Sensor and electronic device

Abstract

This sensor comprises: a piezoelectric film sensor that has a first main surface; and a first base material that is stretchable in a first direction parallel to the first main surface and that is disposed on the first main surface. The piezoelectric film sensor is provided with: a piezoelectric film that has a first film main surface and a second film main surface; a first electrode that is stretchable in a first direction and that is disposed on the first film main surface; and a second electrode that is stretchable in the first direction and that is disposed on the second film main surface.

Description

Sensors and Electronics

[0001] The present invention relates to a sensor and an electronic device that detects deformation of a measurement object.

[0002] Patent Document 1 describes a displacement sensor that includes an elastic body and a piezoelectric element. The elastic body is made of a high-strength polymer. The piezoelectric element is attached to the elastic body. The displacement sensor is provided on a housing. The displacement sensor detects the displacement of the housing. Specifically, the elastic body is attached to the housing. The piezoelectric element attached to the elastic body deforms as the housing deforms. The piezoelectric element generates a voltage according to the amount of displacement of the piezoelectric element.

[0003] International Publication No. 2012 / 137897

[0004] In the field of the displacement sensor described in Patent Document 1, there is a demand for a sensor that can be easily attached to a soft object to be measured or to the curved surface of an object to be measured having a curved surface. Even if an attempt is made to attach the high-strength displacement sensor described in Patent Document 1 to a soft object to be measured or to a curved surface, there is a possibility that the sensor will peel off due to strong springback.

[0005] An object of the present invention is to provide a sensor that will not peel off even when attached to a soft object to be measured or to the curved surface of an object to be measured having a curved surface.

[0006] A sensor according to one embodiment of the present invention includes a piezoelectric film sensor having a first main surface, a first substrate stretchable in a first direction parallel to the first main surface and disposed on the first main surface, a piezoelectric film having a first main surface and a second main surface, a first electrode stretchable in the first direction and disposed on the first main surface, and a second electrode stretchable in the first direction and disposed on the second main surface.

[0007] According to the sensor of one embodiment of the present invention, the sensor will not come off even when attached to a soft measurement object or to the curved surface of a measurement object having a curved surface.

[0008] FIG. 1 is a top view of the sensor 1. FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 3 is a cross-sectional view of a sensor 1A according to Modification 1. FIG. 4 is a cross-sectional view of a sensor 50 according to a comparative example. FIG. 5 is a cross-sectional view of a sensor 1B according to Modification 2. FIG. 6 is a cross-sectional view of a sensor 1C according to Modification 3. FIG. 7 is a cross-sectional view of a sensor 1D according to Modification 4. FIG. 8 is a top view showing an example of a test piece 20 and a loop stiffness measuring instrument 25. FIG. 9 is a cross-sectional view taken along line B-B in FIG. 8. FIG. 10 is a cross-sectional view showing an example of a method for preparing a test piece 20 used in the loop stiffness measuring instrument 25. FIG. 11 is a cross-sectional view showing a step of forming a loop portion 21 in the test piece 20. FIG. 12 is a plan view showing a step of applying a load to the loop portion 21 of the test piece 20. FIG. 13 is a plan view showing a step of applying a load to the loop portion 21 of the test piece 20. FIG. 14 is a block diagram showing the configuration of an electronic device 7 according to another example.

[0009] FIG. 1 is a top view of the sensor 1. FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1. The sensor 1 detects deformation of the object to be measured OB. The object to be measured OB is, for example, a soft object or an object with a curved surface. The object to be measured OB is, for example, a human arm, a human elbow, a machine arm, or the pipe of a flow meter. As an example, the sensor 1 is attached to a human elbow. In this case, the sensor 1 detects movements such as bending and straightening the person's elbow.

[0010] The sensor 1 includes a piezoelectric film sensor 10 and a first substrate 11. The piezoelectric film sensor 10 has a plate shape including a short side extending in the Y-axis direction and a long side extending in the X-axis direction. The piezoelectric film sensor 10 has a first main surface SF1 and a second main surface SF2. The second main surface SF2 faces the first main surface SF1. The first main surface SF1 and the second main surface SF2 are aligned in this order in the positive direction of the Z-axis. The first main surface SF1 is parallel to the X-axis and Y-axis directions.

[0011] In this embodiment, directions are defined as shown in Figures 1 and 2. The direction in which the piezoelectric film sensor 10 and the first substrate 11 are arranged in this order is the negative direction of the Z axis. The direction opposite to the negative direction of the Z axis is the positive direction of the Z axis. Of the directions perpendicular to the Z axis direction, the direction along the long side of the piezoelectric film sensor 10 is the X axis direction. The direction along the short side of the piezoelectric film sensor 10 is the Y axis direction.

[0012] The piezoelectric film sensor 10 includes a first electrode 100, a piezoelectric film 101, and a second electrode 102. The piezoelectric film 101 has a sheet shape with long sides extending in the X-axis direction and short sides extending in the Y-axis direction. The piezoelectric film 101 has a first film principal surface SF11 and a second film principal surface SF12. The first film principal surface SF11 and the second film principal surface SF12 are aligned in this order in the positive direction of the Z-axis.

[0013] The piezoelectric film 101 is polarized according to the amount of deformation of the piezoelectric film 101. The direction of polarization when the piezoelectric film 101 is stretched in the X-axis direction is opposite to the direction of polarization when the piezoelectric film 101 is stretched in the Y-axis direction. For example, the piezoelectric film 101 is a film formed from a chiral polymer. An example of a chiral polymer is polylactic acid (PLA), particularly poly-L-lactic acid (PLLA). PLLA, which is a chiral polymer, has a main chain with a helical structure. The piezoelectric film 101 has a piezoelectric constant of d14. As shown in FIG. 1 , the piezoelectric film 101 is uniaxially stretched to exhibit piezoelectricity in which the molecules are oriented in an orientation direction OD. The orientation direction OD forms a 45° angle with respect to the X-axis direction and the Y-axis direction. This 45° angle includes, for example, an angle of approximately 45°±10°. As a result, the piezoelectric film 101 is polarized when the piezoelectric film 101 is stretched in the X-axis direction or the Y-axis direction. The potential difference between the first film principal surface SF11 and the second film principal surface SF12 when the piezoelectric film 101 is polarized depends on the time differential value of the deformation amount of the piezoelectric film 101 due to the stretching or compression.

[0014] The first electrode (sensor electrode) 100 is, for example, a signal electrode. The first electrode 100 is fixed to the first film main surface SF11. The first electrode 100 is, for example, a conductive adhesive that is conductive and adhesive. Alternatively, the first electrode 100 is an electrode attached with an adhesive. In this embodiment, the main surface of the first electrode 100 located on the negative side of the Z axis corresponds to the first main surface SF1.

[0015] The second electrode (sensor electrode) 102 is, for example, a reference electrode. The second electrode 102 is connected to a reference potential (for example, ground potential). As shown in FIG. 2 , the second electrode 102 is fixed to the second film main surface SF12. The second electrode 102 is, for example, a conductive adhesive that is conductive and adhesive. Alternatively, the second electrode 102 may be an electrode attached with an adhesive. In this embodiment, the main surface of the second electrode 102 located on the positive side of the Z axis corresponds to the second main surface SF2.

[0016] The first substrate 11 has a plate shape including a short side extending in the Y-axis direction and a long side extending in the X-axis direction. The first substrate 11 has a third principal surface SF3 and a fourth principal surface SF4. The fourth principal surface SF4 faces the third principal surface SF3. The third principal surface SF3 and the fourth principal surface SF4 are aligned in this order in the negative direction of the Z-axis. The first substrate 11 is in contact with the piezoelectric film sensor 10. The first substrate 11 is in contact with the first electrode 100. The first substrate 11 is attached to the piezoelectric film sensor 10 by the first electrode 100, which has adhesive properties. This fixes the first substrate 11 to the piezoelectric film sensor 10.

[0017] The first substrate 11 is stretchable at least in the X-axis direction. For example, when a force in the positive direction of the X-axis and the negative direction of the X-axis (hereinafter referred to as the X-axis direction force) is applied to the first substrate 11, the first substrate 11 stretches along the X-axis direction. When the force in the X-axis direction is no longer applied to the first substrate 11, the first substrate 11 returns to its shape before stretching. The elastic modulus of such a first substrate 11 is, for example, 1000 MPa or less. The material of the first substrate 11 is, for example, an elastomeric film. Note that the first substrate 11 may stretch along the Y-axis direction when a force in the Y-axis direction is applied to the first substrate 11.

[0018] The first electrode 100 and the second electrode 102 are stretchable at least in the X-axis direction. For example, when a force in the positive direction of the X-axis and a force in the negative direction of the X-axis (hereinafter referred to as the X-axis direction force) are applied to the first electrode 100 and the second electrode 102, the first electrode 100 and the second electrode 102 stretch along the X-axis direction. When the force in the X-axis direction is no longer applied, the first electrode 100 and the second electrode 102 return to their pre-stretched shapes.

[0019] The first electrode 100 and the second electrode 102 are made of a conductive adhesive that does not contain a core material such as copper foil, etc. This allows the first electrode 100 and the second electrode 102 to have conductivity while also having stretchability in the X-axis direction.

[0020] According to the sensor 1, the first electrode 100, the second electrode 102, and the first substrate 11 are all elastic. Therefore, even if the sensor 1 is attached to a soft measurement object OB or to the curved surface of a measurement object OB having a curved surface, springback does not occur and the sensor 1 does not peel off.

[0021] Furthermore, the sensor 1 is likely to expand in accordance with the expansion of the measurement object OB, and therefore the sensor 1 can appropriately detect the deformation of the measurement object OB.

[0022] The elastic modulus of the first substrate 11 is 1000 MPa or less, which makes the sensor 1 very soft. This makes the sensor 1 more comfortable to wear.

[0023] The first substrate 11 has cushioning properties. Therefore, the first substrate 11 easily absorbs minute vibrations of the object to be measured OB. Therefore, minute vibrations generated by the object to be measured OB are not easily transmitted to the sensor 1. As a result, the sensor 1 can prevent malfunction without detecting minute vibrations.

[0024] 3 is a cross-sectional view of a sensor 1A according to Modification 1. The sensor 1A includes a piezoelectric film sensor 10A, a conductive adhesive 150, and a first substrate 11. The piezoelectric film sensor 10A includes a first electrode 100A, a piezoelectric film 101, and a second electrode 102.

[0025] The first electrode 100A is formed directly on the first film main surface SF11 of the piezoelectric film 101. The first electrode 100A is a polymer conductive material such as PEDOT (polyethylenedioxythiophene) or a thin film metal, and is formed directly on the first film main surface SF11 by a process such as printing or vapor deposition, thereby extremely reducing stray capacitance.

[0026] (Effects) Figure 4 is a cross-sectional view of a sensor 50 according to a comparative example. The sensor 50 according to the comparative example has a piezoelectric film sensor 80, a conductive tape 70, and a first substrate 90. The piezoelectric film sensor 80 has a piezoelectric film 101 and a second electrode 102. In the sensor 50 according to the comparative example, the first electrode of the piezoelectric film sensor 80 is formed by the conductive tape 70. The conductive tape 70 is a hard conductive tape having a core material.

[0027] In the comparative example, stray capacitance C occurs depending on the distance between the core material of the conductive tape 70 and the first film main surface SF11 of the piezoelectric film 101. As the thickness of the piezoelectric film 101 is reduced to increase its flexibility, the value of the stray capacitance C relative to the output of the piezoelectric film 101 increases, and the reduction in output due to the stray capacitance, which was previously negligible, becomes more pronounced.

[0028] In contrast, the first electrode 100A of the sensor 1A of the first modification is formed directly on the first film main surface SF11 of the piezoelectric film 101. Therefore, the stray capacitance C in the comparative example is extremely small. This allows the sensor 1A to prevent the output reduction that occurs in conventional sensor devices.

[0029] 5 is a cross-sectional view of a sensor 1B according to Modification 2. The sensor 1B includes a piezoelectric film sensor 10B, a conductive adhesive 150, and a first substrate 11. The piezoelectric film sensor 10B includes a first electrode 100A, a piezoelectric film 101, and a second electrode 102A.

[0030] The second electrode 102A is formed directly on the second film main surface SF12 of the piezoelectric film 101. The second electrode 102A is a polymer conductive material such as PEDOT (polyethylenedioxythiophene) or a thin film metal, and is formed directly on the second film main surface SF12 by a process such as printing or vapor deposition.

[0031] In this way, both the first electrode 100A and the second electrode 102A may be formed directly on the main surface of the piezoelectric film 101. That is, the first electrode may be formed directly on the main surface of the first film, or the second electrode may be formed directly on the main surface of the second film.

[0032] 6 is a cross-sectional view of a sensor 1C according to Modification 3. The sensor 1C includes a piezoelectric film sensor 10B, a conductive adhesive 150, a conductive adhesive 151, a first substrate 11, and a second substrate 15.

[0033] The second substrate 15 is attached to the second main surface SF2 of the piezoelectric film sensor 10B. Therefore, in this modification 3, the piezoelectric film sensor 10B is located between the first substrate 11 and the second substrate 15. The second substrate 15 has stretchability in the X-axis direction or the Y-axis direction. The elastic modulus of the second substrate 15 is 1000 MPa or less. The material of such second substrate 15 is an elastomer film, similar to the first substrate 11. The other configurations of the second substrate 15 are the same as those of the first substrate 11, and therefore will not be described.

[0034] (Effect) In sensor 1C, elastic substrates (first substrate 11, second substrate 15) are disposed on both the positive side of piezoelectric film sensor 10B along the Z axis and the negative side of piezoelectric film sensor 10B along the Z axis. This achieves a balance between the stress (first stress) applied to sensor 1C by second substrate 15 on the positive side of piezoelectric film sensor 10B along the Z axis and the stress (second stress) applied to sensor 1C by first substrate 11 on the negative side of piezoelectric film sensor 10B along the Z axis (the first stress and the second stress tend to cancel each other out). This makes sensor 1C less likely to warp.

[0035] Furthermore, for example, if the piezoelectric film sensor 10B were to be directly mounted on a printed circuit board or the like, resin potting may be used, but cracks may occur at the mounting boundary. The piezoelectric film sensor 10B of the sensor 1C is covered by the soft second substrate 15 and first substrate 11. Therefore, even when mounted using potting, large forces are unlikely to be generated at the mounting boundary due to the contraction of the second substrate 15 and the first substrate 11. Cracks are unlikely to occur at the mounting boundary. As a result, the reliability of the sensor 1C is likely to be improved.

[0036] 7 is a cross-sectional view of a sensor 1D according to Modification 4. The sensor 1D has a piezoelectric film sensor 10B, a conductive adhesive 150, a conductive adhesive 151, a first substrate 11, a fixing member 171, and a second substrate 15.

[0037] The fixing member 171 is disposed on the fourth main surface SF4. The fixing member 171 fixes the first base material 11 to the measurement object OB. The fixing member 171 is, for example, a double-sided tape such as an OCA (Optical Clear Adhesive).

[0038] If the fixing member 171 is a double-sided tape, it is preferable that the fixing member 171 does not include a core material such as a film. If the fixing member 171 includes a core material such as a film, the elastic modulus of the fixing member 171 will be higher than if there is no core material. This makes it easier for strong springback to occur in the sensor, increasing the possibility that the sensor will peel off from the measurement object OB.

[0039] (Effect) Since the sensor 1D of variant example 4 is fixed to the object to be measured OB by the fixing member 171, the risk of the sensor 1D peeling off is further reduced even when the sensor 1D is attached to a soft object to be measured OB or the curved surface of an object to be measured OB having a curved surface.

[0040] (Method of Measuring Loop Stiffness Value) Fig. 8 is a top view showing an example of the test piece 20 and the loop stiffness measuring instrument 25. Fig. 9 is a cross-sectional view taken along the line B-B shown in Fig. 8. Fig. 10 is a cross-sectional view showing an example of a method of preparing the test piece 20 used in the loop stiffness measuring instrument 25. Fig. 11 is a cross-sectional view showing a step of forming the loop portion 21 in the test piece 20. Figs. 12 and 13 are plan views showing a step of applying a load to the loop portion 21 of the test piece 20.

[0041] The loop stiffness value is a parameter that indicates the stiffness of a film. The film is not limited to a single-layer film, but may be a laminate of films or plates, etc. Sensors 1, 1A to 1D are an example of a laminate of films or plates, etc. Below, a method for measuring the loop stiffness value of sensors 1, 1A to 1D will be described with reference to FIGS. 8 to 13.

[0042] As shown in Fig. 8, the test piece 20 is a rectangular film having long and short sides. In the present application, the length L1 of the long side of the test piece 20 is set to 60 mm, and the length L2 of the short side is set to 10 mm. As the loop stiffness measuring instrument 25, for example, a No. 581 Loop Stiffness Tester (registered trademark) LOOP STIFFNESS TESTER DA type manufactured by Toyo Seiki Seisaku-sho, Ltd. can be used.

[0043] The loop stiffness measuring device 25 has a pair of chuck portions 26 for gripping a pair of ends in the long side direction of the test specimen 20, and a support member 27 for supporting the chuck portions 26. The chuck portions 26 include a first chuck 261 and a second chuck 262. In the state shown in FIGS. 8 and 9 , the test specimen 20 is placed on the pair of first chucks 261, and the second chuck 262 has not yet gripped the test specimen 20 between itself and the first chuck 261. As will be described later, during measurement, the test specimen 20 is gripped between the first chuck 261 and the second chuck 262 of the chuck portions 26.

[0044] A method for measuring the loop stiffness value of the test specimen 20 using the loop stiffness measuring device 25 will be described. First, as shown in FIGS. 8 and 9 , the test specimen 20 is placed on the first chuck 261 of a pair of chuck portions 26 arranged with a gap L3 therebetween. In the present application, the gap L3 is set so that the length of the loop portion 21 (hereinafter also referred to as the loop length), which will be described later, is 20 mm. Next, as shown in FIG. 10 , the second chuck 262 is placed on the test specimen 20 so that the end of the long side of the test specimen 20 is gripped between the second chuck 262 and the first chuck 261.

[0045] Next, as shown in FIG. 11 , at least one of the pair of chucks 26 is slid on the support member 27 in a direction that reduces the distance between the pair of chucks 26. This allows a loop 21 having a loop length of 20 mm to be formed on the test specimen 20. The loop length of the loop 21 is the length of the test specimen 20 between position P1, where the surface of one second chuck 262 on the loop 21 side intersects with the test specimen 20, and position P2, where the surface of the other second chuck 262 on the loop 21 side intersects with the test specimen 20. If the thickness of the test specimen 20 is ignored, the distance L3 is calculated by adding 2×t to the length of the loop 21, where t is the thickness of the second chuck 262 of the chuck 26.

[0046] 12, the posture of the chuck portion 26 is adjusted so that the protruding direction of the loop portion 21 relative to the chuck portion 26 is horizontal. For example, the posture of the chuck portion 26 supported by the support member 27 is adjusted by moving the support member 27 so that the normal direction of the support member 27 is horizontal. In the example shown in FIG. 12, the protruding direction of the loop portion 21 coincides with the thickness direction of the chuck portion 26 and coincides with the negative direction of the Y axis.

[0047] Additionally, the load cell 28 is prepared at a position deflected toward the tip of the loop portion 21 in the direction of protrusion of the loop portion 21. At this time, the load cell 28 is positioned at a distance Y1 away from the second chuck 262 in the direction of protrusion of the loop portion 21. Next, the load cell 28 is moved toward the loop portion 21 of the test specimen 20 at a speed V by a distance Y2 shown in FIG. 12. The distance Y2 is set so that the load cell 28 presses the loop portion 21 toward the chuck portion 26. In this application, the distance Y2 is set to 2 mm. In this case, the distance Y3 between the load cell 28 and the second chuck 262 of the chuck portion 26 when the load cell 28 presses the loop portion 21 toward the chuck portion 26 is Y1-Y2=18 mm. The speed V at which the load cell 28 is moved is set to 0.4 mm / sec.

[0048] 13, the load cell 28 is moved a distance Y2 toward the chuck portion 26, and with the load cell 28 pressing into the loop portion 21 of the test piece 20, the value of the load applied to the load cell 28 from the loop portion 21 becomes stable, and then the value of the load is recorded. The value of the load thus obtained is used as the loop stiffness value of the film constituting the test piece 20. In this application, unless otherwise specified, the environment during the measurement of loop stiffness is a temperature of 25°C and a relative humidity of 50%.

[0049] Preferably, the loop stiffness value of the sensors 1, 1A-1D is 0.005 N or more and 2 N or less. If the loop stiffness value of the sensors 1, 1A-1D is less than 0.005 N, it is difficult to maintain the shape of the sensors 1, 1A-1D, and it is difficult to attach the sensors 1, 1A-1D to the object to be measured OB. Furthermore, if the loop stiffness value of the sensors 1, 1A-1D is greater than 2 N, when the radius of curvature of a portion of the curved surface of the object to be measured OB is small, warping of the sensors 1, 1A-1D may cause the sensors 1, 1A-1D to peel off when the sensors are attached to the curved surface. Therefore, it is preferable that the loop stiffness value of the sensors 1, 1A-1D is 0.005 N or more and 2 N or less. A loop stiffness value of 0.005 N corresponds to a 10 μm-thick PET (polyethylene terephthalate) film. A loop stiffness value of 1 N corresponds to a PET (polyethylene terephthalate) film having a thickness of 110 μm.

[0050] Preferably, the loop stiffness value of sensors 1, 1A-1D is 0.005 N or more and 0.1 N or less. If the loop stiffness value of sensors 1, 1A-1D is greater than 0.1 N, when the measurement object OB is an elastic object such as rubber other than a human body and the radius of curvature of a portion of the curved surface of the measurement object OB is small, warping of sensors 1, 1A-1D may cause sensors 1, 1A-1D to peel off when attached to the curved surface. An example of a measurement object OB that is an elastic object such as rubber other than a human body is a rubber hose, such as an industrial rubber hose. Therefore, the loop stiffness value of sensors 1, 1A-1D is preferably 0.005 N or more and 0.1 N or less.

[0051] Preferably, the loop stiffness value of sensors 1, 1A to 1D is 0.005 N or more and 0.2 N or less. If the loop stiffness value of sensors 1, 1A to 1D is greater than 0.2 N, it is difficult to detect bending and straightening movements when the object to be measured OB is a human body and the radius of curvature of a portion of the curved surface of the object to be measured OB is small. Such an object to be measured OB is a joint such as a human elbow. Therefore, the loop stiffness value of sensors 1, 1A to 1D is preferably 0.005 N or more and 0.2 N or less.

[0052] (Other Examples) Fig. 14 is a block diagram showing the configuration of an electronic device 7 according to another example. The electronic device 7 includes a sensor 1 and an arithmetic circuit 9 that receives a signal from the sensor 1. The arithmetic circuit 9 may be configured as a separate component from the sensor 1, or may be mounted on the first substrate 11 of the sensor 1. Alternatively, the arithmetic circuit 9 may be mounted so as to be sandwiched between the first substrate 11 and the second substrate 15 shown in Fig. 6 or 7. In this case, in addition to the piezoelectric film sensor 10, the arithmetic circuit 9 can also be attached to the object to be measured OB. This improves ease of use as a flexible sensor.

[0053] The description of the present embodiment should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined not by the above-described embodiments but by the claims. Furthermore, the scope of the present invention includes the scope equivalent to the claims.

[0054] The sensors according to the present invention are not limited to the sensors 1, 1A to 1D, and can be modified within the scope of the gist thereof. The configurations of the sensors 1, 1A to 1D may be combined in any manner.

[0055] The X-axis, Y-axis, and Z-axis directions are defined for the purpose of explanation. Therefore, the X-axis, Y-axis, and Z-axis directions when sensors 1, 1A to 1D are actually used do not necessarily have to match the X-axis, Y-axis, and Z-axis directions in each embodiment and each modified example.

[0056] The present invention has the following structure:

[0057] <1> A sensor comprising: a piezoelectric film sensor having a first main surface; and a first substrate having stretchability in a first direction parallel to the first main surface and disposed on the first main surface, wherein the piezoelectric film sensor comprises: a piezoelectric film having a first film main surface and a second film main surface; a first electrode having stretchability in the first direction and disposed on the first film main surface; and a second electrode having stretchability in the first direction and disposed on the second film main surface.

[0058] <2> The sensor according to <1>, wherein the first electrode is formed directly on the main surface of the first film, or the second electrode is formed directly on the main surface of the second film.

[0059] <3> The sensor according to <1> or <2>, further comprising a second substrate having stretchability in the first direction, the piezoelectric film sensor having a second main surface, and the second substrate being attached to the second main surface.

[0060] <4> The sensor according to any one of <1> to <3>, wherein the first electrode constitutes the first main surface, the first electrode is a signal electrode, and the second electrode is a reference electrode connected to a reference potential.

[0061] <5> The sensor according to any one of <1> to <4>, further comprising a fixing member that fixes the measurement object and the piezoelectric film sensor.

[0062] <6> The sensor according to any one of <1> to <5>, wherein the material of the first substrate is an elastomer film.

[0063] <7> An electronic device comprising: the sensor according to any one of <1> to <6>; and an arithmetic circuit that receives a signal from the sensor.

[0064] 1: Sensor 1A: Sensor 1B: Sensor 1C: Sensor 1D: Sensor 7: Electronic device 9: Arithmetic circuit 10: Piezoelectric film sensor 10A: Piezoelectric film sensor 10B: Piezoelectric film sensor 11: First substrate 15: Second substrate 20: Test piece 21: Loop portion 25: Loop stiffness measuring device 26: Chuck portion 27: Support member 28: Load cell 50: Sensor 70: Conductive tape 80: Piezoelectric film sensor 90: First substrate 100: First electrode 100A: First electrode 101: Piezoelectric film 102: Second electrode 102A: Second electrode 111: Piezoelectric film 150: Conductive adhesive 151: Conductive adhesive 171: Fixing member 261 : First chuck 262 : Second chuck OB : Measurement object SF1 : First main surface SF2 : Second main surface SF11 : First film main surface SF12 : Second film main surface SF3 : Third main surface SF4 : Fourth main surface

Claims

1. A sensor comprising: a piezoelectric film sensor having a first main surface; and a first substrate having elasticity in a first direction parallel to the first main surface and arranged on the first main surface, wherein the piezoelectric film sensor comprises: a piezoelectric film having a first film main surface and a second film main surface; a first electrode having elasticity in the first direction and arranged on the first film main surface; and a second electrode having elasticity in the first direction and arranged on the second film main surface.

2. The sensor according to claim 1, wherein the first electrode is formed directly on the main surface of the first film, or the second electrode is formed directly on the main surface of the second film.

3. A sensor as described in claim 1 or claim 2, further comprising a second substrate having elasticity in the first direction, the piezoelectric film sensor having a second main surface, and the second substrate being attached to the second main surface.

4. A sensor as described in any one of claims 1 to 3, wherein the first electrode constitutes the first main surface, the first electrode is a signal electrode, and the second electrode is a reference electrode connected to a reference potential.

5. The sensor according to any one of claims 1 to 4, further comprising a fixing member for fixing the measurement object and the piezoelectric film sensor.

6. The sensor according to any one of claims 1 to 5, wherein the material of the first substrate is an elastomer film.

7. The sensor according to any one of claims 1 to 6, wherein the loop stiffness value of the sensor is equal to or greater than 0.005 N and equal to or less than 2 N.

8. The sensor according to any one of claims 1 to 6, wherein the loop stiffness value of the sensor is equal to or greater than 0.005 N and equal to or less than 0.1 N.

9. The sensor according to any one of claims 1 to 6, wherein the loop stiffness value of the sensor is equal to or greater than 0.005 N and equal to or less than 0.2 N.

10. An electronic device comprising: a sensor according to any one of claims 1 to 9; and an arithmetic circuit that receives a signal from the sensor.

Images