WO2020008939A1 - Strain sensor and tensile property measurement method - Google Patents

Strain sensor and tensile property measurement method Download PDF

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Publication number
WO2020008939A1
WO2020008939A1 PCT/JP2019/025029 JP2019025029W WO2020008939A1 WO 2020008939 A1 WO2020008939 A1 WO 2020008939A1 JP 2019025029 W JP2019025029 W JP 2019025029W WO 2020008939 A1 WO2020008939 A1 WO 2020008939A1
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WIPO (PCT)
Prior art keywords
sensor
strain sensor
strain
base plate
sensor element
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Application number
PCT/JP2019/025029
Other languages
French (fr)
Japanese (ja)
Inventor
智彦 樋上
信宏 森山
Original Assignee
オムロン株式会社
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Filing date
Publication date
Priority claimed from JP2018128866A external-priority patent/JP7112901B2/en
Priority claimed from JP2018128867A external-priority patent/JP7001008B2/en
Application filed by オムロン株式会社 filed Critical オムロン株式会社
Priority to CN201980038404.0A priority Critical patent/CN112236657A/en
Publication of WO2020008939A1 publication Critical patent/WO2020008939A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/857—Macromolecular compositions

Definitions

  • the present invention relates to a technique for measuring a strain generated in an object.
  • a strain sensor is a sensor used for measuring a strain generated in an object.
  • a strain sensor measures the amount of strain generated in various types of structures such as bridges and buildings, and monitors (diagnoses) the state of the structure (the state of damage or the like). (For example, see Patent Document 1).
  • the strain sensor has a configuration using a sensor element in which electrodes are formed on both sides of a piezoelectric film. When distortion occurs, the piezoelectric film generates an electric charge corresponding to the distortion. In the sensor element, a voltage is generated between the electrodes formed on both surfaces of the piezoelectric film according to the electric charge generated in the piezoelectric film.
  • the strain sensor is used not only for measuring the above-mentioned structures such as bridges and buildings, but also for measuring the amount of strain generated in a component (for example, a robot arm) of an industrial machine or the like.
  • strain sensors have variations in output sensitivity characteristics.
  • the strain sensors have individual differences in output sensitivity characteristics.
  • the output sensitivity characteristic is a relationship between the amount of distortion and the output (measurement signal).
  • the piezoelectric constant d 31 piezoelectric constant d 31 in the stretching direction
  • the stretching direction of the piezoelectric film is a direction orthogonal to the thickness direction of the piezoelectric film.
  • the conventional strain sensor disclosed in Patent Document 1 or the like has a shape in which it is difficult to apply a force in the stretching direction of the piezoelectric film in a formed state. Therefore, based on the measurement result of the stretching direction of the piezoelectric constant d 31 measured for piezoelectric films sampled had established the output sensitivity characteristic of the strain sensor. That is, the output sensitivity characteristics of the strain sensors used are those estimated on a lot basis, and were not actually measured for individual strain sensors. Therefore, the strain sensor has a deviation between the actual output sensitivity characteristic and the determined output sensitivity characteristic, and this deviation may affect the diagnosis of the state of the structure using the strain sensor. .
  • the measurement of the polarization direction of the piezoelectric constant d 33 utilizes the weight or the like, by the action of load in the thickness direction of the piezoelectric film, relatively easy to measure.
  • the polarization direction is the thickness direction of the piezoelectric film.
  • An object of the present invention is to provide a technique capable of easily measuring output sensitivity characteristics.
  • the strain sensor of the present invention has the following configuration to achieve the above object.
  • the strain sensor has a structure in which a sensor element formed in a film shape is laminated on one surface of a plate-shaped base plate.
  • the sensor element has a piezoelectric film and electrodes laminated on both sides of the piezoelectric film.
  • the base plate has one surface formed so that the stacked sensor elements do not protrude outside, and furthermore, the sensor elements are provided at both ends in the pulling direction parallel to the one surface. Has a chuck portion that is not laminated.
  • the chuck portions provided at both ends of the base plate are held, and the output of the strain sensor is measured while changing the magnitude of the tensile force applied in the longitudinal direction of the strain sensor, thereby obtaining the strain sensor.
  • Output sensitivity characteristics can be measured. That is, the output sensitivity characteristics of the strain sensor can be measured accurately and relatively easily. Therefore, the strain amount of the detection target member can be accurately measured using the strain sensor.
  • the strain sensor may have a configuration in which an output line of the sensor element is electrically connected and an output circuit that outputs a signal corresponding to the output of the sensor element is provided.
  • the output sensitivity characteristics including the electrical characteristics of the output circuit are measured. Measurement can be performed.
  • This output circuit may be attached to one surface of the base plate, or may be attached to a member other than the base plate.
  • the output circuit is mounted on one surface of the base plate, it is preferable to provide a circuit cover that covers the output circuit.
  • the output sensitivity characteristics of the strain sensor can be measured relatively easily.
  • FIG. 1A and 1B are schematic diagrams of a strain sensor.
  • FIG. 3 is a schematic diagram illustrating a configuration of a sensor element. It is a figure explaining the example of use of a strain sensor. It is a schematic view of a measuring device for measuring the piezoelectric constant d 31 of the strain sensor.
  • FIG. 4 is a schematic view of a strain sensor according to another example.
  • FIG. 4 is a schematic view of a strain sensor according to another example.
  • FIG. 4 is a schematic view of a strain sensor according to another example.
  • 8A and 8B are schematic diagrams of a strain sensor according to another example.
  • FIG. 3 is a circuit diagram illustrating an output circuit.
  • FIG. 4 is a schematic view of a strain sensor according to another example.
  • FIG. 3 is a circuit diagram illustrating an output circuit.
  • FIG. 9 is a circuit diagram showing an output circuit according to another example.
  • FIG. 9 is a circuit diagram showing an output circuit according to another example.
  • FIG. 9 is a circuit diagram showing an output circuit according to another example.
  • FIG. 9 is a circuit diagram showing an output circuit according to another example.
  • FIG. 9 is a circuit diagram showing an output circuit according to another example.
  • FIG. 9 is a circuit diagram showing an output circuit according to another example.
  • FIG. 3 is a block diagram illustrating a configuration of a main part of a sensor node. It is a conceptual diagram which shows the example which attaches a sensor to the bridge which diagnoses a state.
  • FIG. 1 is a schematic diagram of a strain sensor according to this example. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along the line AA shown in FIG. As shown in FIG. 1A, the strain sensor 1 according to this example includes a base plate 10, a sensor element 20, a sensor cover 30, a terminal cover 40, an output terminal 45, and an output cable 50.
  • the base plate 10 is a plate-like member formed of an insulating material.
  • the base plate 10 is, for example, a resin substrate made of polycarbonate.
  • the thickness of the base plate 10 is about 1 mm.
  • the base plate 10 has a rectangular lamination surface on which the sensor elements 20 are laminated.
  • the lamination surface is one surface orthogonal to the thickness direction of the base plate 10 (the vertical direction in FIG. 1B). Further, in this example, the direction along the long side (the left-right direction in FIGS. 1A and 1B) along the lamination surface of the base plate 10 is referred to as the longitudinal direction, and the direction along the short side (FIG. 1A). The vertical direction) is called the width direction.
  • the thickness of the sensor element 20 is several tens ⁇ m, which is thinner than the base plate 10.
  • the planar shape of the base plate 10 is not limited to a rectangular shape, and may be, for example, a shape in which a corner shape is formed in an arc shape (a shape in which a corner is rounded), or a corner whose angle is not 90 degrees. May be used.
  • the sensor element 20 is stacked on the stacking surface of the base plate 10.
  • the sensor element 20 is attached to the laminated surface of the base plate 10 using an adhesive, a double-sided tape, or the like.
  • the sensor element 20 has a size that does not protrude outside the base plate 10.
  • the base plate 10 is formed such that the size of the stacking surface is such that the stacked sensor elements 20 do not protrude outside. That is, the length in the width direction of the sensor element 20 is less than the length in the width direction of the base plate 10, and the length in the longitudinal direction of the sensor element 20 is less than the length in the longitudinal direction of the base plate 10. .
  • FIG. 2 is a schematic diagram showing the configuration of the sensor element.
  • the sensor element 20 is formed in a film shape and has a piezoelectric effect.
  • the sensor element 20 is a film-shaped element in which a protective film 23a, an electrode 22a, a piezoelectric film 21, an electrode 22b, and a protective film 23b are laminated in this order.
  • the piezoelectric film 21 is formed by, for example, forming a plastic PVDF (Polyvinylidene fluoride) having a piezoelectric effect into a film shape.
  • the electrodes 22 a and 22 b are stacked so as to sandwich the piezoelectric film 21.
  • the electrodes 22a and 22b are formed, for example, by silver ink screen printing.
  • protective films 23a and 23b are laminated so as to sandwich the electrode 22a, the piezoelectric film 21, and the electrode 22b which are laminated in this order.
  • the protective films 23a and 23b are thin acrylic films and suppress oxidation of the surfaces of the electrodes 22a and 22b.
  • the protective films 23a and 23b are large enough to cover the surfaces of the electrodes 22a and 22b.
  • Output lines 24a and 24b are connected to the electrodes 22a and 22b, respectively.
  • the other ends of the output lines 24a and 24b that are not connected to the electrodes 22a and 22b are connected to an output terminal 45 formed inside the terminal cover 40.
  • the sensor element 20 When distortion (deformation) occurs in the piezoelectric film 21, the sensor element 20 outputs a voltage corresponding to the distortion to the output lines 24a and 24b. Since the sensor element 20 has already been put to practical use, a detailed description thereof will be omitted here.
  • the sensor cover 30 is attached so as to cover the sensor elements 20 stacked on the base plate 10.
  • the sensor cover 30 is a waterproof and airtight single-sided adhesive tape (so-called all-sky tape).
  • the sensor cover 30 suppresses deformation, discoloration, deterioration, and the like of the sensor element 20.
  • the strain sensor 1 has a terminal cover 40 provided on one end side of the sensor element 20 in the longitudinal direction of the base plate 10.
  • the terminal cover 40 is provided on the side from which the output lines 24a and 24b of the sensor element 20 are drawn out.
  • the terminal cover 40 is a molded product using, for example, a polycarbonate resin as a raw material.
  • the terminal cover 40 has a rectangular parallelepiped outer shape and a box shape having a hollow space. The length in the width direction of the terminal cover 40 is shorter than the length in the width direction of the base plate 10.
  • the terminal cover 40 is mounted so that the opening surface faces the laminated surface of the base plate 10, and the output terminal 45 to which the output lines 24 a and 24 b are connected is mounted in the space inside the terminal cover 40. .
  • An output cable 50 is connected to the output terminal 45.
  • the output cable 50 is drawn out through a cable drawing hole formed on the side surface of the terminal cover 40.
  • the terminal cover 40 is attached to the base plate 10 using an adhesive or the like.
  • the resin 41 is filled in a space inside the terminal cover 40 attached to the base plate 10.
  • the strain sensor 1 has a sensor element 20 and a terminal cover 40 arranged side by side in the longitudinal direction of the base plate 10. Further, the strain sensor 1 has a shape in which the sensor elements 20 and the terminal covers 40 are not provided at both ends in the longitudinal direction of the base plate 10 and the chuck portions 10a and 10b are provided. In the chuck portions 10a and 10b, the base plate 10 is exposed.
  • the strain sensor 1 As shown in FIG. 3, the strain sensor 1 according to this example is used by being attached to a detection target member for detecting strain using an adhesive.
  • a surface of the base plate 10 where the sensor element 20 and the terminal cover 40 are not provided (here, referred to as an attachment surface) is attached to a detection target member.
  • the mounting surface is a surface facing the lamination surface.
  • the detection target member is a steel material of a bridge which is a structure, a wall surface of a building which is a structure, an arm of a robot, or the like.
  • the base plate 10 preferably has a Young's modulus Y larger than the Young's modulus Z of the sensor element 20 and smaller than the Young's modulus X of the detection target member to which the strain sensor 1 is attached (Z ⁇ Y ⁇ X). preferable.
  • the strain sensor 1 is attached to a detection target member for detecting strain with an adhesive or the like. Specifically, in the strain sensor 1, an adhesive is applied to a mounting surface of the base plate 10 or a surface of the detection target member, and is attached to the detection target member.
  • the strain sensor 1 has a certain degree of hardness due to the base plate 10. Further, in order to mount the strain sensor 1, there is no need to process the detection target member. Accordingly, the strain sensor 1 can be easily attached to an existing structure.
  • the strain sensor 1 may be affixed to a detection target member for detecting strain with a double-sided tape.
  • the strain sensor 1 covers the sensor element 20 with the sensor cover 30, the influence of the external environment (ultraviolet rays, rain, etc.) on the sensor element 20 is suppressed. That is, in the strain sensor 1, the sensor element 20 is provided with weather resistance by the sensor cover 30, so that the deterioration rate of the strain sensor 1 (sensor element 20) can be suppressed.
  • the strain sensor 1 since the base plate 10 is located between the attached detection target member and the sensor element 20, deterioration of the sensor element 20 due to rainwater or the like leaking from the detection target member can be suppressed. .
  • the Young's modulus Y of the base plate 10 is larger than the Young's modulus Z of the sensor element 20 and smaller than the Young's modulus X of the detection target member to which the strain sensor 1 is attached (X> Y> Z). ), It is possible to accurately detect the distortion of the detection target member. This will be described below.
  • X ⁇ Y 0 ⁇ (X / Y) ⁇ 1. Therefore, the strain ⁇ 2 of the base plate 10 is smaller than the strain ⁇ 1 of the detection target member.
  • the strain ⁇ 3 of the sensor element 20 has a magnitude corresponding to the strain ⁇ 2 of the base plate 10, it is smaller than the strain ⁇ 1 of the detection target member. Therefore, if the relationship between the Young's modulus Y of the base plate 10 and the Young's modulus X of the detection target member to which the strain sensor 1 is attached is X ⁇ Y, the strain ⁇ 1 of the detection target member Detection accuracy decreases.
  • the strain sensor 1 sets the relationship between the Young's modulus Y of the base plate 10 and the Young's modulus X of the detection target member to which the strain sensor 1 is attached to X> Y, whereby the strain ⁇ 1 ⁇ of the detection target member is obtained. Since the strain ⁇ 2 of the base plate 10 is obtained, the detection accuracy of the strain ⁇ 1 of the detection target member is improved.
  • the strain sensor 1 makes the Young's modulus Y of the base plate 10 larger than the Young's modulus Z of the sensor element 20, and thereby the base plate 10 has the same structure as the above-described relationship between the detection target member and the base plate 10.
  • the strain ⁇ 2 ⁇ the strain ⁇ 3 of the sensor element 20. That is, the strain ⁇ 1 of the detection target member ⁇ ⁇ the strain ⁇ 3 of the sensor element 20.
  • the detection accuracy of the strain ⁇ 1 of the detection target member can be improved.
  • the relationship between the Young's modulus X of the detection target member, the Young's modulus Y of the base plate 10, and the Young's modulus Z of the sensor element 20 improves the detection accuracy of the strain ⁇ 1 of the detection target member. It is a preferable relationship in making the relationship, and it does not mean that a material that does not satisfy this relationship is not included in the present invention.
  • the base plate 10 of the strain sensor 1 is formed of an insulating material, leakage of electric charges generated in the sensor element 20 and inflow of electric charges from the outside into the sensor element 20 can be suppressed.
  • the strain sensor 1 according to this example (here, referred to the stretching direction.) Direction perpendicular to the thickness direction of the piezoelectric film 21 for measurement of the piezoelectric constant d 31 in the describing.
  • the piezoelectric constant d 31 measured as the output sensitivity of the strain sensor 1.
  • the strain sensor 1 according to this example does not include the sensor element 20 and the terminal cover 40 at both ends in the longitudinal direction, and the chuck portion 10 a in which the base plate 10 is exposed. , 10b.
  • FIG. 4 is a schematic view of a measuring device for measuring the piezoelectric constant d 31 of the strain sensor.
  • the measuring device 100 has an upper end holding portion 101, a lower end holding portion 102, and a slide member 103.
  • the upper end holding portion 101 has a structure for holding and holding the chuck portion 10 a located at one end in the longitudinal direction of the strain sensor 1.
  • the lower end holding portion 102 has a structure for holding and holding the chuck portion 10b located at the other end of the strain sensor 1 in the longitudinal direction.
  • the holding part where the upper end holding part 101 holds one end in the longitudinal direction of the strain sensor 1 and the holding part where the lower end holding part 102 holds the other end in the longitudinal direction of the strain sensor 1 face each other. I have.
  • the slide member 103 is slidably attached to the lower end holding portion 102 (in the vertical direction in FIG. 4) by a slide mechanism (not shown). Further, the upper end holding part 101 is attached to the slide member 103. In other words, the upper end holding portion 101 slides in the direction in which the upper end holding portion 101 comes into contact with and separates from the lower end holding portion 102 as the slide member 103 slides.
  • the upper end holding portion 101 holds the chuck portion 10a and the lower end holding portion 102 holds the chuck portion 10b, but the upper end holding portion 101 holds the chuck portion 10b and the lower end holding portion 102 holds the chuck portion 10b.
  • the part 10a may be held.
  • each strain sensor 1, enabling the measurement is relatively simple in piezoelectric constant d 31 of the strain sensor 1.
  • the piezoelectric constant d 31 measured for the strain sensor 1 is used, it is possible to determine the output sensitivity characteristic of the strain sensor 1. Therefore, it is possible to improve the measurement accuracy of the strain amount of the detection target member.
  • the strain sensor 1 when the measurement of the piezoelectric constant d 31, the sensor element 20 by the measuring device 100, and since the terminal cover 40 is not held, nor damaged.
  • the measuring device 100 is configured to pull the strain sensor 1 in the vertical direction.
  • the direction in which the strain sensor 1 is pulled may be the longitudinal direction of the strain sensor 1.
  • the measuring device 100 may be configured to pull the set strain sensor 1 in the horizontal direction.
  • FIG. 5 is a plan view (a diagram corresponding to FIG. 1A) showing a strain sensor according to another example (first modification).
  • the strain sensor 1A according to this example is different from the above example in that the center lines 11a and 11b are marked on the chuck portions 10a and 10b.
  • the center lines 11a and 11b are lines extending in the longitudinal direction of the strain sensor 1A, and are marked at substantially the center in the width direction of the strain sensor 1A.
  • the strain sensor 1A When the strain sensor 1A is set on the measuring instrument 100 shown in FIG. 4, by using the center lines 11a and 11b as reference lines, the strain sensor 1A can be set upright.
  • FIG. 6 is a plan view (a diagram corresponding to FIG. 1A) showing a strain sensor according to another example (a second modification).
  • the strain sensor 1B according to this example has a shape in which the widths of the chuck portions 10a and 10b located at both ends in the longitudinal direction are narrower than other portions (the portions where the sensor element 20 and the terminal cover 40 are attached). is there.
  • the chuck 10a and the chuck 10b have the same width.
  • FIG. 7 is a plan view (a diagram corresponding to FIG. 1A) showing a strain sensor according to another example (third modification).
  • the strain sensor 1C according to this example has a shape in which the widths of the chuck portions 10a and 10b located at both ends in the longitudinal direction are wider than other portions (the portions where the sensor element 20 and the terminal cover 40 are attached). is there.
  • the chuck 10a and the chuck 10b have the same width.
  • FIG. 8 is a schematic view of a strain sensor according to another example (fourth modification). 8A is a plan view, and FIG. 8B is a cross-sectional view taken along the line AA shown in FIG.
  • the strain sensor 1D according to this example has a configuration in which the output terminal 45 of the above-described example is replaced with an output circuit 46.
  • the output lines 24a and 24b of the sensor element 20 are connected to the input terminals of the output circuit 46 attached to the inside of the terminal cover 40 at the other end not connected to the electrodes 22a and 22b.
  • the output cable 50 is connected to an output terminal of the output circuit 46.
  • FIG. 9 is a circuit diagram showing an output circuit.
  • the output circuit 46 shown in FIG. 9 is a charge amplifier circuit that outputs, as a measurement signal, a voltage corresponding to the charge generated in the sensor element 20 according to the amount of distortion of the sensor element 20.
  • the output of the output circuit 46 is a measurement signal of the strain sensor 1.
  • the output circuit 46 has a capacitor Cf connected between the negative input terminal and the output terminal of the amplifier Amp for charging the electric charge generated in the sensor element 20. Further, the output circuit 46 connects a resistor R for releasing a leak current in parallel with the capacitor Cf.
  • the output circuit 46 outputs a voltage V according to the charge Q charged in the capacitor Cf.
  • Out (+) and out ( ⁇ ) shown in FIG. 9 are output terminals of the output circuit 46, and one end of the output cable 50 is connected to the output terminal of the output circuit 46.
  • the capacitor Cf is charged with electric charge generated by the sensor element 20 (electric charge generated according to the amount of distortion of the sensor element 20). That is.
  • the output circuit 46 outputs a voltage according to the amount of distortion of the sensor element 20.
  • the output circuit 46 is attached to the base plate 10 and covered by the terminal cover 40.
  • the strain sensor 1D is also used by attaching it to a detection target member for detecting strain using an adhesive or the like.
  • the output circuit 46 is covered by the terminal cover 40, and the space inside the terminal cover 40 is filled with the resin 41, so that the output circuit 46 is not affected by the external environment (ultraviolet rays, rain, etc.). Can be suppressed. That is, in the strain sensor 1D, the output circuit 46 is provided with weather resistance by the terminal cover 40 and the resin 41, so that the deterioration speed of the output circuit 46 can be suppressed.
  • the strain sensor 1D the deterioration of the sensor element 20 and the output circuit 46 due to rainwater or the like leaking from the detection target member is suppressed by the base plate 10.
  • the strain sensor 1D also has a Young's modulus Y of the base plate 10, a Young's modulus Z of the sensor element 20, and a Young's modulus X of the detection target member, where X> Y> Z, as in the above example.
  • the distortion of the detection target member can be accurately detected.
  • the output sensitivity characteristic referred to in this example is a relationship between a distortion amount of the piezoelectric film 21 and a measurement signal output from the output circuit 46.
  • the strain sensor 1D according to this example also has chuck portions 10a and 10b in which the sensor element 20 and the terminal cover 40 are not provided at both ends in the longitudinal direction and the base plate 10 is exposed.
  • the measurement of the output sensitivity characteristic is performed by the measuring device 100 shown in FIG.
  • the output sensitivity characteristics measured for the strain sensor 1D include the characteristics of the piezoelectric film 21, the electrical characteristics of the circuit components and the like constituting the output circuit 46, and the connection relating to the electrical connection between the sensor element 20 and the output circuit 46, and the like. It is affected by characteristics. Therefore, measurement (sensing) of the strain amount of the detection target member by the strain sensor 1D can be performed using the output sensitivity characteristics actually measured for the strain sensor 1D to be used.
  • strain sensor 1 characteristics of the piezoelectric film 21, electric characteristics of circuit components and the like constituting the output circuit 46, connection characteristics related to electric connection between the sensor element 20 and the output circuit 46, and the like. Without being affected, it is possible to accurately measure the amount of strain generated in various types of structures such as bridges and buildings. Thereby, the diagnosis of the state of the structure using the strain sensor 1D can be performed more appropriately.
  • the strain sensor 1D is not damaged.
  • the output circuit 46 is configured to be mounted on the base plate 10, but may be configured as shown in FIG. In the strain sensor 1E shown in FIG. 10, the output circuit 46 described above is not mounted inside the terminal cover 40.
  • the strain sensor 1E according to this example has a configuration in which the output circuit 46 is mounted inside a storage case 47 formed separately from the base plate 10.
  • the storage case 47 is a molded product made of, for example, a polycarbonate resin as a raw material. Inside the storage case 47, a space for storing the output circuit 46 is formed.
  • connection cable 51 electrically connects the output lines 24a and 24b of the sensor element 20 and the input terminals of the output circuit 46.
  • the output cable 52 is electrically connected to the output terminal of the output circuit 46 as in the above example.
  • the output terminal 45 described in the above example may be attached to the base plate 10.
  • the output terminal 45 is attached to the base plate 10 so as to be located inside the terminal cover 40.
  • the storage case 47 housing the output circuit 46 may or may not be filled with resin.
  • strain sensor 1E shown in FIG. 10 measures the voltage of the connection cable 51 in addition to the measurement of the voltage of the output cable 52 in the measurement of the output sensitivity characteristics described above, so that the piezoelectric film 21 in the stretching direction is measured. It can be measured for piezoelectric constant d 31.
  • the base plate 10 has the shape shown in FIG. 1, but may have the shape shown in FIG. 5, FIG. 6, or FIG.
  • the output circuit 46 is not limited to the circuit shown in FIG. 9 and may be constituted by another circuit.
  • 11 to 16 are diagrams each showing an output circuit according to another example. The output circuits 46a to 46f shown in FIGS. 11 to 16 will be briefly described.
  • a voltage corresponding to the strain generated in the sensor element 20 (piezoelectric film 21) is applied to both ends of the resistor R1.
  • the output circuit 46a is a known voltage follower, and outputs a voltage applied across the resistor R1.
  • the output circuit 46b shown in FIG. 12 a voltage corresponding to the strain generated in the sensor element 20 (piezoelectric film 21) is applied across the resistor R2.
  • the output circuit 46b is an amplifier circuit that amplifies the voltage applied to both ends of the resistor R1 by ((Ra + Rb) / Ra) times and outputs the amplified voltage.
  • the output circuits 46c and 46d shown in FIGS. 13 and 14 are circuits using FETs.
  • the output circuit 46c shown in FIG. 13 is a common drain circuit, and outputs a voltage applied to both ends of the resistor R3.
  • a voltage corresponding to the strain generated in the sensor element 20 (piezoelectric film 21) is applied to both ends of the resistor R3.
  • the output circuit 46d shown in FIG. 14 is a common source circuit, and amplifies the voltage applied across the resistor R4 by (Rd / Re) times and outputs the amplified voltage.
  • a voltage corresponding to the strain generated in the sensor element 20 (piezoelectric film 21) is applied to both ends of the resistor R4.
  • the output circuit 46e shown in FIG. 15 is a trigger circuit that outputs a high level when a voltage corresponding to a strain generated in the sensor element 20 (piezoelectric film 21) exceeds a set voltage.
  • This set voltage can be set by changing the resistance value of the variable resistor VR.
  • the output circuit 46f shown in FIG. 16 generates the voltage at the sensor element 20 (piezoelectric film 21) when the voltage generated at the sensor element 20 (piezoelectric film 21) is equal to or higher than the voltage V applied to the resistor Rf. This is a circuit that outputs a voltage.
  • the power supply voltage required to operate the above-described output circuits 46, 46a to 46f may be supplied by a battery or the like provided in this output circuit, or may be an external device (for example, a sensor node 110).
  • the supply of the power supply voltage from the external device to the output circuits 46 and 46a to 46f may be performed using the output cables 50 and 52.
  • FIG. 17 is a diagram illustrating a configuration of a main part of the sensor node.
  • the sensor node 110 measures various physical quantities used for the diagnosis of the structure whose state is to be diagnosed, and outputs the measured physical quantities to a diagnostic device (not shown).
  • the sensor node 110 includes a control unit 111, sensor control circuits 112 to 115, a timer 116, a storage unit 117, a wireless communication unit 118, and a power supply unit 119.
  • the control unit 111 controls the operation of each unit of the sensor node 110 main body.
  • the strain sensor 1 is connected to the sensor control circuit 112. Further, sensors 121 to 123 are connected to the sensor control circuits 113 to 115, respectively.
  • the sensor control circuits 112 to 115 include processing circuits that process detection signals (sensing signals) of the connected strain sensors 1 and sensors 121 to 123 and obtain sensing data (measured physical quantities).
  • the detection signal of the strain sensor 1 is an output signal of the output circuit 46 (or 46a to 46f) described above.
  • the sensor control circuits 112 to 115 include a processing circuit corresponding to the strain sensor 1 to be connected and the sensors 121 to 123. That is, the sensor control circuits 112 to 115 do not always have the same circuit configuration of the processing circuit.
  • the sensors 121 to 123 may be the strain sensors 1 described above, or may include the acceleration of the structure, the displacement of the structure, the vibration frequency of the structure, the temperature around the structure, the humidity around the structure, and the structure. Other types of sensors that sense the amount of infrared rays of an object, the wind speed around a structure, and the like may be used.
  • the sensor node 110 has a configuration in which the strain sensor 1 and the sensors 121 to 123 are connected (a configuration in which four sensors are connected), but the number of connected sensors (ie, The number of sensor control circuits) may be five or more, or three or less. Further, the sensor node 110 may be used in a state where the strain sensor 1 and the sensors 121 to 123 are not connected to some of the sensor control circuits 112 to 115.
  • the timer 116 counts the current date and time.
  • the storage unit 117 stores various setting parameters used during the operation of the sensor node 110 and physical quantities (strain amounts of structures, distortion amounts of structures, and the like) obtained by processing measurement signals input from the connected strain sensors 1 and sensors 121 to 123.
  • the acceleration of the structure, the amount of displacement of the structure, the vibration frequency of the structure, the temperature around the structure, the humidity around the structure, the amount of infrared radiation of the structure, the wind speed around the structure, etc. are temporarily stored.
  • the wireless communication unit 118 controls wireless communication with a device to which various physical quantities of the measured structure are transmitted.
  • the device that is the transmission destination of various physical quantities may be a diagnostic device (not shown) that diagnoses the state of the structure using various physical quantities collected from the plurality of sensor nodes 110.
  • a relay device (not shown) for relaying various physical quantities transmitted / received to / from the diagnostic device may be used.
  • the power supply unit 119 includes a battery 119a.
  • the battery 119a is a drive power supply for the sensor node 110.
  • the power supply unit 119 supplies power required for operation to each unit of the sensor node 110 main body from the battery 119a.
  • the sensor node 110 supplies power to the sensor control circuits 112 to 115 as needed.
  • the power supply unit 119 turns on / off the supply of drive power from the battery 119a to the sensor control circuits 112 to 115 in accordance with an instruction from the control unit 111.
  • the state in which the power supply unit 119 turns off the supply of the drive power to the sensor control circuits 112 to 115 means that the supply of power to the sensor control circuits 112 to 115 is not performed at all. The state may not be performed, but is not limited to this state.
  • the drive power supply stop state referred to here is a state in which the power supply unit 119 is not supplying power necessary for the sensor control circuits 112 to 115 and the connected sensors 121 to 123 to operate properly. is there.
  • the sensor control circuits 112 to 115 and the connected sensors 121 to 123 are used.
  • the state in which the power required to maintain the standby state (sleep state) is supplied is also included in the drive power supply stop state referred to herein.
  • the sensor node 110 has a configuration in which the battery 119a is a driving power source, but may have a configuration in which a commercial power source is a driving power source.
  • the strain sensor 1 and the sensors 121 to 123 are attached to a structure to be measured.
  • the strain sensor 1 is attached to a steel material or the like of a structure to be measured.
  • the structures to be measured are bridges, tunnels, buildings, houses, plant facilities, pipelines, telephone poles, gas supply facilities, water and sewage facilities, archeological sites, and the like.
  • FIG. 18 is a conceptual diagram showing an example of attaching a sensor to a bridge for diagnosing a condition.
  • the bridge shown in FIG. 18 is an elevated road bridge on which an automobile runs.
  • the elevated road bridge is divided into an upper structure and a lower structure.
  • the upper structure includes a floor slab, a main girder, a main structure, a horizontal structure, and the like, and the lower structure includes an abutment, a pier, and the like.
  • the traveling path of the vehicle is formed on a floor slab of the superstructure.
  • a support is provided between the upper structure and the lower structure to absorb vibration of the upper structure and deformation of the upper structure due to a vehicle running on a traveling road (road surface) and suppress a load applied to the lower structure. I have.
  • Substructure piers and abutments are installed on foundations formed underground.
  • the upper side of the bearing is called the upper structure, and the lower side of the bearing is called the lower structure.
  • the strain sensor 1 and the sensors 121 to 123 are mounted at positions where the physical quantity of the type of measurement target can be measured appropriately.
  • FIG. 18 shows an example in which the strain sensor 1 and the sensors 121 to 123 are attached to the upper structure of the bridge, but they may be attached to the lower structure.
  • the sensor node 110 measures the physical quantity by the strain sensor 1 and the sensors 121 to 123.
  • the measurement timing may be a predetermined time or a time interval, or may be a timing that satisfies a predetermined condition (such as temperature).
  • the sensor node 110 stores, in the storage unit 117, measurement data in which physical quantities measured by the strain sensor 1 and the sensors 121 to 123 are associated with measurement times. When a predetermined transmission timing is reached, the sensor node 110 diagnoses measurement data (measured physical quantity stored in the storage unit 117) relating to the physical quantity measured from the previous transmission timing to the current transmission timing. Send to device. At this time, the sensor node 110 has transmitted an identification number for identifying itself.
  • the diagnostic device classifies and collects the measurement data transmitted from each sensor node 110 by the sensor node 110. That is, the diagnostic device collects, for each sensor node 110, various physical quantities measured by the sensor node 110. The diagnostic device diagnoses the state of the bridge for each sensor node 110 using the collected various physical quantities.
  • the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements in an implementation stage without departing from the scope of the invention.
  • Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Further, constituent elements of different embodiments may be appropriately combined.
  • the sensor element (20) has a piezoelectric film (21) and electrodes (22a, 22b) laminated on both sides of the piezoelectric film (21),
  • the base plate (10) is formed such that the one surface is formed in such a size that the stacked sensor elements (20) do not protrude outside, and furthermore, the pulling member is parallel to the one surface.
  • Strain sensor 10 Base plate 10a, 10b: Chuck portion 11a: Center line 20: Sensor element 21: Piezoelectric films 22a, 22b: Electrodes 23a, 23b: Protective film 24a: Output line 30: Sensor cover 40 ... terminal cover 41 ... resin 45 ... output terminals 46 and 46a to 46f ... output circuit 47 ... storage cases 50 and 52 ... output cable 51 ... connection cable 100 ... measuring instrument 101 ... upper end holding part 102 ... lower end holding part 103 ... slide member

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  • Spectroscopy & Molecular Physics (AREA)
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Abstract

In a strain sensor, a sensor element formed in a film shape is laminated on one surface of a plate-shaped base plate. The sensor element comprises a piezoelectric film and electrodes laminated on both sides of the piezoelectric film. The one surface of the base plate is formed to a size such that the laminated sensor element does not protrude outward, and the base plate includes chuck portions on which the sensor element is not laminated at both end portions in the tension direction parallel to the one surface.

Description

ひずみセンサ、および引張特性測定方法Strain sensor and method for measuring tensile properties
　この発明は、物体に生じたひずみを計測する技術に関する。 発 明 The present invention relates to a technique for measuring a strain generated in an object.
　従来、フィルム状に形成した圧電フィルム（ピエゾフィルム）を用いたひずみセンサがあった。ひずみセンサは、物体に生じたひずみの計測に用いるセンサである。例えば、ひずみセンサで、橋梁やビル等の様々な種類の構造物に生じたひずみ量を計測し、その構造物の状態（損傷等にかかる状態）をモニタリング（診断）することが行われている（例えば、特許文献１参照）。 Conventionally, there has been a strain sensor using a piezoelectric film (piezo film) formed in a film shape. A strain sensor is a sensor used for measuring a strain generated in an object. For example, a strain sensor measures the amount of strain generated in various types of structures such as bridges and buildings, and monitors (diagnoses) the state of the structure (the state of damage or the like). (For example, see Patent Document 1).
　ひずみセンサは、圧電フィルムの両面に電極を形成したセンサ素子を用いた構成である。圧電フィルムは、ひずみが生じると、そのひずみに応じた電荷を発生する。センサ素子は、圧電フィルムの両面に形成した電極間に、この圧電フィルムで発生した電荷に応じた電圧が生じる。 The strain sensor has a configuration using a sensor element in which electrodes are formed on both sides of a piezoelectric film. When distortion occurs, the piezoelectric film generates an electric charge corresponding to the distortion. In the sensor element, a voltage is generated between the electrodes formed on both surfaces of the piezoelectric film according to the electric charge generated in the piezoelectric film.
　なお、ひずみセンサは、上述した橋梁やビル等の構造物に限らず、産業機械等の構成要素（例えば、ロボットアーム、）に生じたひずみ量を計測することにも使用されている。 ひ ず み Note that the strain sensor is used not only for measuring the above-mentioned structures such as bridges and buildings, but also for measuring the amount of strain generated in a component (for example, a robot arm) of an industrial machine or the like.
特開２０１７－　　３３７１号公報JP 2017-33771 A
　しかしながら、ひずみセンサは、出力感度特性にばらつきがある。言い換えれば、ひずみセンサは、出力感度特性に個体差がある。ここで言う出力感度特性とは、ひずみ量と、出力（計測信号）との関係である。ひずみセンサ間で、出力感度特性にばらつきが生じる要因の１つに、圧電フィルムの特性である圧電定数ｄ31（延伸方向の圧電定数ｄ31）のばらつきがある。圧電フィルムの延伸方向とは、圧電フィルムの厚さ方向に直交する方向である。 However, strain sensors have variations in output sensitivity characteristics. In other words, the strain sensors have individual differences in output sensitivity characteristics. Here, the output sensitivity characteristic is a relationship between the amount of distortion and the output (measurement signal). Between the strain sensors, one of the factors that variation in the output sensitivity characteristics, there are variations of the piezoelectric constant d 31 (piezoelectric constant d 31 in the stretching direction) which is characteristic of the piezoelectric film. The stretching direction of the piezoelectric film is a direction orthogonal to the thickness direction of the piezoelectric film.
　特許文献１等で示されている従来のひずみセンサは、形成された状態で、圧電フィルムの延伸方向に力を作用させることが困難な形状である。このため、サンプル抽出した圧電フィルムについて測定した延伸方向の圧電定数ｄ31の測定結果に基づいて、ひずみセンサの出力感度特性を定めていた。すなわち、ひずみセンサの出力感度特性は、ロット単位で推定したものを用いており、個々のひずみセンサについて実測したものではなかった。したがって、ひずみセンサは、実際の出力感度特性と、定められた出力感度特性との間にずれがあり、このずれが、ひずみセンサを用いた構造物の状態の診断に影響を与えることがあった。 The conventional strain sensor disclosed in Patent Document 1 or the like has a shape in which it is difficult to apply a force in the stretching direction of the piezoelectric film in a formed state. Therefore, based on the measurement result of the stretching direction of the piezoelectric constant d 31 measured for piezoelectric films sampled had established the output sensitivity characteristic of the strain sensor. That is, the output sensitivity characteristics of the strain sensors used are those estimated on a lot basis, and were not actually measured for individual strain sensors. Therefore, the strain sensor has a deviation between the actual output sensitivity characteristic and the determined output sensitivity characteristic, and this deviation may affect the diagnosis of the state of the structure using the strain sensor. .
　なお、ひずみセンサに対する、分極方向の圧電定数ｄ33の測定は、重り等を利用して、圧電フィルムの厚さ方向に荷重を作用させることにより、比較的簡単に測定できる。分極方向とは、圧電フィルムの厚さ方向である。 Incidentally, for the strain sensor, the measurement of the polarization direction of the piezoelectric constant d 33 utilizes the weight or the like, by the action of load in the thickness direction of the piezoelectric film, relatively easy to measure. The polarization direction is the thickness direction of the piezoelectric film.
　この発明の目的は、出力感度特性の測定が簡単に行える技術を提供することにある。 An object of the present invention is to provide a technique capable of easily measuring output sensitivity characteristics.
　この発明のひずみセンサは、上記目的を達するため、以下のように構成している。 ひ ず み The strain sensor of the present invention has the following configuration to achieve the above object.
　ひずみセンサは、板状のベース板の一方の面に、フィルム状に形成されたセンサ素子を積層した構成である。また、センサ素子は、圧電フィルムと、この圧電フィルムの両面に積層された電極とを有する。また、ベース板は、一方の面を、積層されているセンサ素子が外側にはみ出さない大きさに形成したものであり、さらに、一方の面に平行である引っ張り方向における両端部に、センサ素子が積層されていないチャック部を有する。 The strain sensor has a structure in which a sensor element formed in a film shape is laminated on one surface of a plate-shaped base plate. The sensor element has a piezoelectric film and electrodes laminated on both sides of the piezoelectric film. Further, the base plate has one surface formed so that the stacked sensor elements do not protrude outside, and furthermore, the sensor elements are provided at both ends in the pulling direction parallel to the one surface. Has a chuck portion that is not laminated.
　この構成では、ベース板の両端部に設けたチャック部を保持し、ひずみセンサの長手方向に作用させる引張力の大きさを変化させながら、このひずみセンサの出力を計測することにより、ひずみセンサの出力感度特性を測定することができる。すなわち、ひずみセンサの出力感度特性の測定が精度よく、比較的簡単に行える。したがって、このひずみセンサを利用した検出対象部材のひずみ量の計測が精度よく行える。 In this configuration, the chuck portions provided at both ends of the base plate are held, and the output of the strain sensor is measured while changing the magnitude of the tensile force applied in the longitudinal direction of the strain sensor, thereby obtaining the strain sensor. Output sensitivity characteristics can be measured. That is, the output sensitivity characteristics of the strain sensor can be measured accurately and relatively easily. Therefore, the strain amount of the detection target member can be accurately measured using the strain sensor.
　また、ひずみセンサは、センサ素子の出力ラインが電気的に接続され、当該センサ素子の出力に応じた信号を出力する出力回路を有する構成であってもよい。この場合、上記したように、ひずみセンサの長手方向に作用させる引張力の大きさを変化させながら、この出力回路の出力を計測することにより、出力回路の電気的特性をも含む出力感度特性の測定が行える。 The strain sensor may have a configuration in which an output line of the sensor element is electrically connected and an output circuit that outputs a signal corresponding to the output of the sensor element is provided. In this case, as described above, by measuring the output of this output circuit while changing the magnitude of the tensile force acting in the longitudinal direction of the strain sensor, the output sensitivity characteristics including the electrical characteristics of the output circuit are measured. Measurement can be performed.
　この出力回路は、ベース板の一方の面に取り付けられていてもよいし、ベース板以外の部材に取り付けられていてもよい。また、出力回路を、ベース板の一方の面に取り付ける場合には、この出力回路を覆う回路カバーを設けるのが好ましい。特に、この回路カバーの内部に、樹脂を充填するのがよい。このように構成すれば、ひずみセンサを屋外で使用する場合であっても、雨、紫外線等による出力回路の劣化が抑えられる。 This output circuit may be attached to one surface of the base plate, or may be attached to a member other than the base plate. When the output circuit is mounted on one surface of the base plate, it is preferable to provide a circuit cover that covers the output circuit. In particular, it is preferable to fill the inside of the circuit cover with a resin. With this configuration, even when the strain sensor is used outdoors, deterioration of the output circuit due to rain, ultraviolet rays, or the like can be suppressed.
　この発明によれば、ひずみセンサの出力感度特性を比較的簡単に測定できる。 According to the present invention, the output sensitivity characteristics of the strain sensor can be measured relatively easily.
図１（Ａ）、（Ｂ）は、ひずみセンサの概略図である。1A and 1B are schematic diagrams of a strain sensor. センサ素子の構成を示す概略図である。FIG. 3 is a schematic diagram illustrating a configuration of a sensor element. ひずみセンサの使用例を説明する図である。It is a figure explaining the example of use of a strain sensor. ひずみセンサの圧電定数ｄ31を測定する測定器の概略図である。It is a schematic view of a measuring device for measuring the piezoelectric constant d 31 of the strain sensor. 別の例にかかる、ひずみセンサの概略図である。FIG. 4 is a schematic view of a strain sensor according to another example. 別の例にかかる、ひずみセンサの概略図である。FIG. 4 is a schematic view of a strain sensor according to another example. 別の例にかかる、ひずみセンサの概略図である。FIG. 4 is a schematic view of a strain sensor according to another example. 図８（Ａ）、（Ｂ）は、別の例にかかる、ひずみセンサの概略図である。8A and 8B are schematic diagrams of a strain sensor according to another example. 出力回路を示す回路図である。FIG. 3 is a circuit diagram illustrating an output circuit. 別の例にかかる、ひずみセンサの概略図である。FIG. 4 is a schematic view of a strain sensor according to another example. 別の例にかかる、出力回路を示す回路図である。FIG. 9 is a circuit diagram showing an output circuit according to another example. 別の例にかかる、出力回路を示す回路図である。FIG. 9 is a circuit diagram showing an output circuit according to another example. 別の例にかかる、出力回路を示す回路図である。FIG. 9 is a circuit diagram showing an output circuit according to another example. 別の例にかかる、出力回路を示す回路図である。FIG. 9 is a circuit diagram showing an output circuit according to another example. 別の例にかかる、出力回路を示す回路図である。FIG. 9 is a circuit diagram showing an output circuit according to another example. 別の例にかかる、出力回路を示す回路図である。FIG. 9 is a circuit diagram showing an output circuit according to another example. センサノードの主要部の構成を示すブロック図である。FIG. 3 is a block diagram illustrating a configuration of a main part of a sensor node. 状態を診断する橋梁にセンサを取り付ける例を示す概念図である。It is a conceptual diagram which shows the example which attaches a sensor to the bridge which diagnoses a state.
　以下、この発明の実施形態であるひずみセンサについて説明する。 Hereinafter, a strain sensor according to an embodiment of the present invention will be described.
　＜１．構成例＞
　図１は、この例にかかるひずみセンサの概略図である。図１（Ａ）は、平面図であり、図１（Ｂ）は、図１（Ａ）に示すＡ－Ａ線部の断面図である。この例にかかるひずみセンサ１は、図１（Ａ）に示すように、ベース板１０、センサ素子２０、センサカバー３０、端子カバー４０、出力端子４５、および出力ケーブル５０を備えている。 <1. Configuration Example>
FIG. 1 is a schematic diagram of a strain sensor according to this example. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along the line AA shown in FIG. As shown in FIG. 1A, the strain sensor 1 according to this example includes a base plate 10, a sensor element 20, a sensor cover 30, a terminal cover 40, an output terminal 45, and an output cable 50.
　ベース板１０は、絶縁材料で形成された板状部材である。ベース板１０は、例えばポリカーボネート製の樹脂基板である。ベース板１０の厚さは、１ｍｍ程度である。ベース板１０は、センサ素子２０を積層する積層面が矩形形状である。積層面は、ベース板１０の厚さ方向（図１（Ｂ）における上下方向）に直交する一方の面である。また、この例では、ベース板１０の積層面の長辺に沿う方向（図１（Ａ）、（Ｂ）における左右方向）を長手方向と言い、短辺に沿う方向（図１（Ａ）における上下方向）を幅方向と言う。センサ素子２０の厚さは、数十μｍであり、ベース板１０よりも薄い。 The base plate 10 is a plate-like member formed of an insulating material. The base plate 10 is, for example, a resin substrate made of polycarbonate. The thickness of the base plate 10 is about 1 mm. The base plate 10 has a rectangular lamination surface on which the sensor elements 20 are laminated. The lamination surface is one surface orthogonal to the thickness direction of the base plate 10 (the vertical direction in FIG. 1B). Further, in this example, the direction along the long side (the left-right direction in FIGS. 1A and 1B) along the lamination surface of the base plate 10 is referred to as the longitudinal direction, and the direction along the short side (FIG. 1A). The vertical direction) is called the width direction. The thickness of the sensor element 20 is several tens μm, which is thinner than the base plate 10.
　なお、ベース板１０の平面形状は、矩形形状に限らず、例えば角の形状を円弧状に形成した形状（角に丸みを持たせた形状）であってもよいし、角度が９０度でない角を有する形状であってもよい。 The planar shape of the base plate 10 is not limited to a rectangular shape, and may be, for example, a shape in which a corner shape is formed in an arc shape (a shape in which a corner is rounded), or a corner whose angle is not 90 degrees. May be used.
　センサ素子２０は、ベース板１０の積層面に積層されている。センサ素子２０は、接着剤、または両面テープ等を用いて、ベース板１０の積層面に貼り合わせられている。センサ素子２０は、ベース板１０の外側にはみ出さない大きさである。言い換えれば、ベース板１０は、積層面の大きさを、積層されるセンサ素子２０が外側にはみ出さない大きさに形成している。すなわち、センサ素子２０の幅方向の長さは、ベース板１０の幅方向の長さ未満であり、且つセンサ素子２０の長手方向の長さは、ベース板１０の長手方向の長さ未満である。 The sensor element 20 is stacked on the stacking surface of the base plate 10. The sensor element 20 is attached to the laminated surface of the base plate 10 using an adhesive, a double-sided tape, or the like. The sensor element 20 has a size that does not protrude outside the base plate 10. In other words, the base plate 10 is formed such that the size of the stacking surface is such that the stacked sensor elements 20 do not protrude outside. That is, the length in the width direction of the sensor element 20 is less than the length in the width direction of the base plate 10, and the length in the longitudinal direction of the sensor element 20 is less than the length in the longitudinal direction of the base plate 10. .
　図２は、センサ素子の構成を示す概略図である。センサ素子２０は、フィルム状に形成された、圧電効果を有するものである。センサ素子２０は、保護膜２３ａ、電極２２ａ、圧電フィルム２１、電極２２ｂ、保護膜２３ｂが、この順に積層されたフィルム状の素子である。圧電フィルム２１は、例えば圧電効果を有するプラスチックＰＶＤＦ（Polyvinylidene fluoride）をフィルム状に形成したものである。電極２２ａ、２２ｂが、圧電フィルム２１を挟むように積層されている。電極２２ａ、２２ｂは、例えば銀インクスクリーン印刷により形成したものである。また、保護膜２３ａ、２３ｂが、この順に積層された電極２２ａ、圧電フィルム２１、電極２２ｂを挟むように積層されている。保護膜２３ａ、２３ｂは、薄いアクリルの皮膜であり、電極２２ａ、２２ｂの表面の酸化を抑える。保護膜２３ａ、２３ｂは、電極２２ａ、２２ｂの表面を覆う大きさである。 FIG. 2 is a schematic diagram showing the configuration of the sensor element. The sensor element 20 is formed in a film shape and has a piezoelectric effect. The sensor element 20 is a film-shaped element in which a protective film 23a, an electrode 22a, a piezoelectric film 21, an electrode 22b, and a protective film 23b are laminated in this order. The piezoelectric film 21 is formed by, for example, forming a plastic PVDF (Polyvinylidene fluoride) having a piezoelectric effect into a film shape. The electrodes 22 a and 22 b are stacked so as to sandwich the piezoelectric film 21. The electrodes 22a and 22b are formed, for example, by silver ink screen printing. Further, protective films 23a and 23b are laminated so as to sandwich the electrode 22a, the piezoelectric film 21, and the electrode 22b which are laminated in this order. The protective films 23a and 23b are thin acrylic films and suppress oxidation of the surfaces of the electrodes 22a and 22b. The protective films 23a and 23b are large enough to cover the surfaces of the electrodes 22a and 22b.
　また、電極２２ａ、２２ｂには、出力ライン２４ａ、２４ｂがそれぞれ接続されている。この出力ライン２４ａ、２４ｂは、電極２２ａ、２２ｂに接続されていない他端を端子カバー４０の内側に形成されている出力端子４５に接続している。 (4) Output lines 24a and 24b are connected to the electrodes 22a and 22b, respectively. The other ends of the output lines 24a and 24b that are not connected to the electrodes 22a and 22b are connected to an output terminal 45 formed inside the terminal cover 40.
　センサ素子２０は、圧電フィルム２１にひずみ（変形）が生じると、そのひずみに応じた電圧を出力ライン２４ａ、２４ｂに出力する。このセンサ素子２０は、すでに実用化されているものであるので、ここでは詳細な説明を省略する。 (4) When distortion (deformation) occurs in the piezoelectric film 21, the sensor element 20 outputs a voltage corresponding to the distortion to the output lines 24a and 24b. Since the sensor element 20 has already been put to practical use, a detailed description thereof will be omitted here.
　センサカバー３０は、ベース板１０に積層されているセンサ素子２０を覆うように、貼付されている。このセンサカバー３０は、防水気密用片面粘着テープ（所謂、全天テープ）である。センサカバー３０は、センサ素子２０の変形、変色、劣化等を抑制する。 The sensor cover 30 is attached so as to cover the sensor elements 20 stacked on the base plate 10. The sensor cover 30 is a waterproof and airtight single-sided adhesive tape (so-called all-sky tape). The sensor cover 30 suppresses deformation, discoloration, deterioration, and the like of the sensor element 20.
　また、ひずみセンサ１は、ベース板１０の長手方向におけるセンサ素子２０の一方の端部側に端子カバー４０を設けている。端子カバー４０は、センサ素子２０の出力ライン２４ａ、２４ｂが引き出されている側に設けられている。端子カバー４０は、例えばポリカーボネート製の樹脂を原材料とする成型品である。端子カバー４０は、外形が直方体形状であり、中空の空間を有する箱型形状である。端子カバー４０の幅方向の長さは、ベース板１０の幅方向の長さよりも短い。端子カバー４０は、開口面をベース板１０の積層面に対向する向きに取り付けられ、端子カバー４０の内側の空間内に、出力ライン２４ａ、２４ｂが接続されている出力端子４５が取り付けられている。また、この出力端子４５には、出力ケーブル５０が接続されている。この出力ケーブル５０は、端子カバー４０の側面に形成したケーブルの引き出し孔を通して、外部に引き出されている。端子カバー４０は、接着剤等を使用してベース板１０に取り付けられている。また、ベース板１０に取り付けられている端子カバー４０の内側の空間には、樹脂４１が充填されている。 ひ ず み In addition, the strain sensor 1 has a terminal cover 40 provided on one end side of the sensor element 20 in the longitudinal direction of the base plate 10. The terminal cover 40 is provided on the side from which the output lines 24a and 24b of the sensor element 20 are drawn out. The terminal cover 40 is a molded product using, for example, a polycarbonate resin as a raw material. The terminal cover 40 has a rectangular parallelepiped outer shape and a box shape having a hollow space. The length in the width direction of the terminal cover 40 is shorter than the length in the width direction of the base plate 10. The terminal cover 40 is mounted so that the opening surface faces the laminated surface of the base plate 10, and the output terminal 45 to which the output lines 24 a and 24 b are connected is mounted in the space inside the terminal cover 40. . An output cable 50 is connected to the output terminal 45. The output cable 50 is drawn out through a cable drawing hole formed on the side surface of the terminal cover 40. The terminal cover 40 is attached to the base plate 10 using an adhesive or the like. The resin 41 is filled in a space inside the terminal cover 40 attached to the base plate 10.
　ひずみセンサ１は、図１に示すように、センサ素子２０と、端子カバー４０とをベース板１０の長手方向に並べて取り付けている。また、ひずみセンサ１は、ベース板１０の長手方向の両端部に、センサ素子２０、および端子カバー４０が設けられていない、チャック部１０ａ、１０ｂを有する形状である。チャック部１０ａ、１０ｂでは、ベース板１０が露出している。 As shown in FIG. 1, the strain sensor 1 has a sensor element 20 and a terminal cover 40 arranged side by side in the longitudinal direction of the base plate 10. Further, the strain sensor 1 has a shape in which the sensor elements 20 and the terminal covers 40 are not provided at both ends in the longitudinal direction of the base plate 10 and the chuck portions 10a and 10b are provided. In the chuck portions 10a and 10b, the base plate 10 is exposed.
　＜２．動作例＞
　この例にかかるひずみセンサ１は、図３に示すように、接着剤を用いて、ひずみを検出する検出対象部材に貼り付けて使用する。ひずみセンサ１は、ベース板１０のセンサ素子２０、および端子カバー４０が設けられていない面（ここでは、取付面と言う。）を検出対象部材に貼り付ける。取付面は、積層面に対向する面である。検出対象部材は、構造物である橋梁の鋼材や、構造物であるビルの壁面、ロボットのアーム等である。 <2. Operation example>
As shown in FIG. 3, the strain sensor 1 according to this example is used by being attached to a detection target member for detecting strain using an adhesive. In the strain sensor 1, a surface of the base plate 10 where the sensor element 20 and the terminal cover 40 are not provided (here, referred to as an attachment surface) is attached to a detection target member. The mounting surface is a surface facing the lamination surface. The detection target member is a steel material of a bridge which is a structure, a wall surface of a building which is a structure, an arm of a robot, or the like.
　また、ベース板１０は、ヤング率Ｙを、センサ素子２０のヤング率Ｚよりも大きく、このひずみセンサ１を貼り付ける検出対象部材のヤング率Ｘよりも小さく（Ｚ＜Ｙ＜Ｘ）するのが好ましい。 Further, the base plate 10 preferably has a Young's modulus Y larger than the Young's modulus Z of the sensor element 20 and smaller than the Young's modulus X of the detection target member to which the strain sensor 1 is attached (Z <Y <X). preferable.
　上述したように、ひずみセンサ１は、接着剤等によって、ひずみを検出する検出対象部材に貼り付けられる。具体的には、ひずみセンサ１は、ベース板１０の取付面または検出対象部材の表面に接着剤を塗布し、検出対象部材に貼り付けている。また、ひずみセンサ１は、ベース板１０によってある程度の硬さを有している。また、ひずみセンサ１を取り付けるために、検出対象部材に対して加工を施す必要もない。したがって、ひずみセンサ１は、既存の構造物に対しても、その取り付け作業が簡単に行える。 (4) As described above, the strain sensor 1 is attached to a detection target member for detecting strain with an adhesive or the like. Specifically, in the strain sensor 1, an adhesive is applied to a mounting surface of the base plate 10 or a surface of the detection target member, and is attached to the detection target member. The strain sensor 1 has a certain degree of hardness due to the base plate 10. Further, in order to mount the strain sensor 1, there is no need to process the detection target member. Accordingly, the strain sensor 1 can be easily attached to an existing structure.
　なお、ひずみセンサ１は、両面テープで、ひずみを検出する検出対象部材に貼り付けてもよい。 The strain sensor 1 may be affixed to a detection target member for detecting strain with a double-sided tape.
　また、ひずみセンサ１は、センサカバー３０によってセンサ素子２０を覆っているので、センサ素子２０における外部環境（紫外線や雨等）の影響が抑えられる。すなわち、ひずみセンサ１は、センサカバー３０によってセンサ素子２０に耐候性を持たせているので、ひずみセンサ１（センサ素子２０）の劣化速度が抑えられる。 (4) Since the strain sensor 1 covers the sensor element 20 with the sensor cover 30, the influence of the external environment (ultraviolet rays, rain, etc.) on the sensor element 20 is suppressed. That is, in the strain sensor 1, the sensor element 20 is provided with weather resistance by the sensor cover 30, so that the deterioration rate of the strain sensor 1 (sensor element 20) can be suppressed.
　また、ひずみセンサ１は、貼り付けた検出対象部材と、センサ素子２０との間にベース板１０が位置するので、検出対象部材から染み出てきた雨水等による、センサ素子２０の劣化も抑えられる。 Further, in the strain sensor 1, since the base plate 10 is located between the attached detection target member and the sensor element 20, deterioration of the sensor element 20 due to rainwater or the like leaking from the detection target member can be suppressed. .
　また、ひずみセンサ１は、ベース板１０のヤング率Ｙを、センサ素子２０のヤング率Ｚよりも大きく、このひずみセンサ１を貼り付ける検出対象部材のヤング率Ｘよりも小さく（Ｘ＞Ｙ＞Ｚ）することにより、検出対象部材のひずみを精度よく検出することができる。このことを以下に説明する。 In the strain sensor 1, the Young's modulus Y of the base plate 10 is larger than the Young's modulus Z of the sensor element 20 and smaller than the Young's modulus X of the detection target member to which the strain sensor 1 is attached (X> Y> Z). ), It is possible to accurately detect the distortion of the detection target member. This will be described below.
　ヤング率Ｅとひずみεとの関係は、
　Ｅ＝Ｆ／ε・・・（１）
である。Ｆは、応力である。 The relationship between Young's modulus E and strain ε is
E = F / ε (1)
It is. F is the stress.
　ここで、ベース板１０のヤング率Ｙと、このひずみセンサ１を貼り付けた検出対象部材のヤング率Ｘとの関係が、Ｘ＜Ｙであると、
　Ｆ１＝Ｘε１、Ｆ２＝Ｙε２・・・（２）
である。Ｆ１は、検出対象部材に作用した応力であり、Ｆ２は、ベース板１０に作用した応力である。ε１は、検出対象部材のひずみであり、ε２は、ベース板１０のひずみである。 Here, if the relationship between the Young's modulus Y of the base plate 10 and the Young's modulus X of the detection target member to which the strain sensor 1 is attached is X <Y,
F1 = Xε1, F2 = Yε2 (2)
It is. F1 is the stress applied to the detection target member, and F2 is the stress applied to the base plate 10. ε1 is the strain of the detection target member, and ε2 is the strain of the base plate 10.
　検出対象部材に作用した応力Ｆ１が、ベース板１０に作用したとしても（すなわち、ベース板１０に作用した応力Ｆ２≒検出対象部材に作用した応力Ｆ１であったとしても、）、ベース板１０のヤング率Ｙが検出対象部材のヤング率Ｘよりも大きいので、ベース板１０のひずみε２は、
　ε２＝ε１×（Ｘ／Ｙ）・・・（３）
になる。ここで、Ｘ＜Ｙであることから、０＜（Ｘ／Ｙ）＜１である。したがって、ベース板１０のひずみε２は、検出対象部材のひずみε１よりも小さくなる。 Even if the stress F1 acting on the detection target member acts on the base plate 10 (that is, the stress F2 acting on the base plate 10 ≒ the stress F1 acting on the detection target member), Since the Young's modulus Y is larger than the Young's modulus X of the detection target member, the strain ε2 of the base plate 10 is
ε2 = ε1 × (X / Y) (3)
become. Here, since X <Y, 0 <(X / Y) <1. Therefore, the strain ε2 of the base plate 10 is smaller than the strain ε1 of the detection target member.
　センサ素子２０のひずみε３は、ベース板１０のひずみε２に応じた大きさになるので、検出対象部材のひずみε１に比べて小さくなる。このため、ひずみセンサ１は、ベース板１０のヤング率Ｙと、このひずみセンサ１を貼り付けた検出対象部材のヤング率Ｘとの関係が、Ｘ＜Ｙであると、検出対象部材のひずみε１の検出精度が低下する。 ひ ず み Since the strain ε3 of the sensor element 20 has a magnitude corresponding to the strain ε2 of the base plate 10, it is smaller than the strain ε1 of the detection target member. Therefore, if the relationship between the Young's modulus Y of the base plate 10 and the Young's modulus X of the detection target member to which the strain sensor 1 is attached is X <Y, the strain ε1 of the detection target member Detection accuracy decreases.
　したがって、ひずみセンサ１は、ベース板１０のヤング率Ｙと、このひずみセンサ１を貼り付けた検出対象部材のヤング率Ｘとの関係をＸ＞Ｙにすることにより、検出対象部材のひずみε１≒ベース板１０のひずみε２になるので、検出対象部材のひずみε１の検出精度が向上する。 Therefore, the strain sensor 1 sets the relationship between the Young's modulus Y of the base plate 10 and the Young's modulus X of the detection target member to which the strain sensor 1 is attached to X> Y, whereby the strain ε1 ≒ of the detection target member is obtained. Since the strain ε2 of the base plate 10 is obtained, the detection accuracy of the strain ε1 of the detection target member is improved.
　なお、検出対象部材とベース板１０との間には、ひずみセンサ１を検出対象部材に貼り付けるために使用した、接着剤や、両面テープが存在するので、この接着剤や、両面テープによって応力の吸収が生じる。したがって、検出対象部材に作用した応力Ｆ１と、ベース板１０に作用した応力Ｆ２とは等しくない。 Note that an adhesive or a double-sided tape used for attaching the strain sensor 1 to the detection target member exists between the detection target member and the base plate 10. Absorption occurs. Therefore, the stress F1 applied to the detection target member and the stress F2 applied to the base plate 10 are not equal.
　さらに、ひずみセンサ１は、ベース板１０のヤング率Ｙを、センサ素子２０のヤング率Ｚよりも大きくすることにより、上述した検出対象部材とベース板１０との関係と同様に、ベース板１０のひずみε２≒センサ素子２０のひずみε３、になる。すなわち、検出対象部材のひずみε１≒センサ素子２０のひずみε３になる。 Further, the strain sensor 1 makes the Young's modulus Y of the base plate 10 larger than the Young's modulus Z of the sensor element 20, and thereby the base plate 10 has the same structure as the above-described relationship between the detection target member and the base plate 10. The strain ε2 ≒ the strain ε3 of the sensor element 20. That is, the strain ε1 of the detection target member 部 材 the strain ε3 of the sensor element 20.
　したがって、各ヤング率の関係をＸ＞Ｙ＞Ｚとすると、検出対象部材のひずみε１の検出精度を向上できる。 Accordingly, if the relationship among the Young's moduli is X> Y> Z, the detection accuracy of the strain ε1 of the detection target member can be improved.
　なお、上述した検出対象部材のヤング率Ｘ、ベース板１０のヤング率Ｙ、およびセンサ素子２０のヤング率Ｚの関係（Ｚ＜Ｙ＜Ｘ）は、検出対象部材のひずみε１の検出精度を向上させる上で好ましい関係であり、この関係が成立しないものが本願発明に含まれないという意味ではない。 The relationship between the Young's modulus X of the detection target member, the Young's modulus Y of the base plate 10, and the Young's modulus Z of the sensor element 20 (Z <Y <X) improves the detection accuracy of the strain ε1 of the detection target member. It is a preferable relationship in making the relationship, and it does not mean that a material that does not satisfy this relationship is not included in the present invention.
　また、ひずみセンサ１は、ベース板１０を絶縁材料で形成しているので、センサ素子２０で発生した電荷の漏れ、およびセンサ素子２０への外部からの電荷の流入を抑えられる。 In addition, since the base plate 10 of the strain sensor 1 is formed of an insulating material, leakage of electric charges generated in the sensor element 20 and inflow of electric charges from the outside into the sensor element 20 can be suppressed.
　次に、この例にかかるひずみセンサ１について、圧電フィルム２１の厚さ方向に直交する方向（ここでは、延伸方向と言う。）における圧電定数ｄ31の測定について説明する。この例では、圧電定数ｄ31を、ひずみセンサ１の出力感度特性として測定する。図１に示したように、この例にかかるひずみセンサ１は、長手方向の両端部に、センサ素子２０、および端子カバー４０が設けられておらず、ベース板１０が露出しているチャック部１０ａ、１０ｂを有する。 Next, the strain sensor 1 according to this example (here, referred to the stretching direction.) Direction perpendicular to the thickness direction of the piezoelectric film 21 for measurement of the piezoelectric constant d 31 in the describing. In this example, the piezoelectric constant d 31, measured as the output sensitivity of the strain sensor 1. As shown in FIG. 1, the strain sensor 1 according to this example does not include the sensor element 20 and the terminal cover 40 at both ends in the longitudinal direction, and the chuck portion 10 a in which the base plate 10 is exposed. , 10b.
　図４は、ひずみセンサの圧電定数ｄ31を測定する測定器の概略図である。図４では、測定器１００にセットしたひずみセンサ１を破線で示している。この測定器１００は、上端保持部１０１と、下端保持部１０２と、スライド部材１０３とを有している。上端保持部１０１は、ひずみセンサ１の長手方向の一方の端部に位置するチャック部１０ａを挟持して保持する構造である。下端保持部１０２は、ひずみセンサ１の長手方向の他方の端部に位置するチャック部１０ｂを挟持して保持する構造である。上端保持部１０１がひずみセンサ１の長手方向の一方の端部を保持する保持部と、下端保持部１０２がひずみセンサ１の長手方向の他方の端部を保持する保持部と、は対向している。 Figure 4 is a schematic view of a measuring device for measuring the piezoelectric constant d 31 of the strain sensor. In FIG. 4, the strain sensor 1 set on the measuring instrument 100 is indicated by a broken line. The measuring device 100 has an upper end holding portion 101, a lower end holding portion 102, and a slide member 103. The upper end holding portion 101 has a structure for holding and holding the chuck portion 10 a located at one end in the longitudinal direction of the strain sensor 1. The lower end holding portion 102 has a structure for holding and holding the chuck portion 10b located at the other end of the strain sensor 1 in the longitudinal direction. The holding part where the upper end holding part 101 holds one end in the longitudinal direction of the strain sensor 1 and the holding part where the lower end holding part 102 holds the other end in the longitudinal direction of the strain sensor 1 face each other. I have.
　スライド部材１０３は、図示していないスライド機構部によって、下端保持部１０２に対して接離する方向（図４における上下方向）にスライド自在に取り付けられている。また、上端保持部１０１は、スライド部材１０３に取り付けられている。すなわち、上端保持部１０１は、スライド部材１０３のスライドにともなって、下端保持部１０２に対して接離する方向にスライドする。 The slide member 103 is slidably attached to the lower end holding portion 102 (in the vertical direction in FIG. 4) by a slide mechanism (not shown). Further, the upper end holding part 101 is attached to the slide member 103. In other words, the upper end holding portion 101 slides in the direction in which the upper end holding portion 101 comes into contact with and separates from the lower end holding portion 102 as the slide member 103 slides.
　なお、ここでは、上端保持部１０１がチャック部１０ａを保持し、下端保持部１０２がチャック部１０ｂを保持するとしているが、上端保持部１０１がチャック部１０ｂを保持し、下端保持部１０２がチャック部１０ａを保持してもよい。 Here, it is assumed that the upper end holding portion 101 holds the chuck portion 10a and the lower end holding portion 102 holds the chuck portion 10b, but the upper end holding portion 101 holds the chuck portion 10b and the lower end holding portion 102 holds the chuck portion 10b. The part 10a may be held.
　図４に示すように、ひずみセンサ１を測定器１００にセットし、ひずみセンサ１の長手方向に作用させる引張力の大きさを変化させながら、このひずみセンサ１の出力を計測することにより、圧電定数ｄ31を測定する。測定器１００は、スライド部材１０３を下端保持部１０２から離れる方向にスライドすることにより、ひずみセンサ１の長手方向に作用させる引張力を大きくできる。したがって、ひずみセンサ１毎に、そのひずみセンサ１の圧電定数ｄ31の測定が比較的簡単に行える。これにより、検出対象部材のひずみ量の算出において、使用しているひずみセンサ１について測定した圧電定数ｄ31によって、当該ひずみセンサ１の出力感度特性を定めることができる。したがって、検出対象部材のひずみ量の計測精度を向上させることができる。 As shown in FIG. 4, by setting the strain sensor 1 on the measuring device 100 and measuring the output of the strain sensor 1 while changing the magnitude of the tensile force applied in the longitudinal direction of the strain sensor 1, the constant d 31 is measured. The measuring device 100 can increase the tensile force applied in the longitudinal direction of the strain sensor 1 by sliding the slide member 103 in a direction away from the lower end holding portion 102. Thus, each strain sensor 1, enabling the measurement is relatively simple in piezoelectric constant d 31 of the strain sensor 1. Thus, in the calculation of the amount of strain detected member, the piezoelectric constant d 31 measured for the strain sensor 1 is used, it is possible to determine the output sensitivity characteristic of the strain sensor 1. Therefore, it is possible to improve the measurement accuracy of the strain amount of the detection target member.
　また、ひずみセンサ１は、圧電定数ｄ31の測定時に、測定器１００によってセンサ素子２０、および端子カバー４０が保持されないので、破損することもない。 Also, the strain sensor 1, when the measurement of the piezoelectric constant d 31, the sensor element 20 by the measuring device 100, and since the terminal cover 40 is not held, nor damaged.
　また、上記の説明では、測定器１００は、ひずみセンサ１を鉛直方向に引っ張る構成であるが、ひずみセンサ１を引っ張る方向は、ひずみセンサ１の長手方向であればよい。例えば、測定器１００は、セットされたひずみセンサ１を水平方向に引っ張る構成であってもよい。 In the above description, the measuring device 100 is configured to pull the strain sensor 1 in the vertical direction. However, the direction in which the strain sensor 1 is pulled may be the longitudinal direction of the strain sensor 1. For example, the measuring device 100 may be configured to pull the set strain sensor 1 in the horizontal direction.
　＜３．変形例＞
　以下において説明するひずみセンサの各変形例では、上記したひずみセンサ１と同様の構成については、同じ符号を付している。また、同様の構成については、その説明を省略する場合がある。 <3. Modification>
In each of the modified examples of the strain sensor described below, the same components as those of the above-described strain sensor 1 are denoted by the same reference numerals. In addition, the description of the same configuration may be omitted.
　図５は、別の例（第１の変形例）にかかるひずみセンサを示す平面図（図１（Ａ）に相当する図）である。この例にかかるひずみセンサ１Ａは、チャック部１０ａ、１０ｂに中心線１１ａ、１１ｂをマーキングした点で、上記の例と異なっている。中心線１１ａ、１１ｂは、ひずみセンサ１Ａの長手方向に延びる線であり、ひずみセンサ１Ａの幅方向の略中心にマーキングしている。 FIG. 5 is a plan view (a diagram corresponding to FIG. 1A) showing a strain sensor according to another example (first modification). The strain sensor 1A according to this example is different from the above example in that the center lines 11a and 11b are marked on the chuck portions 10a and 10b. The center lines 11a and 11b are lines extending in the longitudinal direction of the strain sensor 1A, and are marked at substantially the center in the width direction of the strain sensor 1A.
　ひずみセンサ１Ａを図４に示した測定器１００にセットするときに、この中心線１１ａ、１１ｂを基準線として利用することによって、ひずみセンサ１Ａがまっすぐ立設するようにセットできる。 (4) When the strain sensor 1A is set on the measuring instrument 100 shown in FIG. 4, by using the center lines 11a and 11b as reference lines, the strain sensor 1A can be set upright.
　図６は、また別の例（第２の変形例）にかかるひずみセンサを示す平面図（図１（Ａ）に相当する図）である。この例にかかるひずみセンサ１Ｂは、長手方向の両端部に位置するチャック部１０ａ、１０ｂの幅を他の部分（センサ素子２０、および端子カバー４０が取り付けられている部分）よりも細くした形状である。 FIG. 6 is a plan view (a diagram corresponding to FIG. 1A) showing a strain sensor according to another example (a second modification). The strain sensor 1B according to this example has a shape in which the widths of the chuck portions 10a and 10b located at both ends in the longitudinal direction are narrower than other portions (the portions where the sensor element 20 and the terminal cover 40 are attached). is there.
　なお、チャック部１０ａと、チャック部１０ｂとは、同じ幅である。 The chuck 10a and the chuck 10b have the same width.
　図７は、また別の例（第３の変形例）にかかるひずみセンサを示す平面図（図１（Ａ）に相当する図）である。この例にかかるひずみセンサ１Ｃは、長手方向の両端部に位置するチャック部１０ａ、１０ｂの幅を他の部分（センサ素子２０、および端子カバー４０が取り付けられている部分）よりも太くした形状である。 FIG. 7 is a plan view (a diagram corresponding to FIG. 1A) showing a strain sensor according to another example (third modification). The strain sensor 1C according to this example has a shape in which the widths of the chuck portions 10a and 10b located at both ends in the longitudinal direction are wider than other portions (the portions where the sensor element 20 and the terminal cover 40 are attached). is there.
　なお、チャック部１０ａと、チャック部１０ｂとは、同じ幅である。 The chuck 10a and the chuck 10b have the same width.
　図８は、また別の例（第４の変形例）にかかるひずみセンサの概略図である。図８（Ａ）は、平面図であり、図８（Ｂ）は、図８（Ａ）に示すＡ－Ａ線部の断面図である。この例にかかるひずみセンサ１Ｄは、上記した例の出力端子４５を、出力回路４６に置き換えた構成である。 FIG. 8 is a schematic view of a strain sensor according to another example (fourth modification). 8A is a plan view, and FIG. 8B is a cross-sectional view taken along the line AA shown in FIG. The strain sensor 1D according to this example has a configuration in which the output terminal 45 of the above-described example is replaced with an output circuit 46.
　センサ素子２０の出力ライン２４ａ、２４ｂは、電極２２ａ、２２ｂに接続されていない他端を端子カバー４０の内側に取り付けた出力回路４６の入力端子に接続している。出力ケーブル５０は、出力回路４６の出力端子に接続している。 The output lines 24a and 24b of the sensor element 20 are connected to the input terminals of the output circuit 46 attached to the inside of the terminal cover 40 at the other end not connected to the electrodes 22a and 22b. The output cable 50 is connected to an output terminal of the output circuit 46.
　図９は、出力回路を示す回路図である。この図９に示す出力回路４６は、センサ素子２０において、当該センサ素子２０のひずみ量に応じて発生した電荷に応じた電圧を計測信号として出力するチャージアンプ回路である。出力回路４６の出力がひずみセンサ１の計測信号である。出力回路４６は、アンプＡｍｐのマイナス入力端子と出力端子との間に、センサ素子２０で発生した電荷をチャージするコンデンサＣｆを接続している。また、出力回路４６は、リーク電流を逃がすための抵抗ＲをコンデンサＣｆに並列に接続している。この出力回路４６は、コンデンサＣｆにチャージされた電荷Ｑに応じた電圧Ｖを出力する。図９に示す、ｏｕｔ（＋）、およびｏｕｔ（－）は、出力回路４６の出力端子であり、出力ケーブル５０は、一端が出力回路４６の出力端子に接続されている。 FIG. 9 is a circuit diagram showing an output circuit. The output circuit 46 shown in FIG. 9 is a charge amplifier circuit that outputs, as a measurement signal, a voltage corresponding to the charge generated in the sensor element 20 according to the amount of distortion of the sensor element 20. The output of the output circuit 46 is a measurement signal of the strain sensor 1. The output circuit 46 has a capacitor Cf connected between the negative input terminal and the output terminal of the amplifier Amp for charging the electric charge generated in the sensor element 20. Further, the output circuit 46 connects a resistor R for releasing a leak current in parallel with the capacitor Cf. The output circuit 46 outputs a voltage V according to the charge Q charged in the capacitor Cf. Out (+) and out (−) shown in FIG. 9 are output terminals of the output circuit 46, and one end of the output cable 50 is connected to the output terminal of the output circuit 46.
　この出力回路４６の出力電圧Ｖは、
　出力電圧Ｖ＝Ｑ×コンデンサＣｆの容量
である。コンデンサＣｆには、センサ素子２０で発生した電荷（当該センサ素子２０のひずみ量に応じて発生した電荷）がチャージされる。すなわち。出力回路４６は、センサ素子２０のひずみ量に応じた電圧を出力する。 The output voltage V of this output circuit 46 is
Output voltage V = Q × capacitance of capacitor Cf. The capacitor Cf is charged with electric charge generated by the sensor element 20 (electric charge generated according to the amount of distortion of the sensor element 20). That is. The output circuit 46 outputs a voltage according to the amount of distortion of the sensor element 20.
　なお、上述したように、出力回路４６は、ベース板１０に取り付けられ、端子カバー４０に覆われている。 As described above, the output circuit 46 is attached to the base plate 10 and covered by the terminal cover 40.
　この例にかかるひずみセンサ１Ｄも、上記の例と同様に、接着剤等を用いて、ひずみを検出する検出対象部材に貼り付けて使用する。 ひ ず み Similarly to the above example, the strain sensor 1D according to this example is also used by attaching it to a detection target member for detecting strain using an adhesive or the like.
　また、ひずみセンサ１Ｄは、端子カバー４０によって出力回路４６を覆い、この端子カバー４０の内側の空間に樹脂４１を充填しているので、出力回路４６に対する外部環境（紫外線や雨等）の影響が抑えられる。すなわち、ひずみセンサ１Ｄは、端子カバー４０、および樹脂４１によって出力回路４６に耐候性を持たせているので、出力回路４６の劣化速度が抑えられる。 In the strain sensor 1D, the output circuit 46 is covered by the terminal cover 40, and the space inside the terminal cover 40 is filled with the resin 41, so that the output circuit 46 is not affected by the external environment (ultraviolet rays, rain, etc.). Can be suppressed. That is, in the strain sensor 1D, the output circuit 46 is provided with weather resistance by the terminal cover 40 and the resin 41, so that the deterioration speed of the output circuit 46 can be suppressed.
　また、ひずみセンサ１Ｄは、ベース板１０により、検出対象部材から染み出てきた雨水等による、センサ素子２０、および出力回路４６の劣化も抑えられる。 In addition, in the strain sensor 1D, the deterioration of the sensor element 20 and the output circuit 46 due to rainwater or the like leaking from the detection target member is suppressed by the base plate 10.
　なお、このひずみセンサ１Ｄも、ベース板１０のヤング率Ｙ、センサ素子２０のヤング率Ｚおよび検出対象部材のヤング率Ｘを、上記の例と同様に、Ｘ＞Ｙ＞Ｚにすることにより、検出対象部材のひずみを精度よく検出することができる。 The strain sensor 1D also has a Young's modulus Y of the base plate 10, a Young's modulus Z of the sensor element 20, and a Young's modulus X of the detection target member, where X> Y> Z, as in the above example. The distortion of the detection target member can be accurately detected.
　次に、この例にかかるひずみセンサ１Ｄの出力感度特性の測定について説明する。この例で言う出力感度特性とは、圧電フィルム２１のひずみ量と、出力回路４６の出力である計測信号との関係である。この例にかかるひずみセンサ１Ｄも、長手方向の両端部に、センサ素子２０、および端子カバー４０が設けられておらず、ベース板１０が露出しているチャック部１０ａ、１０ｂを有する。 Next, the measurement of the output sensitivity characteristic of the strain sensor 1D according to this example will be described. The output sensitivity characteristic referred to in this example is a relationship between a distortion amount of the piezoelectric film 21 and a measurement signal output from the output circuit 46. The strain sensor 1D according to this example also has chuck portions 10a and 10b in which the sensor element 20 and the terminal cover 40 are not provided at both ends in the longitudinal direction and the base plate 10 is exposed.
　この例にかかるひずみセンサ１Ｄについても、出力感度特性の測定は、図４に示した測定器１００で行われる。このひずみセンサ１Ｄについて測定される出力感度特性は、圧電フィルム２１の特性、出力回路４６を構成する回路部品等の電気的特性、およびセンサ素子２０と出力回路４６との電気的接続等にかかる接続特性等の影響を受けている。したがって、このひずみセンサ１Ｄによる検出対象部材のひずみ量の計測（センシング）が、使用するひずみセンサ１Ｄについて実測した出力感度特性を用いて行える。すなわち、ひずみセンサ１の個体差（圧電フィルム２１の特性、出力回路４６を構成する回路部品等の電気的特性、およびセンサ素子２０と出力回路４６との電気的接続等にかかる接続特性等）による影響を受けることなく、橋梁やビル等の様々な種類の構造物に生じたひずみ量を精度よく計測できる。これにより、ひずみセンサ１Ｄを使用した構造物の状態の診断がより適正に行える。 に つ い て Also for the strain sensor 1D according to this example, the measurement of the output sensitivity characteristic is performed by the measuring device 100 shown in FIG. The output sensitivity characteristics measured for the strain sensor 1D include the characteristics of the piezoelectric film 21, the electrical characteristics of the circuit components and the like constituting the output circuit 46, and the connection relating to the electrical connection between the sensor element 20 and the output circuit 46, and the like. It is affected by characteristics. Therefore, measurement (sensing) of the strain amount of the detection target member by the strain sensor 1D can be performed using the output sensitivity characteristics actually measured for the strain sensor 1D to be used. That is, it is caused by individual differences of the strain sensor 1 (characteristics of the piezoelectric film 21, electric characteristics of circuit components and the like constituting the output circuit 46, connection characteristics related to electric connection between the sensor element 20 and the output circuit 46, and the like). Without being affected, it is possible to accurately measure the amount of strain generated in various types of structures such as bridges and buildings. Thereby, the diagnosis of the state of the structure using the strain sensor 1D can be performed more appropriately.
　また、ひずみセンサ１Ｄも、出力感度特性の測定時に、測定器１００によってセンサ素子２０、および端子カバー４０（出力回路４６を含む。）が保持されないので、破損することもない。 Also, since the sensor element 20 and the terminal cover 40 (including the output circuit 46) are not held by the measuring instrument 100 when the output sensitivity characteristic is measured, the strain sensor 1D is not damaged.
　また、上記の例では、出力回路４６は、ベース板１０に取り付けられている構成であるとしたが、図１０に示すような構成にしてもよい。図１０に示すひずみセンサ１Ｅは、上述した出力回路４６を端子カバー４０の内部に取り付けていない。この例にかかるひずみセンサ１Ｅは、出力回路４６をベース板１０とは別に形成した収納ケース４７の内部に取り付けた構成である。収納ケース４７は、例えばポリカーボネート製の樹脂を原材料とする成型品である。収納ケース４７の内部には、出力回路４６を収納する空間が形成されている。 In the above example, the output circuit 46 is configured to be mounted on the base plate 10, but may be configured as shown in FIG. In the strain sensor 1E shown in FIG. 10, the output circuit 46 described above is not mounted inside the terminal cover 40. The strain sensor 1E according to this example has a configuration in which the output circuit 46 is mounted inside a storage case 47 formed separately from the base plate 10. The storage case 47 is a molded product made of, for example, a polycarbonate resin as a raw material. Inside the storage case 47, a space for storing the output circuit 46 is formed.
　ベース板１０に取り付けられているセンサ素子２０と、収納ケース４７の内部に取り付けた出力回路４６とは、接続ケーブル５１によって電気的に接続されている。具体的には、接続ケーブル５１は、センサ素子２０の出力ライン２４ａ、２４ｂと、出力回路４６の入力端子とを電気的に接続する。出力ケーブル５２は、上記の例と同様に、出力回路４６の出力端子に電気的に接続されている。 The sensor element 20 mounted on the base plate 10 and the output circuit 46 mounted inside the storage case 47 are electrically connected by a connection cable 51. Specifically, the connection cable 51 electrically connects the output lines 24a and 24b of the sensor element 20 and the input terminals of the output circuit 46. The output cable 52 is electrically connected to the output terminal of the output circuit 46 as in the above example.
　また、上記した例で説明した出力端子４５が、ベース板１０に取り付けられていてもよい。出力端子４５は、端子カバー４０の内側に位置するように、ベース板１０に取り付けられる。 The output terminal 45 described in the above example may be attached to the base plate 10. The output terminal 45 is attached to the base plate 10 so as to be located inside the terminal cover 40.
　なお、出力回路４６を内部に収納している収納ケース４７は、樹脂が内部に充填されていてもよいし、充填されていなくてもよい。 The storage case 47 housing the output circuit 46 may or may not be filled with resin.
　また、図１０に示すひずみセンサ１Ｅは、上述した出力感度特性の測定において、出力ケーブル５２の電圧の計測に加えて、接続ケーブル５１の電圧をも計測することで、圧電フィルム２１の延伸方向の圧電定数ｄ31についても測定できる。 Further, the strain sensor 1E shown in FIG. 10 measures the voltage of the connection cable 51 in addition to the measurement of the voltage of the output cable 52 in the measurement of the output sensitivity characteristics described above, so that the piezoelectric film 21 in the stretching direction is measured. It can be measured for piezoelectric constant d 31.
　また、図１０に示す例では、ベース板１０の形状を図１に示した形状にしているが、図５、図６、または図７等に示した形状にしてもよい。 In the example shown in FIG. 10, the base plate 10 has the shape shown in FIG. 1, but may have the shape shown in FIG. 5, FIG. 6, or FIG.
　また、出力回路４６は、図９に示した回路に限らず、他の回路で構成してもよい。図１１～図１６は、それぞれ別の例にかかる出力回路を示す図である。図１１～図１６に示す出力回路４６ａ～４６ｆについて、簡単に説明する。 The output circuit 46 is not limited to the circuit shown in FIG. 9 and may be constituted by another circuit. 11 to 16 are diagrams each showing an output circuit according to another example. The output circuits 46a to 46f shown in FIGS. 11 to 16 will be briefly described.
　図１１に示す出力回路４６ａは、抵抗Ｒ１の両端に、センサ素子２０（圧電フィルム２１）に生じたひずみに応じた電圧が印加される。この出力回路４６ａは、公知のボルテージフォロアであり、抵抗Ｒ１の両端に印加されている電圧を出力する。 出力 In the output circuit 46a shown in FIG. 11, a voltage corresponding to the strain generated in the sensor element 20 (piezoelectric film 21) is applied to both ends of the resistor R1. The output circuit 46a is a known voltage follower, and outputs a voltage applied across the resistor R1.
　また、図１２に示す出力回路４６ｂは、抵抗Ｒ２の両端に、センサ素子２０（圧電フィルム２１）に生じたひずみに応じた電圧が印加される。この出力回路４６ｂは、抵抗Ｒ１の両端に印加されている電圧を、（（Ｒａ＋Ｒｂ）／Ｒａ）倍に増幅して出力する増幅回路である。 {Circle around (2)} In the output circuit 46b shown in FIG. 12, a voltage corresponding to the strain generated in the sensor element 20 (piezoelectric film 21) is applied across the resistor R2. The output circuit 46b is an amplifier circuit that amplifies the voltage applied to both ends of the resistor R1 by ((Ra + Rb) / Ra) times and outputs the amplified voltage.
　また、図１３、および図１４に示す出力回路４６ｃ、４６ｄは、ＦＥＴを使用した回路である。図１３に示す出力回路４６ｃは、ドレイン接地回路であり、抵抗Ｒ３の両端に印加されている電圧を出力する。抵抗Ｒ３の両端には、センサ素子２０（圧電フィルム２１）に生じたひずみに応じた電圧が印加される。また、図１４に示す出力回路４６ｄは、ソース接地回路であり、抵抗Ｒ４の両端に印加されている電圧を（Ｒｄ／Ｒｅ）倍に増幅して出力する。抵抗Ｒ４の両端には、センサ素子２０（圧電フィルム２１）に生じたひずみに応じた電圧が印加される。 The output circuits 46c and 46d shown in FIGS. 13 and 14 are circuits using FETs. The output circuit 46c shown in FIG. 13 is a common drain circuit, and outputs a voltage applied to both ends of the resistor R3. A voltage corresponding to the strain generated in the sensor element 20 (piezoelectric film 21) is applied to both ends of the resistor R3. The output circuit 46d shown in FIG. 14 is a common source circuit, and amplifies the voltage applied across the resistor R4 by (Rd / Re) times and outputs the amplified voltage. A voltage corresponding to the strain generated in the sensor element 20 (piezoelectric film 21) is applied to both ends of the resistor R4.
　また、図１５に示す出力回路４６ｅは、センサ素子２０（圧電フィルム２１）で生じたひずみに応じた電圧が、設定電圧を超えたときに、ハイレベルを出力するトリガ回路である。この設定電圧は、可変抵抗ＶＲの抵抗値を変化させることにより、設定できる。 The output circuit 46e shown in FIG. 15 is a trigger circuit that outputs a high level when a voltage corresponding to a strain generated in the sensor element 20 (piezoelectric film 21) exceeds a set voltage. This set voltage can be set by changing the resistance value of the variable resistor VR.
　また、図１６に示す出力回路４６ｆは、センサ素子２０（圧電フィルム２１）で生じた電圧が、抵抗Ｒｆに印加されている電圧Ｖ以上である場合に、センサ素子２０（圧電フィルム２１）で生じた電圧を出力する回路である。 In addition, the output circuit 46f shown in FIG. 16 generates the voltage at the sensor element 20 (piezoelectric film 21) when the voltage generated at the sensor element 20 (piezoelectric film 21) is equal to or higher than the voltage V applied to the resistor Rf. This is a circuit that outputs a voltage.
　なお、上記した出力回路４６、４６ａ～４６ｆを動作させるのに必要な電源電圧は、この出力回路に設けた電池等によって供給する構成であってもよいし、外部機器（例えば、口述するセンサノード１１０）から供給する構成であってもよい。出力回路４６、４６ａ～４６ｆに対する外部機器からの電源電圧の供給は、出力ケーブル５０、５２を利用して行えばよい。 The power supply voltage required to operate the above-described output circuits 46, 46a to 46f may be supplied by a battery or the like provided in this output circuit, or may be an external device (for example, a sensor node 110). The supply of the power supply voltage from the external device to the output circuits 46 and 46a to 46f may be performed using the output cables 50 and 52.
　次に、上記した例のいずれかのひずみセンサ１を備えるセンサノードについて説明する。図１７は、センサノードの主要部の構成を示す図である。センサノード１１０は、状態を診断する構造物について、その診断に用いる各種の物理量を計測し、診断装置（不図示）に出力する。図１７に示すように、センサノード１１０は、制御部１１１と、センサ制御回路１１２～１１５と、タイマ１１６と、記憶部１１７と、無線通信部１１８と、電源部１１９とを備えている。 Next, a sensor node including any one of the strain sensors 1 in the above-described example will be described. FIG. 17 is a diagram illustrating a configuration of a main part of the sensor node. The sensor node 110 measures various physical quantities used for the diagnosis of the structure whose state is to be diagnosed, and outputs the measured physical quantities to a diagnostic device (not shown). As shown in FIG. 17, the sensor node 110 includes a control unit 111, sensor control circuits 112 to 115, a timer 116, a storage unit 117, a wireless communication unit 118, and a power supply unit 119.
　制御部１１１は、センサノード１１０本体各部の動作を制御する。 The control unit 111 controls the operation of each unit of the sensor node 110 main body.
　センサ制御回路１１２には、上述したいずれかの例にかかるひずみセンサ１が接続される。また、センサ制御回路１１３～１１５には、センサ１２１～１２３が接続される。センサ制御回路１１２～１１５は、接続されているひずみセンサ１、およびセンサ１２１～１２３の検知信号（センシング信号）を処理し、センシングデータ（計測された物理量）を取得する処理回路を備える。ひずみセンサ１の検知信号は、上述した出力回路４６（または４６ａ～４６ｆ）の出力信号である。センサ制御回路１１２～１１５は、接続されるひずみセンサ１、およびセンサ１２１～１２３に応じた処理回路を備える。すなわち、各センサ制御回路１１２～１１５は、処理回路の回路構成が同じであるとは限らない。 The strain sensor 1 according to any of the above-described examples is connected to the sensor control circuit 112. Further, sensors 121 to 123 are connected to the sensor control circuits 113 to 115, respectively. The sensor control circuits 112 to 115 include processing circuits that process detection signals (sensing signals) of the connected strain sensors 1 and sensors 121 to 123 and obtain sensing data (measured physical quantities). The detection signal of the strain sensor 1 is an output signal of the output circuit 46 (or 46a to 46f) described above. The sensor control circuits 112 to 115 include a processing circuit corresponding to the strain sensor 1 to be connected and the sensors 121 to 123. That is, the sensor control circuits 112 to 115 do not always have the same circuit configuration of the processing circuit.
　なお、センサ１２１～１２３は、上述したひずみセンサ１であってもよいし、構造物の加速度、構造物の変位量、構造物の振動周波数、構造物周辺の温度、構造物周辺の湿度、構造物の赤外線量、構造物周辺の風速等をセンシングする他の種類のセンサであってもよい。また、この例では、センサノード１１０は、ひずみセンサ１、およびセンサ１２１～１２３が接続される構成（４つのセンサが接続される構成）であるとしたが、接続されるセンサの数（すなわち、センサ制御回路の数）は５つ以上であってもよいし、３つ以下であってもよい。また、センサノード１１０は、一部のセンサ制御回路１１２～１１５に、ひずみセンサ１、およびセンサ１２１～１２３を接続していない状態で使用してもよい。 The sensors 121 to 123 may be the strain sensors 1 described above, or may include the acceleration of the structure, the displacement of the structure, the vibration frequency of the structure, the temperature around the structure, the humidity around the structure, and the structure. Other types of sensors that sense the amount of infrared rays of an object, the wind speed around a structure, and the like may be used. In this example, the sensor node 110 has a configuration in which the strain sensor 1 and the sensors 121 to 123 are connected (a configuration in which four sensors are connected), but the number of connected sensors (ie, The number of sensor control circuits) may be five or more, or three or less. Further, the sensor node 110 may be used in a state where the strain sensor 1 and the sensors 121 to 123 are not connected to some of the sensor control circuits 112 to 115.
　タイマ１１６は、現在の日時を計時する。 The timer 116 counts the current date and time.
　記憶部１１７は、センサノード１１０の動作時に用いる各種設定パラメータや、接続されているひずみセンサ１、およびセンサ１２１～１２３から入力された計測信号を処理して取得した物理量（構造物のひずみ量、構造物の加速度、構造物の変位量、構造物の振動周波数、構造物周辺の温度、構造物周辺の湿度、構造物の赤外線量、構造物周辺の風速等）を一時的に記憶する。 The storage unit 117 stores various setting parameters used during the operation of the sensor node 110 and physical quantities (strain amounts of structures, distortion amounts of structures, and the like) obtained by processing measurement signals input from the connected strain sensors 1 and sensors 121 to 123. The acceleration of the structure, the amount of displacement of the structure, the vibration frequency of the structure, the temperature around the structure, the humidity around the structure, the amount of infrared radiation of the structure, the wind speed around the structure, etc. are temporarily stored.
　無線通信部１１８は、計測した構造物の各種物理量の送信先である装置との間における無線通信を制御する。各種物理量の送信先である装置とは、複数のセンサノード１１０から収集した各種物理量を用いて、構造物の状態を診断する診断装置（不図示）であってもよいし、センサノード１１０と、診断装置との間で送受信される各種物理量を中継する中継装置（不図示）であってもよい。 The wireless communication unit 118 controls wireless communication with a device to which various physical quantities of the measured structure are transmitted. The device that is the transmission destination of various physical quantities may be a diagnostic device (not shown) that diagnoses the state of the structure using various physical quantities collected from the plurality of sensor nodes 110. A relay device (not shown) for relaying various physical quantities transmitted / received to / from the diagnostic device may be used.
　電源部１１９は、バッテリ１１９ａを備えている。バッテリ１１９ａは、センサノード１１０の駆動電源である。電源部１１９は、センサノード１１０本体各部に対して動作に必要な電力をバッテリ１１９ａから供給する。また、この例では、センサノード１１０は、センサ制御回路１１２～１１５に対する電源供給を必要に応じて行う。具体的には、電源部１１９は、センサ制御回路１１２～１１５に対するバッテリ１１９ａからの駆動電源の供給を、制御部１１１からの指示にしたがってオン／オフする。 (4) The power supply unit 119 includes a battery 119a. The battery 119a is a drive power supply for the sensor node 110. The power supply unit 119 supplies power required for operation to each unit of the sensor node 110 main body from the battery 119a. In this example, the sensor node 110 supplies power to the sensor control circuits 112 to 115 as needed. Specifically, the power supply unit 119 turns on / off the supply of drive power from the battery 119a to the sensor control circuits 112 to 115 in accordance with an instruction from the control unit 111.
　なお、電源部１１９がセンサ制御回路１１２～１１５に対して駆動電源の供給をオフしている状態（駆動電源の供給停止状態）とは、センサ制御回路１１２～１１５に対して電力の供給が全く行われていない状態であってもよいが、この状態のみに限るものではない。ここで言う駆動電源の供給停止状態とは、電源部１１９がセンサ制御回路１１２～１１５、および接続されているセンサ１２１～１２３が適正に動作するのに必要な電力の供給を行っていない状態である。例えば、電源部１１９が、センサ制御回路１１２～１１５、および接続されているセンサ１２１～１２３の起動に要する時間を短縮するため、センサ制御回路１１２～１１５、および接続されているセンサ１２１～１２３が待機状態（スリープ状態）を保つのに必要な電力を供給している状態も、ここで言う駆動電源の供給停止状態に含まれる。 Note that the state in which the power supply unit 119 turns off the supply of the drive power to the sensor control circuits 112 to 115 (the state in which the supply of the drive power is stopped) means that the supply of power to the sensor control circuits 112 to 115 is not performed at all. The state may not be performed, but is not limited to this state. The drive power supply stop state referred to here is a state in which the power supply unit 119 is not supplying power necessary for the sensor control circuits 112 to 115 and the connected sensors 121 to 123 to operate properly. is there. For example, in order to reduce the time required for the power supply unit 119 to activate the sensor control circuits 112 to 115 and the connected sensors 121 to 123, the sensor control circuits 112 to 115 and the connected sensors 121 to 123 are used. The state in which the power required to maintain the standby state (sleep state) is supplied is also included in the drive power supply stop state referred to herein.
　また、この例では、センサノード１１０は、バッテリ１１９ａが駆動電源である構成としているが、商用電源が駆動電源である構成であってもよい。 Also, in this example, the sensor node 110 has a configuration in which the battery 119a is a driving power source, but may have a configuration in which a commercial power source is a driving power source.
　ひずみセンサ１、およびセンサ１２１～１２３は、計測対象の構造物に取り付けられる。ひずみセンサ１は、計測対象の構造物の鋼材等に貼り付けている。計測対象の構造物は、橋梁、トンネル、建物、住宅、プラント設備、パイプライン、電柱、ガス供給設備、上下水道設備、遺跡等である。 The strain sensor 1 and the sensors 121 to 123 are attached to a structure to be measured. The strain sensor 1 is attached to a steel material or the like of a structure to be measured. The structures to be measured are bridges, tunnels, buildings, houses, plant facilities, pipelines, telephone poles, gas supply facilities, water and sewage facilities, archeological sites, and the like.
　図１８は、状態を診断する橋梁に対して、センサを取り付ける例を示す概念図である。図１８に示す橋梁は、自動車が走行する高架道路橋である。高架道路橋は、上部構造と、下部構造とに分かれている。上部構造は、床版、主桁、主構、横構等を含み、下部構造は、橋台や橋脚等を含む。自動車の走行路は、上部構造の床版の上に形成される。上部構造と下部構造との間には、走行路（路面）における自動車の走行等にともなう上部構造の振動や、上部構造の変形を吸収し、下部構造にかかる荷重負荷を抑える支承が設けられている。下部構造の橋脚や、橋台は、地中に形成された基礎の上に設置されている。支承よりも上側を上部構造といい、支承よりも下側を下部構造という。ひずみセンサ１、およびセンサ１２１～１２３は、計測対象の種類の物理量が適正に計測できる位置に取り付けられる。 FIG. 18 is a conceptual diagram showing an example of attaching a sensor to a bridge for diagnosing a condition. The bridge shown in FIG. 18 is an elevated road bridge on which an automobile runs. The elevated road bridge is divided into an upper structure and a lower structure. The upper structure includes a floor slab, a main girder, a main structure, a horizontal structure, and the like, and the lower structure includes an abutment, a pier, and the like. The traveling path of the vehicle is formed on a floor slab of the superstructure. A support is provided between the upper structure and the lower structure to absorb vibration of the upper structure and deformation of the upper structure due to a vehicle running on a traveling road (road surface) and suppress a load applied to the lower structure. I have. Substructure piers and abutments are installed on foundations formed underground. The upper side of the bearing is called the upper structure, and the lower side of the bearing is called the lower structure. The strain sensor 1 and the sensors 121 to 123 are mounted at positions where the physical quantity of the type of measurement target can be measured appropriately.
　図１８では、ひずみセンサ１、およびセンサ１２１～１２３を橋梁の上部構造に取り付けた例を示しているが、下部構造に取り付けてもよい。 FIG. 18 shows an example in which the strain sensor 1 and the sensors 121 to 123 are attached to the upper structure of the bridge, but they may be attached to the lower structure.
　この例では、センサノード１１０が、予め定められた計測タイミングになると、ひずみセンサ１、およびセンサ１２１～１２３により物理量を計測する。計測タイミングは、予め定めた時刻や、時間間隔であってもよいし、予め定めた条件（温度等）を満たしたタイミング等であってもよい。 In this example, at a predetermined measurement timing, the sensor node 110 measures the physical quantity by the strain sensor 1 and the sensors 121 to 123. The measurement timing may be a predetermined time or a time interval, or may be a timing that satisfies a predetermined condition (such as temperature).
　センサノード１１０は、ひずみセンサ１、およびセンサ１２１～１２３で計測した物理量と、計測時刻とを対応付けた計測データを記憶部１１７に記憶する。また、センサノード１１０は、予め定めた送信タイミングになると、前回の送信タイミングから今回の送信タイミングまでの間に計測した物理量にかかる計測データ（記憶部１１７に記憶している計測した物理量）を診断装置に送信する。このとき、センサノード１１０は、自機を識別する識別番号を送信している。 (4) The sensor node 110 stores, in the storage unit 117, measurement data in which physical quantities measured by the strain sensor 1 and the sensors 121 to 123 are associated with measurement times. When a predetermined transmission timing is reached, the sensor node 110 diagnoses measurement data (measured physical quantity stored in the storage unit 117) relating to the physical quantity measured from the previous transmission timing to the current transmission timing. Send to device. At this time, the sensor node 110 has transmitted an identification number for identifying itself.
　診断装置は、各センサノード１１０から送信されてきた計測データを、センサノード１１０で分類して収集する。すなわち、診断装置は、センサノード１１０毎に、そのセンサノード１１０で計測された各種物理量を収集する。診断装置は、センサノード１１０毎に、収集した各種物理量を用いて、橋梁の状態を診断する。 The diagnostic device classifies and collects the measurement data transmitted from each sensor node 110 by the sensor node 110. That is, the diagnostic device collects, for each sensor node 110, various physical quantities measured by the sensor node 110. The diagnostic device diagnoses the state of the bridge for each sensor node 110 using the collected various physical quantities.
　この発明は、上記実施形態そのままに限定されるものではなく、実施段階ではその要旨を逸脱しない範囲で構成要素を変形して具体化できる。また、上記実施形態に開示されている複数の構成要素の適宜な組み合せにより種々の発明を形成できる。例えば、実施形態に示される全構成要素から幾つかの構成要素を削除してもよい。さらに、異なる実施形態に亘る構成要素を適宜組み合せてもよい。 The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements in an implementation stage without departing from the scope of the invention. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Further, constituent elements of different embodiments may be appropriately combined.
　さらに、この発明にかかる構成と上述した実施形態にかかる構成との対応関係は、以下の付記のように記載できる。　
　＜付記＞
　板状のベース板（１０）の一方の面に、フィルム状に形成されたセンサ素子（２０）を積層したひずみセンサ（１）であって、
　前記センサ素子（２０）は、圧電フィルム（２１）と、この圧電フィルム（２１）の両面に積層された電極（２２ａ、２２ｂ）とを有し、
　前記ベース板（１０）は、前記一方の面を、積層されている前記センサ素子（２０）が外側にはみ出さない大きさに形成したものであり、さらに、前記一方の面に平行である引っ張り方向における両端部に、前記センサ素子（２０）が積層されていないチャック部（１０ａ、１０ｂ）を有する、ひずみセンサ（１）。 Furthermore, the correspondence between the configuration according to the present invention and the configuration according to the above-described embodiment can be described as the following supplementary notes.
<Appendix>
A strain sensor (1) in which a sensor element (20) formed in a film shape is laminated on one surface of a plate-like base plate (10),
The sensor element (20) has a piezoelectric film (21) and electrodes (22a, 22b) laminated on both sides of the piezoelectric film (21),
The base plate (10) is formed such that the one surface is formed in such a size that the stacked sensor elements (20) do not protrude outside, and furthermore, the pulling member is parallel to the one surface. A strain sensor (1) having chuck portions (10a, 10b) in which the sensor element (20) is not stacked at both ends in the direction.
１、１Ａ～１Ｅ…ひずみセンサ
１０…ベース板
１０ａ、１０ｂ…チャック部
１１ａ…中心線
２０…センサ素子
２１…圧電フィルム
２２ａ、２２ｂ…電極
２３ａ、２３ｂ…保護膜
２４ａ…出力ライン
３０…センサカバー
４０…端子カバー
４１…樹脂
４５…出力端子
４６、４６ａ～４６ｆ…出力回路
４７…収納ケース
５０、５２…出力ケーブル
５１…接続ケーブル
１００…測定器
１０１…上端保持部
１０２…下端保持部
１０３…スライド部材 1, 1A to 1E: Strain sensor 10: Base plate 10a, 10b: Chuck portion 11a: Center line 20: Sensor element 21: Piezoelectric films 22a, 22b: Electrodes 23a, 23b: Protective film 24a: Output line 30: Sensor cover 40 ... terminal cover 41 ... resin 45 ... output terminals 46 and 46a to 46f ... output circuit 47 ... storage cases 50 and 52 ... output cable 51 ... connection cable 100 ... measuring instrument 101 ... upper end holding part 102 ... lower end holding part 103 ... slide member

Claims (11)

  1. 　板状のベース板の一方の面に、フィルム状に形成されたセンサ素子を積層したひずみセンサであって、
    　前記センサ素子は、圧電フィルムと、この圧電フィルムの両面に積層された電極とを有し、
    　前記ベース板は、前記一方の面を、積層されている前記センサ素子が外側にはみ出さない大きさに形成したものであり、さらに、前記一方の面に平行である引っ張り方向における両端部に、前記センサ素子が積層されていないチャック部を有する、ひずみセンサ。     A strain sensor in which a sensor element formed in a film shape is laminated on one surface of a plate-shaped base plate,
    The sensor element has a piezoelectric film and electrodes laminated on both sides of the piezoelectric film,
    The base plate is formed such that the one surface has a size such that the stacked sensor elements do not protrude outside, and further, at both ends in a pulling direction parallel to the one surface, A strain sensor having a chuck portion on which the sensor element is not stacked.
  2. 　前記ベース板は、前記一方の面が矩形形状であり、また前記引っ張り方向が前記一方の面の長手方向である、請求項１に記載のひずみセンサ。 The strain sensor according to claim 1, wherein the one surface of the base plate has a rectangular shape, and the pulling direction is a longitudinal direction of the one surface.
  3. 　前記ベース板は、その厚みが、前記センサ素子の厚みよりも大きい、請求項１、または２に記載のひずみセンサ。 The strain sensor according to claim 1, wherein the base plate has a thickness greater than a thickness of the sensor element.
  4. 　前記ベース板は、絶縁材料で形成されている、請求項１～３のいずれかに記載のひずみセンサ。 The strain sensor according to any one of claims 1 to 3, wherein the base plate is formed of an insulating material.
  5. 　前記ベース板には、前記一方の面に、前記センサ素子の出力ラインが接続される第１端子、および前記出力ラインが接続された前記第１端子を覆う端子カバーが取り付けられている、請求項１～４のいずれかに記載のひずみセンサ。 The first terminal to which the output line of the sensor element is connected and the terminal cover which covers the first terminal to which the output line is connected are attached to the one surface of the base plate. 5. The strain sensor according to any one of 1 to 4.
  6. 　前記端子カバーの内部には、樹脂を充填している、請求項４に記載のひずみセンサ。 The strain sensor according to claim 4, wherein the terminal cover is filled with a resin.
  7. 　前記引っ張り方向の一方の側から、前記チャック部、前記センサ素子、前記端子カバー、および前記チャック部が、この順番に並んでいる、請求項５、または６に記載のひずみセンサ。 7. The strain sensor according to claim 5, wherein the chuck portion, the sensor element, the terminal cover, and the chuck portion are arranged in this order from one side in the pulling direction.
  8. 　前記センサ素子の前記出力ラインが電気的に接続され、前記センサ素子の出力に応じた信号を出力する出力回路を有する、請求項５～７のいずれかに記載のひずみセンサ。 The strain sensor according to any one of claims 5 to 7, wherein the output line of the sensor element is electrically connected and has an output circuit that outputs a signal corresponding to the output of the sensor element.
  9. 　前記出力回路は、前記センサ素子の出力を増幅して出力するアンプ回路である、請求項８に記載のひずみセンサ。 The strain sensor according to claim 8, wherein the output circuit is an amplifier circuit that amplifies and outputs an output of the sensor element.
  10. 　前記出力回路は、前記第１端子が設けられ、前記ベース板の前記一方の面に取り付けられている、請求項８、または９に記載のひずみセンサ。 10. The strain sensor according to claim 8, wherein the output circuit includes the first terminal and is attached to the one surface of the base plate. 11.
  11. 　請求項１～１０のいずれかに記載のひずみセンサについて、前記センサ素子の前記圧電フィルムの厚さ方向に直交する方向の特性を測定する引張特性測定方法であって、
    　前記ベース板の両端部に形成されている前記チャック部を保持し、前記ベース板を長手方向に引っ張る引張力の大きさを変化させながら、前記ひずみセンサの出力を計測する、引張特性測定方法。     A tensile characteristic measuring method for measuring a characteristic of the strain sensor according to any one of claims 1 to 10 in a direction orthogonal to a thickness direction of the piezoelectric film of the sensor element,
    A tensile characteristic measuring method, comprising: holding the chuck portions formed at both ends of the base plate, and measuring an output of the strain sensor while changing a magnitude of a tensile force for pulling the base plate in a longitudinal direction.
PCT/JP2019/025029 2018-07-06 2019-06-25 Strain sensor and tensile property measurement method WO2020008939A1 (en)

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