WO2015033522A1

WO2015033522A1 - Strain sensor

Info

Publication number: WO2015033522A1
Application number: PCT/JP2014/004251
Authority: WO
Inventors: 佳光池山; 中西　努; 昌也競
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2013-09-06
Filing date: 2014-08-20
Publication date: 2015-03-12

Abstract

In the present invention, a first strain sensor has: a support substrate having a stationary section; an oscillating beam connected to the stationary section; and a first arm and second arm connected to the oscillating beam. The first end of the first arm is connected to the first surface of the oscillating beam, the first arm is separated from the support substrate, the first end of the second arm is connected to the second surface of the oscillating beam, and the second arm is separated from the support substrate. Also, a second strain sensor has: an oscillating beam; a stationary section connected to the oscillating beam; a first arm of which the first end is connected to the first surface of the oscillating beam and the second end is a free end; and a second arm of which the first end is connected to the second surface of the oscillating beam and the second end is a free end.

Description

Strain sensor

The present invention relates to a strain sensor that detects strain and load acting on an object.

Generally, sensors that detect strain, load, and pressure acting on an object are used for various control devices, home appliances, information devices, automobile engines, suspension control, and the like.

A conventional pressure sensor includes a pressure sensor element including a piezoelectric vibration piece in a bending vibration mode and a pressure receiving member such as a diaphragm for receiving pressure from the outside, and the pressure sensor element is disposed at both ends in the longitudinal direction of the piezoelectric vibration piece. In the pressure sensor supported by the base end, vibration leakage to the outside of the piezoelectric vibrating piece is suppressed (Patent Document 1). In addition, techniques such as Patent Documents 2 to 5 are disclosed.

JP 2011-95188 A JP 2012-177619 A JP 2011-217348 A JP 2010-243468 A JP 61-30735 A

A strain sensor according to the present invention includes a support substrate having a fixed portion, a vibrating beam connected to the fixed portion, a first arm and a second arm connected to the vibrating beam, and a first arm in the first arm. One end is connected to the first surface of the vibrating beam, the first arm is spaced from the support substrate, the first end of the second arm is connected to the second surface of the vibrating beam, The second arm is separated from the support substrate.

As described above, since the vibrating beam has the first arm and the second arm that are separated from the support substrate, productivity can be improved by adopting a simple configuration. Moreover, vibration leakage can be reduced.

Top view of the strain sensor of the first embodiment A-A 'sectional view of the strain sensor shown in FIG. 1A B-B 'sectional view of the strain sensor shown in FIG. 1A The figure which shows the drive of the distortion sensor of Embodiment 1. Top view of the strain sensor of the second embodiment A-A 'sectional view of the strain sensor shown in FIG. 3A B-B 'sectional view of the strain sensor shown in FIG. 3A The graph which shows the effect of the vibration leak of the distortion sensor of Embodiment 2 Top view of strain sensor of embodiment 3 A-A 'sectional view of the strain sensor shown in FIG. 5A B-B 'sectional view of the strain sensor shown in FIG. 5A Top view of strain sensor of embodiment 4 A-A 'sectional view of the strain sensor shown in FIG. 6A B-B 'sectional view of the strain sensor shown in FIG. 6A Top view of strain sensor of embodiment 5 A-A 'sectional view of the strain sensor shown in FIG. 7A B-B 'sectional view of the strain sensor shown in FIG. 7A Top view of the strain sensor according to the sixth embodiment A-A 'sectional view of the strain sensor shown in FIG. 8A B-B 'sectional view of the strain sensor shown in FIG. 8A C-C 'sectional view of the strain sensor shown in FIG. 8A

Prior to the description of the embodiment of the present invention, problems in the conventional strain sensor will be described. The conventional strain sensor disclosed in Patent Document 1 cannot sufficiently reduce vibration leakage. In addition, providing a thin portion results in a complicated configuration and increases the number of production steps, thus reducing productivity.

Hereinafter, a strain sensor according to an embodiment of the present invention that sufficiently reduces vibration leakage and improves productivity will be described.

(Embodiment 1)
The strain sensor 31 according to the first embodiment will be described with reference to the drawings.

1A to 1C are diagrams showing a strain sensor 31 according to the first embodiment. The strain sensor 31 is formed by etching a semiconductor substrate such as silicon and the like, and includes

fixed portions

33a and 33b connected to the support substrate 32, and a vibrating beam 34 whose longitudinal ends are supported by the

fixed portions

33a and 33b. The first arm 36 having one end (first end) connected to one surface (first surface) 35 in the lateral direction of the vibrating beam 34 and the other side of the vibrating beam 34 in the lateral direction. A second arm 38 having one end (first end) connected to the surface (second surface) 37 is provided. The first arm 36 is perpendicular to the extending direction of the vibrating beam 34 and has a first portion connected to the vibrating beam 34, and the first arm 36 is parallel to the extending direction of the vibrating beam 34, A second portion connected to the first portion; The second arm 38 has the same configuration as that of the first arm 36. Here, in the first embodiment, it is preferable to provide the first arm 36 and the second arm 38 at positions symmetrical to the vibrating beam 34 so as to face the vibrating beam 34. More specifically, the first arm 36 and the second arm 38 are preferably arranged so as to be line symmetric with respect to the extending direction of the vibrating beam 34. “Symmetry” includes “substantially symmetric” including a range of design errors. The same applies hereinafter. With this configuration, the balance between the first arm 36 (the first portion of the first arm 36) and the second arm 38 (the first portion of the second arm 38) in the short direction of the vibrating beam 34 is balanced. The vibration of the vibrating beam 34 can be stabilized. In the first embodiment, the

fixing portions

33a and 33b are provided at both ends of the vibrating beam 34. However, the

fixing portions

33a and 33b are not limited to this, and may be formed in a rectangular shape so as to surround the vibrating beam 34. May be.

A drive unit 40 is provided at the end of a surface 39 different from one surface (first surface) 35 and the other surface (second surface) 37 of the vibration beam 34, and a detection unit 41 is provided at the center. ing. Thus, although it is preferable that the drive part 40 and the detection part 41 are arrange | positioned on the same surface (3rd surface), it is not limited to this. For example, they may be arranged on different surfaces. Here, it is preferable that the drive part 40 is arrange | positioned in the connection part vicinity of the vibrating beam 34 and the fixing | fixed part 33b. For example, the drive unit 40 is disposed between a first connection point where the first arm 36 and the vibrating beam 34 are connected and a second connection point where the second arm 38 and the vibrating beam 34 are connected. It can be considered. The drive unit 40 is provided on a lower electrode formed of a metal material such as platinum, a piezoelectric layer provided on the lower electrode and formed of a piezoelectric material such as lead zirconate titanate, and the piezoelectric layer. The upper electrode is made of a metal material such as gold. When a voltage is applied to the drive unit 40, the piezoelectric layer expands and contracts due to the inverse piezoelectric effect, the piezoelectric body is bent and displaced in a direction perpendicular to the surface, and the vibrating beam 34 vibrates in the thickness direction.

Similarly to the driving unit 40, the detection unit 41 includes a lower electrode formed of a metal material such as platinum, a piezoelectric layer provided on the lower electrode and formed of a piezoelectric material such as lead zirconate titanate, The upper electrode is provided on the body layer and is formed of a metal material such as gold. When a voltage is applied to the driving unit 40 and the vibrating beam 34 vibrates, an AC signal corresponding to the natural frequency f of the vibrating beam 34 is input to a processing circuit (not shown) connected to the detecting unit 41 by the piezoelectric effect. The The AC signal input to the processing circuit is phase-adjusted and amplified in the processing circuit and fed back to the drive unit. Thereby, the vibrating beam 34 continues the string vibration at a frequency equal to the natural frequency f.

When strain is generated by an external force applied to the support substrate 32 provided with the strain sensor 31, the strain is transmitted to the vibrating beam 34 through the

fixing portions

33a and 33b. Here, when a tensile force F is applied to the support substrate 32 in the direction in which the vibrating beam 34 expands and contracts, the stretching force acts on the vibrating beam 34 to develop a stress stiffening effect and the vibrating beam 34 is cured. The vibration frequency of the sensor 31 increases from f to f + Δf. In this way, by measuring the output natural frequency difference Δf, the strain and load acting on the support substrate 32 can be measured with high sensitivity.

Further, if a compressive force −F in the longitudinal direction of the vibrating beam 34 is applied to the support substrate 32, a stress stiffening effect that softens the vibrating beam 34 appears in contrast to when a tensile force is applied. The vibration frequency of the sensor 31 decreases from f to f−Δf.

The strain sensor 31 configured as described above measures a strain generated by an external force applied to the support substrate 32 while applying a voltage to the drive unit 40 and vibrating the vibrating beam 34. For this reason, although the vibration of the vibrating beam 34 leaks from the connecting portion between the vibrating beam 34 and the fixing

portions

33a and 33b to the support substrate 32 via the fixing

portions

33a and 33b, the detection accuracy is lowered. In the strain sensor 31 according to the first embodiment, the first arm 36 and the second arm 38 are provided on the vibration beam 34, whereby vibration leakage to the support substrate 32 can be reduced.

The first arm 36 and the second arm 38 are separated from the support substrate 32, and the end on the side not connected to the vibrating beam 34 is a free end. FIG. 2 shows the movement of the first arm 36 and the second arm 38 when the vibrating beam 34 is vibrating. As shown in FIG. 2, the first arm 36 and the second arm 38 are arranged on the concave side of the bending of the vibrating beam 34 which is curved by vibrating according to the vibration of the vibrating beam 34. The arm 38 swings. As shown in FIG. 2, when the vibrating beam 34 is displaced upward, the first arm 36 and the second arm 38 are displaced downward, and when the vibrating beam 34 is displaced downward, the first arm 36 is displaced. The second arm 38 is displaced upward, and the first arm 36 and the second arm 38 vibrate in an opposite phase to the vibration direction of the vibrating beam 34. For this reason, in the connection part of the vibrating beam 34, the 1st arm 36, and the 2nd arm 38, it is comprised so that the sum of the momentum of the vibrating beam 34 and the momentum of the 1st arm 36 and the 2nd arm 38 may become equal. As a result, the vibration of the vibrating beam 34 and the vibrations of the first arm 36 and the second arm 38 cancel each other, so that the vibration of the vibrating beam 34 is not transmitted to the fixed

portions

33a and 33b, but is transmitted to the fixed

portions

33a and 33b. Vibration leakage can be reduced.

It is not the same structure as that of the first embodiment, and for example, the first arm 36 and the second arm 38 are provided in a direction substantially orthogonal to the longitudinal direction of the vibrating beam 34 without bending the central portion of the vibrating beam 34. However, the effects of the first embodiment can be obtained if the first arm 36 and the second arm 38 vibrate with a component opposite to the direction of movement of the vibrating beam 34. However, the amplitude of the vibrating beam 34 is maximum at the central portion, and the amplitude becomes smaller as it is closer to the connecting portion to the fixing

portions

33a and 33b. Therefore, when the first arm 36 and the second arm 38 are provided at the central portion, Large energy is required to vibrate the first arm 36 and the second arm 38. On the other hand, the first arm 36 and the second arm 38 can be vibrated with less energy by providing the first arm 36 and the second arm 38 in the vicinity of the connecting portion having a small amplitude of the vibrating beam 34. Further, since the first arm 36 and the second arm 38 can be bent, the size can be reduced.

Further, a weight may be provided at the other end of the first arm 36 and the second arm 38 of the first embodiment that are not connected to the vibrating beam 34. By providing weights at the other ends of the first arm 36 and the second arm 38, the natural frequencies of the first arm 36 and the second arm 38 can be easily adjusted, and the size can be further reduced. .

(Embodiment 2)
The strain sensor 51 according to the second embodiment will be described with reference to the drawings.

In the strain sensor according to the second embodiment, the same reference numerals as those in the first embodiment may be attached to the same structures as those in the first embodiment. In the following description, differences from the first embodiment will be mainly described. The strain sensor according to the second embodiment is different from the first embodiment in that the third arm and the fourth arm are further provided on the vibrating beam 34.

3A to 3C show the strain sensor 51 of the second embodiment. The strain sensor 51 is formed by etching a semiconductor substrate such as silicon, and has a rectangular fixed portion 53 connected to the support substrate 32, a vibrating beam 34 supported at both ends by the fixed portion 53, and the vibrating beam 34. The first arm 36 is connected to one surface (first surface) 35 of the first, and the second arm 38 is connected to the other surface (second surface) 37 of the vibrating beam. A third arm 54 and a fourth arm 55 are provided on the opposite side of the vibrating beam 34 from the side where the first arm 36 and the second arm 38 are provided. Similarly to the first arm 36 and the second arm 38, the third arm 54 and the fourth arm 55 are separated from the support substrate 32, and the end not connected to the vibrating beam 34 is a free end. It has become. The first arm 36, the second arm 38, the third arm 54, and the fourth arm 55 are preferably separated from the fixing portion 53. The fixing portion 53 has a first part connected to both ends of the vibrating beam 34 and a second part parallel to the extending direction of the vibrating beam 34. The second part is connected to the first part via the slit. The arm 36 and the second arm 38 are preferably located outside. The distance between the free end of the first arm 36 and the free end of the third arm 54 is the same as the distance between the free end of the second arm 38 and the free end of the fourth arm 55. It is preferable that Here, “same” includes “substantially the same” within the range of the design error. Further, the first arm 36 and the fourth arm 55 are arranged so as to be point-symmetric with respect to the center of the vibrating beam 34, and the second arm 38 and the third arm 54 are set with respect to the center of the vibrating beam 34. Are preferably arranged so as to be point-symmetric. The first arm 36, the third arm 54, the second arm 38, and the fourth arm 55 are preferably arranged so as to be line symmetric with respect to the extending direction of the vibrating beam 34.

In the first embodiment, the vibration leakage is reduced by providing the first arm 36 and the second arm 38, but the strain sensor 51 of the second embodiment has a configuration as shown in FIGS. 3A to 3C. By providing the third arm 54 and the fourth arm 55, vibration leakage is further reduced. As shown in FIGS. 3A to 3C, by providing the first arm 36, the second arm 38, the third arm 54, and the fourth arm 55 in the vicinity of both ends of the vibrating beam 34, both ends of the vibrating beam 34 are provided. Since the arm is provided, vibration leakage from both ends of the vibration beam 34 to the fixed portion 53 can be reduced. In the strain sensor 51 of the second embodiment, vibration leakage to the fixed portion 53 is free from the bent portions of the first arm 36, the second arm 38, the third arm 54, and the fourth arm 55 with respect to the vibration beam 34. The length L to the other end, which is the end, was changed with respect to the length of the vibrating beam 34, and evaluation was performed using a dynamic analysis (for example, modal analysis) of the finite element method. As a result of this evaluation, the arm length L when the first arm 36, the second arm 38, the third arm 54, and the fourth arm 55 are not provided is set to 0, and vibration leakage to the fixed portion is reduced to L. FIG. 4 shows a graph normalized with 1 when = 0. As shown in FIG. 4, when the first arm 36, the second arm 38, the third arm 54, and the fourth arm 55 are provided, the length L of the arm is about 22% of the length of the vibrating beam 34. And the first arm 36, the second arm 38, the third arm 54, and the fourth arm 55 provide the leakage vibration from the vibrating beam 34 to the fixed portion 53. The reduction effect could be confirmed. Further, when the arm length L is about 24% of the length of the vibrating beam 34, the leakage vibration is 0.25, and when the arm length L is about 28%, the leakage vibration is 0.21, which is particularly effective. The effect was greatest when L was about 26%, and vibration leakage to the fixed portion 53 was 0.01 or less. Further, the leakage vibration is about 0.39 when the length L is about 30%. Therefore, the length L of the arm is preferably about 20% or more and about 30% or less of the length of the vibrating beam 34. Furthermore, the length L of the arm is preferably not less than about 24% and not more than about 28% of the length of the vibrating beam 34.

Further, by providing the third arm 54 and the fourth arm 55 at positions that are symmetrical with the first arm 36 and the second arm 38 with respect to the longitudinal center portion of the vibration beam 34, the vibration beam The balance in the longitudinal direction of 34 is improved. If the balance of the weight in the longitudinal direction of the vibrating beam 34 is poor, the vibrating beam 34 vibrates in the rotational direction in addition to the vertical vibration, so that the detection accuracy of the strain sensor 51 is reduced. The vibration leakage can be reduced without lowering.

(Embodiment 3)
A strain sensor 61 according to Embodiment 3 will be described with reference to the drawings.

In the strain sensor 61 of the third embodiment, the same structure as that of the first and second embodiments may be denoted by the same reference numerals as those of the first and second embodiments. In the following, differences from the first embodiment and the second embodiment will be mainly described. The strain sensor 61 according to the third embodiment is different from the first embodiment in that both ends of the first arm and the second arm are connected to the vibrating beam.

5A to 5C are diagrams showing the strain sensor 61 according to the third embodiment. The strain sensor 61 is formed by etching a semiconductor substrate such as silicon, and includes a rectangular fixed portion 53 connected to the support substrate 32, a vibrating beam 34 supported at both ends by the fixed portion 53, and the vibrating beam 34. It has a first arm 66 connected to one surface (first surface) 35 and a second arm 68 connected to the other surface (second surface) 37 of the vibrating beam. The first arm 66 and the second arm 68 are respectively connected to the vibrating beam 34 at both ends, and the central portion is separated from the support substrate 32 and the vibrating beam 34. The third embodiment is different from the first and second embodiments in that both ends are connected to the vibrating beam 34, and therefore both ends of the first arm 66 and the second arm 68 are fixed ends.

When the strain is applied to the support substrate 32, the strain sensor 61 expands and contracts in the longitudinal direction, so that the vibration frequency f of the vibration beam 34 changes to f ± Δf. The magnitude of distortion applied to the is detected. As shown in FIG. 4, the strain sensor 61 according to the third embodiment has both ends connected to the vibrating beam 34. Therefore, strain is applied to the support substrate 32, the vibrating beam 34 expands and contracts, and the natural frequency changes. In this case, both the first arm 66 and the second arm 68 extend and contract in the longitudinal direction of the vibrating beam 34 in the same manner as the vibrating beam 34. Since the natural frequencies of the first arm 66 and the second arm 68 are designed in accordance with the natural frequency of the vibrating beam 34, the amplitude decreases when the natural frequency deviates greatly from this natural frequency, and the effect of reducing the leakage vibration is obtained. Although it becomes smaller, the natural frequency also changes in the same manner as that of the vibrating beam 34 as the first arm 66 and the second arm 68 expand and contract in the same manner as the vibrating beam 34. For this reason, even when a large strain is applied to the support substrate 32 and the natural frequency of the vibrating beam 34 changes greatly, the amplitude of the first arm 66 and the second arm 68 is not reduced, and the leakage vibration reducing effect is obtained. Obtainable.

(Embodiment 4)
A strain sensor 61 according to Embodiment 4 will be described with reference to the drawings.

In the strain sensor of the fourth embodiment, the same structure as in the first to third embodiments may be assigned the same reference numeral as in the first to third embodiments. In the following, parts different from the first to third embodiments will be mainly described. The strain sensor according to the fourth embodiment is different from the first embodiment in that one end (first end) of the vibrating beam 34 is connected to the fixed portion 53 via a slit 75 at a plurality of locations. 3 and different.

6A to 6C show the strain sensor 61 of the fourth embodiment. The strain sensor 61 is formed by etching a semiconductor substrate such as silicon, and both ends of the first arm 66 and the second arm 68 are connected to the side surface of the vibrating beam 34. The first arm 66 and the second arm 68 have the same thickness over the entire length, and are separated from the vibrating beam 34 through the slit 75.

6A to 6C, one end (first end) of the vibrating beam 34 is connected to the fixed portion 53 through a slit 75 at a plurality of locations. More specifically, since both ends of the vibrating beam 34 are connected to the fixing portion 53 via the slits 75, the end of the vibrating beam 34 is supported at two points. With this configuration, there is an effect that the amount of strain of the vibrating beam 34 can be increased and the sensitivity can be improved.

In FIGS. 6A to 6C, the drive unit 40 is disposed only on one end (first end) side of the first arm 66 and the second arm 68, but the drive unit 40 includes the first arm 66 and the second arm 68. 66 and the second arm 68 may be disposed at both ends.

(Embodiment 5)
A strain sensor 71 according to Embodiment 5 will be described with reference to the drawings.

In the strain sensor according to the fifth embodiment, the same reference numerals as those in the first to fourth embodiments may be attached to the same structures as those in the first to fourth embodiments. In the following, parts different from the first to fourth embodiments will be mainly described. The strain sensor according to the fifth embodiment is different from the third embodiment in that both ends of the first arm and the second arm are connected to the side surface of the vibrating beam 34 and the fixing portion 53. Yes.

7A to 7C show the strain sensor 71 of the fifth embodiment. The strain sensor 71 is formed by etching a semiconductor substrate such as silicon, and both ends of the first arm 76 and the second arm 78 are connected to the side surface of the vibrating beam 34 and the fixing portion 53. The first arm 76 and the second arm 78 have the same thickness over the entire length, and are separated from the vibrating beam 34 via the slit 75. With this configuration, there is an effect that the amount of strain of the vibrating beam 34, the first arm 76, and the second arm 78 can be increased, and the sensitivity can be improved.

Further, as shown in FIGS. 7A to 7C, it is preferable that the driving unit 40 is arranged at the center of the vibrating beam 34 and the detecting unit 41 is arranged at the end of the vibrating beam 34. Note that the lead-out wiring of the drive unit 40 may extend toward the fixed unit 53.

Further, as shown in FIGS. 7A to 7C, it is preferable that the drive unit 40 is disposed at the end of the first arm 76 and the detection unit 41 is disposed at the center of the first arm 76. Note that the lead-out wiring of the detection unit 41 may extend toward the fixed unit 53.

Further, as shown in FIGS. 7A to 7C, it is preferable that the drive unit 40 is disposed at the end of the second arm 78 and the detection unit 41 is disposed at the center of the second arm 78. Note that the lead-out wiring of the detection unit 41 may extend toward the fixed unit 53.

The arrangement relationship between the drive unit 40 and the detection unit 41 may be reversed. That is, the drive unit 40 is disposed at the end of the vibrating beam 34, the center of the first arm, and the center of the second arm, the detection unit 41 is disposed at the center of the vibrating beam 34, the end of the first arm, It may be arranged at the end of the two arms.

(Embodiment 6)
A strain sensor 71 according to the sixth embodiment will be described with reference to the drawings.

In the strain sensor of the sixth embodiment, the same reference numerals as those of the first to fifth embodiments may be attached to the same structures as those of the first to fifth embodiments. In the following, parts different from the first to fifth embodiments will be mainly described. The strain sensor according to the sixth embodiment has a structure in which a fixing portion 53 parallel to the first arm and the second arm is arranged side by side with the first arm and the second arm. This is different from the fifth embodiment.

8A to 8D show the strain sensor 71 of the fifth embodiment. The strain sensor 71 is formed by etching a semiconductor substrate such as silicon, and both ends of the first arm 76 and the second arm 78 are connected to the side surface of the vibrating beam 34 and the fixing portion 53. It is preferable that the first arm 76 and the second arm 78 have the same thickness over the entire length, and are separated from the vibrating beam 34 via the slit 75. The fixing portion 53 parallel to the first arm 76 and the second arm 78 is arranged side by side with the first arm 76 and the second arm 78. Here, the fixing portion 53 is preferably disposed outside the first arm 76 and the second arm 78 through the slit 75.

Here, it is preferable not to provide the fixing portion parallel to the first arm 76 and the second arm 78 in terms of increasing the amount of strain of the vibrating beam 34 and improving the sensitivity. However, in terms of reinforcing the strength of the vibration beam 34, the first arm 76, and the second arm 78 as a whole, it is preferable to have the fixing portion.

Further, as shown in FIGS. 8A to 8D, it is preferable that the driving unit 40 is arranged at the center of the vibrating beam 34 and the detecting unit 41 is arranged at the end of the vibrating beam 34. Note that the lead-out wiring of the drive unit 40 may extend toward the fixed unit 53.

Also, as shown in FIGS. 8A to 8D, it is preferable that the drive unit 40 is disposed at the end of the first arm 76 and the detection unit 41 is disposed at the center of the first arm 76. Note that the lead-out wiring of the detection unit 41 may extend toward the fixed unit 53.

Further, as shown in FIGS. 8A to 8D, it is preferable that the drive unit 40 is disposed at the end of the second arm 78 and the detection unit 41 is disposed at the center of the second arm 78. Note that the lead-out wiring of the detection unit 41 may extend toward the fixed unit 53.

The strain sensor of the present invention reduces the leakage of vibration from the vibrating beam to the fixed part of the support substrate, and can detect the stress applied to the support substrate with high accuracy. It is useful for various control equipment, information equipment control, automobile engine control, suspension control, and the like.

31, 51, 61, 71 Strain sensor 32

Support substrates

33a, 33b, 53 Fixed portion 34 Vibration beams 35, 37, 39

Surfaces

36, 66, 76

First arm

38, 68, 78 Second arm 40 Drive portion 41 Detection unit 54 Third arm 55 Fourth arm 75 Slit

Claims

A support substrate having a fixed portion;
A vibrating beam connected to the fixed portion;
A first arm and a second arm connected to the vibrating beam;
A first end of the first arm is connected to a first surface of the vibrating beam;
The first arm is spaced apart from the support substrate;
A first end of the second arm is connected to a second surface of the vibrating beam;
The strain sensor, wherein the second arm is separated from the support substrate.
2. The strain sensor according to claim 1, wherein the first arm and the second arm are arranged so as to be line-symmetric with respect to an extending direction of the vibrating beam.
A third arm and a fourth arm connected to the vibrating beam;
A first end of the third arm is connected to a first surface of the vibrating beam;
The third arm is spaced apart from the support substrate;
A first end of the fourth arm is connected to a second surface of the vibrating beam;
The strain sensor according to claim 1, wherein the fourth arm is separated from the support substrate.
The first arm and the fourth arm are arranged to be point-symmetric with respect to the center of the vibrating beam,
4. The strain sensor according to claim 3, wherein the second arm and the third arm are arranged so as to be point-symmetric with respect to the center of the vibrating beam.
A second end of the first arm is connected to a first surface of the vibrating beam;
The strain sensor according to any one of claims 1 to 3, wherein a second end of the second arm is connected to a second surface of the vibrating beam.
The first arm is perpendicular to the extending direction of the vibrating beam and has a first portion connected to the vibrating beam;
The first arm according to any one of claims 1 to 5, wherein the first arm includes a second portion that is parallel to an extending direction of the vibrating beam and is connected to the first portion. The strain sensor described.
The length in the extending direction of the vibrating beam in the second portion is 20% or more and 30% or less of the length in the extending direction of the vibrating beam in the vibrating beam. Strain sensor.
The length in the extending direction of the vibrating beam in the second portion is 24% or more and 28% or less of the length in the extending direction of the vibrating beam in the vibrating beam. Strain sensor.
The strain sensor according to any one of claims 1 to 8, wherein the first arm and the second arm vibrate with a component in a direction opposite to an operation direction of the vibrating beam.
In the center of the vibrating beam, a first detection unit to which a signal corresponding to the natural frequency of the vibrating beam is input is disposed,
A first driving unit to which a voltage for causing the vibrating beam to extend and contract in the thickness direction of the vibrating beam is applied to an end of the vibrating beam,
The strain sensor according to any one of claims 1 to 9, wherein the first detection unit and the first drive unit are arranged on a third surface of the vibrating beam.
The first driving unit is disposed between a first connection point where the first arm and the vibrating beam are connected and a second connection point where the second arm and the vibrating beam are connected. The strain sensor according to claim 10, wherein the strain sensor is provided.
A second detection unit to which a signal corresponding to the natural frequency of the vibrating beam is input is disposed at the end of the first arm,
In the center of the first arm, a second drive unit to which a voltage for extending and contracting the vibrating beam in the thickness direction of the vibrating beam is applied is disposed.
The strain sensor according to claim 10 or 11, wherein the second detection unit and the second drive unit are disposed on a first surface of the first arm.
The detection unit is composed of a laminated structure of a lower electrode, a piezoelectric layer, and an upper electrode,
The strain sensor according to any one of claims 10 to 12, wherein the driving unit includes a laminated structure of a lower electrode, a piezoelectric layer, and an upper electrode.
The first end of the first arm and the first end of the second arm are spaced apart from the fixing portion. Strain sensor.
The first end of the first arm and the first end of the second arm are in contact with the fixing portion. Strain sensor.
The strain sensor according to any one of claims 1 to 15, wherein the first end of the vibrating beam is connected to the fixed portion at a plurality of positions via a slit.
The fixing portion has a first portion connected to the first end and the second end of the vibrating beam, and a second portion parallel to the extending direction of the vibrating beam,
The strain sensor according to any one of claims 1 to 16, wherein the second portion is located outside the first arm and the second arm via a slit.
The strain sensor according to any one of claims 1 to 17, wherein the fixing portion is made of a semiconductor substrate.
A vibrating beam;
A fixed portion connected to the vibrating beam;
A first arm having a first end connected to the first surface of the vibrating beam and a second end being a free end;
A strain sensor comprising a second arm having a first end connected to a second surface of the vibrating beam and a second end being a free end.
The vibrating beam is
A third arm having a first end connected to the first surface of the vibrating beam and a second end being a free end;
20. The strain sensor according to claim 19, further comprising a fourth arm having a first end connected to the second surface of the vibrating beam and a second end being a free end.
The distance between the free end of the first arm and the free end of the third arm is the same as the distance between the free end of the second arm and the free end of the fourth arm. The strain sensor according to claim 20.