Physical quantity sensors and inertial measurement devices

Abstract

To provide a physical quantity sensor and an inertial measurement unit that can avoid a problem accompanying the imbalance in mass distribution.SOLUTION: A physical quantity sensor 1 includes stationary parts 40A, 40B, support beams 42A, 42B, a movable body MB, and first stationary electrode groups 10A, 10B. The movable body MB is connected to the other ends of the support beams 42A, 42B, and the first stationary electrode groups 10A, 10B are provided on a substrate 2 and arranged in a first direction DR1 of the support beams 42A, 42B. The movable body MB has first connection parts 30A, 30B, a first base part 23, and first movable electrode groups 20A, 20B. The first movable electrode groups 20A, 20B face the first stationary electrode groups 10A, 10B in a second direction DR2. When the height of the center of gravity in a third direction DR3 of the movable body MB is defined as hm, and the height in the third direction DR3 of the center of rotation of the support beams 42A, 42B as hr, hm=hr.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a physical quantity sensor, an inertial measurement device, and the like. [Background Art]

[0002] Patent Document 1 discloses a physical quantity sensor that detects acceleration in the Z direction. It is disclosed that in the physical quantity sensor, the length of one first electrode of the plurality of first electrodes along the first direction is shorter than the length of the first conductive portion along the first direction. It is also disclosed that in the physical quantity sensor, the length of one second electrode of the plurality of second electrodes along the first direction is shorter than the length of the second conductive portion along the first direction. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2021-032819 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In the physical quantity sensor disclosed in Patent Document 1, when acceleration is applied in the length direction of the comb electrode, which is not the Z-axis direction that is the detection target, the same seesaw operation occurs as when acceleration is applied in the detection axis direction, which causes a problem of increased cross-axis sensitivity. [Means for Solving the Problem]

[0005] One aspect of the present disclosure relates to a physical quantity sensor for detecting a physical quantity in a third direction, where three mutually orthogonal directions are designated as a first direction, a second direction, and a third direction, and includes a fixed part fixed to a substrate, a support beam with one end connected to the fixed part and provided along the second direction, a movable body connected to the other end of the support beam, and a first fixed electrode group provided on the substrate and arranged in the first direction of the support beam, wherein the movable body has a first connecting part connected to the other end of the support beam and extending from the support beam in the first direction, a first base part connected to the first connecting part and provided along the second direction, and a first movable electrode group provided on the first base part and facing the first fixed electrode group in the second direction, and the physical quantity sensor is such that when the height of the center of gravity of the movable body in the third direction is hm and the height of the rotation center of the support beam in the third direction is hr, then hm = hr.

[0006] Another aspect of this disclosure relates to an inertial measuring device that includes the physical quantity sensor described above and a control unit that performs control based on a detection signal output from the physical quantity sensor. [Brief explanation of the drawing]

[0007] [Figure 1] An example configuration of the physical quantity sensor in this embodiment. [Figure 2] A perspective view of the physical quantity sensor of this embodiment. [Figure 3] Perspective view of the detection unit. [Figure 4] Operational diagram of the detection unit. [Figure 5] A diagram illustrating the positional relationship of the center of gravity of each component in this embodiment. [Figure 6] A schematic cross-sectional view showing the relationship between the center of gravity and inertial force of a movable body when this embodiment is not applied. [Figure 7] A schematic cross-sectional view showing the relationship between the center of gravity and inertial force of the movable body when this embodiment is applied. [Figure 8] A plan view of the first detailed example of this embodiment. [Figure 9] A perspective view of the first detailed example of this embodiment. [Figure 10] A perspective view of the detection unit in the first detailed example of this embodiment. [Figure 11] A diagram illustrating the operation of the detection unit in the first detailed example of this embodiment. [Figure 12] A plan view of a second detailed example of this embodiment. [Figure 13] A perspective view of a second detailed example of this embodiment. [Figure 14] A perspective view of the detection unit in a third detailed example of this embodiment. [Figure 15] A diagram illustrating the operation of the detection unit in a third detailed example of this embodiment. [Figure 16] A diagram illustrating the positional relationship of the center of gravity of each component in the third detailed example of this embodiment. [Figure 17] A schematic cross-sectional diagram showing the relationship between the center of gravity and inertial force of the movable body in the third detailed example. [Figure 18] An example of the arrangement pattern of fixed and movable electrodes in the YZ cross-section in the third detailed example. [Figure 19] An exploded perspective view showing the schematic configuration of an inertial measurement device equipped with physical quantity sensors. [Figure 20] Perspective view of the circuit board of a physical quantity sensor. [Modes for carrying out the invention]

[0008] The following describes this embodiment. Note that the embodiment described below does not unduly limit the scope of the claims. Furthermore, not all of the configurations described in this embodiment are necessarily essential components.

[0009] 1. Physical quantity sensor In this embodiment, the physical quantity sensor 1 will be described using an acceleration sensor that detects vertical acceleration as an example. Figure 1 is a plan view of the physical quantity sensor 1 of this embodiment in a direction perpendicular to the substrate 2. The physical quantity sensor 1 is a MEMS (Micro Electro Mechanical Systems) device, such as an inertial sensor.

[0010] Note that in Figure 1 and Figures 2 to 18 described later, the dimensions of each component and the spacing between components are shown schematically for the sake of explanation, and not all components are shown. For example, electrode wiring and electrode terminals are omitted from the illustration. In the following explanation, the physical quantity detected by the physical quantity sensor 1 is mainly used as an example, but the physical quantity is not limited to acceleration and may be other physical quantities such as velocity, pressure, displacement, attitude, angular velocity, or gravity, and the physical quantity sensor 1 may be used as a pressure sensor or a MEMS switch, etc. Also, in Figure 1, the mutually orthogonal directions are referred to as the first direction DR1, the second direction DR2, and the third direction DR3. The first direction DR1, the second direction DR2, and the third direction DR3 are, for example, the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively, but are not limited to these. For example, the third direction DR3 corresponding to the Z-axis direction is, for example, the direction orthogonal to the substrate 2 of the physical quantity sensor 1, for example, the vertical direction. The direction opposite to the third direction DR3 is referred to as the fifth direction DR5. The first direction DR1, corresponding to the X-axis direction, and the second direction DR2, corresponding to the Y-axis direction, are perpendicular to the third direction DR3. The XY plane, which is the plane along the first direction DR1 and the second direction DR2, is, for example, aligned with the horizontal plane. The direction opposite to the first direction DR1 is the fourth direction DR4, and the fourth direction is, for example, the -X-axis direction. Note that "orthogonal" includes not only intersections at 90° but also intersections at angles slightly tilted from 90°.

[0011] The substrate 2 is, for example, a silicon substrate made of semiconductor silicon or a glass substrate made of a glass material such as borosilicate glass. However, the constituent material of the substrate 2 is not particularly limited, and a quartz substrate or an SOI (Silicon On Insulator) substrate may also be used.

[0012] As shown in Figure 1, the physical quantity sensor 1 of this embodiment includes fixed parts 40A, 40B, support beams 42A, 42B, a movable body MB, and first fixed electrode groups 10A, 10B. The movable body MB includes first connecting parts 30A, 30B, a first base part 23, and first movable electrode groups 20A, 20B. The first fixed electrode group 10A has a plurality of first fixed electrodes 11A, and the first fixed electrode group 10B has a plurality of first fixed electrodes 11B. The first movable electrode group 20A has a plurality of first movable electrodes 21A, and the first movable electrode group 20B has a plurality of first movable electrodes 21B.

[0013] As shown by the dashed frame in Figure 1, the physical quantity sensor 1 has a detection unit Z1 and a detection unit Z2, and each detection unit detects physical quantities such as acceleration in the direction along the third direction DR3, which is the Z-axis direction. In a plan view, the detection units Z1 and Z2 are provided on the first direction DR1 side and the fourth direction DR4 side of the first base 23, respectively. The detection unit Z1 provided on the fourth direction DR4 side of the first base 23 includes a first fixed electrode group 10A and a first movable electrode group 20A. The detection unit Z2 provided on the first direction DR1 side of the first base 23 includes a first fixed electrode group 10B and a first movable electrode group 20B.

[0014] Figure 2 is a perspective view of the physical quantity sensor 1 of this embodiment. The fixed parts 40A and 40B are provided on the substrate 2 as shown in Figure 2. Fixed part 40A fixes one end of the support beam 42A to the substrate 2 and is connected to the first connecting part 30A of the movable body MB. Fixed part 40B is connected to one end of the support beam 42B and is connected to the first connecting part 30B of the movable body MB. In this way, the fixed parts 40A and 40B connect the movable body MB to the substrate 2 via the support beams 42A and 42B. The fixed parts 40A and 40B then play the role of anchors in the seesaw motion of the movable body MB, which will be explained later in Figure 4.

[0015] Support beams 42A and 42B provide a restoring force during the seesaw motion of the movable body MB. As shown in Figure 2, one end of each support beam 42A and 42B is connected to a part of the fixed section 40A and 40B. The other end of each support beam 42A and 42B is connected to the first connecting section 30A and 30B, respectively. In this way, the support beams 42A and 42B connect the fixed section 40A and 40B to the movable body MB. The support beams 42A and 42B are, for example, torsion springs. As shown in Figure 1, in a plan view, the support beams 42A and 42B are provided such that, for example, the second direction DR2 is the longitudinal direction. The thickness of the support beams 42A and 42B is thinner in the first direction DR1, so that they flex in response to the movement of the movable body MB. Then, by twisting in the second direction DR2, for example along the Y axis, they provide a restoring force during the seesaw motion of the movable body MB. Thus, in this embodiment, the support beams 42A and 42B are torsion springs that twist around the second direction DR2 as the axis of rotation. In this way, the movable body MB can perform an oscillating motion around the second direction DR2 as the axis of rotation.

[0016] The movable body MB oscillates, for example, around a rotation axis along the second direction DR2. That is, the movable body MB performs a seesaw motion using the torsion of the support beams 42A and 42B as a restoring force in its rotational motion around the second direction DR2. Then, the first movable electrode group 20A and 20B of the movable body MB are used as probe electrodes to detect physical quantities.

[0017] The first connecting portion 30A connects the other end of the support beam 42A that is not connected to the fixed portion 40A to the first base portion 23. The first connecting portion 30B connects the other end of the support beam 42B that is not connected to the fixed portion 40B to the first base portion 23. In this way, the first connecting portions 30A and 30B connect the first movable electrode groups 20A and 20B of the movable body MB so that they are positioned at a certain distance from the axis of rotation of the seesaw motion.

[0018] The first base portion 23 connects the first connecting portion 30A and the first connecting portion 30B, and also serves as a base for supporting the first movable electrode groups 20A and 20B provided on the movable body MB. Specifically, the first base portion 23 is connected to the fixed portions 40A and 40B, respectively, and connects the first connecting portions 30A and 30B so that the movable body can perform seesaw motion as a single unit. The first movable electrode group 20A is configured to include a plurality of first movable electrodes 21A extending from the first base portion 23 toward the fourth direction DR4, and the first movable electrode group 20B is configured to include a plurality of first movable electrodes 21B extending from the first base portion 23 toward the first direction DR1.

[0019] The first movable electrode groups 20A and 20B, and the first fixed electrode groups 10A and 10B are probes for detecting physical quantities. As described above, the first movable electrode groups 20A and 20B are provided on the fourth direction DR4 side and the first direction DR1 side of the first base 23, respectively. The first fixed electrode groups 10A and 10B are fixed to the substrate 2 by a fixing part. In the first fixed electrode groups 10A and 10B, multiple first fixed electrodes 11A and 11B are provided so as to extend along the first direction DR1, for example. The first fixed electrodes 11A and 11B each form an electrode group arranged in a comb-like pattern. Note that the number of first fixed electrodes 11A and 11B is not limited to the four shown in Figure 1, but can be provided arbitrarily. Similarly, the number of electrodes in the first movable electrodes 21A and 21B can also be provided arbitrarily.

[0020] As shown in Figure 1, the first movable electrode 21A of the first movable electrode group 20A is positioned to face the first fixed electrode 11A of the first fixed electrode group 10A in the second direction DR2. Similarly, the first movable electrode 21B of the first movable electrode group 20B is positioned to face the first fixed electrode 11B of the first fixed electrode group 10B in the second direction DR2. The portion where the first movable electrode 21A and the first fixed electrode 11A are positioned facing each other becomes the detection unit Z1. The portion where the first movable electrode 21B and the first fixed electrode 11B are positioned facing each other becomes the detection unit Z2.

[0021] Figure 3 is a perspective view showing the electrode structure of detection units Z1 and Z2 in this embodiment. As shown in Figure 3, in detection unit Z1, the first fixed electrode 11A and the first movable electrode 21A have different thicknesses in the third direction DR3. Similarly, in detection unit Z2, the first fixed electrode 11B and the first movable electrode 21B also have different thicknesses in the third direction DR3. Specifically, in detection unit Z1, the thickness of the first movable electrode 21A in the third direction DR3 is greater than the thickness of the first fixed electrode 11A in the third direction DR3. On the other hand, in detection unit Z2, the thickness of the first movable electrode 21B in the third direction DR3 is thinner than the thickness of the first fixed electrode 11B in the third direction DR3. Furthermore, the thickness of the first fixed electrode 11A of the detection unit Z1 and the first movable electrode 21B of the detection unit Z2 in the third direction DR3 are equal, and the thickness of the first movable electrode 21A of the detection unit Z1 and the first fixed electrode 11B of the detection unit Z2 in the third direction DR3 is the same as the thickness of the first base unit 23 in the third direction DR3. Here, thickness is not limited to the physical thickness measured by, for example, the cross-section of the element using an SEM (Scanning Electron Microscope), but also includes the film thickness estimated from optical properties such as the refractive index of the thin film.

[0022] Figure 4 illustrates the operation of detection units Z1 and Z2 of the physical quantity sensor 1 in this embodiment. Specifically, it shows a schematic cross-sectional view from the first direction DR1 of the movement of the probe electrode with respect to the direction of acceleration when acceleration occurs from the initial state. Here, the initial state refers to a stationary state, that is, a state in which no acceleration occurs except for gravitational acceleration. Detection unit Z1 corresponds to the P side of the probe, and detection unit Z2 corresponds to the N side of the probe.

[0023] First, in the initial state shown on the left side of Figure 4, the first fixed electrode 11A and the first movable electrode 21A of the detection unit Z1 are positioned opposite each other along the third direction DR3, with a portion of each overlapping. Specifically, the ends of the first fixed electrode 11A and the first movable electrode 21A coincide in the fifth direction DR5, but in the third direction DR3, the end of the first movable electrode 21A is positioned further towards the third direction DR3 than the end of the first fixed electrode 11A. In the initial state, the first fixed electrode 11A and the first movable electrode 21A are stationary in this state, with a portion of each overlapping along the third direction DR3. Similarly, the first fixed electrode 11B and the first movable electrode 21B of the detection unit Z2 are also positioned opposite each other along the third direction DR3, with a portion of each overlapping. In the detection unit Z2, the end of the first fixed electrode 11B is positioned further towards the third direction DR3 than the end of the first movable electrode 21B.

[0024] In this initial state, the physical quantity in the initial state is the sum of the physical quantity corresponding to the opposing area between the first fixed electrode 11A and the first movable electrode 21A in the detection unit Z1, and the physical quantity corresponding to the opposing area between the first fixed electrode 11B and the first movable electrode 21B in the detection unit Z2. Examples of such physical quantities include capacitance.

[0025] Next, we will explain the state in which acceleration in the third direction DR3 occurs, as shown in the center of Figure 4. In the state in which acceleration in the third direction DR3 occurs, the first movable electrodes 21A and 21B in detection units Z1 and Z2 are subjected to an inertial force in the opposite direction to the direction of acceleration. As a result, the first movable electrode 21A of detection unit Z1 is displaced toward the fifth direction DR5, and the first movable electrode 21B of detection unit Z2 is also displaced toward the fifth direction DR5. As a result, in detection unit Z1, the opposing area between the first fixed electrode 11A and the first movable electrode 21A is maintained as shown in Figure 4, while in detection unit Z2, the opposing area between the first fixed electrode 11B and the first movable electrode 21B decreases. Therefore, by detecting the change in physical quantity due to the decrease in the opposing area in detection unit Z2, the physical quantity in the third direction DR3 can be detected.

[0026] On the other hand, as shown on the right side of Figure 4, when acceleration in the fifth direction DR5 occurs from the initial state, the first movable electrodes 21A and 21B in detection units Z1 and Z2 are subjected to an inertial force in the +Z direction. As a result, in detection unit Z1, the first movable electrode 21A is displaced toward the third direction DR3, i.e., in the +Z direction, and the first movable electrode 21B in detection unit Z2 is also displaced in the +Z direction. Consequently, in detection unit Z1, the opposing area between the first fixed electrode 11A and the first movable electrode 21A decreases, while in detection unit Z2, the opposing area between the first fixed electrode 11B and the first movable electrode 21B is maintained. Therefore, by detecting the change in physical quantity due to the decrease in the opposing area in detection unit Z1, the physical quantity of the fifth direction DR5 can be detected. When detecting a change in capacitance as a physical quantity, for example, capacitance can be detected by connecting the first fixed electrodes 11A and 11B and the first movable electrodes 21A and 21B to a differential amplifier circuit (not shown) via wiring and pads, respectively.

[0027] Figure 5 is a schematic cross-sectional view of the first movable electrode group 20A, 20B, the first base 23, the first connecting parts 30A, 30B, and the support beams 42A, 42B of this embodiment, as viewed from the second direction DR2. Note that Figure 5 focuses on the difference in thickness of each component in the third direction DR3, and therefore the dimensions of each component are not shown precisely.

[0028] In this embodiment, the first movable electrode group 20A, the first base 23, and the first connecting parts 30A and 30B of the detection unit Z1 have the greatest thickness in the third direction DR3. The thickness decreases in the third direction DR3 in the order of the support beams 42A and 42B, and the first movable electrode group 20B.

[0029] In Figure 5, the black circles indicated on each component represent the center of gravity of each component. Here, the center of gravity of the first movable electrode group 20A is G Z1 The center of gravity of the first movable electrode group 20B is set to G Z2 The center of gravity of the movable body MB is denoted as Gm, and the center of gravity of the support beams 42A and 42B are denoted as Gr. For example, in the first movable electrode group 20A shown on the left side of Figure 5, the center of gravity of the multiple first movable electrodes 21A included in the first movable electrode group 20A is denoted as Gm, when viewed as a whole in the third direction DR3.Z1 indicates that there is. As described with reference to FIG. 3, the thickness of the first movable electrode 21B of the first movable electrode group 20B in the third direction DR3 is smaller than that of the first movable electrode 21A, so the center of gravity G at the center position of the first movable electrode 21B Z2 is also located more toward the fifth direction DR side than the center of gravity G of the first movable electrode group 20A, that is, Z1 on the -Z direction side.

[0030] Here, the center of gravity refers to the center position of the mass distribution in a target component. Therefore, if there is no uniformity in the mass distribution of the target component, the center of gravity position may not necessarily be the center position of each component in the third direction DR3 as described above.

[0031] In FIG. 5, a center of gravity position Gm is indicated on the third movable body MB from the left. The center of gravity position Gm of the movable body MB indicates the center of gravity position when the movable body MB is regarded as a member integrally formed by a plurality of components including the first movable electrode groups 20A and 20B, the first base portion 23, and the first connecting portions 30A and 30B. As described above, the center of gravity G of the first movable electrode group 20A Z1 and the center of gravity G of the first movable electrode group 20B Z2 are shifted in the third direction DR3, so the center of gravity position Gm of the movable body MB including these is located between the center of gravity position G Z1 and the center of gravity position G Z2 . Note that since the movable body MB is an assembly of a plurality of components, only the center of gravity position is shown in FIG. 5. The position of the center of gravity Gm of the movable body MB in the third direction DR3 matches the position of the center of gravity Gr of the support beams 42A and 42B in the third direction DR3. That is, in the present embodiment, the center of gravity G of the first movable electrode group 20A Z1 , the center of gravity G of the first movable electrode group 20B Z2 , the positional relationship among the center of gravity Gm of the movable body MB and the center of gravity Gr of the support beams 42A and 42B in the third direction DR3 satisfies G Z1 >Gm=Gr>G Z2 . As described above, in the present embodiment, the positional relationship of the center of gravity positions of the respective components in the third direction DR3 satisfies G Z1 >Gm=Gr>G Z2The thickness of the third direction DR3 of the first movable electrode group 20B and the support beams 42A and 42B is designed accordingly.

[0032] As mentioned above, the center of gravity refers to the central position of the mass distribution in the component in question. Therefore, if the mass distribution is not uniform in each component, the center of gravity will not necessarily be in the center of each component. Consequently, regardless of the thickness or shape of each component in the third direction DR3, the center of gravity Gm of the movable body MB and the center of gravity Gr of the support beams 42A and 42B may coincide in the third direction DR3. Furthermore, in this embodiment, even if the thickness and shape of each component do not have the relative sizes shown in Figure 5, it is sufficient that the center of gravity Gm of the movable body MB and the center of gravity Gr of the support beams 42A and 42B coincide in the third direction DR3.

[0033] Furthermore, the statement that the positions in the third direction DR3 coincide as described above means that they are approximately coincident. For example, when performing etching in a semiconductor manufacturing process, even if the process is carried out under the same equipment and conditions, variations in the finished dimensions will occur due to the equipment itself. For this reason, it is common practice to manage the process by setting a certain margin relative to the target processing dimensions. For these reasons, the positions of the center of gravity Gm of the movable body MB and the center of gravity Gr of the support beams 42A and 42B in the third direction DR3 do not usually coincide perfectly. Therefore, the statement that the positions in the third direction DR3 coincide as described above includes cases where they are approximately coincident.

[0034] Figures 6 and 7 are schematic cross-sectional views of the physical quantity sensor 1 as seen from the -Y direction, illustrating the case where the physical quantity sensor 1 is subjected to an inertial force FI in the first direction DR1. Note that in Figure 6, the first connecting parts 30A and 30B, the fixing parts 40A and 40B, and the substrate 2 are omitted from the display.

[0035] Figure 6 shows the physical quantity sensor 1 when this embodiment is not applied. That is, the positional relationship of the center of gravity of each component in the third direction DR3 is as described in Figure 5, G Z1 >Gm=Gr>G Z2This relationship does not exist. In the physical quantity sensor shown in Figure 6, the thickness of the support beams 42A and 42B in the third direction DR3 is the same as the thickness of the first movable electrode group 20A, the first connecting parts 30A and 30B (not shown), or the first base part 23. Therefore, the positional relationship of the center of gravity of each component in the third direction DR3 is G Z1 =Gr>Gm>G Z2 That is the relationship.

[0036] Here, the center of gravity position Gm of the movable body MB and the center of gravity position G of the detection unit Z1. Z1 , center of gravity position G of detection unit Z2 Z2 Let the heights of each component in the third direction DR3 be hm, hm1, and hm2. Also, let the height of the center of gravity position Gr of the support beams 42A and 42B in the third direction DR3 be hr. Here, height refers to the height in the third direction DR3 with respect to the lower ends of the support beams 42A and 42B in the third direction DR3, when the stationary state is defined as when the first connecting parts 30A and 30B of the physical quantity sensor 1 are horizontal with respect to the XY plane. Furthermore, the positional relationship of the center of gravity of each component in the third direction DR3, as explained in Figure 5, is G Z1 =Gr>Gm>G Z2 If such a relationship exists, then the heights of the center of gravity of each component, hm, hm1, hm2, and hr, satisfy the relationship hm1=hr>hm>hm2.

[0037] The following considers the case where each component of the physical quantity sensor 1 has the shape shown in Figure 6. In Figure 6, when acceleration in the fourth direction DR4, i.e., the -X direction, occurs in the physical quantity sensor 1, an inertial force FI in the opposite direction, the +X direction, acts on the movable body MB. Here, the movable body MB can be considered a rotational physical system that oscillates around the support beams 42A and 42B as its axis of rotation, so the center of gravity position Gr of the support beams 42A and 42B, which are the axis of rotation, is taken as the origin O. Then, the center of gravity position Gm of the movable body MB is tilted by an angle θ from the +X axis direction, because its height hm is lower than the height hr of the origin O. m =(r mx , 0, r mz It is expressed using ). Note that the r of the Z coordinate mzThis is a negative value. Also, the inertial force F acting on the movable body MB is given by the inertial force vector FI = (FI) which points in the +X direction from the origin O. x It is expressed using the position vector (x, y, z) and the force vector (F). Generally, torque T is expressed using the position vector (x, y, z) and the force vector (F). x F y F z The cross product of ) is expressed as in equation (1).

number

[0038] Therefore, the position vector r is added to equation (1). m =(r mx , 0, r mz ) and the inertial force vector FI = (FI x Substituting (0, 0), the torque T generated in the rotational physical system including the movable body MB can be calculated as shown in equation (2).

number

[0039] As mentioned above, r mz Since < 0, from equation (2), the position vector r m If the inertial force vector FI is offset by an angle θ, the torque T will have the rotation axis in the -Y direction, and r mz FI x This results in a vector with magnitude . That is, the first movable electrode group 20A and 20B of the movable body MB attempts to move in the Z direction on a circular orbit with the Y axis as the axis of rotation. Also, r in equation (2) mz FI x Using the angle θ, it can be found as shown in equation (3).

number

[0040] That is, with respect to the inertial force vector FI along the X-axis, the position vector r mIf the structure is tilted from the X-axis direction, the cross product in equation (1) will not be zero, and a torque T will always be generated. Thus, if the height hm of the center of gravity position Gm of the movable body MB and the height hr of the center of gravity position Gr of the support beams 42A and 42B are different, the cross product in the rotational physical system will not be zero, and the movable body MB will oscillate on a circular orbit centered on the support beams 42A and 42B. Consequently, the physical quantity sensor 1 will detect acceleration in a direction other than the third direction DR3, which is its intended target, as the acceleration in the third direction DR3.

[0041] The sensitivity with which a physical quantity sensor detects a physical quantity in a direction other than the one it is intended to detect as a physical quantity in the intended direction is called cross-axial sensitivity. In a physical quantity sensor, if such cross-axial sensitivity is high, it will detect physical quantities other than the intended quantity as the intended quantity, thus degrading the detection accuracy of the physical quantity sensor. Therefore, it is desirable to suppress cross-axial sensitivity as much as possible. In the above discussion, we considered the case where the mass distribution of each component of the physical quantity sensor 1 is uniform, but even if the mass distribution is non-uniform, similar results can be obtained if the positional relationship of the center of gravity is as shown in Figure 6.

[0042] The physical quantity sensor 1 disclosed in the aforementioned Patent Document 1 is a physical quantity sensor of the area-changing type with fixed electrodes and movable electrodes, similar to the physical quantity sensor 1 of this embodiment, and detects physical quantities in the Z-axis direction. However, the thickness of a part of the movable body constituting the movable electrode is designed to be thin from the viewpoint of improving the signal-to-noise ratio of the output signal. For this reason, the height in the Z-axis direction of the center of gravity of the torsion springs corresponding to the support beams 42A and 42B is different from the height in the Z-axis direction of the center of gravity of the entire movable body including the movable electrode. Consequently, as explained in Figure 6, the position vector from the center of gravity of the torsion spring corresponding to the rotation axis to the center of gravity of the movable body is deviated from the horizontal direction, generating torque T and resulting in increased sensitivity in other axes. Thus, in Patent Document 1, while the signal-to-noise ratio of the output signal can be improved by thinning the thickness of the movable electrode in the Z-axis direction, the disadvantage of increased sensitivity in other axes occurs.

[0043] Figure 7 is a schematic diagram of the cross-section of each component of the physical quantity sensor 1 when this embodiment is applied. That is, the positional relationship G of the center of gravity as explained in Figure 5. Z1 >Gm=Gr>G Z2 This is the case when the following condition is met. In this case, the position vector r from the origin O to the center of gravity Gm of the movable body MB is m It is parallel to the X-axis direction, which is the first direction DR1. In this case, the position vector r m =(r mx (0,0) and the inertial force vector FI = (FI x Substituting (0,0) into equation (1), we get the position vector r m Since all components except the x-coordinate component are zero, the torque T is zero. In other words, even if an inertial force FI acts in the x-axis direction, no torque T is generated in the rotational physical system including the movable body MB.

[0044] Furthermore, in this embodiment, by reducing the thickness of either the first movable electrode group 20A or the first movable electrode group 20B in the third direction DR3, the benefit of improving the signal-to-noise ratio of the output signal as disclosed in Patent Document 1 can also be obtained. Therefore, the physical quantity sensor 1 can achieve both an improvement in the signal-to-noise ratio of the output signal and suppression of interaxial sensitivity.

[0045] That is, the physical quantity sensor 1 of this embodiment includes fixed parts 40A, 40B, support beams 42A, 42B, a movable body MB, and first fixed electrode groups 10A, 10B. The fixed parts 40A, 40B are fixed to the substrate 2, and the support beams 42A, 42B are connected at one end to the fixed parts 40A, 40B and are provided along the second direction DR2. The movable body MB is connected to the other end of the support beams 42A, 42B, and the first fixed electrode groups 10A, 10B are provided on the substrate 2 and are arranged in the first direction DR1 of the support beams 42A, 42B. The movable body MB has first connecting parts 30A, 30B, a first base part 23, and first movable electrode groups 20A, 20B. The first connecting parts 30A and 30B are connected to the other ends of the support beams 42A and 42B and extend from the support beams 42A and 42B in the first direction DR1. The first base part 23 is connected to the first connecting parts 30A and 30B and is provided along the second direction DR2. The first movable electrode groups 20A and 20B provided on the first base part 23 face the first fixed electrodes 11A and 11B of the first fixed electrode groups 10A and 10B in the second direction DR2. When the height of the center of gravity of the movable body MB in the third direction DR3 is hm, and the height of the rotation centers of the support beams 42A and 42B in the third direction DR3 is hr, then hm = hr.

[0046] According to this embodiment, the sensitivity of the physical quantity sensor 1 in other axes is suppressed, enabling highly accurate detection of physical quantities. Furthermore, by reducing the thickness in the Z-axis direction of either the first movable electrode group 20A or the first movable electrode group 20B, the advantage of improved signal-to-noise ratio of the output signal disclosed in Patent Document 1 can be maintained.

[0047] Furthermore, in this embodiment, torsional springs are used in the support beams 42A and 42B. This allows the rigidity to be adjusted by the thickness of the third direction DR3 of the support beams 42A and 42B, making it easy to increase sensitivity without increasing the area and enabling miniaturization. In addition, since the second direction DR2 in the direction of the torsional spring length and the first direction DR1 in the direction of the comb teeth length are orthogonal, the comb teeth length of the first movable electrodes 21A and 21B does not need to be long, and problems such as impact resistance and electrode sticking together can be improved.

[0048] Furthermore, in this embodiment, the longitudinal direction of the movable body MB, that is, the longitudinal direction of the first base portion 23, is positioned to be in the same direction as the second direction DR2, which is the axis of rotation. In this way, even if a swaying motion occurs in the in-plane rotational direction of the substrate 2, the vibration frequency of the swaying motion and the frequency of the detection mode of the physical quantity sensor 1 can be kept far apart, thereby suppressing resonance phenomena. Consequently, it is possible to prevent vibrations due to the swaying mode from interfering with the detection of the physical quantity sensor 1, and also to suppress the increase in multi-axis sensitivity.

[0049] 2. Detailed Configuration Example Figure 8 is a plan view of a first detailed example of the physical quantity sensor 1 of this embodiment. The first detailed example is a physical quantity sensor of the third direction DR3 with an area-changing structure due to out-of-plane rotation using comb-tooth electrodes, similar to the physical quantity sensor 1 shown in Figure 1, but the arrangement of the detection units Z1 and Z2 differs from the configuration example shown in Figure 1. Specifically, the detection units Z1 and Z2, shown by dashed lines in Figure 8, are arranged side by side along the second direction DR2, unlike in the case shown in Figure 1. Accordingly, the physical quantity sensor 1 shown in the first detailed example has a second connecting unit 70, a second base unit 63, a second fixed electrode group 50, and a second movable electrode group 60. The second connecting unit 70, the second fixed electrode group 50, and the second movable electrode group 60 correspond to the first connecting unit 30B, the first fixed electrode group 10B, and the first movable electrode group 20B in the configuration of Figure 1, respectively. The detection unit Z1 corresponds to the N side, and the detection unit Z2 corresponds to the P side.

[0050] In the detection unit Z1, the first fixed electrode group has a first fixed electrode 11 on the fourth direction DR4 side, separated by a first base 23, and a first fixed electrode 12 on the first direction DR1 side, separated by a first base 23. Similarly, the first movable electrode group 20 has a first movable electrode 21 on the fourth direction DR4 side, separated by a first base 23, and a first movable electrode 22 on the first direction DR1 side, separated by a first base 23. In the detection unit Z2, the second fixed electrode group has a second fixed electrode 51 on the fourth direction DR4 side, separated by a second base 63, and a second fixed electrode 52 on the first direction DR1 side, separated by a second base 63. The second movable electrode group 60 has a second movable electrode 61 on the fourth direction DR4 side, separated by a second base 63, and a second movable electrode 62 on the first direction DR1 side, separated by a second base 63. In the following, the first fixed electrodes 11 and 12 will be collectively referred to as the first fixed electrode 14, the second fixed electrodes 51 and 52 as the second fixed electrode 54, the first movable electrodes 21 and 22 as the first movable electrode 24, and the second movable electrodes 61 and 62 as the second movable electrode 64, as appropriate. In the first detailed example, the first connecting portion 30 and the second connecting portion 70 are connected via the first base portion 23 and the second base portion 63.

[0051] Figure 9 is a perspective view of the first detailed example. As shown in Figure 9, the thickness of the electrode comb teeth in the third direction DR3 differs between detection units Z1 and Z2, which are positioned along the second direction DR2. In detection unit Z1, the thickness of the first fixed electrode group 10 is greater than that of the first movable electrode group 20, while in detection unit Z2, the thickness of the second fixed electrode group 50 is thinner than that of the second movable electrode group 60. Therefore, in the perspective view of Figure 9, the first movable electrode group 20 and the second fixed electrodes 51 and 52, which are thinner in the third direction DR3, are hidden and not visible.

[0052] Figure 10 shows the detailed electrode shapes of detection units Z1 and Z2 in the first detailed example. The upper part of Figure 10 shows the electrode shape of detection unit Z1. Unlike the configuration example in Figure 1, the first detailed example has equal thickness in the third direction DR3 of the first movable electrode 21 and the first movable electrode 22. The thickness of the first fixed electrode 11 and the first fixed electrode 12 is also equal. Furthermore, the ends of the first fixed electrodes 11 and 12 and the first movable electrodes 21 and 22 are offset on the +Z direction side, while the ends of the first fixed electrodes 11 and 12 and the first movable electrodes 21 and 22 are at the same position on the -Z direction side. In other words, it has a one-sided offset structure.

[0053] The lower diagram in Figure 10 shows the electrode shape of the detection unit Z2 in the first detailed example. Similar to the detection unit Z1, the thickness of the second movable electrode 61 and the second movable electrode 62 in the third direction DR3 is equal, and the thickness of the second fixed electrode 51 and the second fixed electrode 52 is also equal. Furthermore, similar to the detection unit Z1, the ends of the second fixed electrodes 51 and 52 and the second movable electrodes 61 and 62 are offset on one side only on the +Z direction side, resulting in a one-sided offset structure.

[0054] Figure 11 is a diagram illustrating the operation of the first detailed example. The operating principle in the first detailed example is the same as the method described in Figure 4, where a physical quantity is detected when the opposing area of ​​the comb-shaped electrodes decreases in either the detection unit Z1 or Z2 in response to acceleration in the +Z or -Z direction. In Figure 11, when acceleration in the third direction DR3 occurs, the first movable electrode group 20 in the detection unit Z1 receives an inertial force in the fifth direction DR5, i.e., the -Z direction, and is displaced in the -Z direction. As a result, the opposing area between the first fixed electrode 14 and the first movable electrode 24 decreases. On the other hand, in the detection unit Z2, even if the second movable electrode group 60 is displaced in the -Z direction due to the same inertial force, the opposing area does not change. Therefore, the acceleration in the third direction DR3 can be detected by the decrease in the opposing area in the detection unit Z1. When acceleration occurs in the fifth direction DR5, i.e., the -Z direction, in the detection unit Z1, the first movable electrode group 20 is displaced in the +Z direction due to an inertial force in the +Z direction, but the opposing area between the first fixed electrode 14 and the first movable electrode 24 does not change. On the other hand, in the detection unit Z2, the second movable electrode group 60 is displaced in the +Z direction due to the same inertial force, so the opposing area between the second fixed electrode 54 and the second movable electrode 64 decreases. In the first detailed example, the detection unit Z1 corresponds to the N side of the probe, and the detection unit Z2 corresponds to the P side of the probe.

[0055] That is, as shown in Figure 8, in this embodiment, the physical quantity sensor 1 is provided on the substrate 2 and includes a second fixed electrode group 50 positioned in the first direction DR1 of the support beams 42A and 42B. The movable body MB includes a second connecting portion 70, a second base portion 63, and a second movable electrode group 60. The second connecting portion 70 is connected to the other ends of the support beams 42A and 42B and extends from the support beams 42A and 42B in the first direction DR1. The second base portion 63 is connected to the second connecting portion 70 and is provided along the second direction DR2. The second movable electrode group 60 is provided on the second base portion 63 and faces the second fixed electrodes 51 and 52 of the second fixed electrode group 50 in the second direction DR2.

[0056] In this way, the physical quantity sensor 1 can be equipped with two detection units Z1 and Z2, and the detection units Z1 and Z2 can be arranged side by side along the second direction DR2, which is the axis of rotation of the oscillating motion of the movable body MB.

[0057] In this embodiment, the first movable electrode group 20 and the second movable electrode group 60 are arranged along the second direction DR2 between the first connecting portion 30 and the second connecting portion 70.

[0058] In this way, detection units Z1 and Z2 can be provided between the first connecting portion 30 and the second connecting portion 70 of the physical quantity sensor 1 in a plan view, along the second direction DR2.

[0059] Furthermore, as shown in Figure 7, in this embodiment, when the height of the center of gravity of the first movable electrode group 20 in the third direction DR3 is hm1 and the height of the center of gravity of the second movable electrode group 60 in the third direction DR3 is hm2, then hm2 > hr > hm1.

[0060] In this way, the height of the center of gravity Gm of the movable body MB and the height of the center of gravity of the support beams 42A and 42B in the third direction DR3 can be made to match, while the thickness of the second movable electrode group 60 in the third direction DR3 can be made to be greater than the thickness of the rotation center of the support beams 42A and 42B in the third direction DR3.

[0061] Furthermore, in this embodiment, the thickness of the second movable electrode group 60 in the third direction DR3 is greater than the thickness of the first movable electrode group 20 in the third direction DR3.

[0062] In this way, in the detection unit Z1, it becomes easy to make the thickness of the first movable electrode group 20 in the third direction DR3 thinner than the thickness of the first fixed electrode group 10 in the third direction DR3. Similarly, in the detection unit Z2, it becomes easy to make the thickness of the second movable electrode group 60 in the third direction DR3 thicker than the thickness of the second fixed electrode group 50 in the third direction DR3.

[0063] Furthermore, in this embodiment, in the initial state, the back surface position of the first movable electrode group 20 in the third direction DR3 coincides with the back surface position of the second movable electrode group 60 in the third direction DR3.

[0064] In this way, the probe of the comb-shaped electrode, consisting of the first fixed electrodes 11 and 12 and the first movable electrodes 21 and 22, can be made to have a one-sided offset shape with an offset in the third direction DR3. Similarly, the probe of the comb-shaped electrode, consisting of the second fixed electrodes 51 and 52 and the second movable electrodes 61 and 62, can be made to have a one-sided offset shape with an offset in the third direction DR3.

[0065] Figure 12 is a plan view of a second detailed example of the physical quantity sensor 1 of this embodiment. The arrangement pattern of the detection units Z1 and Z2 differs from that of the first detailed example. Specifically, as shown in Figure 12, in a plan view in the third direction DR3, the detection units are arranged in the order of detection unit Z2, detection unit Z1, and detection unit Z2 from the second direction DR2 side. In this way, multiple detection units Z1 and Z2 can be provided and arranged alternately along the second direction DR2.

[0066] Figure 13 is a perspective view of the second detailed example. Except for the arrangement pattern of the detection units Z1 and Z2, it is the same as in Figure 9. Comparing the second detailed example with the first detailed example, the mass distribution is arranged symmetrically with respect to the X-axis, indicated by the dashed line in Figure 13. Therefore, according to the second detailed example, when acceleration in the third direction DR3 occurs, the variation in the displacement of the movable body MB in the third direction DR3 can be suppressed. Consequently, the detection accuracy of the physical quantity sensor 1 can be improved. Furthermore, since various variations in the arrangement pattern of the detection units Z1 and Z2 are possible, the optimal arrangement pattern can be selected according to the space available for arranging the comb-shaped electrodes of the physical quantity sensor 1.

[0067] Several configurations can be considered as variations of the first detailed example which adopts a one-sided offset structure. For example, in Figure 14, the thickness of the first fixed electrode 14 of the detection unit Z1 and the second movable electrode 64 of the detection unit Z2 may be different, and the thickness of the first movable electrode 24 of the detection unit Z1 and the second fixed electrode 54 of the detection unit Z2 may be different. The thickness of the movable body MB may also be smaller or larger than the thickness of the first movable electrode 24 of the detection unit Z1. Here, the thickness of the support beams 42A and 42B, which are torsion springs, is in a range that is thicker than the thinnest thickness and thinner than the thickest thickness among the thicknesses of the movable body MB and the movable electrodes of the detection units Z1 and Z2. In addition, although the first and second detailed examples were described above using a configuration in which only the back surface of the comb-tooth electrode is flush as an example, only the front surface may be flush. As explained in Figure 7, all of the above modifications are acceptable as long as the position of the center of gravity Gm of the movable body MB in the third direction coincides with the position of the center of gravity Gr of the support beams 42A and 42B in the third direction DR3. As long as the positional relationship of the centers of gravity is such, the configuration of this embodiment is not limited to those described above.

[0068] Furthermore, in the first and second detailed examples, the comb-shaped electrodes of the detection units Z1 and Z2 were offset on one side, but they can also be offset on both sides. Figure 14 is a schematic diagram showing the configuration of the comb-shaped electrode portion in the third detailed example, in which the comb-shaped electrodes of the first and second detailed examples are offset on both sides. The upper part of Figure 14 shows the shape of the comb-shaped electrode in the detection unit Z1, and the lower part shows the shape of the comb-shaped electrode in the detection unit Z2.

[0069] In detection unit Z1, the first movable electrodes 21 and 22 are offset towards the third direction DR3 compared to the first fixed electrodes 11 and 12. When viewed from the second direction DR2, the first fixed electrode 11 overlaps with the first movable electrode 21, and the first fixed electrode 12 overlaps with the first movable electrode 22, and a portion of the first fixed electrode 12 overlaps with the first movable electrode 22. In this way, the comb-shaped electrodes of detection unit Z1 are offset on both sides. In detection unit Z2, the second movable electrodes 61 and 62 are offset towards the fifth direction DR5 compared to the second fixed electrodes 51 and 52. When viewed from the second direction DR2, the second fixed electrode 51 overlaps with the second movable electrode 61, and a portion of the second fixed electrode 52 overlaps with the second movable electrode 62. In this way, the comb-shaped electrodes of detection unit Z2 are also offset on both sides.

[0070] The positional relationship of each component in the third detailed example in the third direction DR3 will be supplemented below. Here, the surface on the third direction DR3 side will be referred to as the front surface, and the surface on the fifth direction DR5 side will be referred to as the back surface. In the detection unit Z1, the front and back surfaces of the first movable electrode 24 are located in the +Z direction relative to the front and back surfaces of the first fixed electrode 14, respectively. In the detection unit Z2, the opposite is true, where the front and back surfaces of the second movable electrode 64 are located in the -Z direction relative to the front and back surfaces of the second fixed electrode 54. The front and back surfaces of the first movable electrode 24 in the detection unit Z1 and the front and back surfaces of the second fixed electrode 54 in the detection unit Z2 are flush, and the electrode thicknesses are the same. The front and back surfaces of the first fixed electrode 14 in the detection unit Z1 and the second movable electrode 64 in the detection unit Z2 are also flush, and have the same thickness. Furthermore, the offset amount in the third direction DR3 between the surface of the first movable electrode 24 and the surface of the first fixed electrode 14 of the detection unit Z1 is equal to the offset amount in the fifth direction DR5 between the back surface of the second movable electrode 64 and the back surface of the second fixed electrode 54 of the detection unit Z2. The surfaces of the first connecting portion 30 and the second connecting portion 70 of the movable body MB are flush with the surfaces of the first movable electrode 24 of the detection unit Z1 and the second fixed electrode 54 of the detection unit Z2. The back surfaces of the first connecting portion 30 and the second connecting portion 70 of the movable body MB are flush with the back surfaces of the first fixed electrode 14 of the detection unit Z1 and the second movable electrode 64 of the detection unit Z2. The front and back surfaces of the torsion spring support beams 42A and 42B coincide with the front and back surfaces of the movable body MB.

[0071] Figure 15 is a diagram illustrating the operation of the physical quantity sensor 1 to which the third detailed example is applied. Similar to the explanatory diagram of operation described in Figure 4, the movement of the comb-tooth electrodes in the initial state and the state in which acceleration is applied is shown. In the third detailed example to which the double-sided offset shape is applied, the movable body MB rotates out of plane around the support beams 42A and 42B as the axis of rotation, and the opposing area of ​​the comb-tooth electrodes increases in either the detection unit Z1 or Z2, while decreasing in the other. That is, unlike the configuration example in Figure 1, the first detailed example, and the second detailed example described so far, the opposing area of ​​the comb-tooth electrodes changes regardless of whether the first movable electrode 24 or the second movable electrode 64 is displaced in the third direction DR3 or the fifth direction DR5, so the detection sensitivity of the physical quantity is doubled compared to the configuration example in Figure 1, etc. Therefore, it is advantageous in terms of increasing the sensitivity of physical quantity detection compared to the configuration example to which the single-sided offset shape is applied.

[0072] In other words, in this embodiment, the thickness of the first movable electrode group 20 in the third direction DR3 is equal to the thickness of the second movable electrode group 60 in the third direction DR3. Also, in this embodiment, in the initial state, the back surface position of the first movable electrode group 20 in the third direction DR3 and the back surface position of the second movable electrode group 60 in the third direction DR3 do not coincide.

[0073] In this way, the probe of the comb-shaped electrode, consisting of the first fixed electrodes 11 and 12 and the first movable electrodes 21 and 22, can be made into a double-sided offset shape with offsets in both the third direction DR3 and the fifth direction DR5. Similarly, the probe of the comb-shaped electrode, consisting of the second fixed electrodes 51 and 52 and the second movable electrodes 61 and 62, can be made into a double-sided offset shape with offsets in both the third direction DR3 and the fifth direction DR5.

[0074] Figure 16 is a schematic cross-sectional view showing the positional relationship of the center of gravity of each component in the third detailed example in which a double-sided offset shape is applied. As explained in Figure 5, in this embodiment, the center of gravity of each component of the physical quantity sensor 1 is G Z1 >Gm=Gr>G Z2 By designing it to have this relationship, torque is prevented from being generated for accelerations in the first direction DR1 other than the third direction DR3, thereby reducing sensitivity to other axes.

[0075] In this regard, in the third detailed example, as shown on the left side of Figure 16, when viewed from the second direction DR2, the first movable electrode 24 and the second movable electrode 64 overlap in part, and are shifted by the same length in the third direction DR3 and the fifth direction DR5, respectively. From this positional relationship of the comb-shaped electrodes, it becomes easy to align the center of gravity of the movable part and the support beams 42A and 42B in the third direction. For example, by making the positions of the support beams 42A and 42B, the movable part, and the first movable electrode 24 equal in the third direction DR3, and the positions of the support beams 42A and 42B, the movable part, and the second movable electrode 64 equal in the fifth direction DR5, G inevitably becomes Z1 >Gm=Gr>G Z2 This positional relationship can be achieved.

[0076] Figure 17 is a schematic diagram of the cross-section of each component of the physical quantity sensor 1 to which the third detailed example is applied. As described above, G Z1 >Gm=Gr>G Z2 This positional relationship is achieved, and the height hm of the center of gravity of the movable body MB in the third direction DR3 is equal to the height hr of the center of gravity of the support beams 42A and 42B in the third direction DR3. Therefore, the position vector r m This becomes parallel to the first direction DR1. Therefore, as explained in Figure 7, even if the inertial force FI in the first direction DR1 acts on the physical quantity sensor 1, it will not affect the oscillating motion of the movable body MB with the support beams 42A and 42B as the axis of rotation, thereby improving the multi-axis sensitivity of the physical quantity sensor 1.

[0077] As mentioned above, in the third detailed example as well, the center of gravity of each component is G Z1 >Gm=Gr>G Z2The following positional relationship is established. That is, the position of the centroid Gm in the thickness direction in the third direction DR3 of the movable body MB and the position of the centroid Gr in the thickness direction in the third direction DR3 of the support beams 42A and 42B coincide in the third direction DR3. Several modifications having such a positional relationship of the centroid can be considered in the third detailed example. Figure 18 shows variations of the third detailed example other than the comb-tooth electrode configuration shown in Figures 14 and 15. As shown in Figure 18, four variations can be considered depending on the number of contour lines indicating the positions in the third direction DR3 of the first fixed electrode 14 and first movable electrode 24 of the detection unit Z1, and the second fixed electrode 54 and second movable electrode 64 of the detection unit Z2. The comb-tooth shape pattern shown on the left of the upper row is a pattern in which the positions of all the front and back surfaces of the first fixed electrode 14, second fixed electrode 54, first movable electrode 24, and second movable electrode 64 are shifted, and it has the most contour lines. The number of contour lines decreases in the order of the center, right, and bottom of the upper row. The shape pattern with the fewest contour lines is the configuration shown in Figure 14.

[0078] In addition, variations in the positional relationship between the movable body MB and the support beams 42A and 42B are also possible. For example, there are cases where the surface of the movable body MB is not flush with the surface of the first movable electrode 24 of the detection unit Z1 and the second fixed electrode 54 of the detection unit Z2, or where the back surface of the movable body MB is not flush with the back surface of the first fixed electrode 14 of the detection unit Z1 and the second fixed electrode 54 of the detection unit Z2. It is also possible that the front and back surfaces of the support beams 42A and 42B are not flush with either one side or both sides of the movable body MB. In this case, the thickness of the support beams 42A and 42B in the third direction is irrelevant; a smaller thickness results in a larger displacement, which is advantageous as it allows for higher sensitivity in detecting physical quantities.

[0079] 3. Inertial measurement device Next, an example of the inertial measurement device 2000 of this embodiment will be described using Figures 19 and 20. The inertial measurement device 2000 (IMU) shown in Figure 19 is a device that detects inertial momentum such as the attitude and behavior of a moving object such as an automobile or a robot. The inertial measurement device 2000 is a so-called 6-axis motion sensor equipped with acceleration sensors that detect accelerations ax, ay, and az in the direction along three axes, and angular velocity sensors that detect angular velocities ωx, ωy, and ωz around three axes.

[0080] The inertial measuring device 2000 is a rectangular prism with a roughly square shape in plan view. Screw holes 2110, which serve as mounting points, are formed near two vertices located diagonally across the square. The inertial measuring device 2000 can be fixed to the mounting surface of an object such as an automobile by passing two screws through these two screw holes 2110. Furthermore, by selecting components and modifying the design, it is possible to miniaturize the device to a size that can be mounted on, for example, a smartphone or digital camera.

[0081] The inertial measuring device 2000 comprises an outer case 2100, a connecting member 2200, and a sensor module 2300. The sensor module 2300 is inserted into the outer case 2100 with the connecting member 2200 interposed between them. The sensor module 2300 comprises an inner case 2310 and a circuit board 2320. The inner case 2310 has a recess 2311 to prevent contact with the circuit board 2320 and an opening 2312 to expose a connector 2330, which will be described later. The circuit board 2320 is bonded to the lower surface of the inner case 2310 via adhesive.

[0082] As shown in Figure 20, the top surface of the circuit board 2320 is equipped with a connector 2330, an angular velocity sensor 2340z for detecting angular velocity around the Z axis, and an acceleration sensor unit 2350 for detecting acceleration in the X, Y, and Z axes. Additionally, the sides of the circuit board 2320 are equipped with an angular velocity sensor 2340x for detecting angular velocity around the X axis and an angular velocity sensor 2340y for detecting angular velocity around the Y axis.

[0083] The acceleration sensor unit 2350 includes at least the physical quantity sensor 1 for measuring acceleration in the Z-axis direction as described above, and can detect acceleration in one axis direction, or acceleration in two or three axes as needed. The angular velocity sensors 2340x, 2340y, and 2340z are not particularly limited, but for example, a vibration gyro sensor utilizing the Coriolis force can be used.

[0084] Furthermore, a control IC 2360 is mounted on the underside of the circuit board 2320. The control IC 2360, which acts as a control unit that performs control based on the detection signal output from the physical quantity sensor 1, is, for example, an MCU (Micro Controller Unit), and incorporates a storage unit including non-volatile memory and an A / D converter, and controls various parts of the inertial measurement device 2000. In addition, several other electronic components are mounted on the circuit board 2320.

[0085] As described above, the inertial measurement device 2000 of this embodiment includes a physical quantity sensor 1 and a control IC 2360 which acts as a control unit that performs control based on the detection signal output from the physical quantity sensor 1. With this inertial measurement device 2000, since an acceleration sensor unit 2350 including the physical quantity sensor 1 is used, the effects of the physical quantity sensor 1 can be enjoyed, and an inertial measurement device 2000 that can achieve high accuracy and the like can be provided.

[0086] The inertial measurement device 2000 is not limited to the configurations shown in Figures 19 and 20. For example, the inertial measurement device 2000 may be configured to include only the physical quantity sensor 1 as an inertial sensor, without the angular velocity sensors 2340x, 2340y, and 2340z. In this case, the inertial measurement device 2000 can be realized by housing the physical quantity sensor 1 and the control IC 2360, which implements the control unit, in a package that serves as a housing.

[0087] As described above, the physical quantity sensor of this embodiment includes a fixed part, a support beam, a movable body MB, and a first fixed electrode group. The fixed part is fixed to a substrate, and the support beam is connected to the fixed part at one end and is provided along a second direction. The movable body is connected to the other end of the support beam, and the first fixed electrode group is provided on the substrate and is arranged in the first direction of the support beam. The movable body has a first connecting part, a first base part, and a first movable electrode group. The first connecting part is connected to the other end of the support beam and extends from the support beam in a first direction, the first base part is connected to the first connecting part and is provided along a second direction, and the first movable electrode group provided on the first base part faces the first fixed electrode group in the second direction. When the height of the center of gravity of the movable body in a third direction is hm, and the height of the center of rotation of the support beam in a third direction is hr, then hm = hr.

[0088] According to this embodiment, even if acceleration occurs in the first direction, the resulting inertial force and the position vector from the support beam to the center of gravity of the movable body are parallel, so no torque is generated. Therefore, it is possible to prevent physical quantities in the first direction other than the third direction, which is the target of detection, from being detected as physical quantities in the third direction. Thus, according to this embodiment, the multi-axis sensitivity of the physical quantity sensor is suppressed, and highly accurate detection of physical quantities becomes possible.

[0089] In this embodiment, the movable body includes a second fixed electrode group provided on the substrate and arranged in a first direction of the support beam, a second connecting portion connected to the other end of the support beam and extending from the support beam in a first direction, a second base portion connected to the second connecting portion and provided along a second direction, and a second movable electrode group provided on the second base portion and facing the second fixed electrode group in a second direction.

[0090] In this way, the physical quantity sensor 1 can be equipped with two detection units, and the two detection units can be arranged side by side along the second direction which becomes the axis of rotation of the oscillating motion of the movable body.

[0091] In this embodiment, the first movable electrode group and the second movable electrode group are arranged along the second direction between the first connecting portion and the second connecting portion.

[0092] In this way, two detection units can be provided between the first and second connecting parts of the physical quantity sensor in a plan view, along the second direction.

[0093] In this embodiment, when the height of the center of gravity of the first movable electrode group in the third direction is hm1 and the height of the center of gravity of the second movable electrode group in the third direction is hm2, then hm2 > hr > hm1.

[0094] In this way, the height of the center of gravity of the movable body and the center of gravity of the support beam in the third direction can be made to coincide, while the thickness of the second movable electrode group in the third direction can be made thicker than the thickness of the support beams 42A and 42B in the third direction DR3 of the rotation center.

[0095] Furthermore, in this embodiment, the thickness of the second movable electrode group in the third direction is greater than the thickness of the first movable electrode group in the third direction.

[0096] In this way, in a detection unit including a first movable electrode group, it becomes easy to make the thickness of the first movable electrode group in the third direction thinner than the thickness of the first fixed electrode group in the third direction. Also, in a detection unit including a second movable electrode group, it becomes easy to make the thickness of the second movable electrode group in the third direction thicker than the thickness of the second fixed electrode group in the third direction.

[0097] Furthermore, in this embodiment, in the initial state, the back surface position of the first movable electrode group in the third direction coincides with the back surface position of the second movable electrode group in the third direction.

[0098] In this way, the comb-shaped electrode consisting of the first fixed electrode and the first movable electrode can be made into a one-sided offset shape with an offset in the third direction. Similarly, the comb-shaped electrode consisting of the second fixed electrode and the second movable electrode can be made into a one-sided offset shape with an offset in the third direction DR3.

[0099] In this embodiment, the thickness of the first movable electrode group in the third direction is equal to the thickness of the second movable electrode group in the third direction.

[0100] Furthermore, in this embodiment, in the initial state, the back surface position of the first movable electrode group in the third direction does not coincide with the back surface position of the second movable electrode group in the third direction.

[0101] In this way, the comb-shaped electrode consisting of the first fixed electrode and the second movable electrode can be made into a double-sided offset shape with offsets in both the third and fifth directions. Similarly, the comb-shaped electrode consisting of the second fixed electrode and the second movable electrode can be made into a double-sided offset shape with offsets in both the third and fifth directions.

[0102] Thus, in this embodiment, the support beam is a torsion spring that twists with the second direction as its axis of rotation. In this way, the movable body can perform a rocking motion with the second direction as its axis of rotation.

[0103] This embodiment also relates to an inertial measuring device that includes a control unit that performs control based on detection signals output from a physical quantity sensor.

[0104] Although this embodiment has been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novelty and effects of this disclosure. Therefore, all such modifications are included within the scope of this disclosure. For example, any term that appears at least once in the specification or drawings together with a broader or synonymous term may be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of this embodiment and its modifications are also included within the scope of this disclosure. In addition, the configuration and operation of the physical quantity sensor and inertial measuring device are not limited to those described in this embodiment, and various modifications are possible. [Explanation of symbols]

[0105] 1...Physical quantity sensor, 2...Substrate, 10...First fixed electrode group, 10A...First fixed electrode group, 10B...First fixed electrode group, 11...First fixed electrode, 11A...First fixed electrode, 11B...First fixed electrode, 12...First fixed electrode, 14...First fixed electrode, 20...First movable electrode group, 20A...First movable electrode group, 20B...First movable electrode group, 21...First movable electrode, 2 1A...first movable electrode, 21B...first movable electrode, 22...first movable electrode, 23...first base, 24...first movable electrode, 30...first connecting part, 30A...first connecting part, 30B...first Connecting part, 40A...Fixed part, 40B...Fixed part, 42A...Support beam, 42B...Support beam, 50...Second fixed electrode group, 51...Second fixed electrode, 52...Second fixed electrode, 54...Second fixed Electrode, 60…Second movable electrode group, 61…Second movable electrode, 62…Second movable electrode, 63…Second base, 64…Second movable electrode, 70…Second connecting part, 2000…Inertial measurement device, 2100…Outer case, 2110…Screw hole, 2200…Jointing member, 2300…Sensor module, 2310…Inner case, 2311…Recess, 2312…Opening, 2320…Circuit board, 2330…Connector, 2340x…Angular velocity sensor, 2340y…Angular velocity sensor, 2340z…Angular velocity sensor, 2350…Accelerometer unit, DR…Fifth direction, DR1…First direction, DR2…Second direction, DR3…Third direction, DR4…Fourth direction, DR5…Fifth direction, F…Inertial force, FI…Inertial force, FI x ...x-component of inertial force, FI y...y component of inertial force, FI z ...z component of inertial force, G Z1 ...center of gravity position, G Z2 ...Center of gravity position, Gm...Center of gravity position, G r ...center of gravity, IC2360...control, MB...movable body, O...origin, T...torque, Z1...detection unit, Z2...detection unit, ax...acceleration, ay...acceleration, az...acceleration, hm...height, hr...height, r m ...position vector, r mx ...position vector x component, r my ...position vector y component, r mz ...Position vector z component, θ...Angle, ω x ...angular velocity, ω y ...angular velocity, ω z …angular velocity

Claims

1. A physical quantity sensor that detects acceleration as a physical quantity in the third direction, when three mutually orthogonal directions are designated as the first direction, the second direction, and the third direction, A fixing part fixed to the circuit board, A support beam including a first support beam, one end of which is connected to the fixed portion and provided along the second direction, and a second support beam, one end of which is connected to the fixed portion and provided along the second direction, A movable body connected to the other end of the support beam, A group of first fixed electrodes provided on the substrate and arranged in the first direction of the first support beam, A second group of fixed electrodes is provided on the substrate and is arranged in the first direction of the second support beam, Includes, The aforementioned movable body is A first connecting portion connected to the other end of the first support beam and extending from the first support beam in the first direction, A second connecting portion connected to the other end of the second support beam and extending from the second support beam in the first direction, A first base portion connected to the first connecting portion and provided along the second direction, A second base portion connected to the second connecting portion and provided along the second direction, The first base is provided with the first fixed electrode group and the first movable electrode group whose electrode surfaces face each other with the second direction as the normal, The second base is provided with the second fixed electrode group and the second movable electrode group, whose electrode surfaces face each other with the second direction as the normal, It has, When the height of the center of gravity of the movable body in the third direction is hm, and the height of the rotation center of the support beam in the third direction is hr, hm = hr, When the height of the center of gravity of the first movable electrode group in the third direction is hm1, and the height of the center of gravity of the second movable electrode group in the third direction is hm2, A physical quantity sensor characterized by hm2 > hr > hm1.

2. In the physical quantity sensor according to claim 1, A physical quantity sensor characterized in that the first movable electrode group and the second movable electrode group are arranged between the first connecting portion and the second connecting portion along the second direction.

3. In the physical quantity sensor according to claim 1, A physical quantity sensor characterized in that the thickness of the second movable electrode group in the third direction is greater than the thickness of the first movable electrode group in the third direction.

4. In the physical quantity sensor described in claim 3, A physical quantity sensor characterized in that, in the initial state, the back surface position of the first movable electrode group in the third direction coincides with the back surface position of the second movable electrode group in the third direction.

5. In the physical quantity sensor according to claim 1, A physical quantity sensor characterized in that the thickness of the first movable electrode group in the third direction is equal to the thickness of the second movable electrode group in the third direction.

6. In the physical quantity sensor according to claim 5, A physical quantity sensor characterized in that, in its initial state, the back surface position of the first movable electrode group in the third direction and the back surface position of the second movable electrode group in the third direction do not coincide.

7. In a physical quantity sensor according to any one of claims 1 to 6, The physical quantity sensor is characterized in that the support beam is a torsion spring that twists with the second direction as its axis of rotation.

8. A physical quantity sensor according to any one of claims 1 to 6, A control unit that performs control based on the detection signal output from the physical quantity sensor, An inertial measuring device characterized by including [a certain element].

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