Capacitive Sensor

Abstract

In capacitive sensors, the detection range is expanded. [Solution] A capacitive sensor comprising a first electrode, a flexible member having dielectric and elastic properties, and a second electrode provided within the flexible member so as to face the first electrode while maintaining a distance between them, for detecting capacitance between the first electrode and the second electrode, wherein the flexible member has an electrode-containing portion that houses the second electrode and is spaced apart from the first electrode, and a plurality of columnar portions extending between the electrode-containing portion and the second electrode, and a filling portion in which a dielectric material with air bubbles is filled in the gap.

Description

[Technical Field]

[0001] The present invention relates to a capacitive sensor. [Background Art]

[0002] In realizing a tactile sensor for robots, it is required that while maintaining the flexibility of the surface, contact force between the sensor and the external environment can be detected ranging from minute forces to large forces. For this reason, the present inventors have proposed capacitive tactile sensors having a flexible electrode and a dielectric with a pillar structure (Patent Documents 1 and 2). [Prior Art Literature] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2024-086155 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2024-086156 [Patent Document 3] International Publication No. WO 2020 / 066121 [Patent Document 4] Japanese Unexamined Patent Application Publication No. 2021-018692 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, a fingertip tactile sensor for a robot hand that performs dexterous operations needs to detect not only minute forces but also high-density force distribution. In this case, the expected inter-electrode pitch is 1 / 3 that of the conventional art, and the electrode size is about 1 / 4 that of the conventional art. When the electrode area is reduced, the capacitance decreases, so that data cannot be acquired by the controller, or even if data can be acquired, the S / N ratio decreases. For this reason, it has been difficult to realize a flexible, high-sensitivity and high-density capacitive sensor. There is room for improvement in the prior art.

[0005] This invention has been made in view of the above circumstances, and aims to achieve the objective of providing a capacitive sensor that can expand the detection range while maintaining flexibility. [Means for solving the problem]

[0006] <1> A capacitive sensor according to one aspect of the present invention is First electrode (14), A flexible member (15A) having dielectric and elastic properties, A second electrode (13) is provided within the flexible member (15A) so as to face the first electrode (14) while maintaining a distance between it and the first electrode (14), and is used to detect the capacitance between the second electrode (13) and the first electrode (14). Equipped with, The aforementioned flexible member (15A) is The electrode housing portion (11) incorporates the second electrode (13) and is spaced apart from the first electrode (14), A plurality of columnar portions (15) extending between the electrode housing portion (11) and the second electrode (13), It has, The columnar portions (15) have a filled portion (17) in which a dielectric material containing air bubbles (17b) is filled in the gap (15a) between them. This resolved the above issues. <2> The capacitive sensor of the present invention is as described above. <1> In, Between the first electrode (14) and the second electrode (13), there is a high dielectric layer (18) made of a material with a higher dielectric constant than the flexible member (15A). It is possible. <3> The capacitive sensor of the present invention is as described above. <1> In, The filling portion (17) is made of a material with a higher dielectric constant than the flexible member (15A). It is possible.

[0007] the above <1> According to the invention described above, by having a filling portion made of a material with a higher dielectric constant than the flexible member between the first electrode, which is arranged along the surface of the substrate, and the second electrode, which is spaced apart from the first electrode, it is possible to direct more of the electric field emitted from one electrode to the other electrode compared to when there is no filling portion. As a result, the dielectric constant between the first electrode and the second electrode can be improved compared to when there is no filling portion. Therefore, it becomes possible to increase the capacitance formed between the first electrode and the second electrode, and even with a small electrode size, it becomes possible to increase the change in capacitance when a minute force is applied, thereby expanding the range of detectable force. The first electrode may be placed on the surface of the substrate, or it may be formed inside a flexible member along the surface of the substrate.

[0008] the above <2> According to the invention described above, in addition to the filling portion, by having a high dielectric layer made of a material with a higher dielectric constant than the flexible member between the first electrode and the second electrode, the electric field emitted from one electrode can be directed more towards the other electrode compared to when the high dielectric layer is absent. As a result, the dielectric constant between the first electrode and the second electrode can be improved compared to when the high dielectric layer is absent. Therefore, it becomes possible to increase the capacitance formed between the first electrode and the second electrode, and even with a small electrode size, it becomes possible to increase the change in capacitance when a minute force is applied, thereby expanding the range of detectable force.

[0009] According to the invention described in the above <3>, originally, the dielectric constant of the space formed between the pillar portions originates from air, and by locating the filling portion, which has a higher dielectric constant than air, between the first electrode and the second electrode, the dielectric constant between the first electrode and the second electrode can be increased. Accordingly, more electric field emitted from one electrode can be directed to the other electrode, compared to the case where the filling portion is not provided. Therefore, compared to the case where the filling portion is not provided, the capacitance formed between the first electrode and the second electrode can be increased, and even if the electrode size is small, it is possible to increase the change in capacitance when a minute force is applied, thereby expanding the range of detectable forces.

Effects of the Invention

[0010] According to the present invention, even if the electrode size is small, it is possible to achieve the effect of increasing the change in capacitance when a minute force is applied, thereby expanding the range of detectable forces. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] [Figure 1] It is a schematic cross-sectional view showing a first embodiment of a capacitive sensor according to the present invention. [Figure 2] It is a schematic cross-sectional view showing dimensions of a conventional capacitive sensor. [Figure 3] It is a schematic cross-sectional view showing an electric field in the first embodiment of the capacitive sensor according to the present invention. MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, a first embodiment of a capacitive sensor according to the present invention will be described with reference to the drawings. Figure 1 is a schematic cross-sectional view showing a capacitive sensor according to the present embodiment, and in the figure, reference numeral 10 denotes a capacitive sensor.

[0013] The capacitive sensor 10 according to the present embodiment includes an electrode built-in portion 11, a substrate 12, a transmission electrode (second electrode) 13, a reception electrode (first electrode) 14, a pillar (column portion) 15, and a foam portion (filling portion) 17, as shown in FIG. 1.

[0014] The electrode built-in portion 11 is disposed along the surface of the substrate 12. The electrode built-in portion 11 is disposed to face the substrate 12. The electrode built-in portion 11 is disposed substantially parallel to the surface of the substrate 12. The electrode built-in portion 11 is spaced apart from the surface of the substrate 12. The electrode built-in portion 11 includes a plurality of transmission electrodes 13. The substrate 12 is plate-shaped. The substrate 12 may have a planar shape or a curved shape. The substrate 12 may be formed of a material harder than a flexible member 15A described later. The substrate 12 may also be a printed circuit board or the like. The substrate 12 may be formed of the flexible member 15A described later. A plurality of reception electrodes 14 are disposed along the surface of the substrate 12.

[0015] A plurality of transmission electrodes 13 are disposed on substantially the same plane. The plurality of transmission electrodes 13 are on the same layer. The same layer means that they are disposed at substantially the same distance from the surface of the substrate 12. The plurality of transmission electrodes 13 are spaced apart from each other. Each of the plurality of transmission electrodes 13 has substantially the same contour shape. Each of the plurality of transmission electrodes 13 has the same area. When viewed in plan, the separation distances between adjacent transmission electrodes 13 are all equal. Each of the transmission electrodes 13 faces the corresponding reception electrode 14. Each of the transmission electrodes 13 corresponds to the corresponding reception electrode 14. When viewed in plan, the transmission electrodes 13 are each disposed so as to overlap with the corresponding reception electrode 14.

[0016] Multiple receiving electrodes 14 are arranged along the surface of the substrate 12. Multiple receiving electrodes 14 are arranged on substantially the same plane. Multiple receiving electrodes 14 are on the same hierarchical level. Multiple receiving electrodes 14 are spaced apart from each other. Multiple receiving electrodes 14 all have substantially the same contour shape. Multiple receiving electrodes 14 all have substantially the same area. When viewed from above, the distance between adjacent receiving electrodes 14 is equal. When viewed from above, the distance between adjacent receiving electrodes 14 is equal to the distance between adjacent transmitting electrodes 13. A wiring section (not shown) is connected to the transmitting electrode 13 and the receiving electrode 14, and this wiring section is connected to a control unit (not shown). The control unit can detect the capacitance between the transmitting electrode 13 and the receiving electrode 14.

[0017] The pillars 15 connect the electrode-embedded section 11 and the substrate 12 in the stacking direction. Multiple pillars 15 are formed on the surface of the substrate 12. The multiple pillars 15 are spaced apart from each other. When viewed from above, all of the multiple pillars 15 have substantially the same cross-sectional contour shape. All of the multiple pillars 15 have substantially the same area. All of the multiple pillars 15 have substantially the same cross-sectional shape along their entire axial length in the direction away from the surface of the substrate 12. When viewed from above, the spacing distance between adjacent pillars 15 is equal.

[0018] The cross-sectional contour shape of the pillar 15 in plan view can be the same as the contour shape of the transmitting electrode 13. The cross-sectional contour shape of the pillar 15 in plan view may be larger than the contour shape of the transmitting electrode 13. When viewed from above, the distance between adjacent pillars 15 may be equal to the distance between adjacent transmitting electrodes 13. When viewed from above, the distance between adjacent pillars 15 may be greater than the distance between adjacent transmitting electrodes 13. When viewed from above, the distance between adjacent pillars 15 may be less than the distance between adjacent transmitting electrodes 13. Pillar 15 may have wiring sections (not shown) formed therein.

[0019] The electrode housing portion 11 and the pillar 15 are formed from a dielectric and flexible, elastically deformable elastomer. The electrode housing portion 11 and the pillar 15 are formed from a flexible member 15A made of the same material. The electrode housing portion 11 and the pillar 15 are formed integrally. The pillar 15 can be bonded to the substrate 12 by an adhesive layer (not shown) made of the same material as the flexible member 15A. Alternatively, an electrode-embedded layer containing a receiving electrode 14, formed from a flexible member 15A, can be formed on the surface of the substrate 12. Furthermore, the substrate 12 can also be formed from a flexible material 15A.

[0020] The flexible member 15A is formed from a flexible dielectric material such as silicone rubber, polyvinyl chloride (PVC) gel, polyvinylidene fluoride (PVDF), polydimethylsiloxane (PDMS), silicone resin, urethane resin, epoxy resin, styrene resin, or composite materials thereof. For example, the flexible member 15A can be made from a material with a dielectric constant of approximately ε = 1.4 F / m. The flexible member 15A can have material properties such as superelasticity, flexibility, stretchability, being a material containing fluids or bubbles, or being a material containing gases.

[0021] Furthermore, both the transmitting electrode 13 and the receiving electrode 14 are made of a flexible conductor. The transmitting electrode 13 and the receiving electrode 14 can be formed from a material that contains an additive that changes the conductivity or dielectric constant, in addition to the same flexible member 15A as the electrode housing part 11 and the pillar 15. The wiring connected to the transmitting electrode 13 and the receiving electrode 14 can also be formed from the same material. The transmitting electrode 13 and the receiving electrode 14 may be formed, for example, by mixing conductive powder into the flexible member 15A. The transmitting electrode 13 and the receiving electrode 14 may be formed from a silicon-based resin mixed with conductors such as carbon, carbon nanofibers, or graphite, a silicon-based resin containing metal conductive fillers such as silver or copper, a thiophene-based conductive polymer, a conductive resin such as polystyrene sulfonic acid (PSS), or a composite material thereof.

[0022] Multiple pillars 15 are erected between the electrode-embedded section 11 and the substrate 12. A gap 15a is formed between the multiple pillars 15. The gap 15a is filled by the foam portion 17. The foam portion 17 is formed from a high dielectric material containing air bubbles 17b. By incorporating air bubbles 17b, the foam portion 17 is more flexible than the pillar 15. Because the foam portion 17 has sufficient flexibility, it does not hinder the elastic deformation of the pillar 15.

[0023] The foam portion 17 may be formed to have a high dielectric constant by mixing a high dielectric material such as graphite, titanium oxide (TiO2), or barium titanate (BaTiO3) into the flexible member 15A. Furthermore, the foam portion 17 can be configured so that the size and density of the bubbles 17b can be used as a sensor to determine whether they can maintain their shape, that is, the amount that can be mixed in can be within the range in which the flexible material can harden. The dielectric constant ε in the foam portion 17 is exemplified below. Graphite (ε = 12~13) • TiO2 (ε = 80~180) • BaTiO3 (ε = 1000~5000)

[0024] In this embodiment, when no external load F is applied to the capacitive sensor 10, the overlapping area of ​​the transmitting electrode 13 and the receiving electrode 14, viewed from above, is S. Furthermore, when no external load F is applied, the distance between the transmitting electrode 13 and the receiving electrode 14 is d. When no external load F is applied, if the capacitance between the transmitting electrode 13 and the receiving electrode 14 is C, then the capacitance C is expressed by the following formula. C = ε·S / d

[0025] When an external load F is applied, the electrode housing 11 and the pillar 15 deform. The pillar 15 deforms in accordance with the direction of the external load F. If the external load F compresses the transmitting electrode 13 and the receiving electrode 14, the distance d between the transmitting electrode 13 and the receiving electrode 14 changes. Alternatively, if the external load F separates the transmitting electrode 13 and the receiving electrode 14, the distance d between the transmitting electrode 13 and the receiving electrode 14 changes. In these cases, the capacitance C between the transmitting electrode 13 and the receiving electrode 14 changes. By detecting this change in capacitance, it becomes possible to measure the external load F.

[0026] Alternatively, when an external load F is applied in a direction along the substrate 12, the transmitting electrode 13 shifts relative to the receiving electrode 14, and the area S over which the transmitting electrode 13 overlaps the receiving electrode 14 changes to area S-Δ. As a result, the capacitance C between the transmitting electrode 13 and the receiving electrode 14 changes. By detecting this change in capacitance, it becomes possible to measure the external load F.

[0027] Furthermore, the external load F can be in a direction not only normal to the surface of the substrate 12 or along the surface of the substrate 12, but also in a direction that is inclined at an angle. In this case, a change in the distance d between the electrodes and a change in the overlapping area S occur simultaneously. Consequently, the capacitance C between the transmitting electrode 13 and the receiving electrode 14 changes. By detecting this change in capacitance, it becomes possible to measure the external load F.

[0028] Figure 2 is a schematic cross-sectional view illustrating the dimensions of a capacitive sensor. In conventional capacitive sensors, the electrode size was approximately 4 mm for the pitch p between identical electrodes and approximately 2 mm square for the electrode size S. In contrast, the electrode size of the capacitive sensor 10 of this embodiment is approximately 1.5 mm for the pitch p between transmitting electrodes 13 and approximately 2 mm square for the transmitting electrode size S, or approximately 1 mm square or Φ1 mm.

[0029] As with the capacitive sensor 10 of this embodiment, reducing the electrode size reduces the number of electric field lines FS from the transmitting electrode 13 to the receiving electrode 14, as shown in Figure 2. Furthermore, reducing the electrode size reduces the capacitance C between one pair of transmitting electrodes 13 and receiving electrodes 14 compared to conventional electrode sizes. Consequently, the sensor sensitivity deteriorates, and the magnitude of detectable external loads increases. In other words, it becomes impossible to detect small forces.

[0030] However, in the capacitive sensor 10 of this embodiment, a foam portion 17 made of a high dielectric material is placed between the transmitting electrode 13 and the receiving electrode 14. As a result, the dielectric constant ε between the transmitting electrode 13 and the receiving electrode 14 is increased. From the above equation for capacitance C, it can be seen that as ε increases, capacitance C also increases. As a result, as shown in Figure 1, the number of electric field lines FS from the transmitting electrode 13 to the receiving electrode 14 can be increased. Therefore, sensitivity to changes in capacitance C is improved, and the magnitude of detectable external loads can be reduced. In other words, small forces can be detected. That is, the sensitivity as a sensor characteristic can be improved. Specifically, the capacitive sensor 10 of this embodiment can detect forces that come into contact with the outside world, i.e., external loads F, ranging from minute forces of about 0.02 N to large forces of the order of 1 N.

[0031] To manufacture the capacitive sensor 10 of this embodiment, a substrate 12 on which a receiving electrode 14 is formed is prepared. An electrode housing 11 including a transmitting electrode 13 is also formed. At this time, a plate body formed from a flexible member 15A having a recess corresponding to the transmitting electrode 13 can be formed using a mold, and then the transmitting electrode 13 can be formed using the flexible member 15A with conductive particles mixed into the recess of this plate body. Alternatively, a transmitting electrode 13 of a predetermined shape can be formed in a predetermined position first, and then the electrode housing 11 can be formed integrally so as to cover the transmitting electrode 13. Next, using a mold corresponding to the pillar 15, the pillar 15 is formed so as to be integrated with the electrode housing 11, which includes the transmitting electrode 13.

[0032] Next, a foam portion 17 is formed between the multiple pillars 15 using a flexible member 15A containing high dielectric particles. In this case, the foam portion 17 can be hardened after coating, filling, or press-fitting. The foam portion 17 may have a foaming agent or foam-forming agent added to it before filling in order to form the necessary bubbles 17b. As the foaming agent, a chemical foaming agent, a physical foaming agent, or foam beads can be used. As the foam-forming agent, one can be used that contains soluble particles such as sugar, is formed into a predetermined shape, and then these soluble particles are dissolved by washing with water to form voids. The end of the pillar 15 is connected to the substrate 12 to manufacture the capacitive sensor 10.

[0033] Alternatively, after connecting the end of the pillar 15 to the substrate 12, the foam portion 17 can be filled into the gap 15a formed between the electrode-embedded portion 11 and the substrate 12.

[0034] In this embodiment, the capacitive sensor 10 has a high density arrangement of transmitting electrodes 13 and receiving electrodes 14, each with an electrode size of approximately 1 mm square or Φ1 mm and an electrode pitch ps of approximately 1.5 mm, which can be easily changed relative to each other by flexible pillars 15 and foam portions 17. Therefore, the capacitance C between each pair of electrodes can be reduced, making it possible to detect minute external load distributions F without reducing the signal-to-noise ratio. Thus, it is possible to provide a capacitive sensor with minute and delicate sensor sensitivity that can be applied to parts corresponding to fingertips rather than palms, for example, as a tactile sensor for robots. Specifically, it can detect forces from approximately 0.02 N to approximately 1 N.

[0035] A second embodiment of the capacitive sensor according to the present invention will be described below with reference to the drawings. Figure 3 is a schematic cross-sectional view showing the capacitive sensor in this embodiment. The difference in this embodiment from the first embodiment described above lies in the high dielectric layer; other components corresponding to those in the first embodiment described above are denoted by the same reference numerals and their descriptions are omitted.

[0036] As shown in Figure 3, the capacitive sensor 10 in this embodiment has an interlayer portion (high dielectric layer) 18. The interlayer portion 18 is provided in the electrode-integrated portion 11. The interlayer portion 18 is provided in a position closer to the transmitting electrode 13 than to the receiving electrode 14. The interlayer portion 18 is provided in a position closer to the transmitting electrode 13 than to the pillar 15. The interlayer section 18 increases the number of electric field lines FS extending from the transmitting electrode 13 to the receiving electrode 14. The interlayer section 18 directs as many electric fields as possible from the transmitting electrode 13 to the receiving electrode 14. For this reason, it is preferable that the interlayer section 18 be as close to the transmitting electrode 13 as possible. The interlayer section 18 can also be in contact with the transmitting electrode 13.

[0037] The interlayer portion 18 is positioned so as to overlap all of the transmitting electrodes 13 when viewed from above. Furthermore, the interlayer portion 18 is positioned in a region that includes all of the outermost transmitting electrodes 13 when viewed from above. The interlayer portion 18 is formed in the same area as the region formed by connecting the contours of the outermost transmitting electrodes 13 when viewed from above. The interlayer portion 18 may be formed in a region larger than the region formed by connecting the contours of the outermost transmitting electrodes 13 when viewed from above. The interlayer portion 18 may be formed over the entire surface of the electrode-embedded portion 11 when viewed from above. As a result, the interlayer portion 18 increases the number of electric field lines FS extending from the transmitting electrode 13 to the receiving electrode 14. In particular, it directs electric field lines extending from the side position of the transmitting electrode 13 to the receiving electrode 14, which act as so-called fringes, towards the corresponding receiving electrode 14. For this reason, the interlayer portion 18 is formed from a material with a high dielectric constant.

[0038] The interlayer portion 18 may be formed to have a high dielectric constant by mixing graphite, titanium oxide (TiO2), and barium titanate (BaTiO3) into the flexible member 15A, similar to the foam portion 17. Furthermore, unlike the foam portion 17, the interlayer portion 18 does not contain air bubbles. Furthermore, the interlayer portion 18 can have the same flexibility as the electrode-embedded portion 11.

[0039] The thickness of the interlayer portion 18 is uniform across its entire surface when viewed from above. Since increasing the thickness of the interlayer portion 18 increases the distance d between electrodes, it is preferable to keep it as small as possible. The thickness of the interlayer portion 18 can be set so that the capacitance C between the transmitting electrode 13 and the receiving electrode 14 is approximately the same when the interlayer portion 18 is provided and the gap 15a is not filled with foam portion 17, and when the interlayer portion 18 is absent and the gap 15a is filled with foam portion 17.

[0040] To manufacture the capacitive sensor 10 of this embodiment, since the layers of the interlayer portion 18 are different from those of the transmitting electrode 13, it is possible to add a step of laminating the material that will become the interlayer portion 18 when forming the electrode-embedded portion 11.

[0041] In the capacitive sensor 10 of this embodiment, an interlayer portion 18 made of a high dielectric material is arranged between the transmitting electrode 13 and the receiving electrode 14, in addition to the foam portion 17. This allows the dielectric constant ε between the transmitting electrode 13 and the receiving electrode 14 to be further increased compared to the first embodiment. Therefore, sensitivity to changes in capacitance C is improved, and the magnitude of detectable external loads can be reduced. In other words, small forces can be detected. That is, the sensitivity as a sensor characteristic can be improved. A flexible, highly sensitive, and high-density capacitive sensor can be realized.

[0042] Furthermore, in the present invention, it is also possible to individually select and combine each of the configurations in the above-described embodiments.

[0043] In particular, the capacitive sensor 10 of the present invention can be configured in which an interlayer portion 18 is provided and the gap 15a is not filled with a foam portion 17.

[0044] The following explains the structural differences in each configuration and their relationship to sensor characteristics.

[0045] [Table 1]

[0046] In the table, the conventional structure has a pitch p between identical electrodes of approximately 4 mm and an electrode size S of approximately 2 mm square. The structure of the interlayer section, the structure of the foam section, and the structure of the interlayer section + foam section all have a pitch p between transmitting electrodes 13 of approximately 1.5 mm and a transmitting electrode size S of approximately 2 mm square, or 1 mm square or Φ1 mm. Furthermore, the structure of the interlayer portion is such that an interlayer portion 18 is provided, and the gap 15a is not filled with foam portion 17. The structure of the foam portion is the same as in the first embodiment, with the foam portion 17 filling the gap 15a and no interlayer portion 18 provided. The structure of the interlayer portion + foam portion is the same as in the second embodiment, with the foam portion 17 filling the gap 15a and the interlayer portion 18 being provided.

[0047] In conventional structures, the characteristic low-to-medium density corresponds to the number of electrodes per unit area where the pitch p between identical electrodes is approximately 4 mm and the electrode size S is approximately 2 mm square. In the structure of the interlayer section, the characteristics of high density and flexibility correspond to the number of electrodes per unit area where the pitch p between transmitting electrodes 13 is approximately 1.5 mm, and the size S of the transmitting electrodes 13 is approximately 2 mm square, or approximately 1 mm square or Φ1 mm. Furthermore, the flexibility regarding deformation between the transmitting electrodes 13 and the receiving electrodes 14 is not affected because there is no foam section 17, and is due solely to the flexibility of the pillars 15.

[0048] In the structure of the foam section, the characteristics of high density and thinness correspond to the number of electrodes per unit area where the pitch p between transmitting electrodes 13 is about 1.5 mm, and the size S of the transmitting electrodes 13 is about 2 mm square, or about 1 mm square or Φ1 mm. Furthermore, because there is no thickness in the interlayer section 18, it means that the distance between the transmitting electrode 13 and the receiving electrode 14 is due solely to the pillar 15. In the structure of the interlayer section + foam section, the characteristics of high density and high sensitivity correspond to the number of electrodes per unit area where the pitch p between transmitting electrodes 13 is about 1.5 mm, and the size S of the transmitting electrodes 13 is about 2 mm square, or about 1 mm square or Φ1 mm. Furthermore, because it has both an interlayer section 18 and a foam section 17, it means that the dielectric constant of both is improved.

[0049] In the structure of the interlayer section, the structure of the foam section, and the structure of the interlayer section + foam section, "high density" corresponds to the number of electrodes per unit area where the pitch p between the transmitting electrodes 13 is about 1.5 mm, and the size S of the transmitting electrodes 13 is about 2 mm square, or about 1 mm square or Φ1 mm. In conventional structures, this corresponds to the number of electrodes per unit area where the pitch p between identical electrodes is approximately 4 mm and the electrode size S is approximately 2 mm square.

[0050] In the conventional structure, the sensitivity is poor, but in the interlayer structure and the foam structure, the sensitivity is good. This means that because the electrode size is small, even minute external loads can be detected, and the distribution of minute external loads along the sensor surface can also be detected. In the interlayer + foam structure, a double circle for sensitivity means that the electrode size is small, and the capacitance is increased by placing a high dielectric constant material between the electrodes, making it possible to detect even minute external loads and the distribution of minute external loads.

[0051] In conventional structures and foam structures, the overall thinness means that there is no increase in sensor thickness due to the interlayer portion 18. In the structure of the interlayer section and the structure of the interlayer section + foam section, the overall thickness being triangular means that there is an increase in sensor thickness due to the interlayer section 18.

[0052] In conventional structures and interlayer structures, flexibility is considered good because the gap 15a is not filled by the foam portion 17, and the sensor deformation that detects external loads is due solely to the pillar 15. In the structure of the foam section and the structure of the interlayer section + foam section, the flexibility being triangular means that the deformation of the pillar 15 that detects external loads is affected by the foam section 17 that fills the gap 15a.

[0053] In conventional structures, the number of wires is represented by a circle, while in the structure of the interlayer section, the structure of the foam section, and the structure of the interlayer section + foam section, the number of wires is represented by a triangle, which means that the number of wires needs to be increased or decreased depending on the number of electrodes.

[0054] In conventional structures, a double-check rating for ease of manufacturing means that the large electrode size makes manufacturing easy. In the structure of the interlayer, ease of manufacturing is considered a plus because the smaller electrode size leads to increased required precision. The reason why the ease of manufacturing is triangular in the structure of the foam section and the structure of the interlayer section + foam section is that the required precision increases due to the small electrode size, and in the manufacturing of the foam section 17, the number of processes increases because filling and foaming operations are required after the pillar 15 is molded. [Explanation of symbols]

[0055] 10…Capacitive Sensor 11…Electrode built-in section 12… Circuit board 13…Transmitting electrode (second electrode) 14…Receiving electrode (first electrode) 15... Pillar (column) 15A... Flexible material 15a...Gap 17…Foam section (filling section) 17b...Air bubbles 18…Interlayer section (high dielectric layer)

Claims

1. First electrode and, A flexible member having dielectric and elastic properties, A second electrode is provided within the flexible member so as to face the first electrode while maintaining a distance from it, and for detecting the capacitance between it and the first electrode, Equipped with, The aforementioned flexible member is An electrode housing portion that houses the second electrode and is spaced apart from the first electrode, A plurality of columnar portions extending between the electrode housing portion and the second electrode, It has, The gap between the columnar portions is filled with a dielectric material containing air bubbles, forming a filled portion. Capacitive sensor.

2. In the capacitive sensor according to claim 1, Between the first electrode and the second electrode, there is a high dielectric layer made of a material with a higher dielectric constant than the flexible member. Capacitive sensor.

3. In the capacitive sensor according to claim 1, The filling portion is made of a material with a higher dielectric constant than the flexible member. Capacitive sensor.

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