Sensor sheet and manufacturing method thereof

Abstract

To provide a sensor sheet capable of being easily manufactured with high degree of freedom in designing, and efficiently illuminating a target design by suppressing light leakage from a part excluding a target illumination region, and a manufacturing method thereof.SOLUTION: A sensor sheet 1 includes: a base material sheet 10; an electrode layer 12 provided on a back face of the base material sheet 10; a core layer 14 and a clad layer 16 provided on a front face of the base material sheet 10; a light diffusion layer 18 provided in the core layer 14; a light source 20; and a cover plate 24. The core layer 14 forms a light guide passage 15 for guiding light from the light source 20 to the light diffusion layer 18. The clad layer 16 is provided in a state of covering the circumference of the core layer 14. The light source 20 is disposed at a side surface side of an end portion of the light guide passage 15. The cover plate 24 is provided at a side opposite to the base material sheet 10 of the clad layer 16 via an adhesive layer 22. In the cover plate 24, a light shielding portion 28 and a light transmitting portion 26 are formed. The light diffusion layer 18 is provided at a position to be overlapped to the light transmitting portion 26 when observed from a thickness direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sensor sheet and a manufacturing method thereof. [Background technology]

[0002] Capacitive sensor sheets, which allow users to input information by touching the screen, are used in electronic devices in various fields, including in-vehicle devices. For example, by attaching a sensor sheet to the back of an operation panel, it is possible to detect touch operations made by users on the operation surface of the operation panel.

[0003] Patent documents 1 and 2 propose providing a light diffusion layer on a sensor sheet, diffusing light from light-emitting elements from the side of the light diffusion layer, and transmitting the light to the operation panel, thereby stably illuminating a design formed on the operation panel for a long period of time. However, such sensor sheets have a problem in that the light diffused by the light diffusion layer leaks to the outside from areas other than the intended illumination area and is attenuated, resulting in low efficiency in illuminating the intended design.

[0004] Patent documents 3 to 5 disclose light guide sheets including a core layer and a clad layer laminated on the core layer. However, the application of sensor sheets to design illumination has not been considered. These light guide sheets have a complex structure because they require the formation of a reflective layer and a void region, and because they use a molded sheet, it is difficult to freely design the core layer, and it is also difficult to illuminate each design separately, making them unsuitable for sensor sheets.

[0005] Patent documents 6 to 9 propose a configuration including a core layer and a clad layer formed by etching as an optical waveguide element (waveguide optical device) used in optical communications, etc. However, the application of sensor sheets to decorative lighting has not been considered. The application of sensor sheets to decorative lighting has problems such as low flexibility, difficulty in incorporating a light diffusion layer, and difficulty in thinning and integrating due to complicated processes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2021-007083 A [Patent Document 2] Patent No. 6562557 [Patent Document 3] JP 2008-251367 A [Patent Document 4] JP 2011-253696 A [Patent Document 5] JP 2011-253697 A [Patent Document 6] Patent No. 2671764 [Patent Document 7] Patent No. 2968508 [Patent Document 8] Patent No. 3665967 [Patent Document 9] Patent No. 4732356 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide a sensor sheet that has a high degree of design freedom, can be easily manufactured, and can efficiently illuminate the desired design by suppressing light leakage from areas other than the desired illumination area, as well as a method for manufacturing the sensor sheet. [Means for solving the problem]

[0008] The present invention includes the following configurations. [1] A base sheet; an electrode layer provided on the back surface of the base sheet; a core layer and a clad layer provided on the front surface of the base sheet; a light diffusing layer provided within the core layer; A light source; A cover plate; the core layer forms a light guide path that guides light from the light source to the light diffusion layer, the clad layer is provided to cover the periphery of the core layer, The light source is disposed on a side surface of an end portion of the light guide path, the cover plate is provided on the clad layer on the opposite side to the base sheet via an adhesive layer; The cover plate is formed with a light-shielding portion and a light-transmitting portion, The light diffusion layer is provided at a position overlapping the light transmitting portion when viewed in the thickness direction of the sensor sheet. [2] The core layer is made of a UV-cured product of at least one material selected from the group consisting of an acrylic resin, a silicone acrylate resin, a urethane acrylate resin, an epoxy acrylate resin, a polyurethane acrylate resin, a methacrylic resin, and a cyanoacrylate resin; The thickness of the core layer is 5 μm or more and 100 μm or less, The sensor sheet according to [1], wherein the core layer has a total light transmittance of 90% or more. [3] The sensor sheet according to [1] or [2], wherein the shape of a cross section of the core layer perpendicular to the light guide path is approximately semicircular, and the angle of the contact portion between the side of the core layer and the front surface of the base sheet or the cladding layer on which the core layer is formed is 30 degrees or more. [4] The sensor sheet according to any one of [1] to [3], wherein the light guide path has a portion curved in an arc shape, and the curved portion has a radius of curvature R of 100 μm or more. [5] The cladding layer is made of a UV-cured product of at least one material selected from the group consisting of an acrylic resin, a methacrylic resin, an epoxy acrylate resin, a polyurethane acrylate resin, a silicone acrylate resin, a urethane acrylate resin, a cyanoacrylate resin, and a vinyl ether resin; The thickness of the cladding layer is 1 μm or more and 30 μm or less, The sensor sheet according to any one of [1] to [4], wherein the cladding layer has a total light transmittance of 90% or more. [6] The sensor sheet according to any one of [1] to [5], wherein the ratio of the distance between an end of the cladding layer and the closest end of the core layer to the end of the cladding layer, when viewed in the thickness direction, to the thickness of the core layer is 1 or more and 100 or less. [7] The adhesive layer is provided so as not to overlap the core layer when viewed in the thickness direction, The sensor sheet according to any one of [1] to [6], wherein a ratio of the shortest distance between the adhesive layer and the core layer as viewed in the thickness direction to the thickness of the adhesive layer is 10 or more. [8] The sensor sheet according to any one of [1] to [7], wherein the reflectance of the base sheet is 90% or more. [9] The sensor sheet according to any one of [1] to [8], wherein a light emission portion of the light source is covered with the same material as the core layer.

[10] A method for producing the sensor sheet according to any one of [1] to [9], A method for manufacturing a sensor sheet includes laminating a first clad layer, the light diffusion layer, the core layer, and a second clad layer in that order on the front surface of the base sheet by mesh screen printing, in which the screen mesh count is 80 mesh or more and 325 mesh or less and the screen mesh is made of polyester, or by metal plate printing, in which the thickness of the metal plate is 50 μm or more and 300 μm or less, to form the clad layer in which the core layer is sandwiched between the first clad layer and the second clad layer. Effect of the Invention

[0009] According to the present invention, there is provided a sensor sheet that has a high degree of design freedom and can be easily manufactured, and that can efficiently illuminate the desired design by suppressing light leakage from areas other than the desired illumination area, and a method for manufacturing the sensor sheet. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a cross-sectional view showing a sensor sheet according to an example of the embodiment. [Diagram 2] 2 is a plan view showing a portion of the sensor sheet in FIG. 1 excluding an adhesive layer and a cover plate. FIG. [Diagram 3]3A is a cross-sectional view showing a base sheet, a core layer, and a clad layer, in which FIG. 3(A) is a cross-sectional view showing an embodiment in which a core layer is provided on the front surface of a first clad layer, and FIG. 3(B) is a cross-sectional view showing an embodiment in which a core layer is provided on the front surface of a base sheet. [Figure 4] 2 is a plan view showing a portion of the sensor sheet in FIG. 1 excluding a cover plate. [Diagram 5] FIG. 11 is a plan view showing a portion of a sensor sheet of another example excluding an adhesive layer and a cover plate. [Figure 6] FIG. 11 is a plan view showing a portion of a sensor sheet of another example excluding a cover plate. [Figure 7] 10 is a cross-sectional view showing an example of an elastic layer used in a Z electrode body, which is an example of an electrode layer. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the present invention, the surface of the sensor sheet facing the operation surface is referred to as the "front surface", and the surface opposite the operation surface is referred to as the "rear surface".

[0012] [Sensor sheet] The sensor sheet according to the embodiment comprises a base sheet, an electrode layer provided on the back surface of the base sheet, a core layer and a clad layer provided on the front surface of the base sheet, a light diffusion layer provided within the core layer, a light source, and a cover plate, wherein the core layer forms a light guide path that guides light from the light source to the light diffusion layer, the clad layer is provided so as to cover the periphery of the core layer, the light source is disposed on the side of the end of the light guide path, the cover plate is provided on the opposite side of the clad layer to the base sheet via an adhesive layer, and a light-shielding portion and a light-transmitting portion are formed in the cover plate, and the light diffusion layer is provided in a position overlapping the light-transmitting portion when viewed from the thickness direction. The sensor sheet of the embodiment can be, for example, a capacitive sensor sheet that detects input in at least one of the plane XY directions, which are the surface directions of the operating surface (front surface) of the cover plate, and the Z direction (thickness direction) perpendicular to the plane XY direction.

[0013] The sensor sheet of the present invention will be described below with reference to the drawings, showing an example. Note that the dimensions of the drawings shown in the following description are merely examples, and the present invention is not necessarily limited thereto, and may be modified as appropriate within the scope of the present invention.

[0014] Fig. 1 is a cross-sectional view showing a sensor sheet 1 according to an example of an embodiment. In Fig. 1, the right-hand direction on the paper surface is the X-direction, the upward direction on the paper surface is the Z-direction, and the depth direction on the paper surface perpendicular to the X-direction and Z-direction is the Y-direction. The sensor sheet 1 according to this embodiment includes a base sheet 10, an electrode layer 12, a core layer 14, a cladding layer 16, a light diffusing layer 18, a light source 20, an adhesive layer 22, and a cover plate 24.

[0015] An electrode layer 12 is provided on the back surface 10b of the base sheet 10, and a core layer 14 and a clad layer 16 are provided on the front surface 10a of the base sheet 10. The core layer 14 forms a light guide path 15 that guides light from the light source 20 to the light diffusion layer 18, and the clad layer 16 is provided so as to cover the periphery of the core layer 14. The light diffusion layer 18 is provided in the core layer 14, and the light source 20 is disposed on the side surface of the end of the light guide path 15 opposite to the light diffusion layer 18. Light emitted from the light source 20 enters the core layer 14 from the side surface of the end of the light guide path 15 and is guided to the light diffusion layer 18 through the light guide path 15.

[0016] The cover plate 24 is provided on the cladding layer 16 on the side opposite the base sheet 10 via an adhesive layer 22 . The cover plate 24 has a light transmitting portion 26 and a light blocking portion 28 formed therein. When viewed from the thickness direction (Z direction), the light diffusion layer 18 is provided at a position overlapping the light transmitting portion 26. That is, the light diffusion layer 18 and the light transmitting portion 26 are disposed at the same positions in the planar XY directions.

[0017] (Base sheet) The base sheet 10 may be transparent or opaque. Examples of materials constituting the base sheet 10 include plastic films and glass plates. Examples of resins constituting the plastic films include polyethylene terephthalate, polycarbonate, polyimide, triacetyl cellulose, cyclic polyolefins, acrylic resins, etc. Among these, polyethylene terephthalate (PET) or polycarbonate is preferred because of its high heat resistance, high dimensional stability, and low cost.

[0018] A metal layer may be provided on the front side of the base sheet 10. Examples of materials for the metal layer include copper, aluminum, silver, etc. The metal layer preferably has light reflectivity, but does not necessarily have light reflectivity.

[0019] The reflectance of the base sheet 10 is preferably 5% or more, and more preferably 10% or more. If the reflectance of the base sheet 10 is equal to or more than the lower limit, the target design can be illuminated more efficiently. The reflectance of the base sheet is the total light reflectance measured in accordance with JIS K7375:2008.

[0020] The shape of the base sheet 10 is not particularly limited and can be appropriately designed depending on the application. The thickness of the base sheet 10 is not particularly limited and can be, for example, 10 to 100 μm.

[0021] (Core layer, clad layer and light diffusion layer) Fig. 2 is a plan view showing a portion of the sensor sheet 1 excluding the adhesive layer 22 and the cover plate 24. In Fig. 2, the right-hand direction on the paper is the X-direction, the upward direction on the paper is the Y-direction, and the direction toward the front of the paper, which is perpendicular to the X-direction and Y-direction, is the Z-direction. 2, the core layer 14 forms a light guide path 15 that guides the light emitted from the light source 20 to the light diffusion layer 18. The core layer 14 is surrounded by a cladding layer 16, which prevents the light passing through the light guide path 15 from leaking midway. 1, the light diffusion layer 18 is provided in the core layer 14 so that the entire periphery is covered by the core layer 14. Light emitted from the light source 20 is guided to the light diffusion layer 18 through the light guide path 15, and is diffused by the light diffusion layer 18. Of the diffused light, the light directed toward the light-transmitting portion 26 of the cover plate 24 transmits through the core layer 14 and the cladding layer 16, and passes through the light-transmitting portion 26, thereby illuminating the desired design.

[0022] 2 shows an example in which light-transmitting sections 26, which are the target illumination regions, are present in three locations on the cover plate 24, and three light diffusion layers 18 are arranged so as to overlap with the light-transmitting sections 26 when viewed from the Z direction, and three light guide paths 15 that guide light from three light sources 20 to the respective light diffusion layers 18 are formed by the core layer 14. In this way, when multiple light diffusion layers 18 are connected to separate light sources 20 by multiple light guide paths 15, it is advantageous in that it becomes possible to illuminate each design with a different light source. The pattern of the light guide path formed by the core layer 14 can be designed appropriately depending on the number and positions of the light sources 20 and the light diffusion layers 18. The light guide path 15 may be formed so that light is guided from one light source 20 to multiple light diffusion layers 18.

[0023] 2 and 3(A), a first clad layer 16A is formed on the front surface 10a of the base sheet 10, a core layer 14 is formed on the front surface of the first clad layer 16A, and a second clad layer 16B is formed so as to cover the periphery of the core layer 14. The clad layer 16 is formed by the first clad layer 16A and the second clad layer 16B which sandwich the core layer 14 from above and below. The embodiment in which a core layer and a clad layer are provided on the front surface of the base sheet is not limited to the embodiment shown in Fig. 2 and Fig. 3(A). For example, as shown in Fig. 3(B), the core layer 14 may be formed directly on the front surface 10a of the base sheet 10, and the clad layer 16 may be formed so as to cover the periphery of the core layer 14. The core layer and the cladding layer are preferably layers formed by mesh screen printing or metal plate printing, since this allows greater freedom in design and allows for easier production.

[0024] 2, a cladding layer 16 is provided on the entire front surface 10a of the base sheet 10 so as to cover the periphery of all of the core layers 14 forming the three light guide paths 15. The manner in which the cladding layer 16 is provided is not limited to the manner shown in FIG. 2, as long as the cladding layer 16 is provided so as to cover the periphery of the core layers 14. For example, as in the example shown in FIG. 5, the cladding layer 16 may be provided in a shape that follows each of the light guide paths 15 formed by the core layers 14 so as to cover the periphery of the core layers 14.

[0025] The constituent material of the core layer 14 is preferably a UV-curable material, but is not limited thereto. Examples of the UV-cured material constituting the core layer 14 include acrylic resin, silicone acrylate resin, urethane acrylate resin, epoxy acrylate resin, polyurethane acrylate resin, methacrylic resin, cyanoacrylate resin, silicone resin, oxyvinylethylene resin, vinyl ether resin, etc. Among them, from the viewpoint of transparency and weather resistance, at least one selected from the group consisting of silicone resin, epoxy acrylate resin, urethane acrylate resin, and methacrylic resin is preferable. The material constituting the core layer 14 may be one type or two or more types.

[0026] 3(A) and 3(B), the cross-sectional shape of the core layer 14 perpendicular to the light guide path 15 is preferably substantially semicircular. If the core layer 14 has a shape without corners on the upper surface as in this example, the light guided through the light guide path 15 to the light diffusion layer 18 is less likely to leak outside on the way, and the desired design can be illuminated more efficiently.

[0027] The thickness h1 of the core layer 14 (FIG. 3(A)) is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. If the thickness h1 of the core layer 14 is equal to or more than the lower limit, the light transmittance is improved, and the brightness and uniformity are enhanced. The thickness h1 of the core layer 14 is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. If the thickness h1 of the core layer 14 is equal to or less than the upper limit, the degree of freedom in design is improved. The preferable lower limit and upper limit of the thickness h1 of the core layer 14 can be arbitrarily combined, and for example, a range of 5 μm to 100 μm is preferable. In the present invention, the thickness of the core layer is the average value of thicknesses measured at any ten points on the core layer, and the same applies to the thicknesses of the other layers. When the cross-sectional shape is substantially semicircular as shown in FIGS. 3(A) and 3(B), the thickness h1 of the core layer means the maximum thickness in a cross section perpendicular to the light guide path 15.

[0028] The total light transmittance of the core layer 14 is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more. When the total light transmittance of the core layer 14 is equal to or more than the lower limit, the target design can be illuminated more efficiently. The total light transmittance of the core layer is a value measured in accordance with JIS K7375:2008.

[0029] As shown in the example of FIG. 3(A), when the cross-sectional shape of the core layer 14 perpendicular to the light guide 15 is substantially semicircular, the angle θ of the contact portion between the side surface of the core layer 14 and the front surface of the first cladding layer 16A is preferably 30 degrees or more, more preferably 60 degrees or more, and even more preferably 80 degrees or more. If the angle θ is equal to or more than the lower limit, the light passing through the light guide 15 is less likely to leak to the outside, and the desired design can be illuminated more efficiently. The angle θ is preferably 120 degrees or less, more preferably 110 degrees or less, and even more preferably 100 degrees or less. If the angle θ is equal to or less than the upper limit, the uniformity of the light is improved. The preferable lower limit and upper limit of the angle θ can be arbitrarily combined, and for example, a range of 30 degrees or more and 30 degrees or less is preferable.

[0030] Similarly, in the case where the core layer 14 is provided directly on the front surface of the base sheet 10, as in the example shown in Figure 3 (B), the angle θ of the contact portion between the side of the core layer 14 and the front surface of the base sheet 10 is preferably 30 degrees or more, more preferably 60 degrees or more, even more preferably 80 degrees or more, and is preferably 120 degrees or less, more preferably 110 degrees or less, and even more preferably 100 degrees or less. Note that angle θ is the angle between a tangent k to the side of core layer 14 at the contact point between the side of core layer 14 and the front surface of base sheet 10 or first clad layer 16A in a cross section perpendicular to light guide path 15 of core layer 14, and the front surface of base sheet 10 or first clad layer 16A.

[0031] In order to suppress leakage of light from the core layer 14, it is preferable that the shape of the core layer 14 viewed from the Z direction has no corners in the light guide path 15 formed by the core layer 14 or in the portion covering the light diffusion layer 18 of the core layer 14. For example, as shown in the example in FIG. 2, when the light diffusion layer 18 has a rectangular shape in plan view, the portion of the core layer 14 covering the light diffusion layer 18 preferably has a rectangular shape with rounded corners.

[0032] 2, when the light guide 15 formed by the core layer 14 has a portion 17 curved in an arc shape, the radius of curvature R of the curved portion 17 as viewed from the Z direction is preferably 100 μm or more, more preferably 110 μm or more, and even more preferably 120 μm or more. If the radius of curvature R of the curved portion 17 of the light guide 15 is equal to or more than the lower limit, light is less likely to leak to the outside at the curved portion 17 of the light guide 15, and the intended design can be illuminated more efficiently. There is no particular upper limit for the radius of curvature R of the curved portion 17 of the light guide 15. The radius of curvature R means the radius of curvature of a curve passing through the center of the curved portion 17 in the light guide 15 when viewed from the Z direction.

[0033] The constituent material of the cladding layer 16 is preferably a UV-curable material, but is not limited thereto. Examples of the UV-cured material constituting the cladding layer 16 include acrylic resin, methacrylic resin, epoxy acrylate resin, polyurethane acrylate resin, silicone acrylate resin, urethane acrylate resin, cyanoacrylate resin, vinyl ether resin, and oxyvinyl ethylene resin. Among them, from the viewpoints of optical properties, mechanical strength, and processability, at least one selected from the group consisting of acrylic resin, epoxy acrylate resin, oxyvinyl ethylene resin, urethane acrylate resin, and methacrylic resin is preferable. The material constituting the cladding layer 16 may be one type or two or more types.

[0034] The thickness of the cladding layer 16 is preferably 1 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. If the thickness of the cladding layer 16 is equal to or more than the lower limit, the light passing through the light guide 15 is less likely to leak to the outside, and the desired design can be illuminated more efficiently. The thickness of the cladding layer 16 is preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less. If the thickness of the cladding layer 16 is equal to or less than the upper limit, the light propagation characteristics are improved. The preferable lower limit and upper limit of the thickness of the cladding layer 16 can be arbitrarily combined, and for example, a range of 1 μm to 30 μm is preferable. When the cladding layer 16 is made up of a first cladding layer 16A and a second cladding layer 16B, the thickness of the cladding layer 16 means the total thickness of the first cladding layer 16A and the second cladding layer 16B.

[0035] The total light transmittance of the cladding layer 16 is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more. If the total light transmittance of the cladding layer 16 is equal to or more than the lower limit, the intended design can be illuminated more efficiently. The total light transmittance of the cladding layer is a value measured in accordance with JIS K7375:2008.

[0036] The ratio (d1 / h1) of the distance d1 (FIGS. 2 and 5) between the end of the cladding layer 16 and the end of the core layer 14 closest to the end of the cladding layer 16 as viewed in the thickness direction to the thickness h1 (FIG. 3(A)) of the core layer 14 is preferably 1 or more, more preferably 5 or more, and even more preferably 10 or more. If d1 / h1 is equal to or more than the lower limit, the light guided to the light diffusion layer 18 through the light guide path 15 is less likely to leak to the outside on the way, and the intended design can be illuminated more efficiently. d1 / h1 is preferably 100 or less, more preferably 50 or less, and even more preferably 30 or less. If d1 / h1 is equal to or less than the upper limit, the light propagation characteristics are improved. The preferable lower limit and upper limit of d1 / h1 can be arbitrarily combined, and for example, a range of 1 to 100 is preferable.

[0037] The light diffusion layer 18 is a layer that diffuses the light emitted from the light source 20 and passing through the light guide path 15. The light diffusion layer 18 can increase the luminance of the light-transmitting portion 26 on the operation surface 1a. The shape and number of the light diffusing layer 18 are not particularly limited, and can be appropriately set according to the shape and number of the light transmitting portions 26 formed on the cover plate 24 .

[0038] The light diffusion layer 18 may be any layer capable of diffusing the light that has passed through the light guide path 15, and examples thereof include a transparent layer having fine irregularities on at least one surface that diffuse the light, and a transparent layer containing light diffusing particles. Examples of the constituent material of the transparent layer include polycarbonate, acrylic resin, ABS resin, polystyrene, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, etc. As the constituent material of the transparent layer, one type may be used alone, or two or more types may be used in combination.

[0039] Examples of the light-diffusing particles include titanium oxide, silica, hollow silica, barium titanate, barium sulfate, silicone powder, resin beads (acrylic resin beads, styrene resin beads, etc.), etc. As the light-diffusing particles, one type may be used alone, or two or more types may be used in combination.

[0040] The thickness of the light diffusion layer 18 is preferably 0.1 μm or more, and more preferably 1 μm or more. If the thickness of the light diffusion layer 18 is equal to or more than the lower limit, the light diffusion effect is easily exerted. The thickness of the light diffusion layer 18 is preferably 50 μm or less, and more preferably 20 μm or less. If the thickness of the light diffusion layer 18 is equal to or less than the upper limit, the sensor sheet can be easily made thin.

[0041] (light source) Light source 20 may be any light emitting body capable of emitting light from the side surface of the end of light guide 15, and examples thereof include light emitting diodes (LEDs) and cold cathode fluorescent lamps, with LEDs being preferred. As an example shown in FIGS. 1 and 2, the light source 20 is preferably fixed to the front surface 10a of the base sheet 10 by a potting portion 30. As shown in FIG.

[0042] The material of the potting portion 30 for fixing the light source 20 is preferably the same as that of the core layer 14, but is not limited thereto. It is preferable that at least the light emitting portion of the light source 20 is covered with the same material as the core layer 14. This makes it possible to suppress leakage of light incident from the light source 20 to the light guide path 15, and to more efficiently illuminate the intended design.

[0043] (Cover plate) The cover plate 24 includes a transparent layer 32 and a light-shielding layer 34 provided on the rear side of the transparent layer 32 . In the cover plate 24, a portion on the back side of the transparent layer 32 where the light-shielding layer 34 is not provided becomes a transparent light-transmitting portion 26 that transmits light in the Z direction (thickness direction), and a portion on the back side of the transparent layer 32 where the light-shielding layer 34 is provided becomes an opaque light-shielding portion 28 that blocks part or all of the light. The light-transmitting portion 26 and the light-shielding portion 28 are formed so that any pattern or character is formed on the operation surface 1a. At least a portion of the light diffused by the light diffusion layer 18 and emitted toward the cover plate 24 passes through the light transmitting portion 26 and is emitted to the outside.

[0044] In this specification, "transparent" means that the total light transmittance measured in accordance with JIS K7375:2008 is 50% or more, and "opaque" means that the total light transmittance is less than 50%.

[0045] Examples of the constituent material of the transparent layer 32 include polycarbonate, acrylic resin, ABS resin, polystyrene, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, etc. As the constituent material of the transparent layer 32, one type may be used alone, or two or more types may be used in combination.

[0046] The arrangement pattern of the light-shielding layer 34, that is, the arrangement pattern of the light-transmitting portions 26 and the light-shielding portions 28, is appropriately set according to the designs and characters to be displayed on the operation surface 1a. The light-shielding layer 34 may be a printed layer, a colored resin layer, or a punched resin layer. The "printed layer" constituting the light-shielding layer 34 may include not only a coating film containing a pigment or a coloring matter, but also a discontinuous vapor deposition film.

[0047] The thickness of the cover plate 24 is not particularly limited, and can be, for example, 50 μm or more and 500 μm or less.

[0048] (Adhesive layer) 1 and 2, the cover plate 24 is adhered to the clad layer 16 via an adhesive layer 22. When the clad layer 16 is provided along the light guide path 15 as in the example shown in Fig. 5, the cover plate 24 is adhered to the clad layer 16 and the base sheet 10 via the adhesive layer 22.

[0049] As the adhesive layer 22, an adhesive layer using a known curing adhesive (a liquid adhesive before adhesion) or a pressure-sensitive adhesive (a gel-like pressure-sensitive adhesive before adhesion) is applied. The adhesive layer may also be a substrate-type adhesive layer in which an adhesive or a pressure-sensitive adhesive is disposed on both sides of a substrate layer. An example of a substrate-type adhesive layer is a known double-sided tape. Examples of the adhesive and pressure-sensitive adhesive include acrylic resin, urethane resin, ethylene-vinyl acetate copolymer, etc. The curable adhesive may be a solvent type that contains a solvent that volatilizes upon curing, or may be a hot melt type.

[0050] The adhesive layer 22 is preferably transparent. The light transmittance of the adhesive layer is mainly affected by the type of adhesive that constitutes the adhesive layer and the thickness of the adhesive layer. The thickness of the adhesive layer 22 can be, for example, 1 μm or more and 75 μm or less. The thickness of the adhesive layer 22 using the curable adhesive is preferably 1 μm or more and 20 μm or less. The thickness of the adhesive layer 22 using the pressure-sensitive adhesive is preferably 10 μm or more and 75 μm or less.

[0051] 4 and 6, the adhesive layer 22 is preferably provided so as not to overlap the core layer 14 when viewed in the Z direction (thickness direction). This can further suppress leakage of light from areas other than the intended illumination area.

[0052] The ratio (d2 / h2) of the shortest distance d2 between the adhesive layer 22 and the core layer 14 when viewed from the Z direction (thickness direction) to the thickness h2 of the adhesive layer 22 is preferably 10 or more, more preferably 20 or more, and even more preferably 40 or more. If d2 / h2 is equal to or more than the lower limit, it becomes easier to suppress light leakage from areas other than the intended illumination area, and the intended design can be illuminated more efficiently. d2 / h2 is preferably equal to or less than 100, more preferably equal to or less than 80, even more preferably equal to or less than 60, and particularly preferably equal to or less than 50. If d2 / h2 is equal to or less than the upper limit, resistance to bending and flexing is improved. The preferable lower limit and upper limit of d2 / h2 can be arbitrarily combined, and for example, a range of 10 to 50 is preferable.

[0053] (electrode layer) The electrode layer 12 can be at least one of an XY electrode body that enables input in the planar XY directions, which are the surface directions of the operating surface 1a of the sensor sheet 1, to be detected by changes in capacitance, and a Z electrode body that enables input in the Z direction (thickness direction) to be detected by changes in capacitance. As the electrode layer 12, only an XY electrode body may be provided, only a Z electrode body may be provided, or both an XY electrode body and a Z electrode body may be provided.

[0054] The XY electrode body may be any electrode body capable of detecting contact or proximity of a conductor by a change in capacitance, and may be of a self-capacitance type or a mutual capacitance type. The form of the self-capacitance type XY electrode body is not particularly limited, and examples thereof include solid electrodes such as circular, elliptical, and rectangular electrodes, and diamond patterns. The form of the mutual capacitance type XY electrode body is not particularly limited, and examples thereof include solid electrodes such as circular, elliptical, and rectangular electrodes, and comb-tooth electrodes.

[0055] The electrode layer 12, which is the XY electrode body, can be formed, for example, by printing a conductive paste on the back surface 10b of the base sheet 10. In this specification, "conductive" means that the electrical resistance is less than 1 MΩ. Examples of conductive substances contained in the conductive paste include conductive polymers (polythiophene conductive polymers (PEDOT / PSS), indium-doped tin oxide (ITO), etc.), conductive nanowires (silver nanowires, gold nanowires, carbon nanotubes, etc.), metal particles (silver particles, copper particles, gold particles, etc.), conductive metal oxide particles (ITO particles, etc.), carbon (carbon black, graphite, etc.), etc. The conductive paste may contain one type of conductive substance or two or more types of conductive substances.

[0056] 7, an example of the Z electrode body is a laminate 12A in which an elastic layer 45 is disposed between a first electrode 41 and a second electrode 42 in a state where it is sandwiched between a first film 43 and a second film 44. For example, this laminate 12A can be provided on the back surface 10b of the base sheet 10 via an adhesive layer such as double-sided tape. When a Z electrode body is provided as the electrode layer 12, when the elastic layer 45 is compressed and deformed by pressing the operation surface 1a, the distance between the first electrode 41 and the second electrode 42 becomes closer and the capacitance changes, so that the press can be detected.

[0057] The first electrode 41 and the second electrode 42 can be pressure-sensitive electrodes of a known type, and may be of a self-capacitance type or a mutual capacitance type. Examples of materials constituting the first electrode 41 and the second electrode 42 include the same conductive materials as those exemplified for the XY electrode body.

[0058] The elastic layer 45 in the example shown in Fig. 7 includes a pair of first and second sheet portions 45a and 45b, and a plurality of column portions 45c sandwiched between the first and second sheet portions 45a and 45b. The elastic layer 45 is a rubber-like elastic body including the pair of first and second sheet portions 45a and 45b, and the plurality of column portions 45c. Note that the elastic layer 45 is not limited to the form shown in Fig. 7.

[0059] The elastic material constituting the elastic layer 45 is preferably one that has an appropriate degree of compressive deformation in the thickness direction when pressed and provides a good feeling of pressure. Examples of the elastic material include thermosetting elastomers such as urethane rubber, isoprene rubber, ethylene propylene rubber, natural rubber, ethylene propylene diene rubber, styrene butadiene rubber, and silicone rubber; thermoplastic elastomers such as urethane-based, ester-based, styrene-based, olefin-based, butadiene-based, and fluorine-based elastomers; and composites thereof. These materials may be used alone or in combination of two or more.

[0060] The Shore A hardness of the elastic layer 45 measured with a thickness of 1 cm is preferably 85 or less. If the Shore A hardness is 85 or less, the elastic layer can be easily elastically deformed when pressed. However, if the elastic layer is too soft, recovery after elastic deformation becomes slow, so the Shore A hardness of the elastic layer 45 is preferably 10 or more.

[0061] As a material for forming the first film 43 and the second film 44, an insulating resin material can be used, such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyvinyl chloride, polymethyl methacrylate, and urethane. These may be used alone or in combination of two or more.

[0062] [Sensor sheet manufacturing method] The sensor sheet can be manufactured by any known method for manufacturing a sensor sheet. However, it is preferable that the core layer, cladding layer and light diffusion layer are laminated by mesh screen printing or metal plate printing. More specifically, the manufacturing method for the sensor sheet of the present invention preferably includes stacking a first clad layer 16A, a light diffusion layer 18, a core layer 14, and a second clad layer 16B in this order on the front surface 10a of the base sheet 10 by mesh screen printing or metal plate printing to form a clad layer 16 in which the core layer 14 is sandwiched between the first clad layer 16A and the second clad layer 16B.

[0063] When mesh screen printing is used, it is preferable that the screen mesh count is between 80 mesh and 325 mesh and the material of the screen mesh is polyester, which allows for the formation of a highly accurate and uniform coating film.

[0064] From the viewpoint of high accuracy and high resolution, the screen mesh count is preferably 80 mesh or more, more preferably 200 mesh or more, and even more preferably 325 mesh or more. From the viewpoint of coating thickness, the screen mesh count is preferably 325 mesh or less, more preferably 250 mesh or less, and even more preferably 200 mesh or less.

[0065] Examples of polyesters constituting the screen mesh include Tetoron and Dacron. These may be used alone or in combination of two or more. Among them, Tetoron is preferred from the viewpoints of high tension, suppression of tension change over time, and printing dimensional stability.

[0066] When metal plate printing is used, the thickness of the metal plate is preferably 50 μm or more and 300 μm or less, which makes it possible to obtain an appropriate and optimal coating film. From the viewpoint of thick coating, the thickness of the metal plate is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 150 μm or more. From the viewpoint of high accuracy and high resolution, the thickness of the metal plate is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 200 μm or less.

[0067] The cover plate 24 can be manufactured by forming the light-shielding layer 34 by printing paint on the back surface of the transparent sheet that constitutes the transparent layer 32 using a known printing method. The cover plate 24 can be attached to the base sheet 10 on which the light diffusing layer 18, the core layer 14 and the cladding layer 16 are formed, for example, by using a double-sided tape.

[0068] The electrodes of the XY electrode body and the first electrode 41 and second electrode 42 of the Z electrode body can be formed, for example, by printing a conductive paste. The elastic layer 45 can be manufactured, for example, by the following method. The second sheet portion 45b is formed on one side of the second film 44 by screen printing or the like, and the column portion 45c is pressed against the surface while irradiating it with ultraviolet light to bond them. Next, the first film 43 is overlaid with the first sheet portion 45a formed on one side of the first film 43 by screen printing or the like, and the two are pressed together while irradiating it with ultraviolet light. This results in the elastic layer 45 sandwiched between the first film 43 and the second film 44.

[0069] In the sensor sheet of the present invention described above, the core layer forms a light guide path that guides light from the light source to the light diffusion layer, and the core layer is covered with a clad layer, so that the intended design can be efficiently illuminated while suppressing light leakage from areas other than the intended illumination area. In addition, the light source and the illumination area can be arranged arbitrarily. Furthermore, the sensor sheet of the present invention has a high degree of freedom in design, can be easily manufactured, and can easily be made thin, because the light diffusion layer, the core layer, and the clad layer can be laminated by a printing method such as mesh screen printing or metal plate printing.

[0070] The sensor sheet and the manufacturing method thereof according to the present invention are not limited to the above-mentioned embodiment. Within the scope of the present invention, the components in the above-described embodiment may be replaced with well-known components as appropriate, and the above-described modified examples may be combined as appropriate. [Explanation of symbols]

[0071] 1...sensor sheet, 10...base material sheet, 10a...front surface, 10b...rear surface, 12...electrode layer, 14...core layer, 15...light guide path, 16...clad layer, 18...light diffusion layer, 20...light source, 22...adhesive layer, 24...cover plate, 26...light-transmitting portion, 28...light-shielding portion, 30...potting portion, 32...transparent layer, 34...light-shielding layer.

Claims

1. A base sheet; an electrode layer provided on the back surface of the base sheet; a core layer and a clad layer provided on the front surface of the base sheet; a light diffusing layer provided within the core layer; A light source; A cover plate; the core layer forms a light guide path that guides light from the light source to the light diffusion layer, the clad layer is provided to cover the periphery of the core layer, The light source is disposed on a side surface of an end portion of the light guide path, the cover plate is provided on the clad layer on the opposite side to the base sheet via an adhesive layer; The cover plate is formed with a light-shielding portion and a light-transmitting portion, The light diffusion layer is provided at a position overlapping the light transmitting portion when viewed in the thickness direction of the sensor sheet.

2. the core layer is made of a UV-cured product of at least one material selected from the group consisting of an acrylic resin, a silicone acrylate resin, a urethane acrylate resin, an epoxy acrylate resin, a polyurethane acrylate resin, a methacrylic resin, and a cyanoacrylate resin; The thickness of the core layer is 5 μm or more and 100 μm or less, The sensor sheet according to claim 1 , wherein the core layer has a total light transmittance of 90% or more.

3. 2. The sensor sheet according to claim 1, wherein the cross-sectional shape of the core layer perpendicular to the light guide path is approximately semicircular, and the angle of the contact portion between the side of the core layer and the front surface of the base sheet or the cladding layer on which the core layer is formed is 30 degrees or more.

4. The sensor sheet according to claim 1 , wherein the light guide path has a portion curved in an arc shape, and the curved portion has a radius of curvature R of 100 μm or more.

5. the cladding layer is made of a UV-cured product of at least one material selected from the group consisting of an acrylic resin, a methacrylic resin, an epoxy acrylate resin, a polyurethane acrylate resin, a silicone acrylate resin, a urethane acrylate resin, a cyanoacrylate resin, and a vinyl ether resin; The thickness of the cladding layer is 1 μm or more and 30 μm or less, The sensor sheet according to claim 1 , wherein the cladding layer has a total light transmittance of 90% or more.

6. The sensor sheet according to claim 1 , wherein a ratio of a distance between an end of the cladding layer and an end of the core layer closest to the end of the cladding layer to a thickness of the core layer is 1 or more and 100 or less when viewed in the thickness direction.

7. The adhesive layer is provided so as not to overlap the core layer when viewed in a thickness direction, The sensor sheet according to claim 1 , wherein a ratio of a shortest distance between the adhesive layer and the core layer as viewed in a thickness direction to a thickness of the adhesive layer is 10 or more.

8. The sensor sheet according to claim 1 , wherein the reflectance of the base sheet is 90% or more.

9. The sensor sheet according to claim 1 , wherein a light emitting portion of the light source is covered with the same material as the core layer.

10. A method for manufacturing the sensor sheet according to claim 1, A method for manufacturing a sensor sheet, comprising: laminating a first clad layer, the light diffusion layer, the core layer, and a second clad layer in that order on the front surface of the base sheet by mesh screen printing, in which the screen mesh count is 80 mesh or more and 325 mesh or less and the screen mesh is made of polyester, or by metal plate printing, in which the thickness of the metal plate is 50 μm or more and 300 μm or less, to form the clad layer in which the core layer is sandwiched between the first clad layer and the second clad layer.

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