Sensor

Abstract

This sensor is provided with: a piezoelectric film sensor having a first main surface and a second main surface facing the first main surface; a first stretchable substrate that is stretchable in a first direction parallel to the first main surface, has a third main surface and a fourth main surface facing the third main surface, and is in contact with the piezoelectric film sensor; a stretchable electrode wiring that is stretchable in the first direction, is disposed on the third main surface, and is in contact with the first main surface; and an adhesive disposed on the fourth main surface, the thickness of the piezoelectric film sensor being smaller than the sum of the thickness of the stretchable electrode wiring, the thickness of the first stretchable substrate, and the thickness of the adhesive.

Description

Technical Field

[0001] This invention relates to a sensor for detecting and measuring the deformation of an object. Background Technology

[0002] Patent Document 1 describes a displacement sensor comprising an elastomer and a piezoelectric element. The elastomer is formed of a high-strength polymer. The piezoelectric element is mounted on the elastomer. The displacement sensor is disposed in a housing. The displacement sensor detects the displacement of the housing. Specifically, the elastomer is mounted on the housing. The piezoelectric element mounted on the elastomer deforms with the deformation of the housing. The piezoelectric element generates a voltage corresponding to the amount of displacement of the piezoelectric element.

[0003] [Existing technical documents]

[0004] [Patent Literature]

[0005] Patent Document 1: International Publication No. 2012 / 137897 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the field of displacement sensors described in Patent Document 1, a sensor that is easy to mount onto a soft measuring object or the curved surface of a measuring object is desirable. Even if a high-strength displacement sensor as described in Patent Document 1 is attached to a soft or curved measuring object, it may peel off due to strong rebound.

[0008] The object of the present invention is to provide a sensor that will not peel off even when mounted on a soft measuring object or a measuring object with a curved surface.

[0009] [Methods used to solve problems]

[0010] One embodiment of the present invention comprises a sensor having: a piezoelectric film sensor having a first main surface and a second main surface opposite to the first main surface; a first stretchable substrate having stretchability in a first direction parallel to the first main surface, having a third main surface and a fourth main surface opposite to the third main surface and in contact with the piezoelectric film sensor; a stretchable electrode wiring having stretchability in the first direction, disposed on the third main surface and in contact with the first main surface; and an adhesive disposed on the fourth main surface, wherein the thickness of the piezoelectric film sensor is thinner than the sum of the thickness of the stretchable electrode wiring, the thickness of the first stretchable substrate, and the thickness of the adhesive.

[0011] [Invention Effects]

[0012] According to one embodiment of the present invention, the sensor will not peel off even when mounted on a soft measuring object or the curved surface of a measuring object. Attached Figure Description

[0013] Figure 1 This is a top view of sensor 1 according to the first embodiment.

[0014] Figure 2 yes Figure 1 The AA section view shown.

[0015] Figure 3 This is a top view of sensor 1a in variant example 1.

[0016] Figure 4 yes Figure 3 The AA section view shown.

[0017] Figure 5 This is a top view of sensor 1b in variant example 2.

[0018] Figure 6 yes Figure 5 The AA section view shown.

[0019] Figure 7 This is a top view of sensor 1c in variant example 3.

[0020] Figure 8 yes Figure 7 The AA section view shown.

[0021] Figure 9 This is an exploded stereoscopic view of sensor 1d in variation example 4.

[0022] Figure 10 This is an exploded perspective view of sensor 1e in variant example 5. Detailed Implementation

[0023] [First Embodiment]

[0024] Hereinafter, the sensor 1 of the first embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a top view of sensor 1 according to the first embodiment. Figure 2 yes Figure 1 The AA section view shown.

[0025] In this embodiment, such as Figure 1 and Figure 2 The orientation is defined as shown. The direction in which the piezoelectric film sensor 10 and the first stretchable substrate 11 are arranged sequentially is the negative direction of the Z-axis. The opposite direction of the negative Z-axis is the positive Z-axis. The direction orthogonal to the Z-axis, along the long side of the piezoelectric film sensor 10, is the X-axis direction. Figure 2As shown, the portion of the telescopic electrode wiring 12 that contacts the piezoelectric membrane sensor 10 and the portion that does not contact the piezoelectric membrane sensor 10 are arranged sequentially in the positive direction of the X-axis. The opposite direction of the positive X-axis is the negative X-axis. The direction along the short side of the piezoelectric membrane sensor 10 is the Y-axis direction.

[0026] Sensor 1 detects the deformation of the object OB. The object OB is, for example, a soft object or an object with a curved surface. Examples of the object OB include a human arm, a human elbow, a mechanical arm, a flow meter tube, etc. As an example, sensor 1 is mounted on a human elbow. In this case, sensor 1 detects the flexion and extension movements of the human elbow. Sensor 1 includes a piezoelectric film sensor 10, a first telescopic substrate 11, telescopic electrode wiring 12, and an adhesive 13.

[0027] like Figure 1 and Figure 2 As shown, the piezoelectric film sensor 10 has a plate shape comprising a short side extending along the Y-axis and a long side extending along the X-axis. The piezoelectric film sensor 10 has a first main surface SF1 and a second main surface SF2. The second main surface SF2 is opposite to the first main surface SF1. The first main surface SF1 and the second main surface SF2 are arranged sequentially in the positive direction of the Z-axis. The first main surface SF1 is parallel to both the X-axis and Y-axis directions. Figure 2 As shown, the piezoelectric film sensor 10 includes a first electrode 100, a piezoelectric film 101, and a second electrode 102.

[0028] like Figure 1 and Figure 2 As shown, the piezoelectric film 101 has a sheet shape comprising a long side extending along the X-axis and a short side extending along the Y-axis. The piezoelectric film 101 has a first film main surface SF11 and a second film main surface SF12. The first film main surface SF11 and the second film main surface SF12 are arranged sequentially in the positive direction of the Z-axis.

[0029] The piezoelectric film 101 is polarized according to the amount of deformation of the piezoelectric film 101. The polarization direction of the piezoelectric film 101 when elongated along the X-axis is opposite to the polarization direction when elongated along the Y-axis. For example, the piezoelectric film 101 is a film formed of a chiral polymer. Chiral polymers are, for example, polylactic acid (PLA), especially L-type polylactic acid (PLLA). The backbone of PLLA, composed of chiral polymers, has a helical structure. The piezoelectric film 101 has a piezoelectric constant of d14. Figure 1As shown, the piezoelectric film 101 exhibits piezoelectricity with its molecules oriented along the orientation direction OD when uniaxially stretched. The orientation direction OD forms an angle of 45 degrees with respect to the X-axis and Y-axis directions. This 45-degree angle includes, for example, approximately 45 degrees ± 10 degrees. Thus, the piezoelectric film 101 is polarized by elongation along the X-axis or Y-axis. The potential difference between the first principal surface SF11 and the second principal surface SF12 during polarization depends on the time derivative of the deformation of the piezoelectric film 101 caused by elongation or compression.

[0030] The first electrode (sensor electrode) 100 is, for example, a signal electrode. Figure 2 As shown, the first electrode 100 is fixed to the first membrane main surface SF11. The first electrode 100 is, for example, a conductive strip with conductivity and adhesion. 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.

[0031] The second electrode (sensor electrode) 102 is, for example, a reference electrode. The second electrode 102 is connected to a reference potential (e.g., ground potential). Figure 2 As shown, the second electrode 102 is fixed to the second membrane main surface SF12. The second electrode 102 is, for example, a conductive strip with conductivity and adhesion. 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.

[0032] like Figure 1 and Figure 2 As shown, the first telescopic substrate 11 has a plate shape comprising a short side extending along the Y-axis and a long side extending along the X-axis. The first telescopic substrate 11 has a third main surface SF3 and a fourth main surface SF4. The fourth main surface SF4 is opposite to the third main surface SF3. The third main surface SF3 and the fourth main surface SF4 are arranged sequentially in the negative direction of the Z-axis. The first telescopic substrate 11 contacts the piezoelectric film sensor 10 via the telescopic electrode wiring 12 (described later). The first telescopic substrate 11 contacts the first electrode 100 via the telescopic electrode wiring 12 (described later). The first telescopic substrate 11 is adhered to the piezoelectric film sensor 10 using the adhesive first electrode 100 and the telescopic electrode wiring 12 (described later). Thus, the first telescopic substrate 11 is fixed to the piezoelectric film sensor 10.

[0033] The first stretchable substrate 11 is stretchable at least in the X-axis direction. For example, when a force (hereinafter referred to as the force in the X-axis direction) is applied to the first stretchable substrate 11 in both the positive and negative directions toward the X-axis, the first stretchable substrate 11 elongates along the X-axis direction. When the force in the X-axis direction is no longer applied to the first stretchable substrate 11, the first stretchable substrate 11 returns to its shape before elongation. The elastic modulus of such a first stretchable substrate 11 is, for example, 1000 MPa or less. The material of the first stretchable substrate 11 is, for example, an elastic system film. Alternatively, when a force in the Y-axis direction is applied to the first stretchable substrate 11, the first stretchable substrate 11 may also elongate along the Y-axis direction.

[0034] The telescopic electrode wiring 12 is disposed on the third main surface SF3 of the first telescopic substrate 11. The telescopic electrode wiring 12 is a polymer conductive material such as PEDOT (polyethylene dioxythiophene) or a thin film metal. The telescopic electrode wiring 12 is formed directly on the third main surface SF3, for example, by processes such as printing or vapor deposition. Hereinafter, in this embodiment, the electrode formed directly on the substrate will be described as PEDOT or thin film metal formed by processes such as printing or vapor deposition. The telescopic electrode wiring 12 is in contact with the first main surface SF1. The telescopic electrode wiring 12 is fixed to the first main surface SF1 by the first electrode 100, which is an adhesive conductive strip. The telescopic electrode wiring 12 is electrically connected to the first electrode 100.

[0035] The telescopic electrode wiring 12 is telescopic at least in the X-axis direction. Therefore, similar to the first telescopic substrate 11, the telescopic electrode wiring 12 elongates in the X-axis direction when a force is applied in the X-axis direction. When no longer a force is applied in the X-axis direction, the telescopic electrode wiring 12 returns to its original shape before elongation. Of course, the telescopic electrode wiring 12 can also elongate along the Y-axis direction when a force is applied in the Y-axis direction.

[0036] Adhesive 13 is disposed on the fourth main surface SF4. Adhesive 13 fixes the first stretchable substrate 11, the stretchable electrode wiring 12, and the piezoelectric film sensor 10 to the object being measured OB. Adhesive 13 is, for example, double-sided tape such as OCA (Optically Clear Adhesive).

[0037] In this embodiment, the thickness DS1 of the piezoelectric film sensor 10 is thinner than the sum of the thicknesses of the telescopic electrode wiring 12, the first telescopic substrate 11, and the adhesive 13 (see reference). Figure 2Specifically, the thickness DS1 of the piezoelectric film sensor 10 is the length between the first main surface SF1 and the second main surface SF2. The thickness of the telescopic electrode wiring 12 is the length between the two main surfaces of the telescopic electrode wiring 12. The thickness of the first telescopic substrate 11 is the length between the third main surface SF3 and the fourth main surface SF4. The thickness of the adhesive 13 is the length between the two main surfaces of the adhesive 13.

[0038] (Effect)

[0039] According to sensor 1, even if sensor 1 is mounted on a soft measuring object OB or the curved surface of the measuring object OB, it will not peel off. Hereinafter, the displacement sensor described in Patent Document 1 (hereinafter referred to as Comparative Example 1) will be compared and explained with sensor 1 of this embodiment.

[0040] The substrate of Comparative Example 1 has a high modulus of elasticity. Therefore, when Comparative Example 1 is bent, the magnitude of the stress applied to it (the force achieved by springback) tends to increase. Consequently, when Comparative Example 1 is mounted on a soft and highly deformable test object (hereinafter referred to as the first test object), a strong springback occurs in Comparative Example 1 when the first test object deforms significantly, potentially causing Comparative Example 1 to peel off from the first test object. Therefore, even if Comparative Example 1 is mounted on the first test object, the likelihood of peeling is high. Similarly, when Comparative Example 1 is mounted on the curved surface of a test object (hereinafter referred to as the second test object), a strong springback occurs in Comparative Example 1, potentially causing Comparative Example 1 to peel off from the second test object. Therefore, it is difficult to use Comparative Example 1 mounted on either the first or second test object.

[0041] On the other hand, in sensor 1, the first stretchable substrate 11 and the stretchable electrode wiring 12 are stretchable in the X-axis direction, making them very easy to bend. Furthermore, the thickness DS1 of the piezoelectric film sensor 10 is thinner than the combined thickness DS2 of the first stretchable substrate 11, the stretchable electrode wiring 12, and the adhesive 13. Therefore, the piezoelectric film sensor 10 easily deforms in response to the deformation of the first stretchable substrate 11, the stretchable electrode wiring 12, and the adhesive 13. Sensor 1 easily elongates with the elongation of the first object being measured. Therefore, even when the first object being measured is significantly bent or deformed, sensor 1 is not easily peeled off from the first object being measured. Additionally, sensor 1 is easily mounted on the curved surface of the second object being measured.

[0042] Furthermore, sensor 1 readily elongates as the first object being measured stretches. Therefore, sensor 1 can accurately detect the deformation of the first object being measured. Similarly, sensor 1 can accurately detect the deformation of the second object being measured.

[0043] Furthermore, the elastic modulus of the first stretchable substrate 11 is less than 1000 MPa. Therefore, the sensor 1 is much softer than Comparative Example 1. Consequently, the wearing comfort of the sensor 1 is easily improved.

[0044] The first stretchable substrate 11, the stretchable electrode wiring 12, and the adhesive 13 are stretchable and have cushioning properties. Therefore, the first stretchable substrate 11, the stretchable electrode wiring 12, and the adhesive 13 readily absorb minute vibrations of the object being measured, OB. Consequently, minute vibrations generated by the object being measured, OB, are not easily transmitted to the sensor 1. As a result, the sensor 1 will not detect minute vibrations, thus preventing malfunctions.

[0045] [Variation Example 1]

[0046] Hereinafter, the sensor 1a of the modified example 1 of the sensor 1 will be described with reference to the accompanying drawings. Figure 3 This is a top view of sensor 1a in variant example 1. Figure 4 yes Figure 3 The AA section view shown. Figure 3 In the middle, the following was omitted. Figure 4 The description of the second stretchable substrate 20 and the second electrode 102a is shown. In this modified example 1, as... Figure 3 As shown, the reference electrode 25, signal electrode 26, and reference electrode 24 are arranged in the positive direction of the Y-axis. The opposite direction of the positive Y-axis is the negative Y-axis.

[0047] like Figure 3 and Figure 4 As shown, sensor 1a differs from sensor 1 in that it has a telescopic electrode wiring 12a that is different from the telescopic electrode wiring 12; it also has a second telescopic substrate 20, a third telescopic substrate 21, reference electrodes 22-25 and a signal electrode 26; it also has an insulator 27; and it has a piezoelectric film sensor 10a that is different from the piezoelectric film sensor 10. The piezoelectric film sensor 10a differs from the piezoelectric film sensor 10 in that it has a second electrode 102a that is different from the second electrode 102.

[0048] like Figure 3 and Figure 4 As shown, when viewed along the Z-axis, the signal electrode 26 has a rectangular shape. The signal electrode 26 is formed in the Y-axis direction near the center of the third main surface SF3 and at its end in the positive X-axis direction of the third main surface SF3. The signal electrode 26 is located on the positive X-axis side of the piezoelectric membrane sensor 10a.

[0049] like Figure 3 and Figure 4As shown, when viewed along the Z-axis, reference electrodes 24 and 25 are rectangular in shape. Reference electrodes 24 and 25 are formed at the ends of the third main surface SF3 in the positive X-axis direction. Reference electrodes 24 and 25 are located on the positive X-axis side of the piezoelectric membrane sensor 10a. Reference electrode 24 is located on the positive Y-axis side compared to the signal electrode 26. Reference electrode 25 is located on the negative Y-axis side compared to the signal electrode 26. Reference electrodes 24 and 25 are connected to a reference potential. Neither reference electrode 24 nor 25 is electrically connected to the signal electrode 26.

[0050] like Figure 3 and Figure 4 As shown, when viewed along the Z-axis, the reference electrode 23 has a rectangular shape. The reference electrode 23 also extends along the Y-axis. The reference electrode 23 is formed at the end of the third main surface SF3 in the negative X-axis direction. The reference electrode 23 is located on the negative X-axis side of the piezoelectric membrane sensor 10a. Figure 4 In the original design, reference electrode 23 is not in contact with the second electrode 102a. However, in actual use of sensor 1a, reference electrode 23 is in contact with the second electrode 102a. Therefore, reference electrode 23 is electrically connected to the second electrode 102a. Reference electrode 23 is not electrically connected to signal electrode 26.

[0051] like Figure 3 As shown, the telescopic electrode wiring 12a differs from the telescopic electrode wiring 12 in that it includes signal electrode wiring 120a and reference electrode wirings 121a and 122a.

[0052] Signal electrode wiring 120a is formed near the center of the third principal surface SF3 in the Y-axis direction. Signal electrode wiring 120a has a shape extending along the X-axis direction. For example... Figure 4 As shown, signal electrode wiring 120a is fixed to the first electrode 100. Signal electrode wiring 120a is electrically connected to signal electrode 26 and the first electrode 100. Signal electrode wiring 120a is flexible in the X-axis direction.

[0053] Reference electrode wiring 121a is formed on the third main surface SF3. Reference electrode wiring 121a is located on the positive side of the Y-axis of the piezoelectric film sensor 10a and signal electrode wiring 120a. Reference electrode wiring 121a has a shape extending along the X-axis direction. Reference electrode wiring 121a is electrically connected to reference electrode 23 and reference electrode 24. Figure 3 As shown, the reference electrode wiring 121a is not electrically connected to the signal electrode wiring 120a. The reference electrode wiring 121a is flexible in the X-axis direction.

[0054] Reference electrode wiring 122a is formed on the third main surface SF3. Reference electrode wiring 122a is located on the negative side of the Y-axis of the piezoelectric film sensor 10a and signal electrode wiring 120a. Reference electrode wiring 122a has a shape extending along the X-axis direction. Reference electrode wiring 122a is electrically connected to reference electrode 23 and reference electrode 25. Figure 3 As shown, the reference electrode wiring 122a is not electrically connected to the signal electrode wiring 120a. The reference electrode wiring 122a is flexible in the X-axis direction.

[0055] like Figure 4 As shown, the second telescopic substrate 20 has a plate shape including a first main surface SF1a and a second main surface SF2a. The first main surface SF1a and the second main surface SF2a are arranged sequentially in the positive direction of the Z-axis. The entire surface of the first main surface SF1a of the second telescopic substrate 20 is covered by the second electrode 102a.

[0056] The second stretchable substrate 20 is adhered to the second main surface SF2 of the piezoelectric film sensor 10a. Therefore, in this modified example 1, the piezoelectric film sensor 10a is located between the first stretchable substrate 11 and the second stretchable substrate 20. The second stretchable substrate 20 is stretchable in the X-axis direction. The elastic modulus of the second stretchable substrate 20 is 1000 MPa or less. The material of this second stretchable substrate 20 is the same as that of the first stretchable substrate 11, which is an elastic film system. The other structures of the second stretchable substrate 20 are the same as those of the first stretchable substrate 11, and therefore are omitted from the description.

[0057] The area of ​​the main surface of the second electrode 102a is larger than the area of ​​the first main surface SF1 or the area of ​​the second main surface SF2 of the piezoelectric film 101. In this modified example, the second electrode 102a is adhered to the second stretchable substrate 20. The second electrode 102a does not contain a core material such as copper foil, but is a conductive adhesive that has conductivity in the Z-axis direction by using conductive fillers oriented in the Z-axis direction. Thus, the second electrode 102a has conductivity in the Z-axis direction and stretchability in the X-axis direction.

[0058] However, if the conductive filler is oriented towards the Z-axis direction, it can sometimes lead to a decrease in the conductivity of the second electrode 102a in the X-axis direction. Therefore, the second electrode 102a of the sensor 1a ensures conductivity in the X-axis direction by being electrically connected to the reference electrode wirings 121a and 122a extending along the X-axis direction.

[0059] A reference electrode 22 is disposed on the fourth main surface SF4 of the first telescopic substrate 11. The reference electrode 22 covers approximately the entire surface of the fourth main surface SF4. Figure 4In the original sensor 1a, reference electrode 22 is not in contact with the second electrode 102a, but in actual use of sensor 1a, reference electrode 22 is in contact with the second electrode 102a. Therefore, reference electrode 22 is electrically connected to the second electrode 102a. Thus, reference electrode 22 is electrically connected to reference electrode 23, reference electrode wirings 121a, 122a, and reference electrodes 24, 25. Consequently, reference electrode 22 is connected to a reference potential. Similar to the second electrode 102a, reference electrode 22 is, for example, a conductive adhesive with conductivity and adhesion. Therefore, reference electrode 22 also has conductivity in the Z-axis direction and stretchability in the X-axis direction. Furthermore, although not shown in the figure, electrodes are printed or deposited on the upper surface of the third stretchable substrate 21. Therefore, reference electrode 22 also ensures conductivity in the X-axis direction by being electrically connected to the electrodes formed on the upper surface of the third stretchable substrate 21.

[0060] An insulator 27 is disposed on the signal electrode wiring 120a. The insulator 27 covers approximately the entire surface of the signal electrode wiring 120a. As a result, the second electrode 102a is not electrically connected to the signal electrode wiring 120a.

[0061] The third telescopic substrate 21 is disposed on the fourth main surface SF4 side of the first telescopic substrate 11, separated from the reference electrode 22. When viewed along the Z-axis, the size of the third telescopic substrate 21 is approximately the same as the size of the reference electrode 22. The other structures of the third telescopic substrate 21 are the same as those of the second telescopic substrate 20, and therefore are omitted from the description.

[0062] In this variation, adhesive 13 is not disposed on the first telescopic substrate 11. In this variation, adhesive 13 is disposed on the third telescopic substrate 21. The other structures of adhesive 13 in sensor 1a are the same as those of adhesive 13 in sensor 1, and therefore description is omitted.

[0063] Furthermore, the other structures of sensor 1a are the same as those of sensor 1, so the description is omitted.

[0064] (Effect)

[0065] In sensor 1a, the piezoelectric film sensor 10a is located between the second electrode 102a, which is connected to the reference potential, and the reference electrode 22. Therefore, noise generated outside the sensor 1a is easily blocked by the second electrode 102a or the reference electrode 22. As a result, the piezoelectric film sensor 10a is less susceptible to noise.

[0066] In sensor 1a, stretchable substrates (first stretchable substrate 11, second stretchable substrate 20, and third stretchable substrate 21) with elasticity are respectively disposed on the positive and negative sides of the Z-axis of the piezoelectric membrane sensor 10a. This allows for a balance between the stress (first stress) applied to sensor 1a by the second stretchable substrate 20 at the positive Z-axis position of the piezoelectric membrane sensor 10a and the stress (second stress) applied to sensor 1a by the first and third stretchable substrates 21 at the negative Z-axis position of the piezoelectric membrane sensor 10a (the first and second stresses easily cancel each other out). Therefore, sensor 1a is less prone to warping.

[0067] In addition, sensor 1a has the same effect as sensor 1.

[0068] [Other effects of sensor 1a]

[0069] The second electrode 102a is attached to a second stretchable substrate 20 that is stretchable in the X-axis direction, and the reference electrode 22 is also attached to a third stretchable substrate 21 that is stretchable in the X-axis direction. Therefore, the fit between the second electrode 102a and the reference electrode 22, which function as shielding elements, and the piezoelectric film sensor 10a can be improved. As a result, the signal generated by the piezoelectric film sensor 10a will not affect external devices as noise.

[0070] For example, when mounting a piezoelectric film sensor 10a onto a printed circuit board, resin potting is sometimes used, but this can potentially cause cracks at the mounting boundary. Here, in sensor 1a, the piezoelectric film sensor 10a is covered by flexible second stretchable substrate 20 and first stretchable substrate 11. Therefore, even when mounting is done via potting, shrinking the second stretchable substrate 20 and first stretchable substrate 11 reduces the likelihood of large forces at the mounting boundary. Consequently, cracks are less likely to occur at the mounting boundary. As a result, the reliability of sensor 1a is easily improved.

[0071] A portion (the first portion) of the stretchable second substrate 20 and the third stretchable substrate 21 overlaps entirely with the piezoelectric membrane sensor 10a when viewed from above, while a portion other than the first portion (the second portion) does not overlap with the piezoelectric membrane sensor 10a. This makes it easier to reduce the hardness difference between the harder portion of the sensor 1a (e.g., the portion where the piezoelectric membrane sensor 10a is located) and the softer portion of the sensor 1a (e.g., the portion where the piezoelectric membrane sensor 10a is not located). Consequently, stress concentration is less likely to occur at the boundary between the harder and softer portions, thus reducing the likelihood of damage to the sensor 1a. As a result, the reliability of the sensor 1a is improved.

[0072] In sensor 1a, such as Figure 3As shown, reference electrode wirings 121a, 122a and reference electrode 23 surround the signal electrode wiring 120a. Therefore, the signal generated by the piezoelectric film sensor 10a will not affect external devices as noise.

[0073] [Variation Example 2]

[0074] Hereinafter, the sensor 1b of the modified example 2 of sensor 1 will be described with reference to the accompanying drawings. Figure 5 This is a top view of sensor 1b in variant example 2. Figure 6 yes Figure 5 The AA section view shown. Figure 5 In the middle, the following was omitted. Figure 6 The description of the second stretchable substrate 20, the stretchable substrate electrode 30, the second electrode 102a, and the second electrode 102b shown.

[0075] like Figure 5 and Figure 6 As shown, sensor 1b differs from sensor 1a in that: sensor 1b has a piezoelectric film sensor 10b, which is different from piezoelectric film sensor 10a; it also has a telescopic substrate electrode 30; and it has a telescopic electrode wiring 12b, which is different from telescopic electrode wiring 12a. Piezoelectric film sensor 10b also differs from piezoelectric film sensor 10a in that it includes a first electrode 100b and a second electrode 102b.

[0076] like Figure 6 As shown, the first electrode 100b is located between the piezoelectric film 101 and the first electrode 100. In this modified example 2, the first electrode 100b (sensor electrode) is directly formed on the main surface SF11 of the first film. The first electrode 100b is formed on the main surface SF11 of the first film through processes such as printing and vapor deposition. The first electrode 100b is formed on the entire surface of the main surface SF11 of the first film.

[0077] like Figure 6 As shown, the second electrode 102b is located between the piezoelectric film 101 and the second electrode 102a. In this modified example 2, similar to the first electrode 100b, the second electrode 102b (sensor electrode) is formed directly on the main surface SF12 of the second film. The other structures of the second electrode 102b are the same as those of the first electrode 100b, so the description is omitted.

[0078] like Figure 6 As shown, the telescopic substrate electrode 30 is located between the second electrode 102a and the second telescopic substrate 20. The telescopic substrate electrode 30 is formed directly on the second telescopic substrate 20. The telescopic substrate electrode 30 is fixed to the first main surface SF1a by being formed on the first main surface SF1a. The telescopic substrate electrode 30 is formed over approximately the entire surface of the first main surface SF1a. The telescopic substrate electrode 30 is telescopic in the X-axis direction.

[0079] The telescopic electrode wiring 12b differs from the telescopic electrode wiring 12a in that it is directly formed on the third main surface SF3. Therefore, the signal electrode wiring 120b, the reference electrode wiring 121b, and the reference electrode wiring 122b included in the telescopic electrode wiring 12b are each directly formed on the third main surface SF3.

[0080] (Effect)

[0081] In sensor 1b, the first electrode 100b is formed directly on the main surface of the first film SF11. Therefore, compared to the structure of Modified Example 1, the distance (inter-electrode distance) between the first electrode 100b and the second electrode 102b separated by the piezoelectric film 101 is shorter. Consequently, compared to the structure of Modified Example 1, the parasitic capacitance generated between the first electrode 100b and the second electrode 102b is smaller. Therefore, sensor 1b is less susceptible to the effects of this parasitic capacitance. As a result, the sensitivity of sensor 1b is improved compared to the structure of Modified Example 1. Similarly, since the second electrode 102b is formed directly on the main surface of the second film SF12, the sensitivity of sensor 1b is improved compared to the structure of Modified Example 1.

[0082] In addition, sensor 1b has the same effect as sensors 1 and 1a.

[0083] [Other effects of sensor 1b]

[0084] For example, in a sensor (hereinafter referred to as Comparative Example 2) where a conductive strip containing a core material such as copper foil is adhered to the second stretchable substrate instead of the electrode being directly formed on the second stretchable substrate, the second stretchable substrate can be adhered to the piezoelectric film sensor without reducing the conductivity of Comparative Example 2. However, for sensors containing a core material such as copper foil, the elastic modulus is higher than that of the aforementioned conductive adhesive. Therefore, strong rebound is likely to occur in Comparative Example 2, and Comparative Example 2 may peel off from the test object.

[0085] On the other hand, in sensor 1b, the stretchable substrate electrode 30 is directly formed on the second stretchable substrate 20, and the second stretchable substrate 20 is adhered to the piezoelectric film sensor 10b using a stretchable conductive adhesive that does not contain a core material, namely the second electrode 102a. Therefore, the second stretchable substrate 20 can be adhered to the piezoelectric film sensor 10b without reducing the conductivity of sensor 1b, and the elastic modulus of sensor 1b is less than that of Comparative Example 2. Therefore, sensor 1b can be made less prone to peeling from the object OB being measured without reducing the conductivity of sensor 1b.

[0086] [Variation Example 3]

[0087] Hereinafter, the sensor 1c of the modified example 3 of the sensor 1 will be described with reference to the accompanying drawings. Figure 7 This is a top view of sensor 1c in variant example 3. Figure 8 yes Figure 7 The AA section view shown. Figure 7 In the middle, the following was omitted. Figure 8 The description of the second stretchable substrate 20 and the second electrode 102a shown.

[0088] like Figure 7 and Figure 8 As shown, the difference between sensor 1c and sensor 1a is that sensor 1c also includes a mounting member 40 and a mounting member electrode 400, which serves as a signal electrode and is electrically connected to the mounting member 40. The mounting member 40 and the mounting member electrode 400 are respectively disposed on the third main surface SF3 of the first stretchable substrate 11. The mounting member 40 is disposed on the mounting member electrode 400. The mounting member 40 is a thermistor or an accelerometer, etc. By including the mounting member 40, sensor 1c becomes a flexible sensor, for example, capable of detecting strain, temperature, or acceleration. In this case, in addition to the piezoelectric film sensor 10, the mounting member 40 can also be mounted on a flexible measurement object OB or a curved surface of the measurement object OB. Thus, the ease of use of sensor 1c as a flexible sensor is improved. The other structures of sensor 1c are the same as those of sensor 1a, so descriptions are omitted. Furthermore, although not shown, approximately the entire surface of the mounting member electrode 400 is covered by an insulator similar to the insulator 27.

[0089] [Variation Example 4]

[0090] Hereinafter, the sensor 1d of the modified example 4 of the sensor 1 will be described with reference to the accompanying drawings. Figure 9 This is an exploded stereoscopic view of sensor 1d in variation example 4.

[0091] like Figure 9 As shown, sensor 1d differs from sensor 1 in that it includes a piezoelectric film sensor 10d, which is different from piezoelectric film sensor 10; it includes a telescopic electrode wiring 12d, which is different from telescopic electrode wiring 12; it includes an adhesive 13d, which is different from adhesive 13; and it also includes a second telescopic substrate 20 and an insulator 27. The piezoelectric film sensor 10d differs from the piezoelectric film sensor 10 in that it includes a second electrode 102d, which is different from the second electrode 102. The telescopic electrode wiring 12d differs from the telescopic electrode wiring 12 in that it includes a signal electrode wiring 120d and a reference electrode wiring 121d. Furthermore, the second electrode 102d, the telescopic electrode wiring 12d, and the adhesive 13d will be described with reference to the points where they differ from the second electrode 102, the telescopic electrode wiring 12, and the adhesive 13. Similarly, the second telescopic substrate 20 and the insulator 27 will be described with reference to the points where they differ from the second telescopic substrate 20 and the insulator 27 of sensor 1a.

[0092] The entire surface of the first membrane main surface SF11 is covered by the first electrode 100. Furthermore, the entire surface of the second membrane main surface SF12 is covered by the second electrode 102d.

[0093] When viewed along the Z-axis, the second electrode 102d has a shape formed by two rectangles (hereinafter referred to as the first rectangle R1 and the second rectangle R2) arranged in the X-axis direction. The second electrode 102d is, for example, a conductive adhesive that provides conductivity in the Z-axis direction by means of an adhesive film comprising a conductive mesh fabric and an opening in the conductive mesh fabric. Thus, the second electrode 102a has conductivity in the Z-axis direction and high elasticity. The second electrode 102d has a region OA1 that overlaps with the main surface SF12 of the second film when viewed along the Z-axis.

[0094] When viewed along the Z-axis, the second telescopic substrate 20 has a shape formed by two rectangles arranged in the X-axis direction. Similarly, in sensor 1d, the entire surface of the first main surface SF1a of the second telescopic substrate 20 is covered by the second electrode 102d.

[0095] When viewed along the Z-axis, the first stretchable substrate 11 has a shape formed by two rectangles (hereinafter referred to as the third rectangle R3 and the fourth rectangle R4) arranged in the X-axis direction. The length L4 of the fourth rectangle R4 in the Y-axis direction is shorter than the length L2 of the second rectangle R2 in the Y-axis direction. Furthermore, the third rectangle R3 has a region NOA at its end in the positive X-axis direction that does not overlap with the piezoelectric film 101 or the first electrode 100 when viewed along the Z-axis direction. Alternatively, the length L4 of the fourth rectangle R4 in the Y-axis direction may not be shorter than the length L2 of the second rectangle R2 in the Y-axis direction. Also, the third rectangle R3 may not have a region NOA at its end in the positive X-axis direction that does not overlap with the piezoelectric film 101 or the first electrode 100 when viewed along the Z-axis direction.

[0096] Signal electrode wiring 120d is formed on the third main surface SF3 of the first stretchable substrate 11. Signal electrode wiring 120d has a third portion P3 located within the region OA2 overlapping with the first electrode 100 when viewed along the Z-axis, and a fourth portion P4 extending from the third portion P3 in the positive X-axis direction. The third portion P3 covers approximately the entire surface of the first electrode 100 located on the negative side of the Z-axis. Thus, signal electrode wiring 120d is electrically connected to the first electrode 100. Signal electrode wiring 120d is stretchable in the X-axis direction.

[0097] A reference electrode wiring 121d is formed on the third main surface SF3 of the first stretchable substrate 11. More specifically, the reference electrode wiring 121d is formed at the end of the third main surface SF3 of the first stretchable substrate 11 in the positive X-axis direction. The reference electrode wiring 121d and the fourth portion P4 are arranged sequentially along the negative Y-axis at the end of the third main surface SF3 of the first stretchable substrate 11 in the positive X-axis direction. When viewed along the Z-axis direction, the reference electrode wiring 121d does not overlap with the piezoelectric film 101 or the first electrode 100. On the other hand, when viewed along the Z-axis direction, the reference electrode wiring 121d overlaps with the second electrode 102d. Therefore, the reference electrode wiring 121d is electrically connected to the second electrode 102d. By connecting the reference electrode wiring 121d to a reference potential, the second electrode 102d is also connected to a reference potential.

[0098] The materials for the signal electrode wiring 120d and the reference electrode wiring 121d are, for example, carbon. By using carbon instead of metal for the signal electrode wiring 120d and the reference electrode wiring 121d, ion migration can be suppressed.

[0099] An insulator 27 is disposed on the fourth portion P4 of the signal electrode wiring 120d. The insulator 27 covers the entire surface of the fourth portion P4. Thus, the signal electrode wiring 120d is not electrically connected to the second electrode 102d.

[0100] When viewed along the Z-axis, the adhesive 13d has a shape formed by two rectangles arranged in the X-axis direction. The adhesive 13d is disposed on the fourth main surface SF4 of the first stretchable substrate 11. The adhesive 13d covers the entire surface of the fourth main surface SF4. The adhesive 13d fixes the second stretchable substrate 20, the piezoelectric film sensor 10d, the stretchable electrode wiring 12d, and the first stretchable substrate 11 to the object being measured, OB. The adhesive 13d is, for example, a conductive double-sided tape. Such an adhesive 13d is, for example, a conductive adhesive that has conductivity in the Z-axis direction by comprising a conductive mesh fabric and an adhesive film disposed at the openings of the conductive mesh fabric. Thus, the adhesive 13d has conductivity in the Z-axis direction and high stretchability. The adhesive 13d is connected to a reference potential. For example, the conductive mesh fabric is connected to a reference potential.

[0101] As described above, the second electrode 102d and the adhesive 13d each comprise a conductive mesh fabric and an adhesive film disposed at an opening in the conductive mesh fabric, thereby giving the second electrode 102d and the adhesive 13d high elasticity. This improves the elasticity of the sensor 1d.

[0102] Similar to sensor 1a, in sensor 1d, the piezoelectric film sensor 10d is located between the second electrode 102d, which is connected to the reference potential, and the adhesive 13d. Therefore, noise generated outside the sensor 1d is easily blocked by the second electrode 102d or the adhesive 13d. As a result, the piezoelectric film sensor 10d is less susceptible to this noise.

[0103] Furthermore, the sensor 1d may also include an adhesive 13 disposed on the negative side of the adhesive 13d along the Z-axis. The adhesive 13 fixes the second stretchable substrate 20, the piezoelectric film sensor 10d, the stretchable electrode wiring 12d, the first stretchable substrate 11, and the adhesive 13d to the object being measured, OB. The adhesive 13 may be, for example, a double-sided tape such as OCA (Optically Clear Adhesive). In this case, the adhesive 13d may also be, for example, a single-sided tape with conductivity.

[0104] [Variation Example 5]

[0105] Hereinafter, the sensor 1e of the modified example 5 of the sensor 1 will be described with reference to the accompanying drawings. Figure 10 This is an exploded perspective view of sensor 1e in variant example 5.

[0106] Sensor 1e differs from sensor 1d in that the first electrode 100, piezoelectric film 101, and first stretchable substrate 11 move in the positive direction of the X-axis.

[0107] By moving the first electrode 100, piezoelectric film 101, and first stretchable substrate 11 in the positive X-axis direction, the second electrode 102d has a region OA3 at its end in the negative X-axis direction that overlaps with the adhesive 13d but not with the first electrode 100, piezoelectric film 101, and first stretchable substrate 11. Similarly, the adhesive 13d has a region OA4 at its end in the negative X-axis direction that overlaps with the second electrode 102d but not with the first electrode 100, piezoelectric film 101, and first stretchable substrate 11. Therefore, the second electrode 102d and the adhesive 13d are in direct contact at their ends in the negative X-axis direction. Thus, the second electrode 102d and the adhesive 13d are directly electrically connected.

[0108] As described above, the second electrode 102a and the adhesive 13d are conductive adhesives that have conductivity in the Z-axis direction, respectively, by means of an adhesive film comprising a conductive mesh fabric and an opening in the conductive mesh fabric. The contact between these conductive adhesives ensures electrical connection between the second electrode 102a and the adhesive 13d, thereby achieving both electrical connection between the second electrode 102a and the adhesive 13d and high flexibility in the X-axis direction.

[0109] By moving the first electrode 100, the piezoelectric film 101, and the first stretchable substrate 11 in the positive X-axis direction, the second electrode 102d is made to have a region OA5 that overlaps with the first stretchable substrate 11 but not with the first electrode 100 and the piezoelectric film 101. Similarly, the first stretchable substrate 11 has a region OA6 that overlaps with the second electrode 102d but not with the first electrode 100 and the piezoelectric film 101. Therefore, the second electrode 102d is in direct contact with the first stretchable substrate 11.

[0110] By making the second electrode 102d directly contact the first telescopic substrate 11, the second electrode 102d covers the area around the signal electrode wiring 120d. This shields the signal electrode wiring 120d from noise originating from a direction orthogonal to the Z-axis. Furthermore, the second electrode 102d and the first telescopic substrate 11 can be punched to the same dimensions, allowing for simultaneous punching of both during the manufacturing process of the sensor 1e, thus improving the processing convenience of the sensor 1e.

[0111] [Other Implementation Methods]

[0112] The description of this embodiment is illustrative in all respects and should not be considered limiting. The scope of the invention is set forth not by the embodiments described above, but by the claims. Furthermore, the scope of the invention includes the scope equivalent to the claims.

[0113] Furthermore, the sensors of the present invention are not limited to sensors 1, 1a to 1e, and can be modified within the scope of their essence. The structures of sensors 1, 1a to 1e can also be combined arbitrarily.

[0114] Furthermore, the X-axis, Y-axis, and Z-axis directions are defined for illustrative purposes. Therefore, the X-axis, Y-axis, and Z-axis directions used in actual applications of sensors 1, 1a to 1e do not necessarily need to be consistent with the X-axis, Y-axis, and Z-axis directions in each embodiment and variation.

[0115] Furthermore, in sensor 1b, it is sufficient that the first electrode 100b is directly formed on the first membrane main surface SF11 or the second electrode 102b is directly formed on the second membrane main surface SF12.

[0116] Furthermore, similar to the first electrode 100b, the reference electrodes 23, 24, 25 and signal electrodes 26 in the sensor 1b can also be directly formed on the third main surface SF3.

[0117] Alternatively, the telescopic electrode wiring 12 may be made of a conductive material such as copper foil and fixed to the third main surface SF3 with the aid of double-sided tape.

[0118] Furthermore, when the adhesive 13 is a double-sided tape, it is preferable that the adhesive 13 does not contain a core material such as a film. This is because when the adhesive 13 contains a core material such as a film, its elastic modulus is higher than when it does not contain a core material. As a result, the sensor 1 is more prone to strong rebound, increasing the likelihood that the sensor 1 will peel off from the object being measured, OB.

[0119] The present invention has the following structure.

[0120] (1) A sensor comprising: a piezoelectric film sensor having a first main surface and a second main surface opposite to the first main surface; a first stretchable substrate having stretchability in a first direction parallel to the first main surface, having a third main surface and a fourth main surface opposite to the third main surface and in contact with the piezoelectric film sensor; a stretchable electrode wiring having stretchability in the first direction, disposed on the third main surface and in contact with the first main surface; and an adhesive disposed on the fourth main surface.

[0121] The thickness of the piezoelectric film sensor is thinner than the combined thickness of the telescopic electrode wiring, the thickness of the first telescopic substrate, and the thickness of the adhesive.

[0122] (2) According to the sensor described in (1), wherein the elastic modulus of the first stretchable substrate is less than 1000 MPa.

[0123] (3) According to the sensor described in (2), wherein the material of the first stretchable substrate is an elastic system membrane.

[0124] (4) The sensor according to any one of (1) to (3), wherein the sensor further comprises a second telescopic substrate having telescopic properties in the first direction and being adhered to the second main surface.

[0125] (5) The sensor according to (4) further comprises a stretchable substrate electrode, which is directly formed on the second stretchable substrate and has stretchability in the first direction.

[0126] (6) The sensor according to (4) or (5), wherein the elastic modulus of the second stretchable substrate is less than 1000 MPa.

[0127] (7) The sensor according to any one of (1) to (6), wherein the telescopic electrode wiring is directly formed on the third main surface.

[0128] (8) The sensor according to (7), wherein the telescopic electrode wiring includes signal electrode wiring and reference electrode wiring.

[0129] (9) The sensor according to any one of (1) to (8), wherein the piezoelectric film sensor comprises: a piezoelectric film having a first film main surface and a second film main surface; and a sensor electrode formed directly on at least one of the first film main surface and the second film main surface.

[0130] (10) The sensor according to any one of (1) to (9), wherein the sensor further comprises a mounting component disposed on the third main surface.

[0131] Explanation of reference numerals in the attached figures

[0132] 1. 1a~1e, Sensor; 10. 10a, 10b, 10d, Piezoelectric film sensor; 11. First telescopic substrate; 12. 12a, 12b, 12d, Telescopic electrode wiring; 13. 13d, Adhesive; 20. Second telescopic substrate; 21. Third telescopic substrate; 22. 23. 24. 25. Reference electrode; 26. Signal electrode; 27. Insulator; 30. Telescopic substrate electrode; 40. Mounting component; 100. 100b, First electrode; 101. Piezoelectric film; 102. 102a, 102b, 102d, Second electrode; 120a, 120b, 120d, Signal electrode Wiring; 121a, 121b, 121d, 122a, 122b, reference electrode wiring; 400, mounting component electrode; DS1, thickness; DS2, total value; NOA, OA1~OA6, area; OB, object to be measured; OD, orientation direction; P3, part 3; P4, part 4; R1, first rectangle; R2, second rectangle; R3, third rectangle; R4, fourth rectangle; SF1, SF1a, first main surface; SF2, SF2a, second main surface; SF3, third main surface; SF4, fourth main surface; SF11, first membrane main surface; SF12, second membrane main surface.

Claims

1. A sensor, wherein the sensor comprises: a piezoelectric film sensor having a first main surface and a second main surface opposite to the first main surface; a first stretchable substrate having stretchability in a first direction parallel to the first main surface, having a third main surface and a fourth main surface opposite to the third main surface, and being in contact with the piezoelectric film sensor; a stretchable electrode wiring having stretchability in the first direction, being disposed on the third main surface, and being in contact with the first main surface; and an adhesive disposed on the fourth main surface, a thickness of the piezoelectric film sensor is thinner than a total value of a thickness of the stretchable electrode wiring, a thickness of the first stretchable substrate, and a thickness of the adhesive.

2. The sensor according to claim 1, wherein an elastic modulus of the first stretchable substrate is 1000 MPa or less.

3. The sensor according to claim 2, wherein a material of the first stretchable substrate is an elastic system film.

4. The sensor according to any one of claims 1 to 3, wherein the sensor further comprises a second stretchable substrate having stretchability in the first direction and being attached to the second main surface.

5. The sensor according to claim 4, wherein the sensor further comprises a stretchable substrate electrode directly formed on the second stretchable substrate and having stretchability in the first direction.

6. The sensor according to claim 4 or 5, wherein an elastic modulus of the second stretchable substrate is 1000 MPa or less.

7. The sensor according to any one of claims 1 to 6, wherein the stretchable electrode wiring is directly formed on the third main surface.

8. The sensor according to claim 7, wherein the stretchable electrode wiring includes a signal electrode wiring and a reference electrode wiring.

9. The sensor according to any one of claims 1 to 8, wherein the piezoelectric film sensor comprises: a piezoelectric film having a first film main surface and a second film main surface; and a sensor electrode directly formed on at least one of the first film main surface and the second film main surface.

10. The sensor according to any one of claims 1 to 9, wherein the sensor further comprises a mounting member disposed on the third main surface.

11. The sensor according to claim 8, wherein materials of the signal electrode wiring and the reference electrode wiring are carbon, respectively.

12. The sensor according to any one of claims 1 to 11, wherein the piezoelectric film sensor comprises: a piezoelectric film having a first film main surface and a second film main surface; and a sensor electrode fixed to the second film main surface, having a main surface corresponding to the second main surface, the sensor electrode and the adhesive include a conductive mesh fabric and an adhesive film provided to an opening portion of the conductive mesh fabric, respectively.

13. The sensor according to claim 12, wherein the sensor electrode is in direct contact with the first stretchable substrate.

14. The sensor according to claim 12 or 13, wherein the sensor electrode is in direct contact with the adhesive. ​

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