Physical quantity sensors and inertial measurement devices

Abstract

To provide a physical quantity sensor with high detection accuracy and an inertial measurement device while suppressing cross-axis sensitivity.SOLUTION: In a first direction of a physical quantity sensor, a first movable electrode group, a second movable electrode group, a third movable electrode group, and a fourth movable electrode group are arranged in this order. The thicknesses of each movable electrode in the second movable electrode group and each movable electrode in the third movable electrode group are different from the thicknesses of each movable electrode in the first movable electrode group and each movable electrode in the fourth movable electrode group. When a virtual line extending from the center of a stationary section to a second direction is regarded as a symmetric axis, each movable electrode in the first movable electrode group is axial-symmetrically arranged with each movable electrode in the fourth movable electrode group, and each movable electrode in the second movable electrode group is axial-symmetrically arranged with each movable electrode in the third movable electrode group.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a physical quantity sensor and an inertial measurement device including the physical quantity sensor.

Background Art

[0002] As an example of a physical quantity sensor, an acceleration sensor and an angular velocity sensor using silicon MEMS (Micro Electro Mechanical System) technology have been developed. For example, Patent Document 1 discloses a capacitive microelectromechanical acceleration sensor including a proof mass that is a partially movable frame. According to this document, when the sensor receives an acceleration in the direction of the sensing axis, the proof mass moves in the direction of the sensing axis, and the acceleration in the Z-axis direction, for example, is measured based on the change in the capacitance between the rotor measurement plate and the stator measurement plate at that time. Here, the rotor measurement plate corresponds to a movable electrode, and the stator measurement plate corresponds to a fixed electrode.

[0003] In such an acceleration sensor, when the thicknesses of the movable electrode and the fixed electrode in the Z direction are the same, the same capacitance change occurs whether the proof mass as a movable body moves in the +Z direction or in the -Z direction, and there is a problem that it is difficult to discriminate between the positive and negative directions on the detection axis. To solve this problem, it is possible to discriminate between the positive and negative directions on the detection axis by thinning the thickness of the movable electrode in some detection units and thinning the thickness of the fixed electrode in other detection units. Although Patent Document 1 describes that either the rotor measurement plate or the stator measurement plate may be recessed in the vertical direction such that the upper or lower edge of the rotor measurement plate is located at a different Z coordinate, there is no description of discriminating between the positive and negative directions on the detection axis.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] However, when the thickness of the movable and fixed electrodes was modified, the weight balance of the movable body was disrupted, causing twisting and distortion, which led to problems such as increased sensitivity in other axes and a decrease in detection accuracy. [Means for solving the problem]

[0006] A physical quantity sensor according to one embodiment of the present invention is a physical quantity sensor that detects a physical quantity in the third direction when the mutually orthogonal directions are defined as the first direction, second direction, and third direction, and comprises a fixed part fixed to a base, a support beam with one end connected to the fixed part, a fixed electrode part provided on the base and having a first fixed electrode group, a second fixed electrode group, a third fixed electrode group, and a fourth fixed electrode group, a first movable electrode group in which each movable electrode faces each fixed electrode of the first fixed electrode group, a second movable electrode group in which each movable electrode faces each fixed electrode of the second fixed electrode group, a third movable electrode group in which each movable electrode faces each fixed electrode of the third fixed electrode group, and a fourth movable electrode group in which each movable electrode faces each fixed electrode of the fourth fixed electrode group. The device includes a movable electrode section containing four movable electrode groups and a movable body having the movable electrode section, wherein in the first direction, the first movable electrode group, the second movable electrode group, the third movable electrode group, and the fourth movable electrode group are arranged in this order, the thickness of each movable electrode in the second movable electrode group and each movable electrode in the third movable electrode group differs from the thickness of each movable electrode in the first movable electrode group and each movable electrode in the fourth movable electrode group, and with respect to an imaginary line extending in the second direction from the center of the fixed part as the axis of symmetry, each movable electrode in the first movable electrode group is arranged symmetrically with respect to each movable electrode in the fourth movable electrode group, and each movable electrode in the second movable electrode group is arranged symmetrically with respect to each movable electrode in the third movable electrode group.

[0007] An inertial measuring device according to one embodiment of the present invention includes a physical quantity sensor as 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]

[0008] [Figure 1] A plan view of the acceleration sensor according to Embodiment 1. [Figure 2] Cross-sectional view of the accelerometer in section bb of Figure 1. [Figure 3] A perspective view showing the three-dimensional shape of the electrode group. [Figure 4] A perspective view showing the three-dimensional shape of the electrode group. [Figure 5] An explanatory diagram of the principle of acceleration detection. [Figure 6] A plan view of the accelerometer used in the comparative example. [Figure 7] A plan view of the sensor element according to Embodiment 2. [Figure 8] A plan view of the sensor element according to Embodiment 3. [Figure 9] A plan view of the sensor element according to Embodiment 4. [Figure 10] A plan view of the sensor element according to Embodiment 5. [Figure 11] Diagram illustrating the acceleration detection principle according to Embodiment 6. [Figure 12] An exploded perspective view of the inertial measuring device according to Embodiment 7. [Figure 13] Perspective view of the circuit board. [Modes for carrying out the invention]

[0009] Embodiment 1 ***Configuration of physical quantity sensors*** Figure 1 is a plan view of the acceleration sensor according to Embodiment 1. Figure 2 is a cross-sectional view of the acceleration sensor in the bb section of Figure 1. First, as an example of a physical quantity sensor according to this embodiment, we will explain using the acceleration sensor 100 shown in Figures 1 and 2. The acceleration sensor 100 is, for example, an acceleration sensor that detects acceleration in the vertical direction. Each figure shows the three mutually orthogonal axes, the X axis, Y axis, and Z axis. In this embodiment, the Z axis direction is defined as the vertical direction, but this is not the only definition. The positive direction of the X axis is also called the first direction, the positive direction of the Y axis is called the second direction, and the positive direction of the Z axis is called the third direction. The positive and negative directions together are also called the X direction, Y direction, and Z direction. A physical quantity sensor is also called an inertial sensor.

[0010] The accelerometer 100 is a single-axis accelerometer made of a MEMS device. The acceleration sensor 100 consists of a base body 1, a sensor element 50 placed on the base body 1, and a cover 5 that covers the sensor element 50. The substrate 1 may be, for example, a silicon substrate made of semiconductor silicon, or a glass substrate made of a glass material such as borosilicate glass. However, it is not limited to these materials, and a quartz substrate or an SOI (Silicon On Insulator) substrate formed by direct wafer bonding may also be used.

[0011] As shown in Figure 2, the substrate 1, which is made of an SOI substrate, is provided with a recess 1b that is carved out from the periphery. The recess 1b is a part that forms a storage space S for housing the sensor element 50. The recess 1b is provided with a protruding mounting portion 14 that extends from the bottom surface of the recess 1b. The mounting portion 14 is fixed to the fixing portion 3 of the sensor element 50 via the embedded insulating layer 2. In other words, the sensor element 50 is fixed to the base 1 at the fixing portion 3. In a preferred example, the fixing portion 3 is directly joined to the mounting portion 14. The sensor element 50 is formed by, for example, etching and patterning a conductive silicon substrate doped with impurities such as phosphorus (P), boron (B), arsenic (As), etc. In a preferred example, the sensor element 50 processed using deep etching technology by the Bosch process is used.

[0012] The lid 5 preferably uses a silicon substrate. Note that a glass substrate or a ceramic substrate may also be used. The lid 5 is provided with a recess 5b dug from the peripheral portion. The recess 5b is a part that forms a storage space S for storing the sensor element 50. The base 1 and the lid 5 are joined via a glass frit 13 made of a low melting point glass in a preferred example. Note that the joining method may be anodic bonding, or activation bonding, diffusion bonding, metal eutectic bonding, etc. may also be used. In a preferred example, the storage space S is filled with an inert gas such as nitrogen, helium, or argon and is hermetically sealed. It is preferable that the inside of the storage space S is at approximately atmospheric pressure in a use temperature environment of about -40°C to 120°C.

[0013] As shown in FIG. 1, the sensor element 50 is composed of a fixed portion 3, a movable body 8, a first torsion spring 4a, a second torsion spring 4b, etc. as support beams that connect the fixed portion 3 and the movable body 8. The movable body 8 is provided so as to be swingable around a swing axis 61 passing through the center of the fixed portion 3 and along the X-axis. The first torsion spring 4a is a first support beam, one end of which is fixed to the fixed portion 3 and extends in the first direction (X plus direction). The second torsion spring 4b is a second support beam, one end of which is fixed to the fixed portion 3 and extends in the X minus direction opposite to the first direction. In other words, the support beam has a first torsion spring 4a, one end of which is fixed to the fixed portion 3 and extends in the first direction, and a second torsion spring 4b, one end of which is fixed to the fixed portion 3 and extends in the direction opposite to the first direction. The first torsion spring 4a and the second torsion spring 4b are torsion springs in a preferred example and are provided on both sides of the fixed portion 3. In a preferred example, the first torsion spring 4a, the fixed portion 3, and the second torsion spring 4b are integrated and arranged on the swing axis 61.

[0014] The movable body 8 has a first connecting portion 6a extending in the positive direction of the Y-axis from the other end of the first rotating spring 4a, a second connecting portion 6b extending in the positive direction of the Y-axis from the other end of the second rotating spring 4b, and a base portion 7 which is a beam connecting the first connecting portion 6a and the second connecting portion 6b. In the preferred example, the movable body 8 is configured such that the mass of the base portion 7 at the tip is large. In other words, the mass of the base portion 7 is larger than that of the first connecting portion 6a and the second connecting portion 6b. This is to increase the moment of inertia about the pivot axis 61. In other words, the movable body 8 has one end connected to the other end of the first rotating spring 4a and extends in the second direction (Y axis A first connecting portion 6a extending in the positive direction, a second connecting portion 6b having one end connected to the other end of the second rotating spring 4b and extending in the second direction, and a connecting portion connecting the first connecting portion 6a and the second connecting portion 6b, extending in the first direction (X axis plus direction It has a base 7 that extends to the ). With this configuration, the sensor element 50 is configured as an acceleration sensor with a so-called one-sided seesaw structure, in which the movable body 8 swings around the pivot axis 61.

[0015] Furthermore, the first connecting portion 6a and the second connecting portion 6b are arranged symmetrically with respect to the center line 60 as the axis of symmetry. The center line 60 is a virtual line, a line segment that passes through the center of the fixing portion 3 and lies along the Y axis. The base portion 7 is also arranged symmetrically with respect to the center line 60 as the axis of symmetry.

[0016] A movable electrode section 20 is provided on the base 7. The movable electrode section 20 consists of a first movable electrode group 20a, a second movable electrode group 20b, a third movable electrode group 20c, and a fourth movable electrode group 20d. The movable electrode group 20a consists of four movable electrodes 21 extending from the base 7 in the Y-minus direction. The four movable electrodes 21 are arranged in a comb-like pattern at equal pitches along the extending direction of the base 7. Similarly, the movable electrode group 20b consists of four movable electrodes 22 extending from the base 7 in the Y-minus direction. The four movable electrodes 22 are arranged in a comb-like manner at equal pitches along the extending direction of the base 7. Note that the number of movable electrodes 21 and 22 is not limited to four; there may be multiple electrodes, for example, eight or even ten.

[0017] The movable electrode group 20c is a pair of electrodes with the movable electrode group 20b, and consists of four movable electrodes 22 extending from the base 7 in the Y-minus direction. The movable electrode group 20c is provided symmetrically with respect to the movable electrode group 20b with respect to the center line 60 as the axis of symmetry. The movable electrode group 20d is a pair of electrodes with the movable electrode group 20a, and consists of four movable electrodes 21 extending from the base 7 in the Y-minus direction. The movable electrode group 20d is positioned symmetrically with respect to the movable electrode group 20a with respect to the center line 60 as the axis of symmetry.

[0018] The base body 1 is provided with a fixed electrode section 10 facing the movable electrode section 20. The fixed electrode section 10 consists of a first fixed electrode group 10a, a second fixed electrode group 10b, a third fixed electrode group 10c, and a fourth fixed electrode group 10d. The fixed electrode group 10a consists of a base portion 9a provided on the base body 1 and three fixed electrodes 11 extending from the base portion 9a in the Y-plus direction. The three fixed electrodes 11 are arranged in a comb-like pattern at equal pitch so as to fit into the gaps between the four movable electrodes 21 in the movable electrode group 20a. As a result, the fixed electrodes 11 and the movable electrodes 21 are positioned to face each other in the X direction.

[0019] The fixed electrode group 10b consists of a base portion 9b provided on the base body 1 and three fixed electrodes 12 extending from the base portion 9b in the Y-positive direction. The three fixed electrodes 12 are arranged in a comb-like pattern at equal pitch so as to fit into the gaps between the four movable electrodes 22 in the movable electrode group 20b. As a result, the fixed electrodes 12 and the movable electrodes 22 are arranged to face each other in the X direction. The fixed electrode group 10c is a pair of electrodes with the fixed electrode group 10b, and consists of a base portion 9c provided on the base body 1 and three fixed electrodes 12 extending from the base portion 9c in the Y-plus direction. The three fixed electrodes 12 are arranged in a comb-like pattern at equal pitch so as to fit into the gaps between the four movable electrodes 22 in the movable electrode group 20c. As a result, the fixed electrodes 12 and the movable electrodes 22 are arranged to face each other in the X direction. The fixed electrode group 10c may also be arranged symmetrically with respect to the fixed electrode group 10b with respect to the center line 60 as the axis of symmetry.

[0020] The fixed electrode group 10d is a pair of electrodes with the fixed electrode group 10a, and consists of a base portion 9d provided on the base body 1 and three fixed electrodes 11 extending from the base portion 9d in the Y-plus direction. The three fixed electrodes 11 are arranged in a comb-like pattern at equal pitch so as to fit into the gaps between the four movable electrodes 21 in the movable electrode group 20d. The fixed electrode group 10d may be arranged symmetrically with respect to the fixed electrode group 10a with respect to the center line 60 as the axis of symmetry. As a result, the fixed electrodes 11 and the movable electrodes 21 are arranged to face each other in the X direction. Note that the number of fixed electrodes 11 and 12 is not limited to three, but can be any number corresponding to the number of movable electrodes 21 and 22. For example, if there are eight movable electrodes 21, there may be seven fixed electrodes 11.

[0021] In other words, the fixed electrode section 10 has fixed electrode groups 10a, 10b, 10c, and 10d provided on the base 1. The movable electrode section 20 includes a movable electrode group 20a having a movable electrode 21 facing the fixed electrode 11 of the fixed electrode group 10a, a movable electrode group 20b having a movable electrode 22 facing the fixed electrode 12 of the fixed electrode group 10b, a movable electrode group 20c having a movable electrode 22 facing the fixed electrode 12 of the fixed electrode group 10c, and a movable electrode group 20d having a movable electrode 21 facing the fixed electrode 11 of the fixed electrode group 10d. Then, in the first direction (X-plus direction) of the base 7, the movable electrode groups 20a, 20b, 20c, and 20d are arranged in this order.

[0022] ***Configuration of fixed electrode, movable electrode, and detection unit*** Figure 3 is a perspective view showing the three-dimensional shape of the electrode group, specifically a perspective view of the fixed electrode group 10a and the movable electrode group 20a. As shown in Figure 3, the movable electrode 21 has a recessed thickness in the Y direction. Specifically, the movable electrode 21 is thinner in the Y direction in the area indicated by range a. In other words, the movable electrode 21 is thinned by being cut in a step-like manner from the same thickness as the base 7 at the root to the Y-minus direction. As a result, all four movable electrodes 21 have a thinner thickness on the Z-plus side in the portion facing the fixed electrode 11 of the fixed electrode group 10a. Here, the detection unit consisting of the fixed electrode group 10a and the movable electrode group 20a is referred to as the N-type detection unit 25n. In the N-type detection unit 25n, a parallel plate type capacitance is formed by the opposing fixed electrode 11 and movable electrode 21. This capacitance changes in accordance with the change in the overlapping area between the fixed electrode 11 and the movable electrode 21 as the movable electrode 21 is displaced due to acceleration. Similarly, the detection unit consisting of a fixed electrode group 10d (Figure 1) and a movable electrode group 20d is called the N-type detection unit 26n. The N-type detection unit 26n is an N-type detection unit that is paired with the N-type detection unit 25n, and is provided symmetrically with respect to the N-type detection unit 25n with respect to the center line 60 as the axis of symmetry.

[0023] Figure 4 is a perspective view showing the three-dimensional shape of the electrode group, specifically a perspective view of the fixed electrode group 10b and the movable electrode group 20b. As shown in Figure 4, the fixed electrode 12 has a recessed thickness in the Y-axis direction. Specifically, the fixed electrode 12 is thinner in the Y-direction in the area indicated by range b. In other words, the fixed electrode 12 is thinned by being cut in a step-like manner from the same thickness as the base portion 9b at the base to the middle of the positive Y-axis direction. As a result, all three fixed electrodes 12 have a thinner thickness on the positive Z-axis side in the portion facing the movable electrode 22 of the movable electrode group 20b. Here, the detection unit consisting of the fixed electrode group 10b and the movable electrode group 20b is referred to as the P-type detection unit 25p. In the P-type detection unit 25p, a parallel plate type capacitance is formed by the fixed electrode 12 and the movable electrode 22 which are arranged opposite each other. This capacitance changes in accordance with the change in the overlap area between the movable electrode 22 and the fixed electrode 12 as the movable electrode 22 is displaced due to acceleration. Similarly, the detection unit consisting of the fixed electrode group 10c (Figure 1) and the movable electrode group 20c is called the P-type detection unit 26p. The P-type detection unit 26p is paired with the P-type detection unit 25p. P This is a type detection unit, and it is positioned symmetrically with respect to the P-type detection unit 25p, with the center line 60 as the axis of symmetry.

[0024] In other words, the thickness of each movable electrode 22 in movable electrode group 20b and each movable electrode 22 in movable electrode group 20c is different from the thickness of each movable electrode 21 in movable electrode group 20a and each movable electrode 21 in movable electrode group 20d. Furthermore, with the center line 60, which is an imaginary line extending in the Y-plus direction from the center of the fixed part 3, as the axis of symmetry, each movable electrode 21 in movable electrode group 20a is arranged symmetrically with respect to each movable electrode 21 in movable electrode group 20d, and each movable electrode 22 in movable electrode group 20b is arranged symmetrically with respect to each movable electrode 22 in movable electrode group 20c.

[0025] ***Principle of Acceleration Detection*** Figure 5 is an explanatory diagram of the acceleration detection principle. Figure 5 shows the initial state on the left and the state with acceleration on the right, showing the case where the direction of acceleration is in the Z-positive direction and the Z-negative direction. Specifically, it shows the degree of overlap between the fixed electrode 11 and the movable electrode 21, and the degree of overlap between the fixed electrode 12 and the movable electrode 22 in a cross-section along the XZ plane. The initial state is the state in which no acceleration occurs, including gravity, in the Z-positive and Z-negative directions. Hereafter, the Z-positive and Z-negative directions will also be referred to as the Z-positive / Z-negative directions.

[0026] First, in the initial state, in the N-type detection unit 25n, the positions of the ends of the fixed electrode 11 and the movable electrode 21 on the Z-minus side coincide and are flush. Similarly, in the P-type detection unit 25p, the positions of the ends of the fixed electrode 12 and the movable electrode 22 on the Z-minus side coincide and are flush. The overlapping area of ​​the fixed electrode 11 and the movable electrode 21, and the overlapping area of ​​the fixed electrode 12 and the movable electrode 22 in the initial state are also called the initial area.

[0027] Next, when acceleration occurs in the Z-positive direction, the movable electrode 21 of the N-type detection unit 25n and the movable electrode 22 of the P-type detection unit 25p are each displaced to the Z-negative side due to the inertial force associated with the acceleration. At this time, the overlapping area between the fixed electrode 11 and the movable electrode 21 in the N-type detection unit 25n becomes smaller than the initial area due to the displacement of the movable electrode 21 in the Z-negative direction. On the other hand, in the P-type detection unit 25p, the overlapping area between the fixed electrode 12 and the movable electrode 22 is maintained at the initial area even when the movable electrode 22 is displaced in the Z-negative direction. In other words, the overlapping area does not change even when the movable electrode 22 is displaced in the Z-negative direction. Thus, when acceleration occurs in the Z-positive direction, the overlapping area decreases in the N-type detection unit 25n, while the overlapping area is maintained in the P-type detection unit 25p.

[0028] Next, when acceleration occurs in the Z-negative direction, the movable electrode 21 of the N-type detection unit 25n and the movable electrode 22 of the P-type detection unit 25p are each displaced to the Z-positive side due to the inertial force associated with the acceleration. At this time, the overlapping area between the fixed electrode 11 and the movable electrode 21 in the N-type detection unit 25n is maintained at its initial area even when the movable electrode 21 is displaced in the Z-positive direction. On the other hand, the overlapping area between the fixed electrode 12 and the movable electrode 22 in the P-type detection unit 25p becomes smaller than the initial area due to the displacement of the movable electrode 22 in the Z-positive direction. Thus, when acceleration occurs in the Z-negative direction, the overlap area is maintained in the N-type detection unit 25n, while the overlap area decreases in the P-type detection unit 25p.

[0029] Furthermore, the behavior of the N-type detection unit 26n, which is paired with the N-type detection unit 25n, when acceleration in the Z direction is applied is the same as that of the N-type detection unit 25n. Similarly, the behavior of the P-type detection unit 26p, which is paired with the P-type detection unit 25p, when acceleration in the Z direction is applied is the same as that of the P-type detection unit 25p. Based on the correlation described above, acceleration in the Z-positive / -negative direction can be detected by detecting the change in the overlapping area of ​​the N-type detection units 25n, 26n and the P-type detection units 25p, 26p as a change in capacitance. More specifically, acceleration in the Z-positive / -negative direction can be detected by detecting the difference between the capacitance of the N-type detection units 25n, 26n and the capacitance of the P-type detection units 25p, 26p using a differential amplifier circuit. The differential amplifier circuit is built into the control IC 236 (Figure 13), which will be described later. An AC detection signal is used when detecting acceleration. Furthermore, although the above description assumes that notches are provided in the movable electrode 21 and the fixed electrode 12, the configuration is not limited to this, and for example, notches may be provided in the fixed electrode 11 and the movable electrode 22.

[0030] Return to Figure 1. The X-plus side of the base body 1 is provided with an overhang 1c that extends from the cover body 5, and multiple connecting pads are provided on the overhang 1c. The connecting pad 41 is electrically connected to the fixed electrode group 10a of the N-type detection unit 25n and the fixed electrode group 10d of the N-type detection unit 26n by wiring 71. The connecting pad 42 is electrically connected to the fixed electrode group 10b of the P-type detection unit 25p and the fixed electrode group 10c of the P-type detection unit 26p by wiring 72. The connecting pad 44 is electrically connected to the movable electrode unit 20 via the movable body 8 by wiring 74. The connection pads 41, 42, and 44 are electrically connected to the control IC 236 (Figure 13) via wiring such as bonding wires (not shown).

[0031] ***Damper section configuration*** Furthermore, the sensor element 50 is provided with a pair of damper portions 65a and 65b. The damper section 65a is provided on the side of the first connecting section 6a of the movable body 8, and consists of a damper movable section 30a and a damper fixed section 45a. The damper movable section 30a consists of a first bar 31a that branches off from the first connecting section 6a in the X-minus direction, and two second bars 32. The two second bars 32 extend in the Y direction and intersect the first bar 31a in a cross shape. The two second bars 32 are arranged with a gap between them, and the third bar 46 of the damper fixing portion 45a is positioned between this gap. The first bar 31a and the second bars 32 are formed to the same thickness as the first connecting portion 6a.

[0032] The damper fixing portion 45a is provided on the base body 1 and consists of three third bars 46 arranged at equal intervals and connecting portions 47 that connect the three third bars 46 at the top and bottom, respectively. As shown in Figure 1, the two second bars 32 of the damper movable part 30a and the three third bars 46 of the damper fixed part 45a are arranged in a comb-like manner with gaps between them. Of the three third bars 46, the two third bars 46 on the first connecting part 6a side are separated at the point where they intersect with the first bar 31a. Furthermore, since both ends of the damper fixing portion 45a in the Y direction are connected by the connecting portion 47, the outer shape of the damper fixing portion 45a is rectangular in plan view, and the damper fixing portion 45a surrounds the damper movable portion 30a. The thickness of the third bar 46 and the connecting portion 47 is the same as that of the first bar 31a and the second bar 32.

[0033] The damper portion 65b is provided on the second connecting portion 6b side of the movable body 8, and is provided symmetrically with respect to the damper portion 65a with respect to the center line 60 as the axis of symmetry. The damper section 65b consists of a damper movable section 30b and a damper fixed section 45b. The damper movable section 30b consists of a first bar 31b that branches off from the second connecting section 6b in the positive direction of the X axis, and two second bars 32. The two second bars 32 extend in the Y direction and intersect the first bar 31b in a cross shape. The two second bars 32 are arranged with a gap between them, and the third bar 46 of the damper fixed section 45b is positioned between this gap. b The second bar 32 is formed to have the same thickness as the second connecting portion 6b.

[0034] The damper fixing section 45b is provided on the base body 1 and consists of three third bars 46 arranged at equal intervals and connecting sections 47 that connect the three third bars 46 at the top and bottom, respectively. The two second bars 32 of the damper movable section 30b and the three third bars 46 of the damper fixed section 45b are arranged in a comb-like manner with gaps between them. Of the three third bars 46, the two third bars 46 on the second connecting section 6b side are separated at the point where they intersect with the first bar 31b. Furthermore, since both ends of the damper fixing portion 45b in the Y direction are connected by the connecting portion 47, the outer shape of the damper fixing portion 45b is rectangular in plan view, and the damper fixing portion 45b surrounds the damper movable portion 30b. The thickness of the third bar 46 and the connecting portion 47 is the same as that of the first bar 31b and the second bar 32.

[0035] Thus, the damper sections 65a and 65b, which are provided symmetrically on the left and right sides of the movable body 8 with respect to the center line 60 as the axis of symmetry, play a role in damping unwanted vibrations of the movable body 8. Specifically, for example, when the movable body 8 is displaced by an acceleration in the X direction, the damper movable section 30a of the damper section 65a also displaces together with the movable body 8. At this time, the air resistance in the space between the damper fixed section 45a and the damper movable section 30a suppresses the displacement in the X direction. The same applies to the damper section 65b. Furthermore, when the movable body 8 is subjected to a greater acceleration, the damper movable section 30a strikes the damper fixed section 45a, thereby functioning as a stopper. As described above, when acceleration occurs in a direction other than the Z direction in the movable body 8, the damper sections 65a and 65b play a role in damping unwanted displacement and vibration of the movable body 8 in directions other than the Z direction, thereby suppressing the multi-axis sensitivity of the acceleration sensor 100.

[0036] ***Effects of symmetrical construction*** Figure 6 is a plan view of the comparative physical quantity sensor and corresponds to Figure 1. The acceleration sensor 90 used as a physical quantity sensor in the comparative example shown in Figure 6 is an example of a conventional physical quantity sensor. Note that the same numbers are used for parts identical to those described in Figure 1, and redundant explanations are omitted.

[0037] The comparative example acceleration sensor 90 differs from the acceleration sensor 100 of Embodiment 1 in that the base 7 of the movable body 89 is provided with two detection units, an N-type detection unit 25n and a P-type detection unit 25p, and the acceleration sensor 90 is not provided with damper units 65a and 65b. Other than these differences, the description is the same as in Figure 1. In the acceleration sensor 90, the movable electrode section 29 consists of two movable electrode groups: a 20a and a 20b. The fixed electrode section 19 consists of two fixed electrode groups: a 10a and a 10b. The fixed electrode group 10a and the movable electrode group 20a form an N-type detection section 25n, and the fixed electrode group 10b and the movable electrode group 20b form a P-type detection section 25p.

[0038] Here, the N-type detection unit 25n and the P-type detection unit 25p are arranged symmetrically in a planar manner with respect to the center line 60 as the axis of symmetry, but the weight balance of the movable body 89 was disrupted. Specifically, the movable electrode 21 of the movable electrode group 20a is thinner than the movable electrode 22 of the movable electrode group 20b, and therefore the X of the movable body 89 was disrupted. axis The mass in the negative direction became lighter, disrupting the weight balance between the left and right sides. As a result, in the comparative example acceleration sensor 90, when acceleration was applied, twisting and distortion occurred in the oscillation of the movable body 89, leading to problems such as increased sensitivity in other axes and a decrease in detection accuracy.

[0039] In contrast, the acceleration sensor 100 of this embodiment is configured such that pairs of N-type detection units 25n and P-type detection units 25p, and pairs of N-type detection units 26n and P-type detection units 26p are arranged symmetrically with respect to the center line 60, thereby achieving weight balance on both sides. Specifically, the weight on both sides of the base 7 is made equal by matching the number of movable electrodes 21 and 22 on the left side (X-minus direction) with respect to the center line 60, and the number of movable electrodes 21 and 22 on the right side (X-plus direction). It should be noted that the configuration is not limited to one pair on each side, but is acceptable as long as the same number of pairs are provided on both sides. That is, there may be six detection units or eight detection units. The number of detection units is preferably a multiple of four. Furthermore, the arrangement may be symmetrical on both sides, for example, a P-type-N-type-N-type-P-type arrangement is also acceptable. Furthermore, since damper sections 65a and 65b are provided symmetrically on both sides, unwanted vibrations of the movable body 8 can be damped, and interaxial sensitivity can be suppressed.

[0040] As described above, the acceleration sensor 100 as a physical quantity sensor in this embodiment provides the following benefits. An acceleration sensor 100 for detecting a physical quantity in the Z direction, which is the third direction, when mutually orthogonal directions are defined as the first direction, second direction, and third direction, comprising: a fixed part 3 fixed to a base body 1; a first rotating spring 4a and a second rotating spring 4b as support beams with one end connected to the fixed part 3; a fixed electrode part 10 provided on the base body 1 and having a first fixed electrode group 10a, a second fixed electrode group 10b, a third fixed electrode group 10c, and a fourth fixed electrode group 10d; a first movable electrode group 20a having a movable electrode 21 facing the fixed electrode 11 of the fixed electrode group 10a; and a movable electrode 22 facing the fixed electrode 12 of the fixed electrode group 10b. The movable electrode section 20 includes a movable electrode group 20b as a second movable electrode group, a movable electrode group 20c as a third movable electrode group having a movable electrode 22 facing the fixed electrode 12 of the fixed electrode group 10c, and a movable electrode group 20d as a fourth movable electrode group having a movable electrode 21 facing the fixed electrode 11 of the fixed electrode group 10d, and a movable body 8 having the movable electrode section 20, wherein in the first direction, the movable electrode group 20a, movable electrode group 20b, movable electrode group 20c, and movable electrode group 20d are arranged in this order, and the thickness of each movable electrode 22 of the movable electrode group 20b and each movable electrode 22 of the movable electrode group 20c is different from the thickness of each movable electrode 21 of the movable electrode group 20a and each movable electrode 21 of the movable electrode group 20d, and from the center of the fixed part 3 Y axis plus direction Extends attitude With the imaginary center line 60 as the axis of symmetry, each movable electrode 21 of the movable electrode group 20a is arranged symmetrically with each movable electrode 21 of the movable electrode group 20d, and each movable electrode 22 of the movable electrode group 20b is arranged symmetrically with each movable electrode 22 of the movable electrode group 20c.

[0041] According to this, with the center line 60 as the axis of symmetry, the number of movable electrodes 21 and 22 on the left side (X-minus direction) and the number of movable electrodes 21 and 22 on the right side (X-plus direction) are the same, making it possible to equalize the weight balance on the left and right sides of the movable body 8. Furthermore, since an N-type detection unit 25n and a P-type detection unit 25p are arranged on the left side, and an N-type detection unit 26n and a P-type detection unit 26p are arranged on the right side, acceleration can be detected distinguishing between the Z-plus and Z-minus directions by two N-type and two P-type detection units. Therefore, the acceleration sensor 100 has good weight balance with the movable body 8 and high detection accuracy. Therefore, it is possible to provide an acceleration sensor 100 in which multi-axis sensitivity is suppressed and detection accuracy is high.

[0042] Furthermore, the support beam has a first rotary spring 4a with one end fixed to the fixing part 3 and extending in a first direction, and a second rotary spring 4b with one end fixed to the fixing part 3 and extending in a direction opposite to the first direction. The movable body 8 has a first connecting part 6a with one end connected to the other end of the first rotary spring 4a and extending in a second direction, a second connecting part 6b with one end connected to the other end of the second rotary spring 4b and extending in a second direction, and a base part 7 that connects the first connecting part 6a and the second connecting part 6b and extends in a first direction. The movable electrode groups 20a, 20b, 20c, and 20d are connected to the base part 7. According to this, if the first rotating spring 4a and the second rotating spring 4b, which are integrated with the fixed part 3, are considered as one side of the fixed axis, a structurally stable rectangle is formed between the fixed axis and the movable body 8. Therefore, when the movable body 8 swings around the fixed axis, it can swing stably. In other words, acceleration can be detected stably.

[0043] Furthermore, the movable body 8 is equipped with damper sections 65a and 65b that are arranged symmetrically on the left and right sides. Therefore, when acceleration occurs in a direction other than the Z direction in the movable body 8, unwanted displacements and vibrations of the movable body 8 in directions other than the Z direction can be damped, and the sensitivity to other axes can be reduced. Therefore, it is possible to provide an acceleration sensor 100 with suppressed sensitivity in other axes and higher detection accuracy.

[0044] Embodiment 2 ***Different Embodiments of Sensor Elements - 1*** Figure 7 is a plan view of the sensor element according to Embodiment 2, and corresponds to Figure 1. In the above embodiment, it was described that a plurality of movable electrodes 21, 22 protrude from the base 7 in a comb-like manner in intersecting directions, and a plurality of fixed electrodes 11, 12 are provided opposite the movable electrodes. However, the configuration is not limited to this, and any configuration in which a parallel plate type capacitance can be formed between the two electrodes is acceptable. For example, the acceleration sensor 110 of this embodiment employs a configuration having movable electrodes 21c and 22c that extend in the same direction as the extension direction of the base portion 7. Hereafter, the same parts as in the above embodiment will be numbered, and redundant explanations will be omitted.

[0045] The acceleration sensor 110 of this embodiment, shown in Figure 7, is equipped with an N-type detection unit 75n, a P-type detection unit 75p, a P-type detection unit 76p, and an N-type detection unit 76n in that order from the second connecting portion 6b side at the base portion 7. In other words, the pair of N-type detection unit 75n and P-type detection unit 75p and the pair of N-type detection unit 76n and P-type detection unit 76p are arranged symmetrically with respect to the center line 60 as the axis of symmetry. The N-type detection unit 75n is composed of a movable electrode group 70a and a fixed electrode group 80a. The movable electrode group 70a consists of an electrode axis 33a that branches from the base 7 in the Y-minus direction and two movable electrodes 21c. The two movable electrodes 21c branch off to the left and right from the middle of the electrode axis 33a and extend in the X direction. The two movable electrodes 21c are arranged with a gap between them, and the fixed electrode 11c of the fixed electrode group 80a is positioned between this gap.

[0046] The fixed electrode group 80a is provided on the base 1 and consists of three fixed electrodes 11c arranged at equal intervals and connecting parts 34 that connect the three fixed electrodes 11c on the left and right sides, respectively. The two movable electrodes 21c of the movable electrode group 70a and the three fixed electrodes 11c of the fixed electrode group 80a are arranged in a comb-like manner with gaps between them. Of the three fixed electrodes 11c, the two fixed electrodes 11c on the base 7 side are separated at the point where they intersect with the electrode axis 33a. Furthermore, since both ends of the fixed electrode group 80a in the X direction are connected by the connecting portion 34, the outer shape of the fixed electrode group 80a is rectangular in plan view, and the fixed electrode group 80a surrounds the movable electrode group 70a. Even with this configuration, a parallel plate type capacitance is formed between the movable electrode 21c and the fixed electrode 11c, making it possible to detect capacitance changes accompanying the oscillation of the movable body 8b.

[0047] The P-type detection unit 75p consists of a movable electrode group 70b and a fixed electrode group 80b. The movable electrode group 70b consists of an electrode axis 33b that branches from the base 7 in the Y-minus direction and two movable electrodes 22c. The two movable electrodes 22c branch off to the left and right from the middle of the electrode axis 33b and extend in the X direction. The two movable electrodes 22c are arranged with a gap between them, and the fixed electrode 12c of the fixed electrode group 80b is positioned between this gap.

[0048] The fixed electrode group 80b is provided on the base 1 and consists of three fixed electrodes 12c arranged at equal intervals and connecting parts 35 that connect the three fixed electrodes 12c on the left and right sides, respectively. The two movable electrodes 22c of the movable electrode group 70b and the three fixed electrodes 12c of the fixed electrode group 80b are arranged in a comb-like manner with gaps between them. Of the three fixed electrodes 12c, the two fixed electrodes 12c on the base 7 side are separated at the point where they intersect with the electrode axis 33b. Furthermore, since both ends of the fixed electrode group 80b in the X direction are connected by the connecting portion 35, the outer shape of the fixed electrode group 80b is rectangular in plan view, and the fixed electrode group 80b surrounds the movable electrode group 70b. Even with this configuration, a parallel plate type capacitance is formed between the movable electrode 22c and the fixed electrode 12c, making it possible to detect capacitance changes accompanying the oscillation of the movable body 8b.

[0049] The P-type detection unit 76p is configured symmetrically with respect to the P-type detection unit 75p, with respect to the center line 60 as the axis of symmetry. The N-type detection unit 76n is configured symmetrically with respect to respect to the N-type detection unit 75n, with respect to the center line 60 as the axis of symmetry. In other words, pairs of N-type detection unit 75n and P-type detection unit 75p, and pairs of N-type detection unit 76n and P-type detection unit 76p are provided symmetrically with respect to respect to the center line 60 as the axis of symmetry.

[0050] Here, the thickness of the movable electrode 21c of the movable electrode group 70a in the N-type detection unit 75n in the Z direction is set to be the same as the thickness of the movable electrode 21 of the movable electrode group 20a in Embodiment 1 shown in Figure 3. Specifically, the thickness of the electrode shaft 33a is cut in a step-like manner from the same thickness as the base portion 7 at the root, and becomes thinner in the Y-minus direction, until it is the same as the thickness of the movable electrode 21. The two movable electrodes 21c that branch off from the electrode shaft 33a are also made to be the same thickness as the movable electrode 21. On the other hand, the thickness of the fixed electrode 11c of the fixed electrode group 80a in the Z direction is set to be the same as the thickness of the fixed electrode 11 of the fixed electrode group 10a in Embodiment 1 shown in Figure 3. The same applies to the N-type detection unit 76n.

[0051] Furthermore, the thickness of the movable electrode 22c in the movable electrode group 70b in the P-type detection unit 75p in the Z direction is set to be the same as the thickness of the movable electrode 22 in the movable electrode group 20b of Embodiment 1 shown in Figure 4. Specifically, the thickness of the movable electrode 22c is the same as the thickness of the base 7. On the other hand, the thickness of the fixed electrode 12c of the fixed electrode group 80b in the Z direction is set to be the same as the thickness of the fixed electrode 12 of the fixed electrode group 10b of Embodiment 1 shown in Figure 4. More specifically, the overall thickness (height) of the fixed electrode group 80b, which includes the three fixed electrodes 12c, is thinner (lower) than that of the fixed electrode group 80a and is set to be the same as the thickness of the fixed electrode 12. The same applies to the P-type detection unit 76p.

[0052] As a result, the overlap in the Z direction of the N-type detection units 75n, 76n and the P-type detection units 75p, 76p in their initial state will be the same as in Figure 5. Furthermore, the behavior when acceleration is applied will also be the same as in Figure 5. Therefore, by detecting the change in the overlapping area of ​​the N-type detection units 75n, 76n and the P-type detection units 75p, 76p as a change in capacitance, acceleration in the Z-positive / Z-negative direction can be detected.

[0053] As described above, the acceleration sensor 110 as a physical quantity sensor in this embodiment provides the following effects in addition to those of the above embodiment. Even if the base portion 7 has an acceleration sensor 110 configured with an N-type detection unit 75n, a P-type detection unit 75p, a P-type detection unit 76p, and an N-type detection unit 76n in that order from the second connecting portion 6b side, acceleration can be detected in the same way as with the acceleration sensor 100. Therefore, the accelerometer 110 has good weight balance with the movable body 8b and high detection accuracy. Therefore, it is possible to provide an acceleration sensor 110 in which multi-axis sensitivity is suppressed and detection accuracy is high.

[0054] Embodiment 3 ***Different forms of sensor elements - 2*** Figure 8 is a plan view of the sensor element according to Embodiment 3, and corresponds to Figure 1. In the above embodiment, the movable body 8 was described as having a frame-like structure in which the base 7 is supported by two pillars, the first connecting portion 6a and the second connecting portion 6b. However, the configuration is not limited to this, and any configuration that can support the base in a swingable manner is acceptable. For example, the acceleration sensor 120 of this embodiment employs a configuration in which the base 77 is supported by a single support arm 66. Hereafter, the same parts as in the above embodiment will be numbered, and redundant explanations will be omitted.

[0055] As shown in Figure 8, in the acceleration sensor 120 of this embodiment, the sensor element 52 is supported by two fixing parts: a first fixing part 43a and a second fixing part 43b. In other words, the fixing part has a first fixing part 43a and a second fixing part 43b spaced apart from the first fixing part 43a in the opposite direction to the first direction. Here, the center line 60 is a line segment that passes through the centers of the first fixing part 43a and the second fixing part 43b and lies along the Y axis. Note that although there are two fixing parts here, if there are three or more fixing parts, the center line 60 is a line segment that passes through the center of the three or more fixing parts combined and lies along the Y axis. The support beam includes a first rotating spring 64a as a first support beam, with one end fixed to the first fixing part 43a and extending in the X-minus direction opposite to the first direction, and a second rotating spring 64b as a second support beam, with one end fixed to the second fixing part 43b and extending in the X-plus direction.

[0056] The support arm 66 is a connecting part, provided on the center line 60 and extending in the Y direction. One end of the support arm 66 is connected to the other end of the first rotary spring 64a and the other end of the second rotary spring 64b. The other end of the support arm 66 is connected to the center of the base 77. The base 77 is a plate-shaped member extending in the X direction. Furthermore, the part of the base 77 on the positive side of the X axis is also called the first base 77a, and the part on the negative side of the X axis is also called the second base 77b, with respect to the center line 60. In other words, the movable body 85 has a support arm 66 as a connecting part that extends in the positive direction of the Y axis, with one end connected to the other end of the first fixed part 43a and the other end of the second fixed part 43b, and the other end of the support arm 66 is connected to the X axis plus direction It has a first base portion 77a extending in the direction of the first direction, and a second base portion 77b connected to the other end of the support arm 66 and extending in the negative direction of the X-axis opposite to the first direction.

[0057] The acceleration sensor 120 is equipped with, in the base portion 77, an N-type detection unit 25n, a P-type detection unit 25p, a P-type detection unit 26p, and an N-type detection unit 26n in that order from the X-minus side. In other words, the pair of N-type detection unit 25n and P-type detection unit 25p and the pair of N-type detection unit 26n and P-type detection unit 26p are arranged symmetrically with respect to the center line 60 as the axis of symmetry. In other words, the movable electrode group 20a of the N-type detection unit 25n and the movable electrode group 20b of the P-type detection unit 25p are connected to the second base 77b, while the movable electrode group 20c of the P-type detection unit 26p and the movable electrode group 20d of the N-type detection unit 26n are connected to the first base 77a.

[0058] As described above, the acceleration sensor 120 as a physical quantity sensor in this embodiment provides the following effects in addition to the effects of the above embodiment. According to the acceleration sensor 120, the fixed part has a first fixed part 43a and a second fixed part 43b spaced apart from the first fixed part 43a in the opposite direction to the first direction, the support beam has a first rotating spring 64a as a first support beam with one end fixed to the first fixed part 43a and extending in the negative direction of the X axis opposite to the first direction, and a second rotating spring 64b as a second support beam with one end fixed to the second fixed part 43b and extending in the positive direction of the X axis, the movable body 85 has a support arm 66 as a connecting part with one end connected to the other end of the first fixed part 43a and the other end of the second fixed part 43b and extending in the positive direction of the Y axis, and the other end of the support arm 66 is connected to the X axis plus direction It has a first base portion 77a extending in the direction of the first direction and a second base portion 77b connected to the other end of the support arm 66 and extending in the negative direction of the X-axis opposite to the first direction. The movable electrode group 20a of the N-type detection unit 25n and the movable electrode group 20b of the P-type detection unit 25p are connected to the second base portion 77b, and the movable electrode group 20c of the P-type detection unit 26p and the movable electrode group 20d of the N-type detection unit 26n are connected to the first base portion 77a.

[0059] According to this, with the center line 60 as the axis of symmetry, the number of movable electrodes 21 and 22 on the left side is the same as the number of movable electrodes 21 and 22 on the right side, and the movable body 8 5This allows for a uniform weight balance between the left and right sides. Furthermore, even if the base 77 is supported by a single support arm 66, a stable structure can be achieved by supporting the support arm 66 with two first fixing parts 43a and second fixing parts 43b. Therefore, the accelerometer 120 has high detection accuracy because the weight balance of the movable body 85 is good. Therefore, it is possible to provide an acceleration sensor 120 with reduced sensitivity in other axes and high detection accuracy. can.

[0060] Embodiment 4 ***Different forms of sensor elements - 3*** Figure 9 is a plan view of the sensor element according to Embodiment 4, and corresponds to Figure 1. In the above embodiment, the movable electrodes 21 and 22 were described as being provided on one side (Y-negative side) of the base 7 of the movable body 8. However, the configuration is not limited to this, and the movable electrodes 21 and 22 may be provided on both sides of the base. For example, the acceleration sensor 130 of this embodiment includes a first base portion 68a that branches off from the first connecting portion 6a, and employs a configuration in which movable electrodes 21 and 22 are provided on both sides of the first base portion 68a. The second connecting portion 6b also includes a second base portion 68b that is symmetrical to the first base portion 68a. Hereafter, the same parts as in the above embodiment will be numbered, and redundant explanations will be omitted.

[0061] As shown in Figure 9, the sensor element 53 of the acceleration sensor 130 in this embodiment includes a first base portion 68a that branches off from the first connecting portion 6a in the negative direction of the X axis, and a second base portion 68b that branches off from the second connecting portion 6b in the positive direction of the X axis. The first base portion 68a and the second base portion 68b are not connected and are separated by the center line 60. In other words, the movable body 8c has a first base portion 68a that extends from the first connecting portion 6a in the negative direction of the X axis opposite to the first direction, and a second base portion 68b that extends from the second connecting portion 6b in the X axis plus direction Extends attitude It has a second base portion 68b. The other end of the first base 68a and the other end of the second connecting part 6b are connected by a connecting beam 17. The connecting beam 17 is the beam corresponding to the base 7 in Figure 1 and forms the outer edge of the rectangular movable body 8c. To accomplish.

[0062] On the Y-minus side of the second base 68b, an N-type detection unit 25n and a P-type detection unit 25p are provided in that order, starting from the second connecting unit 6b side. Similarly, on the Y-plus side, an N-type detection unit 25n and a P-type detection unit 25p are provided in that order, starting from the second connecting unit 6b side. In other words, the second base 68b has four detection units on both sides in the Y direction, consisting of two N-type detection units 25n and two P-type detection units 25p. On the Y-minus side of the first base 68a, a P-type detection unit 26p and an N-type detection unit 26n are provided in that order, starting from the center line 60 side. Similarly, on the Y-plus side, a P-type detection unit 26p and an N-type detection unit 26n are provided in that order, starting from the center line 60 side. In other words, the first base 68a has four detection units on both sides in the Y direction, consisting of two P-type detection units 26p and two N-type detection units 26n.

[0063] Thus, the first base 68a, which includes four detection units, and the second base 68b, which also includes four detection units, are arranged symmetrically with respect to the center line 60 as the axis of symmetry. It should be noted that the arrangement is not limited to providing detection units on both sides of the first base 68a and the second base 68b; a symmetrical configuration is sufficient, and detection units may be provided on only one side. In other words, the movable electrode group 20a of the N-type detection unit 25n and the movable electrode group 20b of the P-type detection unit 25p are connected to the second base 68b, while the movable electrode group 20c of the P-type detection unit 26p and the movable electrode group 20d of the N-type detection unit 26n are connected to the first base 68a.

[0064] As described above, the acceleration sensor 130 as a physical quantity sensor in this embodiment provides the following effects in addition to those of the above embodiment. According to the acceleration sensor 130, the support beam has a first rotary spring 4a with one end fixed to the fixing part 3 and extending in a first direction, and a second rotary spring 4b with one end fixed to the fixing part 3 and extending in the direction opposite to the first direction, and the movable body 8c has a first connecting part 6a with one end connected to the other end of the first rotary spring 4a and extending in a second direction, a second connecting part 6b with one end connected to the other end of the second rotary spring 4b and extending in a second direction, a first base part 68a extending from the first connecting part 6a in the negative direction of the X axis opposite to the first direction, and from the second connecting part 6b in the X axis plus direction It has a second base portion 68b extending from it, and the movable electrode group 20a of the N-type detection unit 25n and the movable electrode group 20b of the P-type detection unit 25p are connected to the second base portion 68b, while the movable electrode group 20c of the P-type detection unit 26p and the movable electrode group 20d of the N-type detection unit 26n are connected to the first base portion 68a.

[0065] According to this, since the first base 68a, which includes four detection units, and the second base 68b, which also includes four detection units, are arranged symmetrically with respect to the center line 60 as the axis of symmetry, the left and right weight balance of the movable body 8c can be made uniform. Furthermore, since the first base 68a and the second base 68b each have four detection units, and a total of eight detection units are provided, the sensitivity of acceleration detection is further increased. Therefore, the accelerometer 130 has good weight balance with the movable body 8c and high detection accuracy. Therefore, it is possible to provide an acceleration sensor 130 in which multi-axis sensitivity is suppressed and detection accuracy is high.

[0066] Embodiment 5 ***Different forms of sensor elements - 4*** Figure 10 is a plan view of the sensor element according to Embodiment 5, and corresponds to Figures 1 and 9. The configuration described in Embodiment 4 above, in which detection units are provided on both sides of the first base 68a and the second base 68b, can also be applied to a structure in which a movable part is supported by a single support arm. Hereafter, the same parts as in the above embodiment will be numbered, and redundant explanations will be omitted.

[0067] As shown in Figure 10, the acceleration sensor 140 of this embodiment employs a configuration in which the movable body 86 is supported by a single support arm 66, similar to the configuration in Figure 8. In the acceleration sensor 140, the sensor element 54 is supported by two fixing parts: a first fixing part 43a and a second fixing part 43b. In other words, the fixing part has a first fixing part 43a and a second fixing part 43b spaced apart from the first fixing part 43a in the opposite direction from the first direction. The support beam includes a first rotating spring 64a as a first support beam, with one end fixed to the first fixing part 43a and extending in the X-minus direction opposite to the first direction, and a second rotating spring 64b as a second support beam, with one end fixed to the second fixing part 43b and extending in the X-plus direction.

[0068] The support arm 66 is a connecting part, provided on the center line 60 and extending in the Y direction. One end of the support arm 66 is connected to the other end of the first rotary spring 64a and the other end of the second rotary spring 64b. The other end of the support arm 66 is connected to the center of the weight beam 78. The weight beam 78 is a weight member that increases the moment of inertia of the movable body 86 and is a plate-shaped member that extends in the X direction. The support arm 66 is provided with a first base 69a that branches off from the support arm 66 in the X-positive direction and a second base 69b that branches off in the X-minus direction. The first base 69a and the second base 69b are provided symmetrically with respect to the center line 60 as the axis of symmetry. In other words, the movable body 86 has a first base 69a that is connected to the support arm 66 and extends in the X-positive direction, and a second base 69b that is connected to the support arm 66 and extends in the X-minus direction opposite to the first direction.

[0069] The second base 69b is provided with an N-type detection unit 25n and a P-type detection unit 25p in that order, starting from the negative side of the X-axis. axis On the positive side, an N-type detection unit 25n and a P-type detection unit 25p are provided in that order, starting from the negative side of the X-axis. In other words, the second base 69b has four detection units on both sides in the Y direction, consisting of two N-type detection units 25n and two P-type detection units 25p. On the negative side of the Y-axis of the first base 69a, a P-type detection unit 26p and an N-type detection unit 26n are provided in that order, starting from the support arm 66 side. Similarly, on the positive side of the Y-axis, a P-type detection unit 26p and an N-type detection unit 26n are provided in that order, starting from the support arm 66 side. In other words, the first base 69a has four detection units on both sides in the Y direction, consisting of two P-type detection units 26p and two N-type detection units 26n.

[0070] Thus, the first base 69a, which includes four detection units, and the second base 69b, which also includes four detection units, are arranged symmetrically with respect to the center line 60 as the axis of symmetry. It should be noted that the arrangement is not limited to providing detection units on both sides of the first base 69a and the second base 69b; a symmetrical configuration is sufficient, and detection units may be provided on only one side. In other words, the movable electrode group 20a of the N-type detection unit 25n and the movable electrode group 20b of the P-type detection unit 25p are connected to the second base 69b, while the movable electrode group 20c of the P-type detection unit 26p and the movable electrode group 20d of the N-type detection unit 26n are connected to the first base 69a.

[0071] As described above, the acceleration sensor 140 as a physical quantity sensor in this embodiment provides the following effects in addition to those of the above embodiment. According to the acceleration sensor 140, the fixed part has a first fixed part 43a and a second fixed part 43b spaced apart from the first fixed part 43a in the direction opposite to the first direction, the support beam has a first rotating spring 64a as a first support beam with one end fixed to the first fixed part 43a and extending in the X-minus direction opposite to the first direction, and a second rotating spring 64b as a second support beam with one end fixed to the second fixed part 43b and extending in the X-plus direction, and the movable body 86 has one end fixed to the other end of the first fixed part 43a and the second fixed part 43b The device has a support arm 66 connected to the other end and extending in the Y-plus direction as a connecting part, a first base 69a connected to the support arm 66 and extending in the X-plus direction, and a second base 69b connected to the support arm 66 and extending in the X-minus direction opposite to the first direction. The movable electrode group 20a of the N-type detection unit 25n and the movable electrode group 20b of the P-type detection unit 25p are connected to the second base 69b, and the movable electrode group 20c of the P-type detection unit 26p and the movable electrode group 20d of the N-type detection unit 26n are connected to the first base 69a.

[0072] According to this, since the first base 69a, which includes four detection units, and the second base 69b, which also includes four detection units, are arranged symmetrically with respect to the center line 60 as the axis of symmetry, the left-right weight balance of the movable body 86 can be made uniform. Furthermore, since the first base 69a and the second base 69b each have four detection units, and a total of eight detection units are provided, the sensitivity of acceleration detection is further increased. Therefore, the accelerometer 140 has good weight balance with the movable body 86 and high detection accuracy. Therefore, it is possible to provide an acceleration sensor 140 with suppressed sensitivity in other axes and high detection accuracy.

[0073] Embodiment 6 ***Variable thicknesses of movable and fixed electrodes*** Figure 11 is an explanatory diagram of the acceleration detection principle according to Embodiment 6, and corresponds to Figure 5. In the above embodiment, it was explained that in the initial state, the positions of the ends of the fixed electrode 11 and movable electrode 21 of the N-type detection unit 25n on the Z-minus side, and the positions of the ends of the fixed electrode 12 and movable electrode 22 of the P-type detection unit 25p on the Z-minus side, are the same. However, the configuration is not limited to this, and they do not have to be the same. Hereafter, the same parts as in the above embodiment will be numbered, and redundant explanations will be omitted.

[0074] In this embodiment, in the initial state, the position of the end of the movable electrode 21 of the N-type detection unit 25n on the Z-minus side protrudes by a dimension d compared to the position of the end of the fixed electrode 11. Furthermore, in the P-type detection unit 25p, the position of the end of the fixed electrode 12 on the Z-minus side protrudes by a dimension d compared to the position of the end of the movable electrode 22. In other words, compared to the initial state in Figure 5, the positions of the movable electrode 21 and the fixed electrode 12 have shifted by a dimension d in the Z-minus direction. The rest of the configuration is the same as described in Embodiment 1.

[0075] When acceleration occurs in the Z-positive direction, the movable electrode 21 of the N-type detection unit 25n and the movable electrode 22 of the P-type detection unit 25p are displaced to the Z-negative side due to the inertial force associated with the acceleration. At this time, the overlapping area between the fixed electrode 11 and the movable electrode 21 in the N-type detection unit 25n becomes smaller than the initial area due to the displacement of the movable electrode 21 in the Z-negative direction. In other words, the capacitance decreases. On the other hand, the overlapping area between the fixed electrode 12 and the movable electrode 22 in the P-type detection unit 25p becomes larger than the initial area due to the displacement of the movable electrode 22 in the Z-minus direction. In other words, the capacitance increases. In the configuration of Figure 5, no change in the overlapping area occurred in the P-type detection unit, but according to the configuration of this embodiment, acceleration can be detected in the P-type detection unit as well. In other words, since detection can be performed in the P-type detection unit in addition to the N-type detection unit, more accurate detection can be achieved.

[0076] Next, when acceleration occurs in the Z-negative direction, the movable electrode 21 of the N-type detection unit 25n and the movable electrode 22 of the P-type detection unit 25p are each displaced to the Z-positive side due to the inertial force associated with the acceleration. At this time, the overlapping area between the fixed electrode 11 and the movable electrode 21 in the N-type detection unit 25n becomes larger than the initial area due to the displacement of the movable electrode 21 in the Z-positive direction. In other words, the capacitance increases. In the configuration of Figure 5, no change in overlapping area occurred in the N-type detection unit, but according to the configuration of this embodiment, acceleration can also be detected in the N-type detection unit. In other words, since detection can be performed in the N-type detection unit in addition to the P-type detection unit, higher accuracy detection can be achieved. On the other hand, the overlapping area between the fixed electrode 12 and the movable electrode 22 in the P-type detection unit 25p becomes smaller than the initial area as the movable electrode 22 is displaced in the Z-positive direction.

[0077] Thus, according to the configuration of this embodiment, when acceleration occurs in the Z-positive direction, the overlapping area of ​​the N-type detection unit 25n decreases, and the overlapping area of ​​the P-type detection unit 25p increases. Furthermore, when acceleration occurs in the Z-negative direction, the overlapping area of ​​the N-type detection unit 25n increases, and the overlapping area of ​​the P-type detection unit 25p decreases. This makes it possible to detect acceleration regardless of whether the acceleration is applied in the Z-positive or Z-negative direction, using the P-type and N-type detection units at both poles, enabling more accurate detection. Although the above description concerns the application of the configuration shown in Figure 11 to the acceleration sensor 100, it is also applicable to the acceleration sensors 110, 120, 130, and 140 of other embodiments, and similar effects can be obtained.

[0078] Embodiment 7 ***Inertial Measurement Device*** Figure 12 is an exploded perspective view of the inertial measuring device according to Embodiment 7. Figure 13 is a perspective view of the circuit board. Next, an example of the inertial measuring device 200 of this embodiment will be described using Figures 12 and 13.

[0079] As shown in Figure 12, the inertial measurement device 200 is an IMU (Inertial Measurement Unit) that detects inertial momentum, such as the attitude and behavior of moving objects like automobiles and robots. The object to which it is attached is not limited to moving objects like automobiles; it can also be a structure such as a bridge or elevated railway track. When attached to a structure, it is used as a structural health monitoring system to check the structural integrity of the building. The inertial measurement device 200 is a so-called 6-axis motion sensor equipped with an acceleration sensor that detects acceleration in the direction along the three axes and an angular velocity sensor that detects angular velocity around the three axes.

[0080] The inertial measuring device 200 is a rectangular prism with a roughly square shape in plan view. Screw holes 211 are formed near two vertices located diagonally across the square. The inertial measuring device 200 can be fixed to the mounting surface of an object such as an automobile by passing two screws through these two screw holes 211. 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 200 comprises an outer case 210, a connecting member 220, and a sensor module 230. The sensor module 230 is inserted into the outer case 210 with the connecting member 220 interposed between them. The sensor module 230 has an inner case 231 and a circuit board 232. The inner case 231 is provided with a recess 231a to prevent contact with the circuit board 232 and an opening 231b to expose a connector 233, which will be described later. The circuit board 232 is bonded to the lower surface of the inner case 231 via adhesive.

[0082] As shown in Figure 13, the top surface of the circuit board 232 is equipped with a connector 233, an angular velocity sensor 234z for detecting angular velocity around the Z axis, and an acceleration sensor unit 235 for detecting acceleration in the X, Y, and Z axes. Furthermore, an angular velocity sensor 234x for detecting angular velocity around the X axis and an angular velocity sensor 234y for detecting angular velocity around the Y axis are mounted on the side of the circuit board 232.

[0083] The acceleration sensor unit 235 includes at least the acceleration sensor 100 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. Alternatively, acceleration sensors 110, 120, 130, and 140 may be used instead of acceleration sensor 100. The angular velocity sensors 234x, 234y, and 234z are not particularly limited, but for example, a vibration gyro sensor utilizing the Coriolis force can be used.

[0084] A control IC 236, which functions as the control unit, is mounted on the underside of the circuit board 232. The control IC 236 is, for example, an MCU (Microcontroller Unit) and incorporates a memory unit including non-volatile memory and an A / D converter, and controls various parts of the inertial measurement device 200. The memory unit stores a program that defines the order and content for detecting acceleration and angular velocity, an inspection program that defines the inspection method for the detection function of the acceleration sensor 100, and associated data. In addition, several other electronic components are mounted on the circuit board 232. In other words, the inertial measurement device 200 is composed of an acceleration sensor 100 as a physical quantity sensor and a control IC 236 as a control unit that performs control based on the detection signal output from the acceleration sensor 100.

[0085] Furthermore, the inertial measurement device 200 is not limited to the configurations shown in Figures 12 and 13. For example, it may be configured to include only the acceleration sensor 100 as a physical quantity sensor, without the angular velocity sensors 234x, 234y, and 234z. In this case, for example, the acceleration sensor 100 and the control IC 236 can be configured as a single mounting package, thereby providing the inertial measurement device 200 as a single chip component.

[0086] As described above, the inertial measuring device 200 of this embodiment provides the following effects in addition to the effects of the above embodiment. The inertial measurement device 200 includes an acceleration sensor 100 as a physical quantity sensor and a control IC 236 as a control unit that performs control based on the detection signal output from the acceleration sensor 100.

[0087] According to this, the inertial measurement device 200 is equipped with an acceleration sensor 100 that suppresses sensitivity in other axes and has high detection accuracy. Therefore, it is possible to provide an inertial measurement device 200 with high detection accuracy and excellent reliability. [Explanation of symbols]

[0088] 1...Base, 1b...Recess, 1c...Protruding part, 2...Embedded insulating layer, 3...Fixed part, 4a...First rotating spring, 4b...Second rotating spring, 5...Lid, 5b...Recess, 6a...First connecting part, 6b...Second connecting part, 7...Base, 8,8b,8c...Movable part, 9a~9d...Base part, 10...Fixed electrode part, 10a~10d...Fixed electrode group, 11,11c...Fixed electrode, 12,12c...Fixed electrode, 13...Glass frit, 14...Mount part, 17...Connecting beam, 19...Fixed electrode part, 20...Movable electrode part, 20a~20d...Movable electrode group, 2 1,21c…Movable electrode, 22,22c…Movable electrode, 25n…N-type detection unit, 25p…P-type detection unit, 26n…N-type detection unit, 26p…P-type detection unit, 29…Movable electrode unit, 30a…Damper movable unit, 30b…Damper movable unit, 31a,31b…First bar, 32…Second bar, 33a,33b…Electrode shaft, 34,35…Connecting unit, 41,42,44…Connecting pad, 43a…First fixing unit, 43b…Second fixing unit, 45a,45b…Damper fixing unit, 46…Third bar, 47…Connecting unit, 50,52,53,54 ...sensor element, 60...center line, 61...oscillation axis, 64a...first rotation spring, 64b...second rotation spring, 65a,65b...damper section, 66...support arm, 68a...first base, 68b...second base, 69a...first base, 69b...second base, 70a,70b...movable electrode group, 71,72,74...wiring, 75n...N-type detection unit, 75p...P-type detection unit, 76n...N-type detection unit, 76p...P-type detection unit, 77...base, 77a...first base, 77b...second base, 78...weight beam, 80a,80b...fixed electrode group, 85,8 6, 89…Movable body, 90…Accelerometer of comparative example, 100, 110, 120, 130, 140…Accelerometer, 200…Inertial measurement device, 210…Outer case, 211…Screw hole, 220…Jointing member, 230…Sensor module, 231…Inner case, 231a…Recess, 231b…Opening, 232…Circuit board, 233…Connector, 234x…Angular velocity sensor, 234y…Angular velocity sensor, 234z…Angular velocity sensor, 235…Accelerometer unit, 236…Control IC.

Claims

1. When the mutually orthogonal directions are designated as the first direction, the second direction, and the third direction, A fixing part fixed to the base, A support beam, one end of which is connected to the fixed part, A fixed electrode portion provided on the substrate, Movable body and, Includes, The aforementioned fixed electrode portion is The first fixed electrode group, The second fixed electrode group, The third fixed electrode group, The fourth fixed electrode group, Includes, The movable body includes a movable electrode portion, The movable electrode portion is A first movable electrode group including a first movable electrode facing the first fixed electrode of the first fixed electrode group described above, A second movable electrode group including a second movable electrode facing the second fixed electrode of the second fixed electrode group, A third movable electrode group including a third movable electrode facing the third fixed electrode of the third fixed electrode group, A fourth movable electrode group including a fourth movable electrode facing the fourth fixed electrode of the aforementioned fourth fixed electrode group, Includes, The first movable electrode group, the second movable electrode group, the third movable electrode group, and the fourth movable electrode group are arranged in order along the first direction. In the third direction, The thickness of the second movable electrode and the thickness of the third movable electrode are, Unlike the thickness of the first movable electrode and the thickness of the fourth movable electrode, When the imaginary line extending from the center of the fixed portion in the second direction is taken as the axis of symmetry, The first movable electrode is arranged symmetrically with respect to the fourth movable electrode. The second movable electrode is positioned symmetrically with respect to the third movable electrode. Physical quantity sensor.

2. The aforementioned support beam is A first support beam, one end of which is fixed to the fixing part and extending in the first direction, A second support beam, one end of which is fixed to the fixing part and extending in a direction opposite to the first direction, Includes, The aforementioned movable body is A first connecting portion, one end of which is connected to the other end of the first support beam and extending in the second direction, A second connecting portion, one end of which is connected to the other end of the second support beam and extending in the second direction, A base portion connecting the first connecting portion and the second connecting portion, extending in the first direction, Includes, The first movable electrode group, the second movable electrode group, the third movable electrode group, and the fourth movable electrode group are connected to the base. The physical quantity sensor according to claim 1.

3. The aforementioned fixing part is First fixing part and A second fixing portion is positioned spaced apart from the first fixing portion in a direction opposite to the first direction, Includes, The aforementioned support beam is A first support beam, one end of which is fixed to the first fixing part and extending in a direction opposite to the first direction, A second support beam, one end of which is fixed to the second fixing part and extending in the first direction, Includes, The aforementioned movable body is A connecting portion having one end connected to the other end of the first support beam and the other end of the second support beam, extending in the second direction, A first base portion is connected to the other end of the aforementioned connecting portion and extends in the first direction, A second base portion is connected to the other end of the aforementioned connecting portion and extends in a direction opposite to the first direction, Includes, The first movable electrode group and the second movable electrode group are connected to the second base, The third movable electrode group and the fourth movable electrode group are connected to the first base. The physical quantity sensor according to claim 1.

4. The aforementioned support beam is A first support beam, one end of which is fixed to the fixing part and extending in the first direction, A second support beam, one end of which is fixed to the fixing part and extending in a direction opposite to the first direction, Includes, The aforementioned movable body is A first connecting portion, one end of which is connected to the other end of the first support beam and extending in the second direction, A second connecting portion, one end of which is connected to the other end of the second support beam and extending in the second direction, A first base portion extending from the first connecting portion in a direction opposite to the first direction, A second base portion extending in the first direction from the second connecting portion, Includes, The first movable electrode group and the second movable electrode group are connected to the second base, The third movable electrode group and the fourth movable electrode group are connected to the first base. The physical quantity sensor according to claim 1.

5. The aforementioned fixing part is First fixing part and A second fixing portion is positioned spaced apart from the first fixing portion in the direction opposite to the first direction, Includes, The aforementioned support beam is A first support beam, one end of which is fixed to the first fixing part and extending in a direction opposite to the first direction, A second support beam, one end of which is fixed to the second fixing part and extending in the first direction, Includes, The aforementioned movable body is A connecting portion having one end connected to the other end of the first support beam and the other end of the second support beam, extending in the second direction, A first base portion connected to the connecting portion and extending in the first direction, A second base portion connected to the aforementioned connecting portion and extending in a direction opposite to the first direction, Includes, The first movable electrode group and the second movable electrode group are connected to the second base, The third movable electrode group and the fourth movable electrode group are connected to the first base. The physical quantity sensor according to claim 1.

6. A physical quantity sensor according to any one of claims 1 to 5, A control unit that performs control based on the detection signal output from the physical quantity sensor, including, Inertial measuring device.

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