EP0650642A1 - Dispositif de deflexion ceramique - Google Patents

Dispositif de deflexion ceramique

Info

Publication number
EP0650642A1
EP0650642A1 EP93916053A EP93916053A EP0650642A1 EP 0650642 A1 EP0650642 A1 EP 0650642A1 EP 93916053 A EP93916053 A EP 93916053A EP 93916053 A EP93916053 A EP 93916053A EP 0650642 A1 EP0650642 A1 EP 0650642A1
Authority
EP
European Patent Office
Prior art keywords
electrostrictive
ceramic material
ceramic
layer
deflection
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.)
Withdrawn
Application number
EP93916053A
Other languages
German (de)
English (en)
Inventor
Steven John Butcher
Donald Harry Maguire Grange Farm KINGS
James David Hobby
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.)
Vesuvius Holdings Ltd
Original Assignee
Cookson Group PLC
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.)
Filing date
Publication date
Application filed by Cookson Group PLC filed Critical Cookson Group PLC
Publication of EP0650642A1 publication Critical patent/EP0650642A1/fr
Withdrawn legal-status Critical Current

Links

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
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
    • H10N30/2041—Beam type
    • H10N30/2042—Cantilevers, i.e. having one fixed end

Definitions

  • the present invention relates to a ceramic deflection device and, in particular, to a method of producing and operating a monolithic ceramic deflection device and displacement sensor which does not employ a piezoelectric sensor.
  • Ceramic bending devices utilizing the converse piezoelectric effect are well known in the art. This is the phenomenon by which an applied electric field generates a proportional shape change in such materials. Devices often take the form of so-called bimorphs and multimorphs. The operating principle is identical in both cases. Alternating layers of piezoelectric ceramic are poled, usually in antiparallel directions. The application of an electric field induces a transverse compressive strain in those layers having polar directions parallel to the field, due to the piezoelectric coefficient d_. of the piezoelectric ceramic material. Conversely, transverse tensile strain is induced in layers poled antiparallel to the applied field.
  • the free end of the device is deflected by an amount determined by the magnitude of the applied field, d and various geometrical factors.
  • the displacement is reversed on reversal of the field direction. It is- usual to apply the same electric field across all of the layers of the device.
  • EP-A-0137148 describes such a piezoelectric bimorph constructed from piezoelectric ceramic layers which are poled.
  • This device has the advantage of a monolithic sensor enabling feedback control.
  • the piezoelectric sensor portion of the device operates without the application of an externally applied electric bias field.
  • the device is made to bend by the application of an electric field to the remainder. This places a stress on the sensor portion, causing current to flow which can be related to the displacement of the element.
  • GB-A-2006541 discloses a piezoelectric bimorph which has a pair of oppositely polarized piezoelectric elements bonded to a common substrate.
  • a drive circuit applies a deflection voltage to each element in the same sense as the polarization of the element and thus avoids depolarization of the elements.
  • the device does not include a displacement sensor.
  • EP-A-0262637 discloses a piezoelectric bimorph device in which the piezoelectric ceramic layers are poled in the same direction and the application of an electric field across each layer causes bending.
  • the device does not include a displacement sensor.
  • two ceramic layers are bonded, in such a way as to enable electrical contact, to the major surfaces of a metal shim and electrodes applied to their opposite surfaces.
  • the application of an electric field between the metal shim and the upper external electrode causes upwards deflection.
  • M or Q 12 which places the upper ceramic layer under compressive strain.
  • the deflection obtained varies, amongst others, as a function of the square of the applied field and, therefore, reversal of the electic field direction induces identical upwards deflection.
  • the electric field is applied between the metal shim and the lower electrode, downwards deflection is produced, regardless of the field direction.
  • the present invention provides a monolithic ceramic device comprising an integral electrostrictive deflection element and a displacement sensor which device comprises two layers of an electrostrictive ceramic material with a central electrode sandwiched therebetween, the outer surfaces of each layer of the ceramic material having attached thereto at least one conducting electrode and means for applying a bias field across a single layer of the electrostrictive ceramic material.
  • the central electrode of the deflection element of the present invention is generally connected to the earth .
  • the electrostrictive deflection device and sensor of the present invention together form a monolithic element, i.e. the sensor is an integral part of the device rather than, for example, a bonded strain gauge or capactive displacement sensor.
  • the present invention also includes within its scope a method for the fabrication of a monolithic element as defined above, which method comprises forming a sandwich of a central electrode between two layers of an electrostrictive ceramic material, the outer surface of each of the layers of the ceramic material having a conducting electrode formed thereon.
  • the monolithic ceramic device may be formed by bonding individual ceramic plates onto a metal substrate which forms the central electrode, for example by means of an adhesive, or by depositing the electrostrictive ceramic material onto the metal substrate.
  • the electrodes may be attached to the outer surface of each layer of the electrostrictive ceramic material by electrodeposition or other methods known in the art.
  • the monolithic device may be formed by the method of tape casting the ceramic material, electroding, forming a laminate and firing the structure, in a manner similar to that used in the production of multilayer ceramic capacitors.
  • the present invention also includes within its scope a method of operating an electrostrictive deflection element and displacement sensor as hereinbefore defined, which method comprises applying a potential to the conducting electrode on one layer of the electrostrictive ceramic material and applying a d.c. bias voltage to the conducting electrode on the other layer of the electrostrictive ceramic material, and measuring the charge.
  • the charge, Q which is generated by the sensor portion of the structure may be measured by conventional techniques.
  • the deflection of the electrostrictive deflection element may thus be controlled by a feedback mechanism.
  • Figure 1 is a schematic illustration of the device of the present invention
  • Figure 2 is a schematic illustration of the device of the invention caused to deflect upwardly
  • Figure 3 is a schematic illustration of the device of the invention caused to deflect downwardly; and Figure 4 is a graph of the sensor output voltage against the applied voltage for the device as described in the Example.
  • Electrodes 5 and 6 are formed on the outer surfaces of layers 1 and 2.
  • the device is clamped in position by means of clamps 7 and 8.
  • the connections to the electrodes 5 and 6 are shown at 9 and 10, respectively.
  • Vb A d.c. bias voltage, Vb, is simultaneously applied to the lower electrode 6 and causes the lower section of the device to act as a sensor, generating a charge flow which is proportional to the change in displacement.
  • the d.c. bias field causes a deflection which opposes that generated by the deflecting portion. Consequently, the d.c. bias voltage may be maintained at a relatively small value, typically about 20 V, to obtain large displacements. It follows, however, that the effective stiffness of the device, which is the resistance to deflection, can be controlled by variation of the d.c. bias, a larger d.c. bias providing a greater resistance to deflection. This type of device may be used in active vibration control.
  • a device of the type as described with reference to Figure 1 of the accompanying drawings was prepared from an electrostrictive material based on lead magnesium niobium titanate, Pb(Mg.Nb ? )0 -PbTi0_.
  • the fired device consisted of layers of the ceramic material approximately 200 ⁇ m thick, separated by a central palladium electrode. Electrical contacts were made to the surfaces of the ceramic layers as shown in Figure 1.
  • a d.c. bias voltage of 15 V was applied to the ceramic layer chosen to operate as a sensor and a triangle wave drive voltage was applied to the ceramic layer chosen to operate as an actuator. Displacement of the actuator placed a stress on the sensor, causing the generation of a proportional output signal.
  • the sensor output signal (in mV) is plotted in Figure 4 as a function of the voltage applied to the actuator.
  • the response is electrostrictive in nature, as expected for the motion of the actuator.
  • the offset in the response is a natural consequence of the application of the d.c. bias to the sensor portion and can be removed by the application of an equal d.c. bias offset to the actuator portion.

Landscapes

  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

Un dispositif céramique monolithique doté d'un élément de déflexion électrostrictif intégral et d'un capteur de déplacement comprend deux couches de matière céramique électrostrictive entre lesquelles est disposée une électrode centrale. Sur les surfaces extérieures de chaque couche de la matière céramique sont fixés au moins une électrode conductrice et des moyens d'application d'un champ polarisé qui traverse une seule couche de la matière céramique électrostrictive.
EP93916053A 1992-07-17 1993-07-13 Dispositif de deflexion ceramique Withdrawn EP0650642A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB9215254 1992-07-17
GB929215254A GB9215254D0 (en) 1992-07-17 1992-07-17 Ceramic deflection device
PCT/GB1993/001456 WO1994002965A1 (fr) 1992-07-17 1993-07-13 Dispositif de deflexion ceramique

Publications (1)

Publication Number Publication Date
EP0650642A1 true EP0650642A1 (fr) 1995-05-03

Family

ID=10718897

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93916053A Withdrawn EP0650642A1 (fr) 1992-07-17 1993-07-13 Dispositif de deflexion ceramique

Country Status (3)

Country Link
EP (1) EP0650642A1 (fr)
GB (2) GB9215254D0 (fr)
WO (1) WO1994002965A1 (fr)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2364965B (en) * 1997-09-05 2002-04-03 1 Ltd Manufacture of piezoelectric print head
US6677034B1 (en) 1997-09-05 2004-01-13 1 . . . Limited Aerogels, piezoelectric devices, and uses therefor
GB2362976B (en) 2000-05-31 2005-04-27 Seiko Epson Corp Memory device
GB2362989B (en) * 2000-05-31 2004-03-24 Seiko Epson Corp Piezoelectric devices
US6540618B1 (en) * 2000-09-26 2003-04-01 The Torrington Company Steering column slider assembly
US7336022B2 (en) * 2001-06-27 2008-02-26 Siemens Aktiengesellschaft Piezoelectrical bending converter
KR20040040791A (ko) * 2002-11-08 2004-05-13 정성필 지반 개량용 슈를 이용한 앵커공법
DE102005024192A1 (de) * 2005-05-25 2006-11-30 Siemens Ag Piezoelektrischer Biegewandler mit Sensorelement zum Erfassen einer Auslenkung des Biegewandlers, Verfahren zum Erfassen der Auslenkung des Biegewandlers und Verwendung der erfassten Auslenkung
DE102011080114A1 (de) 2011-07-29 2013-01-31 Siemens Aktiengesellschaft Erfassen eines Verformungsparameters eines piezoelektrischen Biegewandlers

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5994103A (ja) * 1982-11-19 1984-05-30 Nec Corp 電気機械変換器の制御装置
US4625176A (en) * 1983-09-13 1986-11-25 International Business Machines Corporation Electrostatic probe

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9402965A1 *

Also Published As

Publication number Publication date
GB2284298A (en) 1995-05-31
GB2284298B (en) 1996-05-15
GB9500800D0 (en) 1995-03-08
WO1994002965A1 (fr) 1994-02-03
GB9215254D0 (en) 1992-09-02

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