Bending sensor and electronic apparatus
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- MURATA MFG CO LTD
- Filing Date
- 2025-12-24
- Publication Date
- 2026-07-30
Smart Images
Figure JP2025045243_30072026_PF_FP_ABST
Abstract
Description
Bending Sensor and Electronic Device
[0001] The present invention relates to a bending sensor and an electronic device.
[0002] As a conventional invention related to a bending sensor, for example, the bending sensor described in Patent Document 1 is known. The bending sensor described in Patent Document 1 includes a piezoelectric film and an adhesive. The adhesive is disposed on the main surface of the piezoelectric film and attaches the piezoelectric film to a bendable substrate. At least a bending portion that is bent together with the substrate among the end faces of the piezoelectric film is covered with the adhesive.
[0003] International Publication No. 2023 / 276955
[0004] When bent, stress concentrates at the bending portion. In the bending sensor described in Patent Document 1, since the piezoelectric film is mounted at the bending portion, a mechanical load is applied to the piezoelectric film during bending. Therefore, the piezoelectric film may break and the sensitivity of the piezoelectric film may decrease.
[0005] Therefore, an object of the present invention is to provide a bending sensor and an electronic device that can suppress a mechanical load from being applied to a piezoelectric element during bending.
[0006] A bending sensor according to one embodiment of the present invention is a bending sensor attached to an adherend that is bendable and has a bending portion that bends when bent and a first region adjacent to the bending portion, the bending sensor having: a substrate having flexibility and a main surface; a piezoelectric element having a main surface; and a first adhesive that fixes the main surface of the piezoelectric element to the main surface of the substrate, wherein the main surface of the substrate is attached to the adherend, the substrate straddles the bending portion and the first region, and the piezoelectric element is located in the first region and not in the bending portion.
[0007] An electronic device according to one embodiment of the present invention comprises: a bendable adherend; a first bending sensor attached to the adherend; and a second bending sensor attached to the adherend, wherein the adherend has a first bending portion that bends when bent, and a second bending portion that bends when bent and is different from the first bending portion, and each of the first bending sensor and the second bending sensor is flexible and comprises: a substrate having a main surface attached to the adherend; a piezoelectric element having a main surface; and a first adhesive for fixing the main surface of the piezoelectric element to the main surface of the substrate, wherein the length of the substrate in the longitudinal direction of the adherend is 1.2 times or more the length of the piezoelectric element in the longitudinal direction, the substrate of the first bending sensor is located across the first bending portion and a first region adjacent to the first bending portion, and the piezoelectric element of the first bending sensor is located in the first region and not in the first bending portion or the second bending portion. The substrate of the second bending sensor is positioned across the second bending portion and a second region adjacent to the second bending portion, and the piezoelectric element of the second bending sensor is located in the second region and not in the first bending portion or the second bending portion.
[0008] In a bending sensor and electronic device according to one embodiment of the present invention, the piezoelectric element is not located at the bending portion where stress is concentrated during bending, and mechanical load is less likely to be applied to the piezoelectric element during bending. Therefore, according to the present invention, it is possible to suppress the application of mechanical load to the piezoelectric element during bending.
[0009] Figure 1A is a perspective view of the electronic device 100, and Figure 1B is a perspective view of the electronic device 100 in a folded state. Figure 2 is a cross-sectional view of the electronic device 100 taken along the line A-A shown in Figure 1A. Figure 3 is a cross-sectional view of the electronic device 100 showing an enlarged portion of the first region A1. Figure 4 is an exploded perspective view of the piezoelectric element 14. Figure 5 is a plan view of the electronic device 100. Figure 6 is a side view showing the electronic device 100 in a folded state. Figure 7 is a plan view of the electronic device 100a. Figure 8 is a plan view of the electronic device 100b. Figure 9 is a perspective view of the electronic device 100c. Figure 10 is a plan view of the electronic device 100c. Figure 11 is a plan view of the electronic device 100d. Figure 12 is a plan view of the electronic device 100e. Figure 13 is a plan view of the electronic device 100f. Figure 14 is a plan view of the electronic device 100g. Figure 15 is a plan view of the electronic device 100h. Figure 16 is a cross-sectional view of the electronic device 100i cut along the line A-A shown in Figure 1A. Figure 17 is a plan view of the electronic device 100i. Figure 18 is a side view showing the electronic device 100i in a folded state. Figure 19 is a side view of the electronic device 100j. Figure 20 is a plan view of the electronic device 100j. Figure 21 is a plan view of the electronic device 100j with a changed arrangement of piezoelectric elements 14. Figure 22 is a side view of the electronic device 100j with a changed arrangement of piezoelectric elements 14. Figure 23 is a side view of the electronic device 100j with a changed arrangement of piezoelectric elements 14. Figure 24 is a side view of the electronic device 100j with a changed arrangement of piezoelectric elements 14. Figure 25 is a side view of the electronic device 100j with a changed arrangement of piezoelectric elements 14. Figure 26 is a side view of the electronic device 100k. Figure 27 is a side view of the electronic device 100k with a changed arrangement of piezoelectric elements 14. Figure 28 is a side view of electronic device 100k with a modified arrangement of piezoelectric elements 14. Figure 29 is a side view of electronic device 100i with the arrangement of adhesive 13 similar to that of adhesive 13 related to any of the bending sensors 1e to 1h. Figure 30 is a side view of electronic device 100i with the arrangement of adhesive 15 in a plan view similar to that of adhesive 13 related to any of the bending sensors 1e to 1h.
[0010] [First Embodiment] Below, a bending sensor 1 and an electronic device 100 equipped with the bending sensor 1 according to the first embodiment of the present invention will be described with reference to the drawings. Note that in each figure, wiring and the like have been omitted for the sake of clarity.
[0011] Figure 1A is a perspective view of the electronic device 100, and Figure 1B is a perspective view of the electronic device 100 in a folded state. The electronic device 100 is, for example, an information processing device such as a smartphone.
[0012] As shown in Figure 1A, the electronic device 100 comprises a housing 101 and a surface panel 102. Hereinafter, the width direction (horizontal direction) of the housing 101 will be referred to as the X direction, the length direction (vertical direction) as the Y direction, and the thickness direction as the Z direction.
[0013] The housing 101 is roughly rectangular in shape. The top surface (end face in the Z direction) of the housing 101 is open. The surface panel 102 is flat. When viewed in the Z direction, the surface panel 102 is rectangular in shape, with a short side extending in the X direction and a long side extending in the Y direction. The surface panel 102 is supported by the housing 101 so as to close the opening of the housing 101. The surface panel 102 functions as an operating surface on which the user performs touch operations using their finger or a pen.
[0014] Figure 2 is a cross-sectional view of the electronic device 100 taken along the line A-A shown in Figure 1A. As shown in Figure 2, the electronic device 100 is equipped with a bending sensor 1 inside the housing 101. The bending sensor 1 is attached to the surface panel 102 that faces the inside of the housing 101. The bending sensor 1 comprises an adhesive 11, a base material 12, an adhesive 13, and a piezoelectric element 14.
[0015] In this embodiment, the bending sensor 1 is attached to the surface panel 102, but the bending sensor 1 may be attached to a display, touch panel, or housing, etc. If the bending sensor 1 is transparent, the display, bending sensor 1, and surface panel 102 may be arranged in this order along the Z direction.
[0016] The housing 101, surface panel 102, and base material 12 are flexible. This allows the electronic device 100 to be bent. For example, as shown in Figure 1B, the electronic device 100 can be bent to define a predetermined range with a bending line L parallel to the X direction as the center line, which is the bending point BEP. In this embodiment, the device is bent with the surface panel 102 facing inward, but it may also be bent with the surface panel 102 facing outward.
[0017] When the electronic device 100 is bent, the surface panel 102 is bent in the same way. Therefore, the surface panel 102 is bendable. For example, the surface panel 102 is bent along a fold line L. As shown in Figure 2, the surface panel 102 has a bent portion BP that bends with the fold line L as the center line when bent, and a first region A1 adjacent to the bent portion BP. The bent portion BP and the first region A1 are arranged in this order along the Y direction perpendicular to the fold line L. The first region A1 is adjacent to the bent portion BP along the Y direction perpendicular to the fold line L. The Y direction corresponds to the first direction according to the present invention.
[0018] The surface panel 102 (electronic device 100) can be opened and closed from 0 degrees to 180 degrees. The bending sensor 1 detects whether the surface panel 102 (electronic device 100) is bent and the state of the bend (current opening / closing angle). The surface panel 102 (electronic device 100) may be made bendable by providing a hinge or bellows structure, etc., at the bending portion BP.
[0019] As shown in Figure 2, the base material 12 is flat. The base material 12 is rectangular in shape, with a short side extending in the X direction and a long side extending in the Y direction when viewed in the Z direction. The material of the base material 12 is, for example, PET (Polyethylene Terephthalate). However, the material of the base material 12 is not limited to PET; the base material 12 may be, for example, a shim plate. The main surface MS11 of the base material 12 is attached to the surface panel 102 that faces the inside of the housing 101. In this embodiment, the surface panel 102 that faces the inside of the housing 101 is flat, but it may be curved. The surface panel 102 corresponds to the adherend according to the present invention.
[0020] The main surface MS11 of the substrate 12 includes opposing first main surface MS1 and second main surface MS2. The first main surface MS1 is located in the Z direction relative to the second main surface MS2. The first main surface MS1 is attached to the surface panel 102 by an adhesive 11 that covers the entire first main surface MS1. The adhesive 11 is, for example, a double-sided tape such as OCA (Optically Clear Adhesive). Note that the adhesive 11 does not necessarily have to cover the entire first main surface MS1. Also, the adhesive 11 is not limited to OCA. Furthermore, the thickness of the adhesive 11 in the Z direction is arbitrary.
[0021] Furthermore, the base material 12 does not have to be rectangular when viewed in the Z direction. Also, the adhesive 11 may cover only a part of the first main surface MS1. Moreover, in this invention, the adhesive 11 is not an essential component.
[0022] In this embodiment, the piezoelectric element 14, when viewed in the Z direction, overlaps with the central part of the second main surface MS2 of the substrate 12 in the X direction. The piezoelectric element 14 is flat. When viewed in the Z direction, the piezoelectric element 14 is rectangular in shape, having a long side extending in the X direction and a short side extending in the Y direction. The main surface MS14 of the piezoelectric element 14 is attached to the second main surface MS2 of the substrate 12. More specifically, the main surface MS14 includes opposing third main surface MS3 and fourth main surface MS4. The third main surface MS3 is located in the Z direction relative to the fourth main surface MS4. The third main surface MS3 is fixed to the second main surface MS2 by an adhesive 13 that covers the entire third main surface MS3. The adhesive 13 is, for example, a double-sided tape such as OCA. Note that the piezoelectric element 14 does not have to be rectangular when viewed in the Z direction. Also, the adhesive 13 does not have to cover the entire third main surface MS3. Furthermore, the adhesive 13 is not limited to OCA. The adhesive 13 corresponds to the first adhesive according to the present invention.
[0023] Furthermore, the piezoelectric element 14 does not necessarily have to overlap with the central part in the X direction of the second main surface MS2 of the substrate 12 when viewed in the Z direction.
[0024] Figure 3 is a cross-sectional view of the electronic device 100, showing an enlarged portion of the first region A1. As shown in Figure 3, the piezoelectric element 14 includes a piezoelectric film 141, a reference electrode 142, a signal electrode 143, an FPC 144, and a shielding member 145.
[0025] Figure 4 is an exploded perspective view of the piezoelectric element 14. As shown in Figure 4, the piezoelectric film 141 has a fifth main surface MS5 and a sixth main surface MS6 aligned along the Z direction. The fifth main surface MS5 is located in the Z direction relative to the sixth main surface MS6. When viewed in the Z direction, the piezoelectric film 141 has a rectangular shape with a long side extending in the X direction and a short side extending in the Y direction.
[0026] The piezoelectric film 141 is polarized by deformation, generating a voltage between the fifth main surface MS5 and the sixth main surface MS6. The voltage generated between the fifth main surface MS5 and the sixth main surface MS6 depends on the amount of deformation of the piezoelectric film 141.
[0027] The piezoelectric film 141 contains a piezoelectric material. The piezoelectric material is, for example, a chiral polymer. The chiral polymer is, for example, polylactic acid (PLA) such as L-type polylactic acid (PLLA) and D-type polylactic acid (PDLA). The main chain of PLA has a helical structure. PLA has piezoelectric properties when its molecules are oriented by uniaxial stretching. The piezoelectric film 141 has a piezoelectric constant of d14. Note that the piezoelectric material is not limited to a chiral polymer.
[0028] The PLA is stretched in the stretching direction OD. The stretching direction OD of the PLA forms a 45-degree angle with respect to both the X and Y directions. Note that 45 degrees may be within a range of approximately 45 degrees ± 10 degrees. The piezoelectric film 141 generates a voltage between the fifth main surface MS5 and the sixth main surface MS6 when stretched or compressed along the Y direction.
[0029] The reference electrode 142 is conductive. The material of the reference electrode 142 is, for example, copper. The reference electrode 142 is provided on the sixth main surface MS6 of the piezoelectric film 141. The reference electrode 142 covers the entire sixth main surface MS6. By being connected to the ground potential, the reference electrode 142 functions as a reference electrode and a shielding conductor. Note that the reference electrode 142 does not necessarily have to cover the entire sixth main surface MS6.
[0030] The signal electrode 143 is conductive. The material of the signal electrode 143 is, for example, copper. The signal electrode 143 is provided on the fifth main surface MS5 of the piezoelectric film 141. The signal electrode 143 covers the entire fifth main surface MS5. The signal electrode 143 functions as a signal electrode for outputting the voltage generated by the piezoelectric film 141 as an output signal. Note that the signal electrode 143 does not necessarily have to cover the entire fifth main surface MS5.
[0031] FPC 144 is insulating. The material of FPC 144 is, for example, polyimide. FPC 144 has a seventh main surface MS7 and an eighth main surface MS8 aligned along the Z direction. The seventh main surface MS7 is located in the Z direction relative to the eighth main surface MS8. When viewed in the Z direction, FPC 144 is rectangular in shape, with a long side extending in the X direction and a short side extending in the Y direction. A wiring layer (not shown) is formed on the eighth main surface MS8. The signal electrode 143 is connected to the wiring of the wiring layer.
[0032] The shielding member 145 is conductive. The material of the shielding member 145 is, for example, copper. The shielding member 145 is provided on the seventh main surface MS7. The shielding member 145 covers the entire seventh main surface MS7. By being connected to the ground potential, the shielding member 145 functions as a reference electrode and a shielding conductor. Note that the shielding member 145 does not necessarily have to cover the entire seventh main surface MS7.
[0033] The reference electrode 142 and the signal electrode 143 are connected to a voltage detection circuit (not shown). The voltage detection circuit detects the voltage generated by the piezoelectric film 141. The voltage detection circuit is connected to a calculation circuit (not shown). The calculation circuit detects the bending of the surface panel 102 when the voltage exceeds a predetermined value. The calculation circuit can also detect the bending state of the surface panel 102 (current opening / closing angle) by performing calculations such as integration on the voltage.
[0034] Figure 5 is a plan view of the electronic device 100. As shown in Figure 5, when viewed in the Z direction, the first region A1 encloses the bent portion BP. When viewed in the Z direction, the bent portion BP substantially coincides with the fold point BEP shown in Figure 1. Here, in Figure 5, the first region A1 located to the left of the bent portion BP is designated as the first region A11, and the first region A1 located to the right of the bent portion BP is designated as the first region A12. The bent portion BP has a first bent region BA1 located between the first region A11 and the fold line L, and a second bent region BA2 located between the fold line L and the first region A12. Viewing in the Z direction corresponds to the plan view according to the present invention.
[0035] The base material 12 is positioned across the first region A11, the bent portion BP, and the first region A12. That is, the base material 12 is positioned across the bent portion BP and the first region A1. The piezoelectric element 14 is located in the first region A11. That is, the piezoelectric element 14 is located in the first region A1 and not in the bent portion BP.
[0036] Figure 6 is a side view showing the electronic device 100 in a folded state. Note that in Figure 6, the housing 101 and adhesive 11 are omitted for the sake of clarity. As shown in Figure 6, when the electronic device 100 is not folded, both the base material 12 and the piezoelectric element 14 are at their natural length, and the piezoelectric film 141 does not generate voltage.
[0037] When the electronic device 100 is bent, the base material 12 is stretched and compressed at the bent portion BP. More specifically, at the bent portion BP, the first main surface MS1 of the base material 12 is compressed toward the bending line L. On the other hand, at the bent portion BP, the second main surface MS2 of the base material 12 is stretched. Specifically, in the first bending region BA1, the second main surface MS2 stretches toward the first region A11. In the second bending region BA2, the second main surface MS2 stretches toward the first region A12. Consequently, in the first region A11, the base material 12 stretches toward the first bending region BA1. Also, in the first region A12, the base material 12 stretches toward the second bending region BA2. At this time, the piezoelectric element 14 provided in the first region A11 stretches toward the first bending region BA1. Therefore, the piezoelectric film 141 stretches along the Y direction. As a result, the piezoelectric film 141 generates a voltage.
[0038] In this embodiment, an example is shown in which the short sides of the surface panel 102 overlap when the electronic device 100 is folded along the folding line L. Therefore, in this embodiment, when the short sides of the surface panel 102 overlap, the bent portion BP is the bent part, and the first region A1 is a portion that does not bend and faces each other parallel to each other. Note that the folding line L is not limited to the example shown in this embodiment. For example, the entire surface panel 102 may be foldable.
[0039] The bending sensor 1 can suppress the mechanical load applied to the piezoelectric element 14 during bending. More specifically, the piezoelectric element 14 is located in the first region A1 and not in the bending portion BP. Stress concentrates in the bending portion BP during bending. Because the piezoelectric element 14 is not located in the bending portion BP, the piezoelectric film 141 is less likely to be subjected to mechanical load during bending. As a result, the bending sensor 1 can suppress the mechanical load applied to the piezoelectric element 14 during bending.
[0040] Further, according to the bending sensor 1, the base material 12 is located across the first region A11, the bending portion BP, and the first region A12. Therefore, according to the bending sensor 1, the presence or absence of bending and the bending state (current opening / closing angle) of the surface panel 102 (electronic device 100) can be accurately detected as compared with the case where the base material 12 is located only in the first region A11.
[0041] [First Modified Example] Hereinafter, the bending sensor 1a according to the first modified example of the present invention and the electronic device 100a including the bending sensor 1a will be described with reference to the drawings. FIG. 7 is a plan view of the electronic device 100a. Note that only the portions different from the bending sensor 1 and the electronic device 100 will be described for the bending sensor 1a and the electronic device 100a, respectively, and the description thereof will be omitted later.
[0042] As shown in FIG. 7, in the bending sensor 1a, the base material 12 includes a first portion P1 located in the first region A11 and a second portion P2 located in the bending portion BP when viewed in the Z direction. The bending sensor 1a is different from the bending sensor 1 in that the elastic modulus of the first portion P1 is lower than the elastic modulus of the second portion P2.
[0043] The bending sensor 1a also has the same effect as the bending sensor 1. Further, according to the bending sensor 1a, the sensitivity of the piezoelectric element 14 can be improved. More specifically, since the elastic modulus of the first portion P1 is lower than the elastic modulus of the second portion P2, the amount of expansion and contraction of the first portion P1 increases during bending. Therefore, the piezoelectric film 141 is more likely to expand along the Y direction during bending. As a result, the piezoelectric film 141 is more likely to generate a voltage during bending, and the sensitivity of the piezoelectric element 14 can be improved.
[0044] [Second Modified Example] Hereinafter, the bending sensor 1b according to the second modified example of the present invention and the electronic device 100b including the bending sensor 1b will be described with reference to the drawings. FIG. 8 is a plan view of the electronic device 100b. Note that only the portions different from the bending sensor 1 and the electronic device 100 will be described for the bending sensor 1b and the electronic device 100b, respectively, and the description thereof will be omitted later.
[0045] As shown in FIG. 8, the bending sensor 1b is different from the bending sensor 1 in that the adhesive 11 includes adhesives 111 and 112. In this modified example, the adhesive 11 does not cover the entire first main surface MS1 of the base material 12. The adhesive 111 is located in the first region A11 when viewed in the Z direction. The adhesive 112 is located in the first region A12 when viewed in the Z direction. That is, the adhesive 11 is not located in the bending portion BP when viewed in the Z direction.
[0046] Also in the bending sensor 1b, the same effect as that of the bending sensor 1 is achieved. Further, according to the bending sensor 1b, it is possible to suppress a mechanical load from being applied to the base material 12 during bending. More specifically, in the bending sensor 1b, the adhesive 11 is not located in the bending portion BP when viewed in the Z direction. Therefore, the base material 12 is not attached to the surface panel 102 at the bending portion BP where stress concentrates during bending, and it is difficult for a mechanical load to be applied to the base material 12 during bending. As a result, according to the bending sensor 1b, it is possible to suppress a mechanical load from being applied to the base material 12 during bending.
[0047] [Third Modified Example] Hereinafter, the bending sensor 1c according to the third modified example of the present invention and the electronic device 100c including the bending sensor 1c will be described with reference to the drawings. FIG. 9 is a perspective view of the electronic device 100c. FIG. 10 is a plan view of the electronic device 100c. Note that only the parts of the bending sensor 1c and the electronic device 100c that are different from the bending sensor 1 and the electronic device 100, respectively, will be described, and the rest will be omitted.
[0048] As shown in FIG. 9, the bending sensor 1c is different from the bending sensor 1 in that the length in the Y direction is short. More specifically, as shown in FIG. 10, in the electronic device 100c, the base material 12 is located across the first region A11 and the bending portion BP and is not located in the first region A12. More specifically, the base material 12 is located across the first region A11, the first bending region BA1, and the second bending region BA2.
[0049] Also in the bending sensor 1c, the same effect as that of the bending sensor 1 is achieved.
[0050] [Fourth Modification] Below, a bending sensor 1d and an electronic device 100d equipped with the bending sensor 1d according to the fourth modification of the present invention will be described with reference to the drawings. Figure 11 is a plan view of the electronic device 100d. Note that only the parts of the bending sensor 1d and the electronic device 100d that differ from the bending sensor 1 and the electronic device 100, respectively, will be described, and the rest will be omitted.
[0051] As shown in Figure 11, the bending sensor 1d differs from the bending sensor 1 in that the adhesive 13 includes adhesives 131 and 132. In this modified example, the adhesive 13 does not cover the entire third main surface MS3 of the piezoelectric element 14. Each of the adhesives 131 and 132 extends in the Y direction. Adhesive 131 is located at the X-direction end of the third main surface MS3. Adhesive 132 is located at the opposite end of the third main surface MS3 in the X direction. Adhesives 131 and 132 each correspond to the fourth adhesive according to the present invention.
[0052] The bending sensor 1d achieves the same effect as the bending sensor 1. Furthermore, the bending sensor 1d allows for a reduction in the amount of adhesive used.
[0053] [Fifth Modification] Below, a fifth modification of the present invention, specifically a bending sensor 1e and an electronic device 100e equipped with the bending sensor 1e, will be described with reference to the drawings. Figure 12 is a plan view of the electronic device 100e. Note that only the parts of the bending sensor 1e and the electronic device 100e that differ from the bending sensor 1 and the electronic device 100, respectively, will be described, and the rest will be omitted.
[0054] As shown in Figure 12, the bending sensor 1e differs from the bending sensor 1 in that the adhesive 13 includes adhesives 131 and 132. In this modified example, the adhesive 13 does not cover the entire third main surface MS3 of the piezoelectric element 14. Each of the adhesives 131 and 132 extends in the X direction. Adhesive 131 is located at the end of the third main surface MS3 opposite to the Y direction. Adhesive 132 is located at the end of the third main surface MS3 in the Y direction. Also, adhesives 131 and 132 are spaced apart from each other along the Y direction. Adhesives 131 and 132 each correspond to the fourth adhesive according to the present invention.
[0055] The bending sensor 1e also produces the same effect as the bending sensor 1. Furthermore, the bending sensor 1e can improve the sensitivity of the piezoelectric element 14. More specifically, by positioning the adhesive 131 at the Y-direction end of the third main surface MS3 of the piezoelectric element 14, and the adhesive 132 at the opposite Y-direction end of the third main surface MS3 of the piezoelectric element 14, and arranging the adhesives 131 and 132 with a gap between them along the Y-direction, the piezoelectric film 141 becomes easier to stretch along the Y-direction when bent. As a result, the piezoelectric film 141 becomes easier to generate voltage when bent, and the sensitivity of the piezoelectric element 14 can be improved.
[0056] [Sixth Modification] Below, a bending sensor 1f and an electronic device 100f equipped with the bending sensor 1f according to the sixth modification of the present invention will be described with reference to the drawings. Figure 13 is a plan view of the electronic device 100f. Note that only the parts of the bending sensor 1f and the electronic device 100f that differ from the bending sensor 1 and the electronic device 100, respectively, will be described, and the rest will be omitted.
[0057] As shown in Figure 13, the bending sensor 1f differs from the bending sensor 1 in that the adhesive 13 includes adhesives 131, 132, 133, and 134. In this modified example, the adhesive 13 does not cover the entire third main surface MS3 of the piezoelectric element 14. The adhesives 131, 132, 133, and 134 are each located at one of the four corners of the third main surface MS3. Adhesive 131 is located at the end of the third main surface MS3 opposite to the Y direction and at the end in the X direction. Adhesive 132 is located at the end of the third main surface MS3 opposite to the Y direction and at the end in the X direction. Adhesive 133 is located at the end of the third main surface MS3 opposite to the X direction. Adhesive 134 is located at the end of the third main surface MS3 opposite to the Y direction and at the end in the X direction. The adhesives 131 and 134 are spaced apart from each other along the Y direction. The adhesives 132 and 133 are arranged along the Y direction, spaced apart from each other. The adhesives 131, 132, 133, and 134 each correspond to the fourth adhesive according to the present invention.
[0058] The bending sensor 1f also produces the same effect as the bending sensor 1. Furthermore, the bending sensor 1f, like the bending sensor 1e, can improve the sensitivity of the piezoelectric element 14.
[0059] [Seventh Modification] Below, a bending sensor 1g and an electronic device 100g equipped with the bending sensor 1g according to the seventh modification of the present invention will be described with reference to the drawings. Figure 14 is a plan view of the electronic device 100g. Note that only the parts of the bending sensor 1g and the electronic device 100g that differ from the bending sensor 1 and the electronic device 100, respectively, will be described, and the rest will be omitted.
[0060] As shown in Figure 14, the bending sensor 1g differs from the bending sensor 1 in that the adhesive 13 includes adhesives 131, 132, and 133. In this modified example, the adhesive 13 does not cover the entire third main surface MS3 of the piezoelectric element 14. Adhesive 131 extends in the X direction. Adhesive 131 is located at the end of the third main surface MS3 opposite to the Y direction. Adhesive 132 is located at the end of the third main surface MS3 in the Y direction and opposite to the X direction. Adhesive 133 is located at the end of the third main surface MS3 in the Y direction and at the end in the X direction. Adhesives 131 and 132 are spaced apart from each other along the Y direction. Adhesives 131 and 133 are spaced apart from each other along the Y direction. Adhesives 131, 132, and 133 each correspond to the fourth adhesive according to the present invention.
[0061] The bending sensor 1g also produces the same effect as the bending sensor 1. Furthermore, the bending sensor 1g, like the bending sensors 1e and 1f, can improve the sensitivity of the piezoelectric element 14.
[0062] [Eighth Modification] Below, a bending sensor 1h and an electronic device 100h equipped with the bending sensor 1h according to the eighth modification of the present invention will be described with reference to the drawings. Figure 15 is a plan view of the electronic device 100h. Note that only the parts of the bending sensor 1h and the electronic device 100h that differ from the bending sensor 1 and the electronic device 100, respectively, will be described, and the rest will be omitted.
[0063] As shown in Figure 15, the bending sensor 1h differs from the bending sensor 1 in that the adhesive 13 includes adhesives 131, 132, and 133. In this modified example, the adhesive 13 does not cover the entire third main surface MS3 of the piezoelectric element 14. Adhesive 131 is located at the end of the third main surface MS3 opposite to the Y direction and at the end in the X direction. Adhesive 132 is located at the end of the third main surface MS3 opposite to the Y direction and at the end in the X direction. Adhesive 133 extends in the X direction. Adhesive 133 is located at the end of the third main surface MS3 in the Y direction. Adhesives 131 and 133 are spaced apart from each other along the Y direction. Adhesives 132 and 133 are spaced apart from each other along the Y direction. Adhesives 131, 132, and 133 each correspond to the fourth adhesive according to the present invention.
[0064] The bending sensor 1h also produces the same effect as the bending sensor 1. Furthermore, the bending sensor 1h, like the bending sensors 1e to 1g, can improve the sensitivity of the piezoelectric element 14.
[0065] [Second Embodiment] Below, a bending sensor 1i and an electronic device 100i equipped with the bending sensor 1i according to a second embodiment of the present invention will be described with reference to the drawings. Figure 16 is a cross-sectional view of the electronic device 100i taken along the line A-A shown in Figure 1A. Figure 17 is a plan view of the electronic device 100i. Figure 18 is a cross-sectional view showing the electronic device 100i being bent. Note that in Figure 18, the housing 101 and adhesives 11 and 15 are omitted for the sake of clarity.
[0066] As shown in Figure 16, the bending sensor 1i differs from the bending sensor 1 in that it further includes an adhesive 15.
[0067] In this embodiment, the adhesive 11 does not cover the entire first main surface MS1 of the substrate 12. As shown in Figures 16 and 17, the adhesive 11 is provided on the portion of the first main surface MS1 located in the first region A12 when viewed in the Z direction. As a result, the first main surface MS1 is attached to the first region A12 by the adhesive 11.
[0068] In this embodiment, the fourth main surface MS4 of the piezoelectric element 14 is fixed to the first main surface MS1 of the substrate 12 by an adhesive 13 that covers the entire fourth main surface MS4. The third main surface MS3 of the piezoelectric element 14 is attached to the surface panel 102 by an adhesive 15 that covers the entire third main surface MS3. Therefore, the piezoelectric element 14 is located between the surface panel 102 and the substrate 12 in the Z direction. Furthermore, in this embodiment, the first main surface MS1 of the substrate 12 and the third main surface MS3 of the piezoelectric element 14 are attached to the surface panel 102. The adhesive 15 is, for example, a double-sided tape such as OCA. Note that the adhesive 13 does not necessarily cover the entire fourth main surface MS4. Also, the adhesive 15 does not necessarily cover the entire third main surface MS3. Furthermore, the adhesive 15 is not limited to OCA. The adhesive 15 corresponds to the second adhesive according to the present invention.
[0069] As shown in Figure 18, when the electronic device 100i is not bent, both the substrate 12 and the piezoelectric element 14 are at their natural length, and the piezoelectric film 141 does not generate voltage.
[0070] When the electronic device 100i is bent, the base material 12 is stretched and compressed at the bent portion BP. More specifically, at the bent portion BP, the first main surface MS1 of the base material 12 is compressed toward the bend line L. On the other hand, at the bent portion BP, the second main surface MS2 of the base material 12 is stretched. Specifically, in the first bending region BA1, the second main surface MS2 stretches toward the first region A11. In the second bending region BA2, the second main surface MS2 stretches toward the first region A12. Consequently, in the first region A11, the base material 12 stretches toward the first bending region BA1. Also, in the first region A12, the base material 12 stretches toward the second bending region BA2. At this time, the piezoelectric element 14 provided in the first region A11 stretches toward the first bending region BA1. Therefore, the piezoelectric film 141 stretches along the Y direction. As a result, the piezoelectric film 141 generates a voltage.
[0071] The bending sensor 1i also produces the same effect as the bending sensor 1.
[0072] [Third Embodiment] Below, an electronic device 100j according to a third embodiment of the present invention will be described with reference to the drawings. Figure 19 is a side view of the electronic device 100j. Note that in Figure 19, the housing 101 and adhesive 11 are omitted for the sake of clarity. Figure 20 is a top view of the electronic device 100j. Note that only the parts of the electronic device 100j that differ from the electronic device 100 will be described, and the rest will be omitted.
[0073] Electronic device 100j differs from electronic device 100 in that it includes two hinges 16 and two bending sensors 1.
[0074] As shown in Figure 19, the positions of the two hinges 16 in the Y direction are different. Therefore, the electronic device 100j (surface panel 102) can be folded into three. In Figure 19, of the two hinges 16, the hinge 16 located on the left is called the first hinge 161, and the hinge 16 located on the right is called the second hinge 162. In this embodiment, the two hinges 16 are provided on different main surfaces of the two opposing main surfaces of the surface panel 102. The first hinge 161 is provided on the surface panel 102 that is on the outside of the housing 101. The second hinge 162 is provided on the surface panel 102 that is on the inside of the housing 101.
[0075] Due to the presence of two hinges 16, the surface panel 102 has two bent portions BP. The bent portion BP located on the first hinge 161 is designated as the first bent portion BP1, and the bent portion BP located on the second hinge 162 is designated as the second bent portion BP2. When the surface panel 102 is folded inward by the first hinge 161, the first bent portion BP1 bends. At this time, the first region A1 adjacent to the first bent portion BP1 does not bend. In Figure 19, the first region A1 located to the left of the first bent portion BP1 is designated as the first region A13, and the first region A1 located to the right of the first bent portion BP1 is designated as the first region A14.
[0076] When the surface panel 102 is folded outward by the second hinge 162, the second bend portion BP2 bends. At this time, the second region A2 adjacent to the second bend portion BP2 does not bend. In Figure 19, the second region A2 located to the left of the second bend portion BP2 is designated as the second region A21, and the second region A2 located to the right of the second bend portion BP2 is designated as the second region A22.
[0077] In other words, the presence of two hinges 16 gives the surface panel 102 a first bend BP1, a first region A1, a second bend BP2, and a second region A2. The first region A1 and the second region A2 are different from each other, but may overlap in part.
[0078] The two bending sensors 1 are located at different positions in the Y-direction. In Figure 19, of the two bending sensors 1, the one located on the left is designated as the first bending sensor 21, and the one located on the right is designated as the second bending sensor 22. The first bending sensor 21 detects whether or not the surface panel 102 (electronic device 100j) is bent by the first hinge 161, and the state of the bend (current opening / closing angle). The second bending sensor 22 detects whether or not the surface panel 102 (electronic device 100j) is bent by the second hinge 162, and the state of the bend (current opening / closing angle). In this embodiment, the first bending sensor 21 is attached to the surface of the surface panel 102 that is on the inside of the housing 101. The second bending sensor 22 is attached to the surface of the surface panel 102 that is on the outside of the housing 101. The first bending sensor 21 may be attached to the outer surface of the housing 101 of the surface panel 102, and the second bending sensor 22 may be attached to the inner surface of the housing 101 of the surface panel 102.
[0079] As shown in Figure 20, the base material 12 of the first bending sensor 21 is positioned across the first region A13, the first bending portion BP1, and the first region A14. That is, the base material 12 of the first bending sensor 21 is positioned across the first bending portion BP1 and the first region A1. In this embodiment, the base material 12 of the first bending sensor 21 does not reach the second bending portion BP2 and the second region A22. The length of the base material 12 of the first bending sensor 21 in the Y direction is 1.2 times or more the length of the piezoelectric element 14 of the first bending sensor 21 in the Y direction. In this embodiment, the length of the base material 12 of the first bending sensor 21 in the Y direction is approximately 4.4 times the length of the piezoelectric element 14 of the first bending sensor 21 in the Y direction. The base material 12 of the first bending sensor 21 may reach the second bending portion BP2 and the second region A22. The Y direction corresponds to the longitudinal direction of the adherend according to the present invention.
[0080] Furthermore, it is more preferable that the length of the substrate 12 of the first bending sensor 21 in the Y direction be 1.5 times or more the length of the piezoelectric element 14 of the first bending sensor 21 in the Y direction, and even more preferable that it be 2.0 times or more the length of the piezoelectric element 14 of the first bending sensor 21 in the Y direction.
[0081] The piezoelectric element 14 of the first bending sensor 21 is located in the first region A13. That is, the piezoelectric element 14 of the first bending sensor 21 is located in the first region A1 and is not located in the first bending portion BP1 or the second bending portion BP2.
[0082] The base material 12 of the second bending sensor 22 is positioned across the second region A21, the second bending portion BP2, and the second region A22. That is, the base material 12 of the second bending sensor 22 is positioned across the second bending portion BP2 and the second region A2. In this embodiment, the base material 12 of the second bending sensor 22 does not reach the first bending portion BP1 and the first region A13. The length of the base material 12 of the second bending sensor 22 in the Y direction is 1.2 times or more the length of the piezoelectric element 14 of the second bending sensor 22 in the Y direction. In this embodiment, the length of the base material 12 of the second bending sensor 22 in the Y direction is approximately 4.4 times the length of the piezoelectric element 14 of the second bending sensor 22 in the Y direction. The base material 12 of the second bending sensor 22 may reach the first bending portion BP1 and the first region A13.
[0083] Furthermore, it is more preferable that the length of the base material 12 of the second bending sensor 22 in the Y direction be 1.5 times or more the length of the piezoelectric element 14 of the second bending sensor 22 in the Y direction, and even more preferable that it be 2.0 times or more the length of the piezoelectric element 14 of the second bending sensor 22 in the Y direction.
[0084] The piezoelectric element 14 of the second bending sensor 22 is located in the second region A22. That is, the piezoelectric element 14 of the second bending sensor 22 is located in the second region A2 and is not located in the first bending portion BP1 or the second bending portion BP2.
[0085] In this embodiment, when viewed in the Z direction, the center O114 of the piezoelectric element 14 of the first bending sensor 21 is located in the center of the surface panel 102 in the X direction. Also, when viewed in the Z direction, the center O214 of the piezoelectric element 14 of the second bending sensor 22 is located in the center of the surface panel 102 in the X direction. When viewed in the Y direction, the center O114 of the piezoelectric element 14 of the first bending sensor 21 and the center O214 of the piezoelectric element 14 of the second bending sensor 22 overlap each other.
[0086] The same effect is achieved in the electronic device 100j as in the electronic device 100. Furthermore, in the electronic device 100j, the surface panel 102 may have two bent portions BP. Similarly, the surface panel 102 may have three or more bent portions BP.
[0087] Furthermore, when viewed in the Y direction, the center O114 of the piezoelectric element 14 of the first bending sensor 21, when viewed in the Z direction, does not have to coincide with the center O214 of the piezoelectric element 14 of the second bending sensor 22, when viewed in the Z direction. Figure 21 is a plan view of the electronic device 100j with a changed arrangement of piezoelectric elements 14. As shown in Figure 21, when viewed in the Z direction, the center O114 of the piezoelectric element 14 of the first bending sensor 21 does not have to be located in the center of the surface panel 102 in the X direction. Also, when viewed in the Z direction, the center O214 of the piezoelectric element 14 of the second bending sensor 22 does not have to be located in the center of the surface panel 102 in the X direction.
[0088] In addition, the piezoelectric element 14 of the first bending sensor 21 may be located in the first region A14, and the piezoelectric element 14 of the second bending sensor 22 may be located in the second region A21. Figure 22 is a side view of the electronic device 100j with a changed arrangement of the piezoelectric elements 14. In Figure 22, the housing 101 and adhesive 11 are omitted for the sake of clarity. In this case as well, as shown in Figure 22, it is sufficient that the piezoelectric elements 14 of the first bending sensor 21 and the second bending sensor 22 are not located in the first bending portion BP1 and the second bending portion BP2.
[0089] Furthermore, when viewed in the Z direction, the center O114 of the piezoelectric element 14 of the first bending sensor 21 and the center O214 of the piezoelectric element 14 of the second bending sensor 22 may overlap each other. Figure 23 is a side view of the electronic device 100j with a changed arrangement of piezoelectric elements 14. Note that in Figure 23, the housing 101 and adhesive 11 are omitted for the sake of clarity. In this case as well, as shown in Figure 23, it is sufficient that the piezoelectric elements 14 of the first bending sensor 21 and the second bending sensor 22 are not located in the first bending portion BP1 and the second bending portion BP2.
[0090] The piezoelectric element 14 of the first bending sensor 21 may be located on the positive side in the Y direction relative to the piezoelectric element 14 of the second bending sensor 22. Figure 24 is a side view of the electronic device 100j with a modified arrangement of the piezoelectric elements 14. In Figure 24, the housing 101 and adhesive 11 are omitted for the sake of clarity. In this case as well, as shown in Figure 24, the piezoelectric elements 14 of the first bending sensor 21 and the second bending sensor 22 do not need to be located in the first bending portion BP1 and the second bending portion BP2.
[0091] In addition, the piezoelectric element 14 of the first bending sensor 21 may be located in the first region A13, and the piezoelectric element 14 of the second bending sensor 22 may be located in the second region A21. Figure 25 is a side view of the electronic device 100j with a changed arrangement of the piezoelectric elements 14. In Figure 25, the housing 101 and adhesive 11 are omitted for the sake of clarity. In this case as well, as shown in Figure 25, it is sufficient that the piezoelectric elements 14 of the first bending sensor 21 and the second bending sensor 22 are not located in the first bending portion BP1 and the second bending portion BP2.
[0092] Furthermore, the electronic device 100j does not need to be equipped with a hinge 16.
[0093] [Fourth Embodiment] Below, an electronic device 100k according to the fourth embodiment of the present invention will be described with reference to the drawings. Figure 26 is a side view of the electronic device 100k. Note that in Figure 26, the housing 101 and adhesive 11 are omitted for the sake of clarity. Only the parts of the electronic device 100k that differ from the electronic device 100j will be described, and the rest will be omitted.
[0094] Electronic device 100k differs from electronic device 100j in that the two hinges 16 are provided on the same surface of the surface panel 102.
[0095] In this embodiment, as shown in Figure 26, the first hinge 161 and the second hinge 162 are each provided on the surface panel 102 that faces inward from the housing 101. As a result, when the surface panel 102 is bent outward by the first hinge 161, the first bent portion BP1 bends. At this time, the first region A1 adjacent to the first bent portion BP1 does not bend. Alternatively, the first hinge 161 and the second hinge 162 may each be provided on the surface panel 102 that faces outward from the housing 101.
[0096] In this embodiment, the first bending sensor 21 and the second bending sensor 22 are each attached to the inner surface of the surface panel 102 that faces the housing 101. Alternatively, the first bending sensor 21 and the second bending sensor 22 may be attached to the outer surface of the surface panel 102 that faces the housing 101.
[0097] In this embodiment as well, when viewed in the Y direction, the center O114 of the piezoelectric element 14 of the first bending sensor 21 and the center O214 of the piezoelectric element 14 of the second bending sensor 22 may or may not overlap with each other.
[0098] The same effect is achieved in electronic equipment 100k as in electronic equipment 100j.
[0099] In addition, the piezoelectric element 14 of the first bending sensor 21 may be located in the first region A14, and the piezoelectric element 14 of the second bending sensor 22 may be located in the second region A21. Figure 27 is a side view of the electronic device 100k with a changed arrangement of the piezoelectric elements 14. In Figure 27, the housing 101 and adhesive 11 are omitted for the sake of clarity. In this case as well, as shown in Figure 27, it is sufficient that the piezoelectric elements 14 of the first bending sensor 21 and the second bending sensor 22 are not located in the first bending portion BP1 and the second bending portion BP2.
[0100] In addition, the piezoelectric element 14 of the first bending sensor 21 may be located in the first region A13, and the piezoelectric element 14 of the second bending sensor 22 may be located in the second region A21. Figure 28 is a side view of the electronic device 100k with a changed arrangement of the piezoelectric elements 14. In Figure 28, the housing 101 and adhesive 11 are omitted for the sake of clarity. In this case as well, as shown in Figure 28, it is sufficient that the piezoelectric elements 14 of the first bending sensor 21 and the second bending sensor 22 are not located in the first bending portion BP1 and the second bending portion BP2.
[0101] Furthermore, like electronic device 100j, electronic device 100k does not need to be equipped with a hinge 16.
[0102] [Other Embodiments] The bending sensor according to the present invention is not limited to bending sensors 1, 1a to 1i, but can be modified within the scope of its gist. Furthermore, the structures of bending sensors 1, 1a to 1i may be combined in any way.
[0103] The electronic devices according to the present invention are not limited to electronic devices 100, 100a to 100k, but can be modified within the scope of the gist thereof. Furthermore, the structures of electronic devices 100, 100a to 100k may be arbitrarily combined.
[0104] Furthermore, the length of the base material 12 of the bending sensors 1, 1a to 1i in the Y direction is preferably 1.2 times or more the length of the piezoelectric element 14 of the bending sensors 1, 1a to 1i in the Y direction, more preferably 1.5 times or more the length of the piezoelectric element 14 of the bending sensors 1, 1a to 1i in the Y direction, and even more preferably 2.0 times or more the length of the piezoelectric element 14 of the bending sensors 1, 1a to 1i in the Y direction.
[0105] For example, the structure of any of the bending sensors 1e to 1h may be combined with the structure of the bending sensor 1i. That is, in the bending sensor 1i, the arrangement of the adhesive 13 may be the same as the arrangement of the adhesive 13 for any of the bending sensors 1e to 1h. Figure 29 is a side view of an electronic device 100i in which the arrangement of the adhesive 13 is the same as the arrangement of the adhesive 13 for any of the bending sensors 1e to 1h. Note that in Figure 29, the housing 101 is omitted for the sake of clarity. The adhesive 13 includes a plurality of adhesives 135. The adhesives 135 correspond to the fourth adhesive according to the present invention. In such a bending sensor 1i, the sensitivity of the piezoelectric element 14 can be improved, similar to the bending sensors 1e to 1h. In this case, furthermore, in a plan view, the arrangement of the adhesive 15 may be the same as the arrangement of the adhesive 13 for the bending sensor 1d. In this case, the adhesive 15 includes a plurality of adhesives 151. Each of the plurality of adhesives 151 extends in the Y direction. The multiple adhesives 151 are located at the X-direction end of the third main surface MS3 of the piezoelectric element 14, and at the opposite X-direction end of the third main surface MS3 of the piezoelectric element 14. The multiple adhesives 151 correspond to the multiple third adhesives according to the present invention. In such a bending sensor 1i, as with the bending sensor 1d, the amount of adhesive used can be reduced.
[0106] In the bending sensor 1i, the arrangement of the adhesive 15 in a plan view may be the same as the arrangement of the adhesive 13 for any of the bending sensors 1e to 1h. Figure 30 is a side view of an electronic device 100i in which the arrangement of the adhesive 15 in a plan view is the same as the arrangement of the adhesive 13 for any of the bending sensors 1e to 1h. Note that in Figure 30, the housing 101 is omitted for the sake of clarity. The adhesive 15 includes a plurality of adhesives 151. The plurality of adhesives 151 are located at the Y-direction end of the third main surface MS3 of the piezoelectric element 14 and at the opposite Y-direction end of the third main surface MS3 of the piezoelectric element 14, and are arranged at intervals from each other along the Y-direction. The plurality of adhesives 151 correspond to a plurality of third adhesives according to the present invention. In such a bending sensor 1i, the sensitivity of the piezoelectric element 14 can be improved, similar to the bending sensors 1e to 1h.
[0107] 1, 1a-1i: Bending sensor 11, 13, 15, 111, 112, 131-135, 151: Adhesive 12: Substrate 14: Piezoelectric element 16: Hinge 21: First bending sensor 22: Second bending sensor 100, 100a-100k: Electronic equipment 101: Housing 102: Surface panel 141: Piezoelectric film 142: Reference electrode 143: Signal electrode 144: FPC 145: Shielding member 161: First hinge 162: Second hinge A1, A11-A14: First region A2, A21, A22: Second region BA1: First bending region BA2: Second bending region BEP: Bending point BP: Bending part BP1: First bending part BP2: Second bending part L: Folding line MS1: First main surface MS11, MS14: Main surfaces MS2: Second main surface MS3: Third main surface MS4: Fourth main surface MS5: Fifth main surface MS6: Sixth main surface MS7: Seventh main surface MS8: Eighth main surface O114, O214: Center OD: Stretching direction P1: First part P2: Second part
Claims
1. A bend sensor to be attached to a bendable adherend having a bend portion that bends when bent and a first region adjacent to the bend portion, comprising: a flexible substrate having a main surface; a piezoelectric element having a main surface; and a first adhesive for fixing the main surface of the piezoelectric element to the main surface of the substrate, wherein the main surface of the substrate is attached to the adherend, the substrate is positioned across the bend portion and the first region, and the piezoelectric element is located in the first region and not in the bend portion.
2. The bending sensor according to claim 1, wherein the main surface of the substrate includes opposing first main surface and second main surface, the main surface of the piezoelectric element includes opposing third main surface and fourth main surface, the first main surface is attached to the adherend, and the third main surface is fixed to the second main surface by the first adhesive.
3. The bending sensor according to claim 1, further comprising a second adhesive, wherein the main surface of the substrate includes opposing first and second main surfaces, the main surface of the piezoelectric element includes opposing third and fourth main surfaces, the first main surface is attached to the first region, the fourth main surface is fixed to the first main surface by the first adhesive, and the third main surface is attached to the adherend by the second adhesive.
4. The bending sensor according to claim 3, wherein the second adhesive comprises a plurality of third adhesives, and the third adhesives extend in a first direction in which the bending portion and the first region are aligned.
5. The bending sensor according to claim 3 or claim 4, wherein the second adhesive comprises a plurality of third adhesives, the plurality of third adhesives are located at the end of the main surface of the piezoelectric element in the first direction where the bent portion and the first region are aligned, and at the end of the main surface of the piezoelectric element in the opposite direction to the first direction, and are arranged at intervals from each other along the first direction.
6. The bending sensor according to any one of claims 1 to 5, wherein the first adhesive comprises a plurality of fourth adhesives, and the fourth adhesives extend in a first direction in which the bending portion and the first region are aligned.
7. The bending sensor according to any one of claims 1 to 6, wherein the first adhesive comprises a plurality of fourth adhesives, the plurality of fourth adhesives are located at the end of the main surface of the piezoelectric element in the first direction where the bent portion and the first region are aligned, and at the end of the main surface of the piezoelectric element in the opposite direction to the first direction, and are arranged at intervals from each other along the first direction.
8. The bending sensor according to any one of claims 1 to 7, wherein the elastic modulus of the first portion of the substrate located in the first region is lower than the elastic modulus of the second portion of the substrate located in the bending portion.
9. An electronic device comprising: a bending sensor according to any one of claims 1 to 8; and the adherend.
10. A flexible adherend, a first bending sensor attached to the adherend, and a second bending sensor attached to the adherend, wherein the adherend has a first bending portion that bends when bent, and a second bending portion that bends when bent and is different from the first bending portion, and each of the first bending sensor and the second bending sensor is flexible and comprises a substrate having a main surface attached to the adherend, a piezoelectric element having a main surface, and a first adhesive for fixing the main surface of the piezoelectric element to the main surface of the substrate, wherein the length of the substrate in the longitudinal direction of the adherend is 1.2 times or more the length of the piezoelectric element in the longitudinal direction, the substrate of the first bending sensor is located across the first bending portion and a first region adjacent to the first bending portion, and the piezoelectric element of the first bending sensor is located in the first region and not in the first bending portion or the second bending portion. The substrate of the second bending sensor is located across the second bending portion and a second region adjacent to the second bending portion, and the piezoelectric element of the second bending sensor is located in the second region and not in the first bending portion or the second bending portion, in an electronic device.