JP6775211B2 - Piezoelectric sensor structure - Google Patents

Description

The present invention relates to a piezoelectric sensor structure.

The piezoelectric sheet is a material that is permanently charged inside by injecting an electric charge into an insulating polymer material. In recent years, piezoelectric sheets have been used, for example, for breath detection. Respiratory detection is performed for the purpose of detecting the respiration of a patient with apnea syndrome, grasping the situation of a bedridden patient, and health management by grasping the situation during sleep.

Patent Document 1 describes a vibration sensor, in which a flexible printed substrate is bent from a piezoelectric film, and a conductor pattern on the inner surface of the bent flexible printed substrate is attached to both sides of the piezoelectric film as electrodes of the piezoelectric film. It is described that it is integrated into a vibration sensor, and that the conductor pattern on the outer surface side of the flexible printed substrate is used as a shield layer.

Japanese Patent No. 5733479

However, the vibration sensor disclosed in Patent Document 1 has a problem that the sensitivity is low because the pressure response is low, and the detection accuracy of biological signals such as respiratory signals and pulse waves is low.

Further, in detecting the biological signal of a person lying on the bed, the piezoelectric sensor is arranged under the mattress. The piezoelectric sensor has a width of the bed (mattress) so that even when a person lying on the bed turns over on the bed, the biological signal of the person lying on the bed can be continuously detected. It is formed in a band shape that roughly matches. On the other hand, when the piezoelectric sensor is not used, it is required to be able to be folded into a compact state in order to save space in the storage space.

The present invention provides a piezoelectric sensor structure that can detect weak vibrations such as biological signals (pulse waves, respiration signals, etc.) with high sensitivity and high-speed response, and can be folded and made compact during storage or transportation. provide.

The piezoelectric sensor structure of the present invention includes a plurality of vibration receiving plates arranged at predetermined intervals.
A state in which a piezoelectric sheet, a signal electrode laminated and integrated on one surface of the piezoelectric sheet, and a ground electrode laminated and integrated on the other surface of the piezoelectric sheet are provided and hung on a plurality of vibration receiving plates. It has a piezoelectric sensor structure main body having an arranged piezoelectric sensor, and shield layers arranged on both sides of the piezoelectric sensor structure main body, and is configured to be bendable and foldable between the vibration receiving plates. It is characterized by being.

Since the present invention has the above-described configuration, the vibration receiving plate receives vibrations associated with biological activities such as breathing and heartbeat of the person to be measured, and the vibration received by the vibration receiving plate is used as a piezoelectric sensor. Since it is transmitted and detected by the piezoelectric sensor, it is not necessary to increase the area of the piezoelectric sensor. Therefore, the capacitance of the capacitor virtually configured between the signal electrode and the ground electrode of the piezoelectric sensor can be reduced, and the piezoelectric sensor can detect weak vibration with high sensitivity and high speed. it can.

Since a plurality of vibration receiving plates are arranged at predetermined intervals, the piezoelectric sensor structure can be folded into a compact state by bending between the vibration receiving plates, and can be easily stored and transported. It is possible to reduce the size.

Then, a plurality of vibration receiving plates are attached to each other according to the position or shape of a vibration source (for example, a person lying on a bed, a person walking in a passage, a wall surface of a concrete structure, etc.) on the piezoelectric sheet structure. By being relatively displaced, they are arranged in a state along the shape of the vibration source, and along with the arrangement of the vibration receiving plates, the piezoelectric sensors arranged on these vibration receiving plates are also deformed and the vibration generating sources. It transforms into a state that follows the shape of. Therefore, the piezoelectric sensor can detect the weak vibration generated by the vibration source with high sensitivity and high speed.

In the above piezoelectric sensor structure, when the vertical width of the piezoelectric sensor is smaller than the vertical width of the vibration receiving plate, the capacitance of the capacitor virtually configured between the signal electrode and the ground electrode of the piezoelectric sensor The piezoelectric sensor can detect the weak vibration generated by the vibration source with high sensitivity and high speed.

In the above-mentioned piezoelectric sensor structure, when the signal electrode and the ground electrode and the shield layers arranged on both sides of the piezoelectric sensor structure main body are not integrated, a virtual space is provided between the piezoelectric sensor and the shield layer. The capacitance of the electric shield capacitor configured in the above can be reduced, and the piezoelectric sensor can detect the weak vibration generated by the vibration source with high sensitivity and high speed.

In the piezoelectric sensor of the piezoelectric sensor structure, the signal electrode and / or the ground electrode is laminated and integrated only on a part of the piezoelectric sheet, and when a part of the piezoelectric sheet is exposed, the piezoelectric sensor The capacitance of the capacitor virtually configured between the signal electrode and the ground electrode can be reduced, and the piezoelectric sensor can detect the weak vibration generated by the vibration source with high sensitivity and high speed. Can be done.

It is an exploded perspective view which showed the piezoelectric sensor structure of this invention. It is sectional drawing which showed the piezoelectric sensor structure of this invention. It is sectional drawing which showed the piezoelectric sensor structure of this invention. It is an exploded perspective view which showed another example of a piezoelectric sensor. It is an exploded perspective view which showed another example of a piezoelectric sensor. It is an exploded perspective view which showed another example of a piezoelectric sensor. It is sectional drawing which showed the piezoelectric sensor structure of this invention. It is a schematic diagram which showed the use state of the piezoelectric sensor structure of this invention. It is a plan view (a) and a sectional view (b) which showed another example of a vibration receiving plate. It is a plan view (a) and a sectional view (b) which showed another example of a vibration receiving plate.

An example of the piezoelectric sensor structure of the present invention will be described with reference to the drawings. In the following description, the vibration source will be described as an example of the person P lying down on the bed, but the vibration source is limited to the person P lying down on the bed. is not.

As shown in FIGS. 1 to 3, the piezoelectric sensor structure A has a plurality of vibration receiving plates 1. The vibration receiving plate 1 may be able to receive the load of the person to be measured P. The vibration receiving plate 1 is preferably flexible enough to bend into a shape that conforms to the body shape of the person to be measured P due to the load of the person to be measured P. As described above, since the vibration receiving plate 1 has the above flexibility, the vibration receiving plate 1 is deformed along the body shape of the person to be measured by the load of the person to be measured P, and the vibration receiving plate 1 is deformed. The piezoelectric sensor 2 described later, which is arranged on the vibration receiving plate 1, can also be deformed along the body shape of the person to be measured. Then, the vibration receiving plate 1 reliably receives the measured person P, and the piezoelectric sensor 2 and the vibration receiving plate 1 reliably receive the vibration generated by the biological activity of the measured person P, and the piezoelectric sensor 2 Therefore, the biological signal of the person to be measured P can be detected with high accuracy. The vibration receiving plate 1 is not particularly limited, and examples thereof include a synthetic resin plate such as a polycarbonate plate, a polyolefin plate, a polyester plate, and a polyvinyl chloride plate. The thickness of the vibration receiving plate 1 is preferably 0.1 to 1.0 mm. The vertical dimension of the vibration receiving plate 1 (dimension in the height direction of the subject P) depends on the use of the piezoelectric sensor structure, but for example, the vertical dimension that can cover the chest of the subject P is preferable. 25 to 35 cm is preferable.

As shown in FIG. 1, the vibration receiving plate 1 has a constant thickness and is formed in a planar rectangular shape. The vibration receiving plate 1 is not limited to a flat rectangular shape, and may be, for example, a circular shape or a polygonal shape other than a rectangular shape. An antistatic layer may be formed on the surface of the vibration receiving plate 1 opposite to the surface on which the piezoelectric sensor 2 is arranged to provide an electromagnetic wave shielding effect. The antistatic layer may be formed by applying a known antistatic agent to the surface of the vibration receiving plate 1 and drying it.

The plurality of vibration receiving plates 1 are arranged in series with each other at predetermined intervals in the left-right direction (direction orthogonal to the vertical direction). As shown in FIG. 1, when the three vibration receiving plates 1 are arranged in series, the left-right width of the central vibration receiving plate 1a is the left-right width of the vibration receiving plates 1b and 1b located on both sides. It is preferable that it is configured to be larger than. The person to be measured P has a high probability of being located on the central vibration receiving plate 1a, and the left-right width of the central vibration receiving plate 1a should be larger than the left-right width of the vibration receiving plates 1b and 1b located on both sides. Therefore, the load of the person to be measured P can be stably received, and the vibration generated by the biological activity of the person to be measured P is more reliably received by the piezoelectric sensor 2 and the vibration receiving plate 1, and the piezoelectric sensor 2 Therefore, the biological signal of the person to be measured P can be detected more accurately.

The distance between the vibration receiving plates 1 and 1 adjacent to each other may be such that the piezoelectric sensor structure A can be bent between the vibration receiving plates 1 and 1. The distance between the vibration receiving plates adjacent to each other is preferably 1 to 3 cm. Assuming that the distance between the vibration receiving plates 1 and 1 adjacent to each other is within the above range, the load of the subject P located between the vibration receiving plates 1 and 1 adjacent to each other can be reliably received by the vibration receiving plate 1. it can.

The piezoelectric sensor structure main body B is configured by disposing a band-shaped flexible piezoelectric sensor 2 on a plurality of vibration receiving plates 1 arranged in series in the left-right direction. The piezoelectric sensor 2 has a left-right length longer than the horizontal length of the entire plurality of vibration receiving plates 1 arranged in series, and has a vertical dimension shorter than the vertical dimension of the vibration receiving plate 1. There is.

Then, the strip-shaped piezoelectric sensor 2 is arranged in a state of being hung on all of the vibration receiving plates (1a, 1b, 1b) arranged in series at the central portion in the vertical direction of the vibration receiving plate 1. There is. The piezoelectric sensor 2 is integrated on the upper surface of each vibration receiving plate 1 via a fixing means 3 such as a double-sided adhesive tape.

As described above, the piezoelectric sensor 2 is spread over all of the vibration receiving plates 1 arranged in series, and is supported by the plurality of vibration receiving plates 1 as a whole and stably. Therefore, the piezoelectric sensor 2 can stably detect the vibration caused by the biological activity of the subject P and accurately detect the biological signal of the subject P.

Further, the vibration caused by the biological activity of the subject P is also received by the vibration receiving plate 1, the vibration receiving plate 1 vibrates due to this vibration, and this vibration is transmitted to the piezoelectric sensor 2, and the biological signal of the subject P is transmitted. Can be detected.

As described above, the piezoelectric sensor 2 can detect the vibration caused by the biological activity of the person to be measured P via the vibration receiving plate 1, so that the area of the piezoelectric sensor 2 does not need to be increased and the area is reduced. Can be planned. Then, by narrowing the area of the piezoelectric sensor 2, the capacitance of the capacitor virtually formed between the signal electrode 22 and the ground electrode 23 of the piezoelectric sensor 2 can be reduced. Therefore, it is possible to increase the sensitivity and high-speed response of the piezoelectric sensor 2, and it is possible to accurately and quickly detect the biological signal of the person to be measured P.

The piezoelectric sensor 2 is integrated on the vibration receiving plate 1, while the vibration receiving plates 1 are configured such that the vibration receiving plates 1, 1 adjacent to each other can be freely displaced relative to each other. Therefore, the vibration receiving plate 1 is relatively displaced along the body shape of the person to be measured by the load of the person to be measured P, so that the load of the person to be measured P is stably supported. Further, the piezoelectric sensor 2 integrated on the vibration receiving plate 1 is also deformed to follow the displacement of the vibration receiving plate 1 so as to follow the body shape of the person to be measured P, and the piezoelectric sensor 2 is deformed to the state of the person to be measured P. It is possible to accurately detect the biological signal of.

The piezoelectric sensor 2 has a piezoelectric sheet 21, a signal electrode 22 laminated on one surface of the piezoelectric sheet 21, and a ground electrode 23 laminated on the other surface of the piezoelectric sheet 21. By measuring the potential of the signal electrode 22 using the ground electrode 23 as a reference electrode, the potential generated by the piezoelectric sheet 21 of the piezoelectric sensor 2 can be measured. The piezoelectric sheet 21 is configured by charging a synthetic resin sheet using a general-purpose method. The signal electrode 22 and the ground electrode 23 are formed of, for example, a conductive sheet such as a metal foil and a metal thin film.

The signal electrode 22 may be formed on the entire surface of the piezoelectric sheet 21, but as shown in FIG. 4, the signal electrode 22 has a notch 22a formed in the signal electrode 22 and is laminated on one surface of the piezoelectric sheet 21. A portion where the signal electrodes 22 are not laminated may be formed. By laminating and integrating the signal electrode 22 only on a part of the piezoelectric sheet 21 in this way, the capacitance of the capacitor virtually configured between the signal electrode 22 and the ground electrode 23 of the piezoelectric sensor 2 can be obtained. The size can be reduced to increase the sensitivity and high-speed response of the piezoelectric sensor 2, and the biological signal of the subject P can be detected accurately and quickly.

Specifically, as the signal electrode 22 in which the notch portion 22a is formed, for example, a plane rectangle that opens at the short side edge (long side edge) of a plane rectangular body and is long in the long side direction (short side direction). A signal electrode 22 (FIG. 4) formed in a comb-tooth shape by forming a plurality of notched portions 22a in parallel with each other, and one long side edge (short side) of a plane rectangular body facing each other. A flat rectangular notch 22a1 that opens in the short side direction (long side direction) and opens in the other long side edge (short side edge) facing each other and in the short side direction (long side direction). ), By alternately forming long flat rectangular notches 22a2 in the long side direction (short side direction), the signal electrode 22 (Fig. 5) formed in a serpentine shape, penetrating a flat circular shape, etc. Examples thereof include a signal electrode 22 (FIG. 6) in which a plurality of holes are formed.

In the above, the case where the notch portion 22a is formed in the signal electrode 22 has been described, but even when the notch portion is formed in the ground electrode 23, it is virtual between the signal electrode and the ground electrode of the piezoelectric sensor 2. The capacitance of the capacitor configured to be the same can be reduced, the sensitivity of the piezoelectric sensor 2 can be increased and the response speed can be increased, and the biological signal of the person to be measured P can be detected accurately and quickly.

Further, flexible exterior sheets 4 and 4 are arranged on both sides of the piezoelectric sensor structure main body B. The exterior sheet 4 has a shield layer 41, an electrically insulating sheet 42 laminated and integrated on the outer surface of the shield layer 41, and an adhesive layer 43 laminated and integrated on the inner surface of the shield layer 41. ..

The piezoelectric sensor structure A is affected by electromagnetic noise generated from electronic devices, communication devices, taps, power transmission lines, etc. under the usage environment. The shield layer 41 may shield the piezoelectric sensor 2 from the electromagnetic noise, and examples thereof include a metal foil such as an aluminum foil and a metal thin film. The metal thin film may be supported on the electrically insulating sheet 42.

The electrically insulating sheet 42 is not particularly limited, and examples thereof include a synthetic resin sheet. Examples of the adhesive layer 43 include a synthetic resin layer (polyethylene layer and the like) that melts by heating to a temperature that does not damage the shield layer 41 and the electrically insulating sheet 42 and exhibits adhesiveness.

The exterior sheets 4, 4 arranged on both sides of the piezoelectric sensor structure main body B are formed into a bag by integrating the opposite outer peripheral edges of the adhesive layers 43, 43 into a bag. The piezoelectric sensor structure main body B is housed in the piezoelectric sensor structure A to form the piezoelectric sensor structure A.

The vibration receiving plate 1 is interposed between the piezoelectric sensor 2 and the shield layer 41 of the exterior sheet 4 (4a) on the vibration receiving plate 1 side, and the piezoelectric sensor 2 and the exterior sheet 4a are integrated. Furthermore, since the piezoelectric sensor 2 and the exterior sheet 4 (4b) on the opposite side of the vibration receiving plate 1 are not integrated, it is virtual between the signal electrode 22, the ground electrode 23, and the shield layers 41, 41. The capacitance of the capacitor can be reduced, the sensitivity of the piezoelectric sensor 2 can be increased, and the response speed can be increased, and the biological signal of the subject P can be detected accurately and quickly.

A conductive wire L is electrically connected to the signal electrode 22 and the ground electrode 23 of the piezoelectric sensor 2, and the potential of the signal electrode 22 is measured using the ground electrode 23 as a reference electrode to measure the living body of the person to be measured P. The signal can be detected.

Further, by inputting the output signal of the piezoelectric sheet to the differential input circuit, unnecessary common mode noise (common mode noise) can be removed and the amount of differential amplification can be reduced, so that the sensitivity of the piezoelectric sensor 2 is high. It is possible to achieve high-speed response and to detect a weak biological signal of the subject P with high sensitivity. The differential input circuit is a circuit that removes unnecessary common mode noise (common mode noise) included in the input signal input to the differential input circuit and extracts only the necessary potential signal. That is, the differential input circuit refers to a circuit that extracts only the differential component of the input signal input to the differential input circuit and removes the in-phase component.

Then, in the above-mentioned piezoelectric sensor structure A, a plurality of vibration receiving plates 1 are arranged in series at predetermined intervals, and a flexible piezoelectric sensor 2 is arranged on the vibration receiving plate 1. The piezoelectric sensor structure main body B is formed, and the piezoelectric sensor structure main body B is covered with flexible exterior sheets 4 and 4 from both sides thereof. Therefore, between the vibration receiving plates 1 and 1 adjacent to each other. By bending it, it can be easily folded, and it can be made compact during storage and transportation (see FIG. 7).

Next, the procedure for using the piezoelectric sensor structure A will be described. The piezoelectric sensor structure A is arranged and used below the person to be measured P. For example, the piezoelectric sensor structure A can be used to detect the respiratory signal of the person to be measured P lying on the bed. As shown in FIG. 8, the piezoelectric sensor structure A is arranged between the mattress of the bed and the mattress, and is arranged so as to be located below the chest of the subject P.

The length direction of the piezoelectric sensor structure A substantially matches the width dimension of the bed, and the piezoelectric sensor structure A has a total length in the width direction of the bed C in a state of being arranged between the mattress of the bed C and the mattress. It will be in a state of being arranged over. Therefore, even if the person to be measured P turns over and moves in the width direction of the bed C, the biological signal of the person to be measured P can be reliably detected.

Then, regardless of the position of the subject P lying down in the width direction of the bed C, each of the vibration receiving plates 1 of the piezoelectric sensor structure A is displaced according to the body shape of the subject P to be measured. Stable support for the state along the body shape of person P.

In particular, the piezoelectric sensor structure A has three vibration receiving plates 1, so that the left-right width of the central vibration receiving plate 1a is larger than the left-right width of the vibration receiving plates 1b and 1b located on both sides. In the central part of the bed where the subject P is lying down with the highest probability, the central vibration receiving plate 1a, which is wide on the left and right, stably supports the subject P. On the other hand, at the end of the bed in the width direction, the central vibration receiving plate 1a and the vibration receiving plate 1b of either one of the vibration receiving plates 1b and 1b located on both sides of the subject P The person to be measured P is stably supported by being displaced along the body shape so that the person to be measured P can be stably supported. Therefore, the piezoelectric sensor 2 of the piezoelectric sensor structure A can accurately detect the biological signal of the person to be measured P.

Further, in the piezoelectric sensor structure A, the vibration receiving plate 1 receives the vibration caused by the biological activity of the person to be measured P, and the vibration is transmitted to the piezoelectric sensor 2, so that the piezoelectric sensor 2 receives the biological signal of the person to be measured P. Is configured to be detectable, so that the area of the receiving surface of the subject P in the piezoelectric sensor 2 can be reduced. Therefore, the capacitance of the capacitor virtually formed between the signal electrode 22 and the ground electrode 23 of the piezoelectric sensor 2 can be reduced, and the piezoelectric sensor 2 has high sensitivity to the biological signal of the subject P. Can respond at high speed.

In the above-mentioned piezoelectric sensor structure A, the case where the vibration receiving plate 1 is a plate-like body having a flat surface and a constant thickness has been described, but the present invention is not limited to this. Specifically, as shown in FIG. 9, a plurality of through holes 1c may be formed in the vibration receiving plate 1 so as to penetrate between both sides at predetermined intervals in the vertical and horizontal directions. By forming a plurality of through holes 1c in the vibration receiving plate 1 in this way, the flexibility of the vibration receiving plate 1 is improved, and the vibration receiving plate 1 is deformed along the body shape of the measured person P by the load of the measured person P. It makes it easier to receive the measured person P more stably, and more reliably receives the vibration caused by the biological activity of the measured person P, and the piezoelectric sensor 2 transmits the biological signal of the measured person P. It can be detected more accurately.

Further, as shown in FIG. 10, a plurality of convex portions 1d may be formed on the receiving surface of the person to be measured P on the vibration receiving plate 1 at predetermined intervals in the vertical and horizontal directions. By forming the convex portion 1d on the vibration receiving plate 1, the load of the person to be measured P can be generally concentrated on the convex portion 1d of the vibration receiving plate 1 and the piezoelectric sensor 2 portion mounted on the convex portion 1d, and the piezoelectric sensor can be concentrated. According to 2, the biological signal of the person to be measured P can be detected more accurately.

In the above description, the case where the piezoelectric sensor structure A is used to detect the biological signal of the person to be measured P lying on the bed has been described as an example, but the piezoelectric sensor structure A detects minute vibrations. Since it can respond at high speed with high sensitivity, it can be used for purposes other than detecting the biological signal of the subject P. For example, aging detection by detecting abnormal vibration of infrastructure equipment such as bridges and buildings, various equipment It can also be suitably used for applications such as abnormal vibration detection of rotating devices such as motors used in the above, and suspicious person detection by detecting abnormal vibration in places requiring security.

1 Vibration receiving plate 2 Piezoelectric sensor 3 Fixing means 4 Exterior sheet
21 Piezoelectric sheet
22 Signal electrode
23 Ground electrode
41 Shield layer
42 Electrical insulation sheet
43 Adhesive layer A Piezoelectric sensor structure B Piezoelectric sensor structure body C Bed P Person to be measured

Claims (4)

A plurality of vibration receiving plates arranged at predetermined intervals,
A state in which a piezoelectric sheet, a signal electrode laminated and integrated on one surface of the piezoelectric sheet, and a ground electrode laminated and integrated on the other surface of the piezoelectric sheet are provided and hung on a plurality of vibration receiving plates. It has a piezoelectric sensor structure main body having an arranged piezoelectric sensor, and shield layers arranged on both sides of the piezoelectric sensor structure main body, and is configured to be bendable and foldable between the vibration receiving plates. A piezoelectric sensor structure characterized by being present. The piezoelectric sensor structure according to claim 1, wherein the vertical width of the piezoelectric sensor is smaller than the vertical width of the vibration receiving plate. The piezoelectric sensor structure according to claim 1 or 2, wherein the signal electrode and the ground electrode and the shield layers arranged on both sides of the piezoelectric sensor structure main body are not integrated. The piezoelectric sensor structure according to any one of claims 1 to 3, wherein in the piezoelectric sensor, the signal electrode and / or the ground electrode are laminated and integrated only in a part of the piezoelectric sheet.

Images