Sensor Unit

Abstract

To provide a sensor unit with high detection sensitivity.SOLUTION: A sensor unit of the present invention comprises a linear sensor 2, a support body 3 comprising a rigid member 31 having higher rigidity than the linear sensor 2, and a protective member 4 sandwiching the linear sensor 2 with the support body 3. The support body 3 comprises an elastic material 32 attached to a surface of the rigid member 31. The linear sensor 2 is circled on one surface of the support body 3 and is attached to the elastic material 32.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a sensor unit including a linear sensor. [Background technology]

[0002] A linear sensor is known that uses an internal conductor, a piezoelectric body provided in contact with the outer peripheral surface of the internal conductor, and an external conductor provided in contact with the outer peripheral surface of the piezoelectric body as a sensor wire (see, for example, Patent Document 1, etc.). This linear sensor has a characteristic that the piezoelectric body is deformed by the application of an external load, and a voltage is induced between the internal conductor and the external conductor. Using this characteristic, it is being considered to use the linear sensor as a pressure sensor for detecting pressure or a vibration sensor for detecting vibration. It is also being considered to configure a linear sensor using a resistance wire such as conductive rubber or a capacitor wire as a sensor wire instead of a sensor wire using a piezoelectric body. Meanwhile, in recent years, there is a demand for a technology that collects and analyzes state information such as vibrations propagating through the main body or components of a machine tool, etc., to predict deterioration of consumable parts such as tools used in the machine tool, etc., and failures of the machine tool in advance, and to develop a maintenance plan for more efficient part replacement. It is also being considered to collect and analyze vibration data propagated in a similar manner in devices such as robots, agricultural machines, cars, and home appliances, to predict failures and improve work efficiency. Hereinafter, devices such as machine tools, robots, agricultural machines, cars, and home appliances, as well as components of these devices, are collectively referred to as the object to be detected. Furthermore, it has been considered to use a linear sensor attached to the object to be detected with fixing tape as a sensor for detecting the motion of the object to be detected (for example, see Patent Document 2, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2019 / 117037 [Patent Document 2] Patent Publication 2019-209450 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the linear sensor is attached with a fixing tape, the pressing force of the linear sensor against the object to be detected is not increased so much, so there is a problem that the transmission rate of the vibration generated by the object to directly vibrate the linear sensor is low. In addition, if the linear sensor is fixed with fixing devices such as screws or clips to increase the pressing force, multiple fixing devices are required along the length of the linear sensor. Moreover, the variation in the fastening force of each fixing device directly occurs as a variation in the pressing force of the linear sensor. Furthermore, the part of the linear sensor that is away from the fixing devices does not receive the pressing force against the object to be detected, so the vibration of the object to be detected is hardly detectable in that part. As a result, there is a problem that the detection sensitivity of the linear sensor as a whole is reduced.

[0005] In view of the above circumstances, an object of the present invention is to provide a sensor unit with high detection sensitivity. [Means for solving the problem]

[0006] The sensor unit of the present invention that achieves the above object comprises: A linear sensor; A support having a rigid member having a rigidity higher than that of the linear sensor; a terminal member to which an end of the linear sensor is connected, the linear sensor is attached to the support; The terminal member is characterized in that it is disposed on the surface of the support opposite to the surface on which the linear sensor is attached, between the support and a conductive shield member. In addition, the sensor unit of the present invention that achieves the above object comprises a linear sensor, A support having a rigid member having a rigidity higher than that of the linear sensor; a terminal member to which an end of the linear sensor is connected, the linear sensor is attached to the support; The support has a conductor, The terminal member is characterized in that it is disposed on the surface of the support opposite to the surface on which the linear sensor is attached, between the conductor and the conductive shielding member. Also, A linear sensor; a support having a rigid member having a rigidity higher than that of the linear sensor, The linear sensor is attached to the support. May .

[0007] By installing the sensor unit of the present invention so that the linear sensor is located between the support and the object to be detected, and pressing the support against the object to be detected, the linear sensor can be pressed against the object to be detected with a uniform pressing force over its entire length, which makes it possible to detect vibration waves propagating through the object to be detected with high sensitivity.

[0008] Here, the rigid member may be a plate-like member or a curved plate-like member, and may be made of metal, resin, rubber, or other elastic material, and the support may be disk-like, rectangular, or even cylindrical or semi-cylindrical.

[0009] In the sensor unit of the present invention, the support member is a member having an elastic body attached to a surface of the rigid member, The linear sensor may be attached to the elastic body.

[0010] Since the linear sensor is attached to the elastic body, the pressing force pressing the linear sensor against the object to be detected is made more uniform over the entire length of the linear sensor. Furthermore, even if the support body is pressed against the object to be detected more strongly than necessary, the elastic body deforms and the pressing force is alleviated, so that the load applied to the linear sensor can be suppressed.

[0011] In addition, in the sensor unit of the present invention, the linear sensors may be arranged in a star shape, wave shape, or zigzag shape on one surface of the support, or may be arranged in a circular pattern on one surface of the support.

[0012] By arranging the linear sensors in a circumferential manner, vibration waves propagating from any direction along the surface of the one surface can be detected with high sensitivity.

[0013] Here, the linear sensor may be arranged in a spiral shape with a plurality of turns.

[0014] In the sensor unit of the present invention, the support may have a through hole.

[0015] By utilizing the through holes, the sensor unit can be easily fixed to the object to be detected with fasteners such as screws.

[0016] In the sensor unit of the present invention, the through hole may pass through the support at a center of gravity.

[0017] This makes it possible to make the pressing force that presses the linear sensor against the object to be detected more uniform over the entire length of the linear sensor.

[0018] Here, a magnet may be placed in the through hole of the support, and the magnetic force of the magnet may be used to fix the support to the surface of the object to be detected, such as a machine. Furthermore, a cap made of a ferromagnetic material or a soft magnetic material may be provided to cover the entire support except for the surface on which the linear sensor is disposed, and the magnetic force of the cap may be used to fix the sensor unit to the surface of the object to be detected. With this configuration, the support can be attached even more strongly to the surface of the object to be detected.

[0019] The sensor unit of the present invention may further include a protection member that sandwiches the linear sensor between the support and the protection member.

[0020] Since the linear sensor is covered by the support body and the protective member, the linear sensor can be prevented from being worn down.

[0021] Here, the protective member may be in the form of a thin plate. If it is in the form of a thin plate, the thickness is preferably 0.1 mm or more and 1.0 mm or less. The protective member may be made of metal or resin. Furthermore, the protective member may be a metal foil.

[0022] In the sensor unit of the present invention, the support has a groove formed therein, The linear sensor may be disposed in the groove.

[0023] In this way, the linear sensor of a certain length can be attached to a predetermined position of the support body. Also, since a radial part of the linear sensor protrudes from the groove, the linear sensor can be sandwiched between the support body and the object to be detected. As a result, vibration waves and the like can be detected stably with high sensitivity.

[0024] Here, the groove may be shallower than the diameter of the linear sensor. The groove may be a long groove. Furthermore, the groove may be arranged in a wave shape or a zigzag shape on one surface of the support, or may be formed in a circumferential manner on one surface of the support.

[0025] Furthermore, the sensor unit of the present invention further comprises a terminal member to which an end of the linear sensor is connected, The terminal member may be disposed on a surface of the support opposite to a surface on which the linear sensor is attached.

[0026] When this sensor unit is installed so that the linear sensor is positioned between the support and the detectable object, the terminal member is not present between the support and the detectable object, so that when the support is pressed toward the detectable object, the linear sensor can be pressed against the detectable object with a more uniform pressing force over its entire length.

[0027] Here, the terminal member may have a thickness greater than a diameter of the linear sensor.

[0028] Furthermore, in the sensor unit of the present invention, the support has a conductor, The terminal member may be disposed between the conductor and a conductive shield member.

[0029] By disposing the terminal member between the conductor and the conductive shield, it is possible to prevent noise from entering the terminal member.

[0030] The sensor unit of the present invention may further include an amplifier that amplifies an output signal from the linear sensor.

[0031] By providing the amplifier, the signal-to-noise ratio of the output signal can be increased.

[0032] Here, the amplifier may be disposed on the terminal member, and the terminal member may be a printed circuit board on which the amplifier is mounted. Effect of the Invention

[0033] According to the present invention, a sensor unit with high detection sensitivity can be provided. [Brief description of the drawings]

[0034] [Figure 1] FIG. 2A is a cross-sectional view showing the structure of a linear sensor of the present embodiment, and FIG. 2B is a view showing the structure of an end portion and a terminal member of the linear sensor. [Diagram 2] FIG. 2A is a plan view of the sensor unit of the present embodiment, and FIG. 2B is a front view of the sensor unit shown in FIG. [Diagram 3] 3 is a bottom view showing a state in which a protective member is removed from the sensor unit shown in FIG. 2. [Figure 4] 3A is an attachment diagram showing an example of a state in which the sensor unit shown in FIG. 2 is attached to a detectable object by a fixing device, and FIG. 3B is an attachment diagram showing an example of a state in which the sensor unit is attached to a detectable object by an adhesive member. [Diagram 5]FIG. 13A is a front view of a sensor unit according to a second embodiment, and FIG. 13B is a bottom view showing a state in which a protective member has been removed from the sensor unit shown in FIG. [Figure 6] FIG. 13A is a plan view of a sensor unit according to a third embodiment, and FIG. 13B is a front view of the sensor unit shown in FIG. [Figure 7] 7(a) is a plan view showing the sensor unit shown in FIG. 6 with the conductive shielding member removed, and (b) is a bottom view showing the sensor unit shown in FIG. 6 with the protective member removed. [Figure 8] FIG. 7(b) is a cross-sectional view taken along line AA of FIG. [Figure 9] FIG. 13A is a plan view of a sensor unit according to a fourth embodiment, and FIG. 13B is a front view of the sensor unit shown in FIG. [Figure 10] FIG. 10 is an exploded perspective view of the sensor unit shown in FIG. [Figure 11] 10A is a bottom view showing the sensor unit shown in FIG. 9 with a protective member removed, and FIG. 10B is a cross-sectional view taken along line BB of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a linear sensor used in a sensor unit of the present embodiment will be described.

[0036] Fig. 1(a) is a cross-sectional view showing the structure of the linear sensor of this embodiment, and Fig. 1(b) is a diagram showing the structure of the end of the linear sensor and the terminal member. In Fig. 1(b), the size of the linear sensor 2 is exaggerated relative to the terminal member 27 in order to make the shape of the linear sensor 2 easier to understand. In Fig. 1(b), the linear sensor 2 is simplified to a single solid line except for both end portions, and the simplified portion is shown short.

[0037] As shown in Figures 1(a) and 1(b), the linear sensor 2 includes a sensor wire 20, an inner sheath 24, a shield coating 25, and an outer sheath 26. The sensor wire 20 is composed of an internal conductor 21, a piezoelectric body 22, and an external conductor 23. As shown in Figure 1(a), the internal conductor 21 is disposed at the center of the linear sensor 2, and is composed of seven conductor wires 211. The piezoelectric body 22 is provided on the outer periphery of the internal conductor 21. The external conductor 23 is provided on the outer periphery of the piezoelectric body 22.

[0038] All of the seven conductor wires 211 have a diameter of 10 μm, of which four are stainless steel conductor wires 211S and the remaining three are copper conductor wires 211C. In FIG. 1(a), the stainless steel conductor wires 211S are hatched downward to the left, and the copper conductor wires 211C are hatched downward to the right. In the internal conductor 21 shown in FIG. 1(a), the conductor wire arranged at the center is a stainless steel conductor wire 211S (stainless steel wire), and the conductor wires arranged on the periphery are alternately made of stainless steel conductor wires 211S and copper conductor wires 211C. The copper conductor wire 211C has a lower electrical resistance and is softer than the stainless steel conductor wire 211S. Conversely, the stainless steel conductor wire 211S has a higher electrical resistance than the copper conductor wire 211C, but has higher mechanical strength (e.g., tensile strength) and rigidity.

[0039] The seven conductor wires 211 are arranged at the vertices of a regular hexagon and at the center of the regular hexagon. These seven conductor wires 211 are twisted together. That is, the internal conductor 21 is formed by twisting the seven conductor wires 211 together after arranging them in a close-packed structure in the cross section. In this case, the thickness of the internal conductor 21 is a maximum of 30 μm. By twisting the multiple conductor wires 211 in this manner with a loose twist or a medium twist, loosening in the direction opposite to the twisting direction is permitted, and flexibility can be imparted to the linear sensor 2.

[0040] The diameter of the conductor wire 211 is not limited to 10 μm, and may be 8 μm to 40 μm, and is preferably 8 μm to 30 μm. The thinner the conductor wire 211, the higher the flexibility but the lower the strength and rigidity, and the thicker the conductor wire 211, the lower the flexibility but the higher the strength and rigidity. If the thickness of the conductor wire 211 is 20 μm or more, it can be manufactured at low cost and easily. The inner conductor 21 may be formed by twisting together conductor wires 211 of different thicknesses.

[0041] Although the internal conductor 21 shown in FIG. 1(a) is made by twisting seven conductor wires 211, the number of wires does not have to be seven. By twisting a plurality of conductor wires 211 together, the flexibility of the linear sensor 2 can be increased. Also, for example, a plurality of bundles of twisted wires may be prepared, and these may be further twisted together. For example, seven bundles of twisted seven thin conductor wires 211 may be prepared, and the bundles may be further twisted together. By twisting in a plurality of stages, the flexibility of the linear sensor 2 is further increased, so that the linear sensor 2 is easily deformed in response to vibrations or the like applied to the linear sensor 2. As a result, the detection sensitivity of the linear sensor 2 can be increased. When the twisting process is performed multiple times, such as when twisting in a plurality of stages, the twisting directions may be different. On the other hand, a plurality of conductor wires 211 may be bundled in a straight line without being twisted together. Furthermore, these configurations may be combined, for example, by twisting together a bundle of multiple untwisted conductor wires 211 and multiple twisted conductor wires 211. Even in these cases, the multiple conductor wires 211 can be bonded and bundled together by applying a piezoelectric material, thereby producing a single piezoelectric fiber.

[0042] In the sensor wire 20 described above, a plurality of types of conductor wires having different mechanical strengths and electrical resistances are used as the conductor wires 211 constituting the internal conductor 21. However, when the flexibility is to be further increased or the electrical resistance is to be further decreased, the central conductor wire 211 may be replaced with the copper conductor wire 211C, or all of the seven conductor wires 211 may be made of copper conductor wires 211C. Conversely, when the mechanical strength and rigidity are to be further increased, all of the seven conductor wires 211 may be made of stainless steel conductor wires 211S. In addition, instead of the stainless steel conductor wire 211S, a conductor wire made of tungsten, or a conductor wire made of high tensile steel or ultra-high tensile steel such as tungsten and its alloy may be used, and instead of the copper conductor wire 211C, a conductor wire made of titanium, a titanium alloy, or a conductor wire made of magnesium or magnesium alloy may be used. Furthermore, the conductor wire may be a conductor wire containing carbon nanotubes, or a conductor wire containing pitch-based carbon fibers. Alternatively, a conductor wire made of spring steel that is easily elastically deformed may be used.

[0043] The piezoelectric body 22 is formed by applying a piezoelectric material such as polyvinylidene fluoride (PVDF) to the internal conductor 21. Polyvinylidene fluoride is a lightweight polymeric material that generates a piezoelectric effect, and has the property that a voltage is generated when pressure is applied to it, and a distortion occurs when a voltage is applied to it. The piezoelectric body 22 has been subjected to a polarization process, and a voltage is induced between the internal conductor 21 and the external conductor 23 when the piezoelectric body 22 is deformed by vibration or the like.

[0044] 1(a) may be exemplified by the piezoelectric material constituting the piezoelectric body 22, such as polyvinylidene fluoride, trifluoroethylene (TrEF), a mixed crystal material of PVDF and TrEF, and a polymeric material having a dipole moment, such as polylactic acid, polyuric acid, and polyamino acid. The method of applying the piezoelectric material may be immersion (dip) coating, spray coating, brush coating, or application by a coating device such as a coater. The method is not limited to a coating configuration, and may be, for example, a configuration in which a strip-shaped PVDF film is spirally wound around the internal conductor 21.

[0045] The thickness of the piezoelectric body 22 is preferably equal to or greater than the diameter of the conductor wire 211. The thickness of the piezoelectric body 22 shown in FIG. 1(a) is 10 μm at its thinnest point, but is preferably 10 μm to 50 μm. The thicker the piezoelectric body 22 is, the better the detection sensitivity becomes, but the limit value of the thickness of the piezoelectric body 22 is determined by the viscosity of the applied piezoelectric material and the application method. In addition, if the thickness of the piezoelectric body 22 is too thick, there is a disadvantage that the linear sensor 2 becomes too hard and lacks flexibility.

[0046] In the internal conductor 21 shown in Fig. 1(a), multiple conductor wires 211 are twisted together, and therefore there are depressions at the boundaries between the conductor wires 211. These depressions can support more piezoelectric material, and the volume of the piezoelectric material is larger (thicker), resulting in better detection sensitivity than other parts. Due to these depressions, the internal conductor 21 has six parts where the piezoelectric material is thicker than other parts, evenly spaced in the circumferential direction, which is why it functions as a highly sensitive piezoelectric fiber no matter what direction it is bent.

[0047] In addition, the adjacent conductor wires 211 shown in FIG. 1(a) are almost in contact with each other, but the piezoelectric material permeates through a small gap by capillary action, and the gap between the adjacent conductor wires 211 (inside the internal conductor 21) is filled with the piezoelectric material. However, depending on the viscosity of the piezoelectric material and the application method, the piezoelectric material may not permeate the gap between the adjacent conductor wires 211. Even in this case, it is sufficient that the piezoelectric material is supported on the portion facing the outer periphery of the internal conductor 21. In the configuration in which the strip-shaped PVDF film described above is used as the piezoelectric body 22, the linear sensor 2 is one in which the piezoelectric material does not permeate the gap between the adjacent conductor wires 211. In this linear sensor 2, the flexibility of the linear sensor 2 is increased compared to that in which the piezoelectric material permeates the gap between the adjacent conductor wires 211, and the detection sensitivity of the linear sensor 2 is increased.

[0048] The external conductor 23 shown in FIG. 1(a) is formed by applying a polymer conductive material containing carbon such as carbon nanotubes to the outer periphery of the piezoelectric body 22. The conductive material forming the external conductor 23 may be a polymer conductive material containing silver particles, silver paste, or the like. The conductive material may be applied by immersion (dip) coating, spray coating by a spray or the like, brush coating, or coating by a coating device such as a coater. The thickness of the external conductor 23 is preferably equal to or less than the diameter of the conductor wire 211, and is also preferably equal to or less than the thickness of the piezoelectric body 22. The thickness of the external conductor 23 shown in FIG. 1(a) is 5 μm, but is preferably 5 μm or more and 50 μm or less. The external conductor 23 may be a conductor wire without using a conductive material.

[0049] The inner sheath 24 covers the outer periphery of the outer conductor 23 to improve abrasion resistance, chemical resistance, and rust resistance. The inner sheath 24 is formed to a thickness of 6 μm. The inner sheath 24 is made of a material that is softer than the outer sheath 26. The inner sheath 24 is formed by applying a polyamide synthetic resin, but may also be formed by applying a polyvinyl chloride resin.

[0050] The shield coating 25 is a shield formed by braiding thin metal wires such as nickel-plated copper or stainless steel into a tube shape. The shield coating 25 may be formed by depositing copper, aluminum, or the like on the inner sheath 24 having the inner conductor 21, the piezoelectric body 22, and the outer conductor 23 on the inside. The shield coating 25 may be attached to the inner sheath 24 by other methods such as sputtering, EBD (electron beam deposition), CVD (chemical vapor deposition), coating, dipping (dipping), electroless plating, or bonding with an adhesive, or may be formed by wrapping a metal foil around it.

[0051] The outer sheath 26 is made of a material having higher abrasion resistance than the inner sheath 24. The outer sheath 26 is formed by coating with polytetrafluoroethylene (PTFE). However, the outer sheath 26 may be formed by coating with tetrafluoro-hexafluoropropylene fluororesin (FEP), tetrafluoroethylene ethylene copolymer (EPFE), or tetrafluoroethylene perfluoroalkoxyethylene copolymer fluororesin (PFA). The coating here may be immersion (dip) coating, spray coating, brush coating, or coating with a coating device such as a coater. In addition, it is preferable to apply multiple times in consideration of the occurrence of pinholes. In addition, the outer sheath 26 may be thicker than the inner sheath 24. Furthermore, the inner sheath 24 may be formed of a flammable material, but the outer sheath 26 is preferably formed of a flame-retardant material, a non-flammable material, or a flame-resistant material.

[0052] The diameter of the linear sensor 2 shown in Fig. 1(a) is 0.1 mm. However, the diameter of the linear sensor 2 may be larger or smaller, and is preferably 0.1 to 3.0 mm. In this specification, the symbol "to" indicating a numerical range includes the upper and lower limits.

[0053] As shown in FIG. 1B, the linear sensor 2 is formed in a loop shape. Both ends of the linear sensor 2 are connected to a terminal member 27. The terminal member 27 is a so-called flexible printed wiring board in the form of a film that is folded in half so as to sandwich both ends of the linear sensor 2 and overlap each other. Both ends of the linear sensor 2 are fixed to the terminal member 27 by being sandwiched between the terminal member 27. The terminal member 27 is formed with a first wiring pattern 271, a second wiring pattern 272, and a third wiring pattern 273, which are simplified and shown by thick dashed lines in FIG. 1B. In addition, a shield layer (not shown) for preventing the intrusion of noise is formed on the front side of the terminal member 27, and the first wiring pattern 271, the second wiring pattern 272, the third wiring pattern 273, and both ends of the linear sensor 2 are covered by the shield layer.

[0054] At both ends of the linear sensor 2, the outer sheath 26, the shield coating 25, the inner sheath 24, the outer conductor 23, and the piezoelectric body 22 are peeled off in a stepped manner in this order, so that the inner conductor 21, the piezoelectric body 22, the outer conductor 23, the inner sheath 24, and the shield coating 25 are each exposed by about 1 to 3 mm in the extension direction of the linear sensor 2. The inner conductor 21 exposed at one end of the linear sensor 2 (the end of the linear sensor 2 drawn on the upper side in FIG. 1(b), the same below) is connected to the first wiring pattern 271 by soldering, and is electrically connected to the inner conductor 21 exposed at the other end of the linear sensor 2 (the end of the linear sensor 2 drawn on the lower side in FIG. 1(b), the same below) by a first lead wire 21L. Moreover, the external conductor 23 exposed at one end of the linear sensor 2 is connected to the second wiring pattern 272 by soldering, and is electrically connected by a second lead wire 23L to the external conductor 23 exposed at the other end of the linear sensor 2. Furthermore, the shield coating 25 exposed at one end of the linear sensor 2 is connected to the third wiring pattern 273 by soldering, and is electrically connected by a third lead wire 25L to the shield coating 25 exposed at the other end of the linear sensor 2. The first lead wire 21L, the second lead wire 23L, and the third lead wire 25L are indicated by two-dot chain lines in FIG. 1(b).

[0055] A signal cable 28 is connected to the terminal member 27. A signal line, a signal ground line, and a ground line are provided in the signal cable 28. The first wiring pattern 271 is connected to the signal line in the signal cable 28, the second wiring pattern 272 is connected to the signal ground line in the signal cable 28, and the third wiring pattern 273 is connected to the ground line in the signal cable 28. The signal cable 28 is for transmitting a signal obtained by the linear sensor 2 to a measuring device or a circuit board (not shown). The linear sensor 2, the terminal member 27, and the signal cable 28 constitute a linear sensor assembly.

[0056] FIG. 2(a) is a plan view of the sensor unit of this embodiment, and FIG. 2(b) is a front view of the sensor unit shown in FIG. 2(a).

[0057] As shown in FIG. 2(a) and FIG. 2(b), the sensor unit 1 includes a linear sensor assembly including the linear sensor 2, the terminal member 27, and the signal cable 28, a support member 3, and a protective member 4. The support member 3 is disk-shaped with a support through-hole 3a. The support member 3 includes a rigid member 31 and an elastic body 32. The rigid member 31 is a plate-shaped member made of stainless steel and has a thickness of 1.6 mm. The rigid member 31 may be made of other metals such as aluminum or brass, or may be made of resin such as engineering plastic, or may be made of ceramic, as long as it has a higher rigidity than the linear sensor 2. When the rigid member 31 is made of a conductive material such as a metal, the rigid member 31 corresponds to an example of a conductor. The rigid member 31 preferably has a uniform thickness of 0.3 mm to 5.0 mm.

[0058] The elastic body 32 is a sheet-like body made of synthetic rubber. The elastic body 32 is attached to the rigid member 31 with an adhesive. However, the elastic body 32 may be made of natural rubber or a resin foam. The elastic body 32 may be attached to the rigid member 31 with something other than an adhesive, such as double-sided tape.

[0059] Support through hole 3a penetrates the center of support 3 in the thickness direction of support 3 (the direction perpendicular to the paper surface in FIG. 2(a)). That is, support through hole 3a penetrates the center of each of rigid member 31 and elastic body 32. Since rigid member 31 and elastic body 32 constituting support 3 are configured to have a uniform thickness overall, center of gravity position 3c of support 3 is at the center of support 3. Therefore, support through hole 3a penetrates center of gravity position 3c of support 3.

[0060] The linear sensor 2 is attached with an adhesive to one surface of the elastic body 32 opposite to the surface attached to the rigid member 31. A part of the terminal member 27 is also attached with an adhesive to one surface of the elastic body 32, similar to the linear sensor 2. However, the linear sensor 2 and a part of the terminal member 27 may be attached to the elastic body 32 with double-sided tape or the like.

[0061] The protective member 4 is disk-shaped with a protective member through hole 4a in the center, similar to the support 3. The protective member 4 is made of a thin aluminum plate with a thickness of 0.3 mm. However, the protective member 4 may be made of other metal thin plates such as stainless steel, or a resin film. The thickness of the protective member 4 is preferably 0.1 mm or more and 1.0 mm or less. The protective member 4 is attached to the linear sensor 2 and the elastic body 32 with an adhesive. However, the protective member 4 may be attached to the linear sensor 2 and the elastic body 32 with double-sided tape or the like. The protective member 4 may be attached to only one of the linear sensor 2 and the elastic body 32. The linear sensor 2 is covered by being sandwiched between the support 3 and the protective member 4, and wear is prevented.

[0062] Fig. 3 is a bottom view showing a state in which a protective member is removed from the sensor unit shown in Fig. 2. In Fig. 3, the linear sensor 2 is indicated by a thick solid line.

[0063] As shown in FIG. 3, the linear sensor 2 is attached to one surface of the elastic body 32 while avoiding the support through hole 3a. In FIG. 3, the linear sensor 2 is arranged in a spiral shape with about 1.5 revolutions, but the number of revolutions may be one or more revolutions. By arranging the linear sensor 2 in a spiral shape, vibration waves propagating from any direction in the surface direction of the support 3 can be detected with high sensitivity. In addition, in this embodiment, the terminal member 27 is also attached to one surface of the elastic body 32 while avoiding the support through hole 3a. As described above, the terminal member 27 is a film-like member with a thin thickness, so that even if it is sandwiched between the support 3 and the protective member 4 (see FIG. 2(b)), the gap between the support 3 and the protective member 4 does not widen significantly. Note that the linear sensor 2 may be formed longer than that shown in FIG. 3, and the linear sensor 2 may be pulled out from between the support 3 and the protective member 4 to connect the linear sensor 2 to the terminal member 27 at a position away from the support 3 and the protective member 4. However, such a connection makes it easier for the linear sensor 2 to be cut at the edges of the support 3 and the protective member 4, so it is preferable to fix the terminal member 27 to the support 3 as in this embodiment.

[0064] FIG. 4(a) is a mounting state diagram showing an example of a state in which the sensor unit shown in FIG. 2 is mounted on a detection target by a fastener.

[0065] As shown in FIG. 4, a screw hole 9a is provided at a measurement location of the object to be detected 9. The sensor unit 1 is fixed to the object to be detected 9 by a washer screw 81 having a screw portion passing through the support through hole 3a of the support 3 and the protective member through hole 4a of the protective member 4. The presence of the support through hole 3a of the support 3 and the protective member through hole 4a of the protective member 4 allows the sensor unit 1 to be easily fixed to the object to be detected 9 by a screw or the like. The sensor unit 1 is pressed against the object to be detected 9 by the washer screw 81. In other words, a pressed portion is formed on the surface of the support 3 opposite to the surface on which the linear sensor 2 is arranged, and the pressed portion is pressed by the seat 81a of the washer screw 81, so that the sensor unit 1 is pressed against the object to be detected 9 and fixed. Note that a screw with a washer may be used instead of the washer screw 81.

[0066] In this mounting state, when the entire object to be detected 9 moves, the linear sensor 2 also moves with the object to be detected 9, so that the linear sensor 2 is hardly affected by the movement. In other words, the detection sensitivity to the movement of the entire object to be detected 9 and the vibration of the entire object to be detected 9 is low. On the other hand, when the vibration wave traveling on the surface of the object to be detected 9 reaches the sensor unit 1, the linear sensor 2 is subjected to a load due to the wave in accordance with the wave period, but since the support 3 prevents the linear sensor 2 from moving away from the object to be detected 9, the linear sensor 2 deforms in response to the vibration wave and a voltage is induced. In addition, the linear sensor 2 is pressed uniformly against the object to be detected 9 by the rigid member 31, with the pressing force of the washer screw 81 being evenly applied to the entire length of the linear sensor 2, so that the linear sensor 2 can detect the vibration wave with the entire linear sensor 2. As a result, the sensor unit 1 in the mounting state shown in FIG. 4(a) can detect the vibration wave traveling on the surface of the object to be detected 9 with high sensitivity. It should be noted that the same effect can be obtained by using other fasteners such as clips instead of screws such as the washer screws 81 to press and fasten the sensor unit 1 against the detection object 9.

[0067] Even if the washer screw 81 is overtightened, the elastic body 32 reduces the load applied to the linear sensor 2, thereby preventing the load for fixing the sensor unit 1 to the object to be detected 9 from being applied more than necessary to the linear sensor 2. In addition, the provision of the elastic body 32 makes it easier to make the load for fixing the sensor unit 1 to the object to be detected 9 more uniform over the entire length of the linear sensor 2.

[0068] FIG. 4(b) is an attachment diagram showing an example of a state in which the sensor unit is attached to the detection object by an adhesive member.

[0069] As shown in FIG. 4(b), the sensor unit 1 is fixed to the object to be detected 9 by a double-sided tape 82. An adhesive or a pressure-sensitive adhesive may be used instead of the double-sided tape 82. These double-sided tapes, adhesives, and pressure-sensitive adhesives are examples of adhesive materials. When the sensor unit 1 is fixed to the object to be detected 9 by an adhesive material such as the double-sided tape 82, the linear sensor 2 is not pressed against the object to be detected 9, so that the linear sensor 2 is less susceptible to the influence of vibration waves traveling along the surface of the object to be detected 9. In other words, the detection sensitivity to vibration waves generated on the surface of the object to be detected 9 is low. On the other hand, the load applied to the sensor unit 1 from the outside of the object to be detected 9 (the upper side in FIG. 4(b)) can be detected with high sensitivity. In addition, even if a load is applied to a very small area of ​​the outer surface of the sensor unit 1, the entire support 3 applies the load to the linear sensor 2, so that a large voltage is induced in the entire linear sensor 2, and as a result, the pressure can be detected with high sensitivity. Furthermore, if the surface on which the sensor unit 1 is installed is horizontal and the object to be detected 9 does not move or vibrate, the sensor unit 1 can be simply placed without being fixed, and can detect external loads with high sensitivity, just as in this mounted state.

[0070] According to the sensor unit 1 described above, it is possible to detect the vibration wave traveling on the surface of the detection object 9 or the load applied to the sensor unit 1 with high sensitivity.

[0071] Next, a sensor unit 1 according to a second embodiment will be described. In the following description, components having the same names as components described so far will be denoted by the same reference numerals used so far, and duplicate descriptions may be omitted.

[0072] FIG. 5(a) is a front view of a sensor unit according to the second embodiment, and FIG. 5(b) is a bottom view showing a state in which a protective member has been removed from the sensor unit shown in FIG. 5(a).

[0073] The sensor unit 1 shown in Fig. 5(a) and Fig. 5(b) has a different arrangement of the terminal member 27 from the sensor unit 1 of the previous embodiment. The terminal member 27 is attached to the surface of the support 3 opposite to the surface to which the protective member 4 is attached. Hereinafter, the surface side to which the protective member 4 is attached (the lower side in Fig. 5(a)) may be referred to as the inside, and the opposite side (the upper side in Fig. 5(a)) may be referred to as the outside. As shown in Fig. 5(b), the support 3 is provided with an extraction hole 3b. The extraction hole 3b penetrates the support 3 in the thickness direction (the direction perpendicular to the paper surface in Fig. 5(b)) near the periphery of the support 3. That is, the extraction hole 3b penetrates the rigid member 31 and the elastic body 32 near their respective peripheries. The portions 2b near both ends of the linear sensor 2 extend from the inner surface to the outer surface of the support 3 through the extraction hole 3b. Both ends of the linear sensor 2 are connected to terminal members 27 attached to the outer surface of the support 3, as shown in FIG. 5(a).

[0074] The terminal member 27 has a thickness slightly thicker than the diameter of the linear sensor 2 because the linear sensor 2 is sandwiched therein. For this reason, in the configuration of the previous embodiment, the portion of the linear sensor 2 in the vicinity of the terminal member 27 may not easily transmit vibrations occurring in the detection target 9 (see FIG. 4) or loads applied to the sensor unit 1. In contrast, in the sensor unit 1 of the second embodiment, in a mounting state in which the sensor unit 1 is mounted on the detection target 9 so that the linear sensor 2 is located between the support 3 and the detection target 9 (see FIG. 4), the terminal member 27 is disposed on the outer surface of the support 3 without being sandwiched between the support 3 and the detection target 9. As a result, the portions of the linear sensor 2 disposed on the surface of the support 3 facing the detection target 9 are all disposed facing the detection target 9 under the same conditions.

[0075] In addition to the effects of the previous embodiment, the second embodiment has the effect that when the support 3 is pressed against the object to be detected 9 with a fixing device such as a washer screw 81 (see FIG. 4(a)), the linear sensor 2 can be pressed against the object to be detected 9 with a more uniform pressing force. Furthermore, when the sensor unit 1 is fixed to the object to be detected 9 with an adhesive member such as a double-sided tape 82 (see FIG. 4(b)), even if a load is applied to a very small area of ​​the outer surface of the sensor unit 1, the entire support 3 will be subjected to a similar load on the entire portion of the linear sensor 2 that is disposed on the surface facing the object to be detected 9. Therefore, there is also the effect that the load applied to the sensor unit 1 can be detected with higher sensitivity.

[0076] Next, a sensor unit 1 according to a third embodiment will be described. In the description of the third embodiment, the differences from the sensor unit 1 according to the second embodiment will be mainly described.

[0077] Fig. 6(a) is a plan view of the sensor unit of the third embodiment, and Fig. 6(b) is a front view of the sensor unit shown in Fig. 6(a). Note that in Fig. 6(b), the thicknesses of the protective member 4 and the conductive shielding member 5 are exaggerated relative to the thickness of the rigid member 31.

[0078] The sensor unit 1 of the third embodiment differs from the sensor unit 1 of the second embodiment shown in FIG. 5 mainly in the configuration of the terminal member 27 and the shape of the rigid member 31. The sensor unit 1 of the third embodiment also differs from the sensor unit 1 shown in FIG. 5 in that it includes a conductive shielding member 5. As shown in FIG. 6(a) and FIG. 6(b), the sensor unit 1 includes a linear sensor 2, a terminal member 27, a signal cable 28, a support 3, a protective member 4, and a conductive shielding member 5. The support 3 is mainly composed of a rigid member 31, and an elastic body 32 (see FIG. 8) is disposed at the bottom of a long groove 31b (see FIG. 7) formed in the rigid member 31. The rigid member 31 and the elastic body 32 will be described later. The conductive shielding member 5 is attached to the outer surface of the support 3. The conductive shielding member 5 is made of stainless steel and has a thickness of 0.05 mm to 0.1 mm. The conductive shielding member 5 may be made of other materials such as a metal thin plate or a conductive film other than stainless steel as long as it is conductive. The conductive shield member 5 is disk-shaped with a shield through hole 5a provided in the center, similar to the rigid member 31. The support member through hole 3a, the protective member through hole 4a, and the shield through hole 5a in the third embodiment have the same diameter, and are holes with a larger diameter than the support member through hole 3a of the support member 3 in the second embodiment. This diameter is set appropriately based on the size and shape of the fixture to be used.

[0079] 7(a) is a plan view showing the sensor unit shown in FIG. 6 with the conductive shielding member removed, and FIG. 7(b) is a bottom view showing the sensor unit shown in FIG. 6 with the protective member removed.

[0080] As shown in FIG. 7(a), the terminal member 27 is configured by a printed circuit board on which an amplifier 274 is mounted. The amplifier 274 is for amplifying the output signal of the linear sensor 2 and sending it to the signal cable 28. The amplifier 274 amplifies the signal voltage to about ±5V. In addition, the impedance of the input side of this amplifier, which is the linear sensor 2 side, is high, and the impedance of the output side, which is the signal cable 28 side, is lower than the input side. The impedance of the input side is preferably 10 kΩ or more and 10 MΩ or less. The impedance of the output side is preferably 10 Ω or more and 100 kΩ or less. In this embodiment, the impedance of the input side is set to 1 MΩ, and the impedance of the output side is set to 200 Ω. In this way, the signal input to the amplifier 274 is amplified in both voltage and current and output from the amplifier 274. In addition to the signal line, the signal ground line, and the earth line, a power line for the amplifier 274 is also provided in the signal cable 28 of the third embodiment.

[0081] A terminal groove 31a is formed on the outer surface of the rigid member 31, into which the terminal member 27 and one end portion of the signal cable 28 are embedded. This terminal groove 31a is continuous with the lead-out hole 3b. The linear sensor 2 has both end portions passing through this lead-out hole 3b. Both end portions of the linear sensor 2 are connected to the terminal member 27. The terminal groove 31a has a cable guide portion 31c extending to the outer peripheral end of the rigid member 31. The one end portion of the signal cable 28 and the terminal member 27 are embedded in the terminal groove 31a formed on the outer surface of the rigid member 31, and are located inside the surface of the rigid member 31 to which the conductive shield member 5 (see FIG. 6) is attached. As described above, the rigid member 31 and the conductive shield member 5 are made of stainless steel having conductivity. The terminal member 27 is disposed between the rigid member 31 and the conductive shield member 5, so that the terminal member 27 is electrically shielded, and the intrusion of noise into the terminal member 27 is suppressed. Furthermore, since the terminal members 27 are also physically shielded, damage to the terminal members 27 is also suppressed.

[0082] As shown in FIG. 7(b), a long groove 31b is formed on the inner surface of the rigid member 31. In FIG. 7(b), the long groove 31b is formed in a spiral shape with approximately two revolutions. However, the number of revolutions of the long groove 31b may be one or more than two. The linear sensor 2 is disposed in the long groove 31b. The middle portion 2a of the linear sensor 2 is folded back by going around the side of a small pillar 311 formed at the end of the long groove 31b. The linear sensor 2 is covered with a tube 29 except for the middle portion 2a and the portions 2b near both ends. Although the tube 29 may be omitted, providing the tube 29 makes it easier to dispose the linear sensor 2 in the long groove 31b by integrating the forward line of the linear sensor 2 and the return line of the linear sensor 2 into one.

[0083] FIG. 8 is a cross-sectional view taken along line AA in FIG.

[0084] As shown in FIG. 8, an elastic body 32 is disposed at the bottom of the long groove 31b. That is, the bottom surface of the long groove 31b is formed by the elastic body 32. As a result, the bottom surface of the long groove 31b is higher by the thickness of the elastic body 32. The depth h1 of the long groove 31b is uniform over the entire length. In addition, since the depth h1 of the long groove 31b is shallower than the diameter h2 of the linear sensor 2, a radial part of the linear sensor 2 disposed in the long groove 31b protrudes inward from the long groove 31b. Specifically, the diameter h2 of the linear sensor 2 in this embodiment is 0.3 to 1.8 mm, which is larger than that shown in FIG. 1(a), and various diameters such as 0.4 mm, 0.53 mm, 0.85 mm, and 1.5 mm are used depending on the sensor application. For example, for a linear sensor 2 with a diameter of 0.53 mm, the depth h1 of the long groove is 0.2 mm to 0.45 mm, more specifically, the groove depth is 55% to 75% of the sensor diameter (approximately 0.3 mm to 0.4 mm). In dimensional tolerance notation, this is 0.35 ± 0.05 mm. If the groove is shallower than 50% (0.26 mm), it will be shallower than the radius of the linear sensor 2, making it difficult to fix the linear sensor 2. Conversely, if it is deeper than 75%, the area where the linear sensor 2 is pressed against the object to be detected 9 (see Figure 4) will decrease (the stress cross section will decrease), causing the disadvantage of lowering the sensitivity to detect vibration and weakening the output signal.

[0085] When the sensor unit 1 is brought into contact with the object to be detected 9 and pressed against the object to be detected 9 by a fixing tool, the linear sensor 2 is sandwiched between the support 3 and the object to be detected 9 and compressed in the radial direction. As a result, vibration waves and the like generated in the object to be detected 9 are easily transmitted to the linear sensor 2, and the linear sensor 2 is easily deformed by the vibration waves and the like, so that the vibration waves and the like can be detected with high sensitivity. The elastic body 32 is made of an adhesive having elasticity. However, as the elastic body 32, an elastic double-sided tape may be used, or an elastic resin or an adhesive resin (bond) may be used. By forming the bottom surface of the long groove 31b with the elastic body 32, it is possible to suppress the load for fixing the sensor unit 1 to the object to be detected 9 from being applied to the linear sensor 2 more than necessary. In addition, even if the sensor unit 1 is pressed strongly, it is possible to prevent the sensor from being strongly sandwiched between the rigid member 31 and the object to be measured and from breaking down. The elastic body 32 may be a simple foam of rubber or resin with no adhesiveness. However, by providing the elastic body 32 with adhesiveness, it is possible to easily dispose the linear sensor 2 in the long groove 31b.

[0086] In addition to the effects of the second embodiment, the third embodiment has an effect that the linear sensor 2 of a constant length can be attached to a predetermined position where the long groove 31b of the support 3 is formed. The length of the linear sensor 2 arranged on the inner surface of the support 3 is constant by arranging the linear sensor 2 in the long groove 31b. If the length of the linear sensor 2 arranged on the inner surface of the support 3 varies, the sensor sensitivity is likely to vary for each sensor unit 1, but in the sensor unit 1 of the third embodiment, the length of the linear sensor is constant, so the variation in sensor sensitivity can be suppressed. In addition, since the amplifier 274 is provided, the effect of noise on the output signal of the linear sensor 2 can be relatively reduced. That is, the signal-to-noise ratio in the sensor unit 1 can be increased. As a result, a signal stronger against noise such as external electromagnetic noise can be sent to an external measuring instrument, etc., so that a clear output signal can be obtained in the measuring instrument, etc. In addition, since the output signal is amplified by the amplifier 274 and the transmission power is also increased at the same time, the output signal can be delivered to a measuring instrument, etc. located at a greater distance. In vibration measurement of infrastructure equipment and large-scale factory equipment, it may be necessary to send an output signal over a long distance of several tens to several hundreds of meters, and in such a case, a great advantage is obtained. Similarly, if the output signal obtained from the linear sensor 2 is digitized by an electronic circuit mounted on the terminal member 27, it becomes more resistant to noise and enables long-distance communication, and thus a great advantage is obtained. In addition, unlike an analog signal, a clock signal line for transmitting a clock frequency is required when transmitting a digitized output signal, but this can be omitted if a PWM modulation signal or the like is used. In addition, when transmitting a digitized output signal, a shielded cable using a multi-core twisted wire, which is different from a cable for transmitting an analog signal, is used as the signal cable 28.

[0087] Next, a sensor unit 1 according to a fourth embodiment will be described. In the description of the fourth embodiment, differences from the sensor unit 1 according to the third embodiment will be mainly described.

[0088] Fig. 9(a) is a plan view of a sensor unit according to a fourth embodiment, and Fig. 9(b) is a front view of the sensor unit shown in Fig. 9(a). Fig. 10 is an exploded perspective view of the sensor unit shown in Fig. 9. Note that in Fig. 9(b), the thickness of the protective member 4 is exaggerated relative to the thickness of the rigid member 31.

[0089] The sensor unit 1 of the fourth embodiment differs from the sensor unit 1 of the third embodiment shown in Figs. 6 to 8 in the shape of the terminal groove 31a formed on the outer surface of the rigid member 31, in that the sensor unit 1 includes a magnet 6, and in that the sensor unit 1 includes a cap 7 instead of the conductive shield member 5. The protective member 4 of the fourth embodiment is made of a stainless steel film having a thickness of 0.1 mm. However, the protective member 4 may be made of a metal other than stainless steel, or may be made of a resin film having high oil resistance and weather resistance. Furthermore, the thickness of the protective member 4 is preferably thin so as not to interfere with the magnetic force of the magnet 6, but may be any thickness.

[0090] As shown in FIG. 9(a), five projections 31d are formed on the cable guide portion 31c of the terminal groove 31a, which are alternately protruding toward the center in the groove width direction. The signal cable 28 is pinched by these projections 31d and bent slightly multiple times, thereby preventing the signal cable 28 from moving in the longitudinal direction and preventing it from coming out of the cable guide portion 31c. Note that a protective tube such as a shrink tube may be placed over the signal cable 28 from the portion gripped by the projections 31d to the outside of the outer circumferential surface of the cap 7 to prevent the signal cable 28 from being damaged or broken. The terminal groove 31a of the fourth embodiment is formed over a longer range in the circumferential direction of the rigid member 31 than the terminal member 27. This is to change the fitting position of the terminal member 27 according to the variation in the length of the linear sensor 2 drawn out from the inside to the outside of the rigid member 31 through the drawing hole 3b. When the length of the pulled-out linear sensor 2 is long, the terminal member 27 is arranged on the cable guide portion 31c side, and when the length is short, the terminal member 27 is arranged on the pull-out hole 3b side, so that the pulled-out linear sensor 2 can be stored in the terminal groove 31a.

[0091] As shown in FIG. 9(a) and FIG. 9(b), the magnet 6 is disposed in the support through hole 3a. This magnet 6 is a neodymium magnet. The magnet 6 may be a magnet made of a hard magnetic material other than a neodymium magnet, for example, a samarium-cobalt magnet. A magnet with a strong magnetic force is preferable because it can attach the sensor surface to the detection target 9 more strongly even if it has a smaller shape, thereby improving the sensor sensitivity. The magnet 6 is cylindrical with an outer diameter almost the same as the inner diameter of the support through hole 3a. The thickness of the magnet 6 will be described later.

[0092] The cap 7 covers the entire rigid member 31 except for the inner surface where the linear sensor 2 is arranged. As shown in FIG. 10, the cap 7 has a bottomed, low, hollow cylindrical shape in which a disk-shaped cap bottom surface 71 and a cap outer peripheral wall 72 rising from the outer peripheral edge portion of the cap bottom surface 71 are integrally formed. A peripheral wall notch 72a through which the signal cable 28 passes is formed in the cap outer peripheral wall 72 at a position corresponding to the cable guide portion 31c of the rigid member 31. The cap 7 is made of a steel material. The cap 7 is preferably made of a magnetic material, and more preferably made of a soft magnetic material. Furthermore, the cap 7 may be made of a magnet made of a hard magnetic material, in which case the magnet 6 may be omitted. The rigid member 31 and the magnet 6 are each bonded to the cap 7 by an adhesive. Alternatively, the rigid member 31 and the cap 7 may be bonded together with an adhesive, the magnet 6 may be fitted into the support through hole 3a of the rigid member 31, and the adhesive may be poured into the gap between the rigid member 31 and the magnet 6 to bond the rigid member 31 and the magnet 6. If the thickness of the terminal member 27 is greater than the depth of the terminal groove 31a (see FIG. 9(a)), a spacer may be inserted between the cap 7 and the rigid member 31 at a position that avoids the terminal member 27. In this case, the outer surface of the spacer may be bonded to the cap 7, and the inner surface of the spacer may be bonded to the rigid member 31 and the magnet 6.

[0093] FIG. 11(a) is a bottom view showing the sensor unit shown in FIG. 9 with a protective member removed, and FIG. 11(b) is a cross-sectional view taken along line BB of FIG. 11(a).

[0094] As shown in Fig. 11(a), a long groove 31b is formed on the inner surface of the rigid member 31. This long groove 31b is formed in a spiral shape with approximately 1.9 revolutions. The linear sensor 2 is disposed in the long groove 31b. An intermediate portion 2a of the linear sensor 2 is folded back by going around the side of a small pillar 311 formed at the end of the long groove 31b. The linear sensor 2 is covered by a tube 29 except for the intermediate portion 2a and portions 2b near both ends.

[0095] As shown in FIG. 11(b), a radial part of the linear sensor 2 arranged in the long groove 31b protrudes inward from the long groove 31b. The magnet 6 has the same thickness as the rigid member 31. The thickness of the magnet 6 also coincides with the height of the cap outer peripheral wall 72. Therefore, the inner surface of the magnet 6 coincides with the inner surface of the rigid member 31 and the protruding surface of the cap outer peripheral wall 72. When the surface of the object to be detected 9 (see FIG. 4) is made of a magnetic material, the sensor unit 1 can be attached to the object to be detected 9 by magnetic force by contacting the inner surface with the surface of the object to be detected 9. The cap 7 is entirely made of a soft magnetic material, so it is magnetized by the magnetic force of the magnet 6. The magnetic flux generated by the magnet 6 flows back through the magnet 6, the cap 7, and the surface of the object to be detected 9, so that the sensor unit 1 can be firmly fixed to the object to be detected 9. That is, the cap bottom surface 71 covers the outer side surface of the magnet 6, and the cap outer peripheral wall 72 protrudes toward the detectable object 9 side and covers the side surface of the magnet 6 via the rigid member 31, so that a closed magnetic circuit is formed by the magnet 6, the cap 7, and the surface of the detectable object 9. As a result, the sensor unit 1 is strongly attracted to the detectable object 9, and the linear sensor 2 is sandwiched between the rigid member 31 and the detectable object 9 and compressed in the radial direction. As a result, vibration waves and the like generated in the detectable object 9 are easily transmitted to the linear sensor 2, and the linear sensor 2 is easily deformed by the vibration waves and the like, so that the vibration waves and the like can be detected with high sensitivity.

[0096] In addition to the effects of the third embodiment, the fourth embodiment has an effect that the sensor unit 1 can be easily attached to the detection object 9.

[0097] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the claims. For example, in this embodiment, the support 3 is formed by attaching the elastic body 32 to the surface of the rigid member 31, but the elastic body 32 may be omitted. If the elastic body 32 is omitted, the protection function of the linear sensor 2 and the load uniformization function are reduced, but the pressing force of the linear sensor 2 by the support 3 is increased, so that the detection sensitivity can be further improved. In addition, the manufacturing cost can be reduced because the number of parts, namely the elastic body 32, can be reduced. Also, although the example of using a linear sensor assembly consisting of the linear sensor 2, the terminal member 27, and the signal cable 28 has been described, both or one of the terminal member 27 and the signal cable 28 may be omitted. Furthermore, although the example of arranging the linear sensor 2 around one surface of the support 3 has been used, the linear sensor 2 may be arranged in a linear manner. However, when the linear sensor is arranged in a linear manner, the sensor sensitivity becomes directional. Therefore, if the directivity is not desired, it is preferable to arrange the linear sensor 2 around the support 3. Furthermore, in this embodiment, the support through hole 3a is formed at the center of gravity 3c of the support 3, so that the pressing force for pressing the linear sensor 2 against the object to be detected 9 is made more uniform over the entire length of the linear sensor 2, but the support through hole 3a does not necessarily have to be located at the center of gravity 3c. Also, the support through hole 3a may be omitted, and the support 3 may be pressed and fixed against the object to be detected 9 with a clip or the like. Also, when there is little risk of wear, the protective member 4 may be omitted. By omitting it, the linear sensor 2 comes into direct contact with the object to be detected 9, so that more sensitive detection is possible. In addition, the support 3 and the protective member 4 do not have to be disk-shaped, and may be, for example, polygonal plate-shaped or block-shaped. Also, the linear sensor 2 using the piezoelectric body 22 has been described, but the linear sensor 2 may be changed to one using a resistance wire such as conductive rubber or a capacitor wire. In addition, although an example has been shown in which the linear sensor 2 is arranged in an approximately spiral shape on one surface of the support 3, the linear sensor 2 may also be arranged in a wave-like or zigzag shape on one surface of the support 3, or may be arranged in a star-like or gear-tooth shape by winding around the support 3 while bending multiple times toward the inner and outer periphery.In addition, the terminal member 27 shown in FIG. 1(b) may be a flexible substrate having an electronic circuit equipped with an amplifier 274, similar to the third embodiment shown in FIG. 6(a).

[0098] In addition, even if a constituent element is included only in the description of each of the embodiments and modified examples described above, that constituent element may be applied to other embodiments or other modified examples. [Explanation of symbols]

[0099] 1 Sensor unit 2 Linear Sensor 3 Support 4 Protective materials 31 Rigid members 32 Elastic Body

Claims

1. A linear sensor; A support having a rigid member having a rigidity higher than that of the linear sensor; a terminal member to which an end of the linear sensor is connected, the linear sensor is attached to the support; A sensor unit characterized in that the terminal member is disposed on the surface of the support opposite to the surface on which the linear sensor is attached, between the support and a conductive shielding member.

2. A linear sensor; A support having a rigid member having a rigidity higher than that of the linear sensor; a terminal member to which an end of the linear sensor is connected, the linear sensor is attached to the support; The support has a conductor, A sensor unit characterized in that the terminal member is arranged on the surface of the support opposite to the surface on which the linear sensor is attached, between the conductor and a conductive shielding member.

Images