Vibration detection device, vital sensor, piping sensor

Abstract

This achieves both the suppression of sensitivity reduction associated with increased gaps and further improvement of sensitivity. [Solution] The vibration detection device according to the present invention comprises a plurality of vibrating parts 10A to 10D arranged point-symmetrically, and a support part 12 that supports the plurality of vibrating parts 10A to 10D so that they can vibrate, wherein the plurality of vibrating parts 10A to 10D have a first part 31 extending in a first direction P from a fixed part 33 fixed to the support part 12, and a second part 32 connected to the first part 31 at the tip 31b side in the first direction P and extending in a second direction Q different from the first direction P, and having a wider width at the tip 32b side in the second direction Q than at the base end 32a side connected to the first part 31.

Description

Technical Field

[0001] The present invention relates to a vibration detection device, a vital sensor, and a pipe sensor.

Background Art

[0002] As a vibration detection device for detecting vibration, a piezoelectric type vibration detection device that converts the displacement of a piezoelectric element due to vibration into an electric signal and detects it is known.

[0003] For example, in Patent Document 1 (Japanese Patent No. 5936154), a piezoelectric transducer including a plurality of cantilever beams that convert sound pressure into an electric signal has been proposed.

[0004] In such a configuration including a plurality of cantilever beams, when the cantilever beams are warped due to residual stress, there is a problem that the gap between the cantilever beams increases and the sensitivity of vibration detection decreases.

[0005] In response to such a problem, in Patent Document 1, a configuration is proposed in which the beam ends of a plurality of cantilever beams gather at a common point without contacting each other. By adopting such a configuration, it is said that a decrease in sensitivity due to an increase in the gap between the cantilever beams can be suppressed.

[0006] However, in the piezoelectric transducer described in Patent Document 1, there is room for improvement from the viewpoint of further improving sensitivity.

Summary of the Invention

Problems to be Solved by the Invention

[0007] Therefore, an object of the present invention is to achieve both suppression of a decrease in sensitivity due to an increase in the gap and further improvement in sensitivity.

Means for Solving the Problems

[0008] To solve the above problems, the vibration detection device according to the present invention comprises a plurality of vibrating parts arranged point-symmetrically and a support part that supports the plurality of vibrating parts so that they can vibrate, wherein the plurality of vibrating parts have a first part that extends in a first direction from a fixed part fixed to the support part and a second part that is connected to the first part at the tip end side in the first direction and extends in a second direction different from the first direction, and is wider at the tip end side in the second direction than at the base end side connected to the first part. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress the decrease in sensitivity associated with an increase in gap, and to further improve sensitivity. [Brief explanation of the drawing]

[0010] [Figure 1] This is a plan view of a vibration detection device according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view of the vibration detection device along the line A1-A1 in Figure 1. [Figure 3] This is a plan view showing an enlarged portion of a vibration detection device according to the first embodiment of the present invention. [Figure 4] This is a cross-sectional view showing the case where warping occurs in the section along line A1-A1 in Figure 1. [Figure 5] This is a plan view showing the detection electrode wiring structure of a vibration detection device according to a second embodiment of the present invention. [Figure 6] This is a schematic cross-sectional view showing the detection electrode wiring structure of a vibration detection device according to a second embodiment of the present invention. [Figure 7] This is a plan view showing the detection electrode wiring structure of a vibration detection device according to a third embodiment of the present invention. [Figure 8] This is a schematic cross-sectional view showing the detection electrode wiring structure of a vibration detection device according to a third embodiment of the present invention. [Figure 9] This is a plan view showing the detection electrode wiring structure of a vibration detection device according to the fourth embodiment of the present invention. [Figure 10]It is a cross-sectional view schematically showing a detection electrode wiring structure of a vibration detection device according to a fourth embodiment of the present invention. [Figure 11] It is a diagram for explaining the deflection angle of a cantilever beam. [Figure 12] It is a diagram showing an example of a model of a vibrating part. [Figure 13] It is a diagram showing another example of a model of a vibrating part. [Figure 14] It is a diagram showing a model with improved sensitivity of a vibrating part. [Figure 15] It is a diagram showing a model of a vibrating part for which simulation has been performed. [Figure 16] It is a diagram showing simulation results of deflection amounts when the same sound pressure is applied to each model in FIG. 15. [Figure 17] It is a diagram for explaining a model for which simulation of a resonance frequency has been performed. [Figure 18] It is a diagram showing simulation results of sensitivity when the same sound pressure is applied to each model in FIG. 17. [Figure 19] It is a diagram showing a comparison of the center of gravity positions between a model of a rectangular vibrating part and a model of a vibrating part whose width widens from the fixed end toward the tip direction. [Figure 20] It is a diagram for explaining a model for which simulation of a resonance frequency has been performed. [Figure 21] It is a diagram showing simulation results of a resonance frequency. [Figure 22] It is a plan view showing a first modification example of a vibrating part. [Figure 23] It is a plan view showing a second modification example of a vibrating part. [Figure 24] It is a diagram showing an example in which a vibration detection device according to the present invention is applied to a vital sensor. [Figure 25] It is a diagram showing an example in which a vibration detection device according to the present invention is applied to a pipe sensor. [Figure 26] It is a plan view of a piezoelectric MEMS microphone according to a comparative example. [Figure 27]It is a cross-sectional view showing a case where warping occurs in the cross-section along line A2 - A2 of FIG. 26.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the description of the drawings, the same reference numerals are assigned to the same elements, and duplicate descriptions are omitted.

[0012] <Types of MEMS Microphones> First, the types of MEMS microphones, which are an example of a vibration detection device, will be described.

[0013] A MEMS microphone is a device that receives external vibrations such as sound waves by a vibrating part and converts the displacement of the vibrating part into an electrical signal. For example, MEMS microphones for measuring audible sound are mainly used in acoustic devices, household electrical appliances, smartphones, etc. Also, as new applications of MEMS microphones, in addition to vital sensors that acquire vital data such as heartbeat and respiration, utilization in piping sensors that detect piping abnormalities, etc. has been proposed. Therefore, in recent years, the demand for MEMS microphones has been increasing.

[0014] Such MEMS microphones are mainly classified into a capacitive type and a piezoelectric type from the viewpoint of the vibration detection principle.

[0015] A capacitive MEMS microphone is a vibration detection device that detects the displacement amount of a movable electrode by detecting the electromotive force generated along with the change in the capacitance between parallel plate electrodes of a movable electrode and a fixed electrode that receive external vibrations, and converts the external vibrations into an electrical signal. The capacitive type has high sensitivity, low noise characteristics, a high signal-to-noise ratio, and excellent frequency characteristics, and thus is the most widely used type at present.

[0016] Furthermore, capacitive MEMS microphones benefit from reduced inter-electrode distance, which is advantageous for increasing device sensitivity. In recent years, the inter-electrode distance has been miniaturized to about 1 μm. On the other hand, applications such as vital signs sensors require high sensitivity in the low-frequency range of 100 Hz or less. To improve sensitivity in the low-frequency range, it is necessary to reduce the inter-electrode distance and increase the displacement of the vibrating part. However, reducing the inter-electrode distance and increasing the displacement of the vibrating part causes the vibrating part to come into contact with the opposing electrode, which presents a challenge in that the resonant frequency cannot be designed to be low (and thus the sensitivity on the low-frequency side cannot be improved). In addition, capacitive MEMS microphones require an input power supply to charge the parallel plate electrodes by applying a constant electric field during detection. The applied electric field generates an attractive force between the parallel plate electrodes, resulting in a disadvantage of a narrow dynamic range. Furthermore, there is also the challenge that the characteristics are greatly affected by the air resistance experienced by the movable electrode.

[0017] On the other hand, piezoelectric MEMS microphones are vibration detection devices that detect external vibrations by converting displacement caused by external vibrations into electrical signals through the piezoelectric effect. Piezoelectric MEMS microphones allow for detection with a simple structure, resulting in a simple device fabrication process and suitability for miniaturization. Furthermore, piezoelectric MEMS microphones do not require an input power supply, which simplifies the passive circuitry. In addition, piezoelectric MEMS microphones have characteristics such as a wider dynamic range compared to capacitive MEMS microphones. However, it has been pointed out that piezoelectric MEMS microphones have relatively lower sensitivity, noise characteristics, and signal-to-noise ratio characteristics compared to capacitive MEMS microphones. To improve the signal-to-noise ratio, it is necessary to improve both sensitivity and noise characteristics. Conventionally, MEMS microphones have been proposed that suppress sensitivity reduction due to residual stress in the piezoelectric film by using a cantilever structure for the piezoelectric film.

[0018] <Challenges of reduced sensitivity in piezoelectric MEMS microphones> Here, we will explain the issue of reduced sensitivity in piezoelectric MEMS microphones, using a comparative example different from the present invention as a reference. "Sensitivity" refers to the degree to which external vibrations can be detected; high sensitivity allows for the detection of weaker external vibrations, such as fainter sounds. Conversely, low sensitivity makes it difficult to detect external vibrations.

[0019] Figure 26 is a plan view of a piezoelectric MEMS microphone according to a comparative example. In Figure 26, the X, Y, and Z directions are arbitrarily defined as the three-dimensional coordinate axes of the microphone according to the comparative example.

[0020] As shown in Figure 26, the piezoelectric MEMS microphone 100 according to the comparative example comprises a plurality of vibrating parts 110A to 110D that vibrate when subjected to external vibrations such as sound waves, and a frame-shaped support part 112 that supports the plurality of vibrating parts 110A to 110D so that they can vibrate. Each vibrating part 110A to 110D has a piezoelectric film sandwiched between two electrodes (a lower electrode and an upper electrode). When each vibrating part 110A to 110D vibrates due to external vibrations, the piezoelectric film deforms, generating a potential difference between one electrode (upper electrode) and the other electrode (lower electrode). By detecting the electrical signal caused by this potential difference, vibration can be detected.

[0021] Furthermore, in the comparative example, in order to improve sensitivity, each vibrating section 110A to 110D is cantilevered by a support section 112. To explain using one vibrating section 110A as an example, in this case, of the four sides 111a to 111d that make up the outer shell of the vibrating section 110A, one side 111a is fixed to the support section 112, and the other sides 111b, 111c, and 111d are free ends. In this way, by having each vibrating section 110A to 110D in a cantilevered beam structure, it is possible to suppress the decrease in sensitivity due to residual stress in the piezoelectric film.

[0022] However, in vibration detection devices with such cantilever beam structures, there is a problem in that if warping occurs in the vibrating part due to residual stress during molding, the gap between adjacent vibrating parts increases, reducing sensitivity. For example, as shown in Figure 27, which shows the cross section along line A2-A2 in Figure 26, if warping occurs in the vibrating part 110A as shown by the dashed line in the figure, the tip of the vibrating part 110A is displaced upward, so the gap between adjacent vibrating parts 110A and 110B increases from G to G'. As a result, the effect of air leakage from between the vibrating parts 110A and 110B becomes greater, making it more difficult for the vibrating parts 110A and 110B to vibrate, and reducing sensitivity. In particular, at locations where the free ends and fixed ends of adjacent vibrating parts 110A to 110D are close together (locations indicated by the symbol B in Figure 26), the difference in displacement between the free end and the fixed end becomes large, and the increase in the gap between the vibrating parts tends to be more pronounced.

[0023] Therefore, the present invention aims to suppress the decrease in sensitivity that occurs with increasing gaps between vibrating parts. Furthermore, in order to realize a more sensitive vibration detection device, the present invention aims to further improve sensitivity in addition to suppressing the decrease in sensitivity that occurs with increasing gaps. The present invention will be described below with reference to embodiments of the present invention.

[0024] <Configuration of the first embodiment of the present invention> First, the basic structure of the vibration detection device according to the first embodiment of the present invention will be described based on Figures 1 and 2. Figure 1 is a plan view of the vibration detection device 1 according to the first embodiment of the present invention, and Figure 2 is a cross-sectional view of the vibration detection device 1 along the line A1-A1 in Figure 1.

[0025] In Figures 1 and 2, the X, Y, and Z directions are conveniently defined as the directions of the three-dimensional coordinate axes of the vibration detection device 1 according to the first embodiment of the present invention. In this case, the X direction indicates the horizontal direction when the vibration detection device 1 is viewed from above, as shown in Figure 1. The Y direction indicates the vertical direction perpendicular to the X direction (horizontal direction) when the vibration detection device 1 is viewed from above, and the Z direction indicates the direction perpendicular to both the X and Y directions when the vibration detection device 1 is viewed from above (for example, the vertically upward direction when the vibration detection device 1 is placed on a plane). In addition, the X, Y, and Z directions indicate the same directions in other drawings besides Figures 1 and 2.

[0026] As shown in Figure 1, the vibration detection device 1 according to the first embodiment of the present invention comprises a plurality of vibrating parts 10A to 10D and a support part 12 that supports the plurality of vibrating parts 10A to 10D so that they can vibrate.

[0027] The multiple vibrating parts 10A to 10D are parts that vibrate in response to external vibrations such as sound waves. In this case, four of each vibrating part 10A to 10D are provided and arranged within the frame-shaped support part 12 to form a square as a whole.

[0028] The support section 12 is a square frame of a certain width that surrounds the entire perimeter of the four vibrating sections 10A to 10D. One vibrating section 10A to 10D is fixed to each of the four inner wall surfaces constituting the support section 12, and each vibrating section 10A to 10D is arranged point-symmetrically with respect to the center of the support section 12. Furthermore, each vibrating section 10A to 10D is positioned with a predetermined gap between adjacent vibrating sections so that they do not come into contact with each other.

[0029] Here, using one vibrating section 10A shown in Figure 2 as an example, the cross-sectional configuration of each vibrating section 10A to 10D will be explained. Each vibrating section 10A to 10D is composed of a layered structure including a strain detection section 14 and a vibrating section substrate 16.

[0030] The strain detection unit 14 has a piezoelectric film formed from a piezoelectric material. The piezoelectric film material is selected from thin-film-compatible materials such as PZT (lead zirconate titanate), KNN (potassium sodium niobate), AlN (aluminum nitride), and AlScN (scandium aluminum nitride). The piezoelectric film is sandwiched between two electrodes (a lower electrode and an upper electrode). When the piezoelectric film deforms due to external vibration, a potential difference is generated between the electrodes. By detecting the electrical signal caused by this potential difference, the strain generated by the vibration can be detected. The electrical signal generated between the two electrodes is configured to be sent to an external device such as a computing unit via wiring connected to each electrode.

[0031] The vibrating part substrate 16 is a substrate formed from silicon or the like. Because silicon substrates have high crystallinity, forming the vibrating part substrate 16 from a silicon substrate allows each vibrating part 10A to 10D to vibrate flexibly without fracture. The thickness of the vibrating part substrate 16 should be such that each vibrating part 10A to 10D vibrates appropriately, preferably a few microns to several tens of microns. The vibrating part substrate 16 can be formed by semiconductor processes such as MEMS (Micro Electro Mechanical Systems).

[0032] Furthermore, similar to the vibrating substrate 16, the support portion 12 can also be formed from silicon or the like. The support portion 12 may be a single-layer structure formed from a single material, or it may be composed of multiple layers such as an active silicon layer and a silicon oxide layer. Also, if the support portion 12 consists of multiple layers, any of the layers constituting the support portion 12 may be the same silicon layer as the vibrating substrate 16.

[0033] The thickness of the support portion 12 is preferably about 200 to 600 microns, which is easy to handle as a wafer in semiconductor processes. Furthermore, since the support portion 12 functions as a frame member forming the outer casing of the vibration detection device 1, it is preferable that it has mechanical strength and strength suitable for the bonding process in semiconductor processes.

[0034] Next, the configuration of the characteristic parts of the vibration detection device 1 according to the first embodiment of the present invention will be described.

[0035] As shown in Figure 1, each vibrating part 10A to 10D mainly consists of a first part 31 arranged longitudinally along the inner wall surface of the support part 12, a second part 32 arranged closer to the center of the support part 12 than the first part 31, a fixing part 33 fixed to the support part 12, and a connecting part 34 connecting the first part 31 and the second part 32.

[0036] Here, since each of the vibration parts 10A to 10D according to the first embodiment of the present invention has the same shape and structure, the shape and structure of each vibration part 10A to 10D will be described in detail, using one vibration part 10A as an example, with reference to Figure 3. Figure 3 is a plan view showing an enlarged portion of the vibration detection device 1 according to the first embodiment of the present invention.

[0037] In Figure 3, for clarity, the first part 31, the second part 32, the fixed part 33, and the connecting part 34 of the vibrating part 10A are shown separated by dashed lines. However, these divisions are for convenience only and do not limit the respective regions and shapes of the first part 31, the second part 32, the fixed part 33, and the connecting part 34.

[0038] As shown in Figure 3, the first portion 31 is connected to the fixing portion 33 at its longitudinal end, the base end 31a (right end in Figure 3). Thus, the first portion 31 is fixed to the support portion 12 via the fixing portion 33. On the other hand, at the tip end 31b (left end in Figure 3), opposite to the base end 31a of the first portion 31, the base end 32a of the second portion 32 is connected via the connecting portion 34.

[0039] The first part 31 is fixed to the support part 12 only at the connection point with the fixed part 33. In other words, the first part 31 is not fixed to the support part 12 directly or indirectly at any point other than the fixed part 33. Similarly, the second part 32 and the connecting part 34 are not fixed to the support part 12 directly or indirectly except at the point where they are indirectly fixed to the support part 12 via the first part 31 (fixing part 33). For this reason, the first part 31, the second part 32, and the connecting part 34 are cantilevered and vibrate with the fixed part 33 as the fulcrum.

[0040] Thus, in the first embodiment of the present invention, the first portion 31, the second portion 32, and the connecting portion 34 are cantilevered with the fixed portion 33 as a fulcrum, so the base end 32a of the second portion 32 is a free end. Therefore, if the vibrating portion 10A warps, the base end 32a of the second portion 32 can be displaced due to the warping. Furthermore, since the base end 32a of the second portion 32 is located away from the fixed end (fixed portion 33) via the first portion 31 extending from the fixed portion 33, it is hardly affected by the constraint of the fixed end when the vibrating portion 10A warps. Therefore, when warping occurs, the base end 32a of the second portion 32 can be displaced in the same way as the tip 32b of the second portion 32.

[0041] For example, using the A1-A1 cross-section in Figure 1 as an example, if the vibrating part 10A warps, as shown by the dashed line in Figure 4, the portion K on the base end 32a side and the portion J on the tip end 32b side of the second portion 32 are displaced upward as a result of this warping. At this time, the portion K on the base end 32a side and the portion J on the tip end 32b side are displaced by the same amount. Furthermore, this type of displacement due to warping is not limited to the vibrating part 10A shown in Figure 4, but occurs similarly in the other vibrating parts 10B, 10C, and 10D. Therefore, in Figure 4, among the adjacent vibrating parts 10A and 10B, the portion J on the tip end 32b side of the second portion 32 of one vibrating part 10A and the portion K on the base end 32a side of the second portion 32 of the other vibrating part 10B are displaced by the same amount.

[0042] Thus, in the first embodiment of the present invention, the portion J on the tip 32b side and the portion K on the base 32a side of the second portion 32, which are opposite to each other, are both displaced in the same direction and to the same extent as with warping. Therefore, compared to the comparative example where the opposing portions are a free end and a fixed end (see Figure 27), the increase in the gap G due to warping can be suppressed. That is, in the comparative example, since the opposing portions are a free end and a fixed end, the difference in displacement due to warping tends to be large and the gap G tends to increase (see Figure 27). However, in the first embodiment of the present invention, as shown by the dashed line in Figure 4, the portion J on the tip 32b side and the portion K on the base 32a side of the second portion 32, which are opposite to each other, are displaced to the same extent. Therefore, the difference in displacement can be reduced and the increase in the gap G can be suppressed. Therefore, in Figure 1, at the points where the tip 32b portion J and the base 32a portion K of the second portion 32 of adjacent vibrating parts 10A to 10D face each other, that is, at each point indicated by the symbol B in Figure 1, the increase in the gap G due to warping can be suppressed in the same way. Furthermore, at other points where the second portions 32 face each other (for example, near the center of the support portion 12 where the tips 32b of the four second portions 32 meet in Figure 1), the free ends of the second portions 32 are displaced in the same direction and to the same extent, so the increase in the gap G is suppressed.

[0043] As described above, in the first embodiment of the present invention, even if warping occurs in each vibrating part 10A to 10D, the increase in the gap G due to warping can be effectively suppressed because the opposing parts of the second part 32 are displaced in the same direction by the same amount. Thus, in the first embodiment of the present invention, the decrease in sensitivity due to the increase in the gap G between each vibrating part 10A to 10D can be effectively suppressed. Note that the amount of displacement of the opposing parts of the second part 32 when warping occurs does not necessarily have to be the same. Even if the amount of displacement of the opposing parts of the second part 32 is different, the difference in displacement can be reduced compared to the amount of displacement between the free end and the fixed end as in the comparative example, so the increase in the gap G can be suppressed. Furthermore, although Figure 4 describes an example in which the displacement of the base end 32a and tip end 32b of the second part 32 due to warping occurs upward, even if the displacement occurs in the opposite direction (downward) to the example in Figure 4, it is possible to suppress the increase in the gap G by a similar mechanism.

[0044] Next, we will explain how the sensitivity can be improved in the first embodiment of the present invention.

[0045] As described above, in the first embodiment of the present invention, the second portion 32 is connected to the tip 31b side of the first portion 31 via the connecting portion 34, so that each end of the second portion 32, including the base end 32a, is a free end. For this reason, the second portion 32 is configured to bend more easily overall during vibration compared to when it is directly fixed to the support portion 12. Moreover, because the second portion 32 is connected to the tip 31b side of the first portion 31 via the connecting portion 34, a longer distance can be secured from the fixing portion 33 (fixed end side) through the first portion 31 to the tip 32b of the second portion 32. For this reason, a larger amount of deflection can be secured, especially at the tip 32b side of the second portion 32. Furthermore, in the first embodiment of the invention, as shown in Figure 3, the second portion 32 is configured so that its width increases from the base end 31a side to the tip 32b side, which increases the flexibility of the second portion 32.

[0046] Thus, in the first embodiment of the present invention, sensitivity is improved by making the second portion 32 more flexible. As a result, sensitivity in the low-frequency range can be improved, particularly in the first embodiment of the present invention. The "low-frequency range" referred to here is the frequency range near the human audible range (for example, 20 Hz to 20 kHz, which is the general audible range), and within that, for example, the frequency range of 100 Hz or less. Therefore, according to the first embodiment of the present invention, it is possible to provide a vibration detection device that is particularly excellent in detection sensitivity in the frequency range of 100 Hz or less and is highly reliable.

[0047] Furthermore, the "width" of the second portion 32 as described above refers to the width in a direction that intersects with the extension direction of the second portion 32 from its base end 32a to its tip end 32b (direction of arrow Q in Figure 3), when the second portion 32 is viewed from a direction perpendicular to the virtual plane containing each vibrating portion 10A to 10D (a plan view as shown in Figure 3). For example, it is the width in a direction perpendicular to the extension direction of the second portion 32 (direction Y in Figure 3). However, the "width" of the second portion 32 is not necessarily limited to the width in a direction perpendicular to the extension direction of the second portion 32 (direction Y in Figure 3), but may be the width in any direction that intersects with the extension direction of the second portion 32. Therefore, the "width" of the second portion 32 may be the width in a direction oblique to the extension direction of the second portion 32.

[0048] Furthermore, the "width" of the second portion 32 does not have to be continuously larger over the entire area from the base end 32a to the tip end 32b of the second portion 32. For example, if the width of the second portion 32 is the width in the Y direction in Figure 3, in the first embodiment of the present invention, the width of the second portion 32 decreases along the way from its base end 32a to its tip end 32b, but the "width" of the second portion 32 may decrease or increase intermittently along the way. Also, the "width" of the second portion 32 only needs to be wider at any point on the tip end 32b side than at any point on the base end 32a side, with the intermediate position in the extension direction of the second portion 32 as the reference (boundary).

[0049] In order to ensure good flexibility of the second portion 32, it is preferable to increase the distance from the fixed portion 33 (fixed end side) through the first portion 31 to the tip 32b of the second portion 32. For this reason, it is preferable that the first portion 31 has a certain length or more. Specifically, in Figure 3, if L1 is the length from the end of the connection portion (connection portion 34) of the first portion 31 with the second portion 32 on the fixed portion 33 side to the part furthest toward the fixed portion 33, and L2 is the length from the end of the connection portion (connection portion 34) of the second portion 32 with the first portion 31 on the fixed portion 33 side to the part furthest toward the tip 32b, then it is preferable that the length L1 is 0.25 times or more and 0.75 times or less of the length L2. In this way, by making the length L1 of the first part 31 0.25 times or more and 0.75 times or less of the length L2 of the second part 32, the length L1 of the first part 31 can be set to a certain length or more, and the flexibility of the second part 32 can be well ensured, thereby effectively improving sensitivity.

[0050] However, when the second portion 32 vibrates, if the tip 32b of the second portion 32 comes into contact with the base end 31a (fixed end) of the first portion 31, the displacement of the tip 32b of the second portion 32 is constrained by the contact with the first portion 31. As a result, the tip 32b of the second portion 32 becomes less flexible, which may reduce sensitivity. Therefore, as shown in Figure 3, it is preferable that the tip 32b of the second portion 32 is provided with a predetermined gap so that it does not come into contact with the base end 31a of the first portion 31. By providing a gap between the tip 32b of the second portion 32 and the base end 31a of the first portion 31 in this way, a decrease in sensitivity due to contact between them can be avoided, and good sensitivity can be maintained.

[0051] Furthermore, the length of the first portion 31 is preferably above a certain length, not only to improve sensitivity but also to suppress the increase in the gap G due to warping. If the first portion 31 is long, the first portion 31 itself becomes more flexible, so the base end 32a of the second portion 32, which is connected to the tip 31b side of the first portion 31, becomes more easily displaced, and the increase in the gap G due to warping can be suppressed more reliably. Accordingly, by making the length L1 of the first portion 31 0.25 times or more and 0.75 times or less of the length L2 of the second portion 32, the amount of displacement of the base end 32a side of the second portion 32 can be made equivalent to the amount of displacement of the tip 32b side, and the decrease in sensitivity due to the increase in the gap G can be suppressed more reliably.

[0052] Furthermore, in the first embodiment of the present invention, the first direction P, which is the extension direction of the first portion 31, and the second direction Q, which is the extension direction of the second portion 32, are opposite to each other, so that the first portion 31 and the second portion 32 can be efficiently arranged within the frame of the support portion 12. Accordingly, according to the first embodiment of the present invention, the vibration detection device can be miniaturized.

[0053] Furthermore, in the first embodiment of the present invention, as shown in Figure 3, the first portion 31 extends linearly from its base end 31a to its tip end 31b, thus saving space for the first portion 31. That is, since the first portion 31 extends (towards the first direction P) without bending in a direction intersecting the extension direction (first direction P) between its base end 31a and tip end 31b, the increase in size in the direction intersecting the extension direction (first direction P) can be suppressed compared to the case where the first portion 31 bends in a direction intersecting the extension direction (first direction P), thus enabling miniaturization. Accordingly, the first embodiment of the present invention makes it possible to provide a compact and highly sensitive vibration detection device.

[0054] [Other embodiments] Next, other embodiments of the present invention will be described. In the following description, we will mainly describe parts that differ from the first embodiment of the present invention, and descriptions of the same parts will be omitted as appropriate.

[0055] <Configuration of the second embodiment of the present invention>

[0056] First, a vibration detection device according to the second embodiment of the present invention will be described based on Figures 5 and 6. Figure 5 is a plan view showing the detection electrode wiring structure of the vibration detection device according to the second embodiment of the present invention, and Figure 6 is a schematic cross-sectional view showing the detection electrode wiring structure of the vibration detection device according to the second embodiment of the present invention.

[0057] As shown in Figure 5, in the second embodiment of the present invention, the support portion 12 is provided with two electrode portions 41 and 42. Furthermore, the strain detection portion 14 of the vibration portion 10A is electrically connected to the two electrode portions 41 and 42 via wiring 26 and 27. Specifically, as shown in Figure 6, the strain detection portion 14 is provided with two electrodes 5 and 6 (upper electrode and lower electrode) that sandwich the piezoelectric film 4, and these electrodes 5 and 6 are individually connected to the respective electrode portions 41 and 42 of the support portion 12 via separate wiring 26 and 27. In addition, the respective electrode portions 41 and 42 of the support portion 12 are electrically connected to a computing device or the like. As a result, when an electrical signal is generated at each electrode 5 and 6 due to the deformation of the piezoelectric film 4, the electrical signal is sent to the computing device or the like via the respective wiring 26 and 27 and the respective electrode portions 41 and 42.

[0058] In this second embodiment of the present invention, strain detection units 14 are provided in both the first portion 31 and the second portion 32. However, the electrical signals generated at each electrode 5,6 of the first portion 31 and the electrical signals generated at each electrode 5,6 of the second portion 32 are in opposite phases. Therefore, if electrical signals that are in opposite phases are transmitted as they are, the electrical signals will cancel each other out, resulting in a decrease in sensitivity.

[0059] Therefore, in the second embodiment of the present invention, only the electrodes 5 and 6 in the second portion 32 are connected to the two electrode portions 41 and 42, while the electrodes 5 and 6 in the first portion 31 are not connected to the electrode portions 41 and 42 of the support portion 12, nor to the electrodes 5 and 6 of the second portion 32. This avoids a decrease in sensitivity due to the cancellation of electrical signals that are in opposite phases, thus enabling good sensitivity to be obtained.

[0060] <Configuration of the third embodiment of the present invention>

[0061] Next, a vibration detection device according to the third embodiment of the present invention will be described based on Figures 7 and 8. Figure 7 is a plan view showing the detection electrode wiring structure of the vibration detection device according to the third embodiment of the present invention, and Figure 8 is a schematic cross-sectional view showing the detection electrode wiring structure of the vibration detection device according to the third embodiment of the present invention.

[0062] As shown in Figures 7 and 8, in the third embodiment of the present invention, contrary to the second embodiment described above, only the electrodes 5 and 6 in the first portion 31 are connected to the two electrode portions 41 and 42. On the other hand, the electrodes 5 and 6 in the second portion 32 are not connected to the electrode portions 41 and 42 of the support portion 12, nor to the electrodes 5 and 6 in the first portion 31.

[0063] Thus, in the third embodiment of the present invention, since only the electrodes 5 and 6 in the first portion 31 are connected to the two electrode portions 41 and 42, a decrease in sensitivity due to the cancellation of electrical signals in opposite phases can be avoided. Therefore, good sensitivity can be obtained in this case as well.

[0064] <Configuration of the 4th embodiment of the present invention>

[0065] Next, a vibration detection device according to the fourth embodiment of the present invention will be described with reference to Figures 9 and 10. Figure 9 is a plan view showing the detection electrode wiring structure of the vibration detection device according to the fourth embodiment of the present invention, and Figure 10 is a schematic cross-sectional view showing the detection electrode wiring structure of the vibration detection device according to the fourth embodiment of the present invention.

[0066] As shown in Figures 9 and 10, in the fourth embodiment of the present invention, each electrode 5, 6 in the first portion 31 and each electrode 5, 6 in the second portion 32 are individually connected via separate wirings 26, 27. However, in this case, the electrode 6 (lower electrode) provided on one surface of the piezoelectric film 4 in the first portion 31 (the lower surface in Figure 10) and the electrode 5 (upper electrode) provided on the surface of the piezoelectric film 4 in the second portion 32 facing the opposite side (the upper surface in Figure 10) are connected via wiring 26. Furthermore, the electrode 5 (upper electrode) provided on the other surface of the piezoelectric film 4 in the first portion 31 (the upper surface in Figure 10) is connected to the electrode 6 (lower electrode) provided on the surface of the piezoelectric film 4 in the second portion 32 facing the opposite side (the lower surface in Figure 10) via another wiring 27. In other words, in the fifth embodiment of the present invention, electrodes 5 and 6 provided on opposite sides of the piezoelectric film 4 of the first portion 31 and the second portion 32 are electrically connected to each other. Furthermore, only the electrodes 5 and 6 in the first portion 31 are individually connected to the two electrode portions 41 and 42 via wiring 28 and 29.

[0067] Thus, in the fifth embodiment of the present invention, the electrodes 5 and 6 provided on opposite sides of the piezoelectric film 4 of the first portion 31 and the second portion 32 are electrically connected, so that the out-of-phase electrical signals generated in the first portion 31 and the second portion 32 can be added together and output. For this reason, in the fifth embodiment of the present invention, compared to the case where vibration detection is performed using only the electrical signal from either the first portion 31 or the second portion 32, the sensitivity can be improved, and a more sensitive vibration detection device can be provided.

[0068] The above description of the detection electrode wiring structure of a vibration detection device according to another embodiment of the present invention was based on the structure of one vibration section 10A shown in Figures 5 to 10 as an example. However, the same wiring structure can be adopted for the other vibration sections 10B, 10C, and 10D. Furthermore, the detection electrode wiring structures in each vibration section 10A to 10D are not necessarily all the same; they may be different.

[0069] <Relationship between the shape of the vibrating part and sensitivity> Next, we will explain the relationship between the shape of the vibrating part and its sensitivity.

[0070] Figure 11 is a model of a vibrating section 10, in which one end (fixed end) 18 is fixed to a support section 12 and the other end (tip) 19 is configured as a free end. It is a diagram used to explain the deflection angle of a cantilever beam. The dashed line shown in Figure 11 represents the vibrating section 10 deformed by the moment M0 generated by the sound pressure P0. The angle shown by this dashed line is called the deflection angle θ.

[0071] Figure 12 shows an example of a model of the vibrating part 10. The charge generated in the strain detection unit 14 when an external vibration such as sound is incident is proportional to the amount of strain in the strain detection unit 14. The amount of strain in the strain detection unit 14, dz / dx (= deflection angle θ), is expressed by the following equation using the distance x in the direction from the tip 19 of the vibrating part 10 toward the fixed end 18 (-X direction) in Figure 12. Note that the tip 19 refers to the point on the outer circumference of the vibrating part 10 that is furthest from the fixed end 18 in the direction perpendicular to the line segment direction of the fixed end 18 (X direction).

[0072]

number

[0073] Here, dz and dx are infinitesimal changes on the X and Z axes, respectively, as shown in Figure 12. M(x) is the bending moment at position x, W(x) is the width in the line segment direction of the fixed end of the vibrating part 10 at position x, E is Young's modulus, I(x) is the second moment of area at position x, and t is the thickness of the vibrating part 10 (width in the Z-axis direction). It is assumed that the thickness t of the vibrating part 10 is constant.

[0074] Next, we will explain how to calculate the bending moment M(x) at position x when sound pressure P0 is applied to the vibrating part 10. The magnitude of the load acting on a small length dξ is W(ξ)P0dξ. From this, the bending moment at position ξ is expressed as W(ξ)ξP0dξ, where ξ represents any position in the interval from the tip 19 to a distance x. The bending moment M(x) at distance x is obtained by integrating W(ξ)ξP0dξ from the tip 19 (x=0) to distance x, and can be expressed as follows. Note that the direction in which sound pressure P0 is applied is parallel to the Z axis, and in the model, it is assumed that the pressure is the same in all regions.

[0075]

number

[0076] The sum of the strain amounts dz / dx of the strain detection unit 14 from the tip 19 (x=0) to the fixed end 18 (x=L) of the cantilever beam (vibrating part 10) can be expressed by the following formula.

[0077]

number

[0078] L is the length from the fixed end 18 to the tip 19 (reference point) of the vibrating part 10 that is furthest from it in the direction perpendicular to the line segment direction of the fixed end 18 (X-axis direction).

[0079] Figure 13 shows another example of the model of the vibrating part 10. In this example, the vibrating part 10 is rectangular. The width of the vibrating part 10 is constant W0. The length L of the vibrating part 10 is the same as in the model in Figure 12. We assume that the area of ​​the model in Figure 12 and the model in Figure 13 are the same. The sum of the strain amount dz / dx of the strain detection unit 14 in Figure 13 from the tip 19 (x=0) to the fixed end 18 (x=L) of the cantilever beam (vibrating part 10) can be expressed by the following formula.

[0080]

number

[0081] In the example shown in Figure 13, a larger strain amount dz / dx results in a larger deflection angle θ for the same pressure (sound pressure P0). This improves the sensitivity of the vibration detection device. In other words, the sensitivity can be improved by fulfilling the following equation.

[0082]

number

[0083] By removing Young's modulus E, thickness t, and sound pressure P0 from both sides of the above equation, we can derive the following equation (Equation 1).

[0084]

number

[0085] This condition can be met by designing the vibrating part 10 so that its width increases from the fixed end 18 towards the tip 19 (X direction), thereby improving sensitivity. Another method for evaluating the shape of the actually created vibrating part 10 is to use microscope images. By detecting the image, it is possible to quantify the area, which is the integral value from the positional information, through image processing. For example, by using a Keyence digital microscope (VHX-8000), it is possible to quantitatively calculate the area of ​​an arbitrary shape, the moment calculated from the distance, etc. It is also possible to calculate the center of gravity, etc., by assuming mass and density.

[0086] Figure 14 shows a model in which the sensitivity of the vibrating part 10 has been improved. A feature of the model in Figure 14 is that when the area of ​​the vibrating part 10 is divided in half by a straight line 58 that is parallel to the direction of the fixed end 18 (Y direction) and passes through the midpoint 54 of the shortest line segment 52 that connects the outer circumference of the vibrating part 10 and the fixed end 18, the area on the fixed end 18 side is designated as the first area 62, and the area on the tip side (opposite the fixed end 18 side) is designated as the second area 64. At this time, a characteristic feature is that the area 64 on the tip side of the vibrating part 10 divided by the straight line 58 is larger than the area 62 on the fixed end 18 side.

[0087] Furthermore, the shape features that further enhance the sensitivity of the vibrating part 10 will be explained from another perspective. The width features of the vibrating part 10 are shown.

[0088] When the midpoint 54 is taken of the shortest line segment 52 in the direction perpendicular to the line segment direction of the fixed end 18 (X direction) connecting the fixed end 18 and the outer circumference of the vibrating part 10, the width of the vibrating part 10 in the direction parallel to the line segment direction of the fixed end 18 (Y direction) is characterized by being maximum at a position further from the fixed end 18 than the midpoint 54 in the direction perpendicular to the line segment direction of the fixed end 18 (X direction). In other words, the position of the maximum width 56 of the vibrating part 10 in the direction parallel to the line segment direction of the fixed end 18 (Y direction) is further from the fixed end 18 than the midpoint 54. This makes it possible to improve the sensitivity of the vibration detection device 1.

[0089] Next, we will describe the results of verifying the above effects through simulation. Figure 15 shows the models used in the simulation. In Figure 15, (a) is a model of a triangular vibrating part 10, (b) is a model of a rectangular vibrating part 10, and (c) is a model of a trapezoidal vibrating part 10 whose width widens from the fixed end 18 toward the tip 19 (X direction). The area of ​​each model in Figure 15 is the same.

[0090] Figure 16 shows the simulation results of the amount of deflection when the same sound pressure is applied to each model in Figure 15. The vertical axis shows the amount of deflection, and the horizontal axis shows the position in the X direction. It can be seen that the model in Figure 15(c) has a larger amount of deflection and higher sensitivity compared to the models in Figure 15(a) and Figure 15(b).

[0091] To improve the sensitivity of the vibration detection device, it is necessary to increase the deflection angle at each point of the vibrating part 10 when uniform pressure is applied to the vibrating part 10. Therefore, the area from a certain point to the tip of the vibrating part 10 should be increased, and by shaping the vibrating part 10 so that its width continuously widens from the fixed end to the tip, a highly sensitive vibration detection device can be realized. Accordingly, in the vibration detection device according to the present invention, by shaping the vibrating part 10 so that its width continuously widens from the fixed end to the tip, sensitivity in the low-frequency band can be improved.

[0092] Figure 17 illustrates the model used for the resonance frequency simulation. In Figure 17, (a) is a triangular vibrating part 10 model, (b) is a rectangular vibrating part 10 model, (c) is a trapezoidal vibrating part 10 model whose width widens from the fixed end 18 towards the tip 19 (X direction), and (d) is a trapezoidal model of (c) with the length L from the tip to the fixed end doubled. Note that the area of ​​each model in Figure 17 is the same.

[0093] Figure 18 shows the simulation results of the sensitivity when the same sound pressure is applied to each model in Figure 17. Here, the relative sensitivity is shown with the sensitivity of the model in Figure 17(a) set as "1" (reference). From these results, it can be seen that the sensitivity of the model in Figure 17(c) is improved compared to the models in Figure 17(a) and Figure 17(b). Furthermore, it can be seen that the sensitivity of the model in Figure 17(d), in which the length from the tip to the fixed end is doubled compared to the model in Figure 17(c), is even improved. Therefore, it can be said that the sensitivity will be further improved if the vibrating part 10 is made longer in the direction perpendicular to the line segment direction of the fixed end (X direction).

[0094] Next, the resonant frequency band of the vibrating part will be explained. When the resonant frequency of the vibrating part is around 100 to several kHz, it is in a low frequency range, unlike the typical range of several tens of kHz, making it suitable for measurements such as heart rate and hydrophones used in pipe inspections. One way to realize a vibrating part suitable for such low-frequency measurements is to reduce the frequency by lengthening the vibrating part 10, as described above. However, lengthening the vibrating part 10 presents challenges such as increasing the size of the vibration detection device and reducing the mechanical strength and reliability of the vibrating part 10. Therefore, methods for reducing the frequency without lengthening the vibrating part 10 are being explored.

[0095] Figure 19 shows a comparison of the center of gravity positions of a rectangular vibrating section 10 model and a vibrating section 10 model in which the width widens from the fixed end 18 toward the tip 19 (X direction). In the rectangular vibrating section 10 model, the center of gravity is located at point 22 in the center of L / 2. In contrast, in the widening vibrating section 10 model, the tip 19 side of the vibrating section is wider than the fixed end 18, so the center of gravity is located at point 24 on the tip 19 side of the center. Note that the mass per unit volume of each vibrating section 10 is constant.

[0096] Figure 20 illustrates a model used to simulate the resonant frequency. In Figure 20, W1 is the length of the fixed end 18 of the vibrating part 10 in the line segment direction (Y direction), and W2 is the length of the tip 19 in the line segment direction (Y direction). The length of the tip 19 is taken at the position furthest from the fixed end 18 in the direction perpendicular to the line segment direction of the fixed end 18 (X direction), where W2 is taken. Assuming that the area of ​​the vibrating part 10 (W1+W2)L / 2 and the length L of the vibrating part 10 are constant, the resonant frequency was calculated when W2 / W1 was changed. However, it was assumed that the end shapes other than the fixed end 18 and tip 19 were connected by straight lines, without any concave or bulging shapes. Also, the thickness and density of the vibrating part 10 were assumed to be constant.

[0097] Figure 21 shows the simulation results. In Figure 21, the vertical axis represents the resonant frequency, and the horizontal axis represents the value of W2 / W1. When W2 / W1 = 1, it represents a rectangular vibrating part 10 model, and it shows that the shape of the vibrating part 10 is such that the width of the tip widens as the value of W2 / W1 increases. According to these simulation results, as W2 / W1 increases, the resonant frequency decreases, so it can be seen that the resonant frequency can be reduced when the width of the tip of the vibrating part 10 is wider compared to when the vibrating part 10 is rectangular. Furthermore, the resonant frequency is reduced when the width of the tip of the vibrating part 10 increases. This can be rephrased in terms of the position of the center of gravity mentioned earlier, and it can be said that the resonant frequency can be reduced when the distance between the center of gravity of the vibrating part 10 and the fixed end is L / 2 or greater.

[0098] Therefore, in the vibration detection device according to the present invention, if the relationship W2 / W1 > 1 is satisfied when the length of the fixed end 18 of the vibrating part 10 in the line segment direction (Y direction) is W1 and the length of the tip in the line segment direction (Y direction) is W2, then the mass increases as you approach the tip of the vibrating part 10, which lowers the resonant frequency and improves the sensitivity in the low-frequency band.

[0099] Furthermore, the relationship between the shape (length and width) of the vibrating part and sensitivity described above is the same not only for the model of the vibrating part 10 that is cantilevered with a fixed end 18 as the fulcrum, as shown in Figure 11, but also for models having a second part 32 that is cantilevered with a free end (base end 32a) as the fulcrum, as in each embodiment of the present invention. Therefore, as in each embodiment of the present invention, by extending the second part 32 from the tip 31b of the first part 31 to lengthen the entire vibrating part, and by widening the second part 32 toward its tip 32b, it is possible to effectively improve sensitivity in the low-frequency band.

[0100] [Differential examples of the vibrating part] Next, a modified example of the vibrating part according to the present invention will be described.

[0101] <First variation> Figure 22 is a plan view showing a first modified example of the vibrating section.

[0102] The first modified example shown in Figure 22 is characterized by the fact that the opposing sides (free ends) of each vibrating section 10A to 10D are curved. By making the sides of each vibrating section 10A to 10D curved, the degree of design freedom is increased. Furthermore, by utilizing this degree of design freedom, the pressure that can be received by the tips of each vibrating section 10A to 10D can be further increased, thereby generating a larger deflection angle and improving the sensitivity of the vibration detection device.

[0103] <Second variation> Figure 23 is a plan view showing a second modified example of the vibrating section.

[0104] In the second modified example shown in Figure 23, the opposing sides (free ends) of each vibrating section 10A to 10D are formed in a bent shape consisting of multiple straight lines. In this case, compared to the case where the opposing sides of each vibrating section 10A to 10D are curved, resistance to manufacturing errors in the semiconductor process due to the anisotropy of the silicon crystal is improved. Furthermore, by making the sides of each vibrating section 10A to 10D bent, the degree of design freedom is increased. Moreover, by utilizing this degree of design freedom, the pressure that can be received by the tips of each vibrating section 10A to 10D can be further increased. As a result, a larger deflection angle can be generated, making it possible to improve the sensitivity of the vibration detection device.

[0105] [Examples of applications of the vibration detection device according to the present invention] Next, we will describe examples of applications of the vibration detection device according to the present invention.

[0106] <Vital Sensor> Figure 24 shows an example of applying the vibration detection device 1 according to the present invention to a vital sensor.

[0107] The vibration detection device 1 according to the present invention can be applied to a vital sensor that detects the pulse wave of the heartbeat with minimal noise. The vital sensor incorporating the vibration detection device 1 has a function to convert information related to various data such as heartbeat, heart rate (pulse rate), blood pressure, respiratory sounds, and respiratory rate detected by the vibration detection device 1 into vital data.

[0108] As shown in Figure 24, the vibration detection device 1 is installed on the ear (Figure 24(a)) or wrist (Figure 24(b)) and used as a vital sign sensor. There are also pulse wave sensors that use light to detect the heart rate, but such sensors cannot measure waveforms with high accuracy due to noise such as ambient light or fluctuations in the wearing state due to body movement, and are limited to limited applications such as pulse rate. In contrast, the piezoelectric vibration detection device 1 of the present invention detects the heart rate using sound, so it is possible to greatly reduce the generation of noise. Therefore, by using the vibration detection device 1 according to the present invention as a vital sign sensor, it is possible to perform high-precision analysis of frequency components from the detected pulse wave.

[0109] Furthermore, by analyzing the frequency components of the pulse wave using the vibration detection device 1 according to the present invention, it becomes possible to understand the psychological state with high accuracy. In addition, by applying machine learning to the analysis of frequency components, it may be possible to interpret information related to heart rate with high accuracy and estimate the psychological state from multiple perspectives.

[0110] Furthermore, a vital sensor to which the vibration detection device 1 according to the present invention is applied may be equipped with a system for detecting the psychological state of office workers working in an office. By wearing a vital sensor to which the vibration detection device 1 according to the present invention is applied during tasks such as meetings, programming, writing emails, and one-on-one meetings with a supervisor, it becomes possible to read the heart rate and detect the psychological state (such as stress levels and concentration levels).

[0111] Furthermore, a system for detecting psychological states to which the vibration detection device 1 according to the present invention is applied may have a UI that visualizes changes in psychological states such as concentration levels and stress levels. Specifically, by displaying in a graph or table how much stress and concentration levels change depending on the type of work, the user can intuitively understand the changes.

[0112] Furthermore, the system for detecting psychological state using the vibration detection device 1 according to the present invention may be configured to analyze situations in which concentration is possible (time of day, meeting partners, work environment) by utilizing machine learning. Through this analysis, the system can propose an optimal work environment to the user and support effective schedule creation. In addition, if concentration decreases and the user feels stressed, the system can issue an alarm to encourage relaxation.

[0113] <Pipe Sensor> Figure 25 shows an example of applying the vibration detection device 1 according to the present invention to a piping sensor.

[0114] The vibration detection device 1 according to the present invention can also be applied to a pipe sensor that detects the location of water leaks in pipes.

[0115] As shown in Figure 25, by installing the vibration detection device 1 according to the present invention on the surface (outer surface) of the pipe 200 and detecting vibrations transmitted to the surface of the pipe 200 using the vibration detection device 1, the location of water leaks in the pipe 200 can be detected. Piezoelectric sensors based on piezoelectric ceramics exist for inspecting pipes, but they have high acoustic impedance and limited sensitivity. In contrast, the vibration detection device 1 according to the present invention can be made more sensitive, as well as miniaturized and less expensive.

[0116] Furthermore, as shown in Figure 25, the vibration detection device 1 according to the present invention may be installed inside the pipe 200 and used as a hydrophone 2 that detects sound transmitted through the liquid flowing inside the pipe 200 as vibration. Since the hydrophone 2 detects sound transmitted through the pipe 200 from vibrations transmitted through the water, vibration attenuation can be suppressed, and vibration sources at greater distances can be detected compared to cases where vibrations are detected via air. When the vibration detection device 1 according to the present invention is used as a hydrophone 2, performance is improved by detecting low frequencies of several hundred Hz, making it possible to conduct inspections over long distances of up to 1 km, for example, and applicable to inspections of large-scale pipelines.

[0117] Furthermore, by installing the vibration detection device 1 according to the present invention on both the surface and the interior of the pipe 200 and using it as a microphone and hydrophone, the detection accuracy can be improved. The microphone and hydrophone transmit detection signals wirelessly to the computing device 201, and by synchronizing the signals in a time series, analysis of water leak locations and other information can be performed.

[0118] Although embodiments and modifications of the present invention have been described above, the present invention is not limited to the embodiments and modifications described above, and the design can be modified as appropriate without departing from the spirit of the invention.

[0119] In the embodiment described above, as shown in Figure 3, the first portion 31 is connected to the fixing portion 33 at the position of its base end 31a. However, the connection between the first portion 31 and the fixing portion 33 is not limited to the position of the base end 31a of the first portion 31. The connection point between the first portion 31 and the fixing portion 33 can be appropriately set to any position that is on the side of the base end 31a rather than the intermediate position in the extending direction (first direction P) of the first portion 31.

[0120] Similarly, the connection point between the first part 31 and the second part 32 is not limited to the position of the tip 31b of the first part 31 and the position of the base end 32a of the second part 32, but can be set as appropriate. Therefore, the connection point between the first part 31 and the second part 32 can be any position on the tip 31b side of the intermediate position in the extension direction (first direction P) of the first part 31, and any position on the base end 32a side of the intermediate position in the extension direction (second direction Q) of the second part 32.

[0121] Furthermore, while it is preferable for the first direction P, which is the extension direction of the first portion 31, and the second direction Q, which is the extension direction of the second portion 32, to be opposite directions from the viewpoint of miniaturization, as described above, they do not necessarily have to be opposite directions. For example, even if the first direction P and the second direction Q are orthogonal to each other, if the second portion 32 is connected to the tip 31b of the first portion 31 and is formed to widen toward the tip 32b side, the effects of the present invention, namely suppression of sensitivity reduction due to gap increase and improvement of sensitivity, can be achieved. Therefore, the first direction P and the second direction Q are not limited to being opposite directions, but may be different directions other than opposite directions.

[0122] Furthermore, depending on the layout of each vibrating part 10A to 10D, the fixing part 33 and the connecting part 34 may be made to appear as if they were not there. In that case, the first part 31 will be directly connected (fixed) to the support part 12, and the second part 32 will be directly connected (fixed) to the first part 31.

[0123] Furthermore, the number of vibrating sections 10A to 1D is not limited to four; it can be changed as needed, as long as there are multiple sections (two or more).

[0124] To summarize the embodiments of the present invention described above, the embodiments of the present invention include the following embodiments.

[0125] [First aspect] The first embodiment is a vibration detection device comprising a plurality of vibrating parts arranged point-symmetrically and a support part that supports the plurality of vibrating parts so as to be vibratable, wherein the plurality of vibrating parts have a first portion extending in a first direction from a fixed portion fixed to the support part, and a second portion connected to the first portion at the tip end in the first direction and extending in a second direction different from the first direction, and having a wider width at the tip end in the second direction than at the base end end connected to the first portion.

[0126] [Second aspect] In the second embodiment, in the first embodiment, the first direction and the second direction are opposite to each other.

[0127] [Third aspect] The third embodiment is, in the first or second embodiment, the length from the end of the connection portion between the first portion and the second portion on the fixing side to the part furthest toward the fixing portion is in the range of 0.25 times or more and 0.75 times or less the length from the end of the connection portion between the second portion and the first portion on the fixing side to the part furthest toward the tip side in the second direction.

[0128] [Fourth aspect] In the fourth embodiment, in any one of the first to third embodiments, the base end of the second portion of one of the adjacent vibrating parts is positioned opposite to the tip end of the second portion of the other vibrating part.

[0129] [Fifth aspect] A fifth embodiment is one of the first to fourth embodiments in which the first and second portions each have a piezoelectric film and two electrodes provided so as to sandwich the piezoelectric film, and wiring is connected to the two electrodes of either the first or second portion.

[0130] [Sixth aspect] The sixth embodiment is, in any one embodiment of the first to fourth, the first portion and the second portion each comprising a piezoelectric film and two electrodes provided so as to sandwich the piezoelectric film, wherein the electrode provided on one side of the piezoelectric film in the first portion and the electrode provided on the side of the piezoelectric film in the second portion facing the opposite side from the first side are connected via wiring, and the electrode provided on the other side of the piezoelectric film in the first portion and the electrode provided on the side of the piezoelectric film in the second portion facing the opposite side from the other side are connected via wiring.

[0131] [Seventh aspect] The seventh embodiment is one of the first to sixth embodiments, wherein the first portion extends in the first direction without bending in a direction intersecting the first direction from one end in the first direction to the other end opposite to it.

[0132] [Eighth aspect] The eighth embodiment is a vital sensor equipped with a vibration detection device according to any one of the first to seventh embodiments.

[0133] [Ninth aspect] The ninth embodiment is a piping sensor equipped with a vibration detection device according to any one of the first to seventh embodiments. [Explanation of symbols]

[0134] 1. Vibration detection device 4 Piezoelectric film 5 electrodes 6 electrodes 10 Vibration section 10A Vibration section 10B Vibration part 10C vibrating part 10D Vibration Unit 12 Support part 26 Wiring 27 Wiring 28 Wiring 29 Wiring 31 Part 1 31a proximal end 31b Tip 32 Part 2 32a proximal end 32b Tip 33 Fixed part 34 Connection part P First direction Q Second direction [Prior art documents] [Patent Documents]

[0135] [Patent Document 1] Patent No. 5936154

Claims

1. Multiple vibrating parts arranged symmetrically, The system includes a support portion that supports the plurality of vibrating parts so that they can vibrate, The aforementioned multiple vibrating parts are A first portion extending in a first direction from the fixing portion fixed to the support portion, A vibration detection device characterized by having a second portion which is connected to the first portion at the tip end in the first direction and extends in a second direction different from the first direction, and which is wider at the tip end in the second direction than at the base end end connected to the first portion.

2. The vibration detection device according to claim 1, wherein the first direction and the second direction are opposite to each other.

3. The vibration detection device according to claim 1, wherein the length from the end of the connection portion between the first portion and the second portion on the fixing side to the part furthest toward the fixing part is in the range of 0.25 times or more and 0.75 times or less the length from the end of the connection portion between the second portion and the first portion on the fixing side to the part furthest toward the tip side in the second direction.

4. The vibration detection device according to claim 1, wherein, among the vibrating parts arranged adjacent to each other, the base end side of the second portion of one vibrating part and the tip side of the second portion of the other vibrating part are arranged to face each other.

5. The first and second portions each have a piezoelectric film and two electrodes provided so as to sandwich the piezoelectric film. The vibration detection device according to claim 1, wherein wiring is connected to the two electrodes of either the first part or the second part.

6. The first and second portions each have a piezoelectric film and two electrodes provided so as to sandwich the piezoelectric film. The electrode provided on one side of the piezoelectric film in the first portion and the electrode provided on the side of the piezoelectric film in the second portion facing the opposite side are connected via wiring. The vibration detection device according to claim 1, wherein the electrode provided on the other surface of the piezoelectric film in the first portion and the electrode provided on the surface of the piezoelectric film in the second portion facing away from the other surface are connected via wiring.

7. The vibration detection device according to claim 1, wherein the first portion extends in the first direction without bending in a direction intersecting the first direction from one end in the first direction to the other end opposite to it.

8. A vital sensor equipped with the vibration detection device described in claim 1.

9. A piping sensor equipped with the vibration detection device described in claim 1.

Images