JP2018036060A - Piezoelectric sensor structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric sensor structure with which it is possible to detect a biological signal (pulse wave, respiration signal, etc.) with high sensitivity and high-speed response, and which can be folded into a compact size when it is stored or transported.SOLUTION: A piezoelectric sensor structure of the present invention comprises: a plurality of vibration receiving plates disposed with a prescribed space therebetween; a piezoelectric sensor structure body including a piezoelectric sheet, and a piezoelectric sensor which has a signal electrode laminated as an integral part on one face of the piezoelectric sheet and a ground electrode laminated as an integral part on the other face of the piezoelectric sheet, and disposed by being bridged over the plurality of vibration receiving plates; and a shield layer disposed on both faces of the piezoelectric sensor structure body. The piezoelectric sensor structure is characterized by being constructed so as to be bent and foldable between the vibration receiving plates.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piezoelectric sensor structure.

   Piezoelectric sheets are materials that are permanently charged by injecting charges into an insulating polymer material. In recent years, piezoelectric sheets have been used for respiration detection, for example. Respiration detection is performed for the purpose of health management by detecting respiration of a patient with apnea syndrome, grasping the situation of a bedridden patient, and grasping the situation during sleep.

  Patent Document 1 describes a vibration sensor, in which a flexible printed circuit board is bent on a piezoelectric film, and a conductor pattern on the inner surface of the bent flexible printed circuit board is applied to both surfaces of the piezoelectric film as electrodes of the piezoelectric film. It is described that the vibration sensor is integrated and integrated, and that the conductor pattern on the outer surface side of the flexible printed circuit board is used as a shield layer.

Japanese Patent No. 5733479 gazette

  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 a biological signal such as a respiratory signal or a pulse wave is low.

  Further, when detecting a biological signal of a person lying on the bed, the piezoelectric sensor is disposed under the mattress. And even if a person lying on the bed rolls over on the bed, the piezoelectric sensor can adjust the width of the bed (bed mat) so that the biological signal of the person lying on the bed can be continuously detected. It is formed in a substantially matching band shape. On the other hand, when the piezoelectric sensor is not used, it is required to be folded into a compact state in order to save 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 compacted during storage or transportation. provide.

The piezoelectric sensor structure of the present invention includes a plurality of vibration receiving plates disposed at predetermined intervals,
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, and stretched over the plurality of vibration receiving plates A piezoelectric sensor structure body having a piezoelectric sensor disposed thereon, and shield layers disposed on both sides of the piezoelectric sensor structure body, and is configured to be bent and folded 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 activity such as breathing and heartbeat of the measurement subject, and the vibrations received by the vibration receiving plate are applied to the 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 formed 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 the plurality of vibration receiving plates are arranged at a predetermined interval, 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. Miniaturization can be achieved.

  A plurality of vibration receiving plates are connected to each other in accordance with the position or shape of the vibration generating source on the piezoelectric sheet structure (for example, a person lying on the bed, a person walking in a passage, or a wall surface of a concrete structure). The vibration generating source is arranged along the shape of the vibration generating source by being relatively displaced, and the piezoelectric sensor disposed on the vibration receiving plate is also deformed along with the arrangement of the vibration receiving plate. It deforms to a state along the shape. 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 formed 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 piezoelectric sensor structure, when the signal electrode and the ground electrode are not integrated with the shield layers disposed on both surfaces of the piezoelectric sensor structure body, a virtual space is provided between the piezoelectric sensor and the shield layer. The capacitance of the electric shield capacitor configured as described above can be reduced, and the piezoelectric sensor can detect the weak vibration generated by the vibration generation source with high sensitivity and at high speed.

  In the piezoelectric sensor of the piezoelectric sensor structure, the signal electrode and / or the ground electrode are 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 weak vibrations generated by the vibration source with high sensitivity and high speed. Can do.

It is the disassembled 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 the disassembled perspective view which showed another example of the piezoelectric sensor. It is the disassembled perspective view which showed another example of the piezoelectric sensor. It is the disassembled perspective view which showed another example of the piezoelectric sensor. It is sectional drawing which showed the piezoelectric sensor structure of this invention. It is the schematic diagram which showed the use condition of the piezoelectric sensor structure of this invention. It is the top view (a) and sectional view (b) which showed other examples of a vibration receiving plate. It is the top view (a) and sectional view (b) which showed other examples 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 generation source is described as an example that the measurement subject P is lying on the bed. However, the vibration generation source is limited to the measurement subject P lying on the bed. is not.

  The piezoelectric sensor structure A has a plurality of vibration receiving plates 1 as shown in FIGS. The vibration receiving plate 1 only needs to be able to receive the load of the person to be measured P. It is preferable that the vibration receiving plate 1 is flexible enough to bend into a shape along the body shape of the measurement subject P by the load of the measurement subject P. As described above, since the vibration receiving plate 1 has the flexibility, the vibration receiving plate 1 is deformed along the body shape of the measurement subject by the load of the measurement subject P, and the deformation of the vibration reception plate 1 is performed. Thus, a piezoelectric sensor 2 (described later) disposed on the vibration receiving plate 1 can also be deformed along the body shape of the person being measured. And the to-be-measured person P is reliably received by the vibration receiving plate 1, and the vibration generated by the biological activity of the to-be-measured person P is reliably received by the piezoelectric sensor 2 and the vibration receiving plate 1, and the piezoelectric sensor 2. Thus, 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. Although the vertical dimension of the vibration receiving plate 1 (the dimension in the height direction of the person P to be measured) depends on the use of the piezoelectric sensor structure, for example, the vertical dimension that can cover the chest of the person P to be measured is preferable. Specifically, 25 to 35 cm is preferable.

  As shown in FIG. 1, the vibration receiving plate 1 has a certain thickness and is formed in a planar rectangular shape. Note that the vibration receiving plate 1 is not limited to a planar 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 disposed 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 in the left-right direction (direction perpendicular to the up-down direction) with a predetermined interval therebetween. As shown in FIG. 1, when three vibration receiving plates 1 are arranged in series, the left and right widths of the center vibration receiving plate 1a are the left and right widths of the vibration receiving plates 1b and 1b located on both sides. It is preferable to be configured to be larger than the above. The person P to be measured has a high probability of being located on the center vibration receiving plate 1a, and the left and right widths of the center vibration receiving plate 1a should be larger than the left and right widths of the vibration receiving plates 1b and 1b located on both sides. Thus, 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 can be more reliably received by the piezoelectric sensor 2 and the vibration receiving plate 1. Thus, the biological signal of the person to be measured P can be detected with higher accuracy.

  The distance between the vibration receiving plates 1 and 1 that are adjacent to each other may be a distance that allows the piezoelectric sensor structure A to 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. When the interval between the vibration receiving plates 1 and 1 adjacent to each other is within the above range, the load of the measurement subject P positioned between the vibration receiving plates 1 and 1 adjacent to each other can be reliably received by the vibration receiving plate 1. it can.

  A piezoelectric sensor structure main body B is configured by arranging strip-shaped flexible piezoelectric sensors 2 on a plurality of vibration receiving plates 1 arranged in series in the left-right direction. The piezoelectric sensor 2 has a left and right length longer than the overall length of the plurality of vibration receiving plates 1 arranged in series and a vertical dimension shorter than the vertical dimension of the vibration receiving plate 1. Yes.

  The band-shaped piezoelectric sensor 2 is arranged in a state where it is stretched over all of the vibration receiving plates (1a, 1b, 1b) arranged in series at the center of the vibration receiving plate 1 in the vertical direction. Yes. The piezoelectric sensor 2 is integrated with 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 stretched over all 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 vibration due to the biological activity of the person to be measured P, and can accurately detect the biological signal of the person to be measured P.

  Further, the vibration due to the biological activity of the person to be measured P is also received by the vibration receiving plate 1, and the vibration receiving plate 1 is vibrated by this vibration, and this vibration is transmitted to the piezoelectric sensor 2. Can be detected.

  As described above, since the piezoelectric sensor 2 can detect the vibration due to the biological activity of the measurement subject P via the vibration receiving plate 1, it is not necessary to increase the area of the piezoelectric sensor 2, and the area is reduced. Can be achieved. 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 by reducing the area of the piezoelectric sensor 2. Therefore, high sensitivity and high speed response of the piezoelectric sensor 2 can be achieved, and the biological signal of the measurement subject P can be detected accurately and quickly.

  The piezoelectric sensor 2 is integrated on the vibration receiving plate 1, while the vibration receiving plate 1 is configured such that the vibration receiving plates 1 and 1 adjacent to each other can be freely displaced relatively. Thus, the vibration receiving plate 1 is relatively displaced along the body shape of the person to be measured P by the load by the person to be measured P, thereby stably supporting the load of the person to be measured P. Further, the piezoelectric sensor 2 integrated on the vibration receiving plate 1 also follows the displacement of the vibration receiving plate 1 and is deformed along the body shape of the person to be measured P. Can be detected with high accuracy.

  The piezoelectric sensor 2 includes 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 in 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 a conductive sheet such as a metal foil and a metal thin film, for example.

  The signal electrode 22 may be formed on the entire surface of the piezoelectric sheet 21, but as shown in FIG. 4, in the state where the notch 22a is formed in the signal electrode 22 and laminated on one surface of the piezoelectric sheet 21, A portion where the signal electrode 22 is not stacked may be formed. As described above, the signal electrode 22 is laminated and integrated only on a part of the piezoelectric sheet 21, so that 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. The piezoelectric sensor 2 can be made small in sensitivity and high-speed response, and the biological signal of the measurement subject P can be detected accurately and quickly.

  Specifically, as the signal electrode 22 in which the notch 22a is formed, for example, a planar rectangle that opens to the short side edge (long side edge) of the planar rectangular body and is long in the long side direction (short side direction) Signal electrode 22 (FIG. 4) formed in a comb-like shape by forming a plurality of cut-out portions 22a in parallel with each other, and one long side edge (short side) of the planar rectangular body facing each other The rectangular rectangular notch 22a1 that opens in the short side direction (long side direction) and the other long side edge (short side edge) that faces each other and the short side direction (long side direction) ) And the long planar rectangular cutouts 22a2 are alternately formed in the long side direction (short side direction) to form a meandering signal electrode 22 (FIG. 5), a planar circular shape, etc. Examples include a signal electrode 22 (FIG. 6) having a plurality of holes.

  In the above description, the case where the notch 22a is formed in the signal electrode 22 has been described. However, even if the notch is formed in the ground electrode 23, a virtual space is formed between the signal electrode and the ground electrode of the piezoelectric sensor 2. Therefore, the capacitance of the capacitor configured in a reduced manner can be reduced, the sensitivity and speed of the piezoelectric sensor 2 can be increased, and the biological signal of the measurement subject P can be detected accurately and quickly.

  Furthermore, flexible exterior sheets 4 and 4 are disposed on both surfaces of the piezoelectric sensor structure body B. The exterior sheet 4 includes a shield layer 41, an electrical insulating sheet 42 laminated and integrated on the outer surface of the shield layer 41, and an adhesive layer 43 stacked and integrated on the inner surface of the shield layer 41. .

  The piezoelectric sensor structure A is affected by electromagnetic noise generated from an electronic device, a communication device, a tap, a power transmission line, and the like in a use environment. The shield layer 41 only needs to 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. Note that the metal thin film may be carried on the electrically insulating sheet 42.

  The electrical 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 (such as a polyethylene layer) that melts when heated to a temperature that does not impair the shield layer 41 and the electrical insulating sheet 42 and exhibits adhesiveness.

  The exterior sheets 4 and 4 disposed on both surfaces of the piezoelectric sensor structure main body B are formed into a bag body by integrating the outer peripheral edge portions of the adhesive layers 43 and 43 facing each other. The piezoelectric sensor structure body A is configured by housing the piezoelectric sensor structure body B.

  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 to the vibration receiving plate 1 are not integrated, a virtual space between the signal electrode 22, the ground electrode 23, and the shield layers 41 and 41 is provided. Therefore, the capacitance of the capacitor constructed can be reduced, the sensitivity and speed of the piezoelectric sensor 2 can be increased, and the biological signal of the measurement 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 by measuring the potential of the signal electrode 22 using the ground electrode 23 as a reference electrode, the living body of the subject P is measured. A 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 differential amplification amount can be reduced. And a high-speed response can be achieved, and a weak biological signal of the measurement subject P can be detected with high sensitivity. Note that the differential input circuit is a circuit that removes unnecessary common mode noise (common-mode noise) included in an input signal input thereto and extracts only a necessary potential signal. That is, the differential input circuit is a circuit that takes out only the differential component of the input signal input thereto and removes the in-phase component.

  In the piezoelectric sensor structure A described above, a plurality of vibration receiving plates 1 are arranged in series at predetermined intervals, and a flexible piezoelectric sensor 2 is provided on the vibration receiving plate 1. The piezoelectric sensor structure main body B is constituted by covering the piezoelectric sensor structure main body B with flexible exterior sheets 4 and 4 from both sides. It can be easily folded by bending, and can be made compact during storage and transportation (see FIG. 7).

  Next, how to use the piezoelectric sensor structure A will be described. The piezoelectric sensor structure A is used by being disposed below the measurement subject P. For example, the piezoelectric sensor structure A can be used to detect a respiratory signal of the measurement subject P lying on the bed. As shown in FIG. 8, the piezoelectric sensor structure A is disposed between the mattress of the bed and the mattress, and is disposed below the chest of the measurement subject P.

  The piezoelectric sensor structure A has a length-wise dimension that substantially matches the width of the bed, and in the state of being arranged between the mattress of the bed C and the mattress, the entire length of the bed C in the width direction. It will be in the state arrange | positioned 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 person P to be measured 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 person P to be measured. Stable support in a state along the body shape of the person P.

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

  Further, in the piezoelectric sensor structure A, the vibration receiving plate 1 receives the vibration due to 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 can detect the biological signal of the person to be measured P. Therefore, the area of the receiving surface of the measurement 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 is highly sensitive to the biological signal of the measurement subject P. Can respond at high speed.

  In the above-described piezoelectric sensor structure A, the case where the vibration receiving plate 1 is a plate having a constant thickness and a flat surface has been described, but is not limited thereto. Specifically, as shown in FIG. 9, the vibration receiving plate 1 may be formed with a plurality of through-holes 1c penetrating between both surfaces at predetermined intervals in the vertical and horizontal directions. In this way, by forming a plurality of through holes 1c in the vibration receiving plate 1, the flexibility of the vibration receiving plate 1 is improved and deformed along the body shape of the subject P due to the load of the subject P. This makes it easier to receive the measurement subject P more stably, and more reliably receives the vibration caused by the biological activity of the measurement subject P. The piezoelectric sensor 2 allows the biological signal of the measurement subject P to be received. It can be detected with higher accuracy.

  Further, as shown in FIG. 10, a plurality of convex portions 1d may be formed on the receiving surface of the measurement subject P in 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 substantially concentrated on the convex portion 1d of the vibration receiving plate 1 and the portion of the piezoelectric sensor 2 mounted on the convex portion 1d. 2, the biological signal of the person to be measured P can be detected with higher accuracy.

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

DESCRIPTION OF SYMBOLS 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 Subject to be measured

Claims (4)

A plurality of vibration receiving plates disposed at predetermined intervals;
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, and stretched over the plurality of vibration receiving plates A piezoelectric sensor structure body having a piezoelectric sensor disposed thereon, and shield layers disposed on both sides of the piezoelectric sensor structure body, and is configured to be bent and folded between the vibration receiving plates. A piezoelectric sensor structure characterized by comprising:   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 disposed on both surfaces of the piezoelectric sensor structure main body are not integrated.   The piezoelectric sensor structure according to any one of claims 1 to 3, wherein the signal electrode and / or the ground electrode is laminated and integrated only on a part of the piezoelectric sheet.

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