Sensor, sensor unit, sensor-equipped tube, sensor unit-equipped tube, and sensor mounting method

Abstract

This sensor is provided with: a film which has flexibility and of which the electrical characteristics change when being deformed; and an adhesive member that fixes the film to a tube such that the film is disposed along the lateral surface of the tube. The film, in a state of being fixed to the tube, is stretched and becomes narrow at the middle as compared to when in a state of not being fixed to the tube.

Description

Sensor, sensor unit, pipe with sensor, pipe with sensor unit, and sensor installation method

[0001] The present invention relates to a sensor, a sensor unit, a pipe with a sensor, a pipe with a sensor unit, and a sensor installation method.

[0002] One of the functions required of a sensor is to continuously and stably measure the state of an object to be measured that is placed in an environment that is not visible on a daily basis. Examples of such objects to be measured include a fluid flowing in a pipeline and a battery in an electronic device. A mass flow meter described in Patent Document 1 is known as a conventional invention related to a sensor that measures the state of a fluid flowing in a pipeline. Furthermore, an electronic device described in Patent Document 2 is known as a conventional invention related to a sensor that measures the state of a battery in the housing of an electronic device.

[0003] The mass flow meter described in Patent Document 1 includes a driving means and a vibration detecting means. The driving means generates vibrations in a pipe through which a fluid flows. This generates a Coriolis force in the fluid flowing through the pipe. The Coriolis force generates a torsional torque in the pipe, and the vibration detecting means detects the torsional vibration of the pipe due to the torsional torque. In this way, the mass flow meter described in Patent Document 1 detects the mass flow rate of the fluid flowing through the pipe.

[0004] The electronic device described in Patent Document 2 includes a secondary battery, a temperature measurement unit, a charging rate acquisition unit, a connection detection unit, and a power control unit. The power control unit discharges the secondary battery when the temperature of the secondary battery is equal to or higher than a predetermined threshold, the charging rate of the secondary battery is equal to or higher than a predetermined threshold, and an external power source that supplies power to the secondary battery has been connected to the secondary battery for a predetermined period of time. This contributes to reducing the risk of secondary battery expansion.

[0005] JP 58-206926 A JP 2023-43467 A

[0006] The mass flow meter described in Patent Document 1 is placed in an environment where the fluid flowing through the pipe cannot be visually observed on a daily basis. Because the vibration detection means is attached to an extremely small portion of the pipe, there is a risk that the detection sensitivity of the mass flow meter will decrease, for example, when the amount of fluid flowing through the pipe is very small.

[0007] In the electronic device described in Patent Document 2, the secondary battery is placed in an environment that cannot be visually observed on a daily basis, such as inside the housing of the electronic device. In order to reduce the risk of secondary battery expansion, there is a demand for directly detecting expansion of the secondary battery.

[0008] Therefore, an object of the present invention is to provide a sensor, a sensor unit, a pipe with a sensor, a pipe with a sensor unit, and a sensor installation method that can continue to perform stable measurements on objects that are not visible on a daily basis.

[0009] A sensor according to one embodiment of the present invention comprises: a flexible film whose electrical properties change when deformed; and an adhesive member that fixes the film to the tube so that the film conforms to the side of the tube; wherein the film is stretched and constricted when fixed to the tube compared to when not fixed to the tube.

[0010] According to the present invention, it is possible to continue stable measurement of an object to be measured that is not visible on a daily basis.

[0011] FIG. 1 is a perspective view of sensor 1 in a natural length state. FIG. 2 is an exploded perspective view of sensor 1 in a natural length state. FIG. 3 is a plan view showing an example of extension and contraction of sensor 1. FIG. 4 is a diagram showing a method of attaching sensor 1 to pipe 100 according to the first embodiment. FIG. 5 is a perspective view of sensor unit 10. FIG. 6 is an exploded perspective view of sensor 1a in a natural length state. FIG. 7 is a diagram showing a method of attaching sensor unit 10 to pipe 100. FIG. 8 is a perspective view of sensor unit 10a. FIG. 9 is a diagram showing a method of attaching sensor unit 10a to pipe 100. FIG. 10 is a diagram showing a method of attaching sensor 1b to pipe 100 according to a second modified example. FIG. 11 is a diagram showing a method of attaching sensor 1 to pipe 100 according to a third modified example. FIG. 12 is a diagram showing an example of a case where pipe 100 is bent and deformed. FIG. 13 is a diagram showing a method of attaching sensor 1 to pipe 100 according to a fourth modified example. FIG. 14 is an example of the voltage signal Vs when the fluid 101 is not flowing in the first experiment. FIG. 15 is an example of the voltage signal Vs when the fluid 101 is flowing in the first experiment. FIG. 16 is a perspective view of sensor 1c. FIG. 17 is an exploded perspective view of sensor 1c in its natural length state. FIG. 18 is a diagram showing a method of attaching sensor 1c to pipe 100. FIG. 19 is a perspective view of electronic device 20. FIG. 20 is a perspective view of sensor 1d in its natural length state. FIG. 21 is a plan view of sensor 1d in its natural length state. FIG. 22 is a diagram showing an example of a method of attaching sensor 1d to battery 23. FIG. 23 is a diagram showing an example of a method of attaching sensor 1d to battery 23.

[0012] [First embodiment] (Configuration of sensor 1) A sensor 1 according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view of the sensor 1 in its natural length state. Fig. 2 is an exploded perspective view of the sensor 1 in its natural length state. Fig. 3 is a plan view showing an example of expansion and contraction of the sensor 1.

[0013] In the sensor 1, directions are defined as follows, for example. As shown in FIG. 2 , when the sensor 1 is at its natural length, the direction in which the long side LS4 of the first main surface S1 extends is defined as the left-right direction. When the sensor 1 is at its natural length, the direction in which the short side SS4 of the first main surface S1 extends is defined as the front-rear direction. When the sensor 1 is at its natural length, the direction in which the first main surface S1 and the second main surface S2 are aligned is defined as the up-down direction. The left-right direction, front-rear direction, and up-down direction are perpendicular to each other. Viewing the sensor 1 from above or below corresponds to a "planar view" according to the present invention. However, the left-right direction, front-rear direction, and up-down direction in this specification are defined for the convenience of explanation and may not coincide with the left-right direction, front-rear direction, and up-down direction when the sensor 1 is in use. Furthermore, in each drawing, the left and right directions may be interchanged, the front and rear directions may be interchanged, and the up and down directions may be interchanged.

[0014] As an example, the sensor 1 is attached to a pipe through which a fluid flows and detects the condition of the pipe. As shown in FIG. 1 , the sensor 1 includes an FPC 2, a first electrode 3, a film 4, a second electrode 5, and a first adhesive member 6. The FPC 2, the first electrode 3, the film 4, the second electrode 5, and the first adhesive member 6 are stacked vertically. In this embodiment, the second electrode 5, the film 4, the first electrode 3, the FPC 2, and the first adhesive member 6 are stacked downward in this order. Note that the pipe according to the present invention is not limited to being hollow, and may be solid. The film 4 corresponds to the film according to the present invention. The FPC 2 corresponds to the insulating substrate according to the present invention. The first adhesive member 6 corresponds to the adhesive member according to the present invention.

[0015] In this embodiment, the sensor 1 is in the form of a film. When the sensor 1 is in its natural length state, it has a front long side and a rear long side extending in the left-right direction, and a left short side and a right short side extending in the front-rear direction. However, the sensor 1 does not have to be in the form of a film.

[0016] The FPC 2 is a flexible insulating substrate. Examples of materials for the FPC 2 include polyimide, PET (Poly Ethylene Terephthalate), and liquid crystal polymer. As shown in FIG. 2 , the FPC 2 is in the form of a film. The FPC 2 has an upper main surface and a lower main surface that are arranged in this order along a downward direction. When in their natural lengths, the upper and lower main surfaces of the FPC 2 each have a rectangular shape with two long sides extending in the left-right direction and two short sides extending in the front-to-back direction. The shape and arrangement of the FPC 2 are not limited to those shown in this embodiment. Furthermore, the FPC 2 is not an essential component of the present invention.

[0017] The first electrode 3 is flexible and conductive. The material of the first electrode 3 is, for example, copper. The first electrode 3 is in the form of a film. The first electrode 3 has an upper main surface and a lower main surface aligned in this order along a downward direction. The upper and lower main surfaces of the first electrode 3 each have a rectangular shape with two long sides extending in the left-right direction and two short sides extending in the front-back direction when in their natural lengths. The first electrode 3 is formed on the upper main surface of the FPC 2. In this embodiment, the first electrode 3 covers the upper main surface of the FPC 2. The first electrode 3 functions as a signal electrode for outputting the potential difference generated by the film 4 as an electric charge. The shape and arrangement of the first electrode 3 are not limited to those shown in this embodiment. Furthermore, the first electrode 3 is not an essential component of the present invention.

[0018] The film 4 is flexible. The film 4 is film-like. When the film 4 is at its natural length, it has a rectangular shape with long sides LS4 and short sides SS4 when viewed in the vertical direction. More specifically, the film 4 has a first main surface S1 and a second main surface S2 arranged in this order along the downward direction. Furthermore, when at their natural lengths, the first main surface S1 and the second main surface S2 each have a rectangular shape with two long sides LS4 extending in the left-right direction and two short sides SS4 extending in the front-to-back direction. The film 4 is provided on the upper main surface of the first electrode 3. In this embodiment, the film 4 covers the upper main surface of the first electrode 3. Note that the shape and arrangement of the film according to the present invention are not limited to the shape and arrangement of the film 4.

[0019] In this embodiment, the film 4 is a piezoelectric film. The film 4 is polarized by deformation, generating a potential difference between the first main surface S1 and the second main surface S2. The potential difference generated between the first main surface S1 and the second main surface S2 depends on the amount of deformation of the film 4.

[0020] The film 4 is, for example, a film formed from a chiral polymer. The chiral polymer is, for example, polylactic acid (PLA) such as poly-L-lactic acid (PLLA) and poly-D-lactic acid (PDLA). The main chain of PLA has a helical structure. PLA has piezoelectricity in which the molecules are oriented in the orientation direction OD when uniaxially stretched. The film 4 has a piezoelectric constant of d14. The film 4 may also be a film formed from PVDF, for example.

[0021] The PLA is stretched in an orientation direction OD. When the film 4 is unfolded on a plane, the orientation direction OD of the PLA forms a 45-degree angle with respect to each of the left-right direction and the front-back direction. Note that the 45-degree angle may be within a range of approximately 45 degrees ±10 degrees. When the film 4 is stretched or compressed in the left-right direction, a potential difference is generated between the first main surface S1 and the second main surface S2. Similarly, when the film 4 is stretched or compressed along the front-back direction, a potential difference is generated between the first main surface S1 and the second main surface S2. In this embodiment, the magnitude of the potential difference generated between the first main surface S1 and the second main surface S2 is proportional to the time differential of the deformation of the film 4. Note that the magnitude of the potential difference generated between the first main surface S1 and the second main surface S2 does not have to be proportional to the time differential of the deformation of the film 4.

[0022] The second electrode 5 is flexible and conductive. The material of the second electrode 5 is, for example, copper. The second electrode 5 is in the form of a film. The second electrode 5 has an upper main surface and a lower main surface arranged in this order along a downward direction. The upper and lower main surfaces of the second electrode 5 each have a rectangular shape with two long sides extending in the left-right direction and two short sides extending in the front-back direction when in their natural lengths. The second electrode 5 is provided on the first main surface S1. In this embodiment, the second electrode 5 covers the first main surface S1. The second electrode 5 is connected to a ground potential and functions as a reference electrode and a shield conductor. The shape and arrangement of the second electrode 5 are not limited to those shown in this embodiment. Furthermore, the second electrode 5 is not an essential component of the present invention.

[0023] The first adhesive member 6 is flexible. The first adhesive member 6 is in the form of a film. The first adhesive member 6 has an upper main surface and a lower main surface that are arranged in this order along a downward direction. When in a natural length state, the upper main surface and the lower main surface of the first adhesive member 6 each have a rectangular shape with two long sides extending in the left-right direction and two short sides extending in the front-rear direction. The first adhesive member 6 is provided on the lower main surface of the FPC 2. In this embodiment, the first adhesive member 6 covers the lower main surface of the FPC 2.

[0024] In this embodiment, the first adhesive member 6 is a double-sided tape. That is, the upper main surface and the lower main surface of the first adhesive member 6 each have adhesiveness. When using the sensor 1, the sensor 1 is attached to the side surface of the pipe by bringing the lower main surface of the first adhesive member 6 into close contact with the pipe. This fixes the film 4 to the pipe so that the FPC 2 and the film 4 are aligned with the side surface of the pipe. In this embodiment, when the film 4 is fixed to the pipe, the second main surface S2 of the film 4 is aligned with the side surface of the pipe. Note that the shape and arrangement of the adhesive member according to the present invention are not limited to the shape and arrangement of the first adhesive member 6 shown in this embodiment.

[0025] The sensor 1 is flexible and can flexibly deform. This allows the sensor 1 to be attached to a pipe even if the pipe has irregularities. Furthermore, as shown in FIG. 3 , the sensor 1 and the film 4 can stretch and contract in the left-right direction. When the sensor 1 and the film 4 are at their natural lengths, no tension is generated in the sensor 1 and the film 4. By pulling the left short side of the sensor 1 to the left and the right short side to the right, the sensor 1 stretches in the left-right direction from its natural length. At this time, the film 4 also stretches in the left-right direction from its natural length. Furthermore, by bending the front long side of the sensor 1 so as to protrude rearward and the rear long side so as to protrude forward, the sensor 1 is constricted. At this time, the film 4 is constricted. As the film 4 stretches and constricts in the left-right direction from its natural length, tension is generated in the left portion of the film 4, causing it to contract rightward, and tension is generated in the right portion of the film 4, causing it to contract leftward. The sensor 1 and the film 4 can also stretch and contract in directions other than the left-right direction.

[0026] (Method of attaching sensor 1 to pipe 100) A method of attaching sensor 1 to pipe 100 according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 4 is a diagram showing a method of attaching sensor 1 to pipe 100 according to the first embodiment. Note that in Fig. 4, reference symbols are assigned only to representative long sides LS4 and short sides SS4 of the first main surface S1 of film 4.

[0027] In the pipe 100, directions are defined as follows, for example. As shown in FIG. 4 , one of the axial directions in which the central axis CA100 of the pipe 100 extends is defined as a first axial direction DIRA1. One of the circumferential directions centered on the central axis CA100 of the pipe 100 is defined as a first circumferential direction DIRC1. However, the first axial direction DIRA1 and the first circumferential direction DIRC1 in this specification are defined for the convenience of explanation and are not limited to the example shown in FIG. 4. For example, the first axial direction DIRA1 may be the opposite direction to the first axial direction DIRA1 shown in FIG. 4, and the first circumferential direction DIRC1 may be the opposite direction to the first circumferential direction DIRC1 shown in FIG. 4.

[0028] As shown in FIG. 4 , the pipe 100 is, for example, cylindrical. The central axis CA100 of the pipe 100 extends along the first axial direction DIRA1. The pipe 100 is not limited to a cylindrical shape, and may be any cylindrical shape. The pipe 100 has an inner surface IS100 and an outer surface OS100. This allows a fluid 101 to flow inside the pipe 100. In this embodiment, the fluid 101 is water. The fluid 101 is not limited to water, and may be any liquid or gas.

[0029] In this embodiment, the pipe 100 has elasticity. The elastic pipe 100 is, for example, a vinyl hose.

[0030] The sensor 1 is attached to the side of the pipe 100. More specifically, the sensor 1 is attached to the outer surface OS100 of the pipe 100. This prevents the sensor 1 from coming into contact with the fluid 101. The film 4 is fixed along the outer surface OS100 of the pipe 100. The sensor 1 may also be attached to the inner surface IS100 of the pipe 100.

[0031] The sensor 1 is attached to the outer surface OS100 of the tube 100 in a state in which the film 4 is stretched from its natural length in the direction in which the long side LS4 of the first main surface S1 extends, and the film 4 is constricted. Therefore, when the film 4 is fixed to the outer surface OS100 of the tube 100, it is stretched from its natural length and constricted. In this embodiment, when the film 4 is fixed to the outer surface OS100 of the tube 100, it is stretched in the direction in which the long side LS4 of the first main surface S1 extends and constricted. Therefore, at this time, tension is generated in the left portion of the film 4, causing it to shrink to the right, and tension is generated in the right portion, causing it to shrink to the left. Note that when the film 4 is fixed to the outer surface OS100 of the tube 100, it may be stretched from its natural length in a direction other than the direction in which the long side LS4 of the first main surface S1 extends and constricted.

[0032] In this embodiment, the sensor 1 is attached to the outer surface OS100 of the tube 100 so that the direction in which the long side LS4 of the first main surface S1 extends coincides with the first circumferential direction DIRC1 when the film 4 is fixed to the outer surface OS100 of the tube 100. Note that when the film 4 is fixed to the outer surface OS100 of the tube 100, the direction in which the long side LS4 of the first main surface S1 extends does not have to completely coincide with the first circumferential direction DIRC1. When the film 4 is fixed to the outer surface OS100 of the tube 100, the direction in which the long side LS4 of the first main surface S1 extends may be inclined within a range of approximately ±5 degrees with respect to the first circumferential direction DIRC1.

[0033] In this embodiment, the film 4 is provided on the outer surface OS100 of the tube 100 over half the circumference of the tube 100 centered on the central axis CA100 of the tube 100 when the film 4 is fixed to the outer surface OS100 of the tube 100. Note that the film 4 may also be provided on the outer surface OS100 of the tube 100 over less than half the circumference of the tube 100 centered on the central axis CA100 of the tube 100 when the film 4 is fixed to the outer surface OS100 of the tube 100.

[0034] The sensor 1 can continue to stably measure an object to be measured that is not visible on a daily basis. The sensor 1 has excellent sensitivity for detecting the state of the tube 100. More specifically, the film 4 is polarized by deformation, generating a potential difference between the first main surface S1 and the second main surface S2. The potential difference generated between the first main surface S1 and the second main surface S2 corresponds to the amount of deformation of the film 4. In particular, in this embodiment, the magnitude of the potential difference generated between the first main surface S1 and the second main surface S2 is proportional to the time derivative of the amount of deformation of the film 4. The film 4 is fixed to the tube 100.

[0035] When the fluid 101 is not flowing inside the tube 100, the film 4 does not deform, and the magnitude of the potential difference generated between the first main surface S1 and the second main surface S2 is approximately zero.

[0036] When the fluid 101 starts to flow inside the tube 100, the tube 100 expands in the radial direction around the central axis CA100 of the tube 100. This causes the film 4 to deform so as to be curved in the radial direction, generating a potential difference between the first main surface S1 and the second main surface S2. The polarity of the potential difference generated at this time is defined as positive.

[0037] As the flow rate of the fluid 101 increases, the radial expansion of the tube 100 further increases, which in turn increases the radial deformation of the film 4, generating a positive potential difference between the first principal surface S1 and the second principal surface S2.

[0038] When the flow rate of the fluid 101 decreases, the radial expansion of the tube 100 decreases. As a result, the radial deformation of the film 4 also decreases, and a negative potential difference occurs between the first main surface S1 and the second main surface S2.

[0039] When the fluid 101 flowing inside the tube 100 begins to stop, the amount of radial expansion of the tube 100 becomes approximately zero. As a result, the amount of radial deformation of the film 4 also decreases, and a negative potential difference is generated between the first main surface S1 and the second main surface S2.

[0040] After the fluid 101 flowing inside the tube 100 stops, the time differential value of the radial expansion of the tube 100 becomes approximately zero. As a result, the time differential value of the radial deformation of the film 4 also becomes approximately zero, and the magnitude of the potential difference generated between the first principal surface S1 and the second principal surface S2 becomes approximately zero.

[0041] Therefore, the film 4 can detect an increase or decrease in the flow rate of the fluid 101. Furthermore, when the fluid 101 flows inside the tube 100, the tube 100 vibrates. This deforms the film 4, and an AC potential difference is generated between the first main surface S1 and the second main surface S2. On the other hand, when the fluid 101 that was flowing inside the tube 100 stops, the vibration of the tube 100 stops. This stops the deformation of the film 4, and the AC potential difference that was generated between the first main surface S1 and the second main surface S2 becomes approximately zero. Therefore, the film 4 can detect whether the fluid 101 is flowing inside the tube 100.

[0042] Furthermore, even if a blockage occurs in the pipe 100, the amount of radial expansion of the pipe 100 increases, and therefore the film 4 can detect a blockage in the pipe 100 regardless of whether the flow rate of the fluid 101 increases or decreases. As a result, the film 4 can predict the rupture of the pipe 100 in advance.

[0043] Incidentally, in order to improve the detection sensitivity of the state of the tube 100, it is necessary to more reliably detect the expansion of the tube 100. Therefore, in the sensor 1, the film 4 is stretched from its natural length and constricted when it is fixed to the tube 100. As a result, when the tube 100 expands, the film 4 deforms more reliably compared to when the film 4 is loosened when fixed to the tube 100. Therefore, the sensor 1 can more reliably detect the expansion of the tube 100. As a result, the sensor 1 has excellent detection sensitivity of the state of the tube 100 and can continue to stably measure the state of the tube 100 even when, for example, a small amount of fluid is flowing through the pipe.

[0044] Furthermore, the sensor 1 can instantly detect the state of the pipe 100. More specifically, the piezoelectric element has excellent responsiveness. Therefore, the film 4 instantly generates a potential difference between the first main surface S1 and the second main surface S2 due to deformation. As a result, the sensor 1 can instantly detect the state of the pipe 100.

[0045] Furthermore, sensor 1 can easily improve the detection sensitivity of the state of tube 100. More specifically, while film 4 is fixed to tube 100, it is stretched and constricted in the direction in which long side LS4 of first main surface S1 extends. This makes it easier to stretch film 4 from its natural length and constrict it, compared to when film 4 is stretched and constricted in the direction in which short side SS4 of first main surface S1 extends. Therefore, sensor 1 can easily improve the detection sensitivity of the state of tube 100.

[0046] Furthermore, sensor 1 can more reliably improve the detection sensitivity of the state of tube 100. More specifically, when film 4 is fixed to tube 100, the direction in which long side LS4 of first main surface S1 extends coincides with first circumferential direction DIRC1. This allows fluid 101 to flow near film 4 even when the flow rate of fluid 101 is small, making it easier for expansion or vibration of tube 100 to be transmitted to film 4 more reliably. Therefore, even when the flow rate of fluid 101 is small, film 4 can more reliably deform. As a result, sensor 1 can more reliably improve the detection sensitivity of the state of tube 100.

[0047] Furthermore, sensor 1 can more reliably improve the detection sensitivity of the state of tube 100. More specifically, in sensor 1, film 4, when fixed to tube 100, is provided on tube 100 over half the circumference of tube 100 centered on central axis CA100 of tube 100. This allows fluid 101 to flow near film 4 even when the diameter of tube 100 is large, making it easier for expansion or vibration of tube 100 to be reliably transmitted to film 4. Therefore, even when the diameter of tube 100 is large, film 4 can more reliably deform. As a result, sensor 1 can more reliably improve the detection sensitivity of the state of tube 100.

[0048] Furthermore, when the fluid 101 is a gas, the amount of expansion or vibration of the tube 100 is likely to be smaller than when the fluid 101 is a liquid. Even in this case, the expansion or vibration of the tube 100 is more reliably transmitted to the film 4, so that the film 4 is more reliably deformed. As a result, the sensor 1 can more reliably improve the detection sensitivity of the state of the tube 100. Note that, when the film 4 is fixed to the tube 100, it may be provided on the tube 100 over more than half the circumference of the tube 100 centered on the central axis CA100 of the tube 100.

[0049] Furthermore, sensor 1 can more reliably improve the detection sensitivity of the state of tube 100. More specifically, when film 4 is unfolded flat, orientation direction OD forms a 45-degree angle with respect to both the left-right direction and the front-back direction. This allows the direction of highest piezoelectricity of film 4 to coincide with the direction in which long side LS4 of first main surface S1 extends. Therefore, when tube 100 expands radially about central axis CA100 of tube 100, the displacement detection direction (bending direction) of film 4 can be matched with the direction in which long side LS4 of first main surface S1, which is most susceptible to deformation, extends. This allows film 4 to have high sensitivity. As a result, sensor 1 can more reliably improve the detection sensitivity of the state of tube 100.

[0050] Second Embodiment (Configuration of Sensor Unit 10) A sensor unit 10 according to a second embodiment of the present invention will be described below with reference to the drawings. Fig. 5 is a perspective view of the sensor unit 10. Note that in Fig. 5, only the representative long side LS4 of the two long sides LS4 of the first main surface S1 of the film 4 is labeled with a reference symbol. Fig. 6 is an exploded perspective view of the sensor 1a in its natural length state.

[0051] In the sensor unit 10, directions are defined as follows, for example. As shown in FIG. 5 , one of the axial directions in which the central axis CA10 of the sensor unit 10 extends is defined as a second axial direction DIRA2. One of the circumferential directions centered on the central axis CA10 of the sensor unit 10 is defined as a second circumferential direction DIRC2. However, the second axial direction DIRA2 and the second circumferential direction DIRC2 in this specification are defined for the convenience of explanation and are not limited to the example shown in FIG. 5 . For example, the second axial direction DIRA2 may be the opposite direction to the second axial direction DIRA2 shown in FIG. 5 , and the second circumferential direction DIRC2 may be the opposite direction to the second circumferential direction DIRC2 shown in FIG. 5 .

[0052] 5, in this embodiment, the sensor 1a and the protective member 11 constitute the sensor unit 10. That is, the sensor unit 10 includes the sensor 1a and the protective member 11. Note that with regard to the sensor 1a, only the differences from the sensor 1 will be described, and the rest will be omitted.

[0053] As shown in FIG. 6, the sensor 1 a differs from the sensor 1 in that it further includes a second adhesive member 7 .

[0054] The second adhesive member 7 is flexible. The second adhesive member 7 is in the form of a film. The second adhesive member 7 has an upper main surface and a lower main surface that are arranged in this order along a downward direction. When in its natural length, each second adhesive member 7 has a rectangular shape with two long sides extending in the left-right direction and two short sides extending in the front-rear direction. The second adhesive member 7 is provided on the upper main surface of the second electrode 5. In this embodiment, the second adhesive member 7 covers the upper main surface of the second electrode 5.

[0055] In this embodiment, the second adhesive member 7 is a double-sided tape. That is, the upper main surface and the lower main surface of the second adhesive member 7 each have adhesiveness. In the sensor unit 10, the upper main surface of the second adhesive member 7 is attached to the protective member 11. Note that the shape and arrangement of the second adhesive member according to the present invention are not limited to the shape and arrangement of the second adhesive member 7. Furthermore, the second adhesive member 7 is not an essential component of the present invention.

[0056] In this embodiment, the second adhesive member 7 has insulating properties. However, the second adhesive member 7 may also have conductive properties.

[0057] 5, the protective member 11 is, for example, a rectangular cylindrical shape. The protective member 11 is not limited to a rectangular cylindrical shape, and may be any cylindrical shape. The protective member 11 has an inner surface IS11 and an outer surface OS11. The inner surface IS11 has a shape that conforms to the outer surface OS100 of the pipe 100.

[0058] In this embodiment, the protective member 11 is flexible. The protective member 11 is harder than the sensor 1a. The protective member 11 is conductive. The protective member 11 does not have to be flexible. The protective member 11 does not have to be harder than the sensor 1a. The protective member 11 may be insulating.

[0059] The sensor 1a is attached to the inner surface IS11 of the protective member 11. More specifically, the upper main surface of the second adhesive member 7 is attached to the inner surface IS11 of the protective member 11. In this way, the protective member 11 covers the first main surface S1 of the film 4.

[0060] The sensor 1a is attached to the inner surface IS11 of the protective member 11 with the film 4 stretched from its natural length in the direction in which the long side LS4 of the first main surface S1 extends, and the film 4 is constricted. Therefore, in the sensor unit 10, tension is generated in the left portion of the sensor 1a, causing it to contract to the right, and tension is generated in the right portion, causing it to contract to the left. Note that, when the film 4 is fixed to the inner surface IS11 of the protective member 11, it may be stretched from its natural length in a direction other than the direction in which the long side LS4 of the first main surface S1 extends, causing it to be constricted.

[0061] However, in this embodiment, the sensor 1a is attached to the inner surface IS11 of the protective member 11 so that the extension direction of the long side LS4 of the first main surface S1 coincides with the second circumferential direction DIRC2. Note that the extension direction of the long side LS4 of the first main surface S1 does not have to coincide completely with the second circumferential direction DIRC2. The extension direction of the long side LS4 of the first main surface S1 may be inclined within a range of approximately ±5 degrees with respect to the second circumferential direction DIRC2.

[0062] (Method of attaching sensor unit 10 to pipe 100) A method of attaching sensor unit 10 to pipe 100 according to a second embodiment of the present invention will be described below with reference to the drawings. Fig. 7 is a diagram showing a method of attaching sensor unit 10 to pipe 100. Note that in Fig. 7, only the representative long side LS4 of the two long sides LS4 of first main surface S1 of film 4 is denoted by a reference symbol.

[0063] As shown in FIG. 7 , the sensor unit 10 is attached to the tube 100 so that the inner surface IS11 of the protective member 11 fits into the outer surface OS100 of the tube 100. This secures the film 4 to the outer surface OS100 of the tube 100. Therefore, when the film 4 is secured to the outer surface OS100 of the tube 100, the inner surface IS11 of the protective member 11 fits into the outer surface OS100 of the tube 100. This ensures that when the film 4 is secured to the outer surface OS100 of the tube 100, the protective member 11 is provided on the outer surface OS100 of the tube 100 around the central axis CA100 of the tube 100, all around the circumference of the tube 100. Note that the protective member 11 does not necessarily have to be provided on the outer surface OS100 of the tube 100 around the central axis CA100 of the tube 100.

[0064] In this embodiment, when the film 4 is fixed to the outer surface OS100 of the tube 100, the second axial direction DIRA2 coincides with the first axial direction DIRA1, and the second circumferential direction DIRC2 coincides with the first axial direction DIRA1. Therefore, when the film 4 is fixed to the outer surface OS100 of the tube 100, the direction in which the long side LS4 of the first main surface S1 extends coincides with the first circumferential direction DIRC. Furthermore, when the film 4 is fixed to the outer surface OS100 of the tube 100, the lower main surface of the first adhesive member 6 is in close contact with the outer surface OS100 of the tube 100. Note that the first adhesive member 6 is not essential in this embodiment.

[0065] The sensor unit 10 also achieves the same effect as the sensor 1. Furthermore, the sensor unit 10 can suppress the effects of pressure and the like from outside the tube 100. More specifically, the protective member 11 covers the first main surface S1 of the film 4. This can suppress deformation of the film 4 due to pressure being applied to the first main surface S1 of the film 4 from outside the tube 100. Therefore, the sensor unit 10 can suppress the effects of pressure and the like from outside the tube 100.

[0066] Since the protective member 11 is harder than the sensor 1a, deformation of the film 4 due to pressure being applied to the first main surface S1 of the film 4 from outside the tube 100 can be more effectively prevented. Furthermore, since the protective member 11 is conductive, it can be more effectively prevented electromagnetic noise from outside the tube 100 from penetrating the film 4 and electromagnetic noise emitted by the film 4 from diffusing outside the tube 100.

[0067] Furthermore, sensor unit 10 can further suppress the effects of pressure and the like from outside tube 100. More specifically, when film 4 is fixed to tube 100, protective member 11 is provided on tube 100 around the entire circumference of tube 100, centered on central axis CA100 of tube 100. This suppresses pressure not only on first main surface S1 of film 4 but also on sensor 1a and the outer surface OS100 of tube 100 near sensor 1a, thereby further suppressing deformation of film 4. Therefore, sensor unit 10 can further suppress the effects of pressure and the like from outside tube 100.

[0068] In the method of attaching sensor unit 10 to pipe 100, sensor 1a and protective member 11 do not necessarily constitute sensor unit 10. That is, after sensor 1 or sensor 1a is attached to the outer surface OS100 of pipe 100, protective member 11 covering film 4 may be attached to outer surface OS100 of pipe 100. In this case, the same effect as in the method of attaching sensor unit 10 to pipe 100 can be achieved.

[0069] [First Modification] (Configuration of Sensor Unit 10a) A sensor unit 10a according to a first modification of the present invention will be described below with reference to the drawings. Fig. 8 is a perspective view of the sensor unit 10a. Note that only the parts of the sensor unit 10a that are different from the sensor unit 10 will be described, and the rest will be omitted.

[0070] As shown in FIG. 8, sensor unit 10a differs from sensor unit 10 in that protective member 11 is divided into first protective member 11a and second protective member 11b.

[0071] In this modification, the first protective member 11 a and the second protective member 11 b have the same shape. The sensor 1 a is attached to the first protective member 11 a. Note that the first protective member 11 a and the second protective member 11 b do not necessarily have to have the same shape.

[0072] (Method of attaching sensor unit 10a to pipe 100) A method of attaching sensor unit 10a to pipe 100 according to a first modified example of the present invention will now be described with reference to the drawings. Fig. 9 is a diagram showing a method of attaching sensor unit 10a to pipe 100.

[0073] 9, the sensor unit 10a is attached to the pipe 100 so that the pipe 100 is sandwiched between the first protective member 11a and the second protective member 11b. Then, the second protective member 11b is fixed to the first protective member 11a.

[0074] The sensor unit 10a also provides the same effects as the sensor unit 10.

[0075] [Second Modification] (Method of Mounting Sensor 1b to Pipe 100) A method of mounting sensor 1b to pipe 100 according to a second modification of the present invention will be described below with reference to the drawings. FIG. 10 is a diagram showing a method of mounting sensor 1b to pipe 100 according to the second modification. Note that in FIG. 10, only the representative long side LS4 of the two long sides LS4 of the first main surface S1 of film 4 is labeled with a reference symbol. Furthermore, with regard to the method of mounting sensor 1b to pipe 100 according to the second modification, only the parts that differ from the method of mounting sensor 1b to pipe 100 according to the first embodiment will be described, and the rest will be omitted.

[0076] 10, sensor 1b differs from sensor 1 in that the length of long side LS4 of first main surface S1 of film 4 is the same as the length of the entire circumference of tube 100 centered on central axis CA100 of tube 100. Note that in this modification, the length of long side LS4 of first main surface S1 of film 4 only needs to be equal to or greater than the length of the entire circumference of tube 100 centered on central axis CA100 of tube 100.

[0077] In addition, this modified example differs from the method of attaching sensor 1 to pipe 100 in the first embodiment in that sensor 1b is attached so that film 4 is provided on the outer surface OS100 of pipe 100 around the entire circumference of pipe 100 centered on the central axis CA100 of pipe 100.

[0078] Sensor 1b also achieves the same effect as sensor 1. Furthermore, sensor 1b can more reliably improve the detection sensitivity of the state of tube 100. More specifically, in sensor 1b, film 4 is provided on tube 100 around the entire circumference of tube 100, centered on central axis CA100 of tube 100, while being fixed to tube 100. This allows fluid 101 to flow near film 4 even when the flow rate of fluid 101 is small, making it easier for expansion or vibration of tube 100 to be reliably transmitted to film 4. Therefore, even when the flow rate of fluid 101 is small, film 4 deforms more reliably. As a result, sensor 1b can more reliably improve the detection sensitivity of the state of tube 100.

[0079] [Third Modification] (Method of Attaching Sensor 1 to Pipe 100) A method of attaching sensor 1 to pipe 100 according to a third modification of the present invention will be described below with reference to the drawings. FIG. 11 is a diagram showing a method of attaching sensor 1 to pipe 100 according to the third modification. Note that in FIG. 11, only the representative long side LS4 of the two long sides LS4 of the first main surface S1 of film 4 is labeled with a reference symbol. FIG. 12 is a diagram showing an example of a case where pipe 100 is bent and deformed. In addition, with regard to the method of attaching sensor 1 to pipe 100 according to the third modification, only the parts that are different from the method of attaching sensor 1 to pipe 100 according to the first embodiment will be described, and the rest will be omitted.

[0080] As shown in Figure 11, this modified example differs from the method of attaching sensor 1 to tube 100 in the first embodiment in that, when film 4 is fixed to the outer surface OS100 of tube 100, sensor 1 is attached to the outer surface OS100 of tube 100 so that the direction in which long side LS4 of first main surface S1 extends coincides with first axial direction DIRA1.

[0081] In addition, when the film 4 is fixed to the outer surface OS100 of the tube 100, the direction in which the long side LS4 of the first main surface S1 extends does not have to completely coincide with the first axial direction DIRA1. When the film 4 is fixed to the outer surface OS100 of the tube 100, the direction in which the long side LS4 of the first main surface S1 extends may be inclined within a range of about ±5 degrees with respect to the first axial direction DIRA1.

[0082] The method of attaching sensor 1 to pipe 100 according to the third modification also achieves the same effects as the method of attaching sensor 1 to pipe 100 according to the first embodiment. Furthermore, according to the method of attaching sensor 1 to pipe 100 according to the third modification, when film 4 is fixed to pipe 100, the direction in which long side LS4 of first main surface S1 extends coincides with first axis direction DIRA1. As a result, even if external pressure is applied to pipe 100 and pipe 100 is bent as shown in FIG. 12 , the film 4 deforms in response to the bending deformation of pipe 100, making it possible to detect the bending deformation of pipe 100. Therefore, according to the method of attaching sensor 1 to pipe 100 according to the third modification, it is possible to predict in advance the destruction of pipe 100.

[0083] [Fourth Modification] (Method of Attaching Sensor 1 to Pipe 100) A method of attaching sensor 1 to pipe 100 according to a fourth modification of the present invention will be described below with reference to the drawings. Fig. 13 is a diagram showing a method of attaching sensor 1 to pipe 100 according to the fourth modification. Note that in Fig. 13, only the representative long side LS4 of the two long sides LS4 of the first main surface S1 of film 4 is denoted by a reference symbol. Furthermore, with regard to the method of attaching sensor 1 to pipe 100 according to the fourth modification, only the parts that differ from the method of attaching sensor 1 to pipe 100 according to the first embodiment will be described, and the rest will be omitted.

[0084] As shown in Figure 13, this modified example differs from the method of attaching sensor 1 to tube 100 in the first embodiment in that, with film 4 fixed to the outer surface OS100 of tube 100, sensor 1 is attached to the outer surface OS100 of tube 100 so that it is spirally wrapped around the outer surface OS100 of tube 100.

[0085] The inventors of the present application conducted an experiment to confirm the sensitivity of sensor 1 to detecting the state of tube 100 when sensor 1 was attached so that film 4 was spirally wrapped around the outer surface OS100 of tube 100. In this experiment, first electrode 3 was connected to a charge amplifier (not shown) and the voltage signal Vs was measured after the charge output by first electrode 3 was converted into the voltage signal Vs.

[0086] In the experiments, a vinyl hose was used as the pipe 100. Water was used as the fluid 101, and experiments were conducted in the following cases: when the hose outer diameter was 4 mm and the hose inner diameter was 2.5 mm (hereinafter referred to as the first experiment); when the hose outer diameter was 6 mm and the hose inner diameter was 4 mm (hereinafter referred to as the second experiment); and when the hose outer diameter was 15 mm and the hose inner diameter was 9 mm (hereinafter referred to as the third experiment).

[0087] Furthermore, an experiment was conducted in which the fluid 101 was air, the outer diameter of the hose was 6 mm, and the inner diameter of the hose was 4 mm (hereinafter referred to as the fourth experiment). In the fourth experiment, the flow rate of the fluid 101 was changed. More specifically, in the fourth experiment, the flow rate of the fluid 101 was changed in three ways: to a level at which dust flies (hereinafter referred to as the small flow rate), to a level at which the pen moves (hereinafter referred to as the medium flow rate), and to a level at which a person's skin is deeply indented (hereinafter referred to as the large flow rate).

[0088] FIG. 14 shows an example of the voltage signal Vs when the fluid 101 is not flowing in the first experiment. FIG. 15 shows an example of the voltage signal Vs when the fluid 101 is flowing in the first experiment. The horizontal axes in FIGS. 14 and 15 represent time. The vertical axes in FIGS. 14 and 15 represent the voltage signal Vs. As shown in FIG. 14 , in the first experiment, the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 is not flowing was 120 mV. As shown in FIG. 15 , in the first experiment, the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 is flowing was 430 mV. It was confirmed in the first experiment that the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 is flowing was greater than the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 is not flowing.

[0089] In the second experiment, the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 was not flowing was 180 mV, and the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 was flowing was 1080 mV.

[0090] In the third experiment, the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 was not flowing was 120 mV, and the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 was flowing was 480 mV.

[0091] The first to third experiments confirmed that, for example, by inputting the voltage signal Vs or the peak-to-peak value Vspp of the voltage signal Vs into a determination circuit (not shown) with a threshold set to 200 mV, the determination circuit can determine that the fluid 101 is not flowing if the peak-to-peak value Vspp of the voltage signal Vs is equal to or less than the threshold, and can determine that the fluid 101 is flowing if the peak-to-peak value Vspp of the voltage signal Vs is greater than the threshold. In other words, the voltage signal Vs can be used to determine whether the fluid 101 is flowing. Furthermore, the sensor 1 can be used to determine whether the fluid 101 is flowing.

[0092] The first to third experiments confirmed that even if the outer and inner diameters of the hose change, the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 is flowing is greater than the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 is not flowing.

[0093] In the fourth experiment, the peak-to-peak value Vspp of the voltage signal Vs when the fluid 101 was not flowing was 160 mV. The peak-to-peak value Vspp of the voltage signal Vs in the case of a small flow rate was 240 mV. The peak-to-peak value Vspp of the voltage signal Vs in the case of a medium flow rate was 410 mV. The peak-to-peak value Vspp of the voltage signal Vs in the case of a large flow rate was 1090 mV.

[0094] The second and fourth experiments confirmed that the fluid 101 is not limited to a liquid, but may be a gas. Furthermore, the fourth experiment confirmed that the greater the flow rate of the fluid 101, the greater the peak-to-peak value Vspp of the voltage signal Vs. Therefore, the sensor 1 can be used to measure the flow rate of the fluid 101.

[0095] The method of attaching the sensor 1 to the pipe 100 according to the fourth modification also achieves the same effects as the method of attaching the sensor 1 to the pipe 100 according to the first embodiment. Furthermore, the method of attaching the sensor 1 to the pipe 100 according to the fourth modification allows the sensor 1 to be attached to a curved portion of the pipe 100. When the pipe 100 has a curved portion, clogging and leakage of the fluid 101 are likely to occur at the curved portion of the pipe 100. Therefore, the method of attaching the sensor 1 to the pipe 100 according to the fourth modification makes it easier to detect clogging and leakage of the fluid 101 when the pipe 100 has a curved portion, and can more reliably improve the sensitivity of detecting the state of the pipe 100.

[0096] [Third embodiment] (Configuration of sensor 1c) A sensor 1c according to a third embodiment of the present invention will be described below with reference to the drawings. Fig. 16 is a perspective view of sensor 1c. Fig. 17 is an exploded perspective view of sensor 1c in its natural length state. Note that with regard to sensor 1c, only the parts that are different from sensor 1 will be described, and the rest will be omitted.

[0097] As shown in FIG. 16, sensor 1c differs from sensor 1 in that a first adhesive member 6, a second electrode 5, a film 4, a first electrode 3, and an FPC 2 are stacked downward in this order.

[0098] In this modified example, the first adhesive member 6 is provided on the upper main surface of the second electrode 5. In this embodiment, the first adhesive member 6 covers the upper main surface of the second electrode 5. In this embodiment, the first adhesive member 6 is a single-sided tape in which only the lower main surface of the first adhesive member 6 is adhesive. In other words, the upper main surface of the first adhesive member 6 does not have adhesiveness.

[0099] 17 , the areas of the upper and lower main surfaces of the first adhesive member 6 are larger than the areas of the upper and lower main surfaces of the FPC 2, the first electrode 3, the film 4, and the second electrode 5. In addition, the first adhesive member 6 has a first region A1 that overlaps with any of the FPC 2, the first electrode 3, the film 4, and the second electrode 5 when viewed in the vertical direction, and a second region A2 that does not overlap with any of the FPC 2, the first electrode 3, the film 4, and the second electrode 5 when viewed in the vertical direction.

[0100] (Method of attaching sensor 1c to pipe 100) A method of attaching sensor 1c to pipe 100 according to a third embodiment of the present invention will be described below with reference to the drawings. Fig. 18 is a diagram showing a method of attaching sensor 1c to pipe 100. Note that with regard to the method of attaching sensor 1c to pipe 100 according to the third embodiment, only the parts that are different from the method of attaching sensor 1c to pipe 100 according to the first embodiment will be described, and the rest will be omitted.

[0101] As shown in Figure 18, this embodiment differs from the method of attaching sensor 1 to pipe 100 in the first embodiment in that sensor 1c is attached to pipe 100 by closely adhering the second area A2 of the lower main surface of first adhesive member 6 and the lower main surface of FPC 2 to pipe 100.

[0102] The sensor 1c also has the same effect as the sensor 1.

[0103] [Fourth embodiment] An electronic device 20 according to a fourth embodiment of the present invention will be described below with reference to the drawings. Fig. 19 is a perspective view of the electronic device 20. Fig. 20 is a perspective view of a sensor 1d in its natural length state. Fig. 21 is an exploded perspective view of the sensor 1d in its natural length state. Note that with regard to sensor 1d, only the parts that differ from sensor 1 will be described, and the rest will be omitted.

[0104] The electronic device 20 is, for example, an active pen. The active pen is used as an input device that allows a user to write directly on the display of a smartphone or tablet computer. As shown in Fig. 19, the electronic device 20 includes a housing 21, a head 22, a battery 23, and a sensor 1d.

[0105] The housing 21 is, for example, cylindrical. The tip of the housing 21 has a tapered shape. That is, the housing 21 becomes thinner toward the tip. The housing 21 is held by a user. The shape of the housing 21 is not limited to a cylindrical shape, and it may also be a rectangular tube shape.

[0106] The head 22 is provided at the tip of the housing 21. The head 22 generates static electricity, which allows the user to use the electronic device 20 to operate a smartphone or a tablet computer.

[0107] The battery 23 is housed in the housing 21. In this embodiment, the battery 23 is cylindrical. The battery 23 has a side surface OS23. The battery 23 supplies power to the head 22. The battery 23 is, for example, a secondary battery such as a lithium ion battery. However, the battery 23 is not limited to a secondary battery such as a lithium ion battery.

[0108] 20 , sensor 1d includes an FPC 2, a film 4, and a first adhesive member 6. The FPC 2, the film 4, and the first adhesive member 6 are stacked in the vertical direction. In this embodiment, the film 4, the FPC 2, and the first adhesive member 6 are stacked downward in this order. Note that the sensor in this embodiment is not limited to sensor 1d, and may be sensors 1, 1b, 1c, etc.

[0109] 21 , in this embodiment, the film 4 includes a strain gauge 4 a whose electrical resistance value changes with deformation. The material of the strain gauge 4 a is, for example, an alloy of copper and nickel. The electrical resistance value of the strain gauge 4 a changes in proportion to the strain. Furthermore, the film according to the present invention may be any film whose electrical properties change with deformation, and may be a piezoelectric film.

[0110] 19 , the sensor 1d is housed in the housing 21. The sensor 1d is attached to the side surface OS23 of the battery 23. More specifically, the sensor 1d is attached to the side surface OS23 of the battery 23 by closely contacting the lower main surface of the first adhesive member 6 with the side surface OS23 of the battery 23. This fixes the film 4 to the battery 23 so that the FPC 2 and the film 4 are aligned along the side surface OS23 of the battery 23.

[0111] In this embodiment, the sensor 1d is attached to the side surface OS23 of the battery 23 in a state in which the film 4 is stretched from its natural length in the direction in which the long side LS4 of the first main surface S1 extends, and the film 4 is constricted. Therefore, when the film 4 is fixed to the side surface OS23 of the battery 23, the film 4 is stretched from its natural length and constricted. Furthermore, when the film 4 is fixed to the side surface OS23 of the battery 23, the film 4 is stretched in the direction in which the long side LS4 of the first main surface S1 extends and constricted. Furthermore, when the film 4 is fixed to the side surface OS23 of the battery 23, the sensor 1d is attached to the side surface OS23 of the battery 23 so as to be spirally wrapped around the side surface OS23 of the battery 23.

[0112] The sensor 1d can also continue to stably measure objects that are not visible on a daily basis. As lithium-ion batteries deteriorate, the electrolyte inside the battery oxidizes, generating gas and causing the battery to expand. This causes the film 4 fixed to the side surface OS23 of the battery 23 to deform, changing the electrical resistance of the strain gauge 4a. By measuring the electrical resistance of the strain gauge 4a, the expansion of the battery 23 can be directly detected.

[0113] Furthermore, in order to more reliably detect the expansion of the battery 23, in the sensor 1d, the film 4 is stretched from its natural length and constricted while it is fixed to the battery 23. This allows the film 4 to deform more reliably when the battery 23 expands, compared to when the film 4 is loose while fixed to the battery 23. Therefore, the sensor 1d can more reliably detect the expansion of the battery 23. As a result, the sensor 1d has excellent sensitivity for detecting the expansion of the battery 23, and can continue to stably measure the state of the battery 23.

[0114] Furthermore, sensor 1d can more reliably detect battery 23 expansion. More specifically, film 4 includes strain gauge 4a, whose electrical resistance changes with deformation. Strain gauges are excellent at detecting static strain. Therefore, even if the deformation of side surface OS23 of battery 23 due to battery 23 expansion is small over time, the strain gauge 4a's electrical resistance changes with deformation. As a result, sensor 1d can more reliably detect battery 23 expansion.

[0115] In addition, when the film 4 is a piezoelectric film, it is excellent at detecting dynamic strain. Therefore, even if the deformation speed of the side surface OS23 of the battery 23 due to the expansion of the battery 23 is fast, the film 4 immediately generates a potential difference between the first main surface S1 and the second main surface S2 due to the deformation. As a result, when the film 4 is a piezoelectric film, the expansion of the battery 23 can be immediately detected.

[0116] Furthermore, sensor 1d can easily improve the sensitivity of detecting the expansion of battery 23. More specifically, when film 4 is fixed to battery 23, it is stretched and constricted in the direction of extension of long side LS4 of first main surface S1. This makes it easier to stretch film 4 from its natural length and constrict it, compared to when film 4 is stretched and constricted in the direction of extension of short side SS4 of first main surface S1. Therefore, sensor 1d can easily improve the sensitivity of detecting the expansion state of battery 23.

[0117] Furthermore, the sensor 1d can more reliably detect the expansion of the battery 23. More specifically, the film 4 is spirally wrapped around the battery 23 while being fixed to the battery 23. This allows the sensor 1d to cover the side surface OS23 of the battery 23 without being biased toward a single portion of the side surface OS23 of the battery 23. Therefore, even if a portion of the battery 23 expands, the sensor 1d can more reliably detect the expansion. Therefore, the sensor 1d can more reliably detect the expansion of the battery 23.

[0118] Furthermore, according to the sensor 1d, when the film 4 is fixed to the battery 23, the FPC 2 is aligned with the side surface OS23 of the battery 23. This makes it easier to connect the FPC 2 to a connecting member such as a connector provided on another circuit board.

[0119] Note that, when the film 4 is fixed to the battery 23, the sensor 1d may be attached to the side surface OS23 of the battery 23 so that the direction in which the long side LS4 of the first main surface S1 extends coincides with the circumferential direction centered on the central axis of the battery 23. Furthermore, when the film 4 is fixed to the battery 23, the sensor 1d may be attached to the side surface OS23 of the battery 23 so that the direction in which the long side LS4 of the first main surface S1 extends coincides with the axial direction in which the central axis of the battery 23 extends.

[0120] [Fifth Modification] (One Example of a Method of Attaching Sensor 1d to Battery 23) Hereinafter, one example of a method of attaching sensor 1d to battery 23 according to a fifth modification of the present invention will be described with reference to the drawings. Fig. 22 is a diagram showing one example of a method of attaching sensor 1d to battery 23. Fig. 23 is a diagram showing one example of a method of attaching sensor 1d to battery 23.

[0121] 22 , in this modification, the battery 23 is rectangular parallelepiped. In this modification as well, the film 4 is fixed to the side surface OS23 of the battery 23, and the sensor 1d is attached to the side surface OS23 of the battery 23 so as to be spirally wrapped around the side surface OS23 of the battery 23. The method of attaching the sensor 1d to the battery 23 according to this modification also achieves the same effects as the method of attaching the sensor 1d to the battery 23 according to the fourth embodiment.

[0122] As shown in FIG. 23, the number of turns spirally wound around the battery 23 may be one.

[0123] Other Embodiments The sensor according to the present invention is not limited to the sensors 1, 1a to 1d, and can be modified within the scope of the gist thereof. In addition, the structures of the sensors 1, 1a to 1d may be combined arbitrarily.

[0124] The sensor unit according to the present invention is not limited to the sensor units 10 and 10a, and can be modified within the scope of the present invention. Furthermore, the structures of the sensor units 10 and 10a may be combined arbitrarily.

[0125] The sensor installation method according to the present invention is not limited to the method of installing sensor 1 to pipe 100 according to the first embodiment, the third modified example, and the fourth modified example, the method of installing sensors 1b and 1c to pipe 100, and the method of installing sensor 1d to battery 23 according to the fourth embodiment and the fifth modified example, but can be modified within the scope of its gist.

[0126] It should be noted that the sensor according to the present invention does not need to be attached to a tube or a battery in a constricted state.

[0127] To prove whether a film is stretched and necked while attached to a tube or battery, simply compare the film while attached to the tube or battery with the film while not attached to the tube or battery. That is, measure the shape and length of the film while attached to the tube or battery, then remove the film from the tube or battery and measure the shape and length of the film while not attached to the tube or battery. If these measurements are compared and the length of the film while attached to the tube or battery is longer than the length of the film while not attached to the tube or battery, the film can be said to be stretched while attached to the tube or battery. Furthermore, if these measurements are compared and the degree to which the center of the film while attached to the tube or battery is narrower than the end portions of the film while not attached to the tube or battery is greater than the degree to which the center of the film while attached to the tube or battery is narrower than the end portions of the film while not attached to the tube or battery (including cases where the center of the film while not attached to the tube or battery is not narrower than the end portions), the film can be said to be necked while attached to the tube or battery.

[0128] The present invention has the following configuration.

[0129] (1) A sensor comprising: a flexible film whose electrical properties change with deformation; and an adhesive member that fixes the film to a tube so that the film conforms to the side of the tube; wherein the film is stretched from its natural length and is constricted while fixed to the tube.

[0130] (2) The sensor according to (1), wherein the film has a first main surface and a second main surface, and the film is a piezoelectric film that generates a potential difference between the first main surface and the second main surface when deformed.

[0131] (3) The sensor according to (1) or (2), wherein the film has a rectangular shape with long and short sides in a plan view when in its natural length, and the film is stretched and constricted in the direction in which the long sides extend when fixed to the tube.

[0132] (4) A sensor described in any one of (1) to (3), wherein the film has a rectangular shape with long and short sides when viewed in a plane when in its natural length, and when the film is fixed to the tube, the direction in which the long sides extend coincides with the circumferential direction centered on the central axis of the tube.

[0133] (5) A sensor described in any one of (1) to (3), wherein the film has a rectangular shape with long and short sides when viewed in a plane when in its natural length, and when the film is fixed to the tube, the direction in which the long sides extend coincides with the axial direction in which the central axis of the tube extends.

[0134] (6) The sensor according to any one of (1) to (3), wherein the film is spirally wrapped around the tube in a state where the film is fixed to the tube.

[0135] (7) The sensor according to any one of (1) to (6), wherein the tube is flexible, and the film, when fixed to the tube, is provided on the tube over at least half the circumference of the tube centered on the central axis of the tube.

[0136] (8) The sensor according to any one of (1) to (7), wherein the film is provided on the pipe around the entire circumference of the pipe centered on the central axis of the pipe when the film is fixed to the pipe.

[0137] (9) A sensor described in any one of (1) to (8), wherein the film, when in its natural length, has a rectangular shape with long and short sides when viewed in a plane, the film is uniaxially stretched and has piezoelectricity in which the molecules are oriented in an orientation direction, and when the film is unfolded in a plane, the orientation direction forms an angle of 45 degrees with respect to each of the directions in which the long sides and the short sides extend.

[0138] (10) A sensor unit comprising: the sensor according to any one of (1) to (9); and a protective member, wherein the film has a first main surface, and the protective member covers the first main surface.

[0139] (11) The sensor unit described in (10), wherein the protective member is cylindrical, and when the film is fixed to the tube, the protective member is provided on the tube around the entire circumference of the tube, centered on the central axis of the tube.

[0140] (12) A sensor comprising: a flexible film whose electrical characteristics change when deformed; and an adhesive member that fixes the film to the battery so that the film fits along the side of the battery, wherein the film is stretched from its natural length and is constricted when fixed to the battery.

[0141] (13) The sensor according to (12), wherein the film has a first main surface and a second main surface, and the film is a piezoelectric film that generates a potential difference between the first main surface and the second main surface when deformed.

[0142] (14) The sensor according to (12), wherein the film includes a strain gauge whose electrical resistance value changes with deformation.

[0143] (15) The sensor according to any one of (12) to (14), wherein the film has a rectangular shape with long sides and short sides in a plan view when in a natural length state, and the film is stretched and constricted in the direction in which the long sides extend when fixed to the battery.

[0144] (16) The sensor according to any one of (12) to (15), wherein the film is spirally wound around the battery in a state where the film is fixed to the battery.

[0145] (17) The sensor according to any one of (12) to (16), further comprising a flexible insulating substrate, wherein the insulating substrate is along a side surface of the battery when the film is fixed to the battery.

[0146] (18) A method for attaching a sensor to a tube or a battery, the sensor having a flexible film whose physical properties change with deformation, the method comprising: stretching the film from its natural length, and attaching the sensor to the tube or the battery in a state where the film is constricted.

[0147] 1, 1a to 1d: Sensor 2: FPC 3: First electrode 4: Film 5: Second electrode 6: First adhesive member 7: Second adhesive member 10, 10a: Sensor unit 11: Protective member 11a: First protective member 11b: Second protective member 20: Electronic device 21: Housing 22: Head 23: Battery 100: Tube 101: Fluid A1: First region A2: Second region CA10, CA100: Central axis DIRA1: First axial direction DIRA2: Second axial direction DIRC1: First circumferential direction DIRC2: Second circumferential direction IS100, IS11: Inner surface OD: Orientation direction OS100, OS11: Outer surface OS23: Side surface S1: First main surface S2: Second main surface Vs: Voltage signal Vspp: Peak-to-peak value

Claims

1. A sensor comprising: a flexible film whose electrical properties change when deformed; and an adhesive member that fixes the film to a tube so that the film conforms to the side of the tube, wherein the film is stretched and constricted when fixed to the tube compared to when not fixed to the tube.

2. The sensor according to claim 1, wherein the film has a first main surface and a second main surface, and the film is a piezoelectric film that generates a potential difference between the first main surface and the second main surface when deformed.

3. A sensor as claimed in claim 1 or claim 2, wherein the film has a rectangular shape with long and short sides in plan view when not fixed to the tube, and the film is stretched and constricted in the direction of the long sides when fixed to the tube.

4. A sensor as claimed in any one of claims 1 to 3, wherein the film has a rectangular shape with long and short sides in plan view when not fixed to the tube, and when the film is fixed to the tube, the direction in which the long sides extend coincides with the circumferential direction centered on the central axis of the tube.

5. A sensor as claimed in any one of claims 1 to 3, wherein the film has a rectangular shape with long and short sides in plan view when not fixed to the tube, and when the film is fixed to the tube, the direction in which the long sides extend coincides with the axial direction in which the central axis of the tube extends.

6. A sensor according to any one of claims 1 to 3, wherein the film is spirally wrapped around the tube while being fixed to the tube.

7. A sensor according to any one of claims 1 to 6, wherein the tube is flexible, and the film, when fixed to the tube, is provided on the tube over at least half the circumference of the tube centered on the central axis of the tube.

8. A sensor according to any one of claims 1 to 7, wherein the film is provided on the pipe around the entire circumference of the pipe, centered on the central axis of the pipe, when fixed to the pipe.

9. A sensor as described in any one of claims 1 to 8, wherein the film has a rectangular shape with long and short sides in a planar view when not fixed to the tube, the film is uniaxially stretched and has piezoelectric properties in which molecules are oriented in an orientation direction, and when the film is unfolded in a plane, the orientation direction forms an angle of 45 degrees with each of the directions in which the long sides and the short sides extend.

10. A sensor unit comprising: a sensor according to any one of claims 1 to 9; and a protective member, wherein the film has a first main surface, and the protective member covers the first main surface.

11. The sensor unit described in claim 10, wherein the protective member is cylindrical, and when the film is fixed to the tube, the protective member is provided on the tube around the entire circumference of the tube, centered on the central axis of the tube.

12. A pipe with a sensor, comprising: a sensor according to any one of claims 1 to 9; and the pipe.

13. A pipe with a sensor unit, comprising: the sensor unit according to claim 10 or 11; and the pipe.

14. A sensor comprising: a flexible film whose electrical properties change when deformed; and an adhesive member that fixes the film to the battery so that the film fits along the side of the battery, wherein the film is stretched and narrowed when fixed to the battery compared to when not fixed to the battery.

15. The sensor according to claim 14, wherein the film has a first main surface and a second main surface, and the film is a piezoelectric film that generates a potential difference between the first main surface and the second main surface when deformed.

16. The sensor according to claim 14, wherein the film includes a strain gauge whose electrical resistance changes with deformation.

17. A sensor as described in any one of claims 14 to 16, wherein the film has a rectangular shape with long and short sides in a plan view when not fixed to the battery, and the film is stretched and constricted in the direction in which the long sides extend when fixed to the battery.

18. A sensor according to any one of claims 14 to 17, wherein the film is spirally wrapped around the battery in a state where it is fixed to the battery.

19. The sensor according to any one of claims 14 to 18, further comprising a flexible insulating substrate, wherein the insulating substrate conforms to the side surface of the battery when the film is fixed to the battery.

20. A method for attaching a sensor having a flexible film whose physical properties change with deformation to a tube or a battery, comprising stretching the film and attaching the sensor to the tube or the battery in a constricted state.

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