WO2010010502A1 - Transducteur piézoélectrique de torsion - Google Patents

Transducteur piézoélectrique de torsion Download PDF

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Publication number
WO2010010502A1
WO2010010502A1 PCT/IB2009/053127 IB2009053127W WO2010010502A1 WO 2010010502 A1 WO2010010502 A1 WO 2010010502A1 IB 2009053127 W IB2009053127 W IB 2009053127W WO 2010010502 A1 WO2010010502 A1 WO 2010010502A1
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WO
WIPO (PCT)
Prior art keywords
electrode
piezoelectric transducer
piezoelectric
longitudinal axis
elastic element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2009/053127
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English (en)
Inventor
Giorgio De Cicco
Bruno Morten
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Universita Degli Studi di Modena e Reggio Emilia
Original Assignee
Universita Degli Studi di Modena e Reggio Emilia
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Universita Degli Studi di Modena e Reggio Emilia filed Critical Universita Degli Studi di Modena e Reggio Emilia
Publication of WO2010010502A1 publication Critical patent/WO2010010502A1/fr
Anticipated expiration legal-status Critical
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Classifications

    • 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
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • 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
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H10N30/208—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using shear or torsion displacement, e.g. d15 type devices

Definitions

  • the invention relates to a piezoelectric transducer, in particular a torsional piezoelectric transducer that is usable both as a torsional piezoelectric actuator and as a torsional piezoelectric sensor.
  • piezoelectric transducers are increasingly used, i.e. sensors or actuators that are intelligent, i.e. that are able to adapt to various operating conditions.
  • piezoelectric transducers are widely used that are able to convert mechanical energy into electric energy and vice versa, inasmuch as the reduced dimensions and lightness thereof can be integrated into various structures to be monitored to make an intelligent system.
  • the piezoelectric transducers are easily and preferably made of piezoelectric laminas, which consist of metal laminas associated with piezoelectric elements.
  • the electromechanical coupling in the piezoelectric laminas enables the piezoelectric laminas to be used both as sensors and as actuators.
  • a deformation of the piezoelectric lamina induces a potential difference between the electrodes associated with the piezoelectric element, thus making the lamina act as a sensor.
  • applying a potential difference between the electrodes of the piezoelectric element induces in the latter a deformation that causes deformation of the entire lamina, thus making the lamina operate as an actuator.
  • torsional transducers are increasingly required that are able to cause or detect torsional deformation around a torsion axis.
  • the object of this invention is to carry out a piezoelectric torsional transducer that is simple and cheap to make.
  • a torsional piezoelectric transducer comprising a lamina- shaped substratum, characterised in that at least a layer of piezoelectric material is associated with a side of said substratum, said layer being operationally associated with at least a first and a second electrode that are electrically insulated from one another, each of said first electrode and second electrode being provided with a plurality of electrode elements that are parallel to one another, said electrode elements that are parallel to one another defining at least an arrangement of interdigitated electrode elements extending in a tilted direction with respect to a longitudinal axis of said substratum.
  • the transducer according to the invention can be applied to an elastic structure in which a torsion must be induced.
  • the elastic structure is lamina-shaped, applying a transducer according to the invention on both faces of the lamina, it is possible to obtain a pure torsion deformation owing to the tilted arrangement of the interdigitated elements of the electrodes, associated with the layer of piezoelectric material.
  • each piezoelectric transducer generates a torsion stress and a blending stress of the lamina.
  • the torsion stresses generated by the transducers arranged on opposite sides of the lamina are summed together, whilst the blending stresses are mutually cancelled so as to obtain a pure torsion stress.
  • the elastic structure has a prismatic shape, to obtain a pure torsion deformation it is sufficient to apply the transducer according to the invention to alternating sides of the prismatic shape or to all sides of said prismatic shape .
  • the tilt of the interdigitated elements is preferably 45° with respect to a longitudinal axis of the substratum, to obtain maximum efficiency in making axial torsion.
  • the electrodes associated with each layer of piezoelectric material are further preferably embedded in the piezoelectric material. In this manner efficient conversion of the electric energy into mechanical energy or vice versa is possible. In other words, if it is used as an actuator, the piezoelectric material will be excited not only locally at the elements constituting each electrode but in all the mass thereof; vice versa, if it is used as a sensor, the elements constituting each electrode will detect with great sensibility mechanical stress applied to the mass of the piezoelectric material .
  • said at least an arrangement of interdigitated elements comprises a first arrangement of interdigitated elements extending in a first direction and a second arrangement of interdigitated elements extending in a second direction, said first direction and said second direction forming together a 90° angle.
  • This configuration of the electrodes enables, at the resonance frequency of the elastic structure, to which the transducer according to the invention is applied, a high spectral definition axial torsion to be achieved inasmuch as the lamina is brought to torsion at a frequency, and therefore at an a priori wavelength, that corresponds to the main harmonic of the induced spectral component.
  • said at least an arrangement of interdigitated elements comprises a first arrangement of interdigitated elements extending in a first direction, a second arrangement of interdigitated elements extending in a second direction and a third arrangement of interdigitated elements extending in a third direction, said first direction and said second direction forming together a 90° angle, said third direction being parallel to said first direction.
  • Figure 1 is a schematic top view of a first embodiment of a transducer according to the invention.
  • Figure 2 is a schematic top view of a second embodiment of a transducer according to the invention.
  • Figure 3 is a schematic top view of a third embodiment of a transducer according to the invention.
  • Figure 4 is a schematic top view that illustrates the application of transducers according to the invention to a lamina- shaped elastic structure;
  • Figure 5 is a side section view of the elastic structure in
  • Figure 4 Figure 6 is a side view like that in Figure 5, that illustrates a version of application of transducers according to the invention to a lamina-shaped elastic structure;
  • Figure 7 is a side section view like that in Figure 5, that illustrates a further version of application of transducers according to the invention to a lamina- shaped elastic structure .
  • a torsional transducer 1 comprises a lamina- shaped substratum 2, typically consisting of alumina, or of another flexible elastic material that resists high temperatures.
  • a layer 7 of piezoelectric material is deposited that is associated with a first electrode 8 and with a second electrode 9.
  • the first electrode 8 and the second electrode 9, that are electrically insulated from one another, are supplied by respective supply means by respective contacts 10 and 11, which supply a suitable voltage V, as will be disclosed below, to initialise the piezoelectric material or alternatively maintain the piezoelectric material in an operational torsional condition.
  • FIG. 1 there is illustrated a first embodiment of the torsional transducer 1.
  • the first electrode 8 and the second electrode 9 define an arrangement 17 of interdigitated elements extending in a direction tilted by 45° with respect to a longitudinal axis A of the transducer 1.
  • the first electrode 8 has a plurality of elongated rectilinear elements 12, of different length, that are parallel to one another, arranged at the same distance from one another, which are tilted with respect to the longitudinal axis A of the transducer 1.
  • the second electrode 9 has a plurality of elongated rectilinear elements 14, of different length, that are parallel to one another, arranged at the same distance from one another, which are tilted by 45° with respect to the longitudinal axis A of the transducer 1.
  • the parallel elements 12 of the first electrode 8 and the parallel elements 14 of the second electrode 9 are parallel to one another and are arranged in a comb- like way, that is they are interdigitated. In this manner all the interdigitated elements 12 and 14 define an arrangement 17 of interdigitated electrode elements extending in a direction tilted by 45° with respect to the longitudinal axis A of the transducer 1.
  • the arrangement 17 of interdigitated electrode elements is enclosed in a rectangle 18 that has a longitudinal extent in a direction parallel to said longitudinal axis A such extent being chosen on the basis of the operating frequency at which the torsional transducer according to the invention operates.
  • the length of the side of the rectangle 18 parallel to said axis A is chosen equal to ⁇ /4, where 1/ ⁇ is proportional to the resonance frequency F of the elastic structure to which the transducer 1 is applied.
  • Figure 2 there is illustrated a second embodiment of a transducer 1 according to the invention.
  • the first electrode 8 comprises a rectilinear portion 8a that extends parallel to the longitudinal axis A of the transducer 1 and a plurality of elongated rectilinear elements 12, of different length, that are parallel to one another, arranged at the same distance from one another, which are tilted with respect to the longitudinal axis of the lamina by 45°.
  • the first electrode 8 further comprises a plurality of elongated rectilinear elements 13, of different length, that are parallel to one another, arranged at the same distance from one another, which are tilted with respect to said longitudinal axis A by 135° . It should be noted that the rectilinear elements 12 tilted by 45° are joined to the rectilinear elements 13 tilted to 135° by the rectilinear portion 8a, to constitute the electrode 8.
  • the second electrode 9 has a rectilinear portion 9a that extends parallel to said longitudinal axis A and a plurality of elongated rectilinear elements 14, of different length, that are parallel to one another, arranged at the same distance from one another, which are tilted by 45° with respect to the longitudinal axis A.
  • the second electrode 9 further has a plurality of elongated rectilinear elements 15, of different length, that are parallel to one another, arranged at the same distance from one another, which are tilted with respect to the longitudinal axis A. It should be noted that the rectilinear elements 14 tilted by 45° are joined to the rectilinear elements 15 tilted to 135° by the rectilinear portion 9a and by a central portion 16 that is perpendicular to the rectilinear portion 9a to constitute the electrode 9.
  • the parallel elements 12 of the first electrode 8 and the parallel elements 14 of the second electrode 9 are parallel to one another and are arranged in a comb- like way, that is they are interdigitated. In this manner all the interdigitated elements 12 and 14 define a first arrangement 17 of electrode elements extending in a direction tilted by 45° with respect to the longitudinal axis A.
  • the first arrangement 17 of interdigitated electrode elements is enclosed in a first rectangle 18 that has a longitudinal extent in a direction parallel to said longitudinal axis A such extent being chosen on the basis of the operating frequency at which _the torsional transducer 1 according to the invention operates.
  • the length of the first rectangle 18 parallel to said longitudinal axis A is chosen equal to ⁇ /4, where 1/ ⁇ is proportional to the resonance frequency F of the elastic structure to which the transducer 1 is applied.
  • the parallel elements 13 of the first electrode 8 and the parallel elements 15 of the second electrode 9 are parallel to one another and are arranged in a comb- like way, that is they are interdigitated. In this manner all the interdigitated elements 13 and 15 define a second arrangement 19 of interdigitated electrode elements extending in a direction tilted by 135° with respect to the longitudinal axis A.
  • the second arrangement 19 of interdigitated electrode elements is enclosed in a second rectangle 20, defined by the perpendicular portion 16 of the electrode 9 as far as the end portions of the electrodes 8 and 9, which has the same longitudinal extent as the first rectangle 18, equal to ⁇ /4. It should be noted that by placing the first arrangement 17 of interdigitated electrode elements and the second arrangement 19 of interdigitated electrode elements alongside one another the first electrode 8 and the second electrode 9 extend for a total longitudinal length equal to ⁇ /2.
  • FIG 3 there is illustrated a third embodiment of a torsional transducer 1 according to the invention.
  • the first electrode 8 and the second electrode 9 define a first arrangement 17 of interdigitated electrode elements enclosed in a first rectangle 18, a second arrangement 19 of interdigitated electrode elements enclosed in a second rectangle 20 and lastly a third arrangement 21 of interdigitated electrode elements enclosed in a third rectangle 22.
  • the first arrangement 17 extends in a direction tilted by 45° with respect to the longitudinal axis A of the transducer
  • the second arrangement 19 extends in a direction tilted by 135° with respect to the longitudinal axis A of the transducer
  • the third arrangement 21 extends in a direction tilted by 45° with respect to the longitudinal axis A of the transducer.
  • Both the first and the second and the third rectangle 18, 20, 22 have a greater side the dimension of which is equal to ⁇ /4.
  • the electrodes 8, 9 may comprise any number of arrangements of interdigitated electrodes, the tilt of which is alternatively 45° and 135°.
  • Figures 4 and 5 there is illustrated a first example of application of torsional transducers 1 according to the invention to a lamina-shaped elastic element 3, provided with faces 3a and 3b that are opposite one another, to make, for example, an actuator or a torsional sensor.
  • a torsional transducer 1 according to the invention is applied to each face of the lamina- shaped elastic element 3 .
  • Each transducer 1 is arranged so that the longitudinal axis A of the transducer 1 is parallel to the longitudinal axis B of the lamina-shaped elastic element 3.
  • the torsional transducer 1 according to the invention can be applied to the respective face 3a, 3b of the lamina- shaped elastic element 3 by gluing the substratum 2 to the face 3a, 3b.
  • the torsional transducer 1 can be made directly on the respective face 3a, 3b of the lamina- shaped elastic element 3, by depositing the layer 7 of piezoelectric material, with the electrodes 8 and 9, directly on the surface of the face 3a, 3b.
  • the material of the lamina-shaped elastic element 3 can be any elastic material.
  • the lamina-shaped elastic element 3 is made of an elastic material that is resistant to high temperatures, for example alumina .
  • Figures 4 and 5 there is illustrated the direct application of the torsional actuator 1 to a lamina-shaped elastic element 3.
  • the lamina- shaped elastic element 3 is constrained, at a first end 4 to a constraining element 5, shown only schematically by a dashed line, whilst it is free at a second end 6, opposite the first end 4.
  • the electrodes 8 and 9 of each piezoelectric transducer 1 are embedded in the layer 7 of piezoelectric material and this association between electrodes and piezoelectric material makes an efficient conversion of the electric energy into mechanical energy or vice versa possible.
  • the layer of piezoelectric material preferably has a thickness of approximately 50 micron, preferably of approximately 30 micron.
  • Figure 6 illustrates the application to a lamina-shaped elastic element 3, in a similar manner to that illustrated in Figures 4 and 5, of transducers Ia according to the invention, made according to a version of the present invention.
  • each transducer Ia comprises two layers 7 of piezoelectric material between which the first electrode 8 and the second electrode 9 are enclosed. This embodiment permits even more efficient conversion of the electric energy into mechanical energy or vice versa inasmuch as each electrode 8 and 9 is in contact with the piezoelectric material on both the faces thereof.
  • FIG 7 illustrates the application to a lamina- shaped elastic element 3, in a similar way to that illustrated in Figures 4, 5 and 6, of transducers Ib according to the invention, made according to a further version of the present invention.
  • each transducer Ib comprises a plurality of layers 7 of piezoelectric material in each of which respective electrodes 8 and 9 are embedded.
  • This embodiment enables the efficiency of conversion of electric energy into mechanical energy or vice versa to be improved further inasmuch as the plurality of layers amplifies the efficacy of the conversion of electric energy into mechanical energy or vice versa.
  • each arrangement of interdigitated electrode elements could be enclosed in a geometrical figure of different shape from the rectangle.
  • each arrangement could be tilted with respect to the axis B of the lamina 3 at an angle other than 45° or 135°.
  • some particular applications of torsional transducers could require arrangements with different tilts.
  • a torsional effect is achieved with arrangements tilted at angles different from 45° and 135°, provided that such tilt is not equal to 90° with respect to the torsional axis of the transducer.
  • the piezoelectric material preferably consists of a mixture of lead zirconate titanate and is produced according to the usual procedure for manufacturing piezoelectric films.
  • the electrodes consist of an electrically conductive material, preferably a platinum and gold alloy or palladium and silver alloy.
  • the piezoelectric material of the transducer 1 according to the invention is polarised, when the transducer 1 is made, supplying the electrodes 8 and 9 with direct voltage. This polarisation is achieved at a voltage that is less than the dielectric rigidity of the piezoelectric material and at a temperature that is less than the critical Curie point, the temperature at which the material loses its piezoelectric properties .
  • the transducer 1 according to the invention is supplied by applying to the electrodes 8 and 9 alternating voltage V at a frequency that is equal to the resonance frequency of the lamina-shaped elastic element to which the transducer 1 is applied, so that the lamina-shaped elastic element becomes resonant.
  • a lamina-shaped elastic element 3 when the lamina-shaped elastic element becomes resonant, the electric energy supplied to the transducer 1 is converted into mechanical energy, stressing the lamina-shaped elastic element 3 with a first shearing stress on a face, and with a second shearing stress on the opposite face that, being suitably tilted, induce torsion in the lamina- shaped elastic element, without generating a bending stress.
  • the lamina- shaped elastic element 3 achieves torsion and, as each arrangement of electrode elements 17, 19 has a length equal to ⁇ /4 for a total length of ⁇ /2, the lamina-shaped elastic element 3 starts torsional vibration, describing a half wave that corresponds to the half wave of the sine curve of the main harmonic.
  • the first arrangement of interdigitated electrode elements 17 stresses the lamina-shaped elastic element 3, which starts torsional vibration, describing the first half of the half wave of the sine curve of the main harmonic (that is from 0 to maximum amplitude of the sine curve)
  • the second arrangement 19 of interdigitated electrode elements stresses the lamina- shaped elastic element 3 that starts torsional vibration, describing the second half of the half wave of the sine curve of the main harmonic (that is from maximum amplitude to 0) .
  • the lamina- shaped elastic element 3 will start torsional vibration, describing respectively the first half of the half wave of the sine curve of the main harmonic (that is from 0 to maximum amplitude of the sine curve) and 3 A of the sine curve of the main harmonic (that is a half wave followed by a half wave of opposite type) . It should be noted that, in order to maximise the efficacy of the torsional vibration according to the sine curve of the main harmonic, it is preferably for the length of the lamina-shaped elastic element 3 to be approximately equal to the total length of the electrodes 8, 9, associated with the layer 7 of piezoelectric material .

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  • Measuring Fluid Pressure (AREA)
  • Surgical Instruments (AREA)
  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)

Abstract

La présente invention concerne un transducteur piézoélectrique de torsion (1 ; Ia ; Ib) qui comprend un substratum en forme de plaque mince (2), au moins une couche (7) du matériau piézoélectrique étant associée à un côté dudit substratum (2), ladite couche (7) étant associée de façon opérationnelle à au moins une première électrode (8) et une seconde électrode (9) qui sont isolées électriquement l’une de l’autre, chacune parmi ladite première électrode (8) et ladite seconde électrode (9) étant pourvue d’une pluralité d’éléments électrodes respectifs (12 ; 14) qui sont parallèles les uns aux autres, lesdits éléments électrodes (12 ; 14) définissant au moins un agencement (17 ; 19 ; 21) d’éléments électrodes interdigités qui s’étendent dans une direction inclinée par rapport à un axe longitudinal (A) du transducteur piézoélectrique (1 ; Ia ; Ib).
PCT/IB2009/053127 2008-07-21 2009-07-20 Transducteur piézoélectrique de torsion Ceased WO2010010502A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT000197A ITMO20080197A1 (it) 2008-07-21 2008-07-21 Trasduttore piezoelettrico torsionale
ITMO2008A000197 2008-07-21

Publications (1)

Publication Number Publication Date
WO2010010502A1 true WO2010010502A1 (fr) 2010-01-28

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PCT/IB2009/053127 Ceased WO2010010502A1 (fr) 2008-07-21 2009-07-20 Transducteur piézoélectrique de torsion

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IT (1) ITMO20080197A1 (fr)
WO (1) WO2010010502A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010128864A1 (fr) * 2009-05-05 2010-11-11 Sinvent As Dispositif de conversion d'énergie
WO2012037045A1 (fr) * 2010-09-16 2012-03-22 Eastman Kodak Company Transducteur piézoélectrique présentant une répartition améliorée du champ électrique
WO2018029695A1 (fr) * 2016-08-10 2018-02-15 Technion Research And Development Foundation Limited Dispositifs piézo-électriques à électrodes alignées obliquement

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000051190A1 (fr) * 1999-02-26 2000-08-31 Active Control Experts, Inc. Ensemble actionneur d'extension
US20040040132A1 (en) * 1999-10-29 2004-03-04 Usa As Represented By The Administrator Of The National Aeronautics And Space Administration Piezoelectric composite apparatus and a method for fabricating the same
WO2007104784A1 (fr) * 2006-03-16 2007-09-20 Ceramtec Ag Actionneurs multicouches avec électrodes interdigitales

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000051190A1 (fr) * 1999-02-26 2000-08-31 Active Control Experts, Inc. Ensemble actionneur d'extension
US20040040132A1 (en) * 1999-10-29 2004-03-04 Usa As Represented By The Administrator Of The National Aeronautics And Space Administration Piezoelectric composite apparatus and a method for fabricating the same
WO2007104784A1 (fr) * 2006-03-16 2007-09-20 Ceramtec Ag Actionneurs multicouches avec électrodes interdigitales

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010128864A1 (fr) * 2009-05-05 2010-11-11 Sinvent As Dispositif de conversion d'énergie
WO2012037045A1 (fr) * 2010-09-16 2012-03-22 Eastman Kodak Company Transducteur piézoélectrique présentant une répartition améliorée du champ électrique
WO2018029695A1 (fr) * 2016-08-10 2018-02-15 Technion Research And Development Foundation Limited Dispositifs piézo-électriques à électrodes alignées obliquement
US10957843B2 (en) 2016-08-10 2021-03-23 Technion Research And Development Foundation Limited Piezoelectric devices with obliquely aligned electrodes

Also Published As

Publication number Publication date
ITMO20080197A1 (it) 2010-01-22

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