Deformation amount detecting device

Abstract

To provide a deformation amount detection device for detecting a deformation amount with high sensitivity by using resonance in a thickness direction.SOLUTION: A substrate having a first end and a second end that are both ends along a first direction, the first end side and the second end side being fixed to the substrate; a piezoelectric body that overlaps the substrate in plan view and is disposed between the first end and the second end; A first electrode disposed on a first main surface of the piezoelectric body, a second electrode overlapping the piezoelectric body in plan view and disposed on a second main surface of the piezoelectric body, and a controller connected to the first electrode and the second electrode, wherein the first end and the second end of the substrate have different lengths and resonate in a thickness direction, and the controller measures a resonance frequency of the substrate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a deformation amount detection device. [Background technology]

[0002] Patent Document 1 discloses a deformation amount detection device including a first electrode, a second electrode, and a flexible transmission part.

[0003] In the configuration of Patent Document 1, when an input signal is input to a first electrode, an elastic wave is generated. The transmission unit transmits the elastic wave to a second electrode. The second electrode generates an output signal in response to the elastic wave. In the configuration of Patent Document 1, the amount of deformation of the transmission unit from a reference state can be detected based on the output signal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 030356 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of one embodiment of the present invention is to provide a deformation amount detection device that detects the amount of deformation with high sensitivity by utilizing resonance in the thickness direction. [Means for solving the problem]

[0006] A deformation detection device according to one embodiment of the present invention includes a substrate having a first end and a second end that are opposite ends along a first direction, the first end side and the second end side being fixed, a piezoelectric body that overlaps the substrate in a planar view and is arranged between the first end and the second end, a first electrode that overlaps the piezoelectric body in a planar view and is arranged on a first main surface of the piezoelectric body, a second electrode that overlaps the piezoelectric body in a planar view and is arranged on a second main surface of the piezoelectric body, and a controller connected to the first electrode and the second electrode, wherein the substrate has different lengths at the first end and the second end and resonates in the thickness direction, and the controller measures the resonant frequency of the substrate.

[0007] The inventors of the present application discovered that when a piezoelectric body is placed on a substrate whose first and second ends have different lengths and is vibrated, a resonance phenomenon in the thickness direction called a flapping mode occurs, and the resonance frequency of this flapping mode changes depending on the amount of deformation of the substrate. Therefore, the present invention can detect the amount of deformation with high sensitivity by measuring the resonance frequency of the substrate using a controller. [Effects of the Invention]

[0008] According to one embodiment of the present invention, the amount of deformation can be detected with high sensitivity by utilizing resonance in the thickness direction. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a deformation amount detection device 1. [Figure 2] FIG. 2 is a plan view of the deformation amount detection device 1. [Figure 3] FIG. 3 is a cross-sectional view taken along line II in FIG. 2. [Figure 4] FIG. 2 is a plan view of the deformation amount detection device 1. [Figure 5] 1 is a schematic diagram showing how the substrate 10 vibrates. [Figure 6] 10 shows the relationship between the bending angle of the substrate 10 and the resonance frequency of the substrate 10 measured by the controller 90. [Figure 7]10 is a plan view showing a modified example of the arrangement of the piezoelectric body 30. FIG. [Figure 8] 10 is a plan view showing a modified example of the arrangement of the piezoelectric body 30. FIG. [Figure 9] Figure 9(A) is a schematic diagram showing the vibration of the substrate 10 in the arrangement of the piezoelectric body 30 shown in Figure 7, and Figure 9(B) is a schematic diagram showing the vibration of the substrate 10 when the piezoelectric body 30 is arranged on the first end 101 side of the substrate 10. [Figure 10] FIG. 10 is a cross-sectional view of a deformation amount detecting device 1 according to a first modified example. [Figure 11] 10 shows the relationship between the bending angle of the substrate 10 and the resonance frequency of the substrate 10 measured by the controller 90. [Figure 12] FIG. 10 is a plan view of a deformation amount detecting device 1 according to a second modification. [Figure 13] 1 is a schematic diagram showing how the substrate 10 vibrates. [Figure 14] 10 shows the relationship between the bending angle of the substrate 10 and the resonance frequency of the substrate 10 measured by the controller 90. DETAILED DESCRIPTION OF THE INVENTION

[0010] Fig. 1 is an external perspective view of the deformation amount detecting device 1. Fig. 2 is a plan view of the deformation amount detecting device 1. Fig. 3 is a cross-sectional view taken along line II shown in Fig. 2.

[0011] The deformation amount detecting device 1 has a substrate 10, a first fixing portion 15, a second fixing portion 17, a piezoelectric body 30, a first electrode 21, a second electrode 22, and a controller 90.

[0012] Substrate 10 is made of, for example, PET, polycarbonate (PC), acrylic (PMMA), stainless steel, an aluminum alloy, or a copper alloy. Substrate 10 has a first end 101 and a second end 102, which are opposite ends along a first direction. The underside of substrate 10 on the side of first end 101 is fixed to detection object 70 by first fixing portion 15. The underside of substrate 10 on the side of second end 102 is fixed to detection object 70 by second fixing portion 17. First fixing portion 15 and second fixing portion 17 are, for example, adhesive tape.

[0013] In the following description, the first direction, which is the longitudinal direction of the substrate 10, is defined as the Y direction, the thickness direction of the substrate 10 is defined as the Z direction, and the short side direction of the substrate 10, which is perpendicular to the Y direction in a plan view, is defined as the X direction.

[0014] In plan view, the first end 101 and the second end 102 of the substrate 10 have different lengths in the X direction. In this example, the length of the first end 101 in the X direction is longer than the length of the second end 102 in the X direction. The shape of the substrate 10 in plan view is trapezoidal, with two long sides along the Y direction being oblique sides inclined with respect to the X and Y directions, respectively. However, in the present invention, the shape of the substrate 10 is not particularly limited as long as the lengths of the first end 101 and the second end 102 in the X direction are different. For example, as in the substrate 10 shown in FIG. 4, one of the two long sides along the Y direction may be perpendicular to the X direction and parallel to the Y direction.

[0015] The deformation amount detection device 1 detects the amount of deformation of a flexible substrate 10 from a reference state. In this embodiment, the deformation amount detection device 1 detects the angle when the substrate 10 is bent in the Z direction along the Y direction. In this way, the deformation amount detection device 1 detects the amount of deformation of the detection object 70 in the Z direction.

[0016] A second electrode 22 is disposed on the upper surface of substrate 10. Second electrode 22 is disposed at a position overlapping with substrate 10 in a plan view. Second electrode 22 has a trapezoidal shape similar to substrate 10 in a plan view. However, second electrode 22 does not overlap with first fixed portion 15 and second fixed portion 17 in a plan view.

[0017] The second electrode 22 is, for example, an inorganic electrode such as ITO (indium tin oxide) or ZnO (zinc oxide), an organic electrode such as PeDOT or conductive polyaniline, a metal film formed by vapor deposition or plating, or a printed electrode film made of silver paste.

[0018] A piezoelectric body 30 is disposed on the upper surface of second electrode 22. Piezoelectric body 30 is disposed at a position overlapping substrate 10 in plan view. Piezoelectric body 30 does not overlap first fixed portion 15 or second fixed portion 17 in plan view. Piezoelectric body 30 deforms in accordance with the deformation of substrate 10.

[0019] The material of the piezoelectric body 30 is polyvinylidene fluoride or a chiral polymer. An example of a chiral polymer is polylactic acid (PLA). Polylactic acid is L-type polylactic acid (PLLA) or D-type polylactic acid (PDLA). Polylactic acid made of a chiral polymer has a helical main chain structure. Polylactic acid has piezoelectricity in which the molecules are oriented when uniaxially stretched. Polylactic acid has a piezoelectric constant of d14. The uniaxial stretching direction of polylactic acid is set to form a predetermined angle (for example, approximately 45°±10°) with the Y direction or X direction when viewed in a plane.

[0020] A first electrode 21 is disposed on the upper surface of the piezoelectric body 30. The first electrode 21 is disposed at a position overlapping the substrate 10 in a plan view. The first electrode 21 does not overlap the first fixed portion 15 and the second fixed portion 17 in a plan view. However, in the present invention, the shapes and thicknesses of the first electrode 21, the piezoelectric body 30, and the second electrode 22 are not particularly limited. For example, the first electrode 21, the piezoelectric body 30, and the second electrode 22 may be square or rectangular in a plan view.

[0021] The first electrode 21 is, for example, an inorganic electrode such as ITO (indium tin oxide) or ZnO (zinc oxide), an organic electrode such as PeDOT or conductive polyaniline, a metal film formed by vapor deposition or plating, or a printed electrode film made of silver paste.

[0022] The first electrode 21 and the second electrode 22 are each connected to a controller 90. The controller 90 measures the impedance by measuring the voltage and current generated between the first electrode 21 and the second electrode 22. The controller 90 measures the resonant frequency of the substrate 10 based on the measured impedance.

[0023] FIG. 5 is a schematic diagram showing the vibration of the substrate 10. The hatching in the figure indicates the Z-direction component of the vibration of the substrate 10. When the substrate 10, whose first end 101 and second end 102 have different lengths, vibrates, a Z-direction resonance phenomenon called a flapping mode occurs at multiple locations (three locations in the example of FIG. 5) along the longitudinal direction near the center of the substrate 10 in the longitudinal direction, as shown in FIG. The resonant frequency of the flapping mode changes depending on the amount of deformation of the substrate 10.

[0024] 6 shows the relationship between the bending angle of the substrate 10 in the Z direction and the resonant frequency of the substrate 10 measured by the controller 90. The horizontal axis in FIG. 6 represents the bending angle (deg) of the substrate 10 in the Z direction, and the vertical axis represents the resonant frequency (kHz) of the substrate 10 measured by the controller 90.

[0025] 6, the resonance frequency of the substrate 10 increases linearly as the bending angle of the substrate 10 in the Z direction increases. The resonance frequency does not depend on the sensitivity or noise intensity of the piezoelectric body 30. Therefore, the deformation amount detection device 1 can detect the deformation amount of the substrate 10 in the Z direction with high sensitivity by measuring the resonance frequency with the controller 90. This allows the deformation amount detection device 1 to detect even slight deformation of the detection object 70 in the Z direction with high accuracy.

[0026] Next, Fig. 7 is a plan view showing a modified arrangement of the piezoelectric body 30. As described above, the shape and thickness of the piezoelectric body 30 are not particularly limited in the present invention. The piezoelectric body 30 in the example of Fig. 7 is square in plan view. The piezoelectric body 30 is arranged in the center of the substrate 10 in the Y direction. The piezoelectric body 30 is also arranged near the end of the substrate 10 in the X direction.

[0027] Fig. 8 is a plan view showing another modified example of the arrangement of the piezoelectric body 30. In the example of Fig. 8, the piezoelectric body 30 has a rectangular shape that is long along the Y direction in plan view. The piezoelectric body 30 is arranged at the center of the substrate 10 in the Y direction and on the first end 101 side. The piezoelectric body 30 is also arranged at the center of the substrate 10 in the X direction.

[0028] Even with the arrangements shown in FIGS. 7 and 8, the substrate 10 experiences a Z-direction resonance phenomenon (flapping mode), and the resonance frequency of the flapping mode changes depending on the amount of deformation of the substrate 10.

[0029] Fig. 9(A) is a schematic diagram showing how the substrate 10 vibrates in the arrangement of the piezoelectric body 30 shown in Fig. 7. Fig. 9(B) is a schematic diagram showing how the substrate 10 vibrates when the piezoelectric body 30 is arranged on the first end 101 side of the substrate 10.

[0030] As shown in Figure 9(A), when the piezoelectric body 30 is placed near the center of the substrate 10 in the longitudinal direction, a flapping mode resonance phenomenon occurs in the Z direction at multiple locations (three locations in the example of Figure 9(A)). When the piezoelectric body 30 is placed on the first end 101 side of the substrate 10 as shown in Figure 9(B), complex deformation occurs and the flapping mode resonance phenomenon does not occur.

[0031] Therefore, the piezoelectric body 30 only needs to be disposed at least in the center of the substrate 10 in the longitudinal direction, and the area of ​​the piezoelectric body 30 may be small relative to the substrate 10. In this case, since the area of ​​the piezoelectric body 30 is small, a simpler deformation amount detection device 1 can be realized.

[0032] Next, Fig. 10 is a cross-sectional view of a deformation amount detection device 1 according to Modification 1. Components common to those in the cross-sectional view of Fig. 3 are assigned the same reference numerals, and description thereof will be omitted. The deformation amount detection device 1 shown in Fig. 10 includes a detection piezoelectric element 31 that overlaps the substrate 10 in a planar view and is disposed between a first end 101 and a second end 102, a third electrode 23 that overlaps the detection piezoelectric element 31 in a planar view and is disposed on a first main surface of the detection piezoelectric element 31, and a fourth electrode 24 that overlaps the detection piezoelectric element 31 in a planar view and is disposed on a second main surface of the detection piezoelectric element 31. The piezoelectric element 30 in the deformation amount detection device 1 shown in Fig. 10 is an excitation piezoelectric element.

[0033] The third electrode 23 and the fourth electrode 24 are connected to a controller 90. An AC signal is input from the controller 90 to the first electrode 21 and the second electrode 22, exciting vibration of the piezoelectric body 30. The controller 90 measures the voltage value of the divided voltage generated at the third electrode 23 and the fourth electrode 24. The controller 90 converts the time waveform of the voltage value into a frequency axis and measures the frequency peak of the voltage. The controller 90 regards this frequency peak as the resonant frequency of the substrate 10.

[0034] Like the piezoelectric element 30 serving as the excitation piezoelectric element, the detection piezoelectric element 31 may also be disposed at least in the center of the longitudinal direction of the substrate 10. The relative positions of the detection piezoelectric element 31 and the excitation piezoelectric element 30 are not particularly limited, and they may or may not overlap in plan view.

[0035] 11 shows the relationship between the bending angle of the substrate 10 in the Z direction and the resonant frequency of the substrate 10 measured by the controller 90. The horizontal axis in FIG. 11 represents the bending angle (deg) of the substrate 10 in the Z direction, and the vertical axis represents the resonant frequency (kHz) of the substrate 10 measured by the controller 90.

[0036] 11, the resonant frequency of the substrate 10 increases linearly as the bending angle of the substrate 10 in the Z direction increases. The resonant frequency does not depend on the sensitivity or noise intensity of the piezoelectric element 30. Therefore, the deformation amount detection device 1 can detect the deformation amount of the substrate 10 with high sensitivity by measuring the resonant frequency with the controller 90. Furthermore, since the resonant frequency is found based on measuring the frequency peak of the voltage generated in the detection piezoelectric element 31, it can be measured more simply than measuring using impedance.

[0037] Next, Fig. 12 is a plan view of a deformation amount detection device 1 according to Modification 2. Components common to those in the cross-sectional view of Fig. 2 are given the same reference numerals, and descriptions thereof will be omitted. In the deformation amount detection device 1 shown in Fig. 12, a frame 100 is arranged around the outer periphery of a substrate 10 so as to surround the substrate 10. The substrate 10 is connected to the frame 100 at a first end 101 and a second end 102. Furthermore, both ends of the frame 100 are fixed to the detection object 70 by a first fixing portion 15 and a second fixing portion 17, respectively.

[0038] In the example of FIG. 12, the trapezoidal substrate 10 and the frame 100 are integrally molded, but the substrate 10 and the frame 100 may be formed as separate parts and bonded together.

[0039] Fig. 13 is a schematic diagram showing the vibration of the substrate 10. The hatching in the figure indicates the Z-direction component of the vibration of the substrate 10. As shown in Fig. 13, a flapping mode resonance phenomenon occurs at multiple locations (three locations in the example of Fig. 13) along the longitudinal direction near the center of the substrate 10 in the longitudinal direction. The resonant frequency of the flapping mode changes depending on the amount of deformation of the substrate 10 in the Z direction.

[0040] FIG. 14 shows the relationship between the bending angle of the substrate 10 in the Z direction and the resonant frequency of the substrate 10 measured by the controller 90. The horizontal axis in FIG. 14 represents the bending angle (deg) of the substrate 10 in the Z direction, and the vertical axis represents the resonant frequency (kHz) of the substrate 10 measured by the controller 90. As shown in FIG. 14, the resonant frequency of the substrate 10 increases linearly as the bending angle of the substrate 10 in the Z direction increases. The resonant frequency does not depend on the sensitivity or noise intensity of the piezoelectric element 30. Therefore, the deformation amount detection device 1 can detect the deformation amount of the substrate 10 with high sensitivity by measuring the resonant frequency with the controller 90.

[0041] In the deformation amount detection device 1 of the second modification, the substrate 10 is protected in a frame-like manner by the frame 100, which prevents erroneous reactions due to contact with an external object and allows the deformation amount to be detected with higher accuracy.

[0042] It is preferable that the length of the substrate 10 in the Z direction is shorter (thinner) than the length of the frame 100 in the Z direction. This makes the substrate 10 more susceptible to vibration. Furthermore, since the frame 100 is thicker than the substrate 10, external objects can come into contact with the frame 100, preventing objects from coming into contact with the substrate 10 from above or below, thereby preventing erroneous responses.

[0043] The description of the present embodiment should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined not by the above-described embodiments but by the claims. Furthermore, the scope of the present invention includes the scope equivalent to the claims.

[0044] The technical concept of the present invention can be summarized as follows.

[0045] (1) a substrate having a first end and a second end that are both ends along a first direction, the first end side and the second end side being fixed; a piezoelectric body that overlaps the substrate in a plan view and is disposed between the first end and the second end; a first electrode that overlaps the piezoelectric body in a plan view and is disposed on a first main surface of the piezoelectric body; a second electrode that overlaps the piezoelectric body in a plan view and is disposed on a second main surface of the piezoelectric body; a controller connected to the first electrode and the second electrode; A deformation amount detection device comprising: the substrate has the first end and the second end having different lengths, and resonates in a thickness direction; the controller measures a resonant frequency of the substrate; Deformation detection device.

[0046] (2) The piezoelectric element is disposed at the center of the substrate in the longitudinal direction. The deformation amount detection device according to (1) above.

[0047] (3) The piezoelectric body is an exciting piezoelectric body, The deformation amount detection device is a detecting piezoelectric element that overlaps the substrate in a plan view and is disposed between the first end and the second end; a third electrode that overlaps the detecting piezoelectric body in a plan view and is disposed on a first main surface of the detecting piezoelectric body; a fourth electrode that overlaps the detecting piezoelectric body in a plan view and is disposed on a second main surface of the detecting piezoelectric body; and the third electrode and the fourth electrode are connected to a controller; an AC signal is input to the first electrode and the second electrode; the controller measures the voltages of the third electrode and the fourth electrode to measure the resonant frequency of the substrate; The deformation amount detection device according to (1) or (2) above.

[0048] (4) a frame is disposed around the outer periphery of the substrate; the substrate is connected to the frame at the first end and the second end; Both ends of the frame are fixed to the object to be detected. The deformation amount detection device according to any one of (1) to (3) above.

[0049] (5) The substrate is fixed to the object to be detected at the first end side and the second end side, respectively. The deformation amount detection device according to any one of (1) to (3) above. [Explanation of symbols]

[0050] 1: Deformation detector 10: Substrate 15: 1st fixed part 17:Second fixed part 21: 1st electrode 22: 2nd electrode 23:Third electrode 24: 4th electrode 30: Piezoelectric material 31: Piezoelectric element for detection 70: Object to be detected 90: Controller 100: Frame 101: End 1 102: End 2

Claims

1. a substrate having a first end and a second end that are opposite ends along a first direction, the first end side and the second end side being fixed; a piezoelectric body that overlaps the substrate in a plan view and is disposed between the first end and the second end; a first electrode that overlaps the piezoelectric body in a plan view and is disposed on a first main surface of the piezoelectric body; a second electrode that overlaps the piezoelectric body in a plan view and is disposed on a second main surface of the piezoelectric body; a controller connected to the first electrode and the second electrode; A deformation amount detection device comprising: the substrate has the first end and the second end having different lengths, and resonates in a thickness direction; the controller measures a resonant frequency of the substrate; Deformation detection device.

2. the piezoelectric element is an exciting piezoelectric element, The deformation amount detection device is a detecting piezoelectric element that overlaps the substrate in a plan view and is disposed between the first end and the second end; a third electrode that overlaps the detecting piezoelectric element in a plan view and is disposed on a first main surface of the detecting piezoelectric element; a fourth electrode that overlaps the detecting piezoelectric body in a plan view and is disposed on a second main surface of the detecting piezoelectric body; and the third electrode and the fourth electrode are connected to a controller; an AC signal is input to the first electrode and the second electrode; the controller measures the voltages of the third electrode and the fourth electrode to measure the resonant frequency of the substrate; The deformation amount detection device according to claim 1 .

3. The piezoelectric element is disposed at the center of the substrate in the longitudinal direction. The deformation amount detection device according to claim 1 or 2.

4. a frame is disposed around the outer periphery of the substrate; the substrate is connected to the frame at the first end and the second end; Both ends of the frame are fixed to the object to be detected. The deformation amount detection device according to claim 1 or 2.

5. the substrate is fixed to the detection object at the first end side and the second end side, The deformation amount detection device according to claim 1 or 2.

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