JP2021142347A - Piezoelectric sensor structure - Google Patents

Abstract

To provide a piezoelectric sensor structure that can be folded compactly when not in use and measure a biological signal accurately at any place.SOLUTION: A piezoelectric sensor structure includes: a piezoelectric sensor having a piezoelectric sheet, a signal electrode integrally laminated on a first surface of the piezoelectric sheet through a first fixing agent layer, and a ground electrode integrally laminated on a second surface of the piezoelectric sheet through a second fixing agent layer; and a support sheet integrally laminated on a first surface and/or a second surface of the piezoelectric sensor, in which a notch part that reaches the outer surface, and does not reach the inner surface, is formed thereon, which is configured so as to be bent from the notch.SELECTED DRAWING: Figure 1

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 measuring biological signals such as pulse wave signals and respiratory signals.

For example, when measuring the biological signal of a person lying on a bed (hereinafter referred to as "the person to be measured"), a piezoelectric sensor is arranged under the mattress on which the person to be measured lies. The piezoelectric sensor is arranged so as to be located below the chest of the person to be measured, and considering that the person to be measured turns over, the piezoelectric sensor is usually of a length substantially equal to the dimension in the width direction of the bed. It is formed in a strip shape with dimensions.

As described above, since the piezoelectric sensor is formed in a horizontally long strip shape, it is required to be able to be folded into a compact state when not in use.

Patent Document 1 includes a plurality of strain generating plates arranged side by side in the left-right direction of the subject on the lower side of the subject on the bed surface, and each strain generating plate detects the strain of the straining plate of the subject. A biometric information measurement sensor has been proposed in which a detection unit for outputting a signal used for measuring biometric information is provided, and strain generating plates adjacent to each other in the left-right direction are connected via a bendable connecting portion. ..

Japanese Unexamined Patent Publication No. 2012-205803

However, in the biometric information measurement sensor of Patent Document 1, a bendable connecting portion is formed between strain generating plates adjacent to each other, and the connecting portion is configured to be bendable. Therefore, there is a problem that the biological signal of the person to be measured cannot be detected accurately when the person to be measured lies on the connecting portion.

Further, in order to have a foldable structure, it is necessary to divide the sensor into a plurality of parts, which causes a problem that wiring processing and device processing become complicated.

The present invention provides a piezoelectric sensor structure that can be folded compactly when not in use and can accurately measure biological signals and the like at any position.

The piezoelectric sensor structure of the present invention includes a piezoelectric sheet, a signal electrode laminated and integrated on the first surface of the piezoelectric sheet via a first fixing agent layer, and a second fixing agent on the second surface of the piezoelectric sheet. A piezoelectric sensor having a ground electrode laminated and integrated via a layer,
A cut portion is formed by being laminated and integrated on the first surface and / or the second surface of the piezoelectric sensor, and reaches the outer surface and does not reach the inner surface, and is bent at the portion having the cut portion. It is characterized by having a support sheet that is configured as possible.

Since the piezoelectric sensor structure of the present invention has the above-described configuration, the piezoelectric sensor structure can be easily folded while preventing peeling between the piezoelectric sheet and the ground electrode and the signal electrode. ..

Further, the piezoelectric sensor structure facilitates folding of the piezoelectric sensor structure by forming a notch in the support sheet, and a general-purpose piezoelectric sensor can be used at any position. It is possible to measure biological signals with high accuracy.

In the above-mentioned piezoelectric sensor structure, when the support sheet is a foam sheet, even if the uneven portion is formed on the arrangement surface of the piezoelectric sensor structure, the support sheet absorbs the uneven portion of the arrangement surface and is piezoelectric. The sensor structure can be stably arranged at a desired position.

It is sectional drawing which showed the piezoelectric sensor structure of this invention. It is a top view which showed the use state of the piezoelectric sensor structure of this invention. It is a side view which showed the use state of the piezoelectric sensor structure of this invention. It is a perspective view which showed the piezoelectric sensor structure of FIG. It is sectional drawing which showed another example of the piezoelectric sensor structure of this invention. It is sectional drawing which showed the bent state of the piezoelectric sensor structure of FIG. It is sectional drawing which showed another example of the piezoelectric sensor structure of this invention. It is sectional drawing which showed the bent state of the piezoelectric sensor structure of FIG.

An example of the piezoelectric sensor structure of the present invention will be described with reference to the drawings. As shown in FIG. 1, the piezoelectric sensor A has a piezoelectric sheet 1. The piezoelectric sensor structure B is used for measuring a biological signal (pulse wave, respiration signal, body movement, etc.) of a person to be measured, such as a person lying on a bed. For example, the piezoelectric sensor structure B is used by being arranged below the chest of a person (measured person) P lying on the bed, as shown in FIGS. 2 and 3, for example. In order to accurately detect the biological signal of the person to be measured P, it has a vertical dimension (in the height direction of the person to be measured) that can completely cover the chest of the person to be measured. Then, the person to be measured rolls over on the bed and moves in the width direction of the bed (direction orthogonal to the height direction of the person to be measured), so that the piezoelectric sensor structure B substantially matches the width dimension of the bed. The piezoelectric sensor structure B is formed in a strip shape or has a slightly short left-right dimension.

The piezoelectric sheet 1 contains a synthetic resin sheet such as a synthetic resin foamed sheet or a synthetic resin non-foamed sheet, and preferably contains a synthetic resin foamed sheet. The synthetic resin constituting the synthetic resin sheet is not particularly limited, and for example, a polyolefin resin such as a polyethylene resin or a polypropylene resin, a fluorine resin such as polyvinylidene fluoride, a polylactic acid, a liquid crystal resin, or a polytetra. Examples thereof include a laminated sheet of a non-woven fabric made of fluoroethylene or the like, preferably containing a polyolefin-based resin, and more preferably containing a polypropylene-based resin.

The synthetic resin preferably has excellent insulating properties, and the synthetic resin has a volume resistivity value after 1 minute of voltage application at an applied voltage of 500 V in accordance with JIS K6911 (hereinafter, simply referred to as "volume resistivity value"). ) Is 1.0 × 10 ¹⁰ Ω · m or more, preferably a synthetic resin.

^{The volume resistivity value of the synthetic resin is preferably 1.0 × 10 12} Ω · m or more, more preferably 1.0 × 10 ¹⁴ Ω · m or more, because the piezoelectric sheet has more excellent piezoelectricity.

Examples of the polyethylene-based resin include an ethylene homopolymer or a copolymer of ethylene containing an ethylene component in an amount of more than 50% by mass and at least one α-olefin having 3 to 20 carbon atoms. .. Examples of the ethylene homopolymer include low-density polyethylene (LDPE) radically polymerized under high pressure, medium-low pressure high-density polyethylene (HDPE) polymerized at medium and low pressure in the presence of a catalyst, and the like. Linear low density polyethylene (LLDPE) can be obtained by copolymerizing ethylene and α-olefin, and the α-olefins include propylene, 1-butene, 1-pentene, 1-hexene and 4-methyl-. Examples thereof include 1-pentene, 1-octene, 1-nonene, 1-decene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like, and α-olefins having 4 to 10 carbon atoms are preferable. The content of α-olefin in the linear low-density polyethylene is usually 1 to 15% by mass.

The polypropylene-based resin is not particularly limited as long as it contains a propylene component in an amount of more than 50% by mass, and for example, it has 20 carbon atoms other than propylene homopolymer, propylene and at least one kind of propylene. Examples thereof include copolymers with the following olefins. The polypropylene-based resin may be used alone or in combination of two or more. Further, the copolymer of propylene and an olefin having 20 or less carbon atoms other than at least one kind of propylene may be either a block copolymer or a random copolymer.

Examples of the α-olefin copolymerized with propylene include ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, and the like. Examples thereof include 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosen.

The foaming ratio of the synthetic resin foamed sheet is preferably 3 to 15 times, more preferably 4 to 10 times. When the foaming ratio of the synthetic resin foamed sheet is 3 times or more, the piezoelectricity of the piezoelectric sheet is improved. When the foaming ratio of the synthetic resin foamed sheet is 15 times or less, the mechanical strength of the piezoelectric sensor is improved, or the piezoelectric sensor maintains excellent piezoelectricity over time, which is preferable. The expansion ratio of the synthetic resin foam sheet is a value obtained by dividing the density of the entire synthetic resin constituting the synthetic resin foam sheet by the density of the synthetic resin foam sheet.

The thickness of the synthetic resin foam sheet is preferably 10 to 300 μm, more preferably 30 to 200 μm. When the thickness of the synthetic resin foam sheet is 10 μm or more, the mechanical strength of the piezoelectric sensor is improved, which is preferable. When the thickness of the synthetic resin foam sheet is 300 μm or less, the output power of the piezoelectric sensor is stable and the accuracy of the piezoelectricity of the piezoelectric sensor is improved.

The piezoelectric sheet 1 is configured by charging the synthetic resin sheet. The method of charging the synthetic resin sheet is not particularly limited, and examples thereof include a method of applying a direct current electric field to the synthetic resin sheet.

The method of applying a DC electric field to the synthetic resin sheet is not particularly limited. For example, (1) a flat plate electrode in which the synthetic resin sheet is sandwiched between a pair of flat plate electrodes and is in contact with the surface to be charged is used as a high-pressure DC power supply. A method of connecting and grounding the other plate electrode and applying a high DC or pulsed high voltage to the synthetic resin sheet to inject an electric charge into the synthetic resin to charge the synthetic resin sheet, (2) No. 1 of the synthetic resin sheet. A needle-shaped electrode or wire electrode that is electrically connected to a DC high-pressure power supply with a grounded flat plate electrode superposed on one surface and with a predetermined interval on the second surface side of the synthetic resin sheet. Is arranged, a corona discharge is generated by electric charge concentration near the tip of the needle-shaped electrode or the surface of the wire electrode, air molecules are ionized, and air ions generated by the polarity of the needle-shaped electrode or the wire electrode are repelled. A method of charging the synthetic resin sheet and the like can be mentioned.

The signal electrode 2 is laminated and integrated on the first surface of the piezoelectric sheet 1 via the first fixing agent layer 4, and the ground electrode is laminated on the second surface of the piezoelectric sheet 1 via the second fixing agent layer 5. 3 are laminated and integrated to form the piezoelectric sensor A. Then, by measuring the potential of the signal electrode 2 using the ground electrode 3 as a reference electrode, the potential generated by the piezoelectric sheet 1 of the piezoelectric sensor A can be measured. Although FIG. 1 shows a case where the signal electrode 2 and the ground electrode 3 are completely laminated on the surface of the piezoelectric sheet 1, they may be partially laminated on the surface of the piezoelectric sheet 1. ..

Specifically, the signal electrode 2 is formed on the first synthetic resin sheet 6, and the first synthetic resin sheet 6 is arranged so that the signal electrode 2 is on the piezoelectric sheet 1 side. Is laminated and integrated on the first surface of the piezoelectric sheet 1 by the first fixing agent layer 4.

The ground electrode 3 is formed on the second synthetic resin sheet 7, so that the ground electrode 3 is on the piezoelectric sheet 1 side of the second synthetic resin sheet 7, and the second synthetic resin sheet 7 is used as the second fixing agent. The layer 5 is laminated and integrated on the second surface of the piezoelectric sheet 1.

The fixing agent constituting the first fixing agent layer and the second fixing agent layer is composed of a reaction-based, solvent-based, water-based, or hot-melt-based adhesive or adhesive, and maintains the sensitivity of the piezoelectric sheet 1. From the viewpoint of the above, a fixing agent having a low dielectric constant is preferable. Examples of the fixing agents 4 and 5 include an acrylic pressure-sensitive adhesive, and specific examples thereof include an acrylic pressure-sensitive adhesive commercially available from Sekisui Chemical Co., Ltd. under the trade name “WT # 5405A”.

A support sheet 8 is laminated and integrated on the first surface of the piezoelectric sensor A. When the piezoelectric sensor structure B is arranged on a desired arrangement surface, the support sheet 8 can be stably arranged on the arrangement surface without the piezoelectric sensor A being unexpectedly bent or deformed. It is provided in. The support sheet 8 may be laminated and integrated on the second surface of the piezoelectric sensor A, but in the following, when the support sheet 8 is laminated and integrated on the first surface of the piezoelectric sensor A. Will be described as an example.

The method of laminating and integrating the support sheet 8 on the piezoelectric sensor A is not particularly limited, but it is preferable to use a double-sided adhesive tape from the viewpoint of workability. As the double-sided adhesive tape, a double-sided adhesive tape commercially available from Sekisui Chemical Co., Ltd. under the trade name "570E" can be used.

The piezoelectric sensor A has flexibility that allows it to be bent at a desired position in the left-right direction and folded in the left-right direction. Similarly, the support sheet 8 has flexibility that allows it to be bent at a desired position in the left-right direction and folded in the left-right direction.

As described above, the support sheet 8 may have flexibility so that it can be folded from a desired position, but it is preferable that the support sheet 8 is elastically deformable. When the support sheet 8 is elastically deformable in this way, the support sheet 8 is elastically deformable even if the uneven portion is formed on the arrangement surface on which the piezoelectric sensor structure B is arranged. As a result, the uneven portion is absorbed to exert the non-landing adjustment function, and the piezoelectric sensor configuration B can be stably arranged in a state in which the piezoelectric sensor A is suitable for measuring the biological signal of the person to be measured.

When the support sheet 8 is elastically deformable, the 50% compressive strength of the support sheet 8 is preferably 30 to 600 kPa, more preferably 50 to 500 kPa, and particularly preferably 50 to 400 kPa. When the elastic modulus of the support sheet 8 is within the above range, the support sheet 8 exhibits an excellent non-land adjustment function. The 50% compressive strength of the support sheet is a value measured in accordance with JIS K6767.

Examples of the support sheet 8 include a synthetic resin non-foamed sheet and a synthetic resin foamed sheet, and a synthetic resin foamed sheet is preferable. As the synthetic resin foam sheet, the same one as the synthetic resin foam sheet used as the raw material of the piezoelectric sheet 1 can be used.

The support sheet 8 is formed with a plurality of notches 81 parallel to each other at desired intervals in the left-right direction. The cut portion 81 is formed in a direction orthogonal to the folding direction (horizontal direction) of the piezoelectric sensor structure B (vertical direction). The cut portion 81 is formed by cutting from the first surface 8a of the support sheet 8 toward the vicinity of the piezoelectric sheet 1. The cut portion 81 reaches the first surface 8a of the support sheet 8, but does not reach the second surface 8b of the support sheet 8. The depth of the cut portion 81 is preferably 60 to 99%, more preferably 70 to 98%, and particularly preferably 80 to 95% of the thickness of the support sheet 8. When the depth of the cut portion 81 is within the above range, the piezoelectric sensor A is composed of the signal electrode or the ground electrode and the piezoelectric sheet, as described later, without impairing the mechanical strength of the support sheet 8. It can be easily folded without causing peeling from 1.

The thickness of the support sheet is preferably 1 to 20 mm, more preferably 2 to 10 mm, and particularly preferably 3 to 7 mm. When the thickness of the support sheet is within the above range, the piezoelectric sensor A can be easily folded without causing peeling between the signal electrode or the ground electrode constituting the piezoelectric sensor A and the piezoelectric sheet 1 as described later. Can be done.

In addition, in FIG. 4, a plurality of cut portions 81 are formed in parallel with each other at a predetermined interval to form a cut portion group 81A, and between the cut portions 81 adjacent to each other in the cut portion group 81A. Although the case where one or more other notch groups 81A are formed with an interval larger than the interval of the above is described, a plurality of notch portions 81 may be formed at equal intervals. , A plurality of notches 81 may be formed at irregular intervals. The number of cut portions 81 in the cut portion group 81A may be the same, or an arbitrary number of cut portions 81 may be included in each cut portion group 81A.

The notch 81 of the support sheet 8 is preferably formed over the entire length of the support sheet 8 in the vertical direction. Since the cut portion 81 is formed in the above-described form, when the support sheet 8 is bent, the divided pieces 80 between the cut portions 81 can be made independent of each other. As a result, as will be described later, the occurrence of wrinkles on the second surface 8b of the support sheet 8 is largely prevented. Further, when the support sheet 8 is elastically reconstructably deformable, the divided pieces 80 of the support sheet 8 are elastically and reconstructively deformed independently of each other, thereby forming on the arrangement surface of the piezoelectric sensor structure B. Each of the divided pieces 80 of the uneven portion is appropriately deformed according to the shape and size of the uneven portion, and the piezoelectric sensor structure B can be stably arranged on the arrangement surface in a desired state.

In addition, in FIG. 1, the case where the cut portion 81 of the support sheet 8 is formed by being cut by the cutting blade is shown, but as shown in FIG. 5, a part is cut out and the cut space is formed. Part 82 may be formed. Examples of the cut space portion 82 include a V-shaped cross section and a rectangular cross section, and a V-shaped cross section is preferable.

As shown in FIG. 6, when the piezoelectric sensor structure B is bent in the left-right direction at a predetermined position in the left-right direction so that the support sheet 8 is on the outside, the first surface 8a of the support sheet 8 is stretched. , The second surface 8b of the support sheet 8 is contracted. When the notch 81 is not formed in the support sheet 8, the second surface of the support sheet is contracted and wrinkles are generated on the surface. The thicker the support sheet 8, the larger the difference between the radius of curvature of the first surface of the support sheet and the radius of curvature of the second surface of the support sheet, and the second surface of the support sheet and the portion in the vicinity thereof become larger. It is shrunk more and the wrinkles on the second surface of the support sheet are also larger. As described above, when wrinkles are generated on the second surface of the support sheet, the piezoelectric sensor laminated on the second surface also causes similar wrinkles along with the wrinkles formed on the second surface. When the piezoelectric sensor is wrinkled, a portion that is pulled outward of the bent portion and a portion that is pulled inward of the bent portion are generated, and shear stress and peeling stress are applied to the first fixing agent layer and the second fixing agent layer. In addition, as a result, an unexpected situation occurs in which the signal electrode and the ground electrode are partially separated from the surface of the piezoelectric sheet.

Therefore, in the piezoelectric sensor structure B, a cut portion 81 is formed in the support sheet 8 at a portion (bent portion) that is bent when the piezoelectric sensor structure B is folded. At the bent portion of the piezoelectric sensor structure B at the time of folding, a cut portion 81 is formed in the support sheet 8, and the outer portion 8c in which the cut portion 81 of the support sheet 8 is formed is divided into a plurality of pieces and supported. No contraction force is applied to the second surface 8b of the sheet 8. Then, in the state where the piezoelectric sensor structure B is folded, in the inner portion 8d of the support sheet 8 where the cut portion 81 is not formed, the virtual outer surface 8e shown in FIG. 6 when the piezoelectric sensor structure B is folded. The difference between the radius of curvature and the radius of curvature of the second surface 8b is made as small as possible, the shrinkage of the second surface 8b of the support sheet 8 is suppressed as much as possible, and the occurrence of wrinkles on the second surface 8b is generally suppressed. doing. Therefore, when the piezoelectric sensor structure B is folded from a desired position, the second surface 8b of the support sheet 8 forms a smooth arcuate surface, and the piezoelectric sensor A also has a smooth arcuate shape along the arcuate surface. No stress is applied to the piezoelectric sensor A to separate the piezoelectric sheet 1 from the signal electrode 2 or the ground electrode 3.

Since the piezoelectric sensor structure B has a notch 81 formed in the support sheet 8 as described above, the piezoelectric sheet 1 is separated from the signal electrode 2 or the ground electrode 3 even when folded. Can be folded compactly without causing

In the above-mentioned piezoelectric sensor structure B, the case where the support sheet is laminated and integrated on the first surface or the second surface of the piezoelectric sensor A has been described, but the first surface and the second surface of the piezoelectric sensor A have been described. Support sheets 8 and 8'may be laminated and integrated on both surfaces. The support sheet 8'that is laminated and integrated on the second surface of the piezoelectric sensor A and the notch 81'formed in the support sheet 8'are the support sheets that are laminated and integrated on the first surface of the piezoelectric sensor A. Since the configuration is the same as that of the notch 81 formed in the 8 and the support sheet 8, the description thereof will be omitted.

When the support sheets 8 and 8'are laminated and integrated on both the first surface and the second surface of the piezoelectric sensor A, for example, the piezoelectric sensor structure B is folded with the first surface facing outward. At that time, as shown in FIG. 7, the support sheet 8'laminated and integrated on the second surface of the piezoelectric sensor A prevents the piezoelectric sensor A from being excessively bent, and the piezoelectric sheet 1 of the piezoelectric sensor A and the piezoelectric sheet 1 The peeling between the signal electrode 2 and the ground electrode 3 can be effectively prevented.

A Piezoelectric sensor B Piezoelectric sensor structure 1 Piezoelectric sheet 2 Signal electrode 2 Signal electrode 3 Ground electrode 4 Fixing agent layer 5 Fixing agent layer 6 Synthetic resin sheet 7 Synthetic resin sheet 8 Support sheet 8 Support sheet
81 Notch
81A Notch Group

Claims (7)

The piezoelectric sheet, the signal electrode laminated and integrated on the first surface of the piezoelectric sheet via the first fixing agent layer, and the second surface of the piezoelectric sheet laminated and integrated via the second fixing agent layer. piezoelectric sensors (except piezoelectric sensor which is divided into a plurality.) that can be folded and possess a ground electrode and,
A cut portion is formed by being laminated and integrated on the first surface and / or the second surface of the piezoelectric sensor and reaches the outer surface and does not reach the inner surface, and is bent at the portion having the cut portion. the piezoelectric sensor structure, characterized in that it comprises enabling-configured and a support sheet. The piezoelectric sensor structure according to claim 1, wherein the piezoelectric sheet is a synthetic resin foamed sheet. The piezoelectric sensor structure according to claim 2, wherein the synthetic resin constituting the synthetic resin foam sheet is a polyolefin resin. The piezoelectric sensor structure according to any one of claims 1 to 3, wherein the support sheet is elastically deformable. The piezoelectric sensor structure according to any one of claims 1 to 4, wherein the support sheet is a foam sheet. The piezoelectric sensor structure according to any one of claims 1 to 5, wherein the cut portion is formed in a direction orthogonal to the folding direction of the piezoelectric sensor structure. The piezoelectric sheet, the signal electrode laminated and integrated on the first surface of the piezoelectric sheet via the first fixing agent layer, and the second surface of the piezoelectric sheet were laminated and integrated via the second fixing agent layer. Piezoelectric sensors that have a ground electrode and can be folded (excluding piezoelectric sensors that are divided into a plurality of parts),
A cut portion is formed by being laminated and integrated on the first surface and / or the second surface of the piezoelectric sensor, and reaches the outer surface and does not reach the inner surface, and is bent at the portion having the cut portion. A method of using a piezoelectric sensor structure, which comprises folding a piezoelectric sensor structure that comprises a support sheet that is configured to be possible.

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