Shearing force sensor, inner force sensor sheet, and inner force sensor

Abstract

To provide a shearing force sensor capable of suppressing deformation in the compression direction and enhancing deformation in the shearing direction, and an inner force sensor sheet and an inner force sensor.SOLUTION: The shearing force sensor comprises a dielectric layer A composed of first to n-th soft layers (n≥2) and first to m-th hard layers (1≤m≤n-1, 1≤m≤n, or 1≤m≤n+1). The relationships Esoft,max<Ehard,min, εsoft,max<εhard,min, and tsoft,j>thard,admin are satisfied, where Esoft,max represents the maximum value of elastic modulus of the first to n-th soft layers, Ehard,min represents the minimum value of elastic modulus of the first to m-th hard layers, εsoft,max represents the maximum value of dielectric constant of the first to n-th soft layers, εhard,min represents the minimum value of dielectric constant of the first to m-th hard layers, tsoft,j represents the thickness of the j-th soft layer (1≤j≤n), and thard,admin represents the minimum value of thickness of the k-th hard layer adjacent to the j-th soft layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a shear force sensor, a force sensor sheet, and a force sensor, and more particularly to a shear force sensor capable of effectively detecting shear force, and a force sensor sheet and force sensor equipped with such a shear force sensor. [Background technology]

[0002] Measuring the forces acting on objects when people move or when robots work is an important issue in a wide range of fields, including ergonomics, production engineering, and medicine and welfare. Measuring these forces is thought to be useful, for example, for quantitative analysis of skilled workers' techniques, which rely heavily on intuition, and for the efficient transfer of skills. Furthermore, if robots could measure and recognize these forces, more precise movement and control would be possible. Force sensors are known as devices for measuring force. A "force sensor" is a sensor that can measure the magnitude and direction of force or torque by utilizing the deformation caused by the application of force to the object being measured.

[0003] Force sensors are widely used industrially, but bulk-type sensors such as load cells are the norm. On the other hand, when measuring human movements and tasks, a typical example is measuring the force when the person is grasping an object (i.e., in a gripping state). In this case, the sensor must not interfere with the person's movements. It is also desirable for robots to be able to flexibly recognize objects of various hardnesses. Bulk-type sensors such as load cells are not suitable for such purposes, and thin, flexible sheet-type sensors are considered preferable.

[0004] Various proposals have been made in the past regarding such flexible force sensors. For example, Patent Document 1 states: a laminated body in which a first insulating layer, a first conductive layer, a first dielectric layer, a second conductive layer, a second dielectric layer, a third conductive layer, and a second insulating layer are laminated in this order; the first conductive layer and the third conductive layer are electrically connected; The first and second dielectric layers have different hardness A capacitive sensor is disclosed.

[0005] The same document states: (A) When the hardness of the first dielectric layer and the second dielectric layer is different, the linearity of the change in thickness of the dielectric layer can be maintained regardless of the magnitude of the applied load, and (B) By maintaining the linearity of the change in the thickness of the dielectric layer, a capacitive sensor with a wide dynamic range can be realized in load measurement. is stated.

[0006] Patent Document 2 states: an insulating layer having a Poisson's ratio of 0 to 0.48; Two first electrodes formed on one surface of the insulating layer; Six second electrodes formed on the other surface of the insulating layer; A pressure sensor sheet comprising:

[0007] The same document states: (A) When a pressure is applied to the pressure sensor sheet, the change in capacitance that occurs between multiple electrodes at different positions can be detected, making it possible to measure not only normal force but also shear force; and (B) Using an insulating layer with a Poisson's ratio of 0 to 4.8 makes it easier to distinguish between pressure detection in the Z-axis direction and shear force detection in the X- and Y-axis directions. is stated.

[0008] Patent Document 3 states: a resin layer in which a second resin layer without a slit is formed on both sides of a first resin layer with a slit; a first electrode formed on one surface of the resin layer; a second electrode formed on the other surface of the resin layer; A shear force detecting unit including the above is disclosed.

[0009] The same document states: (A) When a slit is provided in the resin layer between the opposing electrodes, the detection unit becomes more likely to deform in the direction of the input force, and (B) This ensures the deformation performance of the resin layer even when the resin layer is thin. is stated.

[0010] Patent Document 4 discloses a tactile sensor in which an electrode layer, an X-direction dielectric layer that is anisotropic in deformation in the X direction, an electrode layer, a Y-direction dielectric layer that is anisotropic in deformation in the Y direction, an electrode layer, a Z-direction dielectric layer that is anisotropic in deformation in the Z direction, and an electrode layer are stacked in this order. The document describes that the use of such a tactile sensor makes it possible to resolve and detect an input load in three directions.

[0011] Non-Patent Document 1 discloses a flexible capacitance sensor in which finger-like electrodes are arranged on both sides of a dielectric body made of silicone rubber. The paper describes how finger-shaped electrodes can provide high sensitivity to forces in three directions while maintaining the flexibility of the sensor.

[0012] The force sensor described in Patent Document 1 is intended to detect only normal forces. In contrast, the sensors described in Patent Documents 2 to 4 and Non-Patent Document 1 are all capable of detecting not only normal forces but also shear forces. However, in the pressure sensor sheet described in Patent Document 2, the displacement in the shear force direction affects electrodes other than the electrodes for detecting capacitance changes, which may cause noise.

[0013] The sensors described in Patent Documents 3 and 4 make the resin layer (dielectric layer) more susceptible to shear deformation by providing slits in the resin layer. However, this method also makes the resin layer more susceptible to deformation in the vertical direction, so force component separation is required to measure the shear load. Therefore, it cannot be said that the significance of separating the detection unit into a vertical load detection unit and a shear load detection unit is utilized. Furthermore, the sensor described in Patent Document 4 has a structure in which three layers, namely, an X-direction dielectric layer, a Y-direction dielectric layer, and a Z-direction dielectric layer, are stacked together, which makes the sensor thick and makes it difficult to ensure sufficient flexibility.

[0014] Furthermore, the flexible capacitance sensor described in Non-Patent Document 1 detects forces in three axial directions only by optimizing the electrode shape. This may result in insufficient deformation in the shear direction, reducing the sensitivity of detecting shear loads. Furthermore, precise electrode formation is required. As described above, sensors that are flexible and capable of measuring forces in three axes have been known for some time. However, there have been no examples of shear force sensors that can suppress deformation in the compressive direction and emphasize deformation in the shear direction, nor of force sensor sheets and force sensors that use such sensors. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-203691 [Patent Document 2] Japanese Patent Application Publication No. 2020-046371 [Patent Document 3] Japanese Patent Publication No. 2020-148561 [Patent Document 4] Japanese Patent Application Laid-Open No. 2012-247297 [Non-patent literature]

[0016] [Non-Patent Document 1] Dobrzynska JA and Gijs MAM, "Polymer-based flexible capacitive sensor for three-axial force measurements," J. Micormech. Microeng., vol. 23, 015009(2013) Summary of the Invention [Problem to be solved by the invention]

[0017] An object of the present invention is to provide a shear force sensor that can suppress deformation in the compression direction and emphasize deformation in the shear direction. Another problem to be solved by the present invention is to provide a force sensor sheet and a force sensor that use such a shear force sensor. [Means for solving the problem]

[0018] In order to solve the above problems, the shear force sensor according to the present invention comprises: a dielectric layer A consisting of a laminate in which first to n-th soft layers (n≧2) and first to m-th hard layers (1≦m≦n−1, 1≦m≦n, or 1≦m≦n+1) are alternately laminated; a first electrode A bonded to one surface of the dielectric layer A; a second electrode A bonded to the other surface of the dielectric layer A; Equipped with The following formulas (1) to (3) are satisfied.

[0019] E soft,max <E hard,min …(1) ε soft,max <ε hard,min …(2) t soft,j >t hard,admin …(3) however, E soft,max is the maximum value of the elastic modulus of the first to nth soft layers, E hard,min is the minimum value of the elastic modulus of the first to mth hard layers, ε soft,max is the maximum value of the relative dielectric constant of the first to nth soft layers, ε hard,min is the minimum value of the relative dielectric constants of the first to mth hard layers, t soft,j is the thickness of the jth soft layer (1≦j≦n), t hard.adminis the minimum thickness of the kth hard layer (k is any one or two of j-1, j, or j+1) adjacent to the jth soft layer.

[0020] The force sensor sheet according to the present invention comprises: 1st to pth shear force sensors (p≧1) for measuring shear force; first to qth normal force sensors (q≧1) for measuring normal forces; a substrate for mounting the first to pth shear force sensors and the first to qth normal force sensors; Equipped with The first to pth shear force sensors each comprise a shear force sensor according to the present invention.

[0021] The force sensor according to the present invention comprises: a force sensor sheet according to the present invention; a measuring instrument for measuring changes in capacitance of the first to pth shear force sensors and the first to qth normal force sensors; It is equipped with: [Effects of the Invention]

[0022] The dielectric layer A, which is a laminate of two or more soft layers and one or more hard layers, is characterized by relatively small deformation in response to normal force and relatively large deformation in response to shear force. Therefore, by bonding electrodes to both sides of such a dielectric layer A, a shear force sensor is obtained that is low in sensitivity to normal force and high in sensitivity to shear force. Furthermore, by placing such a shear force sensor and a normal force sensor on the surface of a substrate, a force sensor sheet capable of detecting forces in three axial directions can be obtained. Furthermore, by combining such a force sensor sheet with a measuring device that measures changes in capacitance, a force sensor that can detect forces in three axial directions can be obtained. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a cross-sectional view of a shear force sensor according to the present invention; [Figure 2]FIG. 1 is a plan view of a force sensor sheet according to the present invention. [Figure 3] FIG. 1 is a schematic diagram illustrating the deformation behavior of a shear force sensor. DETAILED DESCRIPTION OF THE INVENTION

[0024] [Configuration 1] a dielectric layer A consisting of a laminate in which first to n-th soft layers (n≧2) and first to m-th hard layers (1≦m≦n−1, 1≦m≦n, or 1≦m≦n+1) are alternately laminated; a first electrode A bonded to one surface of the dielectric layer A; a second electrode A bonded to the other surface of the dielectric layer A; Equipped with Satisfy the following formulas (1) to (3): Shear force sensor. E soft,max <E hard,min …(1) ε soft,max <ε hard,min …(2) t soft,j >t hard,admin …(3)

[0025] however, E soft,max is the maximum value of the elastic modulus of the first to nth soft layers, E hard,min is the minimum value of the elastic modulus of the first to mth hard layers, ε soft,max is the maximum value of the relative dielectric constant of the first to nth soft layers, ε hard,min is the minimum value of the relative dielectric constants of the first to mth hard layers, t soft,j is the thickness of the jth soft layer (1≦j≦n), t hard.admin is the minimum thickness of the kth hard layer (k is any one or two of j-1, j, or j+1) adjacent to the jth soft layer.

[0026] [Configuration 2] The shear force sensor according to configuration 1, further satisfying the following formula (1.1) and / or formula (1.2): 0.01MPa≦E soft,j <100MPa …(1.1) E hard,k ≧100MPa …(1.2) however, E soft,j is the elastic modulus of the jth soft layer (1≦j≦n), E hard,k is the elastic modulus of the kth hard layer (1≦k≦m).

[0027] [Configuration 3] The shear force sensor according to configuration 1 or 2, further satisfying the following formula (2.1) and / or formula (2.2): ε soft,j ≧2.0 …(2.1) ε hard,k ≧4.0 …(2.2) however, ε soft,j is the relative dielectric constant of the jth soft layer (1≦j≦n), ε hard,k is the relative dielectric constant of the k hard layer (1≦k≦m).

[0028] [Configuration 4] A shear force sensor according to any one of configurations 1 to 3, further satisfying the following formula (3.1) and / or formula (3.2): 0.01mm≦t soft,j <3.0mm …(3.1) 0.003mm≦t hard,k <1.0mm …(3.2) however, t soft,j is the thickness of the jth soft layer (1≦j≦n), t hard,k is the thickness of the kth hard layer (1≦k≦m).

[0029] [Configuration 5] the first electrode A and the second electrode A are each composed of a rectangular electrode having the same dimensions, and are arranged so that their projection planes coincide when viewed from a normal direction of the dielectric layer A in an unloaded state; A shear force sensor according to any one of configurations 1 to 4, further satisfying the following formula (4): L1 / L2≧1.0 …(4) however, L1 is the length of the long side of the first electrode A (or the second electrode A), L2 is the length of the short side of the first electrode A (or the second electrode A).

[0030] [Configuration 6] the first electrode A and the second electrode A are each composed of a rectangular electrode having the same dimensions, and are arranged so that their projection planes coincide when viewed from a normal direction of the dielectric layer A in an unloaded state; A shear force sensor according to any one of configurations 1 to 5, further satisfying the following formula (5): X / Z≧5.0 …(5) however, X is 0.4 N / mm in the horizontal direction (the long side direction of the first electrode A or the long side direction of the second electrode A) and the vertical direction of the shear force sensor, respectively. 2 the horizontal displacement of the shear force sensor when the stresses of Z is 0.4 N / mm in the horizontal and vertical directions of the shear force sensor, respectively. 2 4. The vertical displacement of the shear force sensor when a stress of 1.0 V is applied simultaneously.

[0031] [Configuration 7] The first to nth soft layers each contain an elastomer A, Each of the first to mth hard layers contains at least one selected from the group consisting of elastomer B, a thermosetting resin, and a thermoplastic resin. 7. The shear force sensor of any one of configurations 1 to 6.

[0032] [Configuration 8] 8. The shear force sensor according to configuration 7, wherein at least one of the first to mth hard layers further contains an inorganic filler.

[0033] [Configuration 9] 1st to pth shear force sensors (p≧1) for measuring shear force; first to qth normal force sensors (q≧1) for measuring normal forces; a substrate for mounting the first to pth shear force sensors and the first to qth normal force sensors; Equipped with The first to pth shear force sensors each comprise a shear force sensor according to any one of configurations 1 to 8. Force sensor sheet.

[0034] [Configuration 10] Two or more of the first to pth shear force sensors are provided, At least two of the first to pth shear force sensors have anisotropy in their shear force detection sensitivity, and are placed on the substrate surface so that the directions in which the shear force detection sensitivity is maximized are non-parallel to each other. 10. The force sensor sheet according to configuration 9.

[0035] [Configuration 11] The first to qth normal force sensors each include: a dielectric layer B; a first electrode B bonded to one surface of the dielectric layer B; a second electrode B bonded to the other surface of the dielectric layer B; Equipped with The dielectric layer B satisfies the following formula (6): The force sensor sheet according to configuration 9 or 10.

[0036] E B <E hard,min …(6) however, E B is the elastic modulus of the dielectric layer B, E hard,min is the minimum value of the elastic modulus of the first to mth hard layers included in the first to pth shear force sensors.

[0037] [Configuration 12] A force sensor sheet according to any one of configurations 9 to 11, a measuring instrument for measuring changes in capacitance of the first to pth shear force sensors and the first to qth normal force sensors; A force sensor equipped with

[0038] [1. Shear force sensor] The shear force sensor according to the present invention comprises: a dielectric layer A consisting of a laminate in which first to n-th soft layers (n≧2) and first to m-th hard layers (1≦m≦n−1, 1≦m≦n, or 1≦m≦n+1) are alternately laminated; a first electrode A bonded to one surface of the dielectric layer A; a second electrode A bonded to the other surface of the dielectric layer A; It is equipped with:

[0039] [1.1. Dielectric Layer A] [1.1.1. Number of layers] The dielectric layer A is a laminate of two or more soft layers and one or more hard layers stacked alternately. In this case, the larger the number n of soft layers, the larger the amount of deformation in the shear direction. Therefore, n must be 2 or more. n is preferably 3 or more, 4 or more, or 5 or more.

[0040] On the other hand, even if n is made larger than necessary, there is no difference in the effect and it is of no practical benefit. Furthermore, depending on the thickness of the soft layer and the hard layer, if n is too large, the thickness of the dielectric layer A may become excessively thick, which may reduce the flexibility of the shear force sensor. Therefore, it is preferable to select an optimal value for n taking these points into consideration. The upper limit of n varies depending on the thickness of the soft layer and the hard layer, but it is preferably at most 20. n is preferably 15 or less, or 10 or less.

[0041] "Dielectric layer A where 1≦m≦n-1" refers to a laminate in which the total number of laminated soft layers and hard layers is an odd number (2n-1), and both end surfaces are made of soft layers. "Dielectric layer A where 1≦m≦n" refers to a laminate in which the total number of soft layers and hard layers is an even number (2n), and one end surface is made of a soft layer and the other end surface is made of a hard layer. "Dielectric layer A where 1≦m≦n+1" refers to a laminate in which the total number of laminated soft layers and hard layers is an odd number (2n+1), and both end surfaces are made of hard layers. The dielectric layer A according to the present invention may be any of the laminates described above.

[0042] In the present invention, when ordinal numbers are assigned to the soft and hard layers, the ordinal numbers are assigned to both the soft and hard layers in ascending order, starting from one end face of the dielectric layer A. For example, if the total number of layers is 2n-1, the ordinal numbers of each layer are defined as "first soft layer / first hard layer / second soft layer / second hard layer / ... / (n-1)th hard layer / nth soft layer."

[0043] [1.1.2. Soft layer, hard layer] In the present invention, the term "soft layer" refers to a layer made of a material having a lower modulus of elasticity than the hard layer. In the present invention, the "hard layer" refers to a layer made of a material having a higher elastic modulus than the soft layer. In the present invention, it is preferable that the first to nth soft layers and the first to mth hard layers each satisfy the following conditions.

[0044] [A. Elastic Modulus] The shear force sensor according to the present invention must satisfy the following formula (1). E soft,max <E hard,min …(1) however, E soft,max is the maximum value of the elastic modulus of the first to nth soft layers, E hard,min is the minimum value of the elastic modulus of the first to mth hard layers.

[0045] Formula (1) represents the elastic modulus condition that the soft layer and hard layer must satisfy. As long as formula (1) is satisfied, the first to nth soft layers may each be made of a material having the same elastic modulus, or may each be made of a material having a different elastic modulus. Similarly, as long as formula (1) is satisfied, the first to mth hard layers may each be made of a material having the same elastic modulus, or may each be made of a material having a different elastic modulus.

[0046] The shear force sensor according to the present invention preferably further satisfies the following formula (1.1) and / or formula (1.2). 0.01MPa≦E soft,j <100MPa …(1.1) E hard,k ≧100MPa …(1.2) however, E soft,j is the elastic modulus of the jth soft layer (1≦j≦n), E hard,k is the elastic modulus of the kth hard layer (1≦k≦m),

[0047] Equation (1.1) is the elastic modulus E of each jth soft layer (1≦j≦n) soft,j Generally, E soft,j The smaller the value, the larger the shear deformation. soft,j If E becomes too small, the soft layer may buckle, making it difficult to measure the capacitance accurately. soft,j are preferably 0.01 MPa or more. soft,j is more preferably 0.05 MPa or more, 0.10 MPa or more, or 0.20 MPa or more. On the other hand, E soft,j If E becomes too large, the deformation in the shear direction may become excessively small. soft,j are preferably less than 100 MPa. soft,j is more preferably 80 MPa or less, 60 MPa or less, 40 MPa or less, or 20 MPa or less.

[0048] Equation (1.2) is the elastic modulus E of each kth hard layer (1≦k≦m) hard,k Generally, E hard,k The larger the value, the smaller the deformation in the compression direction. hard,k are preferably 100 MPa or more. hard,k is more preferably 200 MPa or more, 300 MPa or more, 400 MPa or more, or 500 MPa or more. On the other hand, E hard,k If E becomes too large, the overall flexibility may decrease. hard,k is preferably 5000 MPa or less. hard,k is more preferably 2000 MPa or less, or 1000 MPa or less.

[0049] [B. Dielectric Constant] The shear force sensor according to the present invention must satisfy the following formula (2). ε soft,max <ε hard,min …(2) however, ε soft,max is the maximum value of the relative dielectric constant of the first to nth soft layers, ε hard,min is the minimum value of the relative dielectric constant of the first to mth hard layers.

[0050] Equation (2) represents the dielectric constant condition that the soft layer and hard layer must satisfy. As long as equation (2) is satisfied, the first to nth soft layers may be made of materials having the same dielectric constant, or may be made of materials having different dielectric constants. Similarly, as long as equation (2) is satisfied, the first to mth hard layers may be made of materials having the same dielectric constant, or may be made of materials having different dielectric constants.

[0051] The shear force sensor according to the present invention preferably further satisfies the following formula (2.1) and / or formula (2.2). ε soft,j ≧2.0 …(2.1) ε hard,k≧4.0 …(2.2) however, ε soft,j is the relative dielectric constant of the jth soft layer (1≦j≦n), ε hard,k is the relative dielectric constant of the k hard layer (1≦k≦m).

[0052] Equation (2.1) is the relative permittivity ε of each jth soft layer (1≦j≦n) soft,j Generally, ε soft,j The larger ε is, the larger the relative permittivity of the entire dielectric layer A becomes, and the higher the detection sensitivity of shear stress becomes. soft,j are preferably 2.0 or more. soft,j is more preferably 3.0 or more, 4.0 or more, or 5.0 or more. soft.j The bigger the better.

[0053] Equation (2.2) is the relative permittivity ε of each kth hard layer (1≦k≦m) hard,k Generally, ε hard,k The larger ε is, the larger the relative permittivity of the entire dielectric layer A becomes, and the higher the detection sensitivity of shear stress becomes. hard,k are preferably 4.0 or more. hard,k is more preferably 5.0 or more, 7.0 or more, or 10.0 or more. hard.k The bigger the better. Flexible materials generally have a low dielectric constant. On the other hand, adding a certain type of inorganic filler to a flexible material can improve the dielectric constant. Also, adding an inorganic filler usually improves the modulus of elasticity. Inorganic fillers will be described later.

[0054] [C. Thickness] The shear force sensor according to the present invention must satisfy the following formula (3). t soft,j >t hard,admin …(3) however, t soft,j is the thickness of the jth soft layer (1≦j≦n), t hard.adminis the minimum thickness of the kth hard layer (k is any one or two of j-1, j, or j+1) adjacent to the jth soft layer.

[0055] In addition, in formula (3), "k is one or two of j-1, j, or j+1" means that the ordinal number k of the hard layer adjacent to the soft layer formally changes depending on the position of the soft layer, the total number of soft and hard layers stacked, and the way the ordinal numbers are assigned.

[0056] For example, if the total number of layers is (2n-1), the dielectric layer A is made up of a laminate of "first soft layer / first hard layer / second soft layer / second hard layer / ... / (n-1)th hard layer / nth soft layer." In this case, the only hard layer adjacent to the first soft layer is the first hard layer (k=j). Also, the only hard layer adjacent to the nth soft layer is the (n-1)th hard layer (k=j-1). Furthermore, there are two hard layers adjacent to the second soft layer: the first hard layer (k=j-1) and the second hard layer (k=j).

[0057] On the other hand, when the total number of layers is (2n+1), the dielectric layer A is made up of a laminate of "first hard layer / first soft layer / second hard layer / ... / (n+1)th hard layer." In this case, the hard layers adjacent to the first soft layer are the first hard layer (k=j) and the second hard layer (k=j+1).

[0058] Formula (3) represents the thickness condition that the soft layer and hard layer must satisfy. As long as formula (3) is satisfied, the first to nth soft layers may each have the same thickness or different thicknesses. Similarly, as long as formula (3) is satisfied, the first to mth hard layers may each have the same thickness or different thicknesses.

[0059] In order to increase the amount of deformation in the shear direction, it is preferable that the shear force sensor satisfies the following formula (3'). t soft,j >t hard,admax …(3') however, t soft,jis the thickness of the jth soft layer (1≦j≦n), t hard.admax is the maximum value of the thickness of the kth hard layer (k is any one or two of j-1, j, or j+1) adjacent to the jth soft layer.

[0060] Equation (3') expresses that the thickness of each jth soft layer is greater than the maximum value of the thickness of the adjacent kth hard layer. Other points regarding equation (3') are the same as equation (3), so explanation will be omitted.

[0061] The shear force sensor according to the present invention preferably further satisfies the following formula (3.1) and / or formula (3.2). 0.01mm≦t soft,j <3.0mm …(3.1) 0.003mm≦t hard,k <1.0mm …(3.2) however, t soft,j is the thickness of the jth soft layer (1≦j≦n), t hard,k is the thickness of the kth hard layer (1≦k≦m).

[0062] Equation (3.1) is the thickness t of each jth soft layer (1≦j≦n) soft,j represents the preferred range of t soft,j If the thickness becomes too thin, the deformation in the shear direction may become small. soft,j It is preferable that each of these be 0.01 mm or more. soft,j is more preferably 0.03 mm or more, 0.05 mm or more, or 0.07 mm or more. On the other hand, t soft,j If t becomes too thick, the amount of deformation in the compression direction may increase, or the flexibility of the resin layer A may decrease. soft,j and are preferably less than 3.0 mm. soft,j is more preferably 2.0 mm or less, or 1.0 mm or less.

[0063] Equation (3.2) is the thickness t of each kth hard layer (1≦k≦m) hard,krepresents the preferred range of t hard,k If the thickness becomes too thin, it may be difficult to separate the shear and normal forces. hard,k is preferably 0.003 mm or more. hard,k is more preferably 0.005 mm or more, or 0.010 mm or more. On the other hand, t hard,k If the thickness is too large, the overall flexibility may decrease. hard,k is preferably less than 1.0 mm. hard,k is more preferably 0.8 mm or less, 0.6 mm or less, or 0.4 mm or less.

[0064] [D. Slit] The jth soft layer (1≦j≦n) and the kth hard layer (1≦k≦m) may each have a slit therein, or may not have a slit. However, if the jth soft layer (1≦j≦n) and / or the kth hard layer (1≦k≦m) have a slit, the amount of deformation in the compression direction may increase. Therefore, it is preferable that at least one of the jth soft layer (1≦j≦n) and / or the kth hard layer (1≦k≦m) does not have a slit. In order to suppress the amount of deformation in the compression direction, the more layers that do not have a slit, the better. In order to minimize the amount of deformation in the compression direction, it is preferable that the jth soft layer (1≦j≦n) and the kth hard layer (1≦k≦m) do not have a slit.

[0065] [E. Materials for the 1st to nth soft layers] The materials of the first to nth soft layers are not particularly limited as long as they satisfy the above-mentioned conditions. As long as they satisfy the above-mentioned conditions, the first to nth soft layers may be made of the same material or different materials. It is particularly preferable that the first to nth soft layers contain elastomer A. Elastomer A has a lower elastic modulus than other materials, and is therefore suitable as a material for the first to nth soft layers.

[0066] Examples of elastomer A include: Silicone elastomers, urethane elastomers, fluorine elastomers, Nitrile elastomers, butyl elastomers, styrene elastomers, Styrene butadiene elastomers, ethylene propylene elastomers, Ethylene propylene diene elastomers, olefin elastomers, Ester-based elastomers, vinyl chloride-based elastomers, and amide-based elastomers etc. Each jth soft layer (1≦j≦n) may be made of one of these materials, or may be made of two or more materials.

[0067] [F. Materials for the 1st to mth hard layers] [F.1. Main constituent materials] The materials of the first to mth hard layers are not particularly limited as long as they satisfy the above-mentioned conditions. As long as they satisfy the above-mentioned conditions, the first to mth hard layers may be made of the same material or different materials. The first to mth hard layers preferably contain at least one selected from the group consisting of elastomer B, a thermosetting resin, and a thermoplastic resin.

[0068] Examples of elastomer B include: Silicone elastomers, urethane elastomers, fluorine elastomers, Nitrile elastomers, butyl elastomers, styrene elastomers, Styrene butadiene elastomers, ethylene propylene elastomers, Ethylene propylene diene elastomers, olefin elastomers, Ester-based elastomers, vinyl chloride-based elastomers, and amide-based elastomers, etc.

[0069] Examples of thermosetting resins include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, acrylonitrile butadiene styrene resin, acrylic resin, polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polyester, cyclic polyolefin, polyphenylene sulfide, polytetrafluoroethylene, polyvinylidene fluoride, polysulfone, polyethersulfone, liquid crystal polymer, polyetheretherketone, thermoplastic polyimide, and polyamideimide. Examples of thermoplastic resins include epoxy resins, phenolic resins, melamine resins, urea resins, unsaturated polyester resins, silicone resins, and thermosetting polyimides. Each kth hard layer (1≦k≦m) may be made of one of these materials, or may be made of two or more of these materials.

[0070] [F.2. Inorganic Fillers] At least one of the first to mth hard layers may further contain an inorganic filler. Organic materials such as elastomer B, thermosetting resin, or thermoplastic resin generally have a low modulus of elasticity and a low dielectric constant. In contrast, adding an inorganic filler to an organic material improves the modulus of elasticity. Furthermore, when the inorganic filler is a high-dielectric-constant material, adding the inorganic filler to the organic material improves not only the modulus of elasticity but also the dielectric constant.

[0071] The material of the inorganic filler is not particularly limited, and an optimum material can be selected depending on the purpose. Examples of the material of the inorganic filler include: (a) Composition formula: A1 2+ B1 4+ Perovskite compounds represented by O3 (b) Composition formula: A2 1+ B2 5+ Ilmenite compounds represented by O3, or (c) a solid solution or mixture containing at least two compounds selected from the group consisting of the perovskite compound and the ilmenite compound; All of these have a relatively large dielectric constant.

[0072] however, A1 is Ba, Sr, Ca, (Na 0.5 Bi 0.5 ), and (K 0.5 Bi 0.5 ) at least one selected from the group consisting of B1 is at least one selected from the group consisting of Ti, Zr, and Hf; A2 is at least one selected from the group consisting of Li, Na, K, and Ag; B2 is at least one selected from the group consisting of Nb, Ta, and Sb.

[0073] When the kth hard layer contains an inorganic filler, the content thereof is not particularly limited, and an optimum content can be selected depending on the purpose. Here, the "content of inorganic filler" refers to the ratio of the mass of the inorganic filler contained in the k-th hard layer to the total mass of the k-th hard layer.

[0074] Generally, the higher the content of the inorganic filler, the higher the elastic modulus or the dielectric constant of the k-th hard layer. To achieve such effects, the content of the inorganic filler is preferably 2 mass% or more. The content is more preferably 5 mass% or more, or 10 mass% or more. On the other hand, if the content of the inorganic filler is excessive, the flexibility of the dielectric layer A may be excessively reduced. Therefore, the content of the inorganic filler is preferably 70 mass% or less. The content is more preferably 60 mass% or less, or 50 mass% or less.

[0075] [1.2. 1st electrode A, 2nd electrode A] A first electrode A is bonded to one surface of the dielectric layer A. A second electrode A is bonded to the other surface of the dielectric layer A.

[0076] [1.2.1. Shape] In the present invention, the shapes of the first electrode A and the second electrode A are not particularly limited as long as they can detect shear force with high sensitivity. Examples of the shapes of the first electrode A and the second electrode A include square, rectangle, circle, ellipse, diamond, and lens shapes.

[0077] As long as shear force can be detected with high sensitivity, the shape of the first electrode A may be the same as or different from that of the second electrode A. Furthermore, as long as shear force can be detected with high sensitivity, the position of the center of gravity of the first electrode A in the no-load state may coincide with or be shifted from that of the second electrode A. Furthermore, when the first electrode A and the second electrode A have the same shape, they may be arranged so that their projection surfaces completely coincide with each other in the no-load state, or so that their projection surfaces do not coincide with each other. Optimizing the shape and / or arrangement of the first electrode A and the second electrode B produces anisotropy in the detection sensitivity of shear force. Therefore, by using two or more shear force sensors arranged so that the directions of high detection sensitivity are non-parallel, it is possible to measure not only the magnitude of the shear force but also the direction of the shear force.

[0078] When the first electrode A and the second electrode A are each composed of a rectangular electrode having the same dimensions and are arranged so that their projection planes coincide when viewed from the normal direction of the dielectric layer A in an unloaded state, It is preferable that the shear force sensor further satisfies the following formula (4) in addition to the above formulas (1) to (3). L1 / L2≧1.0 …(4) however, L1 is the length of the long side of the first electrode A (or the second electrode A), L2 is the length of the short side of the first electrode A (or the second electrode A).

[0079] Here, "having the same dimensions" means that the dimensional error of the long side and the dimensional error of the short side are each 5% or less. The "dimensional error of the long side" refers to the ratio of the absolute value of the difference in the length of the long side, |a1-a2|, to the average length (a1+a2) / 2 of the long side a1 of the first electrode A and the long side a2 of the second electrode A. The "dimensional error of the short side" refers to the ratio of the absolute value of the difference in the short side lengths |b1-b2| to the average length (b1+b2) / 2 of the short side b1 of the first electrode A and the short side b2 of the second electrode A. When the first electrode A or the second electrode A is square, the "length of the long side (or short side)" refers to the length of one side.

[0080] "The projection surfaces coincide" means that the positional deviation between the first electrode A and the second electrode B is 5% or less. "Positional deviation" refers to the average value S of the area S1 of the first electrode A and the area S2 of the second electrode A. m =(S1+S2) / 2, S m and the area of ​​the overlapping region S p Absolute value of the difference between |S m -S p | refers to the percentage of "The area of ​​the overlapping region S p " refers to the area of ​​the region where the projection plane of the first electrode A and the projection plane of the second electrode A overlap when viewed from the normal direction of the dielectric layer A in an unloaded state.

[0081] Equation (4) indicates that even if there is some dimensional error or positional misalignment in the first electrode A and / or the second electrode A, it is sufficient that the L1 / L2 ratio of at least one of the first electrode A or the second electrode A satisfies the condition of equation (4). Generally, the larger the L1 / L2 ratio, the greater the shear stress detection sensitivity. Also, the larger the L1 / L2 ratio, the greater the anisotropy of the detection sensitivity. To achieve this effect, the L1 / L2 ratio is preferably 1.0 or greater. The L1 / L2 ratio is more preferably 1.1 or greater, 1.2 or greater, 1.3 or greater, 1.4 or greater, or 1.5 or greater. The larger the L1 / L2 ratio, the better.

[0082] [1.2.2. Materials] In the present invention, the materials of the first electrode A and the second electrode A are not particularly limited, and an optimum material can be selected depending on the purpose. Examples of materials for the first electrode A and the second electrode A include Pt, Au, Ag, Cu, and C. Alternatively, the first electrode A and the second electrode A may be made of rubber or polymer with the above-mentioned conductive substances dispersed therein.

[0083] 1.3. Characteristics: Maximum X / Z Displacement Ratio When the first electrode A and the second electrode A are each composed of a rectangular electrode having the same dimensions and are arranged so that their projection planes coincide when viewed from the normal direction of the dielectric layer A in an unloaded state, It is preferable that the shear force sensor further satisfies the following formula (5) in addition to the above formulas (1) to (4). X / Z≧5.0 …(5) however, X is 0.4 N / mm in the horizontal direction (the long side direction of the first electrode A or the long side direction of the second electrode A) and the vertical direction of the shear force sensor, respectively. 2 the horizontal displacement of the shear force sensor when the stresses of Z is 0.4 N / mm in the horizontal and vertical directions of the shear force sensor, respectively. 2 4. The vertical displacement of the shear force sensor when a stress of 1.0 V is applied simultaneously.

[0084] Equation (5) indicates that even if there is some dimensional error or positional deviation in the first electrode A and / or the second electrode A, it is sufficient if the X / Z ratio satisfies the condition of equation (5) when a predetermined stress is applied in either the long side direction of the first electrode A or the long side direction of the second electrode A. In the shear force sensor according to the present invention, the dielectric layer A is composed of a laminate of a soft layer and a hard layer, so it is possible to suppress deformation in the compression direction and emphasize deformation in the shear direction. By optimizing the shape and materials of each part, the X / Z ratio can be 5.0 or greater. By further optimizing the shape and materials of each part, the X / Z ratio can be 6.0 or greater, 7.0 or greater, 8.0 or greater, 9.0 or greater, or 10.0 or greater.

[0085] [1.4. Specific Examples] FIG. 1 shows a cross-sectional schematic diagram of a shear force sensor according to a first embodiment of the present invention. In FIG. 1, the shear force sensor 10 includes a dielectric layer A20, a first electrode A32, and a second electrode A34. The dielectric layer A20 is a laminated body in which a first hard layer 22a, a first soft layer 24a, a second hard layer 22b, a second soft layer 24b, and a third hard layer 22c are laminated in this order. In other words, the dielectric layer A20 is a laminated body with a five-layer structure.

[0086] The first electrode A32 is bonded to the lower surface of the dielectric layer A20. The second electrode A34 is bonded to the upper surface of the dielectric layer A20. The first electrode A32 and the second electrode A34 have the same shape. The first electrode A32 and the second electrode A34A are bonded to the dielectric layer A so that their projection planes completely coincide when viewed from the normal direction of the dielectric layer A20. Other aspects regarding the materials and shapes of the dielectric layer A20, the first electrode A32, and the second electrode A34 are as described above, and therefore will not be described again.

[0087] [2. Force sensor sheet] The force sensor sheet according to the present invention comprises: 1st to pth shear force sensors (p≧1) for measuring shear force; first to qth normal force sensors (q≧1) for measuring normal forces; a substrate for mounting the first to pth shear force sensors and the first to qth normal force sensors; It is equipped with:

[0088] [2.1. 1st to pth shear force sensors] The first to pth shear force sensors are for measuring shear force. Each of the first to pth shear force sensors is a shear force sensor according to the present invention. Details of the shear force sensors are as described above, so further explanation will be omitted.

[0089] The number of the first to pth shear force sensors may be one, or may be two or more. When the force sensor sheet includes two or more 1st to pth shear force sensors, it is preferable that at least two of the 1st to pth shear force sensors have anisotropy in their detection sensitivity to shear force, and that the sensors are placed on the substrate surface so that the directions in which the shear force detection sensitivity is greatest are non-parallel to each other. By arranging two or more shear force sensors with anisotropy in detection sensitivity so that their high-sensitivity directions are non-parallel, it is possible to measure not only the magnitude of the shear force but also the direction of the shear force.

[0090] [2.2. 1st to qth normal force sensors] The first to qth normal force sensors are for measuring normal forces. There are no particular limitations on the first to qth normal force sensors as long as they are capable of measuring normal forces.

[0091] The first to qth normal force sensors are respectively: a dielectric layer B; a first electrode B bonded to one surface of the dielectric layer B; a second electrode B bonded to the other surface of the dielectric layer B; It is preferable that the device has the following.

[0092] Furthermore, it is preferable that the dielectric layer B satisfies the following formula (6). E B <E hard,min …(6) however, E B is the elastic modulus of the dielectric layer B, E hard,min is the minimum value of the elastic modulus of the first to mth hard layers included in the first to pth shear force sensors.

[0093] The first to qth normal force sensors are used in a state where they are arranged on the same plane as the first to pth shear force sensors. B is the minimum value E of the elastic modulus of the 1st to mth hard layers. hard,min If E is larger than 1 / 2, the detection sensitivity of the normal force of the first to qth normal force sensors may be lower than that of the first to pth shear force sensors. B is E hard,minLess than E is preferred. B More preferably, the maximum value E of the elastic modulus of the first to nth soft layers included in the first to pth shear force sensors soft,max The following is the result.

[0094] The shape and material of the first electrode B and the second electrode B are not particularly limited as long as they are capable of detecting a normal force. The number of the first to qth normal force sensors may be 1, or may be 2 or more. The number of the first to qth normal force sensors is preferably selected optimally depending on the size of the force sensor sheet. Furthermore, when multiple first to qth normal force sensors are placed on the substrate surface, it is preferable to select the optimal placement location depending on the purpose.

[0095] 2.3. Substrate The substrate is for mounting the first to pth shear force sensors and the first to qth normal force sensors on its surface. In the present invention, the shape of the substrate and the arrangement of the sensors on the substrate are not particularly limited, and an optimum shape can be selected depending on the purpose. In the present invention, the material of the substrate is not particularly limited, and an optimum material can be selected depending on the purpose. The substrate may be made of a flexible or inflexible material. In order to enable the force sensor sheet to be placed on a curved surface, the substrate is preferably made of a flexible material. Examples of substrate materials include insulating rubber sheets made of the various elastomers described above, and insulating polymer films made of the various thermoplastic or thermosetting resins described above.

[0096] [2.4. Specific Examples] 2 shows a plan view of a force sensor sheet according to the present invention. In FIG. 2, a force sensor sheet 40 includes a first shear force sensor 10a, a second shear force sensor 10b, a normal force sensor 50, and a substrate 60.

[0097] The first shear force sensor 10a and the second shear force sensor 10b each have a rectangular planar shape. The first shear force sensor 10a is placed on the lower left of the substrate 60 with its long side parallel to the y-axis direction. On the other hand, the second shear force sensor 10b is placed on the upper right of the substrate 60 with its long side parallel to the x-axis direction. Furthermore, the normal force sensor 50 is placed on the lower right of the substrate 60.

[0098] A first electrode terminal 72a and a second electrode terminal 74a for extracting output are respectively joined to the upper and lower electrodes of the first shear force sensor 10a. Similarly, a first electrode terminal 72b and a second electrode terminal 74b for extracting output are respectively joined to the upper and lower electrodes of the second shear force sensor 10b. Similarly, a first electrode terminal 72c and an electrode terminal 74c for extracting output are respectively joined to the uppermost electrode of the normal force sensor 50.

[0099] When an external force acts from any direction on the surface of the force sensor sheet shown in Figure 2, the dielectric layers included in the first shear force sensor 10a, the second shear force sensor 10b, and the normal force sensor 50 deform, causing a change in dielectric constant. In this case, the shear force component and its direction of the external force can be determined from the outputs of the first shear force sensor 10a and the second shear force sensor 10b. In addition, the magnitude of the normal force component of the external force can be determined from the output of the normal force sensor 50.

[0100] [3. Force Sensor] The force sensor according to the present invention comprises: a force sensor sheet according to the present invention; a measuring instrument for measuring changes in capacitance of the first to pth shear force sensors and the first to qth normal force sensors; It is equipped with:

[0101] [3.1. Force sensor sheet] Details of the force sensor sheet have been described above, and therefore will not be described here.

[0102] 3.2. Measuring Instruments The measuring instrument is used to measure the changes in capacitance of the first to pth shear force sensors and the first to qth normal force sensors included in the force sensor sheet. Examples of measuring instruments that make up the force sensor include an LCR meter, an impedance analyzer, or a measurement circuit consisting of a microcomputer (e.g., Arduino, Raspberry Pi, etc.) and various passive elements.

[0103] [4. Effect] Most commercially available sheet-type force sensors can only measure normal forces. Therefore, there is a demand for flexible force sensors that can measure not only normal forces but also shear forces. There are various types of force sensors known that use different force detection methods. One of these is the capacitance-type force sensor, which uses the change in capacitance of a dielectric layer caused by deformation that occurs when force is applied to the dielectric layer.

[0104] Since there is a correlation between load and capacitance, if this relationship is known in advance, it is possible to measure force. The capacitance C can be calculated using the following equation (7). C=ε0ε r S / d …(7) however, ε0 is the dielectric constant of a vacuum (8.854×10 -12 F / m), ε r is the relative permittivity of the dielectric layer, S is the area of ​​the opposing electrodes, d is the thickness of the dielectric layer.

[0105] As can be seen from equation (7), when the relative permittivity of the dielectric layer is high, the electrode area is large, and the thickness of the dielectric layer is small, the capacitance C exhibits a large value. A large capacitance C means that the sensor has high resolution, which is advantageous in terms of force detection. In many cases, force acts on an object three-dimensionally, so when a force acts on a single sensor, deformation due to the force in all three directions is reflected in the change in capacitance. However, it is usually not possible to measure forces in three directions with a single sensor.

[0106] For this reason, sensors have been proposed that measure forces in three axial directions by performing calculations based on the difference in capacitance detection values ​​of two or more sensor elements in different positions. However, although elastomers and resins are flexible, their relative dielectric constant is usually low, at 5 or less. Therefore, the change in capacitance during deformation is very small. In particular, since the force acting in the shear direction is often smaller than that acting in the compression direction, the change in capacitance is very small, making it difficult to measure accurately.

[0107] In contrast, a dielectric layer A consisting of a laminate of two or more soft layers and one or more hard layers is characterized by relatively small deformation in response to normal force and relatively large deformation in response to shear force. Therefore, by bonding electrodes to both sides of such a dielectric layer A, a shear force sensor with low sensitivity to normal force and high sensitivity to shear force can be obtained. Furthermore, by placing such a shear force sensor and a normal force sensor on the surface of a substrate, a force sensor sheet capable of detecting forces in three axial directions can be obtained. Furthermore, by combining such a force sensor sheet with a measuring device that measures changes in capacitance, a force sensor that can detect forces in three axial directions can be obtained.

[0108] Figure 3 shows a schematic diagram of the deformation behavior of a shear force sensor. The dotted line box indicates the overlapping area of ​​the opposing electrodes. Below, we will explain how structural differences in a single sensor element affect the deformation behavior and capacitance associated with the application of force. As shown in the upper part of Figure 3, when a single material with a low elastic modulus is used as the dielectric layer, the dielectric layer can deform not only when only a normal load is applied but also when only a shear load is applied, and when both a normal load and a shear load are applied simultaneously, the dielectric layer can deform in both the normal and shear directions.

[0109] When a normal load is applied, the capacitance increases due to the decrease in the thickness of the dielectric layer. On the other hand, when a shear load is applied, the upper and lower electrodes are displaced, which reduces the effective component of the capacitance, i.e., the electrode area, resulting in a decrease in capacitance. Furthermore, when a normal load and a shear load are applied simultaneously, the capacitance exhibits a combination of the above effects.

[0110] In contrast, if the dielectric layer has a laminated structure of a soft layer with a low elastic modulus and a hard layer with a high elastic modulus, as shown in the bottom of Figure 3, even if a vertical load is applied to the dielectric layer, the vertical deformation of the dielectric layer is small because it is constrained by the hard layer. On the other hand, because it is not constrained in the shear direction, the flexible soft layer deforms, allowing the dielectric layer to deform in the shear direction. Furthermore, when a vertical load and a shear load are applied to the dielectric layer simultaneously, the dielectric layer deforms almost only in the vertical direction and only in the shear direction.

[0111] By utilizing these differences in deformation behavior, it is possible to detect forces in the three axial directions separately. In other words, a single flexible material can be used for the dielectric layer of the sensor to detect normal force. With a sheet-type sensor, it is easy to make the electrode area larger compared to the sensor thickness. In this case, the effect of normal force is dominant, so normal force can be extracted. On the other hand, by using a laminate of soft and hard layers for the dielectric layer of the sensor to detect shear force, it is possible to effectively extract the effect of shear load while suppressing the effect of normal load. By measuring the change in capacitance, the shear load can be calculated.

[0112] If the modulus of elasticity of the hard layer is high, the entire laminate will also be hard, but by reducing the thickness of the hard layer, it is possible to provide a certain degree of flexibility. Furthermore, when using elastomer or resin alone as the hard layer, it is generally difficult to obtain a hard layer with a high dielectric constant. However, by adding inorganic filler to the elastomer or resin, it is relatively easy to achieve a high dielectric constant. Furthermore, the addition of inorganic filler also has the effect of increasing the elastic modulus.

[0113] In the shear force sensor according to the present invention, when the dielectric layer is made of an organic material, the thickness can be reduced and the shear force sensor can be made flexible. Furthermore, by forming the dielectric layer of the shear force sensor into a laminated structure made of multiple materials with different physical properties, shear force can be detected effectively. Furthermore, since the dielectric layer includes a layer with a high relative dielectric constant, a large change in capacitance can be obtained in response to deformation.

[0114] Therefore, by using a force sensor equipped with the shear force sensor according to the present invention, it is possible to accurately measure triaxial forces acting on a part with a flat or curved contact surface. As a result, for example, by attaching the sensor to a person's limbs, it is possible to measure in detail the triaxial forces acting during work. Furthermore, because the sensor is thin, it allows for greater design freedom when attaching it to equipment such as robots, contributing to the enhancement of equipment functionality. [Example]

[0115] (Examples 1 to 5, Comparative Examples 1 and 2) [1. Test Method] Using computer-aided engineering (CAE), we confirmed the horizontal displacement, vertical displacement, and capacitance change when vertical and shear loads were applied to sensors with various structures. FEMTET (Murata Soft Air Co., Ltd.) was used for the calculations. In this study, we assumed a single sensor element with a rectangular parallelepiped shape. We calculated the capacitance taking into account the deformation that occurs when a specified force is applied to the sensor element, and compared it with the capacitance before the application. The common calculation conditions are as follows:

[0116] The depth of the model was 5 mm. The total thickness of the soft layer was 0.9 mm. Load: 0.4N / mm 2 It was decided. A normal load, a shear load, or both a normal load and a shear load were applied to the sensor element through a rigid body placed on the entire upper surface of the sensor element. - The deformation of the entire lower surface of the sensor element was constrained. The potential difference between both ends of the sensor element was set to 1V. Each material that makes up the sensor element is assumed to undergo elastic deformation. Each element that makes up the model is a hexahedral element.

[0117] [2. Results] The calculation results are shown in Table 1. Note that "maximum displacement" refers to the displacement of the node that was displaced the most by the application of load, shown for each axis. Also, "maximum displacement rate" refers to the maximum displacement, shown for each axis, as a ratio to the total length or thickness before the application of load. From Table 1, the following can be seen.

[0118] (1) Comparative Example 1 is an example in which the dielectric layer is composed of a single soft layer. Because the elastic modulus of the dielectric layer in Comparative Example 1 is low, it was able to deform under both normal and shear loads. Furthermore, the capacitance of Comparative Example 1 when both normal and shear loads were applied was close to that when only normal load was applied. This indicates that Comparative Example 1 is not suitable as a shear force sensor. On the other hand, Comparative Example 1 can be said to be suitable as a normal force sensor. Furthermore, Comparative Example 1 has flexibility due to the low elastic modulus of the dielectric layer. The reason for the displacement in the X-axis direction in response to the normal load is that it stretches laterally when compressed.

[0119] (2) Comparative Example 2 is an example in which the dielectric layer is a laminate with a two-layer structure including one soft layer and one hard layer. Comparative Example 2 exhibited performance almost equivalent to that of Comparative Example 1. This indicates that Comparative Example 2 is suitable as a normal force sensor, but not as a shear force sensor.

[0120] (3) Examples 1 to 4 are examples in which the dielectric layer includes two or more soft layers and is composed of a laminate with three or more layers. As the number of hard layers increases, the amount of deformation in the vertical direction tends to decrease. As a result, the capacitance change with respect to the vertical load becomes smaller as the number of hard layers increases. On the other hand, even if the number of hard layers was increased, the amount of shear deformation was almost unchanged. As a result, the capacitance when normal force and shear force were applied simultaneously was almost the same as that when shear force alone was applied. Although the total thickness of the soft layers and the total thickness of the hard layers were the same in Examples 1 to 4 and Comparative Example 2, the effects were significantly different.

[0121] (4) Example 5 is an example in which the L1 / L2 ratio is increased. In Example 5, it was confirmed that the same effects as in Examples 1 to 4 were achieved. (5) From the above, it was confirmed that it was possible to extract capacitance changes due to shear force while maintaining flexibility in Examples 1 to 5. Therefore, it was found that by using a sensor for detecting normal force in which the dielectric layer is made of a single flexible material and has an isotropic planar shape, and by using a sensor for detecting shear force in which the dielectric layer has a laminated structure and has a rectangular planar shape, it becomes easier to separate forces in the three axial directions, enabling force measurement with high accuracy.

[0122] [Table 1]

[0123] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention. [Industrial Applicability]

[0124] The force sensor according to the present invention can be used as a sensor for measuring the force acting on an object during human movement or robot work.

Claims

1. a dielectric layer A consisting of a laminate in which first to n-th soft layers (n≧2) and first to m-th hard layers (1≦m≦n−1, 1≦m≦n, or 1≦m≦n+1) are alternately stacked; a first electrode A bonded to one surface of the dielectric layer A; a second electrode A bonded to the other surface of the dielectric layer A; Equipped with Satisfy the following formulas (1) to (3): Shear force sensor. E soft,max <E hard,min …(1) e soft,max <e hard,min …(2) t soft,j >t hard,admin …(3) however, E soft,max is the maximum value of the elastic modulus of the first to nth soft layers, E hard,min is the minimum value of the elastic modulus of the first to mth hard layers, ε soft,max is the maximum value of the relative dielectric constant of the first to nth soft layers, ε hard,min is the minimum value of the relative dielectric constants of the first to mth hard layers, t soft,j is the thickness of the jth soft layer (1≦j≦n), t hard.admin is the minimum thickness of the kth hard layer (k is any one or two of j-1, j, or j+1) adjacent to the jth soft layer.

2. The shear force sensor according to claim 1 , further satisfying the following formula (1.1) and / or formula (1.2): 0.01MPa≦E soft,j <100MPa …(1.1) E hard,k ≧100MPa …(1.2) however, E soft,j is the elastic modulus of the jth soft layer (1≦j≦n), E hard,k is the elastic modulus of the kth hard layer (1≦k≦m).

3. The shear force sensor according to claim 1 , further satisfying the following formula (2.1) and / or formula (2.2): e soft,j ≧2.0 …(2.1) e hard,k ≧4.0 …(2.2) however, ε soft,j is the relative dielectric constant of the jth soft layer (1≦j≦n), ε hard,k is the relative dielectric constant of the kth hard layer (1≦k≦m).

4. The shear force sensor according to claim 1 , further satisfying the following formula (3.1) and / or formula (3.2): 0.01mm≦t soft,j <3.0mm …(3.1) 0.003mm≦t hard,k <1.0mm …(3.2) however, t soft,j is the thickness of the jth soft layer (1≦j≦n), t hard,k is the thickness of the kth hard layer (1≦k≦m).

5. the first electrode A and the second electrode A are each composed of a rectangular electrode having the same dimensions, and are arranged so that their projection planes coincide when viewed from a normal direction of the dielectric layer A in an unloaded state; The shear force sensor according to claim 1 , further satisfying the following formula (4): L 1 / L 2 ≧1.0 …(4) however, L 1 is the length of the long side of the first electrode A (or the second electrode A), L 2 is the length of the short side of the first electrode A (or the second electrode A).

6. the first electrode A and the second electrode A are each composed of a rectangular electrode having the same dimensions, and are arranged so that their projection planes coincide when viewed from a normal direction of the dielectric layer A in an unloaded state; The shear force sensor according to claim 1 , further satisfying the following formula (5): X / Z≧5.0…(5) however, X is 0.4 N / mm in the horizontal direction (the long side direction of the first electrode A or the long side direction of the second electrode A) and the vertical direction of the shear force sensor. 2 the horizontal displacement of the shear force sensor when the stresses of Z is 0.4 N / mm in the horizontal and vertical directions of the shear force sensor, respectively. 2 4. The vertical displacement of the shear force sensor when a stress of 1.0 V is applied simultaneously.

7. first to pth shear force sensors (p≧1) for measuring shear force; first to qth normal force sensors (q≧1) for measuring normal forces; a substrate for mounting the first to pth shear force sensors and the first to qth normal force sensors; Equipped with The first to p-th shear force sensors are each a shear force sensor according to claim 1. Force sensor sheet.

8. Two or more of the first to pth shear force sensors are provided, At least two of the first to pth shear force sensors have anisotropy in their shear force detection sensitivity, and are placed on the substrate surface such that the directions in which the shear force detection sensitivity is maximized are non-parallel to each other. The force sensor sheet according to claim 7 .

9. The first to qth normal force sensors each include: a dielectric layer B; a first electrode B bonded to one surface of the dielectric layer B; a second electrode B bonded to the other surface of the dielectric layer B; Equipped with The dielectric layer B satisfies the following formula (6): The force sensor sheet according to claim 7 . E B <E hard,min …(6) however, E B is the elastic modulus of the dielectric layer B, E hard,min is the minimum value of the elastic modulus of the first to mth hard layers included in the first to pth shear force sensors.

10. The force sensor sheet according to claim 7; a measuring instrument for measuring changes in capacitance of the first to pth shear force sensors and the first to qth normal force sensors; A force sensor equipped with

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