Force sensor

Abstract

To provide a force sensor that can be reduced in size.SOLUTION: A strain generating body according to the present invention includes: a first connection structure part that is connected to a first sensor body; a second connection structure part that is connected to the first sensor body; and a third connection structure part that connects the first connection structure body and second connection structure body to a second sensor body. A detection element includes: a stationary electrode substrate that is provided on the second sensor body; and a displacement electrode substrate that is displaced with the second connection structure part. When seen in a first direction, the strain generating bodies are arranged at different positions in a circumferential direction with respect to the center of the first sensor body. The strain generating bodies are arranged so that a second direction extends along a direction toward the outside from the center of the first sensor body.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] There is a known force sensor that outputs the force acting in a specific axial direction and the moment (or torque) acting around a specific rotation axis as an electrical signal. Force sensors are widely used for force control of various robots, including industrial robots, collaborative robots, life support robots, medical robots, and service robots. The market size of force sensors is expanding due to the widespread use of robots.

[0003] The force sensor is placed between the robot arm and the end effector (or gripper, etc.) and detects the force acting on the workpiece. The detected force is used to control the robot. For example, if the robot arm comes into contact with a person, the force sensor detects the contact. This makes it possible to bring the operation of the robot arm to an emergency halt.

[0004] As described above, since the force sensor is disposed between the robot arm and the end effector, there is a demand for the force sensor to be miniaturized. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-135103 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above points, and has an object to provide a force sensor that can be made smaller. [Means for solving the problem]

[0007] [1] This disclosure: a first sensor body that receives the force or moment to be detected; a second sensor body disposed at a position different from the first sensor body in a first direction; a plurality of strain bodies that connect the first sensor body and the second sensor body and are elastically deformed by the action of a force or moment applied to the first sensor body; a detection element that detects a change in capacitance value based on a displacement caused by elastic deformation of the strain body; a detection circuit that outputs an electrical signal indicative of a force or moment acting on the first sensor body based on a detection result of the detection element; Equipped with the strain body includes a first connection structure connected to the first sensor body, a second connection structure connected to the first sensor body, the second connection structure being arranged at a position different from the first connection structure in a second direction perpendicular to the first direction, and a third connection structure connecting the first connection structure and the second connection structure to the second sensor body, the third connection structure being arranged between the first connection structure and the second connection structure in the second direction, the detection element includes a fixed electrode substrate provided on the second sensor body, and a displacement electrode substrate opposed to the fixed electrode substrate and displaced together with the second connection structure, When viewed in the first direction, each of the strain bodies is disposed at a different position in a circumferential direction with respect to a center of the first sensor body, The strain generating body is disposed so that the second direction is along a direction from the center of the first sensor body toward the outside. It may be a force sensor.

[0008] [2] This disclosure: The displacement electrode substrate includes a one-side displacement electrode substrate arranged on one side with respect to a central axis of the strain body, and an other-side displacement electrode substrate arranged on the other side with respect to the central axis in a third direction perpendicular to each of the first direction and the second direction. The force sensor may be as described in [1].

[0009] [3] This disclosure: When viewed in the first direction, the second connection structure of each of the strain bodies is disposed at a position closer to the center of the first sensor body than the corresponding first connection structure. The force sensor may be as described in [1] or [2].

[0010] [4] This disclosure: When viewed in the first direction, the second direction of each of the strain bodies is radially disposed with respect to the center of the first sensor body. The force sensor may be any one of those described in [1] to [3].

[0011] [5] This disclosure: The first sensor body and the second sensor body are connected by four of the strain bodies. The force sensor may be any one of those described in [1] to [4].

[0012] [6] This disclosure: the second connection structure portion includes a 21st connection portion extending from the first sensor body toward the second sensor body and a 22nd connection portion connecting the third connection structure portion and the 21st connection portion, the one-side displacement electrode substrate and the other-side displacement electrode substrate are connected to a surface of the 21st connection portion facing the second sensor body; The force sensor may be any one of those described in [1] to [5].

[0013] [7] This disclosure: the strain body includes a displacement portion connected to a surface of the second connection structure portion facing the second sensor body, the one-side displacement electrode substrate and the other-side displacement electrode substrate are connected to a surface of the displacement portion facing the second sensor body; The force sensor may be any one of those described in [1] to [6].

[0014] [8] This disclosure: the first connection structure portion includes an eleventh connection portion extending from the first sensor body toward the second sensor body and a twelfth connection portion connecting the third connection structure portion and the eleventh connection portion, the second connection structure portion includes a 21st connection portion extending from the first sensor body toward the second sensor body and a 22nd connection portion connecting the third connection structure portion and the 21st connection portion, the eleventh connection portion and the twenty-first connection portion extend in the first direction, The 12th connection portion and the 22nd connection portion extend in the second direction. The force sensor may be any one of those described in [1] to [7].

[0015] [9] This disclosure: a distance in the second direction between the one-side displacement electrode substrate and the central axis of the strain body is greater than a distance in the third direction between the one-side displacement electrode substrate and the central axis of the strain body; The force sensor may be any one of those described in [1] to [8].

[0016]

[10] This disclosure relates to: The spring constant of the second connection structure is smaller than the spring constant of the first connection structure. The force sensor may be any one of those described in [1] to [9].

[0017]

[11] This disclosure relates to: the one-side displacement electrode substrate and the other-side displacement electrode substrate protrude from the second connection structure portion toward the center of the first sensor body when viewed in the first direction; The force sensor may be any one of those described in [1] to

[10] .

[0018]

[12] This disclosure relates to: The first connection structure includes a first buffer structure that buffers a force acting on the strain body. The force sensor may be any one of those described in [1] to

[11] .

[0019]

[13] This disclosure relates to: A space is formed between the first connection structure and the second connection structure, the first buffer structure is formed such that, when viewed in the third direction, the space bulges out toward an opposite side to the second connection structure in the second direction; The force sensor may be as described in

[12] .

[0020]

[14] This disclosure relates to: the first buffer structure is formed such that, when viewed in the third direction, the space bulges toward the second sensor body in the first direction and bulges toward an opposite side to the second connection structure in the second direction. The force sensor may be as described in

[13] .

[0021]

[15] This disclosure relates to: The second connection structure includes a second buffer structure that buffers a force acting on the strain body. The force sensor may be any one of those described in [1] to

[14] .

[0022]

[16] This disclosure relates to: A space is formed between the first connection structure and the second connection structure, the second buffer structure is formed such that, when viewed in the third direction, the space bulges out toward an opposite side to the first connection structure in the second direction. The force sensor may be as described in

[15] .

[0023]

[17] This disclosure relates to: A spring constant of the third connection structure is greater than a spring constant of the first connection structure and a spring constant of the second connection structure. The force sensor may be any one of those described in [1] to

[16] . Effect of the Invention

[0024] According to the present invention, the force sensor can be made smaller. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a perspective view showing an example of a robot to which the force sensor according to the first embodiment is applied. [Diagram 2] FIG. 2 is a cross-sectional view showing the force sensor according to the first embodiment, and corresponds to a cross section taken along line AA in FIG. 3, which will be described later. [Diagram 3] FIG. 3 is a plan view showing the force sensor of FIG. 2 with the force receiving body omitted. [Figure 4] FIG. 4 is a front view showing the first flexure body of FIG. [Diagram 5] FIG. 5 is a side view showing the first flexure body of FIG. [Figure 6] FIG. 6 is a plan view showing the first flexure body of FIG. [Figure 7] FIG. 7 is a planar development of the strain generating element of the force sensor shown in FIG. [Figure 8] FIG. 8 is a front view showing a schematic deformation state of the first flexure body in FIG. 4 when the first flexure body is subjected to a force in the X-axis direction positive side. [Figure 9] FIG. 9 is a side view that illustrates a deformation state of the first flexure body in FIG. 5 when the first flexure body is subjected to a force in the Y-axis direction positive side. [Figure 10A] FIG. 10A is a side view that illustrates a deformation state of the first flexure body in FIG. 5 when the first flexure body is subjected to a force in the Z-axis direction positive side. [Figure 10B] FIG. 10B is a side view that illustrates a deformation state of the first flexure body in FIG. 5 when the first flexure body is subjected to a force in the negative Z-axis direction. [Figure 11] FIG. 11 is a table showing changes in the capacitance value of each capacitance element in the strain bodies of FIGS. [Figure 12] FIG. 12 is a table showing changes in the capacitance value of each capacitance element in the force sensor of FIG. [Figure 13] FIG. 13 is a side view showing the first strain element of the force sensor according to the second embodiment. [Figure 14]FIG. 14 is a plan view showing the first flexure body of FIG. [Figure 15] FIG. 15 is a plan view showing a force sensor including the first strain body shown in FIGS. 13 and 14 with the force receiving body omitted. [Figure 16] FIG. 16 is a plan view showing a displacement electrode of the force sensor according to the third embodiment. [Figure 17] FIG. 17 is a side view showing the first strain element of the force sensor according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to this specification, the scale and the aspect ratio are appropriately changed and exaggerated from those of the actual objects for the convenience of illustration and understanding.

[0027] The geometric conditions, physical characteristics, terms specifying the degree of the geometric conditions or physical characteristics, and numerical values ​​indicating the geometric conditions or physical characteristics used in this specification may be interpreted without being bound by their strict meaning. These geometric conditions, physical characteristics, terms, and numerical values ​​may be interpreted to include a range within which similar functions can be expected. Examples of terms specifying geometric conditions include "length," "angle," "shape," "parallel," "orthogonal," and "same."

[0028] (First embodiment) A force sensor according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 12. FIG.

[0029] First, a robot 1 according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a perspective view showing an example of a robot 1 according to the present embodiment. A force sensor 10 according to the present embodiment is attached to the robot 1. Examples of the robot 1 include various robots such as industrial robots, collaborative robots, life support robots, medical robots, and service robots. For convenience, the following description will be given taking an industrial robot to which the force sensor 10 is attached as an example.

[0030] 1, the industrial robot 1 includes a robot body 2, a tool 3, a force sensor 10, and a controller 5. The robot body 2 includes a robot arm 4. The robot arm 4 has a multi-joint arm structure.

[0031] A force sensor 10 is attached to the tip of the robot arm 4. More specifically, the force sensor 10 is attached between the robot arm 4 and the tool 3. The force sensor 10 is electrically connected to the controller 5 via an electric cable (not shown). Examples of the tool 3 include an end effector (gripper, etc.) and a tool changer (neither of which are shown), etc.

[0032] The controller 5 performs force control of the robot 1 based on the electrical signal output from the force sensor 10. In this way, the operations of the robot body 2 and the tool 3 are controlled.

[0033] Hereinafter, a force sensor 10 according to an embodiment of the present invention will be described with reference to Figs. 2 to 7. Fig. 2 is a cross-sectional view showing the force sensor according to this embodiment, and corresponds to the cross section taken along line AA in Fig. 3. Fig. 3 is a plan view showing the force sensor of Fig. 2 with the force receiving body omitted. Fig. 4 is a front view showing the first flexure body of Fig. 2. Fig. 5 is a side view showing the first flexure body of Fig. 4, and Fig. 6 is a plan view showing the first flexure body of Fig. 4. Fig. 7 is a planar development of each flexure body of the force sensor shown in Fig. 3.

[0034] In the following description, an XYZ three-dimensional coordinate system is defined, the Z-axis direction (first direction) is the up-down direction, and the force sensor 10 is arranged so that the force receiving body 20 is arranged on the upper side and the fixed body 25 is arranged on the lower side. For this reason, the force sensor 10 according to this embodiment is not limited to being used in a position in which the Z-axis direction is the up-down direction. Also, it is arbitrary whether the force receiving body 20 or the fixed body 25 is arranged on the upper side or the lower side.

[0035] The force sensor 10 has a function of outputting a force acting in a predetermined axial direction and a moment acting around a predetermined rotation axis as an electric signal. However, this is not limited thereto, and the force sensor 10 may be configured to output only one of the force and the moment as an electric signal, or may be configured to output at least one axial component of the force or the moment as an electric signal.

[0036] 2 and 3, the force sensor 10 includes a force receiving body 20, a fixed body 25, strain generating bodies 30A to 30D, a detection element 70, a detection circuit 75, and an exterior body 80. Each of the components will be described in more detail below.

[0037] Force receiving body 20 is an example of a first sensor body. Force receiving body 20 is acted upon by a force or moment to be detected. This action causes force receiving body 20 to move relative to fixed body 25. In the example of FIG. 1 described above, force receiving body 20 is fixed to tool 3 with a bolt or the like, and receives a force or moment from tool 3. Strain generating bodies 30A to 30D are connected to force receiving body 20.

[0038] 3, in this embodiment, the planar shape of force receiving body 20 is circular. However, the planar shape of force receiving body 20 is not limited to a circle, and may be rectangular or any other shape. Force receiving body 20 may be formed in a flat plate shape.

[0039] As shown in FIG. 2, fixed body 25 is an example of a second sensor body. Fixed body 25 supports force receiving body 20. Fixed body 25 is disposed at a different position from force receiving body 20 in the Z-axis direction. More specifically, fixed body 25 is disposed on the negative side of force receiving body 20 in the Z-axis direction. Force receiving body 20 and fixed body 25 are disposed at different positions from each other in the Z-axis direction, and fixed body 25 is spaced apart from force receiving body 20. In the example of FIG. 1, fixed body 25 is fixed to the tip of robot arm 4 with a bolt or the like, and is supported by robot main body 2. Strain generating bodies 30A to 30D are connected to fixed body 25.

[0040] As shown in FIG. 3, in this embodiment, the planar shape of fixed body 25 is circular, similar to force receiving body 20. When viewed in the Z-axis direction, fixed body 25 overlaps force receiving body 20. However, the planar shape of fixed body 25 is not limited to a circle, and may be rectangular or any other shape. Fixed body 25 may be formed in a flat plate shape. At least one of the planar shapes of force receiving body 20 and fixed body 25 may be circular. In this case, one of the planar shapes of force receiving body 20 and fixed body 25 may be circular, and the other may be a shape other than circular.

[0041] 2 and 3, the flexure bodies 30A to 30D connect the force receiving body 20 and the fixed body 25. More specifically, the flexure bodies 30A to 30D are disposed between the force receiving body 20 and the fixed body 25, and the flexure bodies 30A to 30D are connected to the force receiving body 20 and the fixed body 25. The force receiving body 20 is supported by the fixed body 25 via these flexure bodies 30A to 30D.

[0042] In the present embodiment, the force receiving body 20 and the fixed body 25 may be connected by four flexure bodies 30A to 30D. The four flexure bodies 30A to 30D may include a first flexure body 30A, a second flexure body 30B, a third flexure body 30C, and a fourth flexure body 30D.

[0043] 3, when viewed in the Z-axis direction, the four flexure bodies 30A-30D are disposed at different positions from one another in the circumferential direction relative to the center O of the force receiving body 20. Each of the flexure bodies 30A-30D is disposed so that a second direction, which will be described later, extends in a direction from the center O of the force receiving body 20 toward the outside.

[0044] As shown in FIG. 3, when viewed in the Z-axis direction, the second direction (described later) of each of the flexure bodies 30A-30D may be arranged radially with respect to the center O of the force receiving body 20. Each of the flexure bodies 30A-30D may be arranged such that the second direction is along the radial direction with respect to the center O of the force receiving body 20. The four flexure bodies 30A-30D may be arranged evenly in the circumferential direction with respect to the center O of the force receiving body 20 when viewed in the Z-axis direction. For example, when viewed in the Z-axis direction, the center O of the force receiving body 20 may be arranged between the first flexure body 30A and the third flexure body 30C. Similarly, the center O of the force receiving body 20 may be arranged between the second flexure body 30B and the fourth flexure body 30D.

[0045] More specifically, as shown in FIG. 3, when viewed in the Z-axis direction, the first flexure body 30A may be disposed on the Y-axis direction positive side with respect to the center O of the force receiving body 20. In this case, the second direction of the first flexure body 30A is along the Y-axis direction, and the first flexure body 30A is formed linearly along the Y-axis direction. Similarly, the second flexure body 30B may be disposed on the X-axis direction negative side with respect to the center O of the force receiving body 20. In this case, the second direction of the second flexure body 30B is along the X-axis direction, and the second flexure body 30B is formed linearly along the X-axis direction. The third flexure body 30C may be disposed on the Y-axis direction negative side with respect to the center O of the force receiving body 20. In this case, the second direction of the third flexure body 30C is along the Y-axis direction, and the third flexure body 30C is formed linearly along the Y-axis direction. The fourth flexure body 30D may be disposed on the X-axis direction positive side with respect to the center O of the force receiving body 20. In this case, the second direction of the fourth flexure body 30D is along the X-axis direction, and the fourth flexure body 30D is formed linearly along the X-axis direction.

[0046] The second direction of each of the flexure bodies 30A-30D is not limited to the example shown in Fig. 3, and may be any direction. Also, the second direction of each of the flexure bodies 30A-30D does not have to be along either the X-axis direction or the Y-axis direction as long as it is along a direction from the center O of the force receiving body 20 toward the outside.

[0047] The number of strain bodies connecting force receiving body 20 and fixed body 25 is not limited to four, and may be two, three, five or more, and is arbitrary. Force receiving body 20 and fixed body 25 may be connected by only one strain body, in which case, if detection element 70 is configured with two capacitance elements as shown in Fig. 4, it is possible to detect two-axis components of force, as described below. Detection element 70 may also be configured with only one capacitance element to detect one-axis component of force.

[0048] The flexure bodies 30A-30D according to this embodiment are configured to be elastically deformed and distorted by the action of a force or moment received by the force receiving body 20, and thus displaced. Here, of the four flexure bodies 30A-30D described above, the first flexure body 30A having the Y-axis direction as the second direction will be described as an example. The X-axis direction corresponds to the third direction of the first flexure body 30A. The third direction is a direction perpendicular to the first direction and perpendicular to the second direction. The second flexure body 30B, the third flexure body 30C, and the fourth flexure body 30D have the same configuration, and therefore a description of the common configuration will be omitted.

[0049] Next, the first flexure body 30A will be described in more detail. As shown in Fig. 4 to Fig. 6, the first flexure body 30A includes a first connection structure 31, a second connection structure 32, and a third connection structure 33.

[0050] 5, first connection structure 31 is connected to force receiving body 20. First connection structure 31 may be formed in an L-shape when viewed in the X-axis direction. First connection structure 31 may include an eleventh connection portion 34 and a twelfth connection portion 35. First connection structure 31 may be elastically deformable when a force or moment acts on force receiving body 20.

[0051] The eleventh connection portion 34 extends from the force receiving body 20 toward the fixed body 25. The eleventh connection portion 34 may extend in the Z-axis direction. The eleventh connection portion 34 includes a first connection end portion 36 located on the fixed body 25 side. The first connection end portion 36 faces the fixed body 25.

[0052] The twelfth connection portion 35 connects the third connection structure portion 33 and the eleventh connection portion 34. The twelfth connection portion 35 may extend in the Y-axis direction perpendicular to the Z-axis direction. The twelfth connection portion 35 extends in the Y-axis direction from the first connection end portion 36.

[0053] The second connection structure 32 is connected to the force receiving body 20. The second connection structure 32 may be formed in an L-shape when viewed in the X-axis direction. The second connection structure 32 is disposed at a position different from the first connection structure 31 in the Y-axis direction. The second connection structure 32 may be disposed on the Y-axis direction negative side of the first connection structure 31. The second connection structure 32 may be disposed at the same position as the first connection structure 31 in the X-axis direction. In this case, the first connection structure 31 and the second connection structure 32 are disposed along the Y-axis direction. The second connection structure 32 may include a 21st connection portion 37 and a 22nd connection portion 38. The second connection structure 32 may be elastically deformable when a force or moment acts on the force receiving body 20.

[0054] The 21st connection portion 37 extends from the force receiving body 20 toward the fixed body 25. The 21st connection portion 37 may extend in the Z-axis direction. The 21st connection portion 37 includes a second connection end portion 39 located on the fixed body 25 side. The second connection end portion 39 faces the fixed body 25 in a state in which the displacement portion 41, the first capacitance element C1, and the second capacitance element C2 are not present.

[0055] The 22nd connecting portion 38 connects the third connecting structure portion 33 and the 21st connecting portion 37. The 22nd connecting portion 38 may extend in the Y-axis direction perpendicular to the Z-axis direction. The 22nd connecting portion 38 extends in the Y-axis direction from the second connecting end portion 39. The 22nd connecting portion 38 may be formed in a straight line with the 12th connecting portion 35 described above.

[0056] The third connection structure 33 connects the first connection structure 31 and the second connection structure 32 to the fixed body 25. The third connection structure 33 may extend in the Z-axis direction. The third connection structure 33 is disposed between the first connection structure 31 and the second connection structure 32 in the Y-axis direction. The third connection structure 33 may be disposed at a position overlapping the central axis CL of the first flexure body 30A as shown in FIG. 5. The central axis CL is a line that passes through the center of the first flexure body 30A in the X-axis direction and the Y-axis direction and extends in the Z-axis direction. The third connection structure 33 may be disposed at the same position as the first connection structure 31 and the second connection structure 32 in the X-axis direction. In this case, the first connection structure 31, the second connection structure 32, and the third connection structure 33 are disposed along the Y-axis direction. The third connection structure 33 may be elastically deformable when a force or moment acts on the force receiving body 20.

[0057] The third connection structure portion 33 includes a third connection end portion 40 located on the side of the force receiving body 20. The third connection end portion 40 faces the force receiving body 20. The above-mentioned twelfth connection portion 35 and 22nd connection portion 38 may each extend in the Y-axis direction from the third connection end portion 40. For the first strain body 30A, the twelfth connection portion 35 extends from the third connection end portion 40 to the positive side in the Y-axis direction, and the 22nd connection portion 38 extends to the negative side in the Y-axis direction.

[0058] The first flexure body 30A may further include a displacement portion 41. As shown in Fig. 5, the displacement portion 41 may be disposed on one side of the central axis CL of the first flexure body 30A when viewed in the X-axis direction. The displacement portion 41 may be disposed on the Y-axis direction negative side of the central axis CL of the first flexure body 30A.

[0059] The displacement portion 41 may be connected to the second connection structure portion 32. The displacement portion 41 may be connected to a surface of the second connection structure portion 32 facing the fixed body 25. The displacement portion 41 may be connected to the 21st connection portion 37 of the second connection structure portion 32. More specifically, the displacement portion 41 may be connected to the second connection end portion 39 of the 21st connection portion 37. The displacement portion 41 may be connected to a surface of the second connection end portion 39 facing the fixed body 25 (corresponding to the lower surface of the second connection end portion 39 in FIG. 5). The displacement portion 41 may have a thickness in the Z-axis direction. This allows the surface of the displacement portion 41 facing the fixed body 25 to be closer to the fixed body 25 than the surface of the second connection end portion 39 facing the fixed body 25. However, the displacement portion 41 may be connected to a surface of the 22nd connection portion 38 facing the fixed body 25.

[0060] Of the respective flexure bodies 30A configured as described above, the first flexure body 30A may be integrally formed from a continuous material. The first flexure body 30A may be produced by machining (e.g., cutting) a single block of material, or may be produced by casting. The first flexure body 30A may be produced from a metal material such as an aluminum alloy or an iron alloy. The displacement portion 41 described above may be attached to the second connection structure part 32 as a separate part, or may be integrally formed with the second connection structure part 32 from a continuous material.

[0061] As shown in FIG. 3, the first flexure body 30A according to this embodiment is disposed on the positive side of the Y-axis direction with respect to the center O of the force receiving body 20 when viewed in the Z-axis direction. The second direction of the first flexure body 30A is along the Y-axis direction. The second connection structure 32 of the first flexure body 30A is disposed at a position closer to the center O of the force receiving body 20 than the first connection structure 31 of the first flexure body 30A. In other words, the second connection structure 32 is disposed radially inward of the force receiving body 20 than the first connection structure 31 and on the negative side of the Y-axis direction than the first connection structure 31. As a result, the displacement portion 41 of the first flexure body 30A is disposed radially inward of the force receiving body 20.

[0062] The second flexure body 30B according to this embodiment is disposed on the negative side of the X-axis direction with respect to the center O of the force receiving body 20 when viewed in the Z-axis direction. The second direction of the second flexure body 30B is along the X-axis direction. The second connection structure 32 of the second flexure body 30B is disposed at a position closer to the center O of the force receiving body 20 than the first connection structure 31 of the second flexure body 30B. In other words, the second connection structure 32 is disposed radially inward of the force receiving body 20 than the first connection structure 31 and on the positive side of the X-axis direction than the first connection structure 31. As a result, the displacement portion 41 of the second flexure body 30B is disposed radially inward of the force receiving body 20.

[0063] The third flexure body 30C according to this embodiment is disposed on the negative side of the Y axis direction with respect to the center O of the force receiving body 20 when viewed in the Z axis direction. The second direction of the third flexure body 30C is along the Y axis direction. The second connection structure 32 of the third flexure body 30C is disposed at a position closer to the center O of the force receiving body 20 than the first connection structure 31 of the third flexure body 30C. In other words, the second connection structure 32 is disposed radially inward of the force receiving body 20 than the first connection structure 31 and on the positive side of the Y axis direction than the first connection structure 31. As a result, the displacement portion 41 of the third flexure body 30C is disposed radially inward of the force receiving body 20.

[0064] The fourth flexure body 30D according to the present embodiment is disposed on the positive side of the X-axis direction with respect to the center O of the force receiving body 20 when viewed in the Z-axis direction. The second direction of the fourth flexure body 30D is along the X-axis direction. The second connection structure 32 of the fourth flexure body 30D is disposed at a position closer to the center O of the force receiving body 20 than the first connection structure 31 of the fourth flexure body 30D. In other words, the second connection structure 32 is disposed radially inward of the force receiving body 20 than the first connection structure 31 and on the negative side of the X-axis direction than the first connection structure 31. As a result, the displacement portion 41 of the fourth flexure body 30D is disposed radially inward of the force receiving body 20.

[0065] Next, the detection element 70 according to the present embodiment will be described.

[0066] The detection element 70 is configured to detect a displacement caused by elastic deformation of each of the above-mentioned strain bodies 30A to 30D. The detection element 70 according to the present embodiment may include a fixed electrode substrate provided on the fixed body 25, and a displacement electrode substrate displaced together with the second connection structure portion 32 of each of the strain bodies 30A to 30D. The detection element 70 according to the present embodiment may include a first capacitance element C1 to an eighth capacitance element C8. Each of the capacitance elements C1 to C8 may be composed of a fixed electrode substrate and a displacement electrode substrate.

[0067] 4 to 6, the first capacitance element C1 and the second capacitance element C2 each detect a change in capacitance value due to the displacement of the second connection structure portion 32 of the first strain body 30A. The first capacitance element C1 and the second capacitance element C2 are capacitance elements for the first strain body 30A shown in FIGS.

[0068] The displacement electrode substrate displaced together with the second connection structure 32 of the first flexure body 30A may include a first displacement electrode substrate Ed1 and a second displacement electrode substrate Ed2. An example of one of the one-side displacement electrode substrate and the other-side displacement electrode substrate is the first displacement electrode substrate Ed1, and an example of the other is the second displacement electrode substrate Ed2. The fixed electrode substrate for the first flexure body 30A may include a first fixed electrode substrate Ef1 and a second fixed electrode substrate Ef2.

[0069] In the example shown in FIGS. 4 to 6, the first capacitance element C1 is composed of a first fixed electrode substrate Ef1 and a first displacement electrode substrate Ed1. The second capacitance element C2 is composed of a second fixed electrode substrate Ef2 and a second displacement electrode substrate Ed2. In this embodiment, the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are provided on the displacement portion 41 of the first strain generating body 30A. The first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 are provided on the fixed body 25.

[0070] 4 and 6, the first fixed electrode substrate Ef1 is disposed on the positive side of the X-axis direction with respect to the central axis CL of the first flexure body 30A. The second fixed electrode substrate Ef2 is disposed on the negative side of the X-axis direction with respect to the central axis CL of the first flexure body 30A.

[0071] As shown in FIG. 4, the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be integrated. More specifically, the fixed electrode of the first fixed electrode substrate Ef1 and the fixed electrode of the second fixed electrode substrate Ef2 are integrated to form a common fixed electrode Efc. The insulator of the first fixed electrode substrate Ef1 and the insulator of the second fixed electrode substrate Ef2 are integrated to form a common insulator IBfc. The common insulator IBfc may be joined to the fixed body 25 with an adhesive or the like, or may be fixed with a bolt or the like. The entire common insulator IBfc may be joined to the fixed body 25. However, the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be formed separately. In this case, the fixed electrode of the first fixed electrode substrate Ef1 and the fixed electrode of the second fixed electrode substrate Ef2 may be formed separately and spaced apart from each other. The insulator of the first fixed electrode substrate Ef1 and the insulator of the second fixed electrode substrate Ef2 may be formed separately, or may be integrated to form a common insulator IBfc.

[0072] As shown in Figs. 4 and 6, the first displacement electrode substrate Ed1 is disposed on the X-axis direction positive side with respect to the central axis CL of the first flexure body 30A. The first displacement electrode substrate Ed1 faces the above-mentioned first fixed electrode substrate Ef1. The second displacement electrode substrate Ed2 is disposed on the X-axis direction negative side with respect to the central axis CL of the first flexure body 30A. The second displacement electrode substrate Ed2 faces the above-mentioned second fixed electrode substrate Ef2. The first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 may be connected to the above-mentioned displacement portion 41 of the second connection structure portion 32, or may be connected to a surface of the displacement portion 41 facing the fixed body 25 (corresponding to the lower surface of the displacement portion 41 in Fig. 5).

[0073] As shown in FIG. 4, the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 each include a displacement electrode Ed and an insulator. The displacement electrode Ed of the first displacement electrode substrate Ed1 faces the fixed electrode of the first fixed electrode substrate Ef1, and the displacement electrode of the second displacement electrode substrate Ed2 faces the fixed electrode of the second fixed electrode substrate Ef2. The displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 may be formed separately and spaced apart from each other. The insulator is interposed between the displacement electrode Ed and the displacement portion 41. The insulator of the first displacement electrode substrate Ed1 and the insulator of the second displacement electrode substrate Ed2 may be integrated to form a common insulator IBdc. The common insulator IBdc may be joined to the displacement portion 41 with an adhesive or the like, or may be fixed with a bolt or the like. A part of the common insulator IBdc may be joined to the displacement portion 41. A support plate (not shown) may be interposed between the common insulator IBdc and the displacement portion 41. As described later, when the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are configured with an FPC substrate, the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 may be supported by a support plate.

[0074] 3 to 7, the first capacitance element C1 and the second capacitance element C2 are disposed at the same position in the Y-axis direction. That is, the displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 are disposed at the same position in the Y-axis direction. The first capacitance element C1 and the second capacitance element C2 are disposed on the negative side in the Y-axis direction with respect to the third connection structure portion 33 of the first strain generating body 30A.

[0075] As shown in FIG. 6, the Y-axis direction distance L2 may be greater than the X-axis direction distance L1. The X-axis direction distance L1 is the X-axis direction distance between the center of the first displacement electrode substrate Ed1 and the central axis CL of the first flexure body 30A. The X-axis direction distance between the center of the first displacement electrode substrate Ed1 and the central axis CL may be equal to the X-axis direction distance between the center of the second displacement electrode substrate Ed2 and the central axis CL. The Y-axis direction distance L2 is the Y-axis direction distance between the center of the first displacement electrode substrate Ed1 and the central axis CL of the first flexure body 30A. The Y-axis direction distance between the center of the first displacement electrode substrate Ed1 and the central axis CL may be equal to the Y-axis direction distance between the center of the second displacement electrode substrate Ed2 and the central axis CL. In FIG. 6, the central axis CL is shown as a dot.

[0076] In this embodiment, the planar shape of the common fixed electrode Efc obtained by integrating the fixed electrodes of the fixed electrode substrates Ef1 and Ef2 is rectangular. The planar shape of the displacement electrodes Ed of the displacement electrode substrates Ed1 and Ed2 is also rectangular. However, the planar shapes of the common fixed electrode Efc and the displacement electrodes Ed are not limited to rectangular, and may be other shapes such as circular, polygonal, or elliptical.

[0077] When viewed in the Z-axis direction, the planar shape of the displacement electrode Ed of the first displacement electrode substrate Ed1 may be smaller than the planar shape of the common fixed electrode Efc. The size of the displacement electrode Ed and the size of the common fixed electrode Efc may be set so that the displacement electrode Ed of the first displacement electrode substrate Ed1 overlaps the common fixed electrode Efc as a whole when viewed in the Z-axis direction, even when the force receiving body 20 receives a force or moment and the first displacement electrode substrate Ed1 is displaced. This makes it possible to prevent the facing area of ​​the displacement electrode Ed and the common fixed electrode Efc from changing, and to prevent the change in the facing area from affecting the change in the capacitance value. Therefore, the capacitance value can be changed according to the change in the distance between the displacement electrode Ed and the common fixed electrode Efc. Here, the facing area refers to the area where the displacement electrode Ed and the common fixed electrode Efc overlap when viewed in the Z-axis direction. When the second connection structure portion 32 is tilted, the displacement electrode Ed, which is smaller than the common fixed electrode Efc, may be tilted and the facing area may change, but the inclination angle of the displacement electrode Ed in this case is small. As a result, the distance between the displacement electrode Ed and the common fixed electrode Efc is dominant in the change in capacitance value. For this reason, in this specification, the change in the opposing area due to the inclination of the displacement electrode Ed is not taken into consideration, and the change in capacitance value is considered to be caused by the change in the distance between the displacement electrode Ed and the common fixed electrode Efc. Note that in Fig. 8 and other figures described later, the inclination of the displacement electrode substrates Ed1 to Ed8 is exaggerated to make the drawing clearer.

[0078] Similarly, when viewed in the Z-axis direction, the planar shape of the displacement electrodes Ed of the second displacement electrode substrate Ed2 may be smaller than the common fixed electrode Efc. The planar shape of the displacement electrodes Ed of the second displacement electrode substrate Ed2 may be the same as the planar shape of the displacement electrodes Ed of the first displacement electrode substrate Ed1.

[0079] The planar shape of the common fixed electrode Efc of the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be the same size as the planar shape of the common insulator IBfc of the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2. However, the planar shape of the common fixed electrode Efc may be smaller than the planar shape of the common insulator IBfc. The planar shapes of the displacement electrodes Ed of the first displacement electrode substrate Ed1 and the displacement electrodes Ed of the second displacement electrode substrate Ed2 may each be smaller than the planar shape of the common insulator IBdc of the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2.

[0080] The insulator may be made of an insulating material such as a polyimide film, a glass epoxy resin, ceramic, etc. A metal thin film constituting the fixed electrode or the displacement electrode described above is formed on the insulator.

[0081] The fixed electrode substrates Ef1 and Ef2 may be constituted by an FPC substrate (flexible printed circuit board). The FPC substrate is a printed substrate formed in a thin film shape and has flexibility. The FPC substrate is a polyimide film on which a metal thin film constituting electrodes and wiring is formed. The parts of the FPC substrate corresponding to the fixed electrode substrates Ef1 and Ef2 may be fixed to the fixed body 25. The FPC substrate may include wiring connecting the common fixed electrode Efc to the detection circuit 75. The displacement electrode substrates Ed1 and Ed2 may be constituted by an FPC substrate in the same manner. In this case, the parts corresponding to the displacement electrode substrates Ed1 and Ed2 may be fixed to the displacement portion 41. The FPC substrate may include wiring connecting the displacement electrode Ed to the detection circuit 75.

[0082] The above-mentioned configuration of the first flexure body 30A and the corresponding detection element 70 can be similarly applied to the second flexure body 30B, the third flexure body 30C, and the fourth flexure body 30D.

[0083] 3, the third capacitance element C3 and the fourth capacitance element C4 each detect a change in capacitance value due to the displacement of the second connection structure portion 32 of the second flexure body 30B. The third capacitance element C3 and the fourth capacitance element C4 are capacitance elements for the second flexure body 30B.

[0084] The displacement electrode substrate displaced together with the second connection structure portion 32 of the second flexure body 30B may include a third displacement electrode substrate Ed3 and a fourth displacement electrode substrate Ed4. An example of one of the one-side displacement electrode substrate and the other-side displacement electrode substrate is the third displacement electrode substrate Ed3, and an example of the other is the fourth displacement electrode substrate Ed4. The fixed electrode substrate for the second flexure body 30B may include a third fixed electrode substrate Ef3 and a fourth fixed electrode substrate Ef4.

[0085] As shown in Fig. 7, the third capacitance element C3 is composed of a third fixed electrode substrate Ef3 and a third displacement electrode substrate Ed3. The fourth capacitance element C4 is composed of a fourth fixed electrode substrate Ef4 and a fourth displacement electrode substrate Ed4. In this embodiment, the third displacement electrode substrate Ed3 and the fourth displacement electrode substrate Ed4 are provided on the displacement portion 41 of the second strain generating body 30B. The third fixed electrode substrate Ef3 and the fourth fixed electrode substrate Ef4 are provided on the fixed body 25.

[0086] The third fixed electrode substrate Ef3 is disposed on the positive side in the Y-axis direction with respect to the central axis CL of the second flexure body 30B. The fourth fixed electrode substrate Ef4 is disposed on the negative side in the Y-axis direction with respect to the central axis CL of the second flexure body 30B. In this embodiment, the third fixed electrode substrate Ef3 and the fourth fixed electrode substrate Ef4 are integrated and configured similarly to the above-mentioned fixed electrode substrates Ef1 and Ef2.

[0087] The third displacement electrode substrate Ed3 is disposed on the Y-axis direction positive side with respect to the central axis CL of the second flexure body 30B. The third displacement electrode substrate Ed3 faces the above-mentioned third fixed electrode substrate Ef3. The fourth displacement electrode substrate Ed4 is disposed on the Y-axis direction negative side with respect to the central axis CL of the second flexure body 30B. The fourth displacement electrode substrate Ed4 faces the above-mentioned fourth fixed electrode substrate Ef4. The displacement electrode substrates Ed3, Ed4 are configured similarly to the above-mentioned displacement electrode substrates Ed1, Ed2.

[0088] 3 and 7, the third capacitance element C3 and the fourth capacitance element C4 are disposed at the same position in the X-axis direction. That is, the displacement electrode Ed of the third displacement electrode substrate Ed3 and the displacement electrode Ed of the fourth displacement electrode substrate Ed4 are disposed at the same position in the X-axis direction. The third capacitance element C3 and the fourth capacitance element C4 are disposed on the positive side in the X-axis direction with respect to the third connection structure portion 33 of the second strain body 30B.

[0089] 3, the fifth capacitive element C5 and the sixth capacitive element C6 each detect a change in capacitance value due to the displacement of the second connection structure portion 32 of the third flexure body 30C. The fifth capacitive element C5 and the sixth capacitive element C6 are capacitive elements for the third flexure body 30C.

[0090] The displacement electrode substrate displaced together with the second connection structure portion 32 of the third flexure body 30C may include a fifth displacement electrode substrate Ed5 and a sixth displacement electrode substrate Ed6. One example of the one-side displacement electrode substrate and the other-side displacement electrode substrate is the fifth displacement electrode substrate Ed5, and the other example is the sixth displacement electrode substrate Ed6. The fixed electrode substrate for the third flexure body 30C may include a fifth fixed electrode substrate Ef5 and a sixth fixed electrode substrate Ef6.

[0091] As shown in Fig. 7, the fifth capacitance element C5 is composed of a fifth fixed electrode substrate Ef5 and a fifth displacement electrode substrate Ed5. The sixth capacitance element C6 is composed of a sixth fixed electrode substrate Ef6 and a sixth displacement electrode substrate Ed6. In this embodiment, the fifth displacement electrode substrate Ed5 and the sixth displacement electrode substrate Ed6 are provided on the displacement portion 41 of the third strain body 30C. The fifth fixed electrode substrate Ef5 and the sixth fixed electrode substrate Ef6 are provided on the fixed body 25.

[0092] The fifth fixed electrode substrate Ef5 is disposed on the negative side in the X-axis direction with respect to the central axis CL of the third flexure body 30C. The sixth fixed electrode substrate Ef6 is disposed on the positive side in the X-axis direction with respect to the central axis CL of the third flexure body 30C. In this embodiment, the fifth fixed electrode substrate Ef5 and the sixth fixed electrode substrate Ef6 are integrated and configured similarly to the above-mentioned fixed electrode substrates Ef1 and Ef2.

[0093] The fifth displacement electrode substrate Ed5 is disposed on the negative side in the X-axis direction with respect to the central axis CL of the third flexure body 30C. The fifth displacement electrode substrate Ed5 faces the fifth fixed electrode substrate Ef5 described above. The sixth displacement electrode substrate Ed6 is disposed on the positive side in the X-axis direction with respect to the central axis CL of the third flexure body 30C. The sixth displacement electrode substrate Ed6 faces the sixth fixed electrode substrate Ef6 described above. The displacement electrode substrates Ed5 and Ed6 are configured similarly to the displacement electrode substrates Ed1 and Ed2 described above.

[0094] 3 and 7, the fifth capacitance element C5 and the sixth capacitance element C6 are disposed at the same position in the Y-axis direction. That is, the displacement electrode Ed of the fifth displacement electrode substrate Ed5 and the displacement electrode Ed of the sixth displacement electrode substrate Ed6 are disposed at the same position in the Y-axis direction. The fifth capacitance element C5 and the sixth capacitance element C6 are disposed on the Y-axis direction positive side with respect to the third connection structure portion 33 of the third flexure body 30C.

[0095] 3, the seventh capacitive element C7 and the eighth capacitive element C8 each detect a change in capacitance value due to the displacement of the second connection structure portion 32 of the fourth flexure body 30D. The seventh capacitive element C7 and the eighth capacitive element C8 are capacitive elements for the fourth flexure body 30D.

[0096] The displacement electrode substrate displaced together with the second connection structure portion 32 of the fourth flexure body 30D may include a seventh displacement electrode substrate Ed7 and an eighth displacement electrode substrate Ed8. One example of the one-side displacement electrode substrate and the other-side displacement electrode substrate is the seventh displacement electrode substrate Ed7, and the other example is the eighth displacement electrode substrate Ed8. The fixed electrode substrate for the fourth flexure body 30D may include a seventh fixed electrode substrate Ef7 and an eighth fixed electrode substrate Ef8.

[0097] As shown in FIG. 7, the seventh capacitance element C7 is composed of a seventh fixed electrode substrate Ef7 and a seventh displacement electrode substrate Ed7. The eighth capacitance element C8 is composed of an eighth fixed electrode substrate Ef8 and an eighth displacement electrode substrate Ed8. In this embodiment, the seventh displacement electrode substrate Ed7 and the eighth displacement electrode substrate Ed8 are provided on the displacement portion 41 of the fourth flexure body 30D. The seventh fixed electrode substrate Ef7 and the eighth fixed electrode substrate Ef8 are provided on the fixed body 25.

[0098] The seventh fixed electrode substrate Ef7 is disposed on the negative side in the Y-axis direction with respect to the central axis CL of the fourth flexure body 30D. The eighth fixed electrode substrate Ef8 is disposed on the positive side in the Y-axis direction with respect to the central axis CL of the fourth flexure body 30D. In this embodiment, the seventh fixed electrode substrate Ef7 and the eighth fixed electrode substrate Ef8 are integrated and configured similarly to the above-mentioned fixed electrode substrates Ef1 and Ef2.

[0099] The seventh displacement electrode substrate Ed7 is disposed on the negative side in the Y-axis direction with respect to the central axis CL of the fourth flexure body 30D. The seventh displacement electrode substrate Ed7 faces the above-mentioned seventh fixed electrode substrate Ef7. The eighth displacement electrode substrate Ed8 is disposed on the positive side in the Y-axis direction with respect to the central axis CL of the fourth flexure body 30D. The eighth displacement electrode substrate Ed8 faces the above-mentioned eighth fixed electrode substrate Ef8. The displacement electrode substrates Ed7 and Ed8 are configured similarly to the above-mentioned displacement electrode substrates Ed1 and Ed2.

[0100] 3 and 7, the seventh capacitance element C7 and the eighth capacitance element C8 are disposed at the same position in the X-axis direction. That is, the displacement electrode Ed of the seventh displacement electrode substrate Ed7 and the displacement electrode Ed of the eighth displacement electrode substrate Ed8 are disposed at the same position in the X-axis direction. The seventh capacitance element C7 and the eighth capacitance element C8 are disposed on the negative side in the X-axis direction with respect to the third connection structure portion 33 of the fourth flexure body 30D.

[0101] As shown in Fig. 2, the detection circuit 75 outputs an electric signal indicating the force or moment acting on the strain bodies 30A-30D based on the detection result of the detection element 70. The detection circuit 75 may have a calculation function constituted by, for example, a microprocessor. The detection circuit 75 may also have an A / D conversion function for converting an analog signal received from the detection element 70 described above into a digital signal, and a signal amplification function. The detection circuit 75 may include a terminal for outputting an electric signal, and the electric signal is transmitted from this terminal to the controller 5 described above via an electric cable (not shown).

[0102] As shown in Figs. 2 and 3, the exterior body 80 is configured to cover the four flexure bodies 30A to 30D from the outside when viewed in the Z-axis direction. The exterior body 80 may be a cylindrical housing constituting the force sensor 10. The flexure bodies 30A to 30D are housed in the exterior body 80. In this embodiment, the planar cross-sectional shape (shape in a cross section along the XY plane) of the exterior body 80 may be a circular frame shape. A buffer member 81 may be interposed in the gap between the force receiving body 20 and the exterior body 80. The buffer member 81 may be formed of a flexible material that is elastically deformable, such as rubber or sponge.

[0103] Next, a method for detecting a force or moment acting on the force sensor 10 according to the present embodiment configured as described above will be described with reference to Figs. 8 to 10B. Fig. 8 is a front view showing a deformation state of the first flexure body 30A when the first flexure body of Fig. 4 receives a force Fx in the positive direction of the X-axis direction, and Fig. 9 is a side view showing a deformation state of the first flexure body 30A when the first flexure body of Fig. 5 receives a force Fy in the positive direction of the Y-axis direction. Fig. 10A is a side view showing a deformation state of the first flexure body 30A when the first flexure body 30A of Fig. 5 receives a force Fz in the positive direction of the Z-axis direction. Fig. 10B is a side view showing a deformation state of the first flexure body 30A when the first flexure body 30A of Fig. 5 receives a force Fz in the negative direction of the Z-axis direction.

[0104] When the force receiving body 20 is subjected to a force or moment, the force or moment is transmitted to the first flexure body 30A to the fourth flexure body 30D. More specifically, the force or moment is transmitted to the first connection structure 31, the second connection structure 32, and the third connection structure 33, and elastic deformation occurs. This causes a displacement in the displacement portion 41. Therefore, the distance between each of the fixed electrode substrates Ef1 to Ef8 of the detection element 70 and the corresponding displacement electrode substrates Ed1 to Ed8 changes, and the capacitance value of each of the capacitance elements C1 to C8 changes. This change in capacitance value is detected by the detection element 70 as a displacement occurring in the flexure bodies 30A to 30D. In this case, the change in capacitance value of each of the capacitance elements C1 to C8 may differ. Therefore, the detection circuit 75 can detect the direction and magnitude of the force or moment acting on the force receiving body 20 based on the change in the capacitance value of each of the capacitance elements C1 to C8 detected by the detection element 70.

[0105] Here, first, using the first strain body 30A as an example, we will explain the changes in the capacitance values ​​of the first capacitance element C1 and the second capacitance element C2 when a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a force Fz in the Z-axis direction are applied.

[0106] (When +Fx is applied) When a force Fx acts on the first flexure body 30A in the X-axis direction positive direction, as shown in Fig. 8, the first connection structure 31, the second connection structure 32, and the third connection structure 33 of the first flexure body 30A elastically deform, and each of the connection structures 31 to 33 tilts so as to fall toward the X-axis direction positive side. In other words, the first connection structure 31, the second connection structure 32, and the third connection structure 33 rotate clockwise when viewed toward the Y-axis direction positive side (when viewed toward the paper surface of Fig. 8). In general, each of the connection structures 31 to 33 rotates around the connection point between the third connection structure 33 and the fixed body 25. In conjunction with the second connection structure 32, the displacement portion 41 rotates clockwise and tilts.

[0107] The first displacement electrode substrate Ed1 approaches the first fixed electrode substrate Ef1, and the inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 decreases. This causes the capacitance value of the first capacitance element C1 to increase. Meanwhile, the second displacement electrode substrate Ed2 moves away from the second fixed electrode substrate Ef2, and the inter-electrode distance (distance in the Z-axis direction) between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases. This causes the capacitance value of the second capacitance element C2 to decrease.

[0108] (When -Fx is applied) When a force Fx acts on the first strain body 30A in the negative X-axis direction, a phenomenon occurs that is opposite to that shown in Fig. 8, although this is not shown in the figure. That is, the capacitance value of the first capacitance element C1 decreases, and the capacitance value of the second capacitance element C2 increases.

[0109] (When +Fy is applied) When a force Fy acts on the first strain body 30A in the Y-axis direction positive direction, the first connection structure 31, the second connection structure 32, and the third connection structure 33 are elastically deformed and inclined so as to fall toward the Y-axis direction positive direction, as shown in FIG. 9. In other words, the first connection structure 31, the second connection structure 32, and the third connection structure 33 rotate counterclockwise when viewed toward the X-axis direction positive side (when viewed toward the paper surface of FIG. 9). In conjunction with the second connection structure 32, the displacement portion 41 rotates counterclockwise and inclined. In general, each of the connection structures 31 to 33 rotates around the connection point between the third connection structure 33 and the fixed body 25. In this case, the displacement portion 41 is displaced in a direction away from the fixed body 25.

[0110] The first displacement electrode substrate Ed1 moves away from the first fixed electrode substrate Ef1, and the inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 increases. As a result, the capacitance value of the first capacitance element C1 decreases. Similarly, the second displacement electrode substrate Ed2 moves away from the second fixed electrode substrate Ef2, and the inter-electrode distance (distance in the Z-axis direction) between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases. As a result, the capacitance value of the second capacitance element C2 decreases.

[0111] (When -Fy is applied) When a force Fy acts on the first strain body 30A in the negative Y-axis direction, a phenomenon occurs that is opposite to that shown in Fig. 9, although this is not shown in the figure. That is, the capacitance value of the first capacitance element C1 increases, and the capacitance value of the second capacitance element C2 increases.

[0112] (When +Fz is applied) When a force Fz acts on the first strain body 30A in the Z-axis direction positive side, the first connection structure 31 and the second connection structure 32 are elastically deformed as shown in Fig. 10A. In this case, the 21st connection portion 37 of the second connection structure 32 is displaced in the Z-axis direction positive side, and the 22nd connection portion 38 is inclined. In conjunction with the second connection structure 32, the displacement portion 41 is displaced in the Z-axis direction positive side. In this case, the displacement portion 41 is displaced in a direction away from the fixed body 25.

[0113] The first displacement electrode substrate Ed1 moves away from the first fixed electrode substrate Ef1, and the inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 increases. As a result, the capacitance value of the first capacitance element C1 decreases. Similarly, the second displacement electrode substrate Ed2 moves away from the second fixed electrode substrate Ef2, and the inter-electrode distance (distance in the Z-axis direction) between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases. As a result, the capacitance value of the second capacitance element C2 decreases.

[0114] (When -Fz is applied) When a force Fz acts on the first strain body 30A in the negative Z-axis direction, as shown in FIG. 10B, the opposite phenomenon to that shown in FIG. 10A occurs.

[0115] When a force Fz acts on the first strain body 30A in the negative Z-axis direction, the first connection structure 31 and the second connection structure 32 are elastically deformed as shown in Fig. 10B. In this case, the 21st connection portion 37 of the second connection structure 32 is displaced in the negative Z-axis direction, and the 22nd connection portion 38 is inclined. In conjunction with the second connection structure 32, the displacement portion 41 is displaced in the negative Z-axis direction. In this case, the displacement portion 41 is displaced in a direction approaching the fixed body 25.

[0116] The first displacement electrode substrate Ed1 approaches the first fixed electrode substrate Ef1, and the inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 decreases. This causes the capacitance value of the first capacitance element C1 to increase. Similarly, the second displacement electrode substrate Ed2 approaches the second fixed electrode substrate Ef2, and the inter-electrode distance (distance in the Z-axis direction) between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 decreases. This causes the capacitance value of the second capacitance element C2 to increase.

[0117] Here, changes in the electrostatic capacitance value of each of the capacitive elements C1 and C2 provided in the first flexure body 30A shown in Fig. 4 are shown in Fig. 11. Fig. 11 is a table showing changes in the electrostatic capacitance value of each of the capacitive elements C1 and C2 in the first flexure body 30A of Figs. 4 to 6.

[0118] FIG. 11 shows the change in capacitance value of the capacitance elements C1 and C2 with respect to a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a force Fz in the Z-axis direction. A decrease in capacitance value is indicated by "- (minus)", and an increase in capacitance value is indicated by "+ (plus)". For example, "+" is shown for C1 in the row of Fx in the table shown in FIG. 11, which indicates that the capacitance value of the first capacitance element C1 increases when a force of +Fx is applied as described above. On the other hand, "-" is shown for C2 in the row of Fx in the table shown in FIG. 11, which indicates that the capacitance value of the second capacitance element C2 decreases when a force of +Fx is applied as described above. For simplicity, in FIG. 11, the change in capacitance value is simply indicated by a sign.

[0119] From the table shown in FIG. 11, in the force sensor 10 in which the force receiving body 20 and the fixed body 25 are connected only by the first strain body 30A, the forces Fx, Fy, and Fz acting on the force receiving body 20 can be calculated by the following formulas. In the following formulas, for convenience, the force or moment and the change in capacitance value are connected with "=". However, since the force or moment and the capacitance value are different physical quantities, the force is actually calculated by converting the change in capacitance value. C1 and C2 in the following formulas indicate the change in capacitance value in each capacitance element.

number

number

number

[0120] As shown in FIG. 11, in the force sensor 10 in which the force receiving body 20 and the fixed body 25 are connected only by the first strain generating body 30A, the force Fx in the X-axis direction can be detected by the difference between the capacitance value of the first capacitance element C1 and the capacitance value of the second capacitance element C2. That is, as shown in the above formula (1), the output value of the force Fx can be calculated by the difference between the amount of change in the capacitance value of the first capacitance element C1 and the amount of change in the capacitance value of the second capacitance element C2. Even if the capacitance value of the first capacitance element C1 and the capacitance value of the second capacitance element C2 each contain an influence due to disturbances such as noise or ambient temperature, the influence can be offset by the difference in the above formula (1). Therefore, the output value of the force Fx can be prevented from being influenced by disturbances, and the force sensor 10 can have high performance.

[0121] As shown in the above formulas (2) and (3), the amount of change in capacitance decreases in both Fy and Fz, and the formulas are the same. This makes it difficult to determine whether the detected force is Fy or Fz. For this reason, the force sensor 10 using only one first strain body 30A can be used when either one of the forces Fy and Fz and the force Fx act. In this case, the force sensor 10 is a force sensor capable of detecting two-axis components.

[0122] Next, in the force sensor 10 shown in Fig. 7, changes in the capacitance value of each of the capacitance elements C1 to C8 when a force Fx in the X-axis direction, a force Fy in the Y-axis direction, a force Fz in the Z-axis direction, a moment Mx about the X-axis, a moment My about the Y-axis, and a moment Mz about the Z-axis are applied will be described with reference to Fig. 12. Fig. 12 is a table showing changes in the capacitance value of each capacitance element in the force sensor of Fig. 7.

[0123] (When +Fx is applied) First, a case where force Fx acts on force receiving body 20 shown in FIG. 7 in the positive direction in the X-axis direction will be described.

[0124] In this case, the first flexure body 30A elastically deforms in the same manner as the first flexure body 30A shown in Fig. 8, and the capacitance value of the first capacitance element C1 increases and the capacitance value of the second capacitance element C2 decreases. In this case, since the distance in the X-axis direction between the center of the first displacement electrode substrate Ed1 and the central axis CL (corresponding to L1 in Fig. 6) is relatively small, the increase in the capacitance value of the first capacitance element C1 becomes relatively small. Similarly, the decrease in the capacitance value of the second capacitance element C2 becomes relatively small.

[0125] The second flexure body 30B is elastically deformed in the opposite direction to the first flexure body 30A shown in FIG. 9, and the capacitance value of the third capacitance element C3 increases, and the capacitance value of the fourth capacitance element C4 increases. More specifically, the second connection structure 32 of the second flexure body 30B rotates and tilts clockwise when viewed toward the Y-axis direction positive side. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the second flexure body 30B and the fixed body 25. Since the X-axis direction distance (corresponding to L2 in FIG. 6) between the center of the third displacement electrode substrate Ed3 and the central axis CL is relatively large, the displacement amount of the third displacement electrode substrate Ed3 in the direction approaching the third fixed electrode substrate Ef3 is relatively large. Therefore, when a force Fx acts on the force receiving body 20 in the X-axis direction positive side, the increase amount of the capacitance value of the third capacitance element C3 becomes relatively large. For this reason, C3 in the row of Fx in the table shown in Fig. 12 is marked with "++." Similarly, the increase in the capacitance value of the fourth capacitance element C4 is relatively large, so C4 in the row of Fx in the table shown in Fig. 12 is marked with "++."

[0126] The third flexure body 30C elastically deforms in the opposite direction to the first flexure body 30A shown in Fig. 8, and the capacitance value of the fifth capacitance element C5 decreases and the capacitance value of the sixth capacitance element C6 increases. In this case, since the distance in the X-axis direction between the center of the fifth displacement electrode substrate Ed5 and the central axis CL (corresponding to L1 in Fig. 6) is relatively small, the decrease in the capacitance value of the fifth capacitance element C5 becomes relatively small. Similarly, the increase in the capacitance value of the sixth capacitance element C6 becomes relatively small.

[0127] The fourth flexure body 30D is elastically deformed in the same manner as the first flexure body 30A shown in FIG. 9, and the capacitance value of the seventh capacitance element C7 decreases, and the capacitance value of the eighth capacitance element C8 decreases. More specifically, the second connection structure 32 of the fourth flexure body 30D rotates and tilts clockwise when viewed toward the Y-axis direction positive side. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the fourth flexure body 30D and the fixed body 25. Since the X-axis direction distance (corresponding to L2 in FIG. 6) between the center of the seventh displacement electrode substrate Ed7 and the central axis CL is relatively large, the displacement amount of the seventh displacement electrode substrate Ed7 in the direction away from the seventh fixed electrode substrate Ef7 is relatively large. Therefore, when a force Fx acts on the force receiving body 20 in the X-axis direction positive side, the decrease amount of the capacitance value of the seventh capacitance element C7 is relatively large. For this reason, C7 in the row of Fx in the table shown in Fig. 12 is marked with "--". Similarly, the amount of decrease in the capacitance value of the eighth capacitance element C8 is relatively large, so C8 in the row of Fx in the table shown in Fig. 12 is marked with "--".

[0128] (When +Fy is applied) Next, a case will be described where force Fy acts on force receiving body 20 in the Y-axis direction positive direction. In the following description as well, the symbols in the table of FIG. 12 are determined according to the change in capacitance value as described above.

[0129] The first flexure body 30A is elastically deformed in the same manner as the first flexure body 30A shown in FIG. 9, and the capacitance value of the first capacitance element C1 decreases, and the capacitance value of the second capacitance element C2 decreases. More specifically, the second connection structure 32 of the first flexure body 30A rotates and tilts counterclockwise when viewed toward the X-axis direction positive side. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the first flexure body 30A and the fixed body 25. Since the Y-axis direction distance (corresponding to L2 in FIG. 6) between the center of the first displacement electrode substrate Ed1 and the central axis CL is relatively large, the displacement amount of the first displacement electrode substrate Ed1 in the direction away from the first fixed electrode substrate Ef1 is relatively large. Therefore, when a force Fy acts on the force receiving body 20 in the Y-axis direction positive side, the decrease amount of the capacitance value of the first capacitance element C1 is relatively large. For this reason, C1 in the row of Fy in the table shown in Fig. 12 is marked with "--". Similarly, the amount of decrease in the capacitance value of the second capacitance element C2 is relatively large, so C2 in the row of Fy in the table shown in Fig. 12 is marked with "--".

[0130] The second flexure body 30B elastically deforms in the same manner as the first flexure body 30A shown in Fig. 8, and the capacitance value of the third capacitance element C3 increases and the capacitance value of the fourth capacitance element C4 decreases. In this case, since the Y-axis distance (corresponding to L1 in Fig. 6) between the center of the third displacement electrode substrate Ed3 and the central axis CL is relatively small, the increase in the capacitance value of the third capacitance element C3 becomes relatively small. Similarly, the decrease in the capacitance value of the fourth capacitance element C4 becomes relatively small.

[0131] The third flexure body 30C is elastically deformed in the opposite direction to the first flexure body 30A shown in FIG. 9, and the capacitance value of the fifth capacitance element C5 increases, and the capacitance value of the sixth capacitance element C6 increases. More specifically, the second connection structure 32 of the third flexure body 30C rotates and tilts counterclockwise when viewed toward the X-axis direction positive side. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the third flexure body 30C and the fixed body 25. Since the Y-axis direction distance (corresponding to L2 in FIG. 6) between the center of the fifth displacement electrode substrate Ed5 and the central axis CL is relatively large, the displacement amount of the fifth displacement electrode substrate Ed5 in the direction approaching the fifth fixed electrode substrate Ef5 is relatively large. Therefore, when a force Fy acts on the force receiving body 20 in the Y-axis direction positive side, the increase amount of the capacitance value of the fifth capacitance element C5 is relatively large. For this reason, C5 in the row of Fy in the table shown in Fig. 12 is marked with "++." Similarly, the increase in the capacitance value of the sixth capacitance element C6 is relatively large, so C6 in the row of Fy in the table shown in Fig. 12 is marked with "++."

[0132] The fourth flexure body 30D elastically deforms in the opposite direction to the first flexure body 30A shown in Fig. 8, and the capacitance value of the seventh capacitance element C7 decreases and the capacitance value of the eighth capacitance element C8 increases. In this case, since the distance in the Y-axis direction between the center of the seventh displacement electrode substrate Ed7 and the central axis CL (corresponding to L1 in Fig. 6) is relatively small, the decrease in the capacitance value of the seventh capacitance element C7 becomes relatively small. Similarly, the increase in the capacitance value of the eighth capacitance element C8 becomes relatively small.

[0133] (When +Fz is applied) Next, a case will be described where force Fz acts on force receiving body 20 in the Z-axis direction positive direction. In the following description as well, the symbols in the table of FIG. 12 are determined according to the change in capacitance value as described above.

[0134] In this case, the first flexure body 30A is elastically deformed in the same manner as the first flexure body 30A shown in FIG. 10A, and the capacitance value of the first capacitance element C1 decreases, and the capacitance value of the second capacitance element C2 decreases. More specifically, the 22nd connection portion 38 of the first flexure body 30A is inclined. Since the Y-axis distance (corresponding to L2 in FIG. 6) between the center of the first displacement electrode substrate Ed1 and the central axis CL is relatively large, the displacement amount of the first displacement electrode substrate Ed1 in the direction away from the first fixed electrode substrate Ef1 is relatively large. For this reason, C1 in the row of Fz in the table shown in FIG. 12 is "--". Similarly, the second capacitance element C2 to the eighth capacitance element C8 also decrease relatively greatly.

[0135] (When +Mx is applied) Next, a case will be described where a clockwise moment Mx (see FIG. 7) around the X-axis, i.e., toward the positive side in the X-axis direction, acts on force receiving body 20. In the following explanation as well, the symbols in the table of FIG. 12 are determined as described above according to the change in capacitance value.

[0136] In this case, the first strain body 30A is elastically deformed in the same manner as the first strain body 30A to which the force Fz directed toward the positive side in the Z-axis direction is applied as shown in FIG. 10A, and the capacitance value of the first capacitance element C1 decreases, and the capacitance value of the second capacitance element C2 decreases. As described above, since the Y-axis distance (corresponding to L2 in FIG. 6) between the center of the first displacement electrode substrate Ed1 and the central axis CL is relatively large, the displacement amount of the first displacement electrode substrate Ed1 in the direction away from the first fixed electrode substrate Ef1 is relatively large. Therefore, the decrease in the capacitance value of the first capacitance element C1 becomes relatively large. In addition, since the Y-axis distance (corresponding to L3 in FIG. 3) between the center of the first displacement electrode substrate Ed1 and the center O of the force receiving body 20 is larger than the Y-axis distance (corresponding to L1 in FIG. 6) between the center of the third displacement electrode substrate Ed3 and the center O of the force receiving body 20, the decrease in the capacitance value of the first capacitance element C1 becomes even larger. Similarly, the capacitance value of the second capacitance element C2 also decreases by a relatively large amount.

[0137] When viewed toward the X-axis direction positive side, the first connection structure 31, the second connection structure 32, and the third connection structure 33 of the second flexure body 30B rotate clockwise. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the second flexure body 30B and the fixed body 25. Therefore, the third displacement electrode substrate Ed3 moves away from the third fixed electrode substrate Ef3, and the inter-electrode distance between the third displacement electrode substrate Ed3 and the third fixed electrode substrate Ef3 increases. Therefore, the capacitance value of the third capacitance element C3 decreases. Since the Y-axis direction distance (corresponding to L1 in FIG. 6) between the center of the third displacement electrode substrate Ed3 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the third capacitance element C3 becomes relatively small. On the other hand, the fourth displacement electrode substrate Ed4 approaches the fourth fixed electrode substrate Ef4, and the inter-electrode distance between the fourth displacement electrode substrate Ed4 and the fourth fixed electrode substrate Ef4 decreases. As a result, the capacitance value of the fourth capacitance element C4 increases. Since the distance in the Y-axis direction between the center of the fourth displacement electrode substrate Ed4 and the central axis CL (corresponding to L1 in FIG. 6) is relatively small, the increase in the capacitance value of the fourth capacitance element C4 becomes relatively small.

[0138] The third strain body 30C is elastically deformed in the same manner as the first strain body 30A to which the force Fz directed toward the negative side in the Z-axis direction is applied as shown in FIG. 10B, and the capacitance value of the fifth capacitance element C5 increases, and the capacitance value of the sixth capacitance element C6 increases. As described above, since the Y-axis distance (corresponding to L2 in FIG. 6) between the center of the fifth displacement electrode substrate Ed5 and the central axis CL is relatively large, the displacement amount of the fifth displacement electrode substrate Ed5 in the direction approaching the fifth fixed electrode substrate Ef5 is relatively large. Therefore, the increase amount of the capacitance value of the fifth capacitance element C5 becomes relatively large. In addition, since the Y-axis distance (corresponding to L3 in FIG. 3) between the center of the fifth displacement electrode substrate Ed5 and the center O of the force receiving body 20 is larger than the Y-axis distance (corresponding to L1 in FIG. 6) between the center of the fourth displacement electrode substrate Ed4 and the center O of the force receiving body 20, the increase amount of the capacitance value of the fifth capacitance element C5 becomes even larger. Similarly, the increase amount of the capacitance value of the sixth capacitance element C6 becomes relatively large.

[0139] When viewed toward the X-axis positive side, the fourth flexure body 30D has the first connection structure 31, the second connection structure 32, and the third connection structure 33 rotated clockwise. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the fourth flexure body 30D and the fixed body 25. Therefore, the seventh displacement electrode substrate Ed7 approaches the seventh fixed electrode substrate Ef7, and the inter-electrode distance between the seventh displacement electrode substrate Ed7 and the seventh fixed electrode substrate Ef7 decreases. Therefore, the capacitance value of the seventh capacitance element C7 increases. Since the Y-axis distance (corresponding to L1 in FIG. 6) between the center of the seventh displacement electrode substrate Ed7 and the central axis CL is relatively small, the increase in the capacitance value of the seventh capacitance element C7 becomes relatively small. On the other hand, the eighth displacement electrode substrate Ed8 moves away from the eighth fixed electrode substrate Ef8, and the inter-electrode distance between the eighth displacement electrode substrate Ed8 and the eighth fixed electrode substrate Ef8 increases. As a result, the capacitance value of the eighth capacitance element C8 decreases. Since the distance in the Y-axis direction between the center of the eighth displacement electrode substrate Ed8 and the central axis line CL (corresponding to L1 in FIG. 6) is relatively small, the amount of decrease in the capacitance value of the eighth capacitance element C8 becomes relatively small.

[0140] (When +My is applied) Next, a case will be described where a moment My (see FIG. 7) around the Y-axis, i.e., clockwise toward the positive side in the Y-axis direction, acts on force receiving body 20. In the following explanation, the symbols in the table of FIG. 12 are determined as described above according to the change in capacitance value.

[0141] In this case, when the first flexure body 30A is viewed toward the Y-axis positive side, the first connection structure 31, the second connection structure 32, and the third connection structure 33 rotate clockwise. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the first flexure body 30A and the fixed body 25. Therefore, the first displacement electrode substrate Ed1 approaches the first fixed electrode substrate Ef1, and the inter-electrode distance between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 decreases. Therefore, the capacitance value of the first capacitance element C1 increases. Since the distance in the X-axis direction between the center of the first displacement electrode substrate Ed1 and the central axis line CL (corresponding to L1 in FIG. 6) is relatively small, the increase in the capacitance value of the first capacitance element C1 becomes relatively small. On the other hand, the second displacement electrode substrate Ed2 moves away from the second fixed electrode substrate Ef2, and the inter-electrode distance between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases. As a result, the capacitance value of the second capacitance element C2 decreases. Since the distance in the X-axis direction between the center of the second displacement electrode substrate Ed2 and the central axis line CL (corresponding to L1 in FIG. 6) is relatively small, the amount of decrease in the capacitance value of the second capacitance element C2 becomes relatively small.

[0142] The second strain body 30B is elastically deformed in the same manner as the first strain body 30A to which the force Fz directed in the Z-axis direction positive side is applied as shown in FIG. 10A, and the capacitance value of the third capacitance element C3 decreases and the capacitance value of the fourth capacitance element C4 decreases. As described above, since the X-axis distance (corresponding to L2 in FIG. 6) between the center of the third displacement electrode substrate Ed3 and the central axis CL is relatively large, the displacement amount of the third displacement electrode substrate Ed3 in the direction away from the third fixed electrode substrate Ef3 is relatively large. Therefore, the decrease amount of the capacitance value of the third capacitance element C3 becomes relatively large. In addition, since the X-axis distance (corresponding to L3 in FIG. 3) between the center of the third displacement electrode substrate Ed3 and the center O of the force receiving body 20 is larger than the X-axis distance (corresponding to L1 in FIG. 6) between the center of the second displacement electrode substrate Ed2 and the center O of the force receiving body 20, the decrease amount of the capacitance value of the third capacitance element C3 becomes even larger. Similarly, the decrease amount of the capacitance value of the fourth capacitance element C4 becomes relatively large.

[0143] When viewed toward the Y-axis positive side, the third flexure body 30C has the first connection structure 31, the second connection structure 32, and the third connection structure 33 rotate clockwise. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the third flexure body 30C and the fixed body 25. Therefore, the fifth displacement electrode substrate Ed5 moves away from the fifth fixed electrode substrate Ef5, and the inter-electrode distance between the fifth displacement electrode substrate Ed5 and the sixth fixed electrode substrate Ef6 increases. Therefore, the capacitance value of the fifth capacitance element C5 decreases. Since the distance in the X-axis direction between the center of the fifth displacement electrode substrate Ed5 and the central axis line CL (corresponding to L1 in FIG. 6) is relatively small, the amount of decrease in the capacitance value of the fifth capacitance element C5 becomes relatively small. On the other hand, the sixth displacement electrode substrate Ed6 approaches the sixth fixed electrode substrate Ef6, and the inter-electrode distance between the sixth displacement electrode substrate Ed6 and the sixth fixed electrode substrate Ef6 decreases. As a result, the capacitance value of the sixth capacitance element C6 increases. Since the distance in the X-axis direction between the center of the sixth displacement electrode substrate Ed6 and the central axis line CL (corresponding to L1 in FIG. 6) is relatively small, the increase in the capacitance value of the sixth capacitance element C6 becomes relatively small.

[0144] The fourth flexure body 30D is elastically deformed in the same manner as the first flexure body 30A to which the force Fz directed toward the negative side in the Z-axis direction is applied as shown in FIG. 10B, and the capacitance value of the seventh capacitance element C7 increases, and the capacitance value of the eighth capacitance element C8 increases. As described above, since the X-axis distance (corresponding to L2 in FIG. 6) between the center of the seventh displacement electrode substrate Ed7 and the third connection structure portion 33 is relatively large, the displacement amount in the direction in which the seventh displacement electrode substrate Ed7 approaches the seventh fixed electrode substrate Ef7 is relatively large. Therefore, the increase in the capacitance value of the seventh capacitance element C7 becomes relatively large. In addition, since the X-axis distance (corresponding to L3 in FIG. 3) between the center of the seventh displacement electrode substrate Ed7 and the center O of the force receiving body 20 is larger than the X-axis distance (corresponding to L1 in FIG. 6) between the center of the sixth displacement electrode substrate Ed6 and the center O of the force receiving body 20, the increase in the capacitance value of the seventh capacitance element C7 becomes even larger. Similarly, the eighth capacitive element C8 also increases in capacitance value by a relatively large amount.

[0145] (When +Mz is applied) Next, a case will be described where a clockwise moment Mz (see FIG. 7) around the Z axis, i.e., toward the positive side in the Z axis direction, acts on force receiving body 20. In the following explanation as well, the symbols in the table of FIG. 12 are determined as described above according to the change in capacitance value.

[0146] In this case, the first flexure body 30A elastically deforms in the opposite direction to the first flexure body 30A shown in Fig. 8, and the capacitance value of the first capacitance element C1 decreases and the capacitance value of the second capacitance element C2 increases. In this case, since the distance in the X-axis direction between the center of the first displacement electrode substrate Ed1 and the central axis CL (corresponding to L1 in Fig. 6) is relatively small, the decrease in the capacitance value of the first capacitance element C1 becomes relatively small. Similarly, the increase in the capacitance value of the second capacitance element C2 becomes relatively small.

[0147] The second flexure body 30B elastically deforms in the opposite direction to the first flexure body 30A shown in Fig. 8, and the capacitance value of the third capacitance element C3 decreases and the capacitance value of the fourth capacitance element C4 increases. In this case, since the distance in the Y-axis direction between the center of the third displacement electrode substrate Ed3 and the central axis CL (corresponding to L1 in Fig. 6) is relatively small, the decrease in the capacitance value of the third capacitance element C3 becomes relatively small. Similarly, the increase in the capacitance value of the fourth capacitance element C4 becomes relatively small.

[0148] The third flexure body 30C elastically deforms in the opposite direction to the first flexure body 30A shown in Fig. 8, and the capacitance value of the fifth capacitance element C5 decreases and the capacitance value of the sixth capacitance element C6 increases. In this case, since the distance in the X-axis direction between the center of the fifth displacement electrode substrate Ed5 and the central axis CL (corresponding to L1 in Fig. 6) is relatively small, the decrease in the capacitance value of the fifth capacitance element C5 becomes relatively small. Similarly, the increase in the capacitance value of the sixth capacitance element C6 becomes relatively small.

[0149] The fourth flexure body 30D elastically deforms in the opposite direction to the first flexure body 30A shown in Fig. 8, and the capacitance value of the seventh capacitance element C7 decreases and the capacitance value of the eighth capacitance element C8 increases. In this case, since the distance in the Y-axis direction between the center of the seventh displacement electrode substrate Ed7 and the central axis CL (corresponding to L1 in Fig. 6) is relatively small, the decrease in the capacitance value of the seventh capacitance element C7 becomes relatively small. Similarly, the increase in the capacitance value of the eighth capacitance element C8 becomes relatively small.

[0150] In this manner, when a change in the capacitance value of each of capacitance elements C1-C8 is detected, the direction and magnitude of the force or moment acting on force receiving body 20 are detected. Then, as shown in FIG. 12, the capacitance value of each of capacitance elements C1-C8 changes.

[0151] From the table shown in FIG. 12, forces Fx, Fy, Fz and moments Mx, My, Mz acting on force receiving body 20 can be calculated by the following formulas. This makes it possible to detect six-axis components of force. In the following formulas, for convenience, the force or moment and the amount of change in capacitance value are connected with "=". However, since the force or moment and the capacitance value are different physical quantities, the force or moment is actually calculated by converting the amount of change in capacitance value. C1 to C8 in the following formulas indicate the amount of change in capacitance value in each capacitance element.

number

number

number

number

number

number

[0152] As described above, the force sensor 10 shown in FIG. 7 can detect forces Fx, Fy, Fz and moments Mx, My, Mz as shown in the above-mentioned formulas (4) to (9), and therefore can detect six-axis components of force. However, the number of axial components of force that the force sensor 10 can detect is not limited to six, and the number of axial components that can be detected is arbitrary depending on the number, structure, and shape of the strain bodies. The coefficients a1 to a24 included in the above-mentioned formulas (4) to (9) are coefficients that indicate that the amount of change (increase or decrease) in the capacitance value is relatively small. The coefficients a1 to a24 may be different from each other.

[0153] Since the coefficients a1 to a24 are included in the above-mentioned formulas (4) to (9), cross-axis sensitivity occurs in each axis component. However, even if cross-axis sensitivity occurs, a correction calculation can be performed by finding the inverse matrix of the cross-axis sensitivity matrix and multiplying the inverse matrix by the output (characteristic matrix) of the force sensor. As a result, the cross-axis sensitivity can be reduced to a level where the occurrence of the cross-axis sensitivity can be ignored.

[0154] Thus, according to this embodiment, when viewed in the Z-axis direction, the strain bodies 30A to 30D are disposed at different positions in the circumferential direction with respect to the center O of the force receiving body 20. When viewed in the Z-axis direction, the strain bodies 30A to 30D are disposed so that the second direction is along the direction from the center O of the force receiving body 20 toward the outside. This allows the outer dimensions of the force sensor 10 to be reduced when viewed in the Z-axis direction, and the force sensor 10 can be made smaller. For example, when the force receiving body 20 and the fixed body 25 are formed in a circular shape, the diameters of the force receiving body 20 and the fixed body 25 can be reduced. Also, for example, when the strain bodies 30A to 30D are disposed so that the second direction is along the direction perpendicular to the radial direction with respect to the center O of the force receiving body 20 (the direction corresponding to the circumferential direction), the diameters of the force receiving body 20 and the fixed body 25 can be increased. However, according to the present embodiment, since each of the strain bodies 30A to 30D is arranged so that the second direction is along the direction from the center O of the force receiving body 20 toward the outside, the external dimensions of the force sensor 10 can be reduced.

[0155] Furthermore, according to this embodiment, the displacement electrode substrate for the first flexure body 30A of the detection element 70 includes a first displacement electrode substrate Ed1 arranged on one side of the central axis CL of the first flexure body 30A in the X-axis direction, and a second displacement electrode substrate Ed2 arranged on the other side of the central axis CL. Similarly, the displacement electrode substrates for the second flexure body 30B to the fourth flexure body 30D include the third displacement electrode substrate Ed3 to the eighth displacement electrode substrate Ed8. This increases the number of detectable axial components, thereby improving the performance of the force sensor 10.

[0156] Furthermore, according to this embodiment, when viewed in the Z-axis direction, the second connection structure 32 of each of the flexure bodies 30A-30D is disposed at a position closer to the center O of the force receiving body 20 than the corresponding first connection structure 31. This allows each of the displacement electrode substrates Ed1-Ed8 to be disposed at a position closer to the center O of the force receiving body 20. Therefore, in the outer region of the force receiving body 20, a space can be secured between two adjacent flexure bodies 30A-30D, and a mechanism such as a stopper (not shown) for preventing damage to the force sensor 10 in the event of an overload can be disposed in this space. As a result, the force sensor 10 can be made smaller and its performance can be improved.

[0157] Furthermore, according to this embodiment, when viewed in the Z-axis direction, the second directions of the strain bodies 30A-30D are arranged radially with respect to the center O of the force receiving body 20. This allows the displacement electrode substrates Ed1-Ed8 of the detection element 70 to be evenly arranged in the circumferential direction with respect to the center O of the force receiving body 20. This allows the detection accuracy of the force or moment of each axial component to be improved, thereby enabling the force sensor 10 to have high performance.

[0158] Furthermore, according to this embodiment, the force receiving body 20 and the fixed body 25 are connected by the four strain bodies 30A to 30D. This allows the four strain bodies 30A to 30D to be arranged along the X-axis and Y-axis directions when viewed in the Z-axis direction. This allows the detection accuracy of the force or moment of each axial component to be improved, thereby improving the performance of the force sensor 10.

[0159] Furthermore, according to this embodiment, each of the displacement electrode substrates Ed1-Ed8 is connected to a surface of the 21st connection portion 37 extending from the force receiving body 20 toward the fixed body 25, the surface facing the fixed body 25. This makes it possible to easily position each of the displacement electrode substrates Ed1-Ed8 opposite the corresponding fixed electrode substrates Ef1-Ef8.

[0160] Furthermore, according to this embodiment, the displacement section 41 is connected to the surface of the second connection structure section 32 facing the fixed body 25, and the corresponding displacement electrode substrates Ed1 to Ed8 are connected to the surface of the displacement section 41 facing the fixed body 25. This allows each of the displacement electrode substrates Ed1 to Ed8 to be close to the corresponding fixed electrode substrates Ef1 to Ef8. This allows the detection sensitivity to be improved, and the force sensor 10 to have high performance.

[0161] Furthermore, according to this embodiment, the eleventh connection portion 34 of the first connection structure portion 31 and the twenty-first connection portion 37 of the second connection structure portion 32 extend in the Z-axis direction, and the twelfth connection portion 35 of the first connection structure portion 31 and the twenty-second connection portion 38 of the second connection structure portion 32 extend in the second direction (the X-axis direction or the Y-axis direction). As a result, when a force or moment acts on the force receiving body 20, the first connection structure portion 31 and the second connection structure portion 32 can elastically deform in any of the X-axis direction, the Y-axis direction, and the Z-axis direction. This allows the detection sensitivity of the force sensor 10 to be improved.

[0162] Furthermore, according to this embodiment, the distance L2 in the second direction between each of the displacement electrode substrates Ed1-Ed8 and the central axis CL of the corresponding strain body 30A-30D is greater than the distance L1 in the third direction between each of the displacement electrode substrates Ed1-Ed8 and the corresponding central axis CL. This makes it possible to increase the amount of change in the capacitance value of the corresponding capacitance element when the first connection structure 31, the second connection structure 32, and the third connection structure 33 rotate within a plane along the first and second directions. This makes it possible to improve the detection sensitivity and to achieve high performance of the force sensor 10.

[0163] In the above-described embodiment, the displacement electrode substrates Ed1 to Ed8 are connected to the displacement portion 41. However, the embodiment is not limited to this. For example, each of the flexure bodies 30A to 30D may not include the displacement portion 41. In this case, the displacement electrode substrates Ed1 to Ed8 may be connected to the surface of the 21st connection portion 37 of the corresponding second connection structure portion 32 facing the fixed body 25. Alternatively, the displacement electrode substrates Ed1 to Ed8 may be connected to the surface of the 22nd connection portion 38 of the corresponding second connection structure portion 32 facing the fixed body 25.

[0164] In the above-described embodiment, an example has been described in which the second connection structure 32 of each of the flexure bodies 30A to 30D is disposed closer to the center O of the force receiving body 20 than the corresponding first connection structure 31 when viewed in the Z-axis direction. However, the embodiment is not limited to this. For example, the first connection structure 31 of each of the flexure bodies 30A to 30D may be disposed closer to the center O of the force receiving body 20 than the corresponding second connection structure 32. Even in this case, the external dimensions of the force sensor 10 can be reduced by disposing each of the flexure bodies 30A to 30D such that the second direction is aligned with the direction from the center O of the force receiving body 20 toward the outside when viewed in the Z-axis direction.

[0165] In the above-described embodiment, an example has been described in which the capacitance element for the first flexure body 30A is composed of the first capacitance element C1 and the second capacitance element C2. However, the embodiment is not limited to this. For example, the capacitance element for the first flexure body 30A may be composed of one capacitance element. In this case, the capacitance element for the first flexure body 30A may be composed of one displacement electrode substrate and one fixed electrode substrate. The same applies to the capacitance element for the second flexure body 30B, the capacitance element for the third flexure body 30C, and the capacitance element for the fourth flexure body 30D.

[0166] In the above-described embodiment, an example has been described in which the first connection structure 31 includes the eleventh connection portion 34 and the twelfth connection portion 35. However, the structure of the first connection structure 31 is not limited to this and may be any structure. The same is true for the second connection structure 32.

[0167] In the above-described embodiment, an example has been described in which the X-axis direction distance L1 shown in Fig. 6 is greater than the Y-axis direction distance L2. However, the X-axis direction distance L1 may be equal to the Y-axis direction distance L2 or may be smaller than the Y-axis direction distance L2.

[0168] (Second embodiment) Next, a force sensor according to a second embodiment of the present invention will be described with reference to FIGS.

[0169] The second embodiment shown in Figs. 13 to 15 differs mainly in that the spring constant of the second connection structure is smaller than the spring constant of the first connection structure. Other configurations are substantially the same as those of the first embodiment shown in Figs. 1 to 12. In Figs. 13 to 15, the same parts as those of the first embodiment shown in Figs. 1 to 12 are given the same reference numerals and detailed description is omitted. Fig. 13 is a side view showing a first strain body of a force sensor according to the second embodiment. Fig. 14 is a plan view showing the first strain body of Fig. 13. Fig. 15 is a plan view showing a force sensor including the first strain body shown in Figs. 13 and 14 with the force receiving body omitted.

[0170] 13 and 14, in this embodiment, the spring constant of the second connection structure 32 of the first strain body 30A is smaller than the spring constant of the first connection structure 31. More specifically, the spring constant of the second connection structure 32 may be smaller than the spring constant of the first connection structure 31 with respect to each of a force acting in the X-axis direction, a force acting in the Y-axis direction, and a force acting in the Z-axis direction.

[0171] For example, the cross-sectional area of ​​the 21st connection portion 37 of the second connection structure portion 32 may be smaller than the cross-sectional area of ​​the 11th connection portion 34 of the first connection structure portion 31. In this case, the spring constant of the 21st connection portion 37 can be smaller than the spring constant of the 11th connection portion 34. The cross-sectional areas of the 21st connection portion 37 and the 11th connection portion 34 are cross-sectional areas along the XY plane. For example, the Y-axis dimension of the 21st connection portion 37 may be smaller than the Y-axis dimension of the 11th connection portion 34, and / or the X-axis dimension of the 21st connection portion 37 may be smaller than the X-axis dimension of the 11th connection portion 34. In this way, the spring constant of the second connection structure portion 32 can be smaller than the spring constant of the first connection structure portion 31 with respect to each of the forces in the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0172] For example, the cross-sectional area of ​​the 22nd connection portion 38 of the second connection structure portion 32 may be smaller than the cross-sectional area of ​​the 12th connection portion 35 of the first connection structure portion 31. In this case, the spring constant of the 22nd connection portion 38 can be smaller than the spring constant of the 12th connection portion 35. The cross-sectional areas of the 22nd connection portion 38 and the 12th connection portion 35 are cross-sectional areas along the XZ plane. For example, the Z-axis dimension of the 22nd connection portion 38 may be smaller than the Z-axis dimension of the 12th connection portion 35, and / or the X-axis dimension of the 22nd connection portion 38 may be smaller than the X-axis dimension of the 12th connection portion 35. In this way, the spring constant of the second connection structure portion 32 can be smaller than the spring constant of the first connection structure portion 31 with respect to each of the forces in the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0173] Similarly, the spring constant of the second connection structure 32 of the second flexure body 30B to the fourth flexure body 30D may also be smaller than the spring constant of the first connection structure 31.

[0174] 15, when viewed in the Z-axis direction, the four flexure bodies 30A-30D are arranged such that the second direction is along a direction from the center O of the force receiving body 20 toward the outside. The spring constant of the second connection structure 32 of each of the flexure bodies 30A-30D is smaller than the spring constant of the first connection structure 31, and the second connection structure 32 is arranged at a position closer to the center O of the force receiving body 20 than the first connection structure 31. This makes it possible to reduce the difference between the stress acting on the first connection structure 31 and the stress acting on the second connection structure 32 when a moment Mx about the X-axis, a moment My about the Y-axis, or a moment Mz about the Z-axis acts on the force receiving body 20. That is, if the spring constant of second connection structure part 32 is not smaller than the spring constant of first connection structure part 31, the stress acting on second connection structure part 32 due to moment Mx, My or Mz acting on force receiving body 20 may be larger than the stress acting on first connection structure part 31. This may increase the difference between the stress acting on first connection structure part 31 and the stress acting on second connection structure part 32. In contrast, according to the present embodiment, since the spring constant of second connection structure part 32 is smaller than the spring constant of first connection structure part 31, when moment Mx, My or Mz acts on force receiving body 20, it is possible to reduce the difference between the stress acting on first connection structure part 31 and the stress acting on second connection structure part 32.

[0175] As described above, according to the present embodiment, the spring constant of the second connection structure 32 is smaller than the spring constant of the first connection structure 31. This makes it possible to reduce the difference between the stress acting on the first connection structure 31 and the stress acting on the second connection structure 32. As a result, the stress acting on the first connection structure 31 and the stress acting on the second connection structure 32 can be equalized, thereby improving the reliability of the force sensor 10.

[0176] (Third embodiment) Next, a force sensor according to a third embodiment of the present invention will be described with reference to FIG.

[0177] The third embodiment shown in Fig. 16 differs mainly in that the displacement electrode substrate protrudes from the second connection structure toward the center of the force receiving body when viewed in the Z-axis direction. The other configurations are substantially the same as those of the first embodiment shown in Figs. 1 to 12. In Fig. 16, the same parts as those of the first embodiment shown in Figs. 1 to 12 are given the same reference numerals and detailed description will be omitted. Fig. 16 is a plan view showing a displacement electrode of a force sensor according to the third embodiment.

[0178] As shown in FIG. 16, the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 of the detection element 70 protrude from the second connection structure 32 of the first flexure body 30A toward the center O of the force receiving body 20 when viewed in the Z-axis direction. The displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 protrude from the second connection structure 32 to the negative side in the Y-axis direction. The first displacement electrode substrate Ed1 may protrude from the second connection structure 32 to the positive side in the X-axis direction, and the second displacement electrode substrate Ed2 may protrude from the second connection structure 32 to the negative side in the X-axis direction. The displacement electrode Ed of the first displacement electrode substrate Ed1 may be tapered toward the center O. This can prevent the first displacement electrode substrate Ed1 from interfering with the eighth displacement electrode substrate Ed8. Similarly, the displacement electrode Ed of the second displacement electrode substrate Ed2 may be tapered toward the center O. This makes it possible to prevent the second displacement electrode substrate Ed2 from interfering with the third displacement electrode substrate Ed3. The tips of the displacement electrodes Ed of the first displacement electrode substrate Ed1 and the tips of the displacement electrodes Ed of the second displacement electrode substrate Ed2 are disposed on the Y-axis direction positive side of the center O. In this way, it is possible to prevent the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 from interfering with the other displacement electrode substrates.

[0179] The displacement portion 41 may be attached to a common insulator IBdc of the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 using a bolt. A screw hole 42 into which the bolt is screwed may be formed in a surface of the displacement portion 41 facing the fixed body 25 (corresponding to the lower surface of the displacement portion 41 in FIG. 4). The displacement electrodes Ed of the first displacement electrode substrate Ed1 and the displacement electrodes Ed of the second displacement electrode substrate Ed2 may each be cut out so as not to overlap with the screw hole 42.

[0180] As shown in FIG. 16, the third displacement electrode substrate Ed3 and the fourth displacement electrode substrate Ed4 of the detection element 70 protrude from the second connection structure 32 of the second flexure body 30B toward the center O of the force receiving body 20 when viewed in the Z-axis direction. The displacement electrode Ed of the third displacement electrode substrate Ed3 and the displacement electrode Ed of the fourth displacement electrode substrate Ed4 protrude from the second connection structure 32 to the positive side in the X-axis direction. The third displacement electrode substrate Ed3 may protrude from the second connection structure 32 to the positive side in the Y-axis direction, and the fourth displacement electrode substrate Ed4 may protrude from the second connection structure 32 to the negative side in the Y-axis direction. The tip of the displacement electrode Ed of the third displacement electrode substrate Ed3 and the tip of the displacement electrode Ed of the fourth displacement electrode substrate Ed4 are disposed on the negative side in the X-axis direction from the center O. The third displacement electrode substrate Ed3 and the fourth displacement electrode substrate Ed4 are formed in the same manner as the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2. In this manner, the third displacement electrode substrate Ed3 and the fourth displacement electrode substrate Ed4 can be prevented from interfering with the other displacement electrode substrates.

[0181] As shown in FIG. 16, the fifth displacement electrode substrate Ed5 and the sixth displacement electrode substrate Ed6 of the detection element 70 protrude from the second connection structure 32 of the third flexure body 30C toward the center O of the force receiving body 20 when viewed in the Z-axis direction. The displacement electrode Ed of the fifth displacement electrode substrate Ed5 and the displacement electrode Ed of the sixth displacement electrode substrate Ed6 protrude from the second connection structure 32 to the positive side in the Y-axis direction. The fifth displacement electrode substrate Ed5 may protrude from the second connection structure 32 to the negative side in the X-axis direction, and the sixth displacement electrode substrate Ed6 may protrude from the second connection structure 32 to the positive side in the X-axis direction. The tip of the displacement electrode Ed of the fifth displacement electrode substrate Ed5 and the tip of the displacement electrode Ed of the sixth displacement electrode substrate Ed6 are disposed on the negative side in the Y-axis direction from the center O. The fifth displacement electrode substrate Ed5 and the sixth displacement electrode substrate Ed6 are formed in the same manner as the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2. In this way, it is possible to prevent the fifth displacement electrode substrate Ed5 and the sixth displacement electrode substrate Ed6 from interfering with the other displacement electrode substrates.

[0182] As shown in FIG. 16, the seventh displacement electrode substrate Ed7 and the eighth displacement electrode substrate Ed8 of the detection element 70 protrude from the second connection structure 32 of the fourth flexure body 30D toward the center O of the force receiving body 20 when viewed in the Z-axis direction. The displacement electrode Ed of the seventh displacement electrode substrate Ed7 and the displacement electrode Ed of the eighth displacement electrode substrate Ed8 protrude from the second connection structure 32 to the negative side in the X-axis direction. The seventh displacement electrode substrate Ed7 may protrude from the second connection structure 32 to the negative side in the Y-axis direction, and the eighth displacement electrode substrate Ed8 may protrude from the second connection structure 32 to the positive side in the Y-axis direction. The tip of the displacement electrode Ed of the seventh displacement electrode substrate Ed7 and the tip of the displacement electrode Ed of the eighth displacement electrode substrate Ed8 are disposed on the negative side in the Y-axis direction from the center O. The seventh displacement electrode substrate Ed7 and the eighth displacement electrode substrate Ed8 are formed in the same manner as the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2. In this way, it is possible to prevent the seventh displacement electrode substrate Ed7 and the eighth displacement electrode substrate Ed8 from interfering with the other displacement electrode substrates.

[0183] Thus, according to this embodiment, each of the displacement electrode substrates Ed1-Ed8 of the detection element 70 protrudes from the corresponding second connection structure portion 32 toward the center O of the force receiving body 20 when viewed in the Z-axis direction. This makes it possible to increase the planar area of ​​the displacement electrodes Ed of the displacement electrode substrates Ed1-Ed8, and to increase the electrostatic capacitance value of each of the capacitance elements C1-C8. This makes it possible to improve the detection sensitivity, and to achieve high performance of the force sensor 10.

[0184] (Fourth embodiment) Next, a force sensor according to a fourth embodiment of the present invention will be described with reference to FIG.

[0185] The fourth embodiment shown in Fig. 17 differs mainly in that the first connection structure includes a first buffer structure that buffers the force acting on the flexure body, and the second connection structure includes a second buffer structure that buffers the force acting on the flexure body. The other configurations are substantially the same as those of the second embodiment shown in Figs. 13 to 15. In Fig. 17, the same parts as those in the second embodiment shown in Figs. 13 to 15 are denoted by the same reference numerals and detailed description will be omitted. Fig. 17 is a side view showing a first flexure body of a force sensor according to the fourth embodiment.

[0186] 17, the first connection structure 31 of the first flexure body 30A according to the present embodiment may include a first buffer structure 43. The first buffer structure 43 is configured to buffer a force acting on the first flexure body 30A as a result of a force or moment acting on the force receiving body 20. One end of the first buffer structure 43 is connected to the eleventh connection portion 34, and the other end is connected to the twelfth connection portion 35. The first buffer structure 43 may be formed in a roughly rectangular shape when viewed in the X-axis direction.

[0187] A space 44 is formed between the first connection structure 31 and the second connection structure 32 of the first flexure body 30A shown in Fig. 17. The first buffer structure 43 may be formed so that the space 44 bulges out on the side opposite the second connection structure 32 in the Y-axis direction when viewed in the X-axis direction.

[0188] The space portion 44 may include a space main body portion 44a and a first bulging portion 44b. The space main body portion 44a is a space that is defined mainly by the eleventh connection portion 34 and the twelfth connection portion 35 of the first connection structure portion 31, the twenty-first connection portion 37 and the twenty-second connection portion 38 of the second connection structure portion 32, and the force receiving body 20.

[0189] The first bulging portion 44b is a space formed by the first buffer structure 43 so as to bulge from the space main body 44a. The first bulging portion 44b bulges from the space main body 44a to the negative side in the Y-axis direction. The space main body 44a and the first bulging portion 44b are in communication with each other, and the eleventh connecting portion 34 and the twelfth connecting portion 35 are separated. The first bulging portion 44b shown in FIG. 17 may be formed so that the first buffer structure 43 bulges toward the fixed body 25 in the Z-axis direction and bulges on the opposite side to the second connecting structure 32 in the Y-axis direction. The first bulging portion 44b bulges from the space main body 44a to the negative side in the Z-axis direction and to the negative side in the Y-axis direction.

[0190] 17 may include an eleventh buffer portion 45, a twelfth buffer portion 46, a thirteenth buffer portion 47, and a fourteenth buffer portion 48. The above-mentioned first bulge portion 44b is a space defined mainly by the eleventh buffer portion 45, the twelfth buffer portion 46, the thirteenth buffer portion 47, and the fourteenth buffer portion 48.

[0191] The eleventh buffer section 45 may extend from the end of the eleventh connecting section 34 on the negative side in the Z axis direction to the positive side in the Y axis direction. The eleventh buffer section 45 may extend in the Y axis direction. The twelfth buffer section 46 may extend from the end of the eleventh buffer section 45 on the negative side in the Y axis direction to the negative side in the Z axis direction. The twelfth buffer section 46 may extend in the Z axis direction. The thirteenth buffer section 47 may extend from the end of the twelfth buffer section 46 on the negative side in the Z axis direction to the positive side in the Y axis direction. The thirteenth buffer section 47 may extend in the Y axis direction. The fourteenth buffer section 48 may extend from the end of the thirteenth buffer section 47 on the positive side in the Y axis direction to the positive side in the Z axis direction. The fourteenth buffer section 48 may extend in the Z axis direction. The fourteenth buffer section 48 may be connected to the end of the twelfth connecting section 35 on the negative side in the Y axis direction.

[0192] 17, the second connection structure 32 of the first flexure body 30A according to this embodiment may include a second buffer structure 49. The second buffer structure 49 is configured to buffer a force acting on the first flexure body 30A as a result of a force or moment acting on the force receiving body 20. One end of the second buffer structure 49 is connected to the 21st connection portion 37, and the other end is connected to the 22nd connection portion 38. The second buffer structure 49 may be formed in a rectangular shape when viewed in the X-axis direction.

[0193] When viewed in the X-axis direction, the above-mentioned space 44 may have a second buffer structure 49 formed therein so as to bulge out in the Y-axis direction opposite to the first connection structure 31.

[0194] The above-described space portion 44 according to the present embodiment may further include a second bulging portion 44c. The second bulging portion 44c is a space formed by the second buffer structure 49 so as to bulge from the space main body portion 44a. The second bulging portion 44c bulges from the space main body portion 44a to the positive side in the Y-axis direction. The space main body portion 44a and the second bulging portion 44c are in communication with each other, and the 21st connecting portion 37 and the 22nd connecting portion 38 of the second connecting structure portion 32 are separated from each other.

[0195] 17 may include a 21st buffer portion 50, a 22nd buffer portion 51, and a 23rd buffer portion 52. The above-mentioned second bulge portion 44c is a space defined mainly by the 21st buffer portion 50, the 22nd buffer portion 51, and the 23rd buffer portion 52.

[0196] The 21st buffer section 50 may extend from the end of the 21st connecting section 37 on the negative side in the Z-axis direction to the negative side in the Y-axis direction. The 21st buffer section 50 may extend in the Y-axis direction. The 22nd buffer section 51 may extend from the end of the 21st buffer section 50 on the negative side in the Y-axis direction to the negative side in the Z-axis direction. The 22nd buffer section 51 may extend in the Z-axis direction. The 23rd buffer section 52 may extend from the end of the 22nd buffer section 51 on the negative side in the Z-axis direction to the positive side in the Y-axis direction. The 23rd buffer section 52 may extend in the Y-axis direction. The 23rd buffer section 52 may be connected to the end of the 22nd connecting section 38 on the negative side in the Y-axis direction. The 23rd buffer section 52 may be formed in a continuous line with the 22nd connecting section 38 along the Y-axis direction. The 23rd buffer section 52 is a portion that defines the second bulging section 44c described above, and the 22nd connecting section 38 is a portion that defines the space main body section 44a described above.

[0197] 17, the displacement portion 41 may be connected to the second buffer structure 49. More specifically, the displacement portion 41 may be connected to the 22nd buffer portion 51 of the second buffer structure 49. The displacement portion 41 may be connected to a surface of the 22nd buffer portion 51 facing the fixed body 25 (the lower surface of the 22nd buffer portion 51 in FIG. 17). A part of the displacement portion 41 may be connected to a surface of the 23rd buffer portion 52 facing the fixed body 25.

[0198] The spring constant of the third connection structure 33 of the first strain body 30A according to the present embodiment may be greater than the spring constant of the first connection structure 31 and the spring constant of the second connection structure 32. The spring constant of the third connection structure 33 may be greater than the spring constant of the first connection structure 31 and the spring constant of the second connection structure 32 with respect to each of a force acting in the X-axis direction, a force acting in the Y-axis direction, and a force acting in the Z-axis direction.

[0199] 13 and 14, the spring constant of the second connection structure part 32 of the first flexure body 30A according to the present embodiment may be smaller than the spring constant of the first connection structure part 31. The cross-sectional area of ​​the twenty-first connection part 37 may be smaller than the cross-sectional area of ​​the eleventh connection part 34. The cross-sectional area of ​​the twenty-second connection part 38 may be smaller than the cross-sectional area of ​​the twelfth connection part 35.

[0200] The spring constant of the second buffer structure 49 may be smaller than the spring constant of the first buffer structure 43. For example, the cross-sectional area of ​​each of the buffer sections 50-52 of the second buffer structure 49 may be smaller than the cross-sectional area of ​​each of the buffer sections 45-48 of the first buffer structure 43. For example, the second buffer structure 49 may have a shape such that the spring constant of the second buffer structure 49 is smaller than the spring constant of the first buffer structure 43 when viewed in the X-axis direction.

[0201] As shown in FIG. 17, the first strain generating body 30A may further include a first seat 53 and a second seat 54. The first seat 53 is interposed between the force receiving body 20 and the first connection structure 31. The first connection structure 31 is connected to the force receiving body 20 via the first seat 53. The second seat 54 is interposed between the force receiving body 20 and the second connection structure 32. The second connection structure 32 is connected to the force receiving body 20 via the second seat 54. The first seat 53 and the second seat 54 may each have a relatively high rigidity. The first seat 53 may be formed separately from the first connection structure 31, or may be formed integrally with the first connection structure 31 using a continuous material. The second seat 54 may be formed separately from the second connection structure 32, or may be formed integrally with the second connection structure 32 using a continuous material.

[0202] The second flexure body 30B to the fourth flexure body 30D have the same configuration as the first flexure body 30A.

[0203] When a force or moment acts on the force sensor 10 according to this embodiment, the first connection structure 31 and the second connection structure 32 elastically deform. At this time, the first buffer structure 43 absorbs and buffers the force acting on the first connection structure 31. This makes it possible to reduce the stress acting on the first connection structure 31. Similarly, the second buffer structure 49 absorbs and buffers the force acting on the second connection structure 32. This makes it possible to reduce the stress acting on the second connection structure 32.

[0204] When a force or moment acts on the force sensor 10 according to this embodiment, the third connection structure 33 does not substantially elastically deform because the spring constant of the third connection structure 33 is large. However, the eleventh buffer section 45 and the thirteenth buffer section 47 of the first buffer structure 43 extend in the Y-axis direction, and the twelfth buffer section 46 and the fourteenth buffer section 48 extend in the Z-axis direction. As a result, even when a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a force Fz in the Z-axis direction act on the force receiving body 20, the first buffer structure 43 can elastically deform and displace the displacement section 41. Even when a moment Mx about the X-axis, a moment My about the Y-axis, and a moment Mz about the Z-axis act on the force receiving body 20, the displacement section 41 can be displaced in the same manner.

[0205] Similarly, the 21st buffer portion 50 and the 23rd buffer portion 52 of the second buffer structure 49 extend in the Y-axis direction, and the 22nd buffer portion 51 extends in the Z-axis direction. As a result, even if a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a force Fz in the Z-axis direction act on the force receiving body 20, the second buffer structure 49 can elastically deform and displace the displacement portion 41. Even if a moment Mx about the X-axis, a moment My about the Y-axis, and a moment Mz about the Z-axis act on the force receiving body 20, the displacement portion 41 can be displaced in the same manner.

[0206] The change in capacitance value of capacitance elements C1 to C8 when a force or moment of each axial component acts on force receiving body 20 is similar to that shown in the table of Fig. 12. A detailed description will be omitted here.

[0207] As described above, according to the present embodiment, the first connection structure 31 of each of the flexure bodies 30A to 30D includes the first buffer structure 43 that buffers the force acting on the flexure bodies 30A to 30D. This reduces the stress acting on the first connection structure 31. This improves the reliability of the force sensor 10. Furthermore, the height dimension (dimension in the Z-axis direction) of the force sensor 10 can be reduced, allowing the force sensor 10 to be made low-profile.

[0208] According to this embodiment, the first buffer structure 43 is formed so that the space 44 bulges out on the opposite side of the second connection structure 32 of the first flexure body 30A in the Y-axis direction when viewed in the X-axis direction. The first buffer structure 43 is also formed for the second flexure body 30B to the fourth flexure body 30D. This can enhance the force buffering effect of the first buffer structure 43 for each of the flexure bodies 30A to 30D. This can further improve the reliability and sensitivity of the force sensor 10. For example, when the first buffer structure 43 extends relatively long in the Y-axis direction as shown in FIG. 17, the displacement part 41 can be easily displaced by the force and moment while reducing the height dimension of the force sensor 10. This can reduce the height of the force sensor 10 and improve the sensitivity of the force sensor 10.

[0209] Furthermore, according to this embodiment, when viewed in the X-axis direction, the first buffer structure 43 is formed so as to bulge in the Z-axis direction toward the fixed body 25 and bulge in the Y-axis direction to the opposite side of the second connection structure 32 of the first flexure body 30A. The first buffer structures 43 are similarly formed for the second flexure body 30B to the fourth flexure body 30D. This can enhance the force buffering effect of the first buffer structure 43 for each of the flexure bodies 30A to 30D. This can further improve the reliability and sensitivity of the force sensor 10.

[0210] Furthermore, according to this embodiment, the second connection structure 32 of each of the flexure bodies 30A-30D includes a second buffer structure 49 that buffers the force acting on the flexure bodies 30A-30D. This reduces the stress acting on the second connection structure 32. This improves the reliability and sensitivity of the force sensor 10. Furthermore, the height dimension of the force sensor 10 can be reduced, allowing the force sensor 10 to have a low profile.

[0211] According to this embodiment, the second buffer structure 49 is formed so that the space 44 bulges out on the opposite side to the first connection structure 31 in the Y-axis direction when viewed in the X-axis direction. The second buffer structure 49 is also formed for the second flexure body 30B to the fourth flexure body 30D. This can enhance the force buffering effect of the second buffer structure 49 for each of the flexure bodies 30A to 30D. This can further improve the reliability and sensitivity of the force sensor 10. For example, when the second buffer structure 49 extends relatively long in the Y-axis direction as shown in FIG. 17, the displacement portion 41 can be easily displaced by the force and moment while reducing the height dimension of the force sensor 10. This can reduce the height of the force sensor 10 and improve the sensitivity of the force sensor 10.

[0212] Furthermore, according to this embodiment, the spring constant of the third connection structure 33 of each of the strain bodies 30A to 30D is greater than the spring constant of the first connection structure 31 and the spring constant of the second connection structure 32. This makes it possible to increase the stress acting on the third connection structure 33. In this case, it is possible to reduce the stress acting on the first connection structure 31 and the stress acting on the second connection structure 32. This makes it possible to improve the reliability and sensitivity of the force sensor 10. Furthermore, it is possible to reduce the height dimension of the force sensor 10, thereby making it possible to reduce the height of the force sensor 10.

[0213] In the above-described embodiment, the first buffer structure 43 is formed such that the space 44 bulges out on the opposite side to the second connection structure 32 in the Y-axis direction when viewed in the X-axis direction. However, the first buffer structure 43 may be formed in any shape as long as it can buffer the force acting on the corresponding strain bodies 30A to 30D. The same applies to the second buffer structure 49.

[0214] The present invention is not limited to the above-mentioned embodiment and modified examples, and the components can be modified and embodied in the implementation stage without departing from the gist of the invention. In addition, various inventions can be formed by appropriate combinations of multiple components disclosed in the above-mentioned embodiment and modified examples. Some components may be deleted from all the components shown in the embodiment and modified examples. Furthermore, components from different embodiments and modified examples may be appropriately combined. [Explanation of symbols]

[0215] 10 Force sensor 20 Receptive body 25 Fixed body 31 First connecting structure 32 Second connection structure part 33 Third connecting structure 34 11th Junction 35 12th Connection 36 First connection end 37 21st Junction 38 22nd Connection 39 Second connection end 40 Third connection end 41 Displacement section 43 First buffer structure 44 Space section 49 Second buffer structure CL center axis

Claims

1. a first sensor body that receives the force or moment to be detected; A second sensor body disposed at a position different from the first sensor body in the first direction; a plurality of strain bodies that connect the first sensor body and the second sensor body and are elastically deformed by the action of a force or moment applied to the first sensor body; a detection element that detects a change in capacitance value based on a displacement caused by elastic deformation of the strain body; a detection circuit that outputs an electrical signal indicative of a force or moment acting on the first sensor body based on a detection result of the detection element; Equipped with the strain body includes a first connection structure connected to the first sensor body, a second connection structure connected to the first sensor body, the second connection structure being arranged at a position different from the first connection structure in a second direction perpendicular to the first direction, and a third connection structure connecting the first connection structure and the second connection structure to the second sensor body, the third connection structure being arranged between the first connection structure and the second connection structure in the second direction, the detection element includes a fixed electrode substrate provided on the second sensor body, and a displacement electrode substrate opposed to the fixed electrode substrate and displaced together with the second connection structure portion, When viewed in the first direction, each of the strain bodies is disposed at a different position in a circumferential direction with respect to a center of the first sensor body, The strain generating body is disposed so that the second direction is along a direction from the center of the first sensor body toward an outside. Force sensor.

2. The displacement electrode substrate includes a one-side displacement electrode substrate arranged on one side with respect to a central axis of the strain body, and an other-side displacement electrode substrate arranged on the other side with respect to the central axis in a third direction perpendicular to each of the first direction and the second direction. The force sensor according to claim 1 .

3. When viewed in the first direction, the second connection structure of each of the strain bodies is disposed at a position closer to the center of the first sensor body than the corresponding first connection structure. The force sensor according to claim 1 .

4. When viewed in the first direction, the second direction of each of the strain bodies is radially disposed with respect to the center of the first sensor body. The force sensor according to claim 1 .

5. The first sensor body and the second sensor body are connected by four of the strain bodies. The force sensor according to claim 4.

6. the second connection structure portion includes a 21st connection portion extending from the first sensor body toward the second sensor body, and a 22nd connection portion connecting the third connection structure portion and the 21st connection portion, the one-side displacement electrode substrate and the other-side displacement electrode substrate are connected to a surface of the 21st connection portion facing the second sensor body; The force sensor according to claim 2 .

7. the strain body includes a displacement portion connected to a surface of the second connection structure portion facing the second sensor body, the one-side displacement electrode substrate and the other-side displacement electrode substrate are connected to a surface of the displacement portion facing the second sensor body; The force sensor according to claim 2 .

8. the first connection structure portion includes an eleventh connection portion extending from the first sensor body toward the second sensor body, and a twelfth connection portion connecting the third connection structure portion and the eleventh connection portion, the second connection structure portion includes a 21st connection portion extending from the first sensor body toward the second sensor body, and a 22nd connection portion connecting the third connection structure portion and the 21st connection portion, The eleventh connection portion and the twenty-first connection portion extend in the first direction, The twelfth connection portion and the twenty-second connection portion extend in the second direction. The force sensor according to claim 1 .

9. a distance in the second direction between the one-side displacement electrode substrate and the central axis of the strain body is greater than a distance in the third direction between the one-side displacement electrode substrate and the central axis of the strain body; The force sensor according to claim 2 .

10. The spring constant of the second connection structure is smaller than the spring constant of the first connection structure. The force sensor according to claim 1 .

11. the one-side displacement electrode substrate and the other-side displacement electrode substrate protrude from the second connection structure portion toward the center of the first sensor body when viewed in the first direction; The force sensor according to claim 2 .

12. The first connection structure includes a first buffer structure that buffers a force acting on the strain body. The force sensor according to claim 1 .

13. a space is formed between the first connection structure and the second connection structure, the first buffer structure is formed such that, when viewed in a third direction perpendicular to each of the first direction and the second direction, the space bulges out toward an opposite side to the second connection structure in the second direction; The force sensor according to claim 12.

14. the first buffer structure is formed such that, when viewed in the third direction, the space bulges toward the second sensor body in the first direction and bulges toward an opposite side to the second connection structure in the second direction. The force sensor according to claim 13.

15. The second connection structure includes a second buffer structure that buffers a force acting on the strain body. The force sensor according to claim 1 .

16. a space is formed between the first connection structure and the second connection structure, the second buffer structure is formed such that, when viewed in a third direction perpendicular to each of the first direction and the second direction, the space bulges out toward an opposite side to the first connection structure in the second direction; The force sensor according to claim 15.

17. a spring constant of the third connection structure portion is greater than a spring constant of the first connection structure portion and a spring constant of the second connection structure portion; The force sensor according to claim 1 .

Images