Method for manufacturing pressure sensor sheet, pressure sensor sheet, and pressure sensor

Abstract

[Problem] To provide: a method for manufacturing a pressure sensor sheet with which it is possible to suppress the occurrence of variations in detection sensitivity caused by penetration of adhesive into a foam layer; a pressure sensor sheet manufactured by the manufacturing method; and a pressure sensor employing the pressure sensor sheet. [Solution] This method for manufacturing a pressure sensor sheet includes a first adhesive layer lamination step, a layer-to-be-bonded lamination step, and a curing step. In the first adhesive layer lamination step, a first adhesive layer 14a, which is a first adhesive in a semi-cured state, is laminated onto a foam layer 13. In the layer-to-be-bonded lamination step, a layer-to-be-bonded is laminated onto the first adhesive layer 14a via a second adhesive layer 14b, which is a second adhesive. In the curing step, the first adhesive layer 14a and the second adhesive layer 14b are cured.

Description

Method for manufacturing a sheet for a pressure sensor, sheet for a pressure sensor, and pressure sensor

[0001] The present invention relates to a method for manufacturing a sheet for a pressure sensor, a sheet for a pressure sensor, and a pressure sensor.

[0002] Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2022-092662) discloses a pressure sensor including a first electrode sheet having a first electrode layer formed on a first insulating sheet, a second electrode sheet having a second electrode layer formed on a second insulating sheet, a foam sheet, an elastic body layer sandwiched between the first electrode sheet and the second electrode sheet, and adhesive layers formed on the surfaces of the elastic body layer on the side of the first electrode sheet and the side of the second electrode sheet, respectively.

[0003] The pressure sensor disclosed in Patent Document 1 is used, for example, as a capacitive pressure sensor by being placed on a glass plate covering the display surface of a display device. Its detection principle is as follows. That is, when pressure is applied as a pressing force perpendicular to the first electrode sheet on the front surface, the elastic body layer is deformed in the vertical direction, and the first electrode layer of the first electrode sheet approaches the second electrode layer of the second electrode sheet, and the electrode distance decreases. Since the capacitance is inversely proportional to the electrode distance, the capacitance increases. By measuring and converting the increase amount of this capacitance, the pressure in the thickness direction of the pressure sensor can be detected.

[0004] Japanese Unexamined Patent Application Publication No. 2022-092662

[0005] In the pressure sensor of Patent Document 1, adhesive layers are formed on the surfaces of the elastic body layer on the side of the first electrode sheet and the side of the second electrode sheet. A part of the adhesive constituting the adhesive layer may penetrate (soak into) the inside of the bubbles of the elastic body layer when applied to the surface of the elastic body layer. The adhesive that has penetrated into the bubbles may inhibit the uniform deformation of the elastic body layer and cause variations in the detection sensitivity of the pressure sensor by curing.

[0006] An object of the present invention is to provide a method for manufacturing a sheet for a pressure sensor in which the penetration of an adhesive into a foam layer is suppressed, a sheet for a pressure sensor manufactured by the manufacturing method, and a pressure sensor using the sheet for a pressure sensor.

[0007] Several embodiments for solving the problem are described below. These embodiments can be combined as needed.

[0008] A method for manufacturing a pressure sensor sheet according to a first aspect of the present invention comprises a first adhesive layer lamination step, a layer to be bonded lamination step, and a curing step. In the first adhesive layer lamination step, a first adhesive layer, which is a first adhesive in a semi-cured state, is laminated onto a foam layer. In the layer to be bonded lamination step, a layer to be bonded is laminated onto the first adhesive layer via a second adhesive layer, which is a second adhesive. In the curing step, the first adhesive layer and the second adhesive layer are cured.

[0009] A method for manufacturing a pressure sensor sheet according to a second aspect of the present invention is a method for manufacturing a pressure sensor sheet according to a first aspect, wherein the first adhesive layer lamination step includes a step of applying a first adhesive to a foam layer and a step of partially curing the first adhesive to form a first adhesive layer laminated on the foam layer.

[0010] A method for manufacturing a pressure sensor sheet according to a third aspect of the present invention is a method for manufacturing a pressure sensor sheet according to a first aspect, wherein the first adhesive layer lamination step includes the steps of applying a first adhesive to a release film, forming a first adhesive layer by bringing the first adhesive to a semi-cured state, attaching a foam layer to the first adhesive layer, and peeling the release film from the first adhesive layer.

[0011] A method for manufacturing a pressure sensor sheet according to a fourth aspect of the present invention is a method for manufacturing a pressure sensor sheet according to a second or third aspect, wherein the adhesive layer lamination step includes a step of applying a second adhesive to a first adhesive layer to form a second adhesive layer, and a step of attaching the adhesive layer to the second adhesive layer.

[0012] A method for manufacturing a pressure sensor sheet according to a fifth aspect of the present invention is a method for manufacturing a pressure sensor sheet according to a second or third aspect, wherein the adhesive layer lamination step includes a step of applying a second adhesive to an adhesive layer to form a second adhesive layer, and a step of attaching the second adhesive layer to a first adhesive layer.

[0013] A method for manufacturing a pressure sensor sheet according to a sixth aspect of the present invention is a method for manufacturing a pressure sensor sheet according to a first aspect, wherein the first adhesive layer lamination step includes a step of laminating an adhesive film formed of a first adhesive in a semi-cured state onto a foam layer.

[0014] A method for manufacturing a pressure sensor sheet according to the seventh aspect of the present invention is a method for manufacturing a pressure sensor sheet according to any of the first or sixth aspects, wherein the layer to be bonded is an electrode layer.

[0015] A pressure sensor sheet according to the eighth aspect of the present invention comprises a foam layer, a first adhesive layer laminated on the foam layer, a second adhesive layer laminated on the first adhesive layer, and a layer to be bonded to the foam layer via the first and second adhesive layers.

[0016] A pressure sensor sheet according to the ninth aspect of the present invention is a pressure sensor sheet according to the eighth aspect, further comprising a third adhesive layer laminated on the side opposite to the side on which the first adhesive layer of the foam layer is laminated, and a fourth adhesive layer laminated on the third adhesive layer.

[0017] A pressure sensor sheet according to the tenth aspect of the present invention is a pressure sensor sheet according to the eighth or ninth aspect, wherein the adhesive layer is an electrode layer.

[0018] A pressure sensor sheet according to the eleventh aspect of the present invention is a pressure sensor sheet according to the ninth or tenth aspect, wherein the first adhesive layer and the third adhesive layer are made of the same adhesive, and the second adhesive layer and the fourth adhesive layer are made of the same adhesive.

[0019] A pressure sensor sheet according to the twelfth aspect of the present invention is a pressure sensor sheet according to any of the eighth or eleventh aspects, wherein the foam layer may include an adhesive-penetrating layer into which an adhesive, which is the first adhesive layer, has permeated. The thickness of the adhesive-penetrating layer relative to the thickness of the foam layer is 0 percent or more and 30 percent or less.

[0020] A pressure sensor according to the thirteenth aspect of the present invention comprises a pressure sensor sheet according to any of the eighth or twelfth aspects.

[0021] According to this method for manufacturing pressure sensor sheets, the penetration of adhesive into the foam layer is suppressed. As a result, variations in the detection sensitivity of the manufactured pressure sensor sheets and the pressure sensors using them are suppressed.

[0022] This is a schematic diagram of a pressure sensor. This is a diagram showing the process of manufacturing a sheet for a pressure sensor. This is a cross-sectional view showing the manufacturing method of a sheet for a pressure sensor. This is a cross-sectional view showing the manufacturing method of a sheet for a pressure sensor. This is a cross-sectional view showing the first step according to Modification 1. This is a cross-sectional view showing the first step according to Modification 1. This is a cross-sectional view showing the second step according to Modification 2. This is a cross-sectional view of a sheet for a pressure sensor according to Modification 6.

[0023] <Embodiment> (1) Overall configuration diagram 1 of the pressure sensor 100 is a schematic diagram of the pressure sensor 100, including a cross-sectional view of the pressure sensor sheet 10 according to an embodiment of the present invention. The pressure sensor 100 is a capacitive pressure sensor. The pressure sensor 100 mainly comprises a pressure sensor sheet 10 and a detection circuit 20. As will be described in detail later, in the pressure sensor 100, the detection circuit 20 detects at multiple points the pressure (stress in the thickness direction) acting on the pressure sensor sheet 10 due to a load P applied to the surface of the pressure sensor sheet 10 (the surface on the side of the first electrode sheet 11, which will be described later). Here, multi-point detection means that pressure detection is performed at multiple positions on the pressure sensor sheet 10.

[0024] (2) Detailed configuration of the pressure sensor 100 (2-1) Sheet for pressure sensor 10 The sheet for pressure sensor 10 includes a first electrode sheet 11, a second electrode sheet 12, a foam layer 13, and an adhesive layer 14.

[0025] (2-1-1) First electrode sheet 11 The first electrode sheet 11 is laminated on the first surface S1, which is one of the main surfaces of the foam layer 13, via a first adhesive layer 14a and a second adhesive layer 14b (described later). The first electrode sheet 11 has a first insulating sheet 11a and a first electrode layer 11b formed on the surface of the first insulating sheet 11a facing the foam layer 13.

[0026] The first insulating sheet 11a is a layer that supports the first electrode layer 11b. The material of the first insulating sheet 11a is not particularly limited, but examples include polyethylene terephthalate resin (PET), urethane resin, and silicone resin.

[0027] The first electrode layer 11b includes a plurality of first electrode patterns and a plurality of row wirings (not shown). The plurality of first electrode patterns are formed in a matrix on the surface of the first insulating sheet 11a facing the foam layer 13. The row wirings electrically connect adjacent first electrode patterns in a predetermined first direction. The first electrode layer 11b is an example of a layer to be bonded.

[0028] The material of the first electrode layer 11b is not particularly limited, but examples include metals such as gold, silver, copper, platinum, palladium, aluminum, and rhodium; conductive pastes in which metal particles are dispersed in a resin binder; and organic semiconductors such as polyhexylthiophene, polydioctylfluorene, pentacene, and tetrabenzoporphyrin.

[0029] When a metal is used as the material, the first electrode layer 11b is formed by a method in which a conductive film is formed over the entire surface using a plating method, sputtering method, vacuum deposition method, ion plating method, etc., and then patterned by etching. When a conductive paste or organic semiconductor is used as the material, the first electrode layer 11b is formed by a method in which a pattern is directly formed using a printing method such as screen printing, gravure printing, or offset printing.

[0030] The first electrode layer 11b may consist of only one layer or of two or more layers. The thickness of the first electrode layer 11b is appropriately selected within the range of 30 μm to 100 μm.

[0031] (2-1-2) Second electrode sheet The second electrode sheet 12 is laminated on the second surface S2 of the foam layer 13, which is the surface opposite to the first surface S1, via a third adhesive layer 14c and a fourth adhesive layer 14d (described later). The second electrode sheet 12 has a second insulating sheet 12a and a second electrode layer 12b formed on the surface of the second insulating sheet 12a facing the foam layer 13.

[0032] The second insulating sheet 12a is a layer that supports the second electrode layer 12b. The material of the second insulating sheet 12a is not particularly limited, but examples include polyethylene terephthalate resin (PET), urethane resin, and silicone resin.

[0033] The second electrode layer 12b includes a plurality of second electrode patterns and a plurality of column wirings (not shown). The plurality of second electrode patterns are formed in a matrix on the surface of the second insulating sheet 12a facing the foam layer 13, such that each overlaps with at least a portion of the first electrode pattern 11c in a plan view of the pressure sensor sheet 10. The column wirings electrically connect adjacent second electrode patterns in a direction intersecting the first direction (typically orthogonal directions). The second electrode layer 12b is an example of a bonded layer.

[0034] The material of the second electrode layer 12b is not particularly limited, but examples include metals such as gold, silver, copper, platinum, palladium, aluminum, and rhodium; conductive pastes in which metal particles are dispersed in a resin binder; and organic semiconductors such as polyhexylthiophene, polydioctylfluorene, pentacene, and tetrabenzoporphyrin.

[0035] When a metal is used as the material, the second electrode layer 12b is formed by a method in which a conductive film is formed over the entire surface using a plating method, sputtering method, vacuum deposition method, ion plating method, etc., and then patterned by etching. When a conductive paste or organic semiconductor is used as the material, the first electrode layer 11b is formed by a method in which a pattern is directly formed using a printing method such as screen printing, gravure printing, or offset printing.

[0036] The second electrode layer 12b may consist of only one layer or of two or more layers. The thickness of the second electrode layer 12b is appropriately selected within the range of 30 μm to 100 μm.

[0037] (2-1-3) Foam layer 13 The foam layer 13 is an elastic layer that deforms under load P applied to the surface of the pressure sensor sheet 10. The foam layer 13 has adhesive layers 14 arranged on both sides. The foam layer 13 is an elastic foam in which air bubbles 13a are dispersed inside. The average diameter of the air bubbles 13a is appropriately selected, for example, within the range of 2 to 1000 μm, although this is not limited to the foam layer 13a.

[0038] The average diameter of bubble 13a can be determined from cross-sectional images obtained through cross-sectional observation using image processing methods. Cross-sectional observation typically involves cutting the sample to create an opening and observing it with an optical microscope or scanning electron microscope. Commercially available image processing software can be used. Alternatively, the bubble diameter can be measured and calculated manually from the cross-sectional photograph. If the cross-section is elliptical, the square root of the product of the major and minor axes can be used as the bubble diameter.

[0039] The material of the foam layer 13 is not particularly limited, but examples include polyethylene resin, silicone resin, urethane resin, and various other rubbers such as natural rubber and synthetic rubber. Silicone resin is particularly preferred because it improves the resilience of the foam layer 13 after the pressure is released. Furthermore, silicone resin is preferred because it is less prone to uneven deformation of the foam layer 13 due to temperature changes, and it is possible to maintain a constant sensitivity of the pressure sensor 100.

[0040] The foam layer 13 is not particularly limited, but for example, it can be manufactured by dispersing a thermally decomposing foaming agent such as azodicarbonamide or bicarbonate, or a thermally expandable microcapsule foaming agent in which fluorocarbons or hydrocarbons are encapsulated in thermoplastic resin capsules, in the aforementioned resin, and using a molding method such as bead foaming, batch foaming, press foaming, atmospheric pressure secondary foaming, injection foaming, or extrusion foaming, which involves applying heat.

[0041] The thickness of the foam layer 13 is appropriately selected from the range of 50 μm to 500 μm, preferably from 50 μm to 200 μm.

[0042] (2-1-4) Adhesive layer 14 The adhesive layer 14 includes a first adhesive layer 14a, a second adhesive layer 14b, a third adhesive layer 14c, and a fourth adhesive layer 14d.

[0043] The first adhesive layer 14a and the second adhesive layer 14b connect (adhere) the first electrode sheet 11 to the foam layer 13. More specifically, the first adhesive layer 14a is laminated on the first surface S1 of the foam layer 13. The second adhesive layer 14b is laminated on the first adhesive layer 14a.

[0044] The third adhesive layer 14c and the fourth adhesive layer 14d connect (adhere) the second electrode sheet 12 to the foam layer 13. More specifically, the third adhesive layer 14c is laminated on the second surface S2 of the foam layer 13. The fourth adhesive layer 14d is laminated on the third adhesive layer 14c.

[0045] The adhesive layer 14 is not particularly limited, and for example, it is a thermosetting adhesive, a UV curable adhesive, or a moisture curable adhesive. When the first electrode layer 11b, the second electrode layer 12b, the first wiring 21, the second wiring 22 (described later), etc. have opaque portions, uneven curing may occur in the UV curable adhesive, so the adhesive layer 14 is preferably a thermosetting adhesive. Also, from the viewpoint of screen printing suitability, the adhesive layer 14 is preferably a thermosetting adhesive.

[0046] The first adhesive layer 14a and the third adhesive layer 14c may be the same adhesive. The second adhesive layer 14b and the fourth adhesive layer 14d may be formed of the same adhesive.

[0047] (2-2) Detection circuit 20 The detection circuit 20 includes a first wiring 21, a second wiring 22, and a controller 23.

[0048] (2-2-1) First wiring 21 and second wiring 22 The first wiring 21 connects each of a plurality of first electrode pattern groups connected to each other by row wiring to the controller 23. The second wiring 22 connects each of a plurality of second electrode pattern groups connected to each other by column wiring to the controller 23.

[0049] (2-2-2) Controller 23 The controller 23 is implemented by a computer. The controller 23 comprises a control arithmetic unit and a memory device (neither of which are shown in the diagram). The control arithmetic unit is a processor such as a CPU or GPU. The control arithmetic unit reads a program stored in the memory device and performs pressure detection processing according to this program. Furthermore, the control arithmetic unit writes the calculation results to the memory device and reads information stored in the memory device according to the program.

[0050] In the shear force and pressure detection process, the controller 23 drives each second electrode pattern group at different timings and measures the capacitance between each first electrode pattern group and the second electrode pattern. Based on the measured capacitance, the controller 23 detects the magnitude of the load P and its position on the pressure sensor sheet 10. The controller 23 also performs multi-point detection of the magnitude of the load P and its position on the pressure sensor sheet 10.

[0051] (3) Method for manufacturing the pressure sensor sheet 10 The method for manufacturing the pressure sensor sheet 10 comprises a first step ST1, a second step ST2, a third step ST3, and a fourth step ST4. Figure 2 is a diagram showing the steps of the method for manufacturing the pressure sensor sheet 10. Figures 3A and 3B are diagrams showing the method for manufacturing the pressure sensor sheet 10.

[0052] For convenience, the adhesive used in the first adhesive layer 14a will be referred to as the first adhesive, the adhesive used in the second adhesive layer 14b will be referred to as the second adhesive, the adhesive used in the third adhesive layer 14c will be referred to as the third adhesive, and the adhesive used in the fourth adhesive layer 14d will be referred to as the fourth adhesive. The first, second, third, and fourth adhesives may all be the same adhesive, or they may differ in some respects.

[0053] (3-1) First Step ST1 In the first step ST1, a first adhesive layer 14a, which is a first adhesive in a semi-cured state, is laminated onto the first surface S1 of the foam layer 13, and a third adhesive layer 14c, which is a third adhesive in a semi-cured state, is laminated onto the second surface S2 of the foam layer 13. More specifically, the first step ST1 includes the steps of applying the first adhesive to the first surface S1 of the foam layer 13, applying the third adhesive to the second surface S2 of the foam layer 13, and semi-curing the first and third adhesives to form the first adhesive layer 14a and the third adhesive layer 14c laminated on the foam layer 13 (Figure 3A). The first step ST1 is an example of the first adhesive layer lamination step.

[0054] In this disclosure, "semi-cured state" refers to the state from when the curing of the adhesive begins until it is completely cured. As the viscosity of the adhesive increases as it hardens, keeping the first adhesive in a semi-cured state prevents it from penetrating into the foam layer due to external pressure applied in subsequent processes. The semi-cured state is preferably one in which the adhesive is dry enough that it does not stick to the finger when touched. In the cross-section of the finished pressure sensor sheet 10, it is preferable that the first adhesive is semi-cured to the extent that a boundary line can be observed between the first adhesive and the second adhesive laminated on the first adhesive.

[0055] The first adhesive layer 14a, which is a semi-cured first adhesive, and the third adhesive layer 14c, which is a semi-cured third adhesive, can be formed, for example, if the first and third adhesives are two-component thermosetting adhesives, by leaving them in an environment at room temperature (e.g., 5°C to 35°C) for about 24 hours or by heating them in an environment at 40°C for about 3 hours. If the first and third adhesives are moisture-curing adhesives, the first and third adhesive layers 14a and 14c can be formed in a semi-cured state by leaving them at room temperature with a humidity of 40% or less for about 24 hours. Furthermore, if the first and third adhesives are UV-curing adhesives, the first and third adhesive layers 14a and 14c can be formed in a semi-cured state by irradiating them with about half the exposure amount required to complete curing. Note that the curing method for bringing the adhesive to a semi-cured state is not limited to heating, and a known method can be selected depending on the type of adhesive.

[0056] (3-2) Second Step ST2 In the second step ST2, the first electrode layer 11b is laminated onto the first adhesive layer 14a via the second adhesive layer 14b, which is the second adhesive. More specifically, the second step ST2 includes the steps of applying the second adhesive to the first adhesive layer 14a to form the second adhesive layer 14b, and attaching the first electrode sheet 11, which includes the first electrode layer 11b, to the second adhesive layer 14b (Figure 3B). The second step ST2 is an example of a layer lamination process.

[0057] (3-3) Third step ST3 In the third step ST3, the second electrode layer 12b is laminated onto the third adhesive layer 14c via the fourth adhesive layer 14d, which is the fourth adhesive. More specifically, the third step ST3 includes the steps of applying the fourth adhesive to the third adhesive layer 14c to form the fourth adhesive layer 14d, and attaching the second electrode sheet 12, which includes the second electrode layer 12b, to the fourth adhesive layer 14d (Figure 3B).

[0058] (3-4) Fourth step ST4 In the fourth step ST4, the adhesive layer 14 is cured. More specifically, the fourth step ST4 includes a step of curing the adhesive layer 14 by a known curing method. The curing method of the adhesive can be selected from known methods depending on the type of adhesive. For example, if it is a thermosetting adhesive, it can typically be cured by heating. In this case, the air pressure in the heating atmosphere may be increased, or pressure may be applied to the pressure sensor sheet 10. The fourth step ST4 is an example of a curing step.

[0059] In the manufacturing method for the pressure sensor sheet 10, a semi-cured first adhesive layer 14a is formed on the foam layer 13 in the first step ST1. Because of the semi-cured first adhesive layer 14a formed in the first step ST1, the penetration of the second adhesive into the foam layer 13 by the pressure applied from the outside in the second step ST2 and the fourth step ST4 is suppressed.

[0060] (4) Modified Examples (4-1) Modified Example 1 In the first step ST1, the first adhesive layer 14a may be laminated onto the foam layer 13 using a release film 15. Figures 4A, 4B, and 4C show the first step ST1 according to Modified Example 1. More specifically, the first step ST1 may include the steps of applying the first adhesive to the release film 15, forming the first adhesive layer 14a on the release film 15 with the first adhesive in a semi-cured state (Figure 4A), attaching the foam layer 13 to the first adhesive layer 14a (Figure 4B), and peeling the release film 15 from the first adhesive layer 14a (Figure 4C). A detailed explanation is omitted, but the third adhesive layer 14c may also be laminated onto the foam layer 13 in a similar manner.

[0061] The viscosity of the adhesive in a semi-cured state is greater than the viscosity of the adhesive before semi-curing, and the semi-cured adhesive does not easily penetrate the foam layer 13. Therefore, by curing the adhesive to a semi-cured state on the release film 15, it is possible to suppress the penetration of the adhesive into the foam layer 13.

[0062] (4-2) Modification 2 In the second step ST2, the second adhesive layer 14b may be formed by first forming it on the first electrode layer 11b and then attaching it to the first adhesive layer 14a together with the first electrode layer 11b. Figure 5 shows the second step ST2 according to Modification 2. More specifically, the second step ST2 may include the steps of applying the second adhesive to the first electrode sheet 11 including the first electrode layer 11b to form the second adhesive layer 14b, and attaching the second adhesive layer 14b to the first adhesive layer 14a. A detailed explanation is omitted, but in the third step ST3, the fourth adhesive layer 14d may also be attached to the third adhesive layer 14c in a similar manner.

[0063] Multiple first electrode patterns are formed on the first electrode sheet 11, and gaps exist between each electrode pattern. By directly applying adhesive to the first electrode sheet in this way, the adhesive can easily penetrate into the gaps between the first electrode patterns, resulting in good adhesion between the first electrode sheet 11 and the second adhesive layer 14b.

[0064] (4-3) Modification 3 In the first step ST1, the first adhesive layer 14a may be laminated onto the foam layer 13 using an adhesive film. More specifically, the first step ST1 may include a step in which an adhesive film formed from a first adhesive in a semi-cured state is laminated onto the foam layer 13. A detailed explanation is omitted, but the third adhesive layer 14c may also be laminated onto the foam layer 13 in a similar manner. The adhesive film is a film-like adhesive. The adhesive film is, for example, an unstretched polypropylene film, which is laminated onto the foam layer 13 by dry lamination.

[0065] The viscosity of the adhesive film formed with the semi-cured adhesive is higher than that of the uncured adhesive, making it difficult for the adhesive film to penetrate the foam layer 13. Therefore, by forming the first adhesive layer 14a using the adhesive film, the penetration of the adhesive into the foam layer 13 can be suppressed.

[0066] (4-4) Modification 4 The controller 23 may be capable of detecting the shear force (shear stress) acting on the pressure sensor sheet 10 based on the measured capacitance. In other words, the pressure sensor 100 may be used as a shear force sensor.

[0067] (4-5) Modification 5 The layer bonded to the foam layer 13 via the first adhesive layer 14a and the second adhesive layer 14b is not limited to a layer containing electrodes, but may be, for example, an elastic layer. Similarly, the layer bonded to the foam layer 13 via the first adhesive layer 14a and the second adhesive layer 14b is not limited to a layer containing electrodes, but may be, for example, an elastic layer.

[0068] (4-6) Modification 6 The foam layer 13 may include an adhesive-penetrating layer 13b into which the adhesive, which is the first adhesive layer 14a, has permeated. The thickness of the adhesive-penetrating layer 13b relative to the thickness of the foam layer 13 is, for example, 0 percent or more and 30 percent or less, and from the viewpoint of suppressing variations in detection sensitivity, it is preferably 20 percent or less. Figure 6 is a cross-sectional view of a pressure sensor sheet 10a according to Modification 6.

[0069] (4-7) Modification 7 The pressure sensor 100 may be a single-point detection sensor.

[0070] (5) Features (5-1) The method for manufacturing the pressure sensor sheet 10 comprises a first step ST1 (first adhesive layer lamination step), a second step ST2 (adhesive layer lamination step), and a fourth step ST4 (curing step). In the first step ST1, a first adhesive layer 14a, which is a first adhesive in a semi-cured state, is laminated onto the foam layer 13. In the second step ST2, a first electrode layer 11b (adhesive layer) is laminated onto the first adhesive layer 14a via a second adhesive layer 14b, which is a second adhesive. In the curing step, the first adhesive layer 14a and the second adhesive layer 14b are cured.

[0071] In the manufacturing method for the pressure sensor sheet 10, a semi-cured first adhesive layer 14a is formed on the foam layer 13 in the first step ST1 (first adhesive layer lamination step). Because of the semi-cured first adhesive layer 14a formed in the first step ST1, penetration of the second adhesive into the foam layer 13 is suppressed in the second step ST2 and the fourth step ST4.

[0072] Adhesive that penetrates the foam layer 13 unevenly hardens, hindering the uniform deformation of the foam layer 13 and causing variations in the detection sensitivity of the pressure sensor sheet 10. Even if the adhesive penetrates uniformly, the amount of deformation of the foam layer 13 as a whole decreases due to the adhesive that penetrates the foam layer 13, resulting in a decrease in the detection sensitivity of the pressure sensor sheet 10, or individual differences in detection sensitivity between products with different penetration amounts.

[0073] According to the manufacturing method for the pressure sensor sheet 10, the penetration of adhesive into the foam layer 13 is suppressed, thereby suppressing variations in detection sensitivity, decreases in detection sensitivity, and individual differences in detection sensitivity between products in the manufactured pressure sensor sheet 10 and the pressure sensor 100 using it.

[0074] (5-2) The first step ST1 may include the steps of applying a first adhesive to the foam layer 13 and partially curing the first adhesive by a known method such as heating to form a first adhesive layer 14a laminated on the foam layer 13.

[0075] (5-3) The first step ST1 may include the steps of applying a first adhesive to the release film 15, forming a first adhesive layer 14a by allowing the first adhesive to reach a semi-cured state, attaching the foam layer 13 to the first adhesive layer 14a, and peeling the release film 15 from the first adhesive layer 14a. By allowing the adhesive to cure to a semi-cured state on the release film 15, the foam layer 13 does not come into contact with the uncured adhesive with low viscosity, thus suppressing the penetration of the adhesive into the foam layer 13.

[0076] (5-4) The second step ST2 may include the steps of applying the second adhesive to the first adhesive layer 14a to form the second adhesive layer 14b, and attaching the first electrode layer 11b to the second adhesive layer 14b.

[0077] (5-5) The second step ST2 may include the steps of applying the second adhesive to the first electrode layer 11b to form the second adhesive layer 14b, and attaching the second adhesive layer 14b to the first adhesive layer 14a. In this way, the adhesive can easily penetrate into the gaps between the first electrode patterns, resulting in good adhesion between the first electrode sheet 11 and the second adhesive layer 14b.

[0078] (5-6) The first step ST1 may include a step of laminating an adhesive film formed with the first adhesive in a semi-cured state onto the foam layer 13. In this way, the uncured adhesive with low viscosity does not come into contact with the foam layer 13, and thus the penetration of the adhesive into the foam layer 13 can be suppressed.

[0079] (5-7) The pressure sensor sheet 10 comprises a foam layer 13, a first adhesive layer 14a laminated on the foam layer 13, a second adhesive layer 14b laminated on the first adhesive layer 14a, and a layer to be bonded to the foam layer 13 via the first adhesive layer 14a and the second adhesive layer 14b (for example, a first electrode layer 11b).

[0080] (5-8) The pressure sensor sheet 10 may further include a third adhesive layer 14c laminated on the side of the foam layer 13 opposite to the side on which the first adhesive layer 14a is laminated (for example, the first side S1) (for example, the second side S2), and a fourth adhesive layer 14d laminated on the third adhesive layer 14c.

[0081] (5-9) The first adhesive layer 14a and the third adhesive layer 14c may be the same adhesive. The second adhesive layer 14b and the fourth adhesive layer 14d may be the same adhesive.

[0082] (5-10) The foam layer 13 may include an adhesive-penetrating layer 13b into which the adhesive, which is the first adhesive layer 14a, has permeated. The thickness of the adhesive-penetrating layer 13b relative to the thickness of the foam layer 13 may be 0 percent or more and 30 percent or less.

[0083] (5-11) The pressure sensor 100 is equipped with a pressure sensor sheet 10.

[0084] <Conclusion> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple modifications described herein can be arbitrarily combined as needed.

[0085] 10: Sheet for pressure sensor 11: First electrode sheet 11a: First insulating sheet 11b: First electrode layer (adhesive layer) 12: Second electrode sheet 12a: Second insulating sheet 12b: Second electrode layer 13: Foam layer 13a: Bubbles 13b: Adhesive penetration layer 14: Adhesive layer 14a: First adhesive layer 14b: Second adhesive layer 14c: Third adhesive layer 14d: Fourth adhesive layer 15: Release film 20: Detection circuit 21: First wiring 22: Second wiring 23: Controller 100: Pressure sensor S1: First surface S2: Second surface P: Load

Claims

1. A method for manufacturing a pressure sensor sheet, comprising: a first adhesive layer lamination step of laminating a first adhesive layer, which is a first adhesive in a semi-cured state, onto a foam layer; a layer to be laminated onto the first adhesive layer via a second adhesive layer, which is a second adhesive; and a curing step of curing the first adhesive layer and the second adhesive layer.

2. The method for manufacturing a pressure sensor sheet according to claim 1, wherein the first adhesive layer lamination step includes the steps of applying the first adhesive to the foam layer and partially curing the first adhesive to form the first adhesive layer laminated on the foam layer.

3. The method for manufacturing a pressure sensor sheet according to claim 1, wherein the first adhesive layer lamination step includes the steps of: applying the first adhesive to a release film; forming the first adhesive layer by allowing the first adhesive to be in a semi-cured state; attaching the foam layer to the first adhesive layer; and peeling the release film from the first adhesive layer.

4. The method for manufacturing a pressure sensor sheet according to claim 2 or 3, wherein the bonding layer lamination step includes the steps of: applying the second adhesive to the first adhesive layer to form the second adhesive layer; and attaching the bonding layer to the second adhesive layer.

5. The method for manufacturing a pressure sensor sheet according to claim 2 or 3, wherein the bonding layer lamination step includes the steps of applying the second adhesive to the bonding layer to form the second adhesive layer, and attaching the second adhesive layer to the first adhesive layer.

6. The method for manufacturing a pressure sensor sheet according to claim 1, wherein the first adhesive layer lamination step includes laminating an adhesive film formed of the first adhesive in a semi-cured state onto the foam layer.

7. The method for manufacturing a pressure sensor sheet according to claim 1, wherein the adhesive layer is an electrode layer.

8. A pressure sensor sheet comprising: a foam layer; a first adhesive layer laminated on the foam layer; a second adhesive layer laminated on the first adhesive layer; and an adhesive layer bonded to the foam layer via the first and second adhesive layers.

9. The pressure sensor sheet according to claim 8, further comprising a third adhesive layer laminated on the side of the foam layer opposite to the side on which the first adhesive layer is laminated, and a fourth adhesive layer laminated on the third adhesive layer.

10. The pressure sensor sheet according to claim 8, wherein the adhesive layer is an electrode layer.

11. The pressure sensor sheet according to claim 9, wherein the first adhesive layer and the third adhesive layer are made of the same adhesive, and the second adhesive layer and the fourth adhesive layer are made of the same adhesive.

12. The pressure sensor sheet according to claim 8, wherein the foam layer includes an adhesive-penetrating layer into which the adhesive that is the first adhesive layer has permeated, and the thickness of the adhesive-penetrating layer relative to the thickness of the foam layer is 0 percent or more and 30 percent or less.

13. A pressure sensor comprising a pressure sensor sheet according to any one of claims 8 to 12.

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