JP6804328B2 - Thermal print head and its manufacturing method - Google Patents

Description

Embodiments of the present invention relate to thermal printheads and methods of manufacturing them.

The thermal printhead (TPH) heats a plurality of heat generating resistors arranged in a heat generating region along the main scanning direction, and the heat of these multiple heat generating resistors causes characters, figures, etc. on a recording medium such as heat-sensitive recording paper. It is an output device that forms the image of. The thermal print head is widely used in thermal printers (that is, recording devices) such as bar code printers, digital plate making machines, video printers, imagers, and sticker printers.

In the thermal print head, a protective film is provided on the surface of the heat generation resistor to protect the heat generation resistor and the like. The protective film comes into contact with media such as thermal recording paper and ink ribbon during printing, and is rubbed by the medium during paper feeding. At this time, there is a problem that the thermal print head is damaged by the discharge of the electric charge charged on the medium.

Japanese Unexamined Patent Publication No. 2006-181822

Provided are a thermal print head and a method for manufacturing the same, which prevent damage due to discharge of the electric charge charged on the medium.

According to one embodiment, the thermal printhead is provided on the support substrate, the heat generation resistor arranged on the support substrate, and the heat generation resistor, and is provided on the heat generation resistor to supply power to the heat generation resistor. An insulating first protective layer and a second protective layer having a first conductivity, which are provided on the electrodes and the second electrode, the heat generating resistor, the first electrode, and the second electrode. A protective film in which a third protective layer having a second conductivity higher than the first conductivity is laminated in this order is provided, and the protective layer includes the second protective layer to the first protective layer. A stepped opening is provided to expose the first electrode, and the third protective layer is in contact with the first electrode along the inner surface of the opening.

According to one embodiment, in the method of manufacturing a thermal printhead, a heat generating resistor is formed on a glaze layer provided on a support substrate, and a first electrode and a second electrode for supplying power to the heat generating resistor are provided. A step of forming, and a step of sequentially forming an insulating first protective layer and a first conductive second protective layer on the heat generating resistor, the first electrode, and the second electrode. And the step of forming a stepped opening that exposes the first electrode from the second protective layer to the first protective layer, and the second protection having a second conductivity higher than the first conductivity. It comprises a step of forming a third protective layer in contact with the first electrode on the film and along the inner surface of the opening.

According to this embodiment, it is possible to obtain a thermal print head and a method for manufacturing the same, which prevent damage due to discharge of electric charges charged in the medium.

The figure which shows the thermal print head which concerns on Embodiment 1. FIG. The cross-sectional view which shows the static elimination part of the thermal print head which concerns on Embodiment 1. FIG. FIG. 5 is a cross-sectional view showing a main part of a thermal print head of a comparative example according to the first embodiment. The figure which shows the static elimination method of the thermal print head of the comparative example which concerns on Embodiment 1. FIG. The cross-sectional view which shows the static elimination part of the thermal print head of the comparative example which concerns on Embodiment 1. FIG. FIG. 5 is a cross-sectional view showing another static elimination portion of the thermal print head of the comparative example according to the first embodiment. The process chart which shows the manufacturing method of the thermal print head which concerns on Embodiment 1 in order. The process chart which shows the manufacturing method of the thermal print head which concerns on Embodiment 1 in order. The process chart which shows the manufacturing method of the thermal print head which concerns on Embodiment 1 in order. The process chart which shows the manufacturing method of the thermal print head which concerns on Embodiment 1 in order. The process chart which shows the manufacturing method of the thermal print head which concerns on Embodiment 1 in order. The process chart which shows the manufacturing method of the thermal print head which concerns on Embodiment 1 in order. The plan view which shows another static elimination part of the thermal print head which concerns on Embodiment 1. FIG. FIG. 5 is a cross-sectional view showing a main part of another thermal print head according to the first embodiment. The cross-sectional view which shows the thermal printer which concerns on Embodiment 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The thermal printhead according to this embodiment will be described with reference to FIGS. 1 and 2. 1A and 1B are views showing a thermal printhead, FIG. 1A is a plan view thereof, FIG. 1B is a sectional view taken along line V1-V1 of FIG. 1A, and FIG. 2 is a static elimination unit of the thermal printhead. It is sectional drawing which shows. It should be noted that the present embodiment is merely an example, and the present invention is not limited thereto.

First, the thermal print head will be described.
As shown in FIG. 1, the thermal print head 10 has a long head unit 11 that is long in the main scanning direction S1 in which an image can be formed on a recording medium. The head unit 11 has a heat radiating plate 12, a head board 13, a circuit board 14, and a plurality of drive ICs 15.

The heat radiating plate 12 is made of a metal having good heat dissipation such as aluminum, and the heat radiating plate one end surface 12A in the sub-scanning direction S2 orthogonal to the main scanning direction S1 and the direction opposite to the sub-scanning direction S2 (hereinafter, this is sub-scanning). The other end surface 12B of the heat radiating plate (also referred to as the opposite direction) is substantially parallel, and is formed in a long flat plate shape in the main scanning direction S1 having a substantially uniform thickness.

Further, the other end of the heat radiating plate in the direction opposite to the sub-scanning of the heat radiating plate 12 is a circuit board arranging portion in which the circuit board 14 is arranged, and is formed in a long rectangular shape in the main scanning direction S1. The heat radiating plate 12 has a circuit board 14 and a head board 13 arranged side by side in the sub-scanning direction S2 on one surface.

The head substrate 13 is long in the main scanning direction S1, and one end surface 13A of the head substrate in the sub scanning direction S2 and the other end surface 13B of the head substrate in the direction opposite to the sub scanning are substantially parallel to each other.

Actually, the head substrate 13 has a support substrate 16 formed in a rectangular parallelepiped shape by a ceramic such as Al ₂ O ₃ , and the outer shape of the support substrate 16 is the outer shape of the head substrate 13 as it is. The support substrate 16 is provided with a glaze layer 17 made of a glass film such as SiO _{2 on} one surface thereof.

On one surface of the glaze layer 17, a plurality of heat generating resistors 18 long in the sub-scanning direction S2 are arranged in order in the main scanning direction S1 at predetermined in-board resistor arrangement intervals. Further, on one surface of the glaze layer 17, common electrodes (first electrodes) 19 and individual electrodes (second electrodes) 20 are arranged at both ends of the plurality of heat generating resistors 18 along the sub-scanning direction S2, and a plurality of these. A heat generating element is formed by the heat generating resistor 18, the common electrode 19, and the individual electrode 20. As a result, in the head substrate 13, the band-shaped portion along the main scanning direction S1 becomes a heat generating region 21 in which a plurality of heat generating resistors 18 generate heat between the common electrode 19 and the individual electrodes 20.

Further, on one surface of the glaze layer 17, a protective film 22 covering a plurality of heat generating resistors 18, common electrodes 19, and individual electrodes 20 is formed. The protective film 22 has a recess 22a slightly recessed in a portion covering the heat generating resistor 18.

Note that FIG. 1A shows, as a plurality of heat generating resistors 18 arranged on the head substrate 13, the portion between the resistor electrodes of the common electrode 19 and the individual electrodes 20 forming the heat generating region 21 is shown by a solid line. .. Then, in the head substrate 13, the other surface of the support substrate 16 is adhered to one surface of the head substrate arrangement portion of the heat radiation plate 12 via a double-sided tape or an adhesive 23 which is a thermoplastic resin such as silicon resin.

The circuit board 14 is formed as a printed wiring board long in the main scanning direction S1, or a flexible board is attached to a ceramic plate long in the main scanning direction S1. The other surface of the circuit board 14 is adhered to one surface of the circuit board arrangement portion of the heat radiating plate 12 via double-sided tape or an adhesive 23. Incidentally, the circuit board 14 is formed with a connection circuit that is electrically connected to the head board 13 via the drive IC 15, and has a connector (not shown) that inputs drive power and control signals to the connection circuit from the outside. It is implemented.

The plurality of drive ICs 15 are control elements having a plurality of first terminals and second terminals provided on one surface thereof and having a switching function capable of controlling the heat generating element. The plurality of drive ICs 15 are arranged, for example, at one end of the sub-scanning direction S2 on one surface of the circuit board 14 (that is, the boundary portion with the head substrate 13) in order along the main scanning direction S1.

In the plurality of drive ICs 15, the plurality of first terminals are electrically connected to the individual electrodes 20 via the plurality of bonding wires 24. Further, in the plurality of drive ICs 15, the plurality of second terminals are electrically connected to the corresponding substrate electrodes (not shown) formed in the connection circuit of the circuit board 14 via the plurality of bonding wires 25. ..

The plurality of driving ICs 15 are sealed together with the plurality of bonding wires 24 and 25 by a sealing body 26 made of an epoxy resin near the boundary between one surface of the head substrate 13 and one surface of the circuit board 14.

Further, the thermal print head 10 is provided with a static elimination unit 30 for releasing the electric charges charged in the medium such as the thermal paper and the ink ribbon which are sandwiched between the thermal print head 10 and the platen roller described later and sent out in the sub-operation direction S2. Has been done.

The static elimination unit 30 is provided, for example, between the heat generating region 21 and one end surface 13A of the head substrate. The shape of the static elimination unit 30 is, for example, a stepped trench long in the main scanning direction S1. Specifically, the static elimination unit 30 has a rectangular shape that is long in the main scanning direction S1 in a plan view, and has a stepped cross section in the sub scanning direction S2.

Next, the structure of the protective film 22 and the static elimination unit 30 will be described.
As shown in FIG. 2, the protective film 22 is provided on the insulating first protective layer 31 and the first protective layer 31 provided on the heat generating resistor 18, the common electrode 19, and the individual electrodes 20. It has a conductive second protective layer 32 provided in the above, and a conductive third protective layer 33 provided on the second protective layer 32. The second protective layer 32 has a first conductivity, and the third protective layer 33 has a second conductivity different from the first conductivity. The second conductivity is larger than the first conductivity.

The first protective layer 31 is, for example, a silicon oxynitride film (SiON). The second protective layer 32 has an insulating layer 32a in contact with the first protective layer 31 and a conductive layer 32b in contact with the third protective film 33 in order to improve the adhesion with the underlying first protective layer 31. ing. The insulating layer 32a is, for example, the same SiON film as the first protective layer 31, but may be a more oxygen-rich SiON film. The conductive layer 32b may be a silicon film doped with a material that enhances conductivity and strength. The third protective layer 33 is, for example, a silicon oxide film doped with a conductive material.

The thickness of the first protective layer 31 is, for example, about 1.0 μm. The thickness of the SiON film 32 of the second protective layer 32 is, for example, about 1.0 μm, the thickness of the conductive layer 32 is, for example, about 3.0 to 8.0 μm, and the total thickness is, for example, about 4.0 to 9.0 μm. Is. The thickness of the third protective layer 33 is, for example, about 0.4 μm.

The first protective layer 31 is mainly provided to electrically insulate the resistance heating element 18, the common electrode 19, and the individual electrode 20. The second protective layer 32 is provided mainly for ensuring the denseness of the insulating layer 32a, improving the adhesion with the first protective film 31, and ensuring the thermal conductivity of the conductive layer 32b. .. The third protective layer 33 is mainly provided to form a flow path for electric charges.

The first protective layer 31 is a film formed by, for example, a sputtering method or a CVD (Chemical Vapor Deposition) method.

In the static elimination unit 30, the protective film 22 is provided with a stepped opening 34 extending from the second protective layer 32 to the first protective layer 31 and exposing the common electrode 19. The third protective layer 33 is in contact with the common electrode 19 exposed in the opening 34 along the inner surface of the opening 34. Specifically, the stepped opening 34 is provided concentrically with the first opening 34a provided in the first protective layer 31 to expose the common electrode 19 and the first opening 34a provided in the second protective layer 32. It has a second opening 34b that is larger than the opening 34a. The third protective layer 33 is in contact with the common electrode 19 exposed to the first opening 34a along the inner surface of the second opening 34b and the inner surface of the first opening 34a.

The operation of the static elimination unit 30 will be described.
The static elimination unit 30 electrically connects the highly conductive third protective layer 33 to the common electrode 19. The common electrode 19 is connected to a portion having an arbitrary potential via a circuit board 14 or the like. Specifically, the common electrode 19 is connected to the power supply 36 via a resistor 35.

The excess charge 38 charged on the medium 37 such as the thermal paper and the ink ribbon is discharged to the thermal print head 10, particularly the protective film 22. The discharged charge is concentrated on the third protective layer 33 having high conductivity, and is rapidly discharged through the common electrode 19. As a result, it is possible to prevent damage to the thermal print head 10, particularly the protective film 22 and the resistance heating element 18 due to the electric charge 38 charged on the medium 37.

Further, since the opening 34 has a stepped shape having the first opening 34a and the second opening 34b, it is possible to prevent the third protective layer 33 from being cut off. Since the conductive layer has a two-layer structure of a second protective layer 32 having the first conductivity and a third protective layer 33 having a second conductivity higher than the first conductivity, it is possible to further improve the static elimination function. Is. The third protective layer 33 may be lower than the second protective layer 32 in terms of density and protective function.

FIG. 3 is a cross-sectional view showing a main part of the thermal print head of the comparative example. The thermal print head of the comparative example is a thermal print head whose protective film does not have a third protective layer. As shown in FIG. 3, in the thermal printhead of the comparative example, the protective film 40 has only the first protective layer 31 and the second protective layer 32, and does not have the third protective layer 33.

FIG. 4 is a cross-sectional view showing a static elimination method for the thermal print head of the comparative example. As shown in FIG. 4, in the thermal printhead of the comparative example, it is necessary to connect the conductive layer 32b of the second protective layer 32 to a portion having an arbitrary potential by some means. The conductive layer 32b is connected to, for example, a wiring having a reference potential GND. Alternatively, the conductive layer 32b may be connected to the power supply 36 via, for example, a resistor 35.

5 and 6 are cross-sectional views showing a static elimination portion of the thermal print head of the comparative example.
In the example shown in FIG. 5, the conductive agent 41, for example, the conductive paste is applied so as to reach the heat radiating plate 12 from the upper surface of the conductive layer 32b via the side surface of the head substrate 13. The conductive layer 32b is electrically connected to the heat radiating plate 12 via the conductive paste 41. The heat radiating plate 12 is connected to a wiring having a reference potential GND. As a result, the electric charge 38 charged on the medium 37 can be released to the wiring side having the reference potential GND.

In the example shown in FIG. 6, the conductive agent 42, for example, the conductive paste is applied so as to reach the common electrode 19 from the upper surface of the conductive layer 32b via the side surface of the protective film 40. The conductive layer 32b is electrically connected to the common electrode 19 via the conductive paste 42.

The common electrode 19 is connected to the circuit board 14 by a bonding wire 44. The common electrode 19 is connected to a portion having an arbitrary potential via a circuit board 14 or the like. The common electrode 19 is connected to, for example, a wiring having a reference potential GND. Further, the common electrode 19 may be connected to the power supply 36 via, for example, a resistor 35. As a result, the electric charge 38 charged on the medium 37 can be released to the wiring side having the reference potential GND. It is possible to release the electric charge 38 charged in the medium 37 to the power supply 36 side via the resistor 35.

However, in the examples shown in FIGS. 5 and 6, the connection reliability is lowered due to the coating unevenness of the conductive pastes 41 and 42, and the conductive pastes 41 and 42 have a thickness of a predetermined value or more. There is a risk of malfunction. Further, there is a problem that additional steps such as coating of the conductive pastes 41 and 42, formation of the bump ball 43, and connection of the bonding wire 44 are required.

On the other hand, in the thermal print head 10 of the present embodiment, as described above, the protective film 22 has a third protective layer 33 having higher conductivity than the conductive layer 32b of the second protective film 32. The third protective layer 33 covers the common electrode 19 exposed in the stepped opening 34 and is electrically connected to the common electrode 19.

Therefore, higher connection reliability can be obtained than when the conductive pastes 41 and 42 are used. Further, since the third protective layer 33 is as thin as 0.4 μm, there is no problem due to the thickness.

A method of manufacturing the thermal print head 10 will be described.
7 to 12 are diagrams showing the manufacturing process of the thermal print head 10 in order. The flow of the manufacturing process is shown on the left side of FIGS. 7 to 12, and the cross-sectional view is shown on the right side.

First, the manufacturing process of the head substrate 13 will be described.
A glazed ceramic substrate provided with a glaze layer 17 on the ceramic substrate to be the support substrate 16 is prepared (step S10, FIG. 7A).

The glazed ceramic substrate is washed (step S11), and a silicon oxide film doped with a conductive material is formed on the glazed ceramic substrate as a resistance film 50 to be a heat generating resistor 18 by a sputtering method (step S12, FIG. 7 (b). )).

As a result, the heat generating resistor 18 on the glaze layer 17 is obtained.

An aluminum film 52 to be a common electrode 19 and an individual electrode 20 is formed on the heat generation resistor 18 by, for example, a vacuum vapor deposition method (step S16, FIG. 8A).

A register film (not shown) having a pattern corresponding to the heat generating resistor 18, the common electrode 19, and the individual electrode 20 is formed on the aluminum film 52. The resist pattern has a plurality of strips arranged in the main scanning direction S1 at predetermined intervals in the sub-scanning direction S2 in the longitudinal direction, and the ends on the one end surface 13A side of the head substrate are connected by bars. The resist pattern is so-called T-shaped. Further, since the T-shapes are connected in a horizontal row, the shape as a whole is comb-shaped.

The aluminum film 52 and the heat generating resistor 18 are etched using the resist film as a mask. Etching of the aluminum film 52 is performed by, for example, a RIE (Reactive Ion Etching) method using a chlorine-based gas. Etching of the heat generation resistor 18 is performed by, for example, the RIE method using a fluorine-based gas (1PEP in step S17, FIG. 8 (b) -1).

A resist film (not shown) having an opening for exposing the heat generating resistor 18 is formed on the aluminum film 52 patterned with 1 PEP, and the aluminum film 52 is etched using the resist film as a mask (2 PEP in step S17, FIG. 8 (b) -2).

As a result, the strip-shaped aluminum film 52 is divided into two, the portion on the one end surface 13A side of the head substrate becomes the common electrode 19, and the portion on the opposite side to the one end surface 13A of the head substrate becomes the individual electrode 20. The heat generating resistor 18 is exposed in a dot shape between the common electrode 19 and the individual electrode 20.

A SiON film is formed as an insulating first protective layer 31 on the exposed heat generating resistor 18, the common electrode 19, and the individual electrode 20. The SiON film is formed by, for example, a CVD (Chemical Vapor Deposition) method. Alternatively, it can be formed by a sputtering method (step S19, FIG. 9A).

A SiON film to be an insulating layer 32a and a conductive layer 32b are formed on the first protective layer 31 as a second protective layer 32 by a CVD method. After forming the insulating layer 32a, the insulating layer 32a and the conductive layer 32b are continuously formed (step S20, FIG. 9B).

A resist film (first resist film, not shown) having a pattern corresponding to the second opening 34b is formed on the second protective layer 32, and the second protective layer 32 is etched using the resist film as a mask. Etching is performed by the RIE method using, for example, a fluorine-based gas. It is preferable that the etching rates of the conductive layer 32b and the insulating layer 32a are made different, and the etching is stopped when the first protective layer 31 is exposed. As a result, the second opening 34b is formed in the second protective layer 32 (step S21, FIG. 9C).

The second opening 34b is embedded in the second protective layer 32 to form a resist film (second resist film, not shown) having a pattern corresponding to the first opening 34a, and the first protective layer 31 is masked by the resist film. Etch. The thickness of the resist film in the second opening 34b is sufficiently thicker than that of the second protective layer 32. Etching is performed by the RIE method using, for example, a fluorine-based gas. As a result, the first opening 34a is formed in the first protective layer 31. The first opening 34a and the second opening 34b provide a stepped opening 34. The common electrode 19 is exposed in the opening 34 (step S22, FIG. 9D).

A third protective layer 33 is formed on the second protective layer 32, the inner surface of the opening 34, and the common electrode 19 exposed in the opening 34 by a sputtering method or the like. As a result, the highly conductive third protective layer 33 is electrically connected to the common electrode 19 (step S23, FIG. 10A).

Next, the process of assembling the thermal print head will be described.
A heat radiating plate 12 is prepared. The circuit board 14 and the head board 13 are arranged and fixed in order in the sub-scanning direction S2 on one surface of the heat radiating plate 12 via an adhesive (double-sided tape) 23 (step S26, FIG. 11A).

The drive IC 15 is mounted on the circuit board 14. (Step S27, FIG. 11B).

The output terminal (not shown) of the drive IC 15 and the individual electrode 20 of the head substrate 13 are connected via the bonding wire 24. The input terminal (not shown) of the drive IC 15 and the control terminal (not shown) of the circuit board 14 are connected via the bonding wire 25 (step S28, FIG. 11 (c)).

A sealing material containing a filler is applied to the driving IC 15 and the bonding wires 24 and 25 using a dispenser and cured. As a result, the driving IC 15 and the bonding wires 24 and 25 are sealed and protected by the sealing body 26 (step S30, FIG. 12A).

Electrical components such as the capacitor 54 and the connector 55 are soldered to the circuit board 14. As a result, the circuit board 14 can be connected to the outside via the connector 55, and the thermal print head 10 is completed (step S31, FIG. 12B).

As described above, the thermal printhead 10 of the present embodiment has a stepped opening 34, and has a static elimination unit 30 for electrically connecting the third protective layer 33 having high conductivity to the common electrode 19. ing.

As a result, even if the electric charge 38 charged on the medium 37 such as the thermal paper or the ink ribbon is discharged to the thermal print head 10, the static electricity can be quickly removed. Therefore, a thermal printhead that prevents damage due to discharge of the electric charge charged on the medium can be obtained.

Here, the case where the stairs of the opening 34 of the static elimination unit 30 have two steps has been described, but the number of steps is not limited as long as the step coverage of the third protective film is ensured. It may be multi-stage with 3 or more stages. When the stairs of the opening 34 are three steps, the second protective layer 32 is as thick as about 8 μm, so the additional step is provided in the second protective layer 32.

Although the case where the static eliminator 30 is provided between the heat generating region 21 and one end surface 13A of the head substrate and the shape of the static eliminator 30 is a long stepped trench in the main scanning direction S1, the static eliminator 30 is provided. Since the location and the shape of the static elimination unit 30 may be any as long as they secure an escape route for the electric charge charged in the medium, various locations and shapes are possible.

The planar shape of the static elimination unit 30 may be, for example, a circular shape or a polygonal shape. The static elimination unit 30 may be provided discretely in, for example, the main scanning direction S1. The static elimination unit 30 may be provided, for example, between the heat generating region 21 and the sealing body 26, or may be provided inside the sealing body 26.

FIG. 13 is a plan view showing another static elimination unit. In the example shown in FIG. 13A, rectangular static elimination units 30 are discretely provided in the main scanning direction S1. In the example shown in FIG. 13B, the circular static elimination portions 30 are discretely provided in the main scanning direction S1. In the example shown in FIG. 13C, the circular static elimination portion 30 is provided between the heat generating region 21 and the sealing body 26 and discretely provided in the main scanning direction S1. When the static elimination unit 30 is provided between the heat generating region 21 and the sealing body 26, it is preferable to extend a lead wire from the common electrode 19 between the heat generating region 21 and the sealing body 26.

Although the case where the glaze layer 17 is flat has been described, a protruding portion may be provided in the glaze layer. FIG. 14 is a cross-sectional view showing a main part of a thermal print head having a glaze layer provided with a protruding portion.

As shown in FIG. 14, a glaze layer 17 having a protruding portion 17a is provided on the support substrate 16. The projecting portion 17a is slightly closer to the direction opposite to the sub-scanning than the central portion in the sub-scanning direction S2, and extends along the main scanning direction S1. A plurality of heat generating resistors 18, common electrodes 19 and individual electrodes 20 are provided on one surface of the glaze layer 17, and a protective film 22 covering the plurality of heat generating resistors 18, common electrodes 19 and individual electrodes 20 is provided. This is the same as the thermal print head 10 shown in FIG.

The difference is that the portion of the protective film 22 that covers the heat generating resistor 18 also has a convex portion 22b that follows the protruding portion 17a. When the glaze layer has a protruding portion 17a and a convex portion 22b is formed on the protective film 22, the adhesion between the medium 37 and the protective film 22 is improved without increasing the platen pressure of the platen roller 56. However, the frictional force between the medium 37 and the protective film 22 increases.

The static elimination unit 30 of the present embodiment can also be provided in this type of thermal print head.

The heat generating element (glaze layer) includes a thin film type heat generating element formed by using thin film forming technology such as vacuum deposition, CVD, and sputtering and a photoetching method, and a thick film forming technology by printing and firing such as screen printing. There is a thick film type heat generating element formed by using. The heat generating element used in the present embodiment may be formed by any method.

A method of forming the stepped opening 34 by slimming a resist film having a pattern corresponding to the first opening 34a and converting it into a resist film having a pattern corresponding to the second opening can also be considered. ..

Specifically, a resist film having a pattern corresponding to the first opening 34a is formed on the second protective layer 34, and the second protective layer 32 to the first protective layer 31 are etched by the RIE method to expose the common electrode 19. The first opening 34a is formed. The resist film is slimmed to convert the pattern corresponding to the first opening 34a into a pattern corresponding to the second opening 34b larger than the first opening 34a. The second protective layer 34 is etched using a resist having a pattern corresponding to the second opening 34b as a mask to form the second opening 34b. Etching is stopped near the boundary between the second protective layer 32 and the first protective layer 31.

In the static elimination unit 30, the case where the highly conductive third protective layer 33 is electrically connected to the common electrode 19 and the common electrode 19 is connected to the power supply 36 via the resistor 35 has been described. The layer 33 may be connected to a wiring having a reference potential GND.

In that case, for example, a dummy electrode having a pattern isolated from the common electrode 19 may be provided on the glaze layer 17 or the support substrate 16. The third protective layer 33 is connected to a dummy electrode, and the dummy electrode is connected to a wiring having a reference potential GND. Further, the dummy electrode can be connected not only to the wiring having the reference potential GND but also to the wiring having an arbitrary potential other than the power supply 36.

(Embodiment 2)
The thermal printer according to this embodiment will be described. FIG. 15 is a cross-sectional view showing the thermal printer of this embodiment.

As shown in FIG. 15, the thermal printer 70 of the present embodiment uses the thermal print head 10 having the static elimination unit 30 shown in FIG. The thermal printer 70 includes a platen roller 71. The platen roller 71 is arranged so that its side surface is in contact with a heat generation region (a band-shaped region in which a plurality of heat generation resistors are arranged) 21 with the main scanning direction S1 as an axis, and the platen roller 71 is rotatably provided around the shaft 72. Has been done.

The thermal printer 70 moves the thermal paper 73 inserted between the platen roller 71 and the heat generating region 21 in the sub-scanning direction S2 perpendicular to the main scanning direction S1 by the rotation of the platen roller 71. A desired image is formed by selectively generating heat from the plurality of heat generating resistors 18 with the movement of the thermal paper 73.

The platen roller 71 presses the thermal paper 73 against the protective film 22 that covers the heat generating resistors 18 while rotating when the plurality of heat generating resistors 18 are selectively generated. The thermal paper 73 is rubbed against the protective film 22. As a result, the thermal paper 73 is charged.

As described above, when the electric charge charged on the thermal paper 73 is discharged to the thermal print head 10, the electric charge is rapidly discharged through the static elimination unit 30, so that damage to the thermal print head 10 is prevented.

Using the thermal printer 70, printing was continuously performed on the A4 size thermal paper 73, and the durability test of the thermal print head 10 was performed. As a result, no damage to the thermal print head 10 was observed even after printing 20000 sheets. Damage to the thermal print head 10 can be determined by, for example, taking out the thermal print head 10 from the thermal printer 70 and visually observing the presence or absence of discharge marks, particularly the presence or absence of damage to the protective film 22 and the heat generating resistor 18.

Therefore, it is possible to prevent damage due to discharge of the electric charge charged in the medium and obtain a thermal printer 70 using the thermal print head 10.

As described above, since the thermal printer 70 of the present embodiment uses the thermal print head 10 having the static elimination unit 30, it is possible to obtain a thermal printer in which damage due to discharge of the electric charge charged in the medium is prevented. ..

Although some embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

The configuration described in the following appendix can be considered.
(Appendix 1) The thermal printhead according to claim 5, wherein the first electrode is connected to any of the power sources at least via a reference potential line and a resistor.

(Appendix 2) A support substrate, a heat generating resistor arranged on the support substrate, a first electrode and a second electrode provided on the heat generating resistor for supplying power to the heat generating resistor, and the heat generation. An insulating first protective layer, a second protective layer having first conductivity, which are provided on the resistor, the first electrode, and the second electrode, and a second layer having higher conductivity than the first conductivity. A protective film in which two conductive third protective layers are laminated in this order is provided, and the protective film has a stepped shape from the second protective layer to the first protective layer to expose the first electrode. A thermal printer comprising the opening, the third protective layer being in contact with the first electrode exposed in the opening along the inner surface of the opening.

(Appendix 3) Support board and
The heat-generating resistor arranged on the support substrate and
A first electrode and a second electrode provided on the heat generating resistor and for supplying power to the heat generating resistor, and
A protective film provided on the heat generating resistor, the first electrode, and the second electrode, in which an insulating first protective layer and a conductive second protective layer are laminated in this order.
Equipped with
The first protective layer has an opening that exposes the first electrode, and the second protective layer is a thermal print head that contacts the first electrode exposed to the opening along the inner surface of the opening.

(Appendix 4) The thermal print head according to claim 1, wherein the opening has a rectangular shape, a circular shape, or a polygonal shape in a plan view.

10 Thermal printed head 11 Head unit 12 Heat dissipation plate 13 Head board 14 Circuit board 15 Drive IC
16 Support substrate 17 Glaze layer 17a Projective part 18 Heat-generating resistor 19 Common electrode 20 Individual electrode 21 Heat-generating area 22 Protective film 22b Convex part 23 Adhesive 24, 25, 44 Bonding wire 26 Sealing body 30 Static elimination part 31 First protection Layer 32 Second protective layer 32a Insulating layer 32b Conductive layer 33 Third protective layer 34 Openings 34a, 34b First and second openings 35 Resistance 36 Power supply 37 Medium 38 Charge 40 Protective film 41, 42 Conductive agent 43 Bump ball 50 Resistive film 52 Aluminum film 54 Capacitor 55 Connector 71 Platen roller 70 Thermal printer 72 Axis 73 Thermal paper S1 Main scanning direction S2 Sub scanning direction

Claims (7)

A step of forming a heat generating resistor on a glaze layer provided on a support substrate and forming a first electrode and a second electrode for supplying power to the heat generating resistor.
A step of sequentially forming an insulating first protective layer and a first conductive second protective layer on the heat generating resistor, the first electrode, and the second electrode.
A step of forming a stepped opening that exposes the first electrode from the second protective layer to the first protective layer, and
Forming a third protective layer in contact with the first having a higher second conductivity than conductive, the first electrode before SL along the inner surface of the second protective layer and said opening,
A method for manufacturing a thermal print head. In the step of forming the stepped opening, a second opening for exposing the first protective layer is formed in the second protective layer, the first electrode is exposed to the exposed first protective layer, and the first electrode is exposed. The method for manufacturing a thermal printhead according to claim 1, wherein a first opening smaller than two openings is formed. The second opening, the first resist that have a pattern corresponding to the second opening is formed in the second protective layer, the second protective layer is formed by etching the first resist as a mask, In the first opening, a second resist is embedded in the second opening, a pattern corresponding to the first opening is formed in the second resist, and the first protective layer is etched using the second resist as a mask. The method for manufacturing a thermal print head according to claim 2, wherein the thermal print head is formed. According to claim 1, the first protective layer is formed by a chemical vapor deposition method or a sputtering method, the second protective layer is formed by a chemical vapor deposition method, and the third protective layer is formed by a sputtering method. The method of manufacturing the thermal printhead described. Support board and
The heat-generating resistor arranged on the support substrate and
A first electrode and a second electrode provided on the heat generating resistor and for supplying power to the heat generating resistor, and
From the heat generating resistor, the first electrode, the insulating first protective layer provided on the second electrode, the second protective layer having the first conductivity, and the first conductivity. A protective film in which a third protective layer having a high second conductivity is laminated in this order, and
Equipped with
The protective film is provided with a stepped opening extending from the second protective layer to the first protective layer and exposing the first electrode, and the third protective layer is formed along the inner surface of the opening. A thermal print head in contact with the first electrode exposed to the surface. The thermal print according to claim 5, wherein the stepped opening has a first opening provided in the first protective layer and a second opening provided in the second protective layer and larger than the first opening. head. The fifth aspect of claim 5, wherein the second protective layer has an insulating layer in contact with the first protective layer and a conductive layer in contact with the third protective layer, and the conductive layer is thicker than the insulating layer. Thermal print head.