Capacitive input device and method for manufacturing same

Abstract

The purpose of the present invention is to improve the freedom of decoration by light transmission in a capacitive input device in which a touch sensor is operated via a physical switch, and a method for manufacturing the same. The present invention provides a capacitive input device comprising: an operation panel (10); a physical switch (30) having an operation element (key cap 31); a sensor sheet (20) on which a sensor electrode (22) is formed; and a rubber member (rubber dome 34) interposed between the key cap (31) and the sensor sheet (20). A base material sheet (21) and the sensor electrode (22) of the sensor sheet (20), the rubber dome (34), and the key cap (31) are each light-transmissive. On a surface (34a) of the rubber dome (34) opposing the sensor electrode (22), a transparent electrode cover layer (37) is formed. The transparent electrode cover layer (37) is light-transmissive and changes the capacitance of the sensor electrode (22) by moving toward and away from the sensor electrode (22) in accordance with the actuation of the key cap (31).

Description

Capacitive input device and manufacturing method thereof

[0001] The present invention relates to a capacitive input device and a method for manufacturing the same.

[0002] In various fields, such as in-vehicle electronic devices, capacitive input devices equipped with touch sensors that detect touch operations on an operation surface from changes in capacitance due to contact or proximity of a finger to the operation surface are used. Such touch sensors are implemented by attaching a sensor sheet, which has sensor electrodes provided on a flexible base sheet made of resin, to the back side (control board side) of an operation panel. Touch sensors made of flexible printed circuit boards are typically attached to the board side of a decorated resin panel facing the board, and detect input when the inputter touches the resin panel.

[0003] Operation panels often include physical switches, such as dial switches and physical switches (including rubber domes), as easy-to-use switches (see, for example, Patent Documents 1 and 2). However, because such physical switches use a different detection method than capacitive touch sensors, mounting them on the same control board complicates the design. While the touch sensors and other physical switches are typically implemented using different detection methods, if they can be operated using the same method, such as a capacitive detection method, they can be formed as a combined switch on a flexible printed circuit board using the same method, which is rational because they can be processed in the same way using the same IC. Furthermore, because flexible printed circuit boards typically use PET film, transparent electrodes can be used for the touch electrodes, allowing light from a backlight to pass through. This board can be attached to a decorative panel or the like, and the operation points can be clearly indicated (illuminated) by light from a light source such as an LED.

[0004] However, when a touch sensor and a physical switch are combined on a flexible printed circuit board, the configuration of the physical switch tends to block the light from the light source, so it was necessary to either place the light source in a different location to illuminate the operating point, or to give up on giving the physical switch a light-transmitting function in the first place.

[0005] JP 2017-162749 A JP 2016-115401 A

[0006] The present invention has been made in consideration of the above-mentioned situation, and aims to improve the freedom of decoration through light transmission in a capacitive input device that operates a touch sensor via a physical switch and in a manufacturing method thereof.

[0007] The present invention has the following aspects: [1] A capacitance-type input device comprising: an operation panel; a physical switch provided on the operation panel and having an operator that is operated from the front side of the operation panel to activate; a sensor sheet attached to the back side of the operation panel and formed with a sensor electrode that detects the actuation of the operator by a change in capacitance; and a rubber member interposed between the operator and the sensor sheet, wherein the base sheet of the sensor sheet, the sensor electrode, the rubber member, and the operator are all optically transparent, and a transparent electrode cover layer that moves toward and away from the sensor electrode in response to actuation of the operator and changes the capacitance of the sensor electrode and that is optically transparent is formed on a surface of the rubber member facing the sensor electrode. [2] The transparent electrode cover layer is formed on an inner surface of the rubber member that includes the opposing surface, and circuit wiring including sensor wiring connected to the sensor electrode is formed on the sensor sheet, and the transparent electrode cover layer is connected to ground wiring included in the circuit wiring. [3] A capacitive input device according to [2], wherein a protective layer having optical transparency is formed on the transparent electrode cover layer. [4] A method for manufacturing a capacitive input device comprising: an operation panel; a physical switch provided on the operation panel and having an operator that is operated from the front side of the operation panel to be activated; a sensor sheet attached to the back side of the operation panel and having a sensor electrode formed thereon that detects the actuation of the operator by a change in capacitance; and a rubber member interposed between the operator and the sensor sheet, wherein a base sheet of the sensor sheet, the sensor electrode, the rubber member, and the operator each have optical transparency, wherein a light-irradiation type surface modification is performed on an inner surface of the rubber member including a surface facing the sensor electrode, and a light-transmitting transparent electrode cover layer is formed on a surface-modified portion of the inner surface including the facing surface, and a portion of the transparent electrode cover layer formed on the facing surface approaches and moves away from the sensor electrode in response to an operation of the operator, thereby changing the capacitance.

[0008] According to the present invention, in a capacitive input device in which a touch sensor is operated via a physical switch and in a manufacturing method thereof, the degree of freedom in decoration by light transmission can be improved.

[0009] It is a cross-sectional view along the thickness direction of the electrostatic capacitance type input device in an embodiment of the present invention. It is an enlarged view of a main part of FIG. It is a plan view of the periphery of the sensor electrode of the sensor sheet. It is an explanatory view showing a process of forming a transparent electrode cover layer inside a rubber dome. It is an explanatory view showing a process of forming a protective layer on the transparent electrode cover layer.

[0010] An embodiment of a capacitance-type input device according to the present invention will be described in detail below with reference to FIGS. 1 to 5. Note that, for ease of understanding, the drawings used in the following description may show characteristic portions enlarged, and dimensional proportions may differ from those of the actual device. Furthermore, the materials, dimensions, and other elements exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate modifications may be made without departing from the spirit of the present invention. In the following description, the thickness direction of the control board 40, operation panel, and sensor sheet 20, which are parallel to each other in the capacitance-type input device, is indicated by an arrow Dt. For convenience of explanation, one side of the thickness direction Dt is designated as the upper side (arrow Up) and the other side of the thickness direction Dt is designated as the lower side (arrow Lo), but this arrangement is not limited thereto.

[0011] FIG. 1 is a cross-sectional view of a capacitance-type input device 1 according to an embodiment of the present invention taken along the thickness direction Dt. FIG. 2 is an enlarged view of a main portion of FIG. 1. FIG. 3 is a plan view of the sensor electrode and its surroundings on a sensor sheet. The capacitance-type input device 1 is used, for example, in various home appliances, portable devices, and on-board devices for automobiles. As shown in FIGS. 1 and 2, the capacitance-type input device 1 is implemented by superimposing a keycap-type (push button-type) physical switch 30 on a sensor sheet 20 constituting a capacitance-type touch sensor. The capacitance-type input device 1 is configured as a switch-combined sensor sheet.

[0012] The capacitance-type input device 1 includes an operation panel 10, a physical switch 30 having an operator (keycap 31 (push button) in this embodiment) that is operated by a user from the front surface 10a side of the operation panel 10, a sensor sheet 20 attached to the back surface 10b side of the operation panel 10 and having formed thereon sensor electrodes 22 that detect pressing operations on the keycap 31 by changes in capacitance, and a rubber dome (rubber member) 34 interposed between the keycap 31 and the sensor sheet 20. A control board 40 is disposed on the back surface 10b side of the operation panel 10 at a distance from the operation panel 10.

[0013] The operation panel 10 has an opening 10c for arranging the physical switch 30. A keycap 31 is fitted into the opening 10c so as to be movable in the thickness direction Dt. A reinforcing plate 11 for reinforcing the sensor sheet 20 is provided on the rear surface of the sensor sheet 20 within a specified range including the opening 10c.

[0014] The operation panel 10 can be, for example, a resin plate made of polycarbonate (PC), acrylic resin, or the like, or a glass plate. The reinforcing plate 11 is not particularly limited, but is preferably a resin plate similar to the operation panel 10 in terms of light weight and ease of processing.

[0015] The physical switch 30 includes a keycap 31 that is supported by the operation panel 10 and can press a rubber dome 34. The keycap 31 is cylindrical with a bottom that opens toward the rubber dome 34. A protruding block 33 that protrudes toward the rubber dome 34 is formed on an inner surface 32b (lower surface, back surface) of a bottom 32 of the keycap 31. An outer surface 32a (upper surface, front surface) of the bottom 32 of the keycap 31 serves as an operating point 32a that is pressed by the user.

[0016] When the keycap 31 of the physical switch 30 is pressed, the keycap 31 is displaced toward the rear surface 10b of the operation panel 10 while elastically deforming the rubber dome 34. When the pressure on the keycap 31 is released, the rubber dome 34 returns to its original shape, allowing the keycap 31 to return to its original position.

[0017] The rubber dome 34 is disposed to cover the sensor electrode 22 from the surface 10a side, forming a space above the sensor electrode 22 that is open downward (toward the sensor electrode 22). The rubber dome 34 includes a cylindrical operation block 35 that is pressed by the protruding block 33 in the keycap 31, and a hollow, truncated conical skirt piece 36 that extends while gradually widening from the lower circumferential surface of the operation block 35. The lower end surface of the operation block 35 is an opposing surface 34a that faces the sensor electrode 22 in the thickness direction Dt. The lower end 36a of the skirt piece 36 is fixed to the surface of the base sheet 21 around the sensor electrode 22. When the operation block 35 is pressed, the skirt piece 36 elastically deforms to bend.

[0018] A transparent electrode cover layer 37 is formed on an inner surface 34b of the rubber dome 34 that faces the surface of the base sheet 21. A portion 38 of the transparent electrode cover layer 37 that covers the opposing surface 34a changes the capacitance of the sensor electrode 22 by moving toward and away from the sensor electrode 22.

[0019] Pressing the keycap 31 presses the rubber dome 34, causing the transparent electrode cover layer 37 inside the rubber dome 34 to approach the sensor electrode 22, changing the capacitance of the sensor electrode 22. An integrated circuit (IC) on the control board 40 detects this change in capacitance, thereby realizing input by the keycap 31 (detection of the pressing operation). When the pressing operation of the keycap 31 is released, the rubber dome 34 returns to its original shape, causing the transparent electrode cover layer 37 to move away from the sensor electrode 22, changing the capacitance of the sensor electrode 22. The IC on the control board 40 detects this change in capacitance, thereby detecting the release of the keycap 31.

[0020] The sensor electrode 22 replaces the contacts of a conventional push button and detects the on / off state of the physical switch 30 from changes in capacitance. By limiting the amount of depression of the keycap 31, contact between the rubber dome 34 and the sensor sheet 20 is avoided, and scraping and scratching of the transparent electrode cover layer 37 is suppressed.

[0021] The transparent electrode cover layer 37 is formed on the entire inner surface 34b of the rubber dome 34, and at least a portion of it extends to the lower end 36a of the skirt piece 36. At the lower end 36a of the skirt piece 36, the transparent electrode cover layer 37 is connected to the ground wiring 25b (see FIG. 3) included in the circuit wiring 25 of the sensor sheet 20. This allows the transparent electrode cover layer 37 to also function as a shield layer against noise, thereby improving the noise resistance and switch sensitivity of the input device 1.

[0022] A light-transmitting protective layer 39 is formed on the surface of the transparent electrode cover layer 37, except for the connection portion with the ground wiring 25b (the portion formed on the lower end 36a of the skirt piece 36). This prevents damage to the transparent electrode cover layer 37 due to contact with the sensor sheet 20, even when the transparent electrode cover layer 37 is formed thin to increase light transmittance.

[0023] The material of the rubber dome 34 is not particularly limited, and examples thereof include elastomers such as silicone rubber, fluororubber, urethane rubber, and ethylene propylene diene rubber (EPDM). Silicone rubber is preferred as the material of the rubber dome 34 because of its excellent light transmittance, temperature characteristics, environmental characteristics, electrical characteristics, and compression characteristics.

[0024] <Sensor sheet 20> The sensor sheet 20 includes a flexible printed circuit board (base sheet, sheet body) 21 and a sensor electrode 22 as a transparent electrode formed on the flexible printed circuit board 21. The sensor electrode 22 is electrically connected to an external connection terminal (not shown) by circuit wiring 25 formed on the flexible circuit board 21. The circuit wiring 25 includes a sensor wiring 25a connected to the sensor electrode 22 and a ground wiring 25b.

[0025] The resin constituting the base sheet 21 may be any resin that can be used to form a flexible and transparent base sheet 21, and examples of such resins include polyester (such as polyethylene terephthalate (PET)), PC, acrylic resin, cyclic polyolefin resin, and triacetyl cellulose. The base sheet 21 may be made of one type of resin or two or more types of resins.

[0026] The average thickness of the base sheet 21 is preferably 10 to 250 μm, and more preferably 25 to 188 μm. If the average thickness of the base sheet 21 is equal to or greater than the lower limit of the above range, sufficient strength is easily ensured. If the average thickness of the base sheet 21 is equal to or less than the upper limit of the above range, the sensor sheet 20 can be easily made thinner.

[0027] The sensor electrode 22 is an electrode for detecting a touch operation on the surface 10a of the operation panel 10 by a change in capacitance. In the embodiment, one sensor electrode 22 (and physical switch 30) is illustrated as an example, but one capacitance-type input device 1 may be provided with a plurality of sensor electrodes 22 (and physical switches 30).

[0028] A specified area of ​​the sensor sheet 20, including the portion where the sensor electrodes 22 are provided, is attached to the rear surface 10b of the operation panel 10. The sensor electrodes 22 are electrically connected to the control board 40 via circuit wiring 25 and the like. By attaching the sensor sheet 20 to the operation panel 10, the physical switches 30 (keycaps 31) can be arranged at a position away from the control board 40.

[0029] The sensor electrode 22 is an electrode for detecting a touch operation on the surface 10a of the operation panel 10 by a change in capacitance. When viewed from the thickness direction Dt, the sensor electrode 22 is disposed inside the opening 10c in which the physical switch 30 is disposed in the operation panel 10. In this example, the shape of the sensor electrode 22 in a plan view is circular, but is not limited thereto and may be rectangular, triangular, or the like.

[0030] A known electrode can be used as the sensor electrode 22, and may be of a self-capacitance type or a mutual capacitance type. The form of the mutual capacitance type sensor electrode 22 is not particularly limited, and examples thereof include a solid electrode and a comb-tooth electrode. The form of the self-capacitance type sensor electrode 22 is not particularly limited, and examples thereof include a solid electrode and a diamond pattern.

[0031] For example, a transparent conductive film can be used as the sensor electrode 22. Examples of transparent conductive films include a film containing a conductive polymer, a film containing conductive nanowires, a film containing metal particles or conductive metal oxide particles, a film containing carbon, and a metal vapor deposition film formed by a metal vapor deposition method, and a film containing a conductive polymer is preferred because of its excellent bending resistance.

[0032] Examples of conductive polymers include polythiophene, polypyrrole, and polyaniline, with polythiophene being preferred, and poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid being particularly preferred. Examples of conductive nanowires include silver nanowires, gold nanowires, and carbon nanotubes. Examples of metal particles include particles of metals such as silver, copper, and gold. Examples of conductive metal oxide particles include particles of indium-doped tin oxide. Examples of carbon include carbon black and graphite. Examples of metals that form the metal vapor deposition film include copper, aluminum, nickel, chromium, zinc, and gold, with copper being preferred.

[0033] The sensor electrode 22 is not limited to a transparent conductive film, and may be an electrode formed of silver paste, carbon paste, or the like. The average thickness of the sensor electrode 22 can be set appropriately depending on the material, and for example, in the case of a film containing a conductive polymer, the average thickness is preferably 0.1 to 0.5 μm, and more preferably 0.1 to 0.2 μm. The sensor electrode 22 may be disposed on the upper surface of the base sheet 21 on the operation panel 10 side, or on the lower surface on the control board 40 side.

[0034] The material of the circuit wiring 25 is not particularly limited, and may be, for example, the same material as the sensor electrode 22, preferably silver paste. The average thickness of the circuit wiring 25 is not limited, but may be approximately the same as the average thickness of the sensor electrode 22, for example.

[0035] The method for attaching the sensor sheet 20 to the operation panel 10 is not particularly limited, and an example of such a method is to form an adhesive layer on the portion of the sensor sheet 20 that will be attached to the operation panel 10, and then attach the sensor sheet 20 to the operation panel 10 via this adhesive layer. The same method can be used to attach the reinforcing plate 11 to the sensor sheet 20 or the operation panel 10.

[0036] Examples of materials for the adhesive layer include known curing adhesives (liquid adhesives before bonding) or pressure-sensitive adhesives (gel-like pressure-sensitive adhesives before bonding). The adhesive layer may also be a substrate-type adhesive layer in which an adhesive or pressure-sensitive adhesive is disposed on both sides of a substrate, or a known double-sided tape. Examples of adhesives and pressure-sensitive adhesives include acrylic resins, urethane resins, and ethylene-vinyl acetate copolymers. The curing adhesive may be a solvent-type adhesive containing a solvent that volatilizes upon curing, or a hot-melt type adhesive. The average thickness of the adhesive layer is not particularly limited and can be, for example, 1 to 100 μm.

[0037] <Decoration by Light Transmission> An LED is mounted on the control board 40 as a light source 41 that illuminates the operation point 32a (surface of the keycap 31). The light source 41 is disposed at a position overlapping the rubber dome 34 and the keycap 31 when viewed from the thickness direction Dt. The rubber dome 34 and the keycap 31 have, for example, a circular shape when viewed from the thickness direction Dt. The light source 41 is disposed at the center of the rubber dome 34 and the keycap 31 when viewed from the thickness direction Dt.

[0038] The flexible substrate 21 and the sensor electrode 22 are each optically transparent. The rubber dome 34 and the keycap 31 each have a light-transmitting portion 34c, 31c, which is optically transparent, at least in a portion overlapping the sensor electrode 22 in the thickness direction Dt. The light-transmitting portion 31c of the keycap 31 reaches the surface 32a of the keycap 31 and emits light, for example, to indicate a character or symbol indicating an operation position 32a. In this way, light emitted by the LED serving as the light source 41 is transmitted to the surface 32a of the keycap 31, allowing the surface 32a of the keycap 31 to be decorated by the light transmission.

[0039] The silicone rubber that forms the rubber dome 34 is ideal for covering the sensor electrode 22 in terms of its force-stroke (FS) characteristics and durability, and although some materials are light-transmitting, the properties of rubber make it difficult to form the transparent electrode cover layer 37 on the rubber dome 34 as is. In this embodiment, the inner surface 34b of the rubber dome 34 is surface-modified to selectively improve hydrophilicity, making it possible to directly provide the transparent electrode cover layer 37.

[0040] The formation of the transparent electrode cover layer 37 inside the rubber dome 34 will be described with reference to Fig. 4. Fig. 4 is an explanatory diagram showing the process of forming the transparent electrode cover layer 37 inside the rubber dome 34. First, the inner surface 34b of the rubber dome 34 made of silicone rubber, which has been produced by press molding or the like, is irradiated with excimer, plasma, or the like from irradiation device A to perform light irradiation type surface modification (see Fig. 4(a)).

[0041] Next, the rubber dome 34 is dipped into a liquid of, for example, PEDOT / PSS (a dispersion of polyethylenedioxythiophene and polystyrene sulfonic acid) (see FIG. 4(b)). Reference symbol B in the figure indicates a dipping tank. This forms a transparent electrode cover layer 37 on the inner surface 34b of the rubber dome 34 (see FIG. 4(c)). The transparent electrode cover layer 37 may be formed using a method such as inkjet printing. Because the silicone rubber repels PEDOT / PSS in areas other than those where the surface has been modified, the transparent electrode cover layer 37 can be formed selectively on the rubber dome 34 (limited to the areas where the surface has been modified).

[0042] Addition of the protective layer 39 to the transparent electrode cover layer 37 will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram showing the process of forming the transparent protective layer 39 on the transparent electrode cover layer 37. The protective layer 39 is formed by applying ink to the inner surface 34b of the rubber dome 34 using, for example, an ink discharge nozzle C (see Figs. 5(a) and 5(b)). The protective layer 39 can be formed by various means such as inkjet printing or spraying.

[0043] The transparent electrode cover layer 37 has high optical transparency and preferably has a thickness of 10 to 250 μm, and particularly preferably 50 μm or less. A thin transparent electrode cover layer 37 is prone to contact with its surroundings each time it is used as a button, and is prone to deterioration such as scraping and scratches. In this embodiment, the entire transparent electrode cover layer 37 (except for the portion connected to the ground wiring 25b) is covered with a protective layer 39 of approximately 10 to 20 μm to protect it from contact. The protective layer 39 is not particularly limited, and may be, for example, a layer of the same resin as that exemplified for the base sheet 21.

[0044] In the capacitance-type input device 1 of the embodiment, a sensor sheet 20 is formed by forming circuit wiring 25 and sensor electrodes 22 on a flexible base sheet 21. An operator (keycap 31) of a physical switch 30 is arranged on one side of the sensor sheet 20 in the thickness direction Dt, with a rubber dome 34 sandwiched between them. When a user operates the keycap 31 to activate it (press it toward the other side in the thickness direction Dt), the rubber dome 34 elastically deforms, and the transparent electrode cover layer 37 inside the rubber dome 34 approaches the sensor electrode 22, causing an electrical change.

[0045] After light irradiation-type surface modification, a transparent electrode cover layer 37 is formed inside the rubber dome 34 by coating. The base sheet 21, sensor electrode 22, rubber dome 34, operator, and transparent electrode cover layer 37 are optically transparent. By irradiating the sensor electrode 22 side with a light source 41 arranged on the back side of the sensor sheet 20 (the other side in the thickness direction Dt, the opposite side from the physical switch 30), it is possible to illuminate the surface of the keycap 31 (operation location 32 a).

[0046] According to the embodiment, it is possible to provide a capacitance-type input device 1 that has both an easy-to-use physical switch 30 and a capacitance-type touch sensor with a simple configuration, and that can decorate the key cap 31 with light transmission.

[0047] As described above, the capacitance-type input device 1 of the embodiment comprises an operation panel 10, a physical switch 30 provided on the operation panel 10 and having an operator (keycap 31) that is operated from the front surface 10a of the operation panel 10, a sensor sheet 20 attached to the back surface 10b of the operation panel 10 and having a sensor electrode 22 formed thereon that detects the operation of the keycap 31 by a change in capacitance, and a rubber member (rubber dome 34) interposed between the keycap 31 and the sensor sheet 20, and the base sheet 21 and sensor electrode 22 of the sensor sheet 20, the rubber dome 34, and the keycap 31 are all optically transparent, and a transparent electrode cover layer 37 that moves toward and away from the sensor electrode 22 in accordance with the operation of the keycap 31 and changes the capacitance of the sensor electrode 22 and is optically transparent is formed on the surface 34a of the rubber dome 34 facing the sensor electrode 22.

[0048] According to this configuration, the base sheet 21, sensor electrodes 22, keycaps 31, rubber domes 34, and transparent electrode cover layer 37 of the sensor sheet 20 are all optically transparent. When a light source 41 is placed on the back side of the sensor sheet 20 and irradiates the physical switch 30, the irradiated light passes through the sensor sheet 20, rubber domes 34, and physical switch 30, causing the surface of the keycap 31 (operation location 32a) to glow. In other words, the capacitive input device 1 equipped with the physical switch 30 can be decorated by light transmission. By using a capacitive method for input via the keycap 31, which is commonly used in touch sensors, design flexibility can be improved and costs can be reduced. Because the contacts of a capacitive button switch are non-contact, wear on the contacts can be prevented, preventing button malfunction. This configuration allows for pressure detection and light transmission, which are not possible with contact-type button switches.

[0049] In the above-described capacitance-type input device 1, a transparent electrode cover layer 37 is formed on the inner surface 34b of the rubber dome 34, including the opposing surface 34a. The sensor sheet 20 is formed with circuit wiring 25, including sensor wiring connected to the sensor electrodes 22, and the transparent electrode cover layer 37 is connected to ground wiring 25b included in the circuit wiring 25. With this configuration, the transparent electrode cover layer 37, which covers the entire inner surface 34b of the rubber dome 34, is connected to the ground wiring 25b of the sensor sheet 20, so that the transparent electrode cover layer 37 also serves as a shielding layer against external noise. This improves the signal-to-noise ratio (SNR) of the sensor electrode 22 directly below the rubber dome 34, thereby enabling improvements in noise resistance and switch sensitivity.

[0050] In the above-described capacitance-type input device 1, a light-transmitting protective layer 39 is formed on the transparent electrode cover layer 37. According to this configuration, by covering the transparent electrode cover layer 37 with the protective layer 39, even when the transparent electrode cover layer 37 is formed thin to provide high light transmittance, scraping and scratches on the transparent electrode cover layer 37 can be suppressed.

[0051] The manufacturing method of the capacitance type input device 1 includes an operation panel 10, a physical switch 30 provided on the operation panel 10 and having an operator (keycap 31) that is operated from the front surface 10a side of the operation panel 10, a sensor sheet 20 attached to the back surface 10b side of the operation panel 10 and having a sensor electrode 22 formed thereon that detects the operation of the keycap 31 by a change in capacitance, and a rubber member (rubber dome 34) interposed between the keycap 31 and the sensor sheet 20, wherein the base sheet 21 and the sensor electrode 22 of the sensor sheet 20, the rubber dome 34, and the keycap 31 are each optically transparent, and a light-irradiation type surface modification is performed on the inner surface 34b of the rubber dome 34, including the surface 34a facing the sensor electrode 22, and a light-transmitting transparent electrode cover layer 37 is formed on the surface-modified portion of the inner surface 34b including the facing surface 34a, and a portion 38 formed on the facing surface 34a of the transparent electrode cover layer 37 approaches or moves away from the sensor electrode 22 in response to operation on the keycap 31, thereby changing the capacitance. According to this configuration, by performing light irradiation-type surface modification on the inner surface 34b of the rubber dome 34, the inner surface 34b of the rubber dome 34 can be made hydrophilic, allowing the transparent electrode cover layer 37 to be provided. Silicone rubber, which forms the rubber dome 34, is an ideal material for covering the sensor electrode 22 in terms of FS characteristics and durability, and there are also light-transmitting materials, but due to the properties of rubber, it is difficult to form the transparent electrode cover layer 37 using this material as is. In contrast, by selectively improving the hydrophilicity by surface modifying the inner surface 34b of the rubber dome 34, the transparent electrode cover layer 37 can be provided directly.

[0052] The present invention is not limited to the above-described embodiments. For example, in the embodiments, a push button is used as an example of an operator for a physical switch, but the present invention is not limited to this. For example, the physical switch may have an operator that requires another action, such as a rotary dial. The configuration in the above-described embodiment is an example of the present invention, and various modifications are possible without departing from the spirit and scope of the present invention.

[0053] REFERENCE SIGNS LIST 1 Capacitive input device 10 Operation panel 10a Front surface 10b Back surface 20 Sensor sheet 21 Base sheet 22 Sensor electrode 25 Circuit wiring 25b Ground wiring 30 Physical switch 31 Keycap (operator) 32a Operation location 34 Rubber dome (rubber member) 34a Opposing surface 34b Inner surface 37 Transparent electrode cover layer 38 Portion formed on opposing surface 39 Protective layer 41 Light source

Claims

1. A capacitance-type input device comprising: an operation panel; a physical switch provided on the operation panel and having an operator that is operated from the front side of the operation panel; a sensor sheet attached to the back side of the operation panel and having a sensor electrode formed thereon that detects the operation of the operator by a change in capacitance; and a rubber member interposed between the operator and the sensor sheet, wherein the base sheet and the sensor electrode of the sensor sheet, the rubber member and the operator are all optically transparent, and a transparent electrode cover layer, which moves toward and away from the sensor electrode in response to the operation of the operator to change the capacitance of the sensor electrode and which is optically transparent, is formed on the surface of the rubber member facing the sensor electrode.

2. A capacitance-type input device as described in claim 1, wherein a transparent electrode cover layer including the transparent electrode cover layer is formed on an inner surface including the opposing surface of the rubber member, the sensor sheet is formed with circuit wiring including sensor wiring connected to the sensor electrode, and the transparent electrode cover layer is connected to ground wiring included in the circuit wiring.

3. The capacitive input device according to claim 2, wherein a protective layer having optical transparency is formed on the transparent electrode cover layer.

4. A method for manufacturing a capacitance-type input device comprising: an operation panel; a physical switch provided on the operation panel and having an operator that is operated from the front side of the operation panel; a sensor sheet attached to the back side of the operation panel and formed with a sensor electrode that detects the operation of the operator by a change in capacitance; and a rubber member interposed between the operator and the sensor sheet, wherein the base sheet of the sensor sheet, the sensor electrode, the rubber member, and the operator are all light-transmitting, the method comprising: performing light-irradiation type surface modification on an inner surface of the rubber member including a surface facing the sensor electrode; forming a transparent electrode cover layer having light transparency on a surface-modified portion of the inner surface including the facing surface; and changing the capacitance by moving a portion of the transparent electrode cover layer formed on the facing surface toward and away from the sensor electrode in response to operation of the operator.

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