JP2017177391A - Thermal print head, method for manufacturing the same, and thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal print head enabling improvement in grounding quality of a discharging film.SOLUTION: A thermal print head is improved in grounding quality as follows: one surface of an insulation substrate is provided with a plurality of heat generation resistors 13, a plurality of electrodes 14, 15, and a protection film 17 coating a grounding terminal 14, the plurality of heat generation resistors 13 and the plurality of electrodes 14, 15; one surface of the protection film 17 is coated with a discharge film 18; the protection film 17 is provided with a hole part 17A on which the grounding terminal 14 is exposed; the edge of the hole part 17A is provided with projection parts 17AX each the width of which is gradually narrowed to its tip end from its bottom, the thickness of which is gradually thinned and the arch-like surface of which is inclined; and the discharging film 18 is coated ranging from one surface of the protection film 17 to the grounding terminal 14 of the bottom of the hole part 17A via the projection parts 17AX, thereby the discharging film 18 is coated on the surfaces of the projection parts 17AX of the protection film 17 to be prevented from breakage while improving bonding force by being pressed among portions where the film is coated on the grounding terminal 14 around.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a thermal print head, a manufacturing method thereof, and a thermal printer provided with the thermal print head.

  The thermal print head generates heat from a plurality of heating resistors arranged in a heat generating area along the main scanning direction, and images of characters, figures, etc. are recorded on a recording medium such as thermal recording paper by the heat of the plurality of heating resistors. This is an output device to be formed. Thermal print heads are widely used in thermal printers (that is, recording devices) such as barcode printers, digital plate-making machines, video printers, imagers, and seal printers.

  In a general thermal print head, a head substrate and a circuit board are arranged on one surface of a heat sink long in the main scanning direction. In the head substrate, a plurality of heating resistors that are long in the sub-scanning direction are arranged in order in the main scanning direction via a glaze layer on the support substrate, and a common electrode and a plurality of electrodes are arranged at both ends of the plurality of heating resistors. Individual electrodes are arranged, and these form a plurality of heating elements. In the head substrate, a protective film is formed on one surface of the glaze layer to cover the plurality of heating resistors, the common electrode, and the individual electrodes.

  A circuit board has a plurality of driving ICs (Integrated Circuits) having a switching function capable of controlling a plurality of heat generating elements arranged in one row in the main scanning direction. The plurality of driving ICs are respectively connected to a plurality of individual electrodes via a plurality of bonding wires. The plurality of driving ICs are sealed together with a plurality of bonding wires by a sealing body that is applied and formed at the boundary between the head substrate and the circuit board.

  In a thermal printer provided with such a thermal print head, the platen roller has a roller shaft in parallel with the main scanning direction, and the roller is in a state where the outer peripheral surface is in contact with a portion corresponding to the heat generation area of the protective film of the head substrate. It is provided so as to be rotatable about an axis. As a result, the thermal printer selectively causes the plurality of heating resistors to generate heat while the recording medium inserted between the platen roller and the protective film of the head substrate is conveyed in the sub-scanning direction by the rotation of the platen roller. Thus, a desired image was formed on the surface of the recording medium.

  In the thermal printer, static electricity is generated by sliding the recording medium against the protective film of the head substrate by the platen roller during image formation, and the surface of the protective film is charged. In the thermal printer, if the surface of the protective film is charged due to static electricity, the protective film may cause a dielectric breakdown and discharge to the heating element, which may be destroyed.

  For this reason, the conventional thermal print head forms a rectangular through hole with an inclined hole edge on one surface of the protective film on the head substrate to expose a part of the common electrode and to dispose a conductive charge removal film. Then, the charge removal film is connected to the common electrode in the through hole. As a result, the thermal print head slides the recording medium against the charge removal film on the head substrate during image formation, and even if static electricity is generated, the common electrode functions as a ground terminal, and the static electricity is transferred from the charge removal film to the common electrode. It was escaped (see, for example, Patent Document 1).

JP-A-2006-181822 (6th page, 7th page, FIG. 5)

  By the way, in the conventional thermal print head, when the image is formed, the platen roller is rotated in a state of being pressed against the charge removal film, so that stress is easily generated on the head substrate. Further, in the thermal print head, for example, if the adhesion of the charge removal film to the hole edge of the protective film is low, the charge removal film may be peeled off from the hole edge of the protection film due to stress generated on the head substrate.

  In the thermal print head, when the charge removal film breaks, the static electricity generated by the sliding of the recording medium with respect to the charge removal film cannot be released to the common electrode, causing the dielectric breakdown of the protective film and protecting the heating element. Disappear. For this reason, in the conventional thermal print head, the hole edge portion of the protective film of the head substrate is inclined to improve the adhesion of the charge removal film.

  However, in thermal print heads, if the adhesion of the static elimination film to the hole edge of the protective film is not improved, the static elimination film may peel off from the hole edge of the protective film and break when the head substrate is stressed. There is a problem that it is difficult to improve the grounding quality of the charge removal film.

  Therefore, the present invention proposes a thermal print head that can improve the grounding quality of the charge removal film, a manufacturing method thereof, and a thermal printer.

  In order to solve this problem, in the present invention, in a thermal print head, an insulating substrate, a plurality of heating resistors arranged side by side in the main scanning direction on one surface of the insulating substrate, and a surface of the insulating substrate are arranged. A plurality of electrodes connected to the heat generating resistor, a ground terminal disposed on one surface of the insulating substrate, a protective film disposed on one surface of the insulating substrate and covering the plurality of heat generating resistors and the plurality of electrodes, and a protective film And a hole for exposing the ground terminal to the protective film. The width of the hole is gradually narrowed from the root to the tip, and the thickness is gradually reduced. Then, a projecting portion for inclining the bow-shaped surface was provided, and the charge removal film was applied from one surface of the protective film to the ground terminal at the bottom of the hole portion through the projecting portion.

  Therefore, in the present invention, the static elimination film is applied to the surface of the protruding portion of the protective film so as to be pressed between the places where the static elimination film is applied to the surrounding ground terminal, thereby improving the adhesive force, and stress is generated on the insulating substrate. However, it can prevent that the static elimination film peels off from the protrusion part of a protective film, and it fractures | ruptures by the stress.

  According to the present invention, in the thermal print head, the insulating substrate, the plurality of heating resistors arranged in one side of the main scanning direction on one surface of the insulating substrate, the plurality of heating resistors arranged on the one surface of the insulating substrate, A plurality of electrodes to be connected, a ground terminal disposed on one surface of the insulating substrate, a protective film disposed on one surface of the insulating substrate and covering the plurality of heating resistors and the plurality of electrodes, and attached to one surface of the protective film A hole that exposes the grounding terminal to the protective film, and gradually reduces the width from the root to the tip of the hole, and gradually decreases the thickness to create a bow shape. The surface of the protrusion of the protective film is formed by providing a protrusion that inclines the surface of the protective film and depositing the charge removal film from one surface of the protective film to the ground terminal at the bottom of the hole through the protrusion. And between the places attached to the surrounding ground terminals Even if stress is applied to the insulating substrate and the insulating substrate is stressed so as to improve the adhesion, it is possible to prevent the antistatic film from being peeled off from the protruding portion of the protective film and broken. It is possible to realize a thermal print head that can improve the grounding quality, a manufacturing method thereof, and a thermal printer.

1 is a perspective view showing an external configuration of a thermal print head according to an embodiment of the present invention. It is sectional drawing which shows the structure of the thermal print head which concerns on embodiment of this invention. It is a top view which shows the structure of the protective film arrange | positioned on one surface of an insulated substrate. It is the fragmentary top view and fragmentary sectional view which show the structure of the protective film arrange | positioned at one surface of an insulated substrate. It is a top view which shows the structure of the static elimination film arrange | positioned on one surface of an insulated substrate. It is the fragmentary top view and fragmentary sectional view which show the structure of the static elimination film arrange | positioned on one surface of an insulated substrate. It is the partial top view and partial sectional view which show a board | substrate manufacturing process (1). It is the partial top view and partial sectional view which show a board | substrate manufacturing process (2). It is the partial top view and partial sectional view which show a board | substrate manufacturing process (3). It is the partial top view and partial sectional view which show a board | substrate manufacturing process (4). It is the partial top view and partial sectional view which show a board | substrate manufacturing process (5). It is sectional drawing which shows the structure of the thermal printer provided with the thermal print head concerning embodiment of this invention.

  Embodiments of a thermal print head and a thermal printer according to the present invention will be described with reference to FIGS. Incidentally, FIG. 2 is a cross-sectional view taken along the line V1-V1 of FIG. 4B and 6B to 11B are cross-sectional views taken along arrows V2-V2 of FIGS. 4A and 6A to 11A. Note that this embodiment is merely an example, and the present invention is not limited to this.

  As shown in FIGS. 1 and 2, the thermal print head 1 includes a heat radiating plate 5, a head substrate 6, a circuit substrate 7, and a plurality of driving ICs 8. The heat radiating plate 5 is made of a metal having good heat radiating properties such as aluminum and has a rectangular shape that is long in the main scanning direction S1. The heat radiating plate 5 has a circuit board 7 and a head substrate 6 arranged on one side in the sub-scanning direction S2 orthogonal to the main scanning direction S1.

The head substrate 6 has a glaze layer 11 made of a glass film such as silicon dioxide (SiO ₂ ) on one surface of a support substrate 10 made of ceramic such as rectangular aluminum oxide (Al ₂ O ₃ ) that is long in the main scanning direction S1. It has an insulating substrate 12 formed by being arranged. On one surface of the insulating substrate 12 (that is, one surface of the glaze layer 11), a plurality of heating resistors 13 that are long in the sub-scanning direction S2 are arranged side by side at a predetermined interval in the main scanning direction S1.

  On one surface of the insulating substrate 12, a strip-like common electrode 14 that is long in the main scanning direction S1 is disposed at one end of the substrate in the sub-scanning direction S2. The common electrode 14 is provided with a plurality of electrode ends that are long in the sub-scanning direction S2 and arranged at predetermined intervals in the main scanning direction S1 at the edge in the sub-scanning direction opposite to the sub-scanning direction S2. The common electrode 14 is connected to the plurality of heating resistors 13 such that one end of the plurality of electrodes covers one end of the resistor in the sub-scanning direction S2 of the plurality of heating resistors 13.

  Further, on one surface of the insulating substrate 12, a plurality of individual electrodes 15 that are long in the sub-scanning direction S2 are arranged at predetermined intervals in the main scanning direction S1, near the other end of the substrate in the sub-scanning direction. The plurality of individual electrodes 15 are connected to the plurality of heating resistors 13 such that one end of the electrodes covers the other end of the resistors in the sub-scanning direction of the plurality of heating resistors 13.

  As a result, the head substrate 6 includes a plurality of heating elements each having one heating resistor 13 by the plurality of heating resistors 13, the common electrode 14, and the plurality of individual electrodes 15. In each of the plurality of heat generating elements, a portion between one electrode end portion of the common electrode 14 and one electrode end portion of the individual electrode 15 in one heat generating resistor 13 is a heat generating portion that generates heat when energized. Therefore, in the head substrate 6, a belt-shaped region along the main scanning direction S <b> 1 in which the heat generating portions of the plurality of heat generating elements are sequentially arranged is a heat generating region 16.

  Incidentally, the common electrode 14 has, for example, an electrode other end portion (not shown) provided on at least one of the edge in the main scanning direction S1 and the opposite edge in the main scanning direction along the substrate side end portion. And routed to the other end of the substrate. Each of the plurality of individual electrodes 15 is provided with a bonding pad 15A at the other end of the electrode located at the other end of the substrate.

Furthermore Figure 2, Figure 3, as shown in FIG. 4 (A) and (B), on one surface of the insulating substrate 12, except for the substrate and the other end portion, the silicon oxide film (Si0 ₂₎ or silicon oxynitride film (SiON A protective film 17 having oxidation resistance and wear resistance such as) is disposed. As a result, the head substrate 6 is covered with the plurality of heating resistors 13 and the common electrode 14 and the electrode one end side of the plurality of individual electrodes 15 (that is, the portion excluding the bonding pad 15A) by the protective film 17.

  However, the protective film 17 has a rectangular hole 17A that is long in the main scanning direction S1 at one end in the sub-scanning direction S2, and the central portion of the common electrode 14 is exposed through the hole 17A. Further, the protective film 17 has a plurality of semi-conical or semi-elliptical pyramidal projections 17AX whose apex angle is more acute than 45 [°], for example, at the edge of the hole 17A in the sub-scanning direction S2. Are arranged side by side in the main scanning direction S1 toward the inner side (that is, in the direction opposite to the sub-scanning direction).

  Further, the protective film 17 is provided with a plurality of similar protrusions 17AX arranged at the edge of the hole portion 17A in the sub-scanning direction in a row in the main scanning direction S1 with the tip directed inside the hole portion 17A (ie, the sub-scanning direction S2). It has been. That is, at the edge of the hole 17A of the protective film 17, a plurality of protrusions are formed by gradually narrowing the width from the root to the tip and gradually reducing the thickness so that the bow-shaped surface having no corners or steps is gently inclined. A portion 17AX is provided.

  As shown in FIGS. 2, 5, 6A and 6B, on one surface of the protective film 17, a static elimination film which is a conductive metal film is formed from the center to one end in the sub-scanning direction S2. 18 is attached. That is, the charge removal film 18 is attached to almost the entire portion including the portion corresponding to the heat generating region 16 on one surface of the protective film 17.

  Further, the charge removal film 18 is also applied from the edge of the hole 17A of the protective film 17 to the center of the common electrode 14 serving as the bottom of the hole 17A via the plurality of protrusions 17AX. Thereby, the charge removal film 18 covers one surface of the protective film 17, and a part thereof is connected to the central portion of the common electrode 14 through the hole 17 </ b> A.

  Here, the protective film 17 has a plurality of protrusions 17AX each having a bow shape with no corners or steps, and is gently inclined toward the common electrode 14 from the root to the tip. Therefore, the protective film 17 improves the adhesion of the charge removal film 18 to the surfaces of the plurality of protrusions 17AX.

  Further, the common electrode 14 is exposed from between each of the plurality of projecting portions 17AX of the protective film 17 to the periphery thereof, and a charge removal film 18 is attached to the exposed portion. Therefore, the charge removal film 18 presses the surface of each of the plurality of protrusions 17AX of the protective film 17 between the portions attached to the common electrode 14 around the protrusions 17AX, so that the plurality of protrusions 17AX. It is attached to the surface of the surface with increased adhesion.

  The head substrate 6 is attached to the other surface of the insulating substrate 12 (that is, the other surface of the support substrate 10) on one end of one surface of the heat radiating plate 5 via an adhesive 19 that is a thermoplastic resin such as double-sided tape or silicon resin. Is glued.

  The circuit board 7 (FIGS. 1 and 2) is formed as a printed wiring board that is long in the main scanning direction S1, or is formed by sticking a flexible board to a ceramic plate that is long in the main scanning direction S1. The circuit board 7 has one end surface in contact with or close to the other end surface of the head substrate 6, and one end portion of the other surface is bonded to the other end portion of one surface of the heat sink 5 via an adhesive 19. Incidentally, the circuit board 7 has connectors 20 and 21 mounted on the other end of the other surface. The connectors 20 and 21 are for inputting driving power, a control signal for the driving IC 8 and the like to the circuit board 7 from the outside, and grounding the circuit board 7 to an external ground.

  The plurality of driving ICs 8 are control elements each having a switching function capable of controlling a plurality of heating elements (that is, heat generation of the heating resistor 13). The plurality of driving ICs 8 are arranged side by side in the main scanning direction S1 at one end portion of one surface of the circuit board 7 (that is, the boundary portion with the head substrate 6). The plurality of driving ICs 8 are connected to the bonding pads 15A of the plurality of individual electrodes 15 and the plurality of electrodes (not shown) of the circuit board 7 through the plurality of bonding wires 23 and 24.

  Incidentally, the other end of the common electrode 14 is connected to the electrode of the circuit board 7 through a bonding wire (not shown). The plurality of driving ICs 8 include a plurality of bonding wires 23 and 24 (including bonding wires for connecting the common electrode 14 and the circuit board 7), near the boundary between one surface of the circuit board 7 and one surface of the head substrate 6. It is sealed with a sealing body 25 made of an epoxy resin.

  Here, a substrate manufacturing process for manufacturing the head substrate 6 in the manufacturing process of the thermal print head 1 will be described. First, in the substrate manufacturing process, after the glaze layer 11 is fused to one surface of the support substrate 10 to form the insulating substrate 12, a resistor layer and a conductor layer are formed on one surface of the insulating substrate 12 by a thin film forming apparatus such as a sputtering apparatus. Are sequentially stacked. In the substrate manufacturing process, for example, a conductive layer is formed on one surface of the insulating substrate 12 by a photo-engraving process to form the common electrode 14 and the plurality of individual electrodes 15, and then the resistor layer is formed to form a plurality of resistor layers. A heating resistor 13 is formed.

  Incidentally, the heating resistor 13 is a silicon oxide film doped with tantalum (Ta) or the like, and has a thickness of about 1 [μm]. The common electrode 14 and the plurality of individual electrodes 15 are made of, for example, aluminum (Al), gold (Au), silver (Ag), copper (Cu), nickel (Ni), chromium (Cr), titanium (Ti), tungsten ( W), or an alloy containing these as a main component, or a laminate of these metals or alloys, for example, having a thickness of about 1 [μm].

Next, as shown in FIGS. 7A and 7B, in the substrate manufacturing process, the protective film layer 30 made of a silicon oxide film (SiO ₂ ), a silicon oxynitride film (SiON) or the like is formed on the entire surface of the insulating substrate 12. For example, with a thickness of about 1 [μm] to 5 [μm]. Thus, in the substrate manufacturing process, the plurality of heating resistors 13, the common electrode 14 and the plurality of individual electrodes 15 on one surface of the insulating substrate 12, and the exposed glaze layer 11 are covered with the protective film layer 30.

  Subsequently, as shown in FIGS. 8A and 8B, in the substrate manufacturing process, for example, a photoresist 31 made of a negative or positive dry film resist or a liquid resist is applied to the entire surface of the protective film layer 30. Lamination is performed with a thickness of about [μm] to 50 [μm]. In the substrate manufacturing process, the photoresist 31 is exposed through a mask (not shown) patterned in accordance with the shape of one surface of the protective film 17 and then developed.

  Thereby, in the substrate manufacturing process, the photoresist 31 is formed on one surface of the protective film layer 30 into a shape corresponding to the mask pattern. That is, in the substrate manufacturing process, the photoresist 31 is developed, and the apex angles corresponding to the resist hole portions 31A corresponding to the hole portions 17A of the protective film 17 and the plurality of protruding portions 17AX are more acute than 45 [°], for example. And having a plurality of triangular resist protrusions 31AX. In the following description, the photoresist 31 formed by development is also referred to as a development resist 31.

  By the way, in general, the development resist has a sharp triangular protrusion of 45 [°] or less when the thickness is a predetermined thickness or more, for example, about 40 [μm] to 50 [μm]. In the portion, the adhesiveness to the underlying substance tends to gradually decrease from the base of the protrusion to the tip. For this reason, also in the developing resist 31, the adhesiveness of the plurality of resist protrusions 31AX to one surface of the protective film layer 30 gradually decreases from the root to the tip.

  Then, as shown in FIGS. 9A and 9B, in the substrate manufacturing process, the protective film layer 30 is dry-etched or wet-etched using the developing resist 31 as an etching mask. Thus, in the substrate manufacturing process, the other end portion of the protective film layer 30 (that is, the portion not covered with the developing resist 31) is removed from one surface of the insulating substrate 12 to expose the bonding pads 15A of the plurality of individual electrodes 15. . Further, in the substrate manufacturing process, a portion corresponding to the resist hole 31A in the protective film layer 30 is removed from one surface of the insulating substrate 12 to form the hole 30A, and the central portion of the common electrode 14 is exposed.

  Furthermore, the adhesiveness of the plurality of resist protrusions 31AX to one surface of the protective film layer 30 gradually decreases from the base to the tip. Therefore, in the substrate manufacturing process, an etching gas or an etchant is introduced between the plurality of resist protrusions 31AX and the corresponding plurality of hole edges 30AX of the protective film layer 30, respectively. Thereby, in the substrate manufacturing process, the removal amount of the plurality of hole edge portions 30AX of the protective film layer 30 is gradually increased from the root to the tip where the adhesion is lowered according to the degree of adhesion to the resist protrusion 31AX. Remove to reduce the thickness.

  In this way, in the substrate manufacturing process, the protective film layer 30 is formed in the shape of the protective film 17 between one surface of the insulating substrate 12 and the developing resist 31. That is, in the substrate manufacturing process, although the protective film 17 is provided with a plurality of protrusions 17AX having a special semi-conical shape or semi-elliptical pyramid shape, depending on the shape of the protective film 17 using the characteristics of the developing resist 31. The plurality of protrusions 17AX of the protective film 17 can be easily formed only by etching the protective film layer 30 using the developed resist 31 as an etching mask.

  Then, as shown in FIGS. 10A and 10B, in the substrate manufacturing process, the developing resist 31 is peeled from one surface of the formed protective film layer 30. Thus, the protective film 17 is formed on one surface of the insulating substrate 12 in the substrate manufacturing process.

  Next, as shown in FIGS. 11A and 11B, in the substrate manufacturing process, the neutralization film 18, which is a conductive metal film, is formed, for example, by 0 or the like from the center to one end of one surface of the protective film 17 by sputtering or the like. It is applied with a thickness of about 1 [μm] to 0.4 [μm]. Thus, in the substrate manufacturing process, the neutralization film 18 covers most of the portion including the portion corresponding to the heat generation region 16 on one surface of the protective film 17, and the neutralization film 18 is shared through the hole 17 </ b> A of the protective film 17. Connect to the center of the electrode 14.

  Thus, the head substrate 6 is manufactured in the substrate manufacturing process. Incidentally, the charge removal film 18 is formed of, for example, the same conductive material as that of the common electrode 14, and is thus firmly connected to the central portion of the common electrode 14. However, the charge removal film 18 can also be formed of a conductive material different from the common electrode 14.

  A thermal printer 40 provided with such a thermal print head 1 will be described with reference to FIG. The thermal printer 40 has a roller shaft 42 in a state where the platen roller 41 makes the roller shaft 42 parallel to the main scanning direction S1 and the outer peripheral surface is in contact with the portion corresponding to the heat generating region 16 in the charge removal film 18 of the head substrate 6. Is provided so as to be rotatable around the center.

  As a result, the thermal printer 40 rotates the platen roller 41 during image formation, while conveying the recording medium P inserted between the platen roller 41 and the charge removal film 18 of the head substrate 6 in the sub-scanning direction S2. The heating resistor 13 is selectively heated to form a desired image on the surface of the recording medium P. Further, even if static electricity is generated by sliding the recording medium P with respect to the charge removal film 18 of the head substrate 6 at this time, the thermal printer 40 receives the static electricity by the charge removal film 18 and transfers it to the common electrode 14. It can function as a ground terminal and escape.

  In the above configuration, in the thermal print head 1, the plurality of heating resistors 13 are arranged side by side in the main scanning direction S 1 on the one surface of the insulating substrate 12 in the head substrate 6, and the common electrode 14 and the plurality of individual electrodes 15 are arranged. These were connected to a plurality of heating resistors 13. In the thermal print head 1, the protective film 17 covering the plurality of heating resistors 13, the common electrode 14, and the plurality of individual electrodes 15 is disposed on one surface of the insulating substrate 12 in the head substrate 6. In addition, the hole 17A that exposes the central portion of the common electrode 14 is formed, the width of the hole 17A is gradually narrowed from the root to the tip, and the thickness is gradually reduced to form an arcuate surface. The projecting portion 17AX that is gently inclined is provided so as to project to the center of the hole portion 17A.

  In the thermal print head 1, the static elimination film 18 is deposited from one surface of the protective film 17 on the head substrate 6 to the central portion of the common electrode 14 at the bottom of the hole 17 A via the protrusion 17 AX. A part of the film 18 was connected to the central part of the common electrode 14.

  According to the above configuration, the thermal print head 1 presses the static elimination film 18 on the surface of the protrusion 17AX of the protective film 17 between the portions of the head substrate 6 that are attached to the common electrode 14 around it. It can be applied with improved adhesion. Accordingly, when the thermal print head 1 is provided in the thermal printer 40 and forms an image on the recording medium P, the thermal print head 1 is rotated in a state where the platen roller 41 is pressed against the charge removal film 18 and stress is generated on the head substrate 6. The static elimination film 18 can be prevented from being peeled off from the protruding portion 17AX of the protective film 17 due to the stress, and the ground quality of the static elimination film 18 can be improved.

  In the thermal print head 1, a plurality of protrusions 17 </ b> AX are provided on the edge of the hole 17 </ b> A of the protective film 17 in the head substrate 6. Therefore, even if the static elimination film 18 peels off and breaks on the protrusion 17AX due to the stress generated on the head substrate 6, the thermal print head 1 can keep such breakage on some protrusions 17AX. It is possible to avoid a reduction in the grounding quality of the charge removal film 18.

  Further, in the thermal print head 1, a rectangular hole 17A is formed in the protective film 17 on the head substrate 6, and a plurality of protrusions 17AX are provided on different edges of the hole 17A. Therefore, even if the thermal print head 1 has stress concentrated on any part of the head substrate 6 and the charge removal film 18 is peeled off and ruptured on the protrusion 17AX, such a rupture is partially broken. 17AX can be retained, and a reduction in grounding quality of the charge removal film 18 can be avoided.

  Further, in the thermal print head 1, the charge removal film 18 in the head substrate 6 is connected to the common electrode 14 as a ground terminal for releasing static electricity. Therefore, the thermal print head 1 does not need to provide a dedicated ground terminal for grounding the charge removal film 18 on the head substrate 6. In other words, the thermal print head 1 can be grounded by avoiding an increase in size and a complicated configuration of the head substrate 6 by providing a ground terminal.

  In the above-described embodiment, the case where the plurality of protrusions 17AX are provided at the two edges of the protective film 17 has been described. However, the present invention is not limited to this, and only one protrusion 17AX may be provided at the edge of any one of the protective films 17. In the present invention, at least one of the same or different number of protrusions 17AX may be provided at two or more edges of the protective film 17 respectively.

  Further, in the above-described embodiment, the case where the rectangular hole portion 17A is formed in the protective film 17 and the protrusion portion 17AX is provided at the edge of the hole portion 17A has been described. However, the present invention is not limited to this, and a hole 17A having various shapes such as a square shape, an oval shape, and a circular shape is formed in the protective film 17, and at least at least one place on the edge of the hole portion 17A. One or more protrusions 17AX may be provided, and a plurality of protrusions 17AX may be provided around the edge.

  Further, in the above-described embodiment, the case where the common electrode 14 is used as a ground terminal and the charge removal film 18 is connected (that is, grounded) to this is described. However, the present invention is not limited to this, and a dedicated ground terminal may be provided on one surface of the insulating substrate 12, and the charge removal film 18 may be connected (that is, grounded) thereto.

  The present invention can be used for a thermal printer such as a digital plate making machine, a video printer, an imager, and a seal printer, and a thermal print head provided in the thermal printer.

  DESCRIPTION OF SYMBOLS 1 ... Thermal print head, 6 ... Head substrate, 12 ... Insulating substrate, 13 ... Heating resistor, 14 ... Common electrode, 15 ... Individual electrode, 17 ... Protective film, 17A ... Hole, 17AX: Projection, 18: Static elimination film, 30 ... Protective film layer, 31 ... Photoresist, 40 ... Thermal printer.

Claims (6)

An insulating substrate;
A plurality of heating resistors arranged side by side in the main scanning direction on one surface of the insulating substrate;
A plurality of electrodes disposed on one surface of the insulating substrate and connected to the plurality of heating resistors;
A ground terminal disposed on one surface of the insulating substrate;
A protective film disposed on one surface of the insulating substrate and covering the plurality of heating resistors and the plurality of electrodes;
A neutralizing film deposited on one surface of the protective film,
The protective film is
A hole for exposing the ground terminal is formed, and a protrusion is provided at the edge of the hole to gradually narrow the width from the root to the tip and gradually reduce the thickness to incline the bow-shaped surface. And
The charge removal membrane is
A thermal print head attached from one surface of the protective film to the ground terminal at the bottom of the hole through the protrusion. The protective film is
The thermal print head according to claim 1, wherein a plurality of the protrusions are provided on an edge of the hole. The protective film is
The thermal print head according to claim 1, wherein at least one of the protrusions is provided at least at one edge of the hole. The electrode is
A plurality of common electrodes connected to the plurality of heating resistors, and a plurality of individual electrodes connected to the plurality of heating resistors,
The ground terminal is
The thermal print head according to any one of claims 1 to 3, wherein the thermal print head is the common electrode. Forming a plurality of heating resistors on one surface of the insulating substrate in the main scanning direction, forming a plurality of electrodes and a ground terminal, and connecting the plurality of electrodes to the plurality of heating resistors; ,
A second step of laminating a protective film layer covering the plurality of heating resistors, the plurality of electrodes and the ground terminal on one surface of the insulating substrate;
A photoresist having a predetermined thickness or more having a hole corresponding to the ground terminal on one surface of the protective film layer and a triangular protrusion having an acute angle on the edge of the hole is laminated. Etching the protective film layer forms a hole that exposes the ground terminal while covering the plurality of heating resistors and the plurality of electrodes on one surface of the insulating substrate. A third step of forming a protective film provided with protrusions that gradually reduce the width and gradually reduce the thickness from the root to the tip of the edge of the rim, and tilt the bow-shaped surface;
And a fourth step of depositing a charge removal film from one surface of the protective film to the ground terminal at the bottom of the hole through the protrusion. An insulating substrate; a plurality of heating resistors arranged side by side in the main scanning direction on one surface of the insulating substrate; an electrode disposed on one surface of the insulating substrate and connected to the plurality of heating resistors; and the insulation A grounding terminal disposed on one surface of the substrate; a protective film disposed on the one surface of the insulating substrate; covering the plurality of heating resistors and the electrodes; and a neutralizing film deposited on the one surface of the protective film. And a hole for exposing the ground terminal to the protective film is formed, and at the edge of the hole, the width is gradually narrowed from the root to the tip, and the thickness is gradually reduced to provide a bow-shaped surface. A thermal printer comprising a thermal print head provided with a projecting portion that inclines, and wherein the charge removal film is attached from one surface of the protective film to the ground terminal at the bottom of the hole portion through the projecting portion .

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