Force sensor

Abstract

To provide a three-axis force sensor capable of suppressing an increase in the number of electrodes and wiring.SOLUTION: A force sensor 10 includes a dielectric elastic substrate 11, and a first electrode 13 and three second electrodes 15 sandwiching the elastic substrate 11 from both sides in the thickness direction thereof. In a plan view along the thickness direction, the three second electrodes 15 are arranged so as to overlap different portions of the first electrode 13. When an external force acts on the elastic substrate 11 along each of a first direction and a second direction that form a predetermined angle on a plane perpendicular to the predetermined direction, an area corresponding to at least any two of the second electrodes 15 changes among the areas of the portions where each of the three second electrodes 15 overlaps with the first electrode 13.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a force sensor. [Background technology]

[0002] Conventionally, a flexible capacitive three-axis force sensor has been known that includes four first electrodes (peripheral electrodes) and one second electrode (common electrode) that sandwich an elastically deformable dielectric body from both sides in the thickness direction (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-111489 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, in the case of a sensor device mounted in a location where layout space is limited, such as a robot hand, it is desirable to reduce the number of electrodes and wiring. For example, a large number of electrodes and wiring can lead to a problem of making it difficult to achieve a space-saving layout. For example, a large number of wirings can lead to a problem of making it difficult to increase the S / N ratio of the sensor due to increased crosstalk between the wirings. For example, a large number of electrodes per sensor element constituting a sensor array can lead to a problem of increased processing time due to the increased number of times the capacitance value of each electrode is measured. For example, a large number of flexible wirings can lead to a problem of increased likelihood of abnormalities occurring due to weak bonding strength in the circuit.

[0005] An object of the present invention is to provide a force sensor that can suppress an increase in the number of electrodes and wirings. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the above object, the present invention employs the following aspects. (1): A force sensor according to one aspect of the present invention (e.g., force sensors 10, 10A, 10B, 10C, 10D, 10E, and 10F in the embodiments) includes a dielectric elastic substrate (e.g., elastic substrate 11 and 51 in the embodiments), a first electrode (e.g., first electrodes 13, 61A, 61B, and 61C in the embodiments) and three second electrodes (e.g., second electrodes 15, 63, and 65 in the embodiments) sandwiching the elastic substrate from both sides in a predetermined direction. In a plan view along the predetermined direction, the three second electrodes are arranged to overlap different portions of the first electrode. When an external force acts on the elastic substrate along each of a first direction and a second direction that form a predetermined angle on a plane perpendicular to the predetermined direction, the area of ​​the overlapping portion between each of the three second electrodes and the first electrode, which corresponds to at least any two of the second electrodes, changes.

[0007] (2): A force sensor according to one aspect of the present invention (e.g., force sensors 30, 30A, and 30B in the embodiments) comprises a dielectric elastic substrate (e.g., elastic substrate 11 and 51 in the embodiments), and a plurality of electrode elements (e.g., electrode elements E and Ea, first electrode element E1, and second electrode element E2 in the embodiments) that are integrally arranged, each of the electrode elements being a combination of a first electrode (e.g., first electrode 13 and 61C in the embodiments) and three second electrodes (e.g., second electrode 15 and 65 in the embodiments) that sandwich the elastic substrate from both sides in a predetermined direction. In a plan view seen along the predetermined direction, the three second electrodes in each of the plurality of electrode elements are arranged so as to overlap different portions of the first electrode, and the three second electrodes in each of the plurality of electrode elements are arranged along three different straight lines (e.g., second straight lines in the embodiments) that are parallel to one another.

[0008] (3): The force sensor described in (1) or (2) above may include a processing unit (e.g., processing unit 20 in the embodiment) that sets a correction coefficient (e.g., correction coefficients ηa, ηb in the embodiment) for the capacitance (e.g., capacitances Ca, Cb in the embodiment) of one of the three second electrodes as a reference for the other two second electrodes in accordance with the area of ​​the portion where each of the three second electrodes overlaps with the first electrode (e.g., areas Sa0, Sb0, Sc0 before displacement, and areas Sa, Sb, Sc after displacement in the embodiment), and acquires the external force acting on the elastic substrate based on the correction coefficient and the capacitance (e.g., capacitances Ca, Cb, Cc in the embodiment) of each of the three second electrodes. [Effects of the Invention]

[0009] According to (1) above, by combining a first electrode with three second electrodes, the action of a three-dimensional external force can be detected by a change in capacitance, and an increase in the number of electrodes and wiring can be suppressed compared to, for example, when four or more second electrodes are provided.

[0010] According to (2) above, in the multiple electrode elements, each of the three second electrodes is arranged in a straight line parallel to one another, thereby suppressing an increase in crosstalk between wiring lines compared to, for example, when the three second electrodes are arranged along straight lines that intersect with one another.

[0011] In the case of (3) above, even if the areas of the portions overlapping with the first electrode differ among the three second electrodes, by providing a processing unit that sets a capacitance correction coefficient based on one of the electrodes as a reference, it is possible to properly detect capacitance changes caused by the action of a three-dimensional external force. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a configuration diagram of a force sensor according to an embodiment of the present invention, viewed along the thickness direction (Z-axis direction). [Figure 2]2 is a cross-sectional view showing the force sensor according to the embodiment of the present invention, taken along a plane (YZ plane) parallel to the thickness direction (Z-axis direction) at the position of line AA shown in FIG. 1. [Figure 3] FIG. 2 is a diagram showing a state in which an external force acting along the Y-axis direction is applied to the force sensor according to the embodiment of the present invention, as viewed along the thickness direction (Z-axis direction). [Figure 4] FIG. 2 is a configuration diagram of an array-type force sensor according to an embodiment of the present invention, viewed along the thickness direction (Z-axis direction). [Figure 5] FIG. 4 is a cross-sectional view showing a force sensor according to a first modified example of the embodiment of the present invention, taken along the YZ plane. [Figure 6] FIG. 10 is a cross-sectional view showing a force sensor according to a second modified example of the embodiment of the present invention, taken along the YZ plane. [Figure 7] FIG. 10 is a configuration diagram of an array-type force sensor according to a third modified example of the embodiment of the present invention, viewed along the thickness direction (Z-axis direction). [Figure 8] FIG. 10 is a configuration diagram of a force sensor according to a fourth modified example of the embodiment of the present invention, viewed along the thickness direction (Z-axis direction). [Figure 9] FIG. 11 is a configuration diagram of a force sensor according to a fifth modified example of the embodiment of the present invention, viewed along the thickness direction (Z-axis direction). [Figure 10] FIG. 13 is a configuration diagram of a force sensor according to a sixth modified example of the embodiment of the present invention, viewed along the thickness direction (Z-axis direction). [Figure 11] FIG. 13 is a configuration diagram of a force sensor according to a seventh modified example of the embodiment of the present invention, viewed along the thickness direction (Z-axis direction). [Figure 12] FIG. 13 is a configuration diagram of an array-type force sensor according to a seventh modified example of the embodiment of the present invention, viewed along the thickness direction (Z-axis direction). [Figure 13] FIG. 13 is a cross-sectional view showing a part of an array-type force sensor according to a seventh modified example of the embodiment of the present invention, cut along the XY plane. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a force sensor according to an embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a configuration diagram of a force sensor 10 according to an embodiment as viewed along the thickness direction (Z-axis direction). Fig. 2 is a cross-sectional view of the force sensor 10 according to the embodiment, taken along line AA in Fig. 1 and cut along a plane (YZ plane) parallel to the thickness direction (Z-axis direction). In the following description, the X-axis, Y-axis, and Z-axis directions, which are perpendicular to each other in three-dimensional space, are parallel to each other. For example, as shown in Figures 1 and 2, the Z-axis direction is parallel to the thickness direction of the force sensor 10, and the X-axis and Y-axis directions are parallel to the directions perpendicular to the thickness direction.

[0014] The force sensor 10 of the embodiment is, for example, a flexible and stretchable circuit device that is attached to or worn by a human body or a robot. The force sensor 10 of the embodiment is, for example, a flexible capacitance-type three-axis force sensor. As shown in Figures 1 and 2, the force sensor 10 includes, for example, a dielectric elastic substrate 11, a first electrode 13, three second electrodes 15 (15a, 15b, 15c), a first conducting wire 17, three second conducting wires 19a, 19b, 19c, and a processing unit 20. The dielectric elastic substrate 11 is, for example, a flexible dielectric material such as a so-called thermosetting elastomer.

[0015] The first electrode 13 and the three second electrodes 15 are formed of a flexible and stretchable conductive material, such as a resin containing a conductive metal filler. The first electrode 31 has an outer shape of, for example, a rectangular plate. The three second electrodes 15 each have an outer shape of, for example, a rectangular plate of the same size but smaller than the first electrode 13. The first electrode 13 and the three second electrodes 15 constitute one electrode element E. The first electrode 13 and the three second electrodes 15 are arranged inside the elastic substrate 11 facing each other at a predetermined interval in the thickness direction, for example, so as to sandwich a part of the elastic substrate 11 from both sides in the thickness direction (Z-axis direction).

[0016] For example, the three second electrodes 15a, 15b, and 15c are arranged so as to overlap different portions of the first electrode 13 in a plan view along the thickness direction. Of the three second electrodes 15a, 15b, and 15c, two second electrodes 15a and 15c are arranged so as to overlap two predetermined adjacent corners of the four corners of the first electrode 13. Of the three second electrodes 15a, 15b, and 15c, the remaining second electrode 15b is arranged so as to overlap a portion between two corners other than the two predetermined adjacent corners of the four corners of the first electrode 13. For example, in a state where no external force is applied, the areas of two of the three second electrodes 15a, 15b, and 15c overlapping with the first electrode 13 are the same. The total area of ​​the areas where the two second electrodes 15a and 15c overlap with the first electrode 13 is the same as the area of ​​the area where the remaining second electrode 15b overlaps with the first electrode 13.

[0017] The first conductive wire 17 and the three second conductive wires 19a, 19b, and 19c are each formed of a flexible and stretchable conductive material, such as a resin containing a conductive metal filler. The first conductive wire 17 connects the first electrode 13 to the processing unit 20. The three second conductive wires 19a, 19b, and 19c connect the three second electrodes 15a, 15b, and 15c to the processing unit 20. The three second conductive wires 19a, 19b, and 19c are arranged, for example, in the same plane (XY plane) perpendicular to the thickness direction, in parallel without intersecting each other. For example, in a plan view seen along the thickness direction, first conducting wire 17 and each of the three second conducting wires 19a, 19b, and 19c are arranged along a first line and a second line that intersect at a predetermined angle. First conducting wire 17 is arranged parallel to the first line, and each of the three second conducting wires 19a, 19b, and 19c is arranged parallel to the second line. The first and second lines are, for example, the X-axis and Y-axis, which are orthogonal to each other.

[0018] The processing unit 20 is a software functional unit that functions when a processor such as a CPU (Central Processing Unit) executes a predetermined program. The software functional unit is an ECU that includes a processor such as a CPU, a ROM (Read Only Memory) that stores programs, a RAM (Random Access Memory) that temporarily stores data, and electronic circuits such as a timer. At least a part of the processing unit 20 may be an integrated circuit such as an LSI (Large Scale Integration).

[0019] For example, the processing unit 20 regards a combination of one first electrode 13 and three second electrodes 15a, 15b, and 15c as one electrode element E, and transmits and receives input and output signals for detecting capacitance between each electrode element E via the first conducting wire 17 and three second conducting wires 19a, 19b, and 19c. The processing unit 20 acquires the capacitance of each electrode element E based on the input and output signals for each electrode element E. The processing unit 20 detects changes in capacitance due to deformation of the elastic substrate 11 between the first electrode 13 and the three second electrodes 15a, 15b, and 15c caused by the application of an external force. Based on the changes in capacitance, the processing unit 20 detects the magnitude and distribution of the external force acting on each electrode element in three axial directions (X-axis, Y-axis, and Z-axis directions that are orthogonal to each other).

[0020] For example, as shown in Table 1 below, the capacitances C1, C2, and C3 between the first electrode 13 and each of the three second electrodes 15a, 15b, and 15c change depending on the direction in which the external force acts.

[0021] [Table 1]

[0022] In the example shown in Table 1 above, when an external force acts on the elastic substrate 11 along each of the perpendicular X-axis and Y-axis directions on the XY plane perpendicular to the thickness direction (Z-axis direction), the area corresponding to at least any two of the areas where each of the three second electrodes 15 (15a, 15b, 15c) overlaps with the first electrode 13 changes.

[0023] FIG. 3 is a view of the force sensor 10 of the embodiment when viewed in the thickness direction (Z-axis direction) in a state where an external force along the Y-axis direction is applied to the force sensor 10. In the example shown in FIG. 3, when an external force F acts along the Y-axis direction, the first electrode 13 is displaced relatively in the positive direction of the Y-axis with respect to the three second electrodes 15a, 15b, and 15c. For example, in a planar view along the thickness direction, the area changes ΔSa, ΔSb, ΔSb of the portions where the first electrode 13 and each of the three second electrodes 15a, 15b, 15c overlap are expressed as shown in the following formula (1) using the areas Sa0, Sb0, Sc0 before displacement and the areas Sa, Sb, Sc after displacement.

[0024]

number

[0025] The capacitances Ca, Cb, and Cc between the first electrode 13 and each of the three second electrodes 15a, 15b, and 15c after displacement are expressed as shown in the following equation (2) using the dielectric constant ε of the elastic substrate 11, the areas Sa, Sb, and Sc after displacement, and the distance d in the thickness direction between the first electrode 13 and each of the three second electrodes 15a, 15b, and 15c after displacement.

[0026]

number

[0027] For example, the processing unit 20 sets capacitance correction coefficients for the other two of the three second electrodes 15a, 15b, and 15c, using one of the three second electrodes 15a, 15b, and 15c as a reference, based on the area changes ΔSa, ΔSb, and ΔSb and the areas Sa, Sb, and Sc after the displacement. For example, the correction coefficients ηa and ηb set for the two second electrodes 15a and 15b, using second electrode 15c as a reference, are expressed as shown in the following equation (3). Note that the correction coefficient ηc for the reference second electrode 15c is 1.

[0028]

number

[0029] The processing unit 20 multiplies each of the capacitances Ca, Cb, and Cc by each of the correction coefficients ηa, ηb, and ηc (=1) based on, for example, the above formulas (2) and (3) to obtain each of the corrected capacitances (ηa×Ca), (ηb×Cb), and (ηc(=1)×Cc). The processing unit 20 obtains the external force F acting on the elastic substrate 11 based on each of the corrected capacitances (ηa×Ca), (ηb×Cb), and (ηc×Cc).

[0030] FIG. 4 is a configuration diagram of the array-type force sensor 30 according to the embodiment, viewed along the thickness direction (Z-axis direction). As shown in FIG. 4, the array-type force sensor 30 includes, for example, a dielectric elastic substrate 11, a plurality of electrode elements E arranged integrally, a plurality of first conductive wires 17, a plurality of sets of second conductive wires 19a, 19b, 19c, and a processing unit 20 (not shown).

[0031] For example, in a plan view seen along the thickness direction, the plurality of electrode elements E are arranged in a plurality of rows parallel to the Y axis direction at predetermined intervals in the X axis direction. The plurality of first electrodes 13 and the plurality of second electrodes 15 (15a, 15b, 15c) are arranged, for example, in a staggered pattern. The multiple first electrodes 13 are arranged along the X-axis direction, for example, with a predetermined gap between them in each of multiple rows along the X-axis direction. The multiple first electrodes 13 are arranged, for example, with a predetermined gap between them in each of multiple rows parallel to the Y-axis direction, with a predetermined gap between them in the X-axis direction. The multiple first electrodes 13 arranged in a staggered pattern in each of the multiple rows aligned in the Y-axis direction are connected by, for example, first conducting wires 17 that are alternately inclined in opposite directions in the Y-axis direction with respect to the X-axis direction.

[0032] The multiple sets of three second electrodes 15a, 15b, and 15c are arranged, for example, in multiple rows parallel to the Y-axis direction and spaced apart at predetermined intervals in the X-axis direction. The multiple second electrodes 15 are arranged in a so-called square staggered (45-degree staggered) pattern so that, for example, if the centers of adjacent second electrodes 15 are connected by a line segment, a right-angled isosceles triangle is formed. For example, in each of the multiple rows arranged in the X-axis direction, the multiple second electrodes 15a are connected by second conducting wires 19a parallel to the Y-axis direction, the multiple second electrodes 15b are connected by second conducting wires 19b parallel to the Y-axis direction, and the multiple second electrodes 15c are connected by second conducting wires 19c parallel to the Y-axis direction.

[0033] In the case of an array-type force sensor 30, for example, the processing unit 20 sequentially switches between selecting one of the multiple electrode elements E and connecting it to the connected state. The processing unit 20 sequentially switches between a combination of one first conducting wire 17 and one set of second conducting wires 19a, 19b, 19c to be connected from among the multiple first conducting wires 17 and multiple sets of second conducting wires 19a, 19b, 19c. The processing unit 20 sets all the electrodes other than the one first conducting wire 17 and the set of second conducting wires 19a, 19b, 19c to be connected to a reference potential by grounding or the like. The processing unit 20 transmits and receives input signals and output signals for detecting capacitance to and from each electrode element E to be connected.

[0034] As described above, according to the force sensor 10 of the embodiment, by combining one first electrode 13 and three second electrodes 15, the action of a three-dimensional external force can be detected by a change in capacitance, and an increase in the number of electrodes and wiring can be suppressed compared to, for example, when four or more second electrodes are provided. For example, by suppressing an increase in the number of electrodes and wires, it is possible to suppress the difficulty of space-saving layout in locations where layout space is limited, such as robot hands. For example, by suppressing an increase in the number of wires, it is possible to suppress an increase in crosstalk between wires and a decrease in the S / N ratio of the force sensor 10. For example, by suppressing an increase in the number of electrodes, it is possible to suppress an increase in the number of times the capacitance value of each second electrode 15 is measured, thereby suppressing an increase in processing time. For example, by suppressing an increase in the number of flexible wires, it is possible to suppress an increase in the possibility of abnormalities occurring due to low bonding strength in the circuit.

[0035] According to the array-type force sensor 30 of the embodiment, in the multiple electrode elements E, each of the three second electrodes 15 (15a, 15b, 15c) is arranged in a straight line parallel to one another, thereby suppressing an increase in crosstalk between wiring lines compared to, for example, when the three second electrodes 15 are arranged along straight lines that intersect with one another.

[0036] Even if the areas of the portions overlapping with the first electrode 13 differ among the three second electrodes 15 (15a, 15b, 15c), by providing a processing unit 20 that sets correction coefficients ηa, ηb, ηc for each capacitance Ca, Cb, Cc based on one of the electrodes as a reference, it is possible to properly detect changes in capacitance caused by the action of a three-dimensional external force.

[0037] (Variation) Modifications of the embodiment will be described below. Note that the same parts as those in the above-described embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted or simplified. In the above-described embodiment, the three second conducting wires 19a, 19b, and 19c are arranged on the same plane (XY plane), but this is not limiting. For example, the three second conducting wires 19a, 19b, and 19c may be arranged on different planes that are perpendicular to the thickness direction. FIG. 5 is a cross-sectional view showing a force sensor 10A according to a first modified example of the embodiment, cut along the YZ plane, similar to FIG. 2 described above. As shown in FIG. 5, a force sensor 10A according to the first modified example includes, for example, a first conductor layer 41, a second conductor layer 43, a first dielectric layer 45, and a second dielectric layer 47 in addition to the components of the force sensor 10 according to the above-described embodiment.

[0038] The force sensor 10A according to the first modified example is formed into a multilayer structure, for example, by an elastic substrate 11, a first conductor layer 41, a first dielectric layer 45, a second conductor layer 43, and a second dielectric layer 47, which are stacked in sequence in the thickness direction. Each of the first conductor layer 41 and the second conductor layer 43 is made of a flexible and stretchable conductive material, such as a resin containing a conductive metal filler. The first conductor layer 41 and the second conductor layer 43 are set to a reference potential by, for example, grounding. Like the elastic substrate 11, each of the first dielectric layer 45 and the second dielectric layer 47 is made of a flexible dielectric material such as a so-called thermosetting elastomer.

[0039] For example, two second conducting wires 19a, 19c extend from two second electrodes 15a, 15c in the elastic substrate 11 along the thickness direction, penetrating the first conductor layer 41 and disposed within the first dielectric layer 45. One second conducting wire 19b extends from one second electrode 15b in the elastic substrate 11 along the thickness direction, sequentially penetrating the first conductor layer 41, the first dielectric layer 45, and the second conductor layer 43, and disposed within the second dielectric layer 47. According to the first variant, shielding can be formed between each second electrode 15a, 15b, 15c and each second conducting wire 19a, 19b, 19c, as well as between the three second conducting wires 19a, 19b, 19c, thereby increasing the S / N ratio of the force sensor 10A.

[0040] In the above-described embodiment, the three second electrodes 15 (15a, 15b, 15c) are arranged inside the elastic base material 11, but this is not limiting. For example, the three second electrodes 15 may be supported on an insulating substrate or the like. FIG. 6 is a cross-sectional view showing a force sensor 10B according to a second modified example of the embodiment, taken along the YZ plane, similar to FIG. 2 described above. As shown in FIG. 6, the force sensor 10B according to the second modification is formed into a multilayer structure, for example, by an elastic substrate 51, a first insulating layer 53, a conductor layer 55, and a second insulating layer 57, which are stacked in order in the thickness direction.

[0041] The dielectric elastic substrate 51 is, for example, a flexible dielectric material such as a so-called thermosetting elastomer, etc. The elastic substrate 51 supports, for example, the first electrode 13 disposed therein. The first insulating layer 53 and the second insulating layer 57 are, for example, flexible and stretchable insulators such as so-called flexible substrates. The first insulating layer 53 supports, for example, three second electrodes 15a, 15b, and 15c that are exposed from the surface and in contact with the elastic base material 51. The conductor layer 55 is made of a flexible and stretchable conductive material such as a resin containing a conductive metal filler, etc. The conductor layer 55 is set to a reference potential by, for example, grounding.

[0042] For example, the three second conductive wires 19a, 19b, and 19c extend from the three second electrodes 15a, 15b, and 15c in the first insulating layer 53 through the conductor layer 55 in the thickness direction and are disposed in the second insulating layer 57. According to the second variant, shielding can be formed between each second electrode 15a, 15b, 15c and each second conducting wire 19a, 19b, 19c, and shielding can be formed between the three second conducting wires 19a, 19b, 19c, while suppressing an increase in the thickness dimension, thereby increasing the S / N ratio of the force sensor 10B.

[0043] In the above-described embodiment, the array-type force sensor 30 includes a plurality of first electrodes 13 arranged in a staggered manner in accordance with a plurality of electrode elements E arranged in a staggered manner in a plan view along the thickness direction, but is not limited to this. For example, the plurality of first electrodes 13 may be arranged in a matrix of orthogonal rows and columns in a plan view along the thickness direction. FIG. 7 is a configuration diagram of an array-type force sensor 30A according to a third modified example of the embodiment, viewed along the thickness direction (Z-axis direction) in the same manner as in FIG. 4 described above.

[0044] A force sensor 30A according to the third modification includes, for example, a plurality of first electrode elements E1 and a plurality of second electrode elements E2 instead of the plurality of electrode elements E in the force sensor 30 of the above-described embodiment. Each of the first electrode element E1 and the second electrode element E2 includes a first electrode 13 and three second electrodes 15 (15a, 15b, 15c). The first electrode element E1 and the second electrode element E2 include, for example, three second electrodes 15a, 15b, 15c arranged relative to the first electrode 13 so as to be symmetrical about the X-axis in a plan view seen along the thickness direction. For example, the first electrode element E1 is the same as the electrode element E of the above-described embodiment.

[0045] For example, in a planar view along the thickness direction, a plurality of first electrode elements E1 and a plurality of second electrode elements E2 are arranged in alternating rows parallel to the Y axis direction at a predetermined interval in the X axis direction. The multiple first electrodes 13 are arranged, for example, in a matrix at predetermined intervals in each of the X-axis direction and the Y-axis direction. The multiple first electrodes 13 arranged in series in the X-axis direction in each of the multiple columns arranged in the Y-axis direction are connected, for example, by first conducting wires 17 parallel to the X-axis direction.

[0046] The multiple sets of three second electrodes 15a, 15b, and 15c are arranged, for example, in multiple rows parallel to the Y-axis direction and spaced apart at predetermined intervals in the X-axis direction. The multiple second electrodes 15 are arranged in a so-called square staggered (45-degree staggered) pattern so that, for example, if the centers of adjacent second electrodes 15 are connected by a line segment, a right-angled isosceles triangle is formed. For example, in each of the multiple rows arranged in the X-axis direction, the multiple second electrodes 15a are connected by second conducting wires 19a parallel to the Y-axis direction, the multiple second electrodes 15b are connected by second conducting wires 19b parallel to the Y-axis direction, and the multiple second electrodes 15c are connected by second conducting wires 19c parallel to the Y-axis direction. According to the third modification, it is possible to prevent each first conducting wire 17 from becoming longer than in the above-described embodiment.

[0047] In the above-described embodiment, the outer shape of each of the first electrode 31 and the second electrode 15 is a rectangular plate, but this is not limiting and the electrode may be a plate having a shape other than a rectangle. Fig. 8 is a configuration diagram of a force sensor 10C according to a fourth modified example of the embodiment, viewed along the thickness direction (Z-axis direction). Fig. 9 is a configuration diagram of a force sensor 10D according to a fifth modified example of the embodiment, viewed along the thickness direction (Z-axis direction). Fig. 10 is a configuration diagram of a force sensor 10E according to a sixth modified example of the embodiment, viewed along the thickness direction (Z-axis direction). Fig. 11 is a configuration diagram of a force sensor 10F according to a seventh modified example of the embodiment, viewed along the thickness direction (Z-axis direction).

[0048] 8, the outer shape of a first electrode 61A of a force sensor 10C according to the fourth modification is a right-angled triangular plate. In a plan view seen along the thickness direction when no external force is applied, three second electrodes 15a, 15b, and 15c are arranged to overlap different portions (for example, three vertices) of the first electrode 61A.

[0049] 9, the first electrode 61B of the force sensor 10D according to the fifth modification has an outer shape of an elliptical plate, and the three second electrodes 63 (63a, 63b, 63c) have outer shapes of circular plates. In a plan view seen along the thickness direction when no external force is applied, the three second electrodes 63a, 63b, 63c are arranged so as to overlap with different portions of the first electrode 61B (for example, both ends of the major axis and one end of the minor axis).

[0050] In the force sensor 10C according to the fourth modified example and the force sensor 10D according to the fifth modified example, the three second electrodes 15, 63 are arranged so that a right-angled isosceles triangle is formed when the centers of adjacent second electrodes 15 or adjacent second electrodes 63 are connected by a line segment.

[0051] 10, the first electrode 61C of the force sensor 10E according to the sixth modification has an outer shape of a regular hexagonal plate, and the three second electrodes 63 (63a, 63b, 63c) have outer shapes of circular plates. In a plan view along the thickness direction when no external force is applied, the three second electrodes 63a, 63b, 63c are arranged so as to overlap different portions (e.g., three sides) of the first electrode 61C. The areas and shapes of the regions where the three second electrodes 63a, 63b, 63c overlap the first electrode 61C are the same.

[0052] 11, the outer shape of a first electrode 61C of a force sensor 10E according to the seventh modification is a regular hexagonal plate, and the outer shapes of three second electrodes 65 (65a, 65b, 65c) are also regular hexagonal plate shapes. In a plan view along the thickness direction when no external force is applied, the three second electrodes 65a, 65b, 65c are arranged so as to overlap different portions (e.g., three sides) of the first electrode 61C. The areas and shapes of the regions where the three second electrodes 65a, 65b, 65c overlap the first electrode 61C are identical.

[0053] In the force sensor 10E according to the sixth modified example and the force sensor 10F according to the seventh modified example, the three second electrodes 63, 65 are arranged at a so-called 120° phase so that an equilateral triangle is formed when the centers of adjacent second electrodes 63 or adjacent second electrodes 65 are connected by a line segment. In the force sensor 10E according to the sixth modified example and the force sensor 10F according to the seventh modified example, in a plan view along the thickness direction, the area and shape of the region where each second electrode 63 or each second electrode 65 overlaps with the first electrode 61C are the same, and therefore, the correction coefficients ηa, ηb, and ηc for each capacitance Ca, Cb, and Cc as in the above-described embodiment are 1.

[0054] FIG. 12 is a configuration diagram of an array-type force sensor 30B according to a seventh modification of the embodiment, viewed along the thickness direction (Z-axis direction). 12, an array-type force sensor 30B according to the seventh modification includes, for example, a plurality of electrode elements Ea. The plurality of electrode elements Ea are arranged in a so-called 60-degree staggered pattern so that, for example, an equilateral triangle is formed when the centers of adjacent electrode elements Ea are connected by a line segment. Each electrode element Ea includes a first electrode 61C and three second electrodes 65 (65a, 65b, 65c). The plurality of first electrodes 61C and the plurality of second electrodes 65 are each arranged in a so-called 60-degree staggered pattern.

[0055] For example, the multiple first electrodes 61C are connected by multiple first conducting wires 17 parallel to the X-axis (first straight line). The multiple second electrodes 65a are connected by second conducting wires 19a parallel to the second straight line, the multiple second electrodes 65b are connected by second conducting wires 19b parallel to the second straight line, and the multiple second electrodes 65c are connected by second conducting wires 19c parallel to the second straight line. The first straight line and the second straight line intersect at an angle of 60 degrees, for example. According to the seventh variant, multiple electrode elements Ea can be arranged at a higher density than in the above-mentioned embodiment and the third variant, and it is possible to prevent the difficulty of space-saving layout in areas where layout space is limited, such as a robot hand.

[0056] FIG. 13 is a cross-sectional view showing a part of an array-type force sensor 30B according to a seventh modified example of the embodiment, cut along the XY plane. As shown in FIG. 13, an array-type force sensor 30B according to the seventh modification may include, in addition to a multilayer structure in the thickness direction, like the force sensor 10B according to the second modification shown in FIG. 6, multiple conductor layers 71 that shield each of three adjacent second conductive wires 19a, 19b, and 19c in the same plane (XY plane). Each of the multiple conductor layers 71 is formed of a flexible and stretchable conductive material, such as a resin containing a conductive metal filler. Each conductor layer 71 is set to a reference potential, for example, by grounding. The multiple conductor layers 71 are arranged, for example, to sandwich each of the three second conductive wires 19a, 19b, and 19c from both sides in the X-axis direction. According to the seventh variant, shielding can be formed between each second electrode 65a, 65b, 65c and each second conducting wire 19a, 19b, 19c, as well as between the three second conducting wires 19a, 19b, 19c, thereby increasing the S / N ratio of the force sensor 30B.

[0057] In the above-described embodiment, at least one of the shape and size of each of the three second electrodes 15 (15a, 15b, 15c) does not have to be the same as each other, and may be, for example, different shapes or sizes. In the above-described embodiment, for example, when viewed in a plane along the thickness direction, the plurality of electrode elements E, the plurality of electrode elements E1, E2, or the plurality of electrode elements Ea may be arranged in an appropriate regular manner, such as an appropriate staggered arrangement, an arrangement along orthogonal or oblique rows and columns, an arrangement along the circumference of concentric circles, or an arrangement along an appropriate figure, etc.

[0058] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0059] 10, 10A, 10B, 10C, 10D, 10E, 10F...force sensor, 11...elastic substrate, 13...first electrode, 15, 15a, 15b, 15c...second electrode, 17...first conducting wire, 19a, 19b, 19c...second conducting wire, 20...processing section, 30, 30A, 30B...force sensor, 41...first conducting layer, 43...second conducting layer, 45...first dielectric layer, 47...second dielectric layer, 51...elastic substrate, 53...first insulating layer, 55...conductor layer, 57...second insulating layer, 61A, 61B, 61C...first electrode, 63, 63a, 63b, 63c...second electrode, 65, 65a, 65b, 65c...second electrode, 71...conductor layer.

Claims

1. a dielectric elastic substrate; A first electrode and three second electrodes sandwiching the elastic base material from both sides in a predetermined direction; Equipped with In a plan view along the predetermined direction, the three second electrodes are arranged to overlap different portions of the first electrode, When an external force acts on the elastic base material along each of a first direction and a second direction that form a predetermined angle on a plane perpendicular to the predetermined direction, the area corresponding to at least any two of the second electrodes among the areas of the portions where each of the three second electrodes and the first electrode overlap changes. Force sensor.

2. a dielectric elastic substrate; A combination of a first electrode and three second electrodes sandwiching the elastic base material from both sides in a predetermined direction is regarded as one electrode element, and a plurality of the electrode elements are integrally arranged. Equipped with In a plan view along the predetermined direction, In each of the plurality of electrode elements, the three second electrodes are arranged to overlap different portions of the first electrode, Each of the three second electrodes in the plurality of electrode elements is arranged along three different straight lines parallel to each other. Force sensor.

3. a capacitance correction coefficient is set for each of the three second electrodes based on one of the three second electrodes in accordance with an area of ​​an overlap between the three second electrodes and the first electrode; a processing unit that acquires an external force acting on the elastic base material based on the correction coefficient and the electrostatic capacitance of each of the three second electrodes. The force sensor according to claim 1 or 2.

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