Vibration sensor

Abstract

To miniaturize a vibration sensor while suppressing shortage in energy and shortage in sensitivity.SOLUTION: A vibration sensor 10 includes a vibration transmission element 12 having a tip part 14 abutting on an object, a piezoelectric diaphragm 18 connected to a wire 28 for applying or taking out an electric signal, and a case body 32 that houses the vibration transmission element 12 and the piezoelectric diaphragm 18 inside and has a projecting hole 36 in which the tip part 14 projects. The vibration transmission element 12 and the piezoelectric diaphragm 18 are connected electrically and physically, and the vibration transmission element 12 is set to the ground potential. For this reason, while vibration is being transmitted directly between the vibration transmission element 12 and the piezoelectric diaphragm 18, noise caused by the vibration transmission element 12 abutting on an object can be reduced greatly. Accordingly, since a required S / N ratio can be ensured, shortage in energy and shortage in sensitivity can be suppressed, thus contributing to miniaturization of the vibration sensor 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vibration sensor for applying vibration to an object or receiving vibration from an object.

Background Art

[0002] Conventionally, various sensors used in various applications have always been required to be miniaturized. For example, a vibration sensor using a piezoelectric vibration plate for generating or receiving vibration, which is used in a tile peeling detection device or the like, is one of them. As a result of requiring multiple installations on the device for efficient inspection, miniaturization of the vibration sensor has become essential. Note that Patent Document 1 discloses a technique related to miniaturization of a piezoelectric vibration plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in order to miniaturize the vibration sensor as described above, it is necessary to use a piezoelectric vibration plate having a smaller area than the conventional one. However, when the area of the piezoelectric vibration plate becomes small, there is a risk of insufficient energy in the application of generating vibration and insufficient sensitivity in the application of receiving vibration, and countermeasures for these are required. The present invention has been made in view of the above problems, and an object thereof is to miniaturize a vibration sensor while suppressing insufficient energy and insufficient sensitivity.

Means for Solving the Problems

[0005] (Aspect of the Invention) The following aspects of the invention illustrate the configuration of the present invention and are described separately by item for the purpose of facilitating the understanding of various configurations of the present invention. Each item does not limit the technical scope of the present invention, and even when a part of the components of each item is replaced, deleted, or other components are added while taking into account the best mode for implementing the invention, it may be included in the technical scope of the present invention.

[0006] (1) A vibration sensor for applying vibration to an object or receiving vibration from the object, including a vibration transmission member having a tip portion that abuts against the object, a piezoelectric vibration plate connected to a wiring for applying or extracting an electrical signal, and a case body that houses the vibration transmission member and the piezoelectric vibration plate therein and has a protruding hole through which the tip portion protrudes, wherein the vibration transmission member and the piezoelectric vibration plate are electrically and physically connected, and the vibration transmission member is set to a ground potential (Claim 1).

[0007] The vibration sensor described in this item is for applying vibration to an object or receiving vibration from the object, and includes a vibration transmission member, a piezoelectric vibration plate, and a case body. The vibration transmission member has a tip portion that abuts against the object, which is the output destination or input source of vibration, and transmits vibration to the object or captures vibration from the object through the tip portion. The piezoelectric vibration plate is connected to a wiring for applying or extracting an electrical signal, and generates vibration from the electrical signal applied from the wiring, or converts the vibration into an electrical signal and transmits it to the wiring. The case body houses the vibration transmission member and the piezoelectric vibration plate therein, and at this time, the vibration transmission member and the piezoelectric vibration plate are housed in such a manner that the tip portion of the vibration transmission member protrudes from the protruding hole formed in the case body.

[0008] In addition, the vibration transmitter and the piezoelectric vibration plate are electrically and physically connected. By being physically connected, vibration is directly transmitted between the vibration transmitter and the piezoelectric vibration plate. That is, in the application of applying vibration to an object, vibration is generated by the piezoelectric vibration plate from the electrical signal applied from the wiring, and the generated vibration is directly transmitted from the piezoelectric vibration plate to the vibration transmitter, and further from the vibration transmitter to the object. On the contrary, in the application of receiving vibration from an object, the vibration from the object is taken in through the vibration transmitter, and the vibration is directly transmitted from the vibration transmitter to the piezoelectric vibration plate, and the further transmitted vibration is converted into an electrical signal by the piezoelectric vibration plate and transmitted to the wiring.

[0009] Furthermore, the vibration transmitter and the piezoelectric vibration plate are electrically connected, and the vibration transmitter is set to the ground potential. That is, the vibration transmitter is electrically connected to one of the two electrodes of the piezoelectric vibration plate, and the ground potential is added to that one electrode via a wiring. In this way, by setting the vibration transmitter to the ground potential, the noise caused by the vibration transmitter coming into contact with the object is significantly reduced. As a result, even if an event such as a small piezoelectric vibration plate occurs where the level of the electrical signal converted by the piezoelectric vibration plate from the captured vibration is small, the necessary signal-to-noise ratio, etc. is ensured by the above-mentioned noise countermeasures, so that energy shortage and sensitivity shortage are suppressed, and it contributes to the miniaturization of the vibration sensor.

[0010] (2) In the above item (1), the vibration transmitter and the piezoelectric vibration plate are slidably accommodated inside the case body in a direction parallel to the protruding direction of the tip portion, and are biased by a spring in the protruding direction (Claim 2). The vibration sensor described in this item has a vibration transmission element and a piezoelectric vibration plate housed inside a case body, and the tip of the vibration transmission element is slidably housed in a direction parallel to the direction in which the tip protrudes from the protruding hole of the case body. Further, the vibration transmission element and the piezoelectric vibration plate are biased by a spring in the protruding direction of the tip of the vibration transmission element, which is one of the slidable directions. Therefore, when the tip of the vibration transmission element comes into contact with an object, the vibration transmission element and the piezoelectric vibration plate connected thereto are slightly slid in the direction opposite to the protruding direction of the tip inside the case body while being biased by the spring in the direction of the object. As a result, even if there are irregularities on the object, the tip of the vibration transmission element surely comes into contact with the object, and even when a plurality of vibration sensors are simultaneously brought into contact with the object, the loads on all the vibration sensors come into contact with the object in a state where the loads are substantially equal.

[0011] (3) In the above item (2), a vibration sensor (claim 3) in which a first damper member is interposed between the vibration transmission element and the piezoelectric vibration plate and the sliding surface inside the case body. The vibration sensor described in this item has a first damper member interposed between a vibration transmission element and a piezoelectric vibration plate that are slidably housed inside a case body and the sliding surface inside the case body. As a result, when used for applying vibration to an object, the vibration generated by the piezoelectric vibration plate is suppressed from being transmitted to the case body through the sliding surface of the case body, and when used for receiving vibration from an object, the vibration of the case body due to an external factor is suppressed from being transmitted to the piezoelectric vibration plate through the sliding surface of the case body. Here, for example, in a tile peeling detection device, etc., a vibration sensor for applying vibration to an object and a vibration sensor for receiving vibration from the object are simultaneously fixed to a base member and used. The vibration sensor described in this item, even when used for such applications, has the first damper member interposed as described above, so that the vibration generated by the piezoelectric vibration plate of the vibration sensor for applying vibration is prevented from being transmitted to the vibration sensor for receiving vibration through the case body or the base member of that vibration sensor, and false detection due to vibration interference is prevented.

[0012] (4) In the above items (2) and (3), a vibration sensor in which a second damper member is disposed between an edge portion on the inner side of the case body of the protruding hole and the vibration transmitter (Claim 4). The vibration sensor described in this item is one in which a second damper member is disposed between an edge portion on the inner side of the case body of a protruding hole provided in the case body and the vibration transmitter. That is, since the tip of the vibration transmitter is biased by a spring in the direction of protruding from the protruding hole of the case body, it is pressed against the above-described edge portion of the protruding hole, and even when the tip of the vibration transmitter is in contact with the object, it may partially contact the edge portion of the protruding hole. Therefore, by disposing the second damper member at the above-described position, the vibration generated by the piezoelectric vibration plate is prevented from being transmitted to the case body through the edge portion of the protruding hole, and the vibration of the case body due to an external factor is prevented from being transmitted to the piezoelectric vibration plate. For this reason, even when used simultaneously for the two uses as described in item (3) above, the vibration generated by the piezoelectric vibration plate of the vibration sensor that applies vibration is prevented from being transmitted to the vibration sensor that receives vibration through the case body or the base member of the vibration sensor, and false detection due to vibration interference is prevented.

[0013] (5) In the above items (1) to (4), a vibration sensor including two piezoelectric vibration plates, the two piezoelectric vibration plates being electrically and physically connected face to face with a metal electrode plate interposed therebetween, an electrical signal being applied to the two piezoelectric vibration plates through the wiring, and the vibration sensor being used as a vibration exciter that applies vibration to the object through the vibration transmitter (Claim 5). The vibration sensor described in this item is used as a vibration exciter that applies vibration to an object, and includes two piezoelectric vibration plates. The two piezoelectric vibration plates are electrically and physically connected face to face with a metal electrode plate interposed therebetween. For this reason, a vibration transmitter is physically and electrically connected to one of the two piezoelectric vibration plates, and the other piezoelectric vibration plate is electrically connected, and their connection destinations are the electrodes of the respective piezoelectric vibration plates to which a ground potential is applied.

[0014] In addition, the metal electrode plate sandwiched between the two piezoelectric vibrating plates serves as an electrode different from the electrode to which the ground potential is applied among the two electrodes of the piezoelectric vibrating plate, and a potential paired with the ground potential is applied via a wiring. Therefore, when an electrical signal is applied via the wiring to the two piezoelectric vibrating plates connected facing each other with the metal electrode plate in between, both of them will vibrate simultaneously, and the vibration generated will be increased compared to the case of a single piezoelectric vibrating plate. As a result, even if the piezoelectric vibrating plate becomes smaller, vibrations with increased energy are generated by the two piezoelectric vibrating plates, thus suppressing the energy shortage that is a concern when the piezoelectric vibrating plate becomes smaller, and enabling the vibration sensor to be miniaturized. Furthermore, if an electrical signal amplified by a power amplifier or the like is used as the electrical signal applied to the vibration sensor, even if the vibration sensor is miniaturized, vibrations of a sufficient magnitude required as the vibrations applied to the object will be generated.

[0015] (6) The vibration sensor according to claim 6, which includes one piezoelectric vibrating plate, receives vibration from the object via the vibration transmitter, and extracts an electrical signal from the one piezoelectric vibrating plate via the wiring. The vibration sensor described in this section is used as a vibration receiving sensor and includes one piezoelectric vibrating plate. Therefore, the vibration received from the object via the vibration transmitter is transmitted to the one piezoelectric vibrating plate physically connected to the vibration transmitter, and the electrical signal converted by the piezoelectric vibrating plate from the transmitted vibration is extracted via the wiring. And if the extracted electrical signal is amplified by, for example, a charge amplifier, even if the vibration receiving sensor is miniaturized, combined with the noise countermeasures as described in section (1) above, an electrical signal of a sufficient magnitude for analysis can be obtained, thus eliminating the sensitivity shortage that is a concern when the piezoelectric vibrating plate becomes smaller.

Advantages of the Invention

[0016] Since the present invention has the above-described configuration, it is possible to miniaturize the vibration sensor while suppressing energy shortage and sensitivity shortage.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments for carrying out the present invention will be described based on the accompanying drawings. Here, detailed description will be omitted for the same parts or corresponding parts as the prior art, and the same parts or corresponding parts are denoted by the same reference numerals throughout the drawings. Figures 1 to 6 show the structure of the vibration sensor 10 according to an embodiment of the present invention. First, the vibration sensor 10 shown in FIG. 1 is used as a vibration sensor 10A that applies vibration to an object, and is illustrated in a state of being fixed to a base portion 62, which will be described later, by screwing or the like. Here, although not limited thereto, the object to which vibration is applied will be described as the tile T shown in FIG. 7. FIG. 1(a) is a plan view of the vibration sensor 10A, and FIG. 1(b) is an image cross-sectional view in which a part of the vibration sensor 10A is broken when viewed from the side. As shown in the figure, the vibration sensor 10A includes a vibration transmission member 12, a piezoelectric vibration plate 18, a case body 32, a sliding member 50, a spring 52, a first damper member 54, and a second damper member 56.

[0019] The case body 32 houses most of the other components of the vibration sensor 10A, and has a configuration in which a lid portion 34 and a bottom portion 44 that are circular in plan view are connected to both open ends of a cylindrical wall portion 40 by screwing or the like, and an accommodation space surrounded by them is formed inside. Further, a protruding hole 36 for the vibration transmission member 12 is formed in the lid portion 34, and through holes (not shown) for wiring 28 and the like, which will be described later, are formed in the bottom portion 44. The case body 32 is formed of, for example, various resins, and in particular, the bottom portion 44 interposed between the case body 32 and the base portion 62 of the mounting destination is formed of a material having elasticity such as rubber, so that it functions as a damper member (third damper member) 44 that suppresses the transmission of vibration between the vibration sensor 10 and the base portion 62. In addition, an attachment screw for fixing the vibration sensor 10 to the base portion 62 may be inserted only into the base portion 62 and the bottom portion 44 of the case body 32, so that the attachment screw is floated by the bottom portion 44. Further, although not limited thereto, the outer diameter of the case body 32 is, for example, about 24 mm.

[0020] As shown also in Fig. 2, the vibration transmitter 12 has a conical tip portion 14 with a rounded tip, a cylindrical portion 15 connected to the lower end of the tip portion 14, and a disk portion 16 connected to the lower end of the cylindrical portion 15 and having a diameter larger than that of the cylindrical portion 15. A cylindrical internal space is formed that penetrates the disk portion 16 and extends to the cylindrical portion 15. The vibration transmitter 12 of the vibration sensor 10A transmits the vibration generated by the piezoelectric vibration plate 18, as will be described later, to the tile T with its tip portion 14 in contact with the tile T. Further, the vibration transmitter 12 also serves to match the acoustic impedances of the piezoelectric vibration plate 18 and the tile T by having the above-described shape. The vibration transmitter 12 is formed of a material such as a metal having conductivity, for example.

[0021] Also, inside the case body 32, the vibration transmitter 12 is biased upward in Fig. 1(b) by a spring 52, as will be described later, and a part of its cylindrical portion 15 and the tip portion 14 project outside the case body 32 from a protruding hole 36 provided in the lid portion 34 of the case body 32. That is, the protruding hole 36 has an inner diameter larger than the outer diameter of the cylindrical portion 15 and smaller than the outer diameter of the disk portion 16. In such a state, a second damper member 56 is interposed between the upper surface of the disk portion 16 and the edge portion 36a of the protruding hole 36 of the lid portion 34. The second damper member 56 is an annular member attached to the disk portion 16 side and through which the cylindrical portion 15 is inserted in the present embodiment, and is configured to move in the vertical direction in Fig. 1(b) together with the vibration transmitter 12. The second damper member 56 is formed of a material having elasticity such as rubber, for example, and is configured to suppress the transmission of vibration between the vibration transmitter 12 and the lid portion 34 (case body 32).

[0022] The piezoelectric diaphragm 18, also referred to here as the excitation piezoelectric diaphragm 18, has a configuration in which two piezoelectric diaphragms 18a and 18b are connected with a metal electrode plate 24 interposed therebetween, as shown in FIG. 2. That is, referring also to FIG. 3, in the present embodiment, the two piezoelectric diaphragms 18a and 18b each have a ceramic plate 20 and a metal plate 22, and the ceramic plate 20 sides of both are facing each other and are electrically and physically connected to the metal electrode plate 24. Further, the metal plate 22 of the piezoelectric diaphragm 18a and the metal plate 22 of the piezoelectric diaphragm 18b are electrically connected via a connection portion 25. It should be noted that it is desirable to use commercially available piezoelectric diaphragms for each of the two piezoelectric diaphragms 18a and 18b from the viewpoint of cost reduction, and although not limited thereto, the outer diameter of the piezoelectric diaphragms 18a and 18b is about 12 mm.

[0023] Then, two wirings 28 are connected to the metal electrode plate 24 and one metal plate 22 (the metal plate 22 of the piezoelectric diaphragm 18b in the present embodiment) by soldering or the like, so that two paired potentials (illustrated as “+” and “−” in FIG. 3) are added to the ceramic plate 20 side and the metal plate 22 side of the two piezoelectric diaphragms 18a and 18b. At this time, a ground potential is added to the metal plate 22 side. Further, to the metal plate 22 of the piezoelectric diaphragm 18a located above in the figure among the two piezoelectric diaphragms 18a and 18b, the disk portion 16 of the vibration transmitter 12 is electrically and physically connected by, for example, paste solder or an epoxy-based adhesive. For this reason, a ground potential is added to the vibration transmitter 12 via one wiring 28 and the metal plate 22.

[0024] Referring to FIGS. 1 and 2, a first damper member 54 is disposed on the lower side (the piezoelectric diaphragm 18b side) of the piezoelectric diaphragm 18 for excitation in the drawing. As shown in FIG. 2, the first damper member 54 of the present embodiment is composed of a first member 54a divided into two in a direction perpendicular to the paper surface and a cylindrical second member 54b. An annular shim 57 is disposed below the second member 54b. The vibration transmitter 12, the second damper member 56, the piezoelectric diaphragm 18 for excitation, the first damper member 54, and the shim 57 shown in FIG. 2 are, as shown in FIG. 1, such that the first damper member 54 and the shim 57 are accommodated in a cup-shaped sliding member 50, and can slide in the vertical direction in the drawing along the sliding surface 40a inside the case body 32 via the sliding member 50.

[0025] Also, between the sliding member 50 and the bottom portion 44 of the case body 32, a spring 52 is installed to bias the members shown in FIG. 2 upward in the drawing together with the sliding member 50. For this reason, in the normal state, the vibration transmitter 12 is pressed against the lid portion 34 of the case body 32 with the second damper member 56 interposed therebetween. Further, the first damper member 54 disposed at the position as described above is formed of a material having elasticity such as rubber, for example, so as to suppress the transmission of vibration between the piezoelectric diaphragm 18 and the sliding member 50, in other words, between the piezoelectric diaphragm 18 and the case body 32.

[0026] In the excitation sensor 10A having the above-described configuration, when an electrical signal for generating vibration is applied to the piezoelectric diaphragm 18 via the wiring 28 in a state where the tip portion 14 of the vibration transmitter 12 is in contact with the tile T, vibration is generated by the piezoelectric diaphragm 18. Then, the generated vibration is transmitted to the tile T via the vibration transmitter 12 physically connected to the piezoelectric diaphragm 18, and vibration is applied to the tile T. Here, referring to FIGS. 1 and 2, the wiring 28 connected to the piezoelectric diaphragm 18 is routed from the piezoelectric diaphragm 18, for example, through the gap between the two divided first members 54a, the central hole of the cylindrical second member 54b, the central hole of the annular shim 57, the through hole provided in the sliding member 50, and the through hole provided in the bottom portion 44, from the inside of the case body 32 to the outside.

[0027] Next, the vibration sensor 10 according to an embodiment of the present invention, which is used as a vibration receiving sensor 10B that receives vibration from an object (tile T) shown in FIGS. 4 to 6, will be described. However, the vibration receiving sensor 10B differs only in the configuration of the piezoelectric vibration plate 18 from the vibration exciting sensor 10A shown in FIGS. 1 to 3. For this reason, the points regarding the piezoelectric vibration plate 18 will be described here, and the description of the components having the same configuration as the vibration exciting sensor 10A will be omitted. The piezoelectric vibration plate 18 of the vibration receiving sensor 10B is also referred to here as a piezoelectric vibration plate 18 for vibration reception, and as shown in FIGS. 5 and 6, it is composed of a single piezoelectric vibration plate 18. Then, two wirings 28 are connected to the ceramic plate 20 side and the metal plate 22 side of the single piezoelectric vibration plate 18 by soldering or the like, so that two potential pairs (illustrated as “+” and “-” in FIG. 6) are added thereto. At this time, a ground potential is added to the metal plate 22 side.

[0028] Also, the disk portion 16 of the vibration transmitter 12 is electrically and physically connected to the metal plate 22 of the piezoelectric vibration plate 18 for vibration reception by, for example, a silver paste and an epoxy-based adhesive or a conductive adhesive. For this reason, a ground potential is added to the vibration transmitter 12 via one of the wirings 28 and the metal plate 22. A first damper member 54 and a shim 57 are arranged below the piezoelectric vibration plate 18 for vibration reception in the drawing. In the vibration receiving sensor 10B having such a configuration, when the tile T is vibrating with the tip portion 14 of the vibration transmitter 12 in contact with the tile T, the vibration is transmitted to the vibration transmitter 12 and further transmitted to the piezoelectric vibration plate 18 physically connected to the vibration transmitter 12. Then, the transmitted vibration is converted into an electrical signal by the piezoelectric vibration plate 18, and it is taken out as a vibration receiving electrical signal via the wiring 28.

[0029] Next, FIG. 7 schematically shows the configuration of the tile detachment detector 60 using the vibration sensor 10 according to the embodiment of the present invention as described above. As shown in the figure, the tile detachment detector 60 is for detecting the detachment of the tile T used in a building, and includes a vibration input unit 66, a plurality of vibration sensors 10, and an analysis unit 74. The plurality of vibration sensors 10 includes, in this embodiment, one excitation sensor 10A and six vibration receiving sensors 10B. The excitation sensor 10A is for applying vibration to the tile T in a state where the vibration transmission member 12 is in contact with the tile T as an object, as described with reference to FIGS. 1 to 3. The vibration receiving sensor 10B is for receiving vibration from the tile T in a state where the vibration transmission member 12 is in contact with the tile T as an object, as described with reference to FIGS. 4 to 6.

[0030] The plurality of vibration sensors 10 described above are fixed to the plate-shaped base portion 62 in a positional relationship as shown in FIG. 8, for example. That is, as can be confirmed in FIG. 8(b), one excitation sensor 10A is fixed near the center of the base portion 62 that forms a rectangle in plan view, and six vibration receiving sensors 10B are arranged so as to surround the excitation sensor 10A. More specifically, one excitation sensor 10A and six vibration receiving sensors 10B are arranged in a staggered grid pattern centered on the excitation sensor 10A at substantially equal intervals. Such an arrangement is adapted to a tile T having a size and shape as shown by the two-dot chain line in FIG. 8(b), and although not limited thereto, the size of the tile T is, for example, 95 mm × 45 mm. As an example of the size of the corresponding base portion 62, the horizontal width W shown in FIG. 8(b) is about 130 mm, and the vertical width D is about 95 mm.

[0031] Also, each of the vibration excitation sensor 10A and the vibration reception sensor 10B is fixed to the base portion 62 by screwing or the like via the third damper member (the bottom portion of the case body 32) 44. On both ends of the surface of the base portion 62 opposite to the surface on which the plurality of vibration sensors 10 are attached, two U-shaped gripping members 86 are attached. Note that Fig. 8(a) shows an image cross-section near the vertical center in Fig. 8(b), and Fig. 8(c) shows an image cross-section near the horizontal center in Fig. 8(b), but the illustration of the inside of each vibration sensor 10 is omitted.

[0032] Returning to Fig. 7, the vibration input section 66 is for applying an electric signal for generating vibration to the vibration excitation sensor 10A. In the present embodiment, it includes a signal generator 68 and a power amplifier 70. The signal generator 68 generates an electric signal for generating vibration. In the present embodiment, as such an electric signal, for example, a single-shot pulse wave of a sine half-wave (half-sine wave) 90 as shown in Fig. 9 is repeatedly generated. Although not limited thereto, the sine half-wave 90 has, for example, a frequency of 14 kHz, an output voltage of 10 Vp-p, and a duty cycle of 80 ms. Also, the power amplifier 70 amplifies the electric signal generated by the signal generator 68. For example, when an electric signal of 10 Vp-p is generated by the signal generator 68, it amplifies it to about 50 Vp-p to 100 Vp-p. Then, the electric signal for generating vibration amplified in this way is applied to the vibration excitation sensor 10A via the wiring 28 or the like. Any signal generator and power amplifier may be used for the signal generator 68 and the power amplifier 70.

[0033] The analysis unit 74 is for analyzing the electrical signals received from each of the vibration sensors 10B via the wiring 28 or the like. In this embodiment, it includes a charge amplifier 76, an AD converter 78, an FFT analysis unit 80, and a display unit 82. The charge amplifier 76 amplifies the vibration electrical signals received from the vibration sensors 10B, and amplifies the vibration electrical signals to the voltage required for analysis. At this time, a high-pass filter may be used to remove low-frequency components such as ambient vibrations. Also, it is preferable to take noise countermeasures as much as possible for the path from the vibration sensor 10B to the charge amplifier 76 and the charge amplifier 76. Any multi-channel charge amplifier may be used for the charge amplifier 76.

[0034] The AD converter 78 converts the vibration electrical signals amplified by the charge amplifier 76 from analog signals to digital signals, and performs the conversion at the sampling rate and resolution required for the FFT analysis described later. For example, when the signal generator 68 generates a sine half-wave 90 with a frequency of 14 kHz, sampling may be performed at about 40 kHz, and the resolution may be about 16 bits. Also, since the AD converter 78 AD-converts each of the vibration electrical signals from the plurality of vibration sensors 10B amplified by the charge amplifier 76, any multi-channel AD conversion device having the above performance is used.

[0035] The FFT analysis unit 80 performs FFT analysis on the received vibration electrical signal converted into a digital signal by the AD converter 78, and is configured by, for example, an arbitrary computer installed with software for performing FFT analysis. In the FFT analysis, the digital signal from the AD converter 78 is decomposed into frequency components by fast Fourier transform, and the peeling state of the tile T is inferred from the peak frequency and peak voltage of the result. Further, the FFT analysis unit 80 individually performs FFT analysis on the received vibration electrical signals from the plurality of vibration sensors 10B, and estimates the portion where peeling has occurred in the tile T using the positional relationship between each vibration sensor 10B and the excitation sensor 10A. At this time, it may be determined whether the tile T is soundly adhered according to the position and degree where peeling is estimated to have occurred. The display unit 82 displays the analysis results in the FFT analysis unit 80 and the like, and an arbitrary display device is used.

[0036] When in use, in the tile peeling detector 60 configured as described above, as shown in FIG. 8, a plurality of vibration sensors 10 fixed to the base portion 62 are pressed against the tile T, for example, with the position indicated by the two-dot chain line in FIG. 8(b) as a guide, and the vibration transmitters 12 of all the vibration sensors 10 are brought into contact with the tile T. In this state, a sine half-wave 90 as shown in FIG. 9 is generated from the signal generator 68 of the vibration input unit 66, amplified by the power amplifier 70, and applied to the excitation sensor 10A. The excitation sensor 10 generates vibration from the applied electrical signal and applies it to the tile T. Then, in the portion where the tile T is not peeled, since the vibration also propagates to the adhesion destination of the tile T, the vibration energy becomes small and propagates inside the tile T. In the portion where the tile T is peeled, since the vibration propagating to the adhesion destination of the tile T is small, the vibration propagates inside the tile T with little loss of vibration energy. In this way, the vibration propagated inside the tile T is received by each vibration sensor 10B, converted into an electrical signal, and sent to the analysis unit 74. In the analysis unit 74, the electrical signals from the plurality of vibration sensors 10 are amplified by the charge amplifier 76, converted into digital signals by the AD converter 78, and then subjected to FFT analysis by the FFT analysis unit 80, and estimation of tile T peeling and the like are performed.

[0037] Here, the vibration sensor 10 according to the embodiment of the present invention is not limited to the configuration shown in FIGS. 1 to 6, and depending on the object or situation to which vibration is applied or received, some of the components shown in FIGS. 1 to 6 may be deleted, changed, or appropriately added. That is, the object of the vibration sensor 10 may be other than the tile T, and for example, it may be used for applications that apply vibration to or receive vibration from various members used in buildings or the like. Further, the shapes and sizes of the vibration transmission member 12, the case body 32, the sliding member 50, and the respective damper members 44, 54, and 56 may be arbitrarily set according to the use and purpose of the vibration sensor 10 and the like.

[0038] On the other hand, the configuration of the tile detachment detector 60 using the vibration sensor 10 according to the embodiment of the present invention is not limited to the configuration shown in FIG. 7, and depending on the tile T to be inspected and the situation, etc., some of the components shown in FIG. 7 may be deleted, changed, or appropriately added. For example, the number and positional relationship of the excitation sensor 10A and the vibration receiving sensor 10B among the plurality of vibration sensors 10 may be changed according to the size of the tile T and the like. As an example, the number and position of the excitation sensor 10A and the vibration receiving sensor 10B in the example of FIG. 8(b) may be interchanged. Further, four or eight vibration receiving sensors 10B or excitation sensors 10A may be arranged so as to surround the excitation sensor 10A or the vibration receiving sensor 10B, and both the excitation sensor 10A and the vibration receiving sensor 10B may be included in plural.

[0039] Furthermore, by swapping the connection destinations of the wiring 28 of the excitation sensor 10A and the connection destinations of the wiring 28 of the vibration receiving sensor 10B, it is possible to swap only the roles of applying or receiving vibration without physically exchanging the positions of the excitation sensor 10A and the vibration receiving sensor 10B. Also, the electrical signal input from the vibration input unit 66 to the excitation sensor 10A is not limited to the sine half-wave 90 as shown in FIG. 9, and other shaped single-shot pulse waves or sweep waves may be input. In addition, for example, a configuration for use with one tile T as shown in FIG. 8 is prepared in a plurality of sets including other necessary components in FIG. 7, and they are combined in a positional relationship that matches the array of tiles T to be inspected, so that a plurality of tiles T can be inspected simultaneously.

[0040] Now, according to the embodiment of the present invention having the above configuration, the following operational effects can be obtained. That is, the vibration sensor 10 according to the embodiment of the present invention is for applying vibration to an object (for example, the tile T in FIG. 7) or receiving vibration from the object, and as shown in FIGS. 1 and 4, includes a vibration transmission member 12, a piezoelectric vibration plate 18, and a case body 32. The vibration transmission member 12 has a tip portion 14 that is brought into contact with an object that is the output destination or input source of vibration, and transmits vibration to the object or takes in vibration from the object through the tip portion 14. The piezoelectric vibration plate 18 is connected to a wiring 28 for applying or extracting an electrical signal, and generates vibration from the electrical signal applied from the wiring 28, or converts the vibration into an electrical signal and transmits it to the wiring 28. The case body 32 houses the vibration transmission member 12 and the piezoelectric vibration plate 18 therein, and at this time, the vibration transmission member 12 and the piezoelectric vibration plate 18 are housed in such a manner that the tip portion 14 of the vibration transmission member 12 protrudes from the protruding hole 36 formed in the case body 32.

[0041] In addition, the vibration transmitter 12 and the piezoelectric vibrating plate 18 are electrically and physically connected. By being physically connected, vibration is directly transmitted between the vibration transmitter 12 and the piezoelectric vibrating plate 18. That is, in the application of applying vibration to an object, vibration is generated by the piezoelectric vibrating plate 18 from the electrical signal applied from the wiring 28, and the generated vibration is directly transmitted from the piezoelectric vibrating plate 18 to the vibration transmitter 12, and further the vibration is transmitted from the vibration transmitter 12 to the object. On the other hand, in the application of receiving vibration from an object, the vibration from the object is taken in via the vibration transmitter 12, the vibration is directly transmitted from the vibration transmitter 12 to the piezoelectric vibrating plate 18, and the transmitted vibration is converted into an electrical signal by the piezoelectric vibrating plate 18 and transmitted to the wiring 28.

[0042] Furthermore, the vibration transmitter 12 and the piezoelectric vibrating plate 18 are electrically connected, and the vibration transmitter 12 is set to the ground potential. That is, as shown in FIGS. 3 and 6, the vibration transmitter 12 is electrically connected to one of the two electrodes of the piezoelectric vibrating plate 18, and the ground potential is added to the one electrode via the wiring 28. In this way, by setting the vibration transmitter 12 to the ground potential, the noise caused by the vibration transmitter 12 coming into contact with the object can be significantly reduced. As a result, even if an event such as a small level of the electrical signal converted by the piezoelectric vibrating plate 18 from the captured vibration occurs when the piezoelectric vibrating plate 18 is small, the necessary S / N ratio and the like can be ensured by the above-described noise countermeasures. Therefore, it is possible to contribute to the miniaturization of the vibration sensor 10 while suppressing energy shortage and sensitivity shortage.

[0043] Also, as shown in FIGS. 1 and 4, in the vibration sensor 10 according to the embodiment of the present invention, a vibration transmission member 12 and a piezoelectric vibration plate 18 housed inside a case body 32 are slidably housed in a direction parallel to the direction in which the tip portion 14 of the vibration transmission member 12 protrudes from the protruding hole 36 of the case body 32 (the vertical direction in the figure). Further, the vibration transmission member 12 and the piezoelectric vibration plate 18 are biased by a spring 52 in the protruding direction of the tip portion 14 of the vibration transmission member 12, which is one direction in which they can slide. For this reason, when the tip portion 14 of the vibration transmission member 12 comes into contact with an object, the vibration transmission member 12 and the piezoelectric vibration plate 18 connected thereto are slightly slid in the direction opposite to the protruding direction of the tip portion 14 (the downward direction in the figure) inside the case body 32, and are in a state of being biased by the spring 52 in the direction of the object. As a result, even if there are irregularities or the like on the object, the tip portion 14 of the vibration transmission member 12 can be surely brought into contact with the object, and even when a plurality of vibration sensors 10 are simultaneously brought into contact with the object, the object can be brought into contact with the load on all the vibration sensors 10 being made substantially uniform.

[0044] Furthermore, in the vibration sensor 10 according to the embodiment of the present invention, a first damper member 54 is interposed between the vibration transmission member 12 and the piezoelectric vibration plate 18 that are slidably housed inside the case body 32 and the sliding surface 40a inside the case body 32. In the illustrated example, the first damper member 54 is interposed between the vibration transmission member 12 and the piezoelectric vibration plate 18 and the sliding member 50. Thereby, in the case of an application for applying vibration to an object, it is possible to suppress the vibration generated by the piezoelectric vibration plate 18 from being transmitted to the case body 32 via the sliding surface 40a of the case body 32, and in the case of an application for receiving vibration from an object, it is possible to suppress the vibration of the case body 32 due to an external factor from being transmitted to the piezoelectric vibration plate 18 via the sliding surface 40a of the case body 32.

[0045] Here, for example, in a tile detachment detector 60 (see FIGS. 7 and 8), a vibration sensor 10A that applies vibration to an object and a vibration receiving sensor 10B that receives vibration from the object are simultaneously fixed to a base portion 62 and used. Even when the vibration sensor 10 according to the embodiment of the present invention is used for such applications, since the first damper member 54 as described above is interposed, the vibration generated by the piezoelectric vibration plate 18 of the vibration sensor 10A can be prevented from being transmitted to the vibration receiving sensor 10B through the case body 32 or the base portion 62 of the vibration sensor 10A, and false detection due to vibration interference can be prevented.

[0046] Further, in the vibration sensor 10 according to the embodiment of the present invention, a second damper member 56 is disposed between an edge portion 36a on the inner side of the case body 32 of a protruding hole 36 provided in the case body 32 and the vibration transmitter 12. That is, since the tip portion 14 of the vibration transmitter 12 is biased by the spring 52 in the direction in which it protrudes from the protruding hole 36 of the case body 32, it is pressed against the edge portion 36a of the protruding hole 36 described above. Even when the tip portion 14 of the vibration transmitter 12 is in contact with the object, it may partially contact the edge portion 36a of the protruding hole 36. Therefore, by disposing the second damper member 56 at the position as described above, it is possible to suppress the vibration generated by the piezoelectric vibration plate 18 from being transmitted to the case body 32 through the edge portion 36a of the protruding hole 36, and the vibration of the case body 32 due to an external factor from being transmitted to the piezoelectric vibration plate 18. For this reason, even when it is simultaneously used for two applications such as in the tile detachment detector 60, the vibration generated by the piezoelectric vibration plate 18 of the vibration sensor 10A that applies vibration can be prevented from being transmitted to the vibration receiving sensor 10B that receives vibration through the case body 32 or the base portion 62 of the vibration sensor 10A, and false detection due to vibration interference can be prevented.

[0047] In addition, when the vibration sensor 10 according to the embodiment of the present invention is used as a vibration excitation sensor 10A for applying vibration to an object as shown in FIGS. 1 to 3, it includes two piezoelectric vibration plates 18a and 18b. And those two piezoelectric vibration plates 18a and 18b are electrically and physically connected face to face with a metal electrode plate 24 interposed therebetween. For this reason, a vibration transmission element 12 is physically and electrically connected to one of the two piezoelectric vibration plates 18a and 18b, and the other piezoelectric vibration plate 18b is electrically connected, and their connection destinations are the electrodes of each piezoelectric vibration plate 18 to which a ground potential is added. Further, the metal electrode plate 24 sandwiched between the two piezoelectric vibration plates 18a and 18b serves as an electrode different from the electrode to which the ground potential is added among the two electrodes of the piezoelectric vibration plate 18, and a potential that is paired with the ground potential is added via a wiring 28.

[0048] Therefore, when an electrical signal is applied via the wiring 28 to the two piezoelectric vibration plates 18a and 18b that are connected face to face with the metal electrode plate 24 interposed therebetween, both will vibrate simultaneously, and compared with the case where there is one piezoelectric vibration plate 18, the generated vibration can be increased. Thereby, even if the piezoelectric vibration plate 18 becomes smaller, since vibrations with increased energy are generated by the two piezoelectric vibration plates 18a and 18b, it is possible to suppress the energy shortage that is a concern when the piezoelectric vibration plate 18 becomes smaller, and it becomes possible to cope with the miniaturization of the vibration sensor 10. Further, if an electrical signal amplified by a power amplifier 70 (see FIG. 7) or the like is used as the electrical signal applied to the vibration excitation sensor 10A, even if the vibration excitation sensor 10A is miniaturized, it is possible to generate vibrations of a size sufficient for the vibrations applied to the object.

[0049] Further, the vibration sensor 10 according to the embodiment of the present invention includes a single piezoelectric vibration plate 18 when used as the vibration receiving sensor 10B as shown in FIGS. 4 to 6. Therefore, the vibration received from the object through the vibration transmission member 12 is transmitted to a single piezoelectric vibration plate 18 physically connected to the vibration transmission member 12, and the electrical signal converted by the piezoelectric vibration plate 18 from the transmitted vibration is taken out through the wiring 28. Then, if the taken-out electrical signal is amplified by, for example, a charge amplifier 76 (see FIG. 7), even if the vibration receiving sensor 10B is miniaturized, in combination with the noise countermeasure of adding a ground potential to the vibration transmission member 12, an electrical signal of a sufficient size for analysis can be obtained. Therefore, it is possible to eliminate the insufficient sensitivity that is a concern when the piezoelectric vibration plate 18 becomes small.

Description of Reference Numerals

[0050] 10: Vibration sensor, 10A: Vibration excitation sensor, 10B: Vibration receiving sensor, 12: Vibration transmission member, 14: Tip portion, 18(18a, 18b): Piezoelectric vibration plate, 24: Metal electrode plate, 28: Wiring, 32: Case body, 36: Protrusion hole, 36a: Edge portion, 40a: Sliding surface, 52: Spring, 54: First damper member, 56: Second damper member

Claims

Claim 1 A vibration sensor for applying vibration to an object or receiving vibration from the object, comprising: a vibration transmission member having a tip portion that abuts against the object; a piezoelectric vibration plate connected to a wiring for applying or extracting an electrical signal; a case body that houses the vibration transmission member and the piezoelectric vibration plate therein and has a protruding hole through which the tip portion protrudes; The vibration sensor is characterized in that the vibration transmission member and the piezoelectric vibration plate are electrically and physically connected, and the vibration transmission member is set to a ground potential. Claim 2 The vibration sensor according to claim 1, wherein the vibration transmission member and the piezoelectric vibration plate are slidably accommodated inside the case body in a direction parallel to the protruding direction of the tip portion, and are biased by a spring in the protruding direction. Claim 3 The vibration sensor according to claim 2, wherein a first damper member is interposed between the vibration transmission member and the piezoelectric vibration plate and a sliding surface inside the case body. Claim 4 The vibration sensor according to claim 2 or 3, wherein a second damper member is disposed between an edge portion of the protruding hole on the inner side of the case body and the vibration transmission member. Claim 5 Including two piezoelectric vibration plates, the two piezoelectric vibration plates are electrically and physically connected face to face with a metal electrode plate interposed therebetween, An electrical signal is applied to the two piezoelectric vibration plates via the wiring, and the vibration sensor is used as a vibration exciter for applying vibration to the object via the vibration transmission member. The vibration sensor according to any one of claims 1 to 4, characterized in that Claim 6 Including one piezoelectric vibration plate, The vibration sensor according to any one of claims 1 to 4, characterized in that it is used as a vibration receiving sensor that receives vibration from the object via the vibration transmission member and extracts an electrical signal from the one piezoelectric vibration plate via the wiring.

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