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WO2020066157A1 - Capteur piézolélectrique - Google Patents

Capteur piézolélectrique Download PDF

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Publication number
WO2020066157A1
WO2020066157A1 PCT/JP2019/024100 JP2019024100W WO2020066157A1 WO 2020066157 A1 WO2020066157 A1 WO 2020066157A1 JP 2019024100 W JP2019024100 W JP 2019024100W WO 2020066157 A1 WO2020066157 A1 WO 2020066157A1
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Prior art keywords
piezoelectric
layer
elastic layer
elastic
piezoelectric sensor
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Ceased
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PCT/JP2019/024100
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English (en)
Japanese (ja)
Inventor
吉川　均
泰弘 本荘
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Sumitomo Riko Co Ltd
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Sumitomo Riko Co Ltd
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Publication of WO2020066157A1 publication Critical patent/WO2020066157A1/fr
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/88—Mounts; Supports; Enclosures; Casings

Definitions

  • the present invention relates to a piezoelectric sensor that is flexible and applicable to MEMS.
  • MEMS micro electro mechanical system
  • PZT lead zirconate titanate
  • PVDF polyvinylidene fluoride
  • polylactic acid polylactic acid
  • composites in which piezoelectric particles are filled in a polymer matrix PZT, PVDF, and the like have a large piezoelectric strain constant. For this reason, the charge generated by the applied load increases, and a highly sensitive sensor can be configured.
  • Patent Documents 1 and 2 disclose a biological information measurement panel in which a strain gauge is arranged on a metal or plastic spreadsheet.
  • the biological information measurement panel is used by laying under the body of the subject. For this reason, elastic sheet materials are arranged on both the upper and lower surfaces of the laying board in order to give the examinee a soft feeling.
  • Patent Literature 3 discloses biological information including a plurality of strain-generating plates in which detection units such as strain gauges and piezoelectric elements are arranged and connected in a plane direction, and a rubber base sheet that supports the strain-generating plates. A measuring sensor is described.
  • Patent Literature 4 describes a biological information measurement panel in which a piezoelectric film sensor is sandwiched between two silicone rubber laying plates.
  • the biological information measuring sensors described in Patent Documents 1 to 3 have an elastic rubber sheet material or the like, they have a hard strain plate in addition to a hard strain gauge, and therefore have poor flexibility as a whole. For this reason, when a subject lies on it, it is easy to feel discomfort such as hardness and stiffness.
  • a silicone rubber flooring plate is used instead of a metal strain plate.
  • a piezoelectric sensor is arranged between the two laying boards so as not to overlap with the subject, and distortion of the laying board caused by the living activity of the subject is detected by the piezoelectric sensor. In this case, the vibration generated by the life activity of the subject reaches the piezoelectric sensor through the spreading plate.
  • the slab made of silicone rubber has viscoelasticity, the vibration caused by the living activity of the subject is greatly attenuated before being transmitted to the piezoelectric sensor. For this reason, it is difficult to accurately detect weak vibrations such as breathing and heartbeat.
  • the present invention has been made in view of such circumstances, and it is an object of the present invention to provide a piezoelectric sensor which has a desired sensitivity and is less likely to make a user feel uncomfortable even when touched.
  • a piezoelectric sensor of the present invention has a piezoelectric layer and a pair of electrode layers disposed on both front and back surfaces of the piezoelectric layer, and a plurality of piezoelectric elements disposed apart from each other in the surface direction, An elastic body having an elastic modulus of 10 MPa or less and being disposed on at least one side of the front and back directions of the plurality of piezoelectric elements.
  • the plurality of piezoelectric elements are arranged apart from each other in the surface direction, and an elastic layer having an elastic modulus of 10 MPa or less is arranged on at least one side thereof. Since the piezoelectric element is not continuous in the plane direction and is covered with a relatively flexible elastic layer, even if hard ceramics or resin is used as the piezoelectric layer, these hardly appear, and even when a person comes into contact, the hardness is hard. It is hard to feel discomfort such as pod sensation. Further, compared with the case where one continuous piezoelectric element is arranged in the plane direction, the number of piezoelectric materials used can be reduced, so that the cost can be reduced. Further, since it is possible to fold in the gap between the piezoelectric elements, it is easy to reduce the size.
  • the performance of the sensor according to the usage and the use environment is obtained by selecting a piezoelectric material suitable for the usage and the use environment, such as the dependency on the frequency and the heat resistance, and using the piezoelectric material for the piezoelectric layer.
  • a piezoelectric material suitable for the usage and the use environment such as the dependency on the frequency and the heat resistance
  • the piezoelectric material for the piezoelectric layer be able to.
  • highly accurate detection can be performed even in a weak vibration due to breathing and heartbeat, or in a severe environment such as high temperature and high humidity in a room or a car.
  • FIG. 3 is a sectional view taken along line II-II of FIG. 2. It is a schematic diagram which shows the setting example of a pressure sensitive part.
  • FIG. 2 is a top view of the piezoelectric sensor according to the first embodiment.
  • FIG. 4 is an explanatory diagram of a method for measuring a piezoelectric strain constant.
  • FIG. 1 shows a top view of the piezoelectric sensor of the present embodiment.
  • FIG. 2 is a sectional view taken along line II-II of FIG.
  • the piezoelectric element is shown as transparent. 1 and 2
  • the vertical direction corresponds to the front and back direction of the member, the thickness direction, and the stacking direction, and the front, rear, left, and right directions correspond to the surface direction of the member.
  • the piezoelectric sensor 1 includes two piezoelectric elements 10, a front elastic layer 20, a back elastic layer 30, and a wiring 40.
  • the two piezoelectric elements 10 are interposed between the front elastic layer 20 and the back elastic layer 30.
  • the two piezoelectric elements 10 are juxtaposed at an interval d in the left-right direction.
  • the configuration, shape, and size of the two piezoelectric elements 10 are the same.
  • Each of the two piezoelectric elements 10 has a piezoelectric layer 11 and a pair of electrode layers 12a and 12b.
  • the piezoelectric layer 11 is made of lead zirconate titanate (PZT).
  • the piezoelectric layer 11 has a shape of a square thin plate having a length of 10 mm, a width of 10 mm, and a thickness of 1 mm. The thickness of the piezoelectric layer is about 20% when the thickness of the entire piezoelectric sensor is 100%.
  • the electrode layer 12a is disposed on the entire upper surface of the piezoelectric layer 11, and the electrode layer 12b is disposed on the entire lower surface of the piezoelectric layer 11.
  • Each of the electrode layers 12a and 12b is a 7 ⁇ m-thick silver thin film formed by a baking method.
  • Wirings 40 are connected to both left and right ends of the electrode layer 12a. Similarly, wirings 40 are connected to both left and right ends of the electrode layer 12b.
  • the electrode layers (12a-12a, 12b-12b) of the adjacent piezoelectric elements 10 are electrically connected by the wiring 40.
  • the shortest distance (interval d) between the two piezoelectric elements 10 is 2 mm.
  • the two piezoelectric elements 10 are arranged with an interval longer than the minimum length (1 mm) of the piezoelectric layer 11.
  • a rectangular area including two piezoelectric elements 10 and a gap therebetween defined by connecting the outermost edges of two piezoelectric elements 10 when the piezoelectric sensor 1 is viewed from above. Region
  • the total area ratio of the two piezoelectric elements 10 to the area of the pressure-sensitive portion S is about 91%.
  • the front elastic layer 20 is disposed on the upper surface of the piezoelectric element 10.
  • the front side elastic layer 20 covers the two piezoelectric elements 10 and the gap between them from above.
  • the front elastic layer 20 includes a first elastic layer 21 and a second elastic layer 22 that are stacked in the thickness direction.
  • the first elastic layer 21 is disposed on the piezoelectric element 10 side, that is, on the inside, and the second elastic layer 22 is disposed on the outside.
  • the first elastic layer 21 and the second elastic layer 22 have different elastic moduli.
  • the first elastic layer 21 is made of silicone rubber having a thickness of 1 mm.
  • the elastic modulus of the silicone rubber (first elastic layer 21) is 0.1 MPa.
  • the second elastic layer 22 is made of silicone rubber having a thickness of 1 mm.
  • the elastic modulus of the silicone rubber (second elastic layer 22) is 1.25 MPa.
  • the inner first elastic layer 21 has a smaller elastic modulus than the outer second elastic layer 22.
  • the thickness of the front elastic layer 20 is
  • the back side elastic layer 30 is arranged on the lower surface side of the piezoelectric element 10.
  • the back side elastic layer 30 covers the two piezoelectric elements 10 and the gap between them from below.
  • the back-side elastic layer 30 includes a first elastic layer 31 and a second elastic layer 32 that are stacked in the thickness direction.
  • the first elastic layer 31 is disposed on the piezoelectric element 10 side, that is, on the inner side, and the second elastic layer 32 is disposed on the outer side.
  • the first elastic layer 31 and the second elastic layer 32 have different elastic moduli.
  • the first elastic layer 31 is made of silicone rubber having a thickness of 1 mm.
  • the elastic modulus of the silicone rubber (first elastic layer 31) is 0.1 MPa.
  • the second elastic layer 32 is made of 1 mm thick silicone rubber.
  • the elastic modulus of the silicone rubber (second elastic layer 32) is 1.25 MPa.
  • the inner first elastic layer 31 has a smaller elastic modulus than the outer second elastic layer 32.
  • the thickness of the back side elastic layer 30 is twice the thickness of the piezoelectric layer 11.
  • the total thickness of the front elastic layer 20 and the back elastic layer 30 is four times the thickness of the piezoelectric layer 11.
  • the electrode layers 12a and 12b are electrically connected to a control circuit (not shown) by a wiring 40.
  • a load is applied to the piezoelectric sensor 1
  • electric charges are generated in the piezoelectric layer 11.
  • the generated charge is detected by the control circuit unit as a change in voltage or current.
  • the piezoelectric sensor 1 the two piezoelectric elements 10 are arranged apart from each other in the left-right direction, and on both sides thereof, the two piezoelectric elements 10 and the flexible front elastic layer 20 that continuously covers the gap and the back side are provided.
  • An elastic layer 30 (collectively referred to as elastic layers 20 and 30 in the present embodiment) is disposed.
  • the number of piezoelectric materials used can be reduced, so that the cost can be reduced. Further, since it is possible to fold in the gap between the two piezoelectric elements 10, it is easy to reduce the size.
  • the piezoelectric sensor 1 uses PZT having a relatively large piezoelectric distortion constant, the sensitivity of the sensor is high. Therefore, even a slight vibration due to breathing and heartbeat can be accurately detected.
  • the distance d between the piezoelectric elements 10 is equal to or longer than the thickness (minimum length) of the piezoelectric layer 11.
  • the total thickness of the front elastic layer 20 and the back elastic layer 30 is at least twice the thickness of the piezoelectric layer 11.
  • the thickness of the piezoelectric layer 11 is 33% or less of the total thickness of the piezoelectric sensor 1. These are effective in reducing discomfort.
  • the total area ratio of the two piezoelectric elements 10 to the area of the pressure-sensitive portion S is 80% or more. Thereby, flexibility and sensitivity are compatible.
  • the elastic layers 20 and 30 are each composed of two elastic layers having different elastic moduli.
  • the front-side electrode layer 20 includes a first elastic layer 21 and a second elastic layer 22, and the first elastic layer 21 having a smaller elastic modulus is disposed on the piezoelectric element 10 side.
  • the relatively hard second elastic layer 22 By arranging the relatively hard second elastic layer 22 on the outside in this way, a stimulus can be received over a wide range and the stimulus can be easily transmitted from the flexible first elastic layer 21 to the piezoelectric layer 11. And the sensitivity can be improved.
  • the embodiments of the piezoelectric sensor of the present invention are not limited to the above-described embodiments, and may be implemented in various forms with modifications and improvements that can be made by those skilled in the art without departing from the spirit of the present invention. be able to.
  • the piezoelectric sensor of the present invention includes a plurality of piezoelectric elements and an elastic layer. Hereinafter, each component will be described in detail.
  • the number of piezoelectric elements may be two or more.
  • the shape of the piezoelectric element may be a polygon such as a square, a rectangle, or a rhombus, a circle, an ellipse, or the like, and the size is not particularly limited.
  • the shapes and sizes of the piezoelectric elements need not all be the same.
  • the plurality of piezoelectric elements are spaced apart in a plane direction (a direction substantially perpendicular to the laminating direction of the piezoelectric layer and the electrode layer).
  • the arrangement form may be regular or irregular.
  • the distance between the piezoelectric elements is not particularly limited as long as the piezoelectric sensor can be made flexible enough to reduce uncomfortable feeling even when touched by a person.
  • the shortest distance between the adjacent piezoelectric elements may be adopted.
  • it is desirable that the interval between the piezoelectric elements is equal to or longer than the minimum length of the piezoelectric layer.
  • the minimum length of all the piezoelectric layers may be used as a reference. The intervals between the piezoelectric elements do not need to be the same.
  • the ratio between the piezoelectric element and the gap in the pressure-sensitive portion is not particularly limited. In order to achieve both flexibility and sensitivity, for example, it is desirable that the total area ratio of the piezoelectric element to the area of the pressure-sensitive portion be 80% or more and 98% or less. It is more preferable that the content be 85% or more and 98% or less.
  • the pressure-sensitive portion is a region defined by connecting the outermost edges of the plurality of piezoelectric elements when viewed from the front and back sides of the piezoelectric sensor (the direction in which the constituent members are stacked).
  • FIG. 3 schematically shows a setting example of the pressure sensing unit.
  • FIG. 3 shows an embodiment in which a plurality of piezoelectric elements 100a to 100d having different shapes and sizes are arranged on the upper surface of the elastic layer 200.
  • the outermost edges of the piezoelectric elements 100a to 100d may be connected to set a pressure-sensitive portion S (dotted-line hatched area).
  • Piezoelectric layer The material of the piezoelectric layer is not particularly limited.
  • PZT Lead zirconate titanate
  • BST barium strontium titanate
  • BLT bismuth lanthanum titanate
  • SBT bismuth strontium tantalate
  • KN potassium niobate
  • BT barium titanate
  • potassium sodium niobate Use of piezoelectric ceramics such as (KNN), other ceramics having a perovskite structure and having piezoelectricity, polymers such as polyvinylidene fluoride (PVDF), polylactic acid, and polyurea; Good.
  • PVDF polyvinylidene fluoride
  • electrets of resins such as porous polypropylene, fluororesin, acrylic resin, polyamide, and polyester
  • inorganic electrets such as quartz, quartz, silicon oxide (SiO 2 ), and silicon nitride (SiN) can also be used.
  • the thickness of the piezoelectric layer in one piezoelectric element is 2 mm. It is desirable that: On the other hand, in consideration of durability, the thickness of the piezoelectric layer is preferably 10 ⁇ m or more, and more preferably 20 ⁇ m or more. Further, from the viewpoint of increasing flexibility, the thickness of the piezoelectric layer is preferably 33% or less, more preferably 25% or less of the thickness of the entire piezoelectric sensor.
  • Electrode layer The material of the electrode layer is not particularly limited. Depending on the piezoelectric layer, conductive materials of metals such as silver, gold, copper and nickel, carbon-based conductive materials such as carbon black, carbon nanotubes and thinned graphite, conductive polymers, conductive cloths, conductive materials for polymers May be used. Considering flexibility, ease of production, and cost, a composite in which a conductive material is dispersed in an elastomer such as acrylic rubber, silicone rubber, or urethane rubber is preferable. When the electrode layer is formed from a composite, a conductive paint containing a polymer, a conductive material, or the like may be applied to the substrate or the piezoelectric layer and dried. When the electrode layer is formed from a metal, the electrode layer may be formed by baking or depositing a metal on the piezoelectric layer.
  • the elastic layer is made of an elastic material having an elastic modulus of 10 MPa or less.
  • the elastic modulus of the elastic body is 5 MPa or less, and further 1 MPa or less, the flexibility is further improved.
  • the elastic modulus of the elastic body is preferably set to 0.03 MPa or more, more preferably 0.1 MPa or more, for suppressing the attenuation of the stress.
  • the elastic modulus is calculated from the slope of a linear region of a stress-elongation curve obtained by a tensile test specified in JIS K6251: 2014. The tensile test is performed using a dumbbell-shaped No. 3 test piece (parallel part thickness 5 mm, initial distance between marked lines 20 mm) at a tensile speed of 50 mm / min.
  • the piezoelectric layer is made of a relatively flexible material such as a mixture of an elastomer and piezoelectric particles
  • the elastic layer moves in the plane direction.
  • a shear force acts on the piezoelectric layer.
  • a tensile force in the surface direction is applied to the piezoelectric layer in addition to the pressing force in the front and back directions, and the distortion of the piezoelectric layer increases.
  • the amount of charges generated in the piezoelectric layer increases, and the sensitivity of the sensor improves.
  • the type of the elastic body is not particularly limited.
  • silicone rubber, natural rubber, isoprene rubber, butyl rubber, acrylic rubber, urethane rubber, urea rubber, fluorinated rubber, nitrile rubber, etc. are suitable as the elastomer having a relatively low elastic modulus.
  • silicone rubber or urethane rubber having good affinity with the living body is desirable, and it is desirable that it does not contain a substance extracted over time such as a plasticizer.
  • the Poisson's ratio of the elastomer is approximately 0.5, so that a force applied in the thickness direction acts as a force in the plane direction.
  • the piezoelectric layer is formed of a relatively flexible material such as a mixture of elastomer and piezoelectric particles, the effect of the elastic layer to increase the distortion of the piezoelectric layer is increased, and the sensitivity of the sensor can be improved.
  • the elastic layer is disposed on one or both sides of the front and back directions of the plurality of piezoelectric elements.
  • the elastic layer may be arranged in any manner as long as it covers a plurality of piezoelectric elements. For example, arranging a plurality of piezoelectric elements and a gap between the piezoelectric elements continuously so as to cover the piezoelectric elements is effective in improving the flexibility of the piezoelectric sensor.
  • the elastic layer does not necessarily have to be continuous.
  • the elastic layer may be separately laminated for each piezoelectric element or for every several piezoelectric elements. That is, the laminate of the elastic layer and the piezoelectric element may be arranged in a plane at a predetermined interval.
  • the material of the elastic layer may be the same or different in the plane direction. When the elastic layer is composed of a plurality of layers, the material of each layer may be the same or different.
  • the thickness of the elastic layer may be appropriately determined in consideration of the balance between flexibility and sensitivity. For example, it is desirable that the thickness of the elastic layer be at least twice and at most 10 times the thickness of the piezoelectric layer. When the elastic layers are arranged on both sides of the piezoelectric element, the total thickness thereof may be compared with the thickness of the piezoelectric layer. If the thickness of the elastic layer is too small, desired flexibility cannot be obtained. Conversely, if the thickness of the elastic layer is too large, the sensitivity of the sensor decreases.
  • the thickness of the elastic layer in this specification is the thickness of a portion laminated on the piezoelectric element.
  • the number of elastic layers may be one or two or more.
  • the respective structures may be the same or different.
  • each elastic modulus is set to 10 MPa or less.
  • the elastic layer preferably has a first elastic layer and a second elastic layer that are stacked in the thickness direction and have different elastic moduli. By laminating a plurality of elastic layers having different elastic moduli, it is easy to balance flexibility and sensitivity.
  • the difference in elastic modulus is preferably at least twice. For example, when the one disposed on the piezoelectric element side (inside) is the first elastic layer, the elastic modulus of the first elastic layer is preferably smaller than that of the outer second elastic layer.
  • the sensitivity can be improved while providing flexibility as in the first embodiment.
  • the elastic modulus of the inner first elastic layer is larger than that of the outer second elastic layer, that is, if a more flexible elastic layer is arranged on the outside, the flexibility will be improved, It is effective in reducing discomfort.
  • the wiring connected to the electrode layer may be formed linearly or meandering.
  • the wiring connecting the adjacent piezoelectric elements as a meandering wiring, it is possible to suppress disconnection and a decrease in conductivity when the wiring is bent in a gap between the piezoelectric elements.
  • the piezoelectric sensor of the present invention is used as a biological information sensor for detecting a weak vibration such as respiration or heartbeat, it is desirable that the sensor has high sensitivity.
  • the piezoelectric sensor preferably has a piezoelectric strain constant of 50 pC / N or more.
  • the piezoelectric sensor of the present invention can be manufactured by laminating a piezoelectric element and an elastic layer and pressing them together.
  • an adhesive or the like may be used to bond between the piezoelectric element and the elastic layer, or between the plural elastic layers.
  • the elastic layer is composed of two layers, the material for the inner elastic layer is injected and cross-linked while the piezoelectric element is floated, and the outer elastic layer material is injected and cross-linked to form the elastic body. Layers can be formed. Furthermore, these may be crimped.
  • Example 1 Manufacture of a piezoelectric element
  • An electrode layer is arranged on both sides (both front and back) in the thickness direction of a square thin film-shaped piezoelectric layer, and pressed by using a laminator ("LPD3223" manufactured by Fujipla Co., Ltd.) to form a piezoelectric element Were produced.
  • a laminator (“LPD3223" manufactured by Fujipla Co., Ltd.)
  • LPD3223 manufactured by Fujipla Co., Ltd.
  • As the piezoelectric layer a film made of polyvinylidene fluoride (PVDF) resin “KF Piezo 40 ⁇ m” manufactured by Kureha Corporation was used.
  • the elastic modulus of the PVDF resin film is 3000 MPa.
  • the electrode layer was manufactured as follows.
  • FIG. 4 shows a top view of the piezoelectric sensor according to the first embodiment.
  • the piezoelectric sensor 50 includes an elastic body layer 51 and two piezoelectric elements 52 juxtaposed on the upper surface of the elastic body layer 51.
  • Each of the two piezoelectric elements 52 has a square shape with a side of 20 mm.
  • the distance d between the two piezoelectric elements 52 is 0.5 mm.
  • a rectangular area an area including the two piezoelectric elements 52 and a gap therebetween defined by connecting the outermost edges of the two piezoelectric elements 52 is a pressure-sensitive portion S (the same applies hereinafter)
  • the area occupies the area of the pressure-sensitive portion S.
  • the total area ratio of the two piezoelectric elements 52 is 97.6%.
  • Example 2 (1) Production of Piezoelectric Element A silver electrode layer was formed on both sides (both front and back) in the thickness direction of a rectangular thin piezoelectric layer by a baking method, and two piezoelectric elements were produced. PZT ("C6" manufactured by Fuji Ceramics Co., Ltd.) was used as the piezoelectric layer. The modulus of elasticity of the PZT is 50,000 MPa.
  • Example 3 A piezoelectric sensor was manufactured in the same manner as in Example 2, except that the shape of the piezoelectric layer was changed to a square thin plate (the long side of the rectangle was shortened to 10 mm) and the elastic layer was changed to two layers.
  • the same silicone rubber as that of Example 2 was changed to a thickness of 1 mm as the inner elastic layer disposed on the piezoelectric element side.
  • Silicone rubber (“LIM silicone KE1950-40" manufactured by Shin-Etsu Chemical Co., Ltd., elastic modulus 1.25 MPa, thickness 1 mm) was used as the outer elastic layer disposed outside the inner elastic layer.
  • the outer elastic layer has a rectangular thin plate shape having the same size as the inner elastic layer.
  • Example 4 A piezoelectric sensor was manufactured in the same manner as in Example 3, except that the inner and outer arrangements of the two elastic layers were changed.
  • Example 5 A piezoelectric sensor was manufactured in the same manner as in Example 2, except that the distance between the two piezoelectric elements was changed to 0.5 mm. The total area ratio of the two piezoelectric elements to the area of the pressure-sensitive portion is 97.6%.
  • Example 6 A piezoelectric sensor was manufactured in the same manner as in Example 2 except that the thickness of the elastic layer was changed to 9 mm.
  • Example 1 was the same as Example 1 except that the shape of the piezoelectric layer was changed to a rectangular thin film shape (two sides of the square were lengthened to 40 mm), the number of piezoelectric elements was changed to one, and the material of the elastic layer was changed. Similarly, a piezoelectric sensor was manufactured. Silicone rubber ("LIM Silicone KE1950-20" manufactured by Shin-Etsu Chemical Co., Ltd., modulus of elasticity 0.7 MPa, thickness 1 mm) was used as the elastic layer. Since only one piezoelectric element is provided, in the manufactured piezoelectric sensor, the area of the pressure-sensitive portion is equal to the area of the piezoelectric element. That is, the total area ratio of the piezoelectric element to the area of the pressure-sensitive portion is 100%.
  • Silicone rubber (“LIM Silicone KE1950-20" manufactured by Shin-Etsu Chemical Co., Ltd., modulus of elasticity 0.7 MPa, thickness 1 mm) was used as the elastic layer. Since only one piez
  • FIG. 5 is an explanatory diagram of a method for measuring the piezoelectric strain constant.
  • the reference numerals in FIG. 5 correspond to those in FIG.
  • the piezoelectric sensor 50 was placed on a 12 mm-thick silicone rubber plate 53 with the piezoelectric element 52 facing down.
  • the plus side electrode layer and the minus side electrode layer are each connected to a d33 meter by a wiring (not shown).
  • a disk-shaped bakelite plate 54 (elastic modulus 5 GPa) having a diameter of 20 mm and a thickness of 3 mm was placed on the upper surface of the elastic layer 51 at the center of the two piezoelectric elements 52. Then, as shown by a white arrow in FIG. 5, a load of 4 N was applied from above the bakelite plate 54, and the amount of electric charge generated in the piezoelectric element 52 was measured.
  • the piezoelectric strain constant (pC / N) is calculated by dividing the measured generated electric charge (pC / m 2 ) by the load (N / m 2 ).
  • the piezoelectric strain constant needs to be 20 pC / N or more, and preferably 50 pC / N or more. Therefore, a case where the piezoelectric strain constant is 50 pC / N or more is suitable for respiration and heart rate measurement (indicated by a mark in Table 1 below), and a case where it is 20 pC / N or more and less than 50 pC / N. It was evaluated as possible but slightly inferior in sensitivity (indicated by a triangle in the table).
  • the difference in hardness was obtained by subtracting the hardness of the elastic body layer from the hardness of the piezoelectric sensor.
  • a case where the difference in hardness was less than 8 was evaluated as having no uncomfortable feeling (indicated by a mark “ ⁇ ” in Table 1), and a case where the difference was 8 or more was evaluated as having a sense of incongruity (indicated with “x” in the same table).
  • Table 1 shows the evaluation results together with the configuration of the manufactured piezoelectric sensor, dimensions of each member, and the like.
  • one layer is described as an inner elastic layer.
  • the piezoelectric sensor according to the example in which two piezoelectric elements were arranged had little uncomfortable feeling.
  • the piezoelectric elements were arranged at intervals longer than the minimum length of the piezoelectric layer as in the piezoelectric sensors of Examples 1 to 4, and 6, the effect of reducing the sense of discomfort was high.
  • the piezoelectric sensor of Example 6 when the thickness of the elastic layer was increased, the elastic layer became softer, and the effect of reducing discomfort was large, but the sensitivity was lowered.
  • the decrease in the sensitivity largely depends on the measurement position of the sensitivity.
  • the sensitivity is measured at the center of the two separated piezoelectric elements. For example, if the sensitivity is measured on one of the piezoelectric elements, a higher sensitivity can be obtained. Can be
  • the elastic layer when the elastic layer is composed of two layers having different elastic moduli as in the third and fourth embodiments, the elastic layer improves the sensitivity as compared with the second embodiment while maintaining the flexibility. I was able to. Comparing Example 3 with Example 4, Example 3 in which the elastic layer having a small elastic modulus is arranged on the inner side has higher sensitivity, and Example in which the elastic layer having a smaller elastic modulus is arranged on the outside. In No. 4, the difference in hardness was smaller, and the effect of reducing discomfort was greater.
  • the difference in hardness is 8 despite having an elastic layer having an elastic modulus of 10 MPa or less, and discomfort is felt. occured.
  • the piezoelectric sensor of the present invention is useful as a biological information sensor for measuring a respiratory condition, a heart rate, and the like in the fields of medicine, rehabilitation, nursing care, health care, and training, and in a driver monitoring system that performs vital sensing of an automobile. Further, it is also suitably used for applications of sensors that require flexibility, for example, warning applications for automatic doors of trains, elevators, stores, and the like, and applications for detecting movement of people, objects, and animals on the floor. In addition, in IOT (Internet of Things) home appliances and smart houses, it is suitably used for switches touched by humans, panel sensors, and the like.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)
  • Force Measurement Appropriate To Specific Purposes (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)

Abstract

La présente invention concerne un capteur piézoélectrique (1) comprenant une pluralité d'éléments piézoélectriques (10) qui ont chacun une couche piézoélectrique (11) et une paire de couches d'électrode (12a, 12b) disposées sur les côtés avant et arrière de la couche piézoélectrique (11) et qui sont disposées de manière à être disposées à distance l'une de l'autre dans une direction plane, et une couche de matériau élastique (20, 30) qui comprend un matériau élastique ayant un module d'élasticité de 10 MPa ou moins et est disposé sur au moins un côté de la pluralité d'éléments piézoélectriques (10) dans la direction avant-arrière.
PCT/JP2019/024100 2018-09-27 2019-06-18 Capteur piézolélectrique Ceased WO2020066157A1 (fr)

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JP2018181316A JP7079704B2 (ja) 2018-09-27 2018-09-27 圧電センサ
JP2018-181316 2018-09-27

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JP3144420B1 (ja) 1999-10-21 2001-03-12 オムロン株式会社 人工触覚器およびこの触覚器を用いた人工皮膚ならびにロボット
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JP2011085435A (ja) * 2009-10-14 2011-04-28 Tohoku Univ 触覚センサシステム
JP2013529803A (ja) * 2010-06-11 2013-07-22 スリーエム イノベイティブ プロパティズ カンパニー 力測定を用いるタッチ位置センサ
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JP2015227839A (ja) * 2014-06-02 2015-12-17 株式会社翔栄 フィルムセンサの製造方法、フットセンサ、フィルムセンサ

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115047657A (zh) * 2022-06-27 2022-09-13 绵阳惠科光电科技有限公司 显示面板及其制备方法、显示装置
WO2024001052A1 (fr) * 2022-06-27 2024-01-04 绵阳惠科光电科技有限公司 Écran d'affichage et son procédé d'encapsulation, et appareil d'affichage

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