Capacitive sensor

Abstract

A capacitance-type sensor detects a force acting in at least one of a first direction, a second direction, and a third direction on the basis of a change in capacitance of an electrode unit comprising a first comb structure and a second comb structure facing the first comb structure, the second direction intersecting the first direction, and the third direction intersecting the first direction. A capacitance-type sensor is provided with: a first substrate layer (40) having a boss section (40A) for receiving a force acting in at least one direction, the third direction being the thickness direction, the first substrate layer (40) being deflected and deformed on the basis of the force acting on the boss section (40A), and a second substrate layer (40) which is deflected and deformed on the basis of the force acting on the boss section (40A), the third direction being the thickness direction of the first substrate layer (40) and the third direction being the thickness direction of the second substrate layer (40); and a second substrate layer (30) having a third direction as a thickness direction, the second substrate layer (30) having a mass part (60), a movable electrode, and a fixed electrode, force acting in at least one direction being transmitted from the boss part (40A) to the mass part (60), the movable electrode having a first comb structure and being displaced in conjunction with the mass part (60), and the fixed electrode having a second comb structure.

Description

Technical Field

[0001] This invention relates to electrostatic capacitive sensors. Background Technology

[0002] Capacitive sensors detect inertia, pressure, etc., based on changes in electrostatic capacitance corresponding to changes in the gap between the substrate layer and the device layer. For example, the substrate layer has electrodes, and the device layer has a movable part, a support part, and a spring part. The support part supports the movable part, and the spring part elastically connects the movable part to the support part. Capacitive sensors are manufactured, for example, using MEMS (Micro Electro Mechanical Systems) technology.

[0003] For example, Patent Document 1 discloses the following technology: the tilting motion of a seesaw electrode that detects the change in direction of the force acting on the upper surface of the protrusion, and the force acting on the upper surface of the protrusion in the X, Y, and Z axis directions is calculated based on the detected quantity.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-152578 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, in the device described in Patent Document 1, in order to improve the detection sensitivity of the tilting motion of the seesaw electrode, it is necessary to reduce the thickness of the thin film portion that is provided in a manner that surrounds the protrusion. This results in problems such as increased influence of process deviations and reduced mechanical strength of the thin film portion.

[0009] The present invention was made in view of the following circumstances, and its object is to provide an electrostatic capacitive sensor that can improve the detection sensitivity of externally applied forces while ensuring mechanical strength.

[0010] Solution for solving the problem

[0011] An electrostatic capacitive sensor of one aspect of the present invention detects a force acting in at least one of a first direction, a second direction, and a third direction based on the change in electrostatic capacitance of an electrode unit consisting of a first comb structure and a second comb structure opposite to the first comb structure. The second direction intersects the first direction, and the third direction intersects both the first and second directions. The electrostatic capacitive sensor comprises: a first substrate layer having a boss portion that receives a force acting in at least one direction, with the third direction as its thickness direction; and a second substrate layer having a mass portion, a movable electrode, and a fixed electrode, with the third direction as its thickness direction, wherein the force acting in at least one direction is transmitted from the boss portion to the mass portion, the movable electrode having a first comb structure and moving in conjunction with the mass portion, and the fixed electrode having a second comb structure.

[0012] The effects of the invention

[0013] According to the present invention, the sensitivity to detecting externally applied forces can be improved while ensuring mechanical strength. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view of the electrostatic capacitive sensor according to the first embodiment.

[0015] Figure 2 This is a top view of the device layer.

[0016] Figure 3 This is a top view of the first electrode unit.

[0017] Figure 4 This is a diagram used to illustrate the outline of the electrode structure.

[0018] Figure 5 This is a diagram used to illustrate the outline of the electrode structure.

[0019] Figure 6 This is a diagram used to illustrate the outline of the electrode structure.

[0020] Figure 7 This is a diagram used to illustrate the characteristics of the first electrode unit in the first embodiment.

[0021] Figure 8 This is a top view of the third electrode unit in the first embodiment.

[0022] Figure 9 This is a diagram used to illustrate the characteristics of the third electrode unit in the first embodiment.

[0023] Figure 10 This is a top view of the third electrode unit in the second embodiment.

[0024] Figure 11This is a diagram used to illustrate the characteristics of the third electrode unit in the second embodiment.

[0025] Figure 12 This is a top view of the first electrode unit in another embodiment.

[0026] Figure 13 This is a top view of the first electrode unit in another embodiment.

[0027] Figure 14 This is a top view of the first electrode unit in another embodiment. Detailed Implementation

[0028] <First Embodiment>

[0029] Hereinafter, the electrostatic capacitive sensor 10 of the first embodiment will be described with reference to the accompanying drawings. The accompanying drawings of the embodiment are illustrative, and the dimensions and shapes of the parts are schematic; they should not be interpreted as limiting the scope of protection of the present invention to this embodiment.

[0030] The following describes the structure of the electrostatic capacitive sensor 10. In the various figures, to clarify the relationship between the figures and facilitate understanding of the positional relationships of the components, an orthogonal coordinate system consisting of the X-axis, Y-axis, and Z-axis is sometimes used for convenience. Directions parallel to the X-axis, Y-axis, and Z-axis are designated as the X-axis direction, Y-axis direction, and Z-axis direction, respectively. The surface defined by the X-axis and Y-axis is designated as the XY plane. Furthermore, for convenience, the positive Z-axis direction (the direction of the arrow) is designated as "up" or "above," and the negative Z-axis direction (opposite to the direction of the arrow) is designated as "down" or "below," but the orientation of the electrostatic capacitive sensor is not limited to this.

[0031] The electrostatic capacitive sensor 10 is a type of force sensor that detects forces acting in at least one of the X-axis, Y-axis, and Z-axis directions based on changes in the electrostatic capacitance of an electrode unit. For example... Figure 1As shown, the electrostatic capacitive sensor 10 includes a lower cover 20, a device layer 30, and an upper cover 40. The lower cover 20, device layer 30, and upper cover 40 are stacked sequentially along the Z-axis direction. Hereinafter, the Z-axis direction in which the lower cover 20, device layer 30, and upper cover 40 are stacked is defined as the "thickness direction". The device layer 30 is bonded to the lower cover 20 to form a MEMS substrate 50. The upper cover 40 is bonded to the device layer 30 of the MEMS substrate 50. In other words, the upper cover 40 is bonded to the lower cover 20 via the device layer 30. The lower cover 20 and the upper cover 40 are opposite each other in the thickness direction, separated by the device layer 30. The lower cover 20 and the upper cover 40 constitute an encapsulation structure that forms a vibration space inside for the device layer 30 to vibrate. Furthermore, a boss portion 40A protruding from the upper cover 40 along the thickness direction is provided on the upper cover 40. The boss portion 40A has a first portion protruding upward from the upper cover 40 and a second portion protruding downward from the upper cover 40. The first portion of the boss portion 40A receives forces acting from the outside of the capacitive sensor 10 along the X-axis, Y-axis, and Z-axis directions. The second portion of the boss portion 40A, when viewed from above, is located at the center of the upper cover 40 (the lower portion of the boss portion 40A), with its end abutting against the device layer 30. The upper cover 40 has a thin-film (diaphragm) structure. By applying force to the first portion of the boss portion 40A, it tilts and twists, and the second portion of the boss portion 40A shifts in the opposite direction to the force applied to the first portion of the boss portion 40A, transmitting the force acting on the boss portion 40A from the outside of the capacitive sensor 10 to the device layer 30. The upper cover 40 is an example of a first substrate layer that flexes and deforms based on the force acting on the boss portion 40A.

[0032] like Figure 2 As shown, the device layer 30 includes a mass portion 60, a first electrode unit 70, a second electrode unit 80, and a third electrode unit 90. A spacer S1 is sandwiched between the device layer 30 and the upper cover 40, and a spacer S2 is sandwiched between the device layer 30 and the lower cover 20, thereby ensuring movable regions between the device layer 30 and the upper cover 40 and between the device layer 30 and the lower cover 20 for the device layer 30 to move in the X-axis, Y-axis, and Z-axis directions based on the force transmitted from the boss portion 40A. The device layer 30 corresponds to an example of a second substrate layer.

[0033] When viewed from above, the mass unit 60 is located at the center of the device layer 30, and the force is transmitted from the boss portion 40A of the upper cover 40 to the mass unit 60.

[0034] Four first beams 100 extending along the X-axis are provided between the mass section 60 and the electrode holding section 91 of the third electrode unit 90. Each first beam 100 includes a first unit 100A connected to the edge of the mass section 60 in the X-axis direction via a spring D1, and a second unit 100B connected to the first unit 100A via a spring D2. Spring D1, an example of a third elastic part, connects the mass section 60 and the first unit 100A in a manner that restricts displacement in the X-axis and Y-axis directions while allowing rotation centered on the Y-axis, which extends in the XY plane along the X-axis and Y-axis directions. Spring D2, an example of a first elastic part, connects the first unit 100A and the second unit 100B in a manner that restricts displacement in the X-axis direction while allowing displacement in the Y-axis direction. The second unit 100B is held in the lower cover 20 via a spring D3. One end of spring D3 is connected to the second unit 100B, and the other end is connected to the lower cover 20. Spring D3 connects the second unit 100B and the lower cover 20 in a manner that allows displacement in the X-axis direction and allows rotation about the Y-axis as the axis of rotation while limiting displacement in the Y-axis direction.

[0035] Two second beams 110 extending along the Y-axis are provided between the mass section 60 and the electrode holding section 91 of the third electrode unit 90. Each second beam 110 includes a first unit 110A connected to the edge of the mass section 60 in the Y-axis direction via a spring D4, and a second unit 110B connected to the first unit 110A via a spring D5. Spring D4 is an example of a third elastic part, connecting the mass section 60 and the first unit 110A in a manner that restricts displacement in the X-axis and Y-axis directions while allowing rotation centered on the X-axis, which extends in the XY plane along the X-axis and Y-axis directions. Spring D5 is an example of a second elastic part, connecting the first unit 110A and the second unit 110B in a manner that restricts displacement in the Y-axis direction while allowing displacement in the X-axis direction.

[0036] Adjacent electrode units in the first electrode unit 70, which is positioned on both sides of the mass unit 60 in the X-axis direction, and the second electrode unit 80, which is positioned on both sides of the mass unit 60 in the Y-axis direction, are connected to each other via a spring D6. The spring D6 is an example of a connecting part that allows displacement of adjacent electrode units in each translational direction in the X-axis and Y-axis directions, and correlates the displacements of adjacent electrode units in the X-axis and Y-axis directions.

[0037] Next, the structure of the first electrode unit 70 will be described. Furthermore, the first electrode unit 70, located on both sides of the mass portion 60 in the X-axis direction, and the second electrode unit 80, located on both sides of the mass portion 60 in the Y-axis direction, have substantially the same structure as the first electrode unit 70. Therefore, in the following description, the first electrode unit 70 located on one side of the mass portion 60 in the X-axis direction (the negative direction side of the X-axis direction) will be used as an example, and the description of the first electrode unit 70 located on the other side of the mass portion 60 in the X-axis direction (the positive direction side of the X-axis direction) and the second electrode units 80 located on both sides of the mass portion 60 in the Y-axis direction will be omitted.

[0038] like Figure 3 As shown, the first electrode unit 70 is disposed on both sides of the mass part 60 in the X-axis direction, and includes an electrode holding part 71 connected to the two first beam parts 100 respectively via a spring D7, a movable electrode 72 held in the electrode holding part 71, and a fixed electrode 73 disposed opposite to the movable electrode 72. The fixed electrode 73 is held by an electrode holding part 74 fixed to the device layer 30. The spring D7 is an example of a third elastic part, which connects the second unit 100B of the first beam part 100 to the electrode holding part 91 in a manner that limits displacement in the X-axis and Y-axis directions and allows rotation centered on the Y-axis extending in the XY plane along the X-axis and Y-axis directions. The fixed electrode 73 has a second comb tooth structure including a plurality of flat plate electrodes extending parallel to the X-axis direction as comb teeth. The movable electrode 72 has a first comb tooth structure including a plurality of flat plate electrodes extending along the X-axis direction as comb teeth. The spacing between the teeth of the movable electrode 72 and the fixed electrode 73 is set to the same interval, and the teeth of the movable electrode 72 and the fixed electrode 73 are alternately arranged at intervals in the Y-axis direction. The electrode holding part 71 is held to the lower cover 20 by four springs 75. One end of each of the four springs 75 is connected to the electrode holding part 71, and the other end is connected to the lower cover 20. The four springs 75 connect the electrode holding part 71 to the lower cover 20 in a manner that allows displacement in the X-axis direction and restricts displacement in the Y-axis direction. This allows translational movement of the electrode holding part 71 in the X-axis direction.

[0039] Furthermore, when the mass unit 60 shifts in the X-axis direction, the driving force generated by the shift of the mass unit 60 is transmitted to the second unit 100B of the first beam unit 100 via spring D1, the first unit 100A of the first beam unit 100, and spring D2, thereby causing the second unit 100B of the first beam unit 100 to shift in the X-axis direction. Additionally, the driving force generated by the shift of the second unit 100B of the first beam unit 100 is transmitted to the electrode holding unit 71 via spring D7. As the electrode holding unit 71 shifts in the X-axis direction, the relative area of ​​the comb teeth of the movable electrode 72 and the comb teeth of the fixed electrode 73 changes in the Y-axis direction, thereby changing the electrostatic capacitance between the movable electrode 72 and the fixed electrode 73. Furthermore, by outputting a potential signal representing this change in electrostatic capacitance from the movable electrode 72 and the fixed electrode 73 to an external controller, the displacement of the mass unit 60 in the X-axis direction is detected.

[0040] Specifically, such as Figure 4 As shown, when the comb teeth of the movable electrode 72 and the comb teeth of the fixed electrode 73 extend along the X-axis direction, the change in electrostatic capacitance ΔC between the movable electrode 72 and the fixed electrode 73 is represented by the following equation (1). In this example, as the movable electrode 72 shifts in the X-axis direction, the relative area of ​​the comb teeth of the movable electrode 72 and the comb teeth of the fixed electrode 73 changes in the Y-axis direction.

[0041] [Formula 1]

[0042]

[0043] Where Δx represents the displacement of the movable electrode 72 in the X-axis direction, ε represents the dielectric constant, h represents the thickness of the movable electrode 72, d represents the gap between the movable electrode 72 and the fixed electrode 73, L represents the length of the relative portion of the comb teeth, and N represents the number of comb teeth.

[0044] In addition, such as Figure 5 As shown, the comb teeth of the movable electrode 72 and the comb teeth of the fixed electrode 73 can also extend along the Y-axis direction. In this case, the change in electrostatic capacitance ΔC between the movable electrode 72 and the fixed electrode 73 is represented by the following equation (2). In this example, even if the movable electrode 72 is displaced in the X-axis direction, the relative area of ​​the comb teeth of the movable electrode 72 and the comb teeth of the fixed electrode 73 in the Y-axis direction does not change.

[0045] [Formula 2]

[0046]

[0047] Where Δx represents the displacement of the movable electrode 72 in the X-axis direction, ε represents the dielectric constant, h represents the thickness of the movable electrode 72, d represents the gap between the movable electrode 72 and the fixed electrode 73, L represents the length of the relative portion of the comb teeth, and N represents the number of comb teeth.

[0048] In addition, such as Figure 6 As shown, the movable electrode 72 and the fixed electrode 73 can also use the electrode portion extending along the Y-axis as the main trunk, and have multiple electrode portions extending along the X-axis as comb teeth extending from the main trunk. In this case, the change in electrostatic capacitance ΔC between the movable electrode 72 and the fixed electrode 73 is represented by the following equation (3). In this example, as the movable electrode 72 shifts in the X-axis direction, the relative area of ​​the comb teeth of the movable electrode 72 and the comb teeth of the fixed electrode 73 changes in the Y-axis direction.

[0049] [Formula 3]

[0050]

[0051] Where Δx represents the displacement of the movable electrode 72 in the X-axis direction, ε represents the dielectric constant, h represents the thickness of the movable electrode 72, d1 and d2 represent the gap between the movable electrode 72 and the fixed electrode 73, L1 and L2 represent the length of the relative portion of the comb teeth, and N1 and N2 represent the number of comb teeth.

[0052] Figure 7 (A) and Figure 7 (B) represents an example of a simulation result based on the FEM (Finite Element Method) for the translational component, rotational component, and rotational component of the mass 60 in the X-axis direction when a force Fx is applied to the boss 40A in the X-axis direction. In the example shown in the figure, the magnitude of the force Fx applied to the boss 40A in the X-axis direction is linearly related to the translational component in the X-axis direction and the rotational component in the Z-axis direction of the mass 60, while the rotational component in the X-axis direction remains unchanged. Furthermore, although the figure is omitted, according to the simulation results based on the FEM (Finite Element Method), the electrostatic capacitance of the first electrode unit 70 is linearly related when a force Fx is applied to the boss 40A in the X-axis direction, but the electrostatic capacitances of the second electrode unit 80 and the third electrode unit 90 remain unchanged.

[0053] Next, the structure of the third electrode unit 90 will be described.

[0054] The third electrode unit 90 is disposed at the four corners of the device layer 30.

[0055] like Figure 8As shown, the third electrode unit 90 includes an electrode holding part 91, movable electrodes 92A and 92B held in the electrode holding part 91, and fixed electrodes 93A and 93B disposed opposite to the movable electrodes 92A and 92B.

[0056] The electrode holding portion 91 is L-shaped when viewed from above, and includes a first electrode holding portion 91A extending along the X-axis direction and a second electrode holding portion 91B extending along the Y-axis direction.

[0057] The first electrode holding portion 91A is connected to the mass portion 60 via the second beam portion 110 and holds the movable electrode 92A. The movable electrode 92A has a comb structure comprising a plurality of flat plate electrodes extending parallel to the Y-axis direction, each serving as a comb tooth. The fixed electrode 93A is held by the electrode holding portion 94 fixed to the device layer 30. The fixed electrode 93A has a comb structure comprising a plurality of flat plate electrodes extending along the Y-axis direction, each serving as a comb tooth. The spacing between the comb teeth of the movable electrode 92A and the fixed electrode 93A is set to the same spacing, and the comb teeth of the movable electrode 92A and the fixed electrode 93A are alternately arranged at intervals in the X-axis direction.

[0058] The second electrode holding part 91B is connected to the mass part 60 via the first beam part 100 and holds the movable electrode 92B. The movable electrode 92B has a comb structure comprising a plurality of flat plates extending along the X-axis direction, each serving as a comb tooth. The fixed electrode 93B is held by an electrode holding part 94 shared with the fixed electrode 93A. The movable electrode 92B has a comb structure comprising a plurality of flat plates extending along the Y-axis direction, each serving as a comb tooth. The spacing between the comb teeth of the movable electrode 92B and the spacing between the comb teeth of the fixed electrode 93B are set to the same spacing, and the comb teeth of the movable electrode 92B and the comb teeth of the fixed electrode 93B are alternately arranged at intervals in the Y-axis direction.

[0059] Furthermore, when the mass section 60 shifts in the Z-axis direction, the driving force generated by the shift of the mass section 60 is converted into rotation about the X-axis with the spring D4 as the rotation axis, and the first unit 110A of the second beam section 110 shifts downward in the Z-axis direction. Additionally, linked to the shift of the first unit 110A of the second beam section 110, the second unit 110B of the second beam section 110 rotates about the X-axis with the spring D3 as the rotation axis. Furthermore, linked to the rotation of the second unit 110B of the second beam section 110 about the X-axis, the first electrode holding section 91A shifts upward in the Z-axis direction. Moreover, the driving force generated by the shift of the mass section 60 is converted into rotation about the Y-axis with the spring D1 as the rotation axis, and the first unit 100A of the first beam section 100 shifts downward in the Z-axis direction. Furthermore, in conjunction with the displacement of the first unit 100A of the first beam 100, the second unit 100B of the first beam 100 rotates about the Y-axis with spring D3 as the rotation axis. Also, in conjunction with the rotation of the second unit 100B about the Y-axis, the second electrode holding part 91B is displaced in a lifting manner in the Z-axis direction. Moreover, as the driving force is transmitted to the first electrode holding part 91A and the second electrode holding part 91B, both the first electrode holding part 91A and the second electrode holding part 91B are displaced in the Z-axis direction. Furthermore, as the first electrode holding part 91A displaces in the Z-axis direction, the relative area of ​​the comb teeth of the movable electrode 92A and the comb teeth of the fixed electrode 93A changes, and the electrostatic capacitance between the movable electrode 92A and the fixed electrode 93A changes. Furthermore, as the second electrode holding part 91B shifts in the Z-axis direction, the relative area of ​​the comb teeth of the movable electrode 92B and the comb teeth of the fixed electrode 93B changes, and the electrostatic capacitance between the movable electrode 92B and the fixed electrode 93B changes. By outputting potential signals representing these changes in electrostatic capacitance from the movable electrodes 92A, 92B and the fixed electrodes 93A, 93B to an external controller, the displacement of the mass part 60 in the Z-axis direction is detected.

[0060] Figure 9 (A) and Figure 9(B) represents an example of a simulation result based on the FEM (Finite Element Method) based on the translational component, rotational component, and rotational component in the X-axis direction of the movable electrode 92 when a force Fz is applied to the boss portion 40A in the Z-axis direction. In the example shown in the figure, the magnitude of the force Fz applied to the boss portion 40A in the Z-axis direction is linearly related to the translational and rotational components in the Z-axis direction of the mass portion 60, while the translational and rotational components in the X-axis direction remain unchanged. Furthermore, although the figure is omitted, according to the simulation results based on the FEM (Finite Element Method), the electrostatic capacitance of the third electrode unit 90 is linearly related when a force Fz is applied to the boss portion 40A in the Z-axis direction, but the electrostatic capacitances of the first electrode unit 70 and the second electrode unit 80 remain unchanged.

[0061] Next, the operation of the electrostatic capacitive sensor 10 in the first embodiment will be explained.

[0062] In this embodiment, when a force is applied to the boss portion 40A, the force is transmitted from the boss portion 40A to the mass portion 60. The movable electrodes of the electrode units 70, 80, and 90 corresponding to the direction of the force shift, thereby changing the electrostatic capacitance of the electrode units 70, 80, and 90. In this case, since the movable electrodes 72, 92A, and 92B and the fixed electrodes 73, 93A, and 93B have a comb-like structure in the electrode units 70, 80, and 90, the area of ​​the movable electrodes 72, 92A, and 92B facing the fixed electrodes 73, 93A, and 93B is large, and the spacing between the movable electrodes 72, 92A, and 92B and the fixed electrodes 73, 93A, and 93B is narrow, the sensitivity of the electrostatic capacitance of the electrode units 70, 80, and 90 increases with the shift of the movable electrodes 72, 92A, and 92B. As a result, the sensitivity of the electrostatic capacitance of the electrode units 70, 80, and 90 can be improved without reducing the thickness of the top cover 40, thus ensuring the mechanical strength of the top cover 40. That is, the sensitivity to detecting externally applied forces can be improved while ensuring mechanical strength.

[0063] Furthermore, if the gap between the top cover 40 and the fixed electrodes 73, 93A, 93B is reduced to improve the sensitivity of the capacitive sensor 10, the maximum allowable displacement of the boss portion 40A is limited. Therefore, the sensitivity and dynamic range of the capacitive sensor 10 are at odds. In this embodiment, the comb-like structure of the movable electrodes 72, 92A, 92B and the fixed electrodes 73, 93A, 93B of the electrode units 70, 80, 90 extends along the displacement direction of the mass portion 60. Thus, while maintaining the gap between the movable electrodes 72, 92A, 92B and the fixed electrodes 73, 93A, 93B, the sensitivity of the electrostatic capacitance of the electrode units 70, 80, 90, which is accompanied by the displacement of the mass portion 60, can be increased. As a result, both the sensitivity and dynamic range of the capacitive sensor 10 can be achieved. Furthermore, as described above, when using a structure in which the displacement of the electrostatic capacitor relative to the boss portion 40A changes linearly, even if the magnitude of the force acting on the boss portion 40A increases, it is possible to maintain the linearity between the magnitude of the applied force and the electrostatic capacitance of the electrostatic capacitive sensor 10.

[0064] Furthermore, in the electrostatic capacitive sensor 10, adjacent electrode units in the first electrode unit 70 located on both sides of the mass unit 60 in the X-axis direction and the second electrode unit 80 located on both sides of the mass unit 60 in the Y-axis direction are connected to each other via a spring D6, which serves as a connecting part. Therefore, when the mass unit 60 performs a translational movement in the X-axis direction, the first unit 110A of the second beam portion 110 located on both sides of the mass unit 60 in the Y-axis direction can follow the mass unit 60 in translating in the X-axis direction without rotating in the XY plane.

[0065] <Second Implementation>

[0066] Next, the electrostatic capacitive sensor 10 of the second embodiment will be described with reference to the accompanying drawings. From the second embodiment onwards, descriptions of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, the same effects achieved by the same structure will not be mentioned repeatedly in each embodiment.

[0067] like Figure 10 As shown, the third electrode unit 90 is divided into multiple electrode units 90α and 90β.

[0068] Electrode unit 90α includes a movable electrode 92α and a fixed electrode 93α disposed opposite to the movable electrode 92α. The movable electrode 92α is held in an electrode holding portion 91α extending along the X-axis direction. The movable electrode 92α has a comb structure comprising a plurality of flat plates extending parallel to the Y-axis direction, each serving as a comb tooth. The fixed electrode 93α is held by an electrode holding portion 94α fixed to the device layer 30. The fixed electrode 93α has a comb structure comprising a plurality of flat plates extending along the Y-axis direction, each serving as a comb tooth. The spacing between the comb teeth of the movable electrode 92α and the fixed electrode 93α is set to the same spacing, and the comb teeth of the movable electrode 92α and the fixed electrode 93α are alternately arranged at intervals in the X-axis direction.

[0069] Electrode unit 90β includes a movable electrode 92β and a fixed electrode 93β disposed opposite to the movable electrode 92β. The movable electrode 92β is held in an electrode holding portion 91β extending along the Y-axis direction. The electrode holding portion 91β is connected to the mass portion 60 via a second beam portion 110. The movable electrode 92β has a comb tooth structure comprising a plurality of flat plate electrodes extending along the X-axis direction, each serving as a comb tooth. The fixed electrode 93β has a first comb tooth structure comprising a plurality of flat plate electrodes extending parallel to the X-axis direction, each serving as a comb tooth. The fixed electrode 93β is held by an electrode holding portion 94β fixed to the device layer 30. The spacing between the comb teeth of the movable electrode 92β and the fixed electrode 93β is set to the same spacing, and the comb teeth of the movable electrode 92β and the fixed electrode 93β are alternately arranged at intervals in the Y-axis direction.

[0070] Furthermore, when the mass section 60 shifts in the Z-axis direction, the driving force generated by the shift of the mass section 60 is transmitted to the electrode holding section 91α via the second beam section 110, causing the electrode holding section 91α to shift in the Z-axis direction. Additionally, as the electrode holding section 91α shifts in the Z-axis direction, the relative area of ​​the comb teeth of the movable electrode 92α and the comb teeth of the fixed electrode 93α changes, resulting in a change in the electrostatic capacitance between the movable electrode 92α and the fixed electrode 93α. Furthermore, the driving force generated by the shift of the mass section 60 is transmitted to the electrode holding section 91β via the first beam 100, causing the electrode holding section 91β to shift in the Z-axis direction. Furthermore, as the electrode holding section 91β shifts in the Z-axis direction, the relative area of ​​the comb teeth of the movable electrode 92β and the comb teeth of the fixed electrode 93β changes, resulting in a change in the electrostatic capacitance between the movable electrode 92β and the fixed electrode 93β. The displacement of the mass unit 60 in the Z-axis direction is detected by outputting potential signals representing changes in these electrostatic capacitances from the movable electrodes 92α, 92β and the fixed electrodes 93α, 93β to an external controller.

[0071] In addition, such as Figure 11As shown, in this embodiment, the structures of the movable electrode 92α and the fixed electrode 93α in electrode unit 90α can also be different from the structures of the movable electrode 92β and the fixed electrode 93β in electrode unit 90β. In the example shown in the figure, the thickness of the movable electrode 92α in the Z-axis direction in electrode unit 90α is greater than the thickness of the fixed electrode 93α in the Z-axis direction, and the thickness of the movable electrode 92β in the Z-axis direction in electrode unit 90β is smaller than the thickness of the fixed electrode 93β in the Z-axis direction. In this case, when setting a difference in the thickness of the movable electrodes 92α, 92β and the fixed electrodes 93α, 93β in the Z-axis direction, it can be any one of top alignment, center alignment, or bottom alignment in the Z-axis direction. Alternatively, the electrode units in electrode units 90α and 90β can be uniformly aligned in the Z-axis direction as top-aligned, center-aligned, or bottom-aligned. For example, one electrode unit in electrode units 90α and 90β can be top-aligned in the Z-axis direction, and the other electrode unit can be bottom-aligned in the Z-axis direction, so that the Z-axis arrangements of the movable electrodes 92α, 92β and the fixed electrodes 93α, 93β in each electrode unit 90α, 90β are different from each other. Furthermore, when the movable electrode 92β moves relative to the fixed electrode 93β in the Z-axis direction in conjunction with the mass unit 60 as the mass unit 60 moves in the Z-axis direction, the changes in the relative areas of the movable electrodes 92α, 92β and the fixed electrodes 93α, 93β between electrode units 90α and 90β are different, and the changes in electrostatic capacitance are also different. Furthermore, the electrostatic capacitance changes not only based on the change in the relative area of ​​the movable electrodes 92α, 92β and the fixed electrodes 93α, 93β, but also based on the bending effect of the electric field lines between the movable electrodes 92α, 92β and the fixed electrodes 93α, 93β. Therefore, potential signals representing the change in electrostatic capacitance are individually output from the movable electrodes 92α and the fixed electrodes 93α and 92β and the fixed electrodes 93β to an external controller. By calculating the difference between these output values, the displacement of the mass unit 60 in the Z-axis direction can be detected more accurately and in greater detail.

[0072] Furthermore, the above-described implementation method can also be implemented in the following manner.

[0073] In the above embodiments, springs D1, D2, D4, D5, and D7 may also be disposed at multiple locations in the device layer 30 and configured to have different thicknesses.

[0074] In the above embodiments, such as Figure 12As shown, for the first electrode unit 70, the structures of spring D1 and spring D7 can also be different from each other. In the example shown in the figure, the thickness of spring D7 in the Z direction is greater than the thickness of spring D1 in the Z direction. In this case, the ratio of the elastic force in the Y direction of spring D7 to the elastic force in the Z direction of spring D7 is less than the ratio of the elastic force in the Y direction of spring D1 to the elastic force in the Z direction of spring D1. This is because the spring constants in the Z direction of springs D1 and D7 are proportional to the cube of the thicknesses in the Z direction of springs D1 and D7, and the spring constants in the Y direction of springs D1 and D7 are proportional to the first power of the thicknesses in the Z direction of springs D1 and D7, and their ratio decreases proportionally to the square of the thicknesses in the Z direction of springs D1 and D7. In this way, by controlling the ratio of the elastic forces in the in-plane and out-of-plane directions of springs D1 and D7, it is possible to suppress the sensitivity of displacement in the X-axis and Y-axis directions relative to the mass part 60 while also improving the sensitivity of displacement in the Z-axis direction relative to the mass part 60.

[0075] In the above embodiments, such as Figure 13 As shown, the first electrode unit 70 may also include a stop member M1 as an example of a limiting portion restricting the displacement of the device layer 30 in the planes along the X-axis and Y-axis directions, and a stop member M2 as an example of a limiting portion restricting the displacement of the device layer 30 in the Z-axis direction. Similarly, the second electrode unit 80 is also included. In this case, the first electrode unit 70 or the second electrode unit 80 preferably also has an adhesion-suppressing portion that suppresses adhesion (so-called sticking) relative to the stop members M1 and M2. The adhesion-suppressing portion of the first electrode unit 70 or the second electrode unit 80 is, for example, a protrusion that protrudes relative to the stop member M1 or the stop member M2. The area of ​​the end of the protrusion is smaller than the area of ​​the surface of the first electrode unit 70 or the second electrode unit 80 opposite to the stop member M1 or the stop member M2. Such a protrusion reduces the contact area between the first electrode unit 70 or the second electrode unit 80 and the stop members M1 and M2, thereby suppressing the formation of adhesion. The shape of the protrusion is not particularly limited; for example, it can be spherical, columnar, conical, frustum-shaped, or a combination thereof.

[0076] In the above embodiments, such as Figure 14 As shown, the third electrode unit 90 may also include a stop member M1 as an example of a limiting portion restricting the displacement of the limiting device layer 30 in the plane along the X-axis and Y-axis directions, and a stop member M2 as an example of a limiting portion restricting the displacement of the limiting device layer 30 in the Z-axis direction. In this case, the third electrode unit 90 preferably also has an adhesion suppression portion that suppresses adhesion relative to the stop members M1 and M2. The adhesion suppression portion of the third electrode unit 90 is similar to the adhesion suppression portion of the first electrode unit 70 or the second electrode unit 80, for example, a protrusion that protrudes relative to the stop member M1 or the stop member M2.

[0077] The following are some or all of the embodiments of the present invention. Furthermore, the present invention is not limited to the following descriptions.

[0078] <1>

[0079] An electrostatic capacitive sensor detects a force acting in at least one of a first, second, and third direction based on a change in the electrostatic capacitance of an electrode unit consisting of a first comb-tooth structure and a second comb-tooth structure opposite to the first comb-tooth structure. The second direction intersects the first direction, and the third direction intersects both the first and second directions.

[0080] This electrostatic capacitive sensor features:

[0081] A first substrate layer, having a thickness direction in the third direction, has a boss portion that receives forces acting in the at least one direction; and

[0082] The second substrate layer, having the third direction as its thickness direction, has a mass portion, a movable electrode, and a fixed electrode. Forces acting in at least one direction are transmitted from the boss portion to the mass portion. The movable electrode has the first comb tooth structure and is displaced in conjunction with the mass portion. The fixed electrode has the second comb tooth structure.

[0083] <2>

[0084] According to the electrostatic capacitive sensor described in <1>, wherein,

[0085] The electrostatic capacitive sensor detects forces acting in at least one direction based on the change in the electrostatic capacitance of the electrode unit accompanying the change in the relative area of ​​the first comb structure and the second comb structure.

[0086] <3>

[0087] According to the electrostatic capacitive sensor described in <2>, wherein,

[0088] The electrode unit includes:

[0089] As the mass part shifts in the first direction, the relative area of ​​the first comb structure and the second comb structure of the first electrode unit changes.

[0090] In the second electrode unit, as the mass portion shifts in the second direction, the relative area of ​​the first comb-tooth structure and the second comb-tooth structure of the second electrode unit changes; and

[0091] As the mass part shifts in the third direction, the relative area of ​​the first comb structure and the second comb structure of the third electrode unit changes.

[0092] <4>

[0093] According to the electrostatic capacitive sensor described in <3>, wherein...

[0094] The first electrode unit is arranged in pairs on one side and the other side in the first direction, with the mass part as a reference.

[0095] The second electrode unit is arranged in pairs on one side and the other side in the second direction, with the mass part as a reference.

[0096] The electrostatic capacitive sensor also includes a connecting portion that connects adjacent electrode units in a pair of first electrode units and a pair of second electrode units to each other.

[0097] <5>

[0098] According to the electrostatic capacitive sensor described in <3> or <4>, wherein,

[0099] The third electrode unit is divided into multiple electrode units.

[0100] The electrostatic capacitive sensor detects the magnitude of the force acting on the boss in the third direction based on the change in the electrostatic capacitance of each of the multiple electrode units divided in the third electrode unit, which occurs in conjunction with the change in the relative area of ​​the first comb structure and the second comb structure of each of the multiple electrode units divided in the third electrode unit.

[0101] <6>

[0102] According to the electrostatic capacitive sensor described in <5>, wherein,

[0103] The multiple electrode units divided into the third electrode unit are configured as movable electrodes with different thicknesses.

[0104] <7>

[0105] According to any one of <3> to <6>, the electrostatic capacitive sensor, wherein,

[0106] This electrostatic capacitive sensor also features:

[0107] The first elastic part connects the mass part to the first electrode unit in a manner that restricts displacement in the first direction and allows displacement in the second direction;

[0108] A second elastic portion connects the mass portion to the second electrode unit in a manner that restricts displacement in the second direction while allowing displacement in the first direction; and

[0109] The third elastic part connects the mass part to the third electrode unit in a manner that restricts displacement in the first and second directions and allows rotation centered on an axis extending in the plane along the first and second directions.

[0110] <8>

[0111] According to the electrostatic capacitive sensor described in <7>, wherein...

[0112] The first elastic portion, the second elastic portion, and the third elastic portion are respectively disposed at multiple locations in the second substrate layer.

[0113] The first elastic portion, the second elastic portion, and the third elastic portion, which are disposed at various locations, are configured to have different thicknesses.

[0114] <9>

[0115] According to any one of <1> to <8>, the electrostatic capacitive sensor, wherein,

[0116] The electrostatic capacitive sensor also includes a limiting portion that limits at least one of the displacement of the second substrate layer in a plane along the first and second directions and the displacement of the second substrate layer in the third direction.

[0117] <10>

[0118] According to the electrostatic capacitive sensor described in <9>, wherein...

[0119] The second substrate layer also has an adhesion suppression portion that suppresses adhesion relative to the limiting portion.

[0120] As explained above, according to a technical solution of the present invention, an electrostatic capacitive sensor can be provided that can improve the detection sensitivity of externally applied forces while ensuring mechanical strength.

[0121] Furthermore, the embodiments described above are intended to facilitate understanding of the present invention and are not intended to limit the scope of the invention. The present invention can be modified / improved without departing from its spirit, and the present invention also includes its equivalents. That is, embodiments obtained by those skilled in the art through appropriate design modifications to the embodiments, as long as they possess the features of the present invention, are also included within the scope of the present invention. For example, the elements, their configurations, materials, conditions, shapes, dimensions, etc., of each embodiment are not limited to the illustrated contents and can be appropriately modified. In addition, the embodiments are illustrative, and it is self-evident that partial substitutions or combinations of the structures shown in different embodiments are possible; such substitutions or combinations, as long as they contain the features of the present invention, are also included within the scope of the present invention.

[0122] Explanation of reference numerals in the attached figures

[0123] 10. Electrostatic capacitive sensor; 20. Lower cover; 30. Device layer; 40. Upper cover; 40A. Boss part; 60. Mass part; 70. First electrode unit; 80. Second electrode unit; 90. Third electrode unit.

Claims

1. An electrostatic capacitive sensor that detects a force acting in at least one of a first direction, a second direction, and a third direction based on a change in the electrostatic capacitance of an electrode unit consisting of a first comb-tooth structure and a second comb-tooth structure opposite to the first comb-tooth structure, wherein the second direction intersects the first direction, and the third direction intersects both the first and second directions, wherein, This electrostatic capacitive sensor features: The first substrate layer has a boss portion that receives a force acting in the at least one direction, with the third direction as its thickness direction, and the first substrate layer flexes and deforms based on the force acting on the boss portion. as well as The second substrate layer, having the third direction as its thickness direction, has a mass portion, a movable electrode, and a fixed electrode. Forces acting in at least one direction are transmitted from the boss portion to the mass portion. The movable electrode has the first comb tooth structure and is displaced in conjunction with the mass portion. The fixed electrode has the second comb tooth structure.

2. The electrostatic capacitive sensor according to claim 1, wherein, The electrostatic capacitive sensor detects forces acting in at least one direction based on the change in the electrostatic capacitance of the electrode unit that occurs in conjunction with the change in the relative area of ​​the first comb structure and the second comb structure.

3. The electrostatic capacitive sensor according to claim 2, wherein, The electrode unit includes: As the mass part shifts in the first direction, the relative area of ​​the first comb structure and the second comb structure of the first electrode unit changes. In the second electrode unit, as the mass portion shifts in the second direction, the relative area of ​​the first comb-tooth structure and the second comb-tooth structure of the second electrode unit changes; and As the mass part shifts in the third direction, the relative area of ​​the first comb structure and the second comb structure of the third electrode unit changes.

4. The electrostatic capacitive sensor according to claim 3, wherein, The first electrode unit is arranged in pairs on one side and the other side in the first direction, with the mass part as a reference. The second electrode unit is arranged in pairs on one side and the other side in the second direction, with the mass part as a reference. The electrostatic capacitive sensor also includes a connecting portion that connects adjacent electrode units in a pair of first electrode units and a pair of second electrode units to each other.

5. The electrostatic capacitive sensor according to claim 3 or 4, wherein, The third electrode unit is divided into multiple electrode units. The electrostatic capacitive sensor detects the magnitude of the force acting on the boss in the third direction based on the change in the electrostatic capacitance of each of the multiple electrode units divided in the third electrode unit, which occurs in conjunction with the change in the relative area of ​​the first comb structure and the second comb structure of each of the multiple electrode units divided in the third electrode unit.

6. The electrostatic capacitive sensor according to claim 5, wherein, The multiple electrode units divided into the third electrode unit are configured as movable electrodes with different thicknesses.

7. The electrostatic capacitive sensor according to any one of claims 3 to 6, wherein, This electrostatic capacitive sensor also features: The first elastic part connects the mass part to the first electrode unit in a manner that restricts displacement in the first direction and allows displacement in the second direction; The second elastic part connects the mass part to the second electrode unit in a manner that restricts displacement in the second direction while allowing displacement in the first direction; as well as The third elastic part connects the mass part to the third electrode unit in a manner that restricts displacement in the first and second directions and allows rotation centered on an axis extending in the plane along the first and second directions.

8. The electrostatic capacitive sensor according to claim 7, wherein, The first elastic portion, the second elastic portion, and the third elastic portion are respectively disposed at multiple locations in the second substrate layer. The first elastic portion, the second elastic portion, and the third elastic portion, which are disposed at various locations, are configured to have different thicknesses.

9. The electrostatic capacitive sensor according to any one of claims 1 to 8, wherein, The electrostatic capacitive sensor also includes a limiting portion that limits at least one of the displacement of the second substrate layer in a plane along the first and second directions and the displacement of the second substrate layer in the third direction.

10. The electrostatic capacitive sensor according to claim 9, wherein, The second substrate layer also has an adhesion suppression portion that suppresses adhesion relative to the limiting portion.

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