Thermal head and printer

Abstract

A thermal head according to an aspect of the present invention comprises: a plurality of heating elements arranged in the main scanning direction; a driving circuit that is provided in parallel with the plurality of heating elements in the main scanning direction and that selectively causes the plurality of heating elements to generate heat; an electronic circuit having wiring for supplying a signal to the driving circuit and a signal ground; and a belt-like conductor provided closer to the driving circuit side as compared to the plurality of heating elements in the sub-scanning direction and disposed in parallel with the plurality of heating elements in the main scanning direction. The belt-like conductor is electrically connected to the signal ground.

Description

Thermal head, printer

[0001] The present invention relates to a thermal head that is mounted in a printer to perform printing.

[0002] When a thermal head is installed in a printer, it is positioned so that it and a platen roller sandwich a print medium such as a label. The thermal head is equipped with multiple heating elements, and is configured to print on the print medium by selectively activating the heating elements. However, since the print medium and the ink ribbon used for thermal transfer can become charged as they are transported through the printer, various proposals have been made to prevent damage to the thermal head due to static electricity discharge from the print medium and the ink ribbon.

[0003] For example, Japanese Patent Application Laid-Open No. 8-150747 describes a thermal head in which a conductive member that contacts the thermal recording medium is provided upstream of the heating resistor in the transport direction of the thermal recording medium, and is connected to a cover member or a heat sink and grounded.

[0004] In the conventional thermal head described above, the cover member connected to the conductive member is fastened to the heat sink with metal screws, which makes it difficult to stably transfer electric charges through the cover member, or through the cover member and heat sink, due to variations in electrical resistance caused by the mechanical contact of the screws.

[0005] Therefore, an object of one aspect of the present invention is to more effectively prevent damage to a thermal head due to electrostatic discharge.

[0006] One aspect of the present invention is a thermal head comprising: a plurality of heating elements arranged in a main scanning direction; a drive circuit section arranged in parallel to the plurality of heating elements along the main scanning direction and causing the plurality of heating elements to selectively generate heat; an electronic circuit section having wiring that supplies signals to the drive circuit section and a signal ground; and a band-shaped conductor arranged closer to the drive circuit section than the plurality of heating elements in the sub-scanning direction and arranged in parallel to the plurality of heating elements along the main scanning direction, wherein the band-shaped conductor is electrically connected to the signal ground.

[0007] According to one aspect of the present invention, damage to the thermal head due to electrostatic discharge can be more effectively prevented.

[0008] 3 is a diagram illustrating a state in which a thermal head according to an embodiment is used. FIG. 4 is a perspective view of a thermal head according to an embodiment. FIG. 5 is a bottom view and a plan view of the thermal head shown in FIG. 2. FIG. 6 is an enlarged view of the X-X cross section of FIG. 3. FIG. 7 is a perspective view of a thermal head according to an embodiment different from that shown in FIG. 2. FIG. 8 is a perspective view of a thermal head according to an embodiment different from that shown in FIG. 2.

[0009] The embodiments described below are not limited to the drawings described in the brief description of the drawings. In the following description, for convenience of explanation, the term "printing medium" may refer not only to an object to be printed (e.g., a label) but also to a combination of an ink ribbon and a receiving object (e.g., a label) to which the ink of the ink ribbon is transferred.

[0010] A first aspect of the present invention is a thermal head comprising: a plurality of heating elements arranged in a main scanning direction; a drive circuit section arranged in parallel to the plurality of heating elements along the main scanning direction and causing the plurality of heating elements to selectively generate heat; an electronic circuit section having wiring for supplying signals to the drive circuit section and a signal ground; and a strip-shaped conductor arranged closer to the drive circuit section than the plurality of heating elements in the sub-scanning direction and arranged in parallel to the plurality of heating elements along the main scanning direction, wherein the strip-shaped conductor is electrically connected to the signal ground.

[0011] According to a first aspect of the present invention, damage to the thermal head due to electrostatic discharge can be more effectively prevented.

[0012] A second aspect of the present invention is a thermal head described in the first aspect, in which the band-shaped conductor is located at a position farther from the multiple heating elements in the sub-scanning direction than the drive circuit unit.

[0013] According to a second aspect of a certain aspect of the present invention, when the printing medium being printed on by multiple heating elements is charged, the printing medium can be de-electrified upstream of the drive circuit unit in the transport direction, thereby effectively protecting the drive circuit unit.

[0014] A third aspect of the present invention is a thermal head described in the first or second aspect, in which the length of the band-shaped conductor in the main scanning direction is the same as the length of the multiple heating elements in the main scanning direction, or is longer than the length of the multiple heating elements.

[0015] According to a third aspect of the present invention, it is possible to effectively protect a plurality of heating elements extending in the main scanning direction from static electricity.

[0016] A fourth aspect of the present invention is a thermal head described in any one of the first to third aspects, in which the band-shaped conductor is electrically connected to the signal ground via the shortest path from at least one of one end and the other end in the longitudinal direction.

[0017] According to the fourth aspect of the present invention, electricity can be removed from the strip-shaped conductor via the shortest path, so that damage that may be caused by static electricity to the drive circuit section and electronic circuit section can be minimized.

[0018] A fifth aspect of the present invention is the thermal head according to any one of the first to fourth aspects, further comprising a protective film covering the plurality of heating elements.

[0019] According to a fifth aspect of the present invention, even when a plurality of heating elements are covered with a protective film, it is possible to prevent damage such as pinholes from occurring in the protective film due to static electricity.

[0020] A sixth aspect of the present invention is a thermal head described in any one of the first to fifth aspects, in which the strip-shaped conductor is electrically connected directly to the signal ground via a conductive member.

[0021] According to a sixth aspect of the present invention, the static electricity can be stably removed by the strip-shaped conductor and the conductive member.

[0022] A seventh aspect of the present invention is a thermal head according to the sixth aspect, in which the conductive member is arranged along the surface of the thermal head on which the multiple heating elements are provided.

[0023] According to a seventh aspect of the present invention, since the conductive member is arranged on the same surface as the multiple heating elements, damage to the multiple heating elements due to electrostatic discharge can be more effectively prevented.

[0024] An eighth aspect of the present invention is a thermal head described in the seventh aspect, comprising a rigid substrate on which the multiple heating elements and the drive circuit unit are arranged, and a flexible substrate on which the electronic circuit unit is arranged, and the conductive member is arranged along the substrate surface of the rigid substrate and / or the flexible substrate.

[0025] According to an eighth aspect of a certain aspect of the present invention, a conductive member is arranged on the same surface as multiple heating elements, drive circuit units, or electronic circuit units, thereby effectively suppressing damage caused by electrostatic discharge to multiple heating elements, drive circuit units, or electronic circuit units.

[0026] A ninth aspect of the present invention is the thermal head according to any one of the sixth to eighth aspects, wherein the conductive member is a conductive tape.

[0027] According to a ninth aspect of the present invention, the workability when electrically connecting the strip-shaped conductor and the signal ground is improved.

[0028] A tenth aspect of the present invention is a thermal head described in any one of the sixth to eighth aspects, in which the conductive member is a jumper wire soldered to the strip-shaped conductor and the signal ground.

[0029] According to a tenth aspect of the present invention, the electrical connection between the strip-shaped conductor and the signal ground can be more reliably established.

[0030] An eleventh aspect of the present invention is a thermal head described in any one of the sixth to eighth aspects, in which the conductive member is a flexible substrate on which a predetermined conductive pattern is formed, and the conductive pattern is electrically connected to the signal ground.

[0031] According to an eleventh aspect of the present invention, it is possible to suppress the influence on the drive circuit section and the electronic circuit section when static electricity is released from the band-shaped conductor to the signal ground.

[0032] A twelfth aspect of the present invention is a thermal head described in any one of the first to fifth aspects, which is provided with a conductive heat dissipation portion that dissipates heat generated by the thermal head, and the band-shaped conductor is electrically connected to the signal ground via the heat dissipation portion.

[0033] According to a twelfth aspect of the present invention, the heat dissipation portion can be used when electrically connecting the strip-shaped conductor and the signal ground.

[0034] A thirteenth aspect of the present invention is a thermal head described in the twelfth aspect, in which the band-shaped conductor is electrically connected to the heat dissipation portion via a first conductive member, and the signal ground is electrically connected to the heat dissipation portion via a second conductive member.

[0035] According to a thirteenth aspect of the present invention, the strip-shaped conductor and the signal ground can be electrically connected simply by attaching the first conductive member and the second conductive member to the heat dissipation portion.

[0036] A fourteenth aspect of the present invention is the thermal head according to any one of the first to thirteenth aspects, wherein the strip-shaped conductor is copper foil.

[0037] According to a fourteenth aspect of the present invention, by using copper foil having excellent conductivity as the strip-shaped conductor, static electricity can be effectively removed.

[0038] A fifteenth aspect of the present invention is a printer comprising: a thermal head described in any one of the first to fourteenth aspects; and a control board having a ground terminal and connected to the thermal head via a connector, wherein the signal ground and the ground terminal are electrically connected via the connector.

[0039] According to a fifteenth aspect of the present invention, damage to a thermal head mounted in a printer due to electrostatic discharge can be more effectively prevented.

[0040] A thermal head according to an embodiment will be described below with reference to the drawings. First, the environment in which the thermal head is used will be described with reference to Fig. 1. Fig. 1 is a diagram for explaining the usage state of a thermal head 1 according to an embodiment, showing the thermal head 1 mounted in a printer.

[0041] As shown in Figure 1, when the thermal head 1 is installed in a printer, the print medium PM is sandwiched between the heat generating portion 6 of the thermal head 1 and the platen roller 9, and printing is performed while the print medium PM is transported in the transport direction D1 by the rotation of the platen roller 9. The print medium PM includes a label PL, such as plain paper, and an ink ribbon RB for thermal transfer. The print medium PM may not include the ink ribbon RB, in which case the print medium PM may simply be a label (e.g., thermal paper) with a thermosensitive coloring layer formed thereon. Note that in the example shown in Figure 1, the sub-scanning direction Ds of the thermal head 1 coincides with the transport direction D1 of the label PL at the heat generating portion 6.

[0042] As described below, the heating unit 6 includes multiple heating elements (heating resistors) arranged in the main scanning direction. The thermal head 1 prints on the label PL by selectively activating the multiple heating elements. Because the print medium PM becomes charged as it is transported, electrostatic discharge can occur from the print medium PM as the charged portion of the print medium PM approaches the thermal head 1. As shown in FIG. 1 , the distance between the print medium PM and the thermal head 1 decreases as the print medium PM approaches the heating unit 6 of the thermal head 1. Therefore, to more effectively protect the heating unit 6 and the electronic circuits connected to the heating unit 6 from electrostatic discharge, it is necessary to remove (dissipate) static electricity SE as far upstream as possible from the heating unit 6 in the transport direction (i.e., before static electricity from the print medium PM adversely affects the heating unit 6 and the electronic circuits). Therefore, as described below, the thermal head 1 forms a discharge path to dissipate static electricity SE upstream of the heating unit 6 in the transport direction D1.

[0043] Next, a specific configuration of the thermal head 1 of one embodiment will be described with reference to Figures 2 to 4. Figure 2 is a perspective view of the thermal head 1 of one embodiment. Figure 3 is a bottom view and a plan view of the thermal head 1 shown in Figure 2. Figure 4 is an enlarged view of the X-X cross section of Figure 3.

[0044] The thermal head 1 includes a head substrate 2, an FPC (Flexible Printed Circuit) 4, a heat dissipation unit 5, and a connector 18. The head substrate 2 is located on the heat dissipation unit 5. The FPC 4 is electrically connected to the head substrate 2. The head substrate 2 includes a rigid substrate 3, a heat generating unit 6, and a drive circuit unit 7 (an example of a drive circuit unit). The rigid substrate 3 is plate-shaped and made of an electrically insulating material such as alumina ceramics or a semiconductor material such as single crystal silicon. The heat generating unit 6 and the drive circuit unit 7 are mounted on a main surface 3a (an example of a substrate surface) of the rigid substrate 3.

[0045] The heat generating unit 6 includes a plurality of heat generating elements 6a (see FIG. 4; an example of a heat generating element) arranged in the main scanning direction Dp for printing. The drive circuit unit 7 includes a plurality of drive ICs 71 arranged in parallel with the heat generating unit 6 along the main scanning direction Dp. Each drive IC 71 is an integrated circuit made up of switching elements for selectively generating heat in the plurality of heat generating elements. Each of the plurality of drive ICs 71 is electrically connected to, for example, a predetermined number of heat generating elements 6a in the main scanning direction Dp.

[0046] The FPC 4 is connected to the rigid substrate 3 and is provided on the heat dissipation portion 5 so as to conform to the shape of the heat dissipation portion 5. This results in the formation of stepped main surfaces 4a and 4b (each an example of a substrate surface) on the FPC 4. A connector 18 is attached to the main surface 4b of the FPC 4 with solder 91 (see FIG. 3 ). The FPC 4 includes an electronic circuit section 81 (an example of an electronic circuit section) and a signal ground 82. As shown in FIG. 3 , the signal ground 82 is exposed on the main surface 4b of the FPC 4. The electronic circuit section 81 includes a wiring pattern on which wiring is formed that supplies signals input from terminals (not shown) of the connector 18 to the drive circuit section 7. The electronic circuit section 81 may also include electronic components such as a memory and a thermistor. As shown in FIG. 4 , the electronic circuit section 81 is formed on a substrate 83, which is an insulating film.

[0047] When the thermal head 1 is attached to the printer, the connector 18 is connected to a connector (not shown) of the printer, thereby electrically connecting the thermal head 1 to the printer's control board. The signals input from the printer's control board to the thermal head 1 are, but are not limited to, control signals for printing, such as data signals and strobe signals.

[0048] The signal ground 82 is a circuit pattern (a circuit pattern used as a signal feedback path) to which a potential that serves as a reference for the operation of the electronic circuit included in the electronic circuit unit 81 is applied. The signal ground 82 is also called a ground terminal or a ground pad. The signal ground 82 is formed and exposed on the side of the substrate 83 opposite to the side on which the electronic circuit unit 81 is formed. The electronic circuit unit 81 and the signal ground 82 are electrically connected by, for example, a through-hole formed in the substrate 83.

[0049] The heat dissipation section 5 is formed in a plate shape and is made of a metal material with relatively high conductivity, such as copper, iron, aluminum, etc. The heat dissipation section 5 is provided to dissipate to the outside of the thermal head 1 the heat (Joule heat) generated in the heat generating section 6 of the head base 2 that does not contribute to printing.

[0050] 4, the protective film 62 is formed on the main surface 3a of the rigid substrate 3 so as to cover the heating element 6a. The protective film 62 has insulating properties and is formed to protect the heating element 6a. The protective film 62 is made of, for example, SiN or SiO ２ The protective film 62 can be fabricated using thin-film formation techniques such as sputtering using materials such as TiN, CrN, and DLC (Diamond-Like Carbon). While a thicker protective film improves the durability of the heating elements 6a, it is prone to bleeding and tailing of prints, making a thinner protective film preferable from the standpoint of print performance. When the protective film 62 is thin, it is formed by sputtering or metal vapor deposition, while when it is thick, it is formed by screen printing. The individual electrodes 61 electrically connect each heating element 6a to the driving IC 71. One end of each individual electrode 61 in the sub-scanning direction Ds is connected to the heating element 6a, and the other end of each individual electrode 61 is connected to the driving IC 71 via a conductive adhesive 74. Although not shown, a common electrode is formed on the main surface 3a of the rigid substrate 3.

[0051] The driving IC 71 is covered with a covering member 72. The covering member 72 is made of, for example, epoxy resin or silicone resin. As shown in FIGS. 2 and 3 , the covering member 72 covers the entire driving circuit unit 7 along the main scanning direction Dp. The signal electrodes 73 extend from the driving IC 71 toward the FPC 4 along the sub-scanning direction Ds. One end of the signal electrode 73 is connected to the driving IC 71 via a conductive adhesive 74, and the other end of the signal electrode 73 is electrically connected via a conductive adhesive 75 to a wiring pattern included in the electronic circuit unit 81 in the FPC 4. The individual electrodes 61 and the signal electrodes 73 can be fabricated by, for example, screen printing, or by forming a thin film by sputtering or the like and then processing it into a predetermined pattern by photoetching.

[0052] Referring to FIG. 2, a strip-shaped conductor 10 is arranged on the main surface 4a of the FPC 4 in parallel with the heat generating portion 6 along the main scanning direction Dp. The strip-shaped conductor 10 is provided to protect the thermal head 1 from electrostatic discharge from the print medium. Note that in FIG. 3, the strip-shaped conductor 10 is shown by an imaginary line. The strip-shaped conductor 10 is, for example, copper foil or copper foil tape, but is not limited thereto and may also be a highly conductive metal foil or metal tape such as aluminum or iron. The strip-shaped conductor 10 is attached to the main surface 4a of the FPC 4 via, for example, a conductive adhesive.

[0053] As shown in FIG. 2 , in the thermal head 1, a conductive tape 11 is adhered between the strip-shaped conductor 10 and the signal ground 82, thereby electrically connecting the strip-shaped conductor 10 and the signal ground 82. The conductive tape 11 is a highly conductive metal tape, such as copper, aluminum, or iron. By providing the conductive tape 11, a discharge path is formed from the strip-shaped conductor 10 to the conductive tape 11 to the signal ground 82 in response to static electricity from the print medium, thereby protecting the thermal head 1 from electrostatic discharge. Furthermore, unlike conductive adhesives that require a certain curing time, the use of the conductive tape 11 allows the adhesive portion of the conductive tape 11 to quickly bond the conductive tape 11 to the strip-shaped conductor 10 and the signal ground 82, which is advantageous in terms of work efficiency.

[0054] 2 and 3 , the signal ground 82 is formed on the main surface 4b of the FPC 4 near the end in the main scanning direction Dp. The conductive tape 11 starts at the end 10e of the strip-shaped conductor 10 arranged in the main scanning direction Dp, which is closer to the signal ground 82, and extends to the signal ground 82. That is, the strip-shaped conductor 10 is electrically connected to the signal ground 82 via the shortest path from at least one of its ends in the longitudinal direction (the direction that coincides with the main scanning direction Dp in this example). This allows electricity to be removed from the strip-shaped conductor 10 via the shortest path, minimizing damage that static electricity can cause to the drive circuit unit 7 and the electronic circuit unit 81.

[0055] In one embodiment, the strip-shaped conductor 10 is provided closer to the drive circuit unit 7 than the heat generating unit 6 in the sub-scanning direction Ds. This allows charge due to electrostatic discharge from the print medium PM to escape upstream in the transport direction D1 when the thermal head 1 is mounted on a printer, as shown in FIG.

[0056] In one embodiment, the strip-shaped conductor 10 is positioned farther from the heat generating unit 6 in the sub-scanning direction Ds than the drive circuit unit 7. This allows the print medium to be neutralized upstream of the drive circuit unit 7 in the transport direction, thereby effectively protecting the drive circuit unit 7. The strip-shaped conductor 10 may be positioned farther from the heat generating unit 6 than the position shown in FIG. 2 as long as it is positioned on the main surface 4a of the FPC 4, but it is preferable that it is not positioned too far from the heat generating unit 6. That is, if the strip-shaped conductor 10 in the thermal head 1 illustrated in FIG. 2 were positioned on the main surface 4b of the FPC 4, when the thermal head 1 is installed in a printer, the distance between the print medium and the strip-shaped conductor 10 would be greater than if it were positioned on the main surface 4a due to the step between the main surfaces 4a and 4b (see also FIG. 1). This can make it difficult to neutralize the print medium upstream of the heat generating unit 6.

[0057] In one embodiment, the length of the strip-shaped conductor 10 in the main scanning direction Dp is configured to be the same as or longer than the length of the heat generating portion 6 in the main scanning direction Dp, thereby making it possible to effectively protect each heat generating element 6a of the heat generating portion 6 extending in the main scanning direction Dp from static electricity.

[0058] In one embodiment, the length of the strip-shaped conductor 10 in the main scanning direction Dp is configured to be equal to or longer than the maximum paper width that can be printed on a print medium such as a label that is transported by a printer equipped with the thermal head 1. Since electrostatic discharge can occur across the entire maximum paper width of the print medium, making the length of the strip-shaped conductor 10 equal to or greater than the maximum paper width of the print medium makes it possible to effectively protect the thermal head 1 from static electricity.

[0059] The path of the conductive tape 11 is not limited to that shown in Fig. 2. It is also preferable to form the conductive tape 11 so that, when viewed from the normal direction of the main surfaces 4a and 4b of the FPC 4, the path does not overlap with the wiring pattern of the electronic circuit unit 81 provided on the FPC 4. This makes it possible to suppress the influence of static electricity on the wiring pattern in the FPC 4 (for example, the influence of noise superposition) when dissipating static electricity.

[0060] Next, a thermal head including a conductive member other than the conductive tape 11 (FIG. 2) as a member for electrically connecting the strip-shaped conductor 10 and the signal ground 82 will be described with reference to FIGS. 5 to 7.

[0061] The thermal head 1A shown in Figure 5 differs from the thermal head 1 (Figure 2) in that the strip-shaped conductor 10 and the signal ground 82 are electrically connected by a jumper wire 12 (an example of a conductive member). Both ends of the jumper wire 12 are soldered to the strip-shaped conductor 10 and the signal ground 82, respectively. Using the jumper wire 12 has the advantage of ensuring a more reliable electrical connection between the strip-shaped conductor 10 and the signal ground 82. In this case, too, it is preferable to provide the jumper wire 12 so that the end 10e of the strip-shaped conductor 10 and the signal ground 82 are connected via the shortest path.

[0062] Unlike the thermal head 1 ( FIG. 2 ), the thermal head 1B shown in FIG. 6 electrically connects the strip-shaped conductor 10 and the signal ground 82 via an FPC 13 (an example of a conductive member and a flexible substrate). The FPC 13 has a predetermined conductive pattern formed on its substrate, which is electrically connected to the strip-shaped conductor 10 and the signal ground 82. The FPC 13 is configured so that the conductive pattern is exposed at least at both ends. The exposed portions of the conductive pattern are bonded to the strip-shaped conductor 10 and the signal ground 82, respectively, using, for example, a conductive adhesive. For example, an end 131 of the FPC 13 is exposed and bonded to the end 10e of the strip-shaped conductor 10. Even when the FPC 13 is provided, it is preferable to connect the end 10e of the strip-shaped conductor 10 to the signal ground 82 via the shortest route. In the thermal head 1B, static electricity from the print medium is discharged from the strip-shaped conductor 10 to the conductive pattern of the FPC 13 to the signal ground 82. In the FPC 13, the conductive pattern is covered with an insulating material (substrate or coverlay), so the impact on the electronic circuit section 81 of the FPC 4 while the charge is moving from the strip-shaped conductor 10 to the signal ground 82 can be suppressed.

[0063] In one embodiment, the strip-shaped conductor 10 is electrically connected to the signal ground 82 via the heat dissipation portion 5. In other words, the heat dissipation portion 5 can be used as a discharge path for dissipating static electricity conducted to the strip-shaped conductor 10 to the signal ground 82. The thermal head 1C shown in FIG. 7 is an example of a thermal head in which a discharge path is formed using the heat dissipation portion 5. In the thermal head 1C, the strip-shaped conductor 10 is electrically connected to the heat dissipation portion 5 via a first conductive tape 14 (an example of a first conductive member), and the signal ground 82 is electrically connected to the heat dissipation portion 5 via a second conductive tape 15 (an example of a second conductive member). Therefore, a discharge path is formed for static electricity from the print medium, from the strip-shaped conductor 10 to the first conductive tape 14 to the heat dissipation portion 5 to the second conductive tape 15 to the signal ground 82, thereby protecting the thermal head 1 from electrostatic discharge from the print medium PM. In the thermal head 1C, the strip-shaped conductor 10 and the signal ground 82 can be electrically connected simply by attaching the first conductive tape 14 and the second conductive tape 15 to the heat dissipation portion 5 .

[0064] As described above, in the thermal heads of the above-described embodiments, the strip-shaped conductors 10 are arranged in parallel with the heat generating units 6 along the main scanning direction Dp. In the thermal heads 1, 1A, and 1B, the strip-shaped conductors 10 are electrically connected directly to the signal ground 82 via a conductive member. Furthermore, in the thermal head 1C, the strip-shaped conductors 10 are electrically connected to the signal ground 82 via the conductive heat dissipation unit 5. The strip-shaped conductors 10 are arranged closer to the drive circuit unit 7 than the heat generating units 6 in the sub-scanning direction Ds. More preferably, the strip-shaped conductors 10 are arranged farther from the heat generating units 6 than the drive circuit unit 7 in the sub-scanning direction Ds. This allows charge due to electrostatic discharge from the print medium to escape upstream in the print medium transport direction, thereby suppressing the effects of electrostatic discharge on the heat generating units 6 and the drive circuit unit 7 (e.g., effects such as noise superposition). If some of the heat generating elements in the heat generating unit 6 are damaged due to electrostatic discharge, the damaged heat generating elements will not generate heat and printing will be impossible. This requires the thermal head installed in the printer to be replaced, and labels cannot be printed during that time. In contrast, the thermal head of the above-described embodiment prevents damage to the heating element, so it is possible to avoid situations where labels cannot be printed.

[0065] As shown in FIG. 2 , the protective film 62 can be formed to cover the heating element 6a. Because electrostatic discharge from the print medium can cause pinholes in the protective film, which can then damage the heating element, it is preferable that the protective film 62 be thick from the perspective of protection from electrostatic discharge. On the other hand, as mentioned above, a thin protective film 62 is preferable from the perspective of printing performance. In the thermal head of the above-described embodiment, a discharge path is formed upstream of the heating element 6 in the transport direction to allow static electricity from the printing medium to escape, thereby protecting the heating element 6 from electrostatic discharge. Therefore, even if the protective film 62 is thin, durability is not affected. In other words, the thermal head of the above-described embodiment has the advantage of protecting the thermal head from electrostatic discharge, thereby extending its lifespan and improving printing performance.

[0066] When printing on an RFID label (a label incorporating an RFID inlay) using the thermal head of each of the above-described embodiments, it is possible to prevent damage to the IC chip included in the RFID inlay due to electrostatic discharge from the RFID label. In RFID inlays, an antenna made of aluminum or the like is formed by vapor deposition on an insulating resin film, and if static electricity is not sufficiently removed, the IC chip may be damaged by discharge to the antenna. The thermal head of the above-described embodiments can suppress the effects of electrostatic discharge from the RFID label, thereby protecting the IC chip included in the RFID label.

[0067] In the thermal heads 1, 1A, and 1B, the conductive tape 11 (FIG. 2), jumper wire 12 (FIG. 5), and FPC 13 (FIG. 6) are each arranged along the surface on which the heat-generating portion 6 is provided. When the conductive tape 11 and FPC 13 are used, they are arranged in close contact with the surface on which the heat-generating portion 6 is provided. This allows the strip-shaped conductor 10 and the signal ground 82 to be electrically connected via the shortest path, shortening the static electricity discharge path and more effectively preventing damage to the heat-generating portion 6 due to static electricity discharge.

[0068] In the illustrated example, the heat generating unit 6 and the drive circuit unit 7 are arranged on the rigid substrate 3, the electronic circuit unit 81 is arranged on the FPC 4, and the conductive tape 11 ( FIG. 2 ), jumper wires 12 ( FIG. 5 ), and FPC 13 ( FIG. 6 ) are arranged along the main surface 3 a of the rigid substrate 3 and / or the main surfaces 4 a and 4 b of the FPC 4. However, the thermal head is not limited to arranging the drive circuit unit 7 on the rigid substrate 3 and the electronic circuit unit 81 on the FPC 4. This specific arrangement corresponds to the configuration of the rigid substrate 3 and FPC 4 illustrated in FIG. 2 . If the configuration of the rigid substrate 3 and FPC 4 differs from that shown in FIG. 2 , the arrangement of the drive circuit unit 7 and the electronic circuit unit 81 may differ from that shown in FIG. 2 .

[0069] In one embodiment, the strip-shaped conductor 10 is disposed on the rigid substrate. For example, if the rigid substrate is longer in the sub-scanning direction Ds than that shown in FIG. 2 , the strip-shaped conductor 10 can be disposed on the rigid substrate. In this case, the conductive member connecting the strip-shaped conductor 10 and the signal ground 82 is provided across the boundary between the rigid substrate and the FPC 4.

[0070] In one embodiment, the thermal head is constructed solely from a rigid substrate without using an FPC 4, with the heating section, drive circuit section, and electronic circuit section all disposed on the rigid substrate. In this case, the conductive member connecting the strip-shaped conductor 10 and the signal ground 82 is configured to be disposed along the main surface of the rigid substrate. The strip-shaped conductor 10, the signal ground 82, and the conductive member connecting the strip-shaped conductor 10 and the signal ground 82 are all disposed on the main surface of the rigid substrate.

[0071] Although the embodiment of the thermal head has been described above, the present invention is not limited to the above embodiment. Furthermore, the above embodiment can be improved or modified in various ways without departing from the spirit of the present invention.

[0072] The present invention is related to patent application No. 2024-070183, filed with the Japan Patent Office on April 24, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A thermal head comprising: a plurality of heating elements arranged in a main scanning direction; a drive circuit section arranged in parallel to the plurality of heating elements along the main scanning direction and causing the plurality of heating elements to selectively generate heat; an electronic circuit section having wiring that supplies signals to the drive circuit section and a signal ground; and a strip-shaped conductor that is arranged closer to the drive circuit section than the plurality of heating elements in the sub-scanning direction and arranged in parallel to the plurality of heating elements along the main scanning direction, wherein the strip-shaped conductor is electrically connected to the signal ground.

2. The thermal head according to claim 1, wherein the strip-shaped conductor is provided at a position farther from the plurality of heating elements than the drive circuit section in the sub-scanning direction.

3. A thermal head as described in claim 1, wherein the length of the strip-shaped conductor in the main scanning direction is the same as or longer than the length of the plurality of heating elements in the main scanning direction.

4. The thermal head according to claim 1, wherein the strip-shaped conductor is electrically connected to the signal ground via the shortest path from at least one of one end and the other end in the longitudinal direction.

5. The thermal head according to claim 1, further comprising a protective film covering the plurality of heating elements.

6. A thermal head according to any one of claims 1 to 5, wherein the strip-shaped conductor is electrically connected directly to the signal ground via a conductive member.

7. The thermal head according to claim 6, wherein the conductive member is disposed along the surface of the thermal head on which the plurality of heating elements are provided.

8. A thermal head as described in claim 7, comprising: a rigid substrate on which the plurality of heating elements and the drive circuit section are arranged; and a flexible substrate on which the electronic circuit section is arranged, wherein the conductive member is arranged along the substrate surface of the rigid substrate and / or the flexible substrate.

9. The thermal head according to claim 6, wherein the conductive member is a conductive tape.

10. The thermal head according to claim 6, wherein the conductive member is a jumper wire soldered to the strip-shaped conductor and the signal ground.

11. A thermal head according to claim 6, wherein the conductive member is a flexible substrate on which a predetermined conductive pattern is formed, and the conductive pattern is electrically connected to the signal ground.

12. A thermal head as described in any one of claims 1 to 5, further comprising an electrically conductive heat dissipation section that dissipates heat generated in the thermal head, and the strip-shaped conductor is electrically connected to the signal ground via the heat dissipation section.

13. A thermal head according to claim 12, wherein the strip-shaped conductor is electrically connected to the heat dissipation portion via a first conductive member, and the signal ground is electrically connected to the heat dissipation portion via a second conductive member.

14. A thermal head according to any one of claims 1 to 5, wherein the strip-shaped conductor is copper foil.

15. A printer comprising: a thermal head according to any one of claims 1 to 14; and a control board having a ground terminal and connected to the thermal head via a connector, wherein the signal ground and the ground terminal are electrically connected via the connector.

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