first direction is 3 mm or less. (5) A thermal head according to any one of (1) to (4), wherein, when the direction perpendicular to the first direction is taken as the third direction, the distance between two first parts that are adjacent in the third direction and overlap when viewed in the third direction is 200 μm or less. (6) The aforementioned first part comprises a third part and a fourth part, The third portion is a portion whose width increases as it moves toward the first direction, The fourth portion is a portion whose width decreases as it moves toward the first direction, The fourth portion is located on the first side of the third portion, as described in (1). (7) A thermal head according to any one of (1) to (6), wherein, when the direction perpendicular to the first direction is taken as the third direction, and the direction opposite to the third direction is taken as the fourth direction, the plurality of first parts in one wiring are positioned such that the first part that is positioned further towards the first direction is positioned further towards the third direction, or the first part that is positioned further towards the first direction is positioned further towards the fourth direction. (8) A thermal head according to any one of (1) to (7), wherein, when the direction perpendicular to the first direction is defined as the third direction, there are no multiple first parts located at a single position in the third direction. (9) A thermal head according to any one of (1) to (7), wherein, when the direction perpendicular to the first direction is defined as the third direction, there are a plurality of first parts at one position in the third direction, and the distance in the first direction between adjacent first parts at that one position is 100 μm or more. (10) It has multiple first connecting parts, which are the parts that connect the first part and the second part. The thermal head according to any one of (1) to (9), wherein the plurality of first connection portions are located at mutually different positions in the first direction. (11) The thermal head according to any one of (1) to (10), wherein the wiring comprises a branching point which is the point where one wire branches into multiple branching wires, a confluence point which is the point where the multiple branching wires merge into one, and a branching portion which is located between the branching point and the confluence point and where the multiple branching wires extend in parallel. (12) The branch portion includes the first portion, as described in (11). (13) The thermal head according to (11) or (12), further comprising a fifth portion for connecting the plurality of branch wirings in the branch portion. (14) The second direction is oblique to the first direction, The aforementioned branch portion includes the aforementioned second portion, The fifth part is the thermal head according to (13), wherein the second parts in the plurality of branch wirings of the branch section are connected to each other. (15) Having multiple of the aforementioned fifth parts, The thermal head according to (13) or (14), wherein the distance in the first direction between two adjacent fifth portions is 100 μm or more. (16) The thermal head according to any one of (11) to (15), wherein, when the direction perpendicular to the first direction is defined as the third direction, the spacing between the plurality of branch wirings in the branch portion in the third direction is 200 μm or less. (17) The branch section has a second connection section which is the part where the plurality of branch wirings of the branch section are connected to the fifth section. The second connecting portion is a thermal head according to any one of (13) to (15), having an arc shape. (18) It has multiple drive ICs, The thermal head according to any one of (11) to (17), wherein the wiring has two ends, one of which branches into a first wiring and a second wiring, and the first wiring and the second wiring are each connected to different drive ICs. (19) A thermal head as described in any one of (1) to (18), A moving unit that moves the thermal head and the recording medium relative to each other, A recording device having the following features. (20) A step of forming a resistor layer extending in a first direction, A process of forming at least one wiring by gravure offset printing, Includes, The wiring comprises a plurality of first parts and at least one second part. The first portion extends in the first direction, A method for manufacturing a thermal head, wherein the second portion extends in a second direction intersecting the first direction and connects two adjacent first portions in the first direction.

[0108] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Indeed, the embodiments described above can be embodied in a variety of forms. Furthermore, the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of Symbols]

[0109] 5 circuit boards 6 Wiring 61c Lead section 8 Drive ICs 9 Resistor layer 9a Heat-generating part 10 Covering member 11 Protective layer 12 Covering layer 13 Heat storage layer 40 Conveying mechanism 61 Common Wiring 62 Individual wiring 63 First connection wiring 64 Second connection wiring 631 Part 1 632 Part 2 633 First connection section 635 Branch wiring 636 Part 5 637 Second connection section 638 1st wiring 639 2nd wiring 6311 Part 3 6312 Part 4 P recording medium P1 Junction P2 confluence P3 branching section X1 Thermal Head Z1 Thermal Printer

Claims

1. It has a plurality of heating elements arranged in a first direction and at least one wiring, The aforementioned wiring has a plurality of first parts and at least one second part, The first portion extends in the first direction and has a third portion and a fourth portion. The second portion extends in a second direction intersecting the first direction, and connects two adjacent first portions in the first direction. The third portion is a portion whose width increases as it moves toward the first direction, The fourth portion is a portion whose width decreases as it moves toward the first direction, The fourth portion is a thermal head located on the first side of the third portion.

2. The thermal head according to claim 1, wherein the second direction is oblique to the first direction.

3. It has multiple first connecting parts, which are the parts that connect the first part and the second part. The thermal head according to claim 1, wherein the plurality of first connection portions have an arc shape.

4. The thermal head according to claim 1, wherein the length of each of the first portions in the first direction is 3 mm or less.

5. The thermal head according to claim 1, wherein, when the direction perpendicular to the first direction is defined as the third direction, the distance between two first portions that are adjacent in the third direction and overlap when viewed in the third direction is 200 μm or less.

6. The thermal head according to claim 1, wherein when the direction perpendicular to the first direction is defined as the third direction, and the direction opposite to the third direction is defined as the fourth direction, the plurality of first portions in one wiring are positioned such that the first portion that is positioned further towards the first direction is positioned further towards the third direction, or the first portion that is positioned further towards the first direction is positioned further towards the fourth direction.

7. The thermal head according to claim 1, wherein, when the direction perpendicular to the first direction is defined as the third direction, there are no multiple first portions located at any single position in the third direction.

8. The thermal head according to claim 1, wherein, when the direction perpendicular to the first direction is defined as the third direction, there are a plurality of first parts at one position in the third direction, and the distance between adjacent first parts in the first direction at the plurality of first parts at one position is 100 μm or more.

9. It has multiple first connecting parts, which are the parts that connect the first part and the second part. The thermal head according to claim 1, wherein the plurality of first connection portions are located at mutually different positions in the first direction.

10. Having a plurality of heating elements arranged in a first direction and at least one wiring, The aforementioned wiring has a plurality of first parts and at least one second part, The first portion extends in the first direction, The second portion extends in a second direction intersecting the first direction, and connects two adjacent first portions in the first direction. The wiring comprises a branching point where one wire branches into multiple branch wires, a merging point where the multiple branch wires merge into one, and a branching portion located between the branching point and the merging point where the multiple branch wires extend side by side, in a thermal head.

11. The thermal head according to claim 10, wherein the branch portion includes the first portion.

12. The thermal head according to claim 10, further comprising a fifth portion for connecting the plurality of branch wirings in the branch portion.

13. The second direction is oblique to the first direction, The aforementioned branch portion includes the second portion, The thermal head according to claim 12, wherein the fifth portion connects the second portions of the plurality of branch wirings of the branch portion.

14. Having multiple of the aforementioned fifth parts, The thermal head according to claim 12, wherein the distance in the first direction between two adjacent fifth portions is 100 μm or more.

15. The thermal head according to claim 10, wherein when the direction perpendicular to the first direction is defined as the third direction, the spacing between the plurality of branch wirings in the branch portion in the third direction is 200 μm or less.

16. The branch section has a second connection section which is the part where the plurality of branch wirings of the branch section are connected to the fifth section. The thermal head according to claim 12, wherein the second connecting portion has an arc shape.

17. It has multiple driver ICs, The thermal head according to claim 10, wherein the wiring has two ends, one of which branches into a first wiring and a second wiring, and the first wiring and the second wiring are each connected to different drive ICs.

18. A thermal head according to any one of claims 1 to 17, A moving unit that moves the thermal head and the recording medium relative to each other, A recording device having the following features.

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