WO2023223879A1

WO2023223879A1 - Deformation amount detection device

Info

Publication number: WO2023223879A1
Application number: PCT/JP2023/017364
Authority: WO
Inventors: 佳郎田實; 健山本; 隼宝田; 健一森; 正道安藤
Original assignee: 株式会社村田製作所; 学校法人関西大学
Priority date: 2022-05-19
Filing date: 2023-05-09
Publication date: 2023-11-23

Abstract

A deformation amount detection device (1) comprises: a substrate (10) that has a first end and a second end which are two ends in a first direction, and that is fixed at the first end side and the second end side; a piezoelectric body (30) that overlaps the substrate (10) in a plan view and that is disposed between the first end and the second end; an input electrode (21) that overlaps the piezoelectric body (30) in a plan view and that inputs an input signal to the piezoelectric body (30); an output electrode (22) that overlaps the piezoelectric body (30) in a plan view and that outputs an output signal from the piezoelectric body (30); and a controller that inputs the input signal to the input electrode (21) and receives the output signal from the output electrode (22). The substrate (10) is provided with a slit (50) between the first end and the second end. The output electrode (22) is disposed at a position so as to overlap the slit (50) in a plan view. The piezoelectric body (30) resonates in the thickness direction of the piezoelectric body (30).

Description

Deformation amount detection device

The present invention relates to a deformation amount detection device.

Patent Document 1 discloses a deformation detection device that includes a first electrode, a second electrode, and a flexible transmission section.

In the configuration of Patent Document 1, an elastic wave is generated when an input signal is input to the first electrode. The transmission section transmits the elastic wave to the second electrode. The second electrode generates an output signal using an elastic wave. With the configuration of Patent Document 1, the amount of deformation of the transmission section from the reference state can be detected based on the output signal.

International Publication No. 2022/030356

An object of an embodiment of the present invention is to provide a deformation amount detection device that detects deformation amount with high sensitivity using resonance in the thickness direction.

A deformation amount detection device according to an embodiment of the present invention has a first end and a second end that are both ends along a first direction, and a substrate to which the first end side and the second end side are fixed. , a piezoelectric body that overlaps the substrate in plan view and is disposed between the first end and the second end; and an input electrode that overlaps the piezoelectric body in plan view and inputs an input signal to the piezoelectric body. an output electrode that overlaps the piezoelectric body in plan view and outputs an output signal from the piezoelectric body; and a controller that inputs an input signal to the input electrode and receives the output signal from the output electrode. In the deformation detection device, the substrate is provided with a slit between the first end and the second end, and the output electrode is disposed at a position overlapping the slit in plan view, The piezoelectric body resonates in the thickness direction of the piezoelectric body.

The substrate and the piezoelectric body tend to vibrate in the thickness direction due to the slits provided in the substrate. Since the output electrode is arranged at a position overlapping the slit in plan view, it is arranged at a position of the piezoelectric body where the amount of deformation is the largest. Therefore, the deformation amount detection device can detect the deformation amount with high sensitivity using resonance in the thickness direction.

According to an embodiment of the present invention, the amount of deformation can be detected with high sensitivity using resonance in the thickness direction.

FIG. 2 is a perspective view of the deformation amount detection device 1. FIG. 2 is a cross-sectional view taken along line II shown in FIG. 1. FIG. 2 is a cross-sectional view taken along line II shown in FIG. 1. FIG. FIG. 2 is a plan view of the deformation amount detection device 1. FIG. 5(A) and 5(B) are schematic diagrams showing the vibration mode of the piezoelectric body 30, and FIG. 5(C) is a sectional view taken along the line II-II shown in FIG. 5(B). . 3 is a diagram showing the relationship between the bending angle of the substrate 10 and the resonance frequency of the piezoelectric body 30. FIG. FIG. 3 is a diagram showing frequency characteristics of an output signal. FIG. 3 is a diagram showing the relationship between the bending angle of the substrate 10 and the output signal. FIGS. 9(A) and 9(B) are schematic diagrams showing how the deformation amount detection device 1 is fixed to a detection target 70 that may undergo minute deformation. FIGS. 10(A) and 10(B) are schematic diagrams showing how the deformation amount detection device 1 is fixed to a detection target 70 that may undergo minute deformation. 7 is a schematic diagram showing a vibration mode of a piezoelectric body 30 according to Modification 1. FIG. 7 is a diagram showing the relationship between the bending angle of the substrate 10 and the resonant frequency of the piezoelectric body 30 according to Modification 1. FIG. 7 is a diagram showing the relationship between the bending angle of the substrate 10 and the output signal according to Modification 1. FIG.

FIG. 1 is an external perspective view of the deformation amount detection device 1. 2 and 3 are cross-sectional views taken along line II shown in FIG. 1. FIG. 4 is a plan view of the deformation amount detection device 1.

The deformation detection device 1 includes a substrate 10 , a first fixing section 15 , a second fixing section 17 , a piezoelectric body 30 , an input electrode 21 , an output electrode 22 , a reference electrode 25 , and a controller 90 .

The substrate 10 is made of, for example, PET, polycarbonate (PC), acrylic (PMMA), stainless steel, aluminum alloy, copper alloy, or the like. The substrate 10 has a first end 101 and a second end 102, which are both ends along the first direction. The lower surface of the substrate 10 on the first end 101 side is fixed to the detection target 70 by the first fixing part 15 . The lower surface of the substrate 10 on the second end 102 side is fixed to the detection target 70 by the second fixing part 17 . The first fixing part 15 and the second fixing part 17 are, for example, adhesive tapes.

In the following description, the first direction, which is the length 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 width direction of the substrate 10, which is orthogonal to the Y direction when viewed from above, is defined as the Y direction. is defined as the X direction.

The deformation amount detection device 1 detects the amount of deformation of the flexible substrate 10 from its reference state. In this embodiment, the deformation amount detection device 1 detects the angle θ when the substrate 10 is bent along the Y direction, as shown in FIG.

A reference electrode 25 is arranged on the upper surface of the substrate 10. The reference electrode 25 is arranged at a position overlapping the substrate 10 when viewed from above. The reference electrode 25 has the same area as the substrate 10 in plan view. However, the reference electrode 25 may be arranged only at a position overlapping the input electrode 21 and the output electrode 22 in plan view. The reference electrode 25 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 formed from silver paste.

A piezoelectric body 30 is arranged on the upper surface of the reference electrode 25. The piezoelectric body 30 is arranged at a position overlapping the substrate 10 when viewed from above. The piezoelectric body 30 has the same area as the substrate 10 in plan view. The piezoelectric body 30 deforms as the substrate 10 deforms.

The material of the piezoelectric body 30 is polyvinylidene fluoride or chiral polymer. The chiral polymer is, for example, polylactic acid (PLA). Polylactic acid is L-type polylactic acid (PLLA) or D-type polylactic acid (PDLA). Polylactic acid consisting of a chiral polymer has a main chain having a helical structure. Polylactic acid has piezoelectricity in which molecules are oriented by being 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, about 45°±10°) with the Y direction or the X direction when viewed from above.

The substrate 10 is provided with a slit 50. The slit 50 is provided between the first end 101 and the second end 102 in plan view. In this embodiment, the slit 50 is arranged at the center of the substrate 10 in the Y direction (dotted line shown in FIGS. 3 and 4). The center of the substrate 10 in the Y direction coincides with the bending center line of the substrate 10. The slits 50 make it easier for the substrate 10 and the piezoelectric body 30 to vibrate in the thickness direction. Note that in this embodiment, the slit 50 has a rectangular shape that is long in the Y direction when viewed from above, but the shape of the slit 50 when viewed from above is not particularly limited. The slit 50 may have a square, diamond, circular, oval, or other shape, for example.

An input electrode 21 and an output electrode 22 are arranged on the upper surface of the piezoelectric body 30. The input electrode 21 and the output electrode 22 are arranged at positions overlapping the substrate 10 when viewed from above. The input electrode 21 and the output electrode 22 are arranged at positions that do not overlap the first fixing part 15 and the second fixing part 17 in plan view. The input electrode 21 is arranged on the side closer to the first end 101 than the center of the substrate 10 in the Y direction (the dotted line shown in FIGS. 3 and 4). The output electrode 22 is arranged at a position overlapping the slit 50 when viewed from above. In this embodiment, the output electrode 22 is arranged at the center of the substrate 10 in the Y direction (dotted line shown in FIGS. 3 and 4). That is, the output electrode 22 is arranged at the position of the piezoelectric body 30 where the amount of deformation is the largest.

The input electrode 21 and the output electrode 22 are, 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 formed by silver paste. It is a membrane.

The input electrode 21 and the output electrode 22 are each connected to a controller 90. Controller 90 inputs an input signal to input electrode 21 and receives an output signal from output electrode 22 . The input electrode 21 inputs an input signal whose voltage changes periodically to the piezoelectric body 30. The piezoelectric body 30 vibrates in response to an input signal. The output electrode 22 outputs an output signal generated by the vibration of the piezoelectric body 30.

FIGS. 5(A) and 5(B) are schematic diagrams showing how the piezoelectric body 30 vibrates. FIG. 5(C) is a cross-sectional view taken along line II-II shown in FIG. 5(B). The piezoelectric body 30 resonates in the thickness direction of the piezoelectric body 30. Specifically, when a sinusoidal input signal is input from the input electrode 21, the piezoelectric body 30 has a resonance mode standing along the Y direction as shown in FIG. 5(A), and a resonance mode as shown in FIGS. As shown in FIG. 5(C), the resonance mode is located at the center of the Y direction along the X direction. In the following description, the resonance mode that exists along the Y direction will be referred to as resonance mode A, and the resonance mode that will exist along the X direction will be referred to as resonance mode B.

FIG. 6 shows the relationship between the bending angle of the substrate 10 and the resonance frequency of the piezoelectric body 30. The horizontal axis shown in FIG. 6 is the bending angle (°) of the substrate 10, and the vertical axis is the resonant frequency (Hz) of the piezoelectric body 30.

As shown in FIG. 6, the resonance of the piezoelectric body 30 has multiple resonance modes. A1 shown in FIG. 6 indicates the first-order resonance mode among the resonance modes A. A2 indicates a secondary resonance mode among the resonance modes A. A3 indicates a third-order resonance mode among the resonance modes A. B1 indicates a first-order resonance mode among resonance modes B. B2 indicates a secondary resonance mode among the resonance modes B.

For example, the controller 90 inputs a sine wave input signal with an amplitude of 5 V while sweeping the frequency. The controller 90 measures the resonance frequency of each of the plurality of resonance modes.

In the standard state (bending angle 0°), the piezoelectric body 30 exhibits resonance frequencies at approximately 70 Hz and approximately 330 Hz. The resonant frequency of 70 Hz corresponds to the primary resonant mode A1 of the resonant modes A. The frequency of 330 Hz corresponds to the secondary resonance mode A2 of the resonance mode A. As the bending angle of the substrate 10 increases, the resonance frequency of the primary resonance mode A1 increases in accordance with the bending angle of the substrate 10. When the bending angle of the substrate 10 becomes 2 degrees and the resonant frequency reaches approximately 290 Hz, the resonant frequency of the primary resonant mode A1 does not change. However, when the bending angle of the substrate 10 becomes 2 degrees or more, the resonance frequency of the secondary resonance mode A2 increases in accordance with the bending angle of the substrate 10. When the bending angle of the substrate 10 becomes 3 degrees and the resonant frequency reaches approximately 570 Hz, the resonant frequency of the secondary resonant mode A2 does not change. However, when the bending angle of the substrate 10 becomes 3 degrees or more, the resonance frequency of the tertiary resonance mode A3 increases in accordance with the bending angle of the substrate 10.

FIG. 7 is a diagram showing the frequency characteristics of the output signal. The horizontal axis shown in FIG. 7 is frequency (Hz), and the vertical axis is voltage (mV). The example in FIG. 7 shows the frequency characteristics of the output signal obtained from the output electrode 22 when the controller 90 inputs an input signal of 5 V voltage to the input electrode 21 and changes the bending angle of the substrate 10. It is a graph.

The example in FIG. 7 shows the frequency characteristics of the output signal when the bending angle of the substrate 10 is changed from 4.2° to 5.0° in 0.2° increments. As shown in FIG. 7, it can be seen that the resonant frequency corresponding to the resonant mode A changes toward a higher frequency depending on the bending angle of the substrate 10. Further, it can be seen that the resonant frequency corresponding to the resonant mode B also changes to the high frequency side according to the bending angle of the substrate 10.

Therefore, the controller 90 sweeps the frequency of the input signal and detects the bending angle of the substrate 10 according to the value of the detected resonance frequency. For example, when the controller 90 detects a resonance frequency of 150 Hz, the controller 90 detects the bending angle of the substrate 10 as 1 degree.

On the other hand, when the first resonance frequency of the first resonance mode among the plurality of resonance modes exceeds a predetermined value, the controller 90 detects the bending angle according to the value of the second resonance frequency of the second resonance mode. For example, when the first resonance frequency of the first resonance mode A1, which is the first resonance mode, exceeds 290 Hz, the controller 90 controls the controller 90 according to the value of the second resonance frequency of the second resonance mode A2, which is the second resonance mode. Detects bending angle. Alternatively, if the second resonance frequency of the second resonance mode A2, which is the second resonance mode, exceeds 570 Hz, the controller 90 controls the controller 90 according to the value of the third resonance frequency of the third resonance mode A3, which is the third resonance mode. Detects bending angle. Alternatively, when the first resonance frequency of the first resonance mode B1, which is the first resonance mode, exceeds 900 Hz, the controller 90 controls the controller 90 according to the value of the second resonance frequency of the second resonance mode B2, which is the second resonance mode. Detects bending angle.

As described above, by changing the resonance mode of the resonance frequency associated with the bending angle, the controller 90 can accurately detect the bending angle of the substrate 10 according to the value of the resonance frequency.

Next, FIG. 8 shows the relationship between the bending angle of the substrate 10 and the output signal. The horizontal axis shown in FIG. 8 is the bending angle (°) of the substrate 10, and the vertical axis is the voltage (mV) of the output signal.

In this example, the controller 90 applies a sinusoidal input signal of a certain fixed frequency to the input electrode 21. Controller 90 receives the output signal from output electrode 22 and measures the voltage.

As shown in FIG. 8, for example, when a sine wave input signal with a first frequency of 53 Hz is applied to the input electrode 21, a voltage of about 10 mV is measured when the substrate 10 is in the reference state (bending angle 0°). In the example of FIG. 8, it can be seen that when the bending angle of the substrate 10 is increased, the measured voltage drops rapidly.

Further, as shown in FIG. 8, for example, when a sine wave input signal with a second frequency of 430 Hz is applied to the input electrode 21, a voltage of about 10 mV is measured when the substrate 10 is bent at an angle of 2.2°. In the example of FIG. 8, it can be seen that when the bending angle of the substrate 10 is made smaller or larger than 2.2 degrees, the measured voltage drops rapidly.

Therefore, the controller 90 detects the bending angle of the substrate 10 according to the magnitude of the output signal when an input signal of a constant frequency such as 53 Hz or 430 Hz is input. Thereby, the controller 90 can detect minute bending angles with high precision.

FIGS. 9(A) and 9(B) are schematic diagrams showing how the substrate 10 of the deformation amount detection device 1 is attached and fixed to the detection target 70. The detection target 70 in this example is a battery. Batteries may swell slightly over a long period of time, from several months to several years, and may undergo slight deformation. It is difficult for general sensors to detect such minute deformations that occur over a long period of time.

On the other hand, as shown in FIG. 9(B), in this embodiment, when the detection object 70, which is a battery, swells, the substrate 10 of the deformation amount detection device 1 bends in accordance with the deformation of the detection object 70. Since the deformation of the detection target 70 due to the bulge is very small, the bending angle of the substrate 10 is also very small. However, as shown in FIG. 8, the controller 90 applies a sine wave input signal of, for example, 53 Hz to the input electrode 21 and measures the voltage of the output signal, thereby allowing a very small bending angle from the reference state. Can be detected. Therefore, the deformation amount detection device 1 can detect a slight bulge in the detection target object 70, which is a battery.

Next, FIGS. 10(A) and 10(B) are schematic diagrams showing how the substrate 10 of the deformation amount detection device 1 is attached and fixed to the detection target 70. The detection target 70 in this example is also a battery.

In this example, the substrate 10 of the deformation amount detection device 1 is attached to the detection target 70 with the holding member 900 bent at a predetermined angle (for example, 2.2°).

As shown in FIG. 8, the controller 90 can detect a very small bending angle by applying, for example, a 430 Hz sine wave input signal to the input electrode 21 and measuring the voltage of the output signal. Therefore, also in this case, the deformation amount detection device 1 can detect a slight bulge in the detection target object 70, which is a battery.

FIG. 11 is a schematic diagram showing the vibration mode of the piezoelectric body 30 according to the first modification. FIG. 12 shows the relationship between the bending angle of the substrate 10 and the resonance frequency of the piezoelectric body 30 according to Modification 1. FIG. 13 shows the relationship between the bending angle of the substrate 10 and the output signal according to Modification 1.

The deformation amount detection device according to Modification 1 has the same configuration as the configuration shown in FIG. However, the material of the piezoelectric body 30 is polylactic acid. The uniaxial stretching direction of polylactic acid is set to form the same angle (for example, about 0°±10°) as the Y direction or the X direction when viewed from above.

FIG. 11 shows the vibration mode when a sine wave with an amplitude of 5 V is applied to the input electrode 21 of the deformation amount detection device 1. As shown in FIG. 11, when the uniaxial stretching direction of polylactic acid is at the same angle as the Y direction or the X direction in plan view, when a sinusoidal input signal is input to the input electrode 21, the piezoelectric body 30 mainly becomes a resonance mode that vibrates in the plane direction.

In the resonance mode, as shown in FIG. 12, the resonance frequency increases as the bending angle of the substrate 10 increases. Therefore, the controller 90 can accurately detect the bending angle by measuring the resonance frequency.

Furthermore, in the resonance mode, as shown in FIG. 13, the output voltage decreases as the bending angle of the substrate 10 increases. Therefore, the controller 90 can detect an accurate bending angle by measuring the output voltage with respect to the input of a sine wave of a certain fixed frequency.

The description of this embodiment is illustrative in all respects, and should be considered not to be restrictive. The scope of the invention is indicated by the claims rather than the embodiments described above. Furthermore, the scope of the present invention includes a range equivalent to the claims.

1: Deformation detection device 10: Substrate 15: First fixed part 17: Second fixed part 21: Input electrode 22: Output electrode 25: Reference electrode 30: Piezoelectric body 50: Slit 70: Detection target 90: Controller 101: First end 102: Second end 900: Holding member

Claims

A substrate having a first end and a second end that are both ends along the first direction, and the first end side and the second end side are fixed;
a piezoelectric body that overlaps the substrate in plan view and is disposed between the first end and the second end;
an input electrode that overlaps the piezoelectric body in plan view and inputs an input signal to the piezoelectric body;
an output electrode that overlaps the piezoelectric body in plan view and outputs an output signal from the piezoelectric body;
a controller that inputs the input signal to the input electrode and receives the output signal from the output electrode;
A deformation amount detection device comprising:
The substrate is provided with a slit between the first end and the second end,
The output electrode is arranged at a position overlapping the slit in plan view,
The piezoelectric body resonates in a thickness direction of the piezoelectric body,
Deformation amount detection device.
The resonance has a plurality of resonance modes,
The controller measures the resonance frequency of each of the plurality of resonance modes,
detecting a bending angle of the substrate according to the value of the resonant frequency;
Sweeping the frequency of the input signal;
If the first resonance frequency of the first resonance mode among the plurality of resonance modes exceeds a predetermined value, detecting the bending angle according to the value of the second resonance frequency of the second resonance mode.
The deformation amount detection device according to claim 1.
The controller receives an input signal of a first frequency;
detecting the bending angle of the substrate according to the magnitude of the output signal;
The deformation amount detection device according to claim 1.
The substrate is attached to a detection target,
The deformation amount detection device according to claim 3.
The controller receives an input signal of a second frequency;
detecting the bending angle of the substrate according to the magnitude of the output signal;
The substrate is attached to the detection target while being bent at a predetermined angle via a holding member.
The deformation amount detection device according to claim 1.
The piezoelectric body contains polylactic acid,
The uniaxial stretching direction of the polylactic acid forms the same angle as the first direction or a direction perpendicular to the first direction,
The controller receives a sine wave input signal,
detecting the bending angle of the substrate according to the magnitude of the output signal;
The deformation amount detection device according to claim 1.