US2166763A - Piezoelectric apparatus and circuits - Google Patents

Piezoelectric apparatus and circuits Download PDF

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Publication number
US2166763A
US2166763A US131160A US13116037A US2166763A US 2166763 A US2166763 A US 2166763A US 131160 A US131160 A US 131160A US 13116037 A US13116037 A US 13116037A US 2166763 A US2166763 A US 2166763A
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United States
Prior art keywords
relay
piezoelectric
electromotive force
contact
electrodes
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Expired - Lifetime
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US131160A
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English (en)
Inventor
Warren P Mason
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to NL51407D priority Critical patent/NL51407C/xx
Priority to BE426805D priority patent/BE426805A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US131160A priority patent/US2166763A/en
Priority to GB4405/38A priority patent/GB501691A/en
Priority to CH208062D priority patent/CH208062A/de
Priority to FR835337D priority patent/FR835337A/fr
Application granted granted Critical
Publication of US2166763A publication Critical patent/US2166763A/en
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    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04F—FINISHING WORK ON BUILDINGS, e.g. STAIRS, FLOORS
    • E04F11/00—Stairways, ramps, or like structures; Balustrades; Handrails
    • E04F11/02—Stairways; Layouts thereof
    • E04F11/104—Treads
    • E04F11/112—Treads of metal or with an upper layer of metal
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H57/00—Electrostrictive relays; Piezoelectric relays

Definitions

  • Substantially all relays now in use having movi able contacts are of the electromagnetic type.
  • An electromagnetic relay operates by virtue of a magnetic field which arises when an electric current flows through the relay winding and which persists substantially for the duration of that current. It follows that the relay actuating force which the magnetic field produces is a function of the intensity of current in the relay winding. In the case of relays operated over long lines or in circuits of high resistance the operl5 ating force may be so small as to make electromagnetic relays impractical without amplifiers or other devices for increasing the actuating force. Moreover, the flow of current in the circuit of therelay winding is attended with an engg ergy loss which in the case of long continued periods of operation, or large numbers of relays may be very costly.
  • a piezoelectric body responds to a properly imposed electric fleld to alter its position or conformation in consequence of the mechanical stresses induced in it by the field. If such a body, as for example, aplate of Rochelle salt crystal be mounted by fixing one surface or margin on a support and be provided with a pair 39 of electrodes coated or otherwise attached on its surfaces or position adjacent thereto, an electromotive force applied between the electrodes will set up such a stress as to cause a corresponding displacement of the free portions of the body.
  • an egctric contact element carried by such a displaced portion may be brought into engagement with a fixed position electric contact element upon application of an electromotive force to the electrodes of the piezoelectric body.
  • a local circuit including a source of current and a translating device as, for example, a lamp be connected to the twocontact members
  • the piezoelectric body will operate as a relay to close the local circuit so that the lamp may be lighted 45. by energy from the source of current.
  • Piezoelectric relays have several inherent advantages. Because they respond to potential upon their electrodes they may be operated by the very small quantity of electricity necessary to so charge their electrodes to the required operating potential. Inasmuch as the charging currents are extremely small, the operating circuit losses are correspondingly small.
  • the operating circuit may sufiice to transmit suflicient 55- energy to operate the relay even if its resistances are very high. It is quite possible to operate a piezoelectric relay over an operating circuit having a resistance of, for example, 1 megohm. Having once charged the electrodes and actuated the relay no further operating current is rer, quired except the infinitesimal amount necessary to compensate for leakage and maintain the charge and the relay remains operated until the charge on its electrodes is removed. The energy required is substantially only that necessary to lo initially actuate the relay and the usual holding current loss is almost entirely avoided. Moreover, these advantagesare attained by a structure which is relatively simple and inexpensive to construct and which is rapid in operation. 15
  • An object of the invention is to provide a relay of the piezoelectric type which shall be quickacting.
  • Another object of the invention is to prevent chattering at the contacts of a piezoelectric re- 50 lay.
  • An additional object of the invention is to control the time of operation after application of the operating electromotive force and of release after withdrawal of the operating electromotive force 26 to secure any desired time delay or duration of operation-of a piezoelectric relay.
  • a further object of the invention is to produce a piezoelectric element that may be quick-acting and at thesame time may impart a suificient 0 motion to its movable contact to operate circuits requiring'considerable contact separation.
  • a still further object of the invention is to provide a piezoelectric relay element which may be rugged enough to withstand the stresses encoun- 135 tered in rapid operation for long periods.
  • a still further object of the invention is to render the piezoelectric element of a piezoelectric relay relatively immune to deteriorating atmospheric effects.
  • the operating element of a piezoelectric relay which carries the movable contact c'onsists of thin blades of plezo'a electric material clamped at one end at which they are made considerably thicker in the interest of ruggedness.
  • a rigid beam structure of material of low density may be cemented to the piezoelectric blades near. their free ends to-carry the movable electric contact at the center 01 66 f percussion of the composite structure and to multiply the displacement available. Chattering of the contacts may be reduced by mechanical and detailed speciflcation.
  • Fig. 1 illustrates in perspective the mounting of the piezoelectric blades which form the operating part of a piezoelectric relay
  • FIG. 3 an elevation of the structure shown in Fig, 2; v
  • Fig. 4 a diagram to explain the calculations of the displacement available
  • Fig. 5 a modification of the structure of Fig. 1;
  • Fig. 6 a side view of the piezoelectric blades of Fig. 5;
  • Fig. '7 an elevation of the structure shown in Fig. 6.
  • Fig. 8 is a circuit diagram of a system for determining the time of operation of a piezoelectric relay
  • FIG. 9 shows the electrical equivalent circuit of a piezoelectric relay
  • Fig. 10 shows a System for damping a piezoelectric relay
  • Fig. 11 illustrates an expedient for rendering the sensitivity of a piezoelectric relay more nearly uniform under varying temperature conditions
  • Fig. .12 shows a modification of the device of Fi 11 in which the piezoelectric relay is incor-.
  • Fig. 13 shows the electrical diagram of a cir cuit for rendering a piezoelectric relay quick-acting and more sensitiveto a small applied voltage.
  • FIG. 1 there is shown a supporting frame I of insulating material having a base member to mount the relay members in vertical position. attached thereto by screws 4 which may support the ,terminals for the respective leads 5 and 5'.
  • An angle portion 6 of the bracket is provided with a split screw-threaded opening through which works a contact carrying screw 1 having a contact member 8 and an adjustingv head 8. Also,
  • Piezoelectric elements I and ii are preferably formed of Rochelle salt and their principal faces, indicated in Fig. 2, are parallel to the B and C Rochelle salt crystal.
  • the rectangular plates ii and ii are so cut that their central longitudinal axis 0-0 indicated in Fig. 2 is in a direction inclined 45 degrees to the B or C axes of the virgin crystal.
  • the lower end portions of the elements I and i5 indicated at l8 and H are made thicker than the principal portions so that they are less fragile and hence less likely to be fractured by the clamping action of plate i2 and bracket Ii.
  • the displacement of the piezoelectric relay contact 20 may be calculated as follows by reference to Fig. 4. Assuming an effective length 1 from the bending fulcrum of the piezoelectric elements adjacent clamp ll up to the contact 2
  • Figs. 5, 6 and '7 illustrate a modification of the piezoelectric element of-Flgs. -1, 2 and 3 in which the displacement of the moving contact element is increased by positioning it on a rigid beam extension of the piezoelectric element.
  • the moving contact element 20 is mounted on one side of an I beam 23 preferably consisting of two channel shaped members placed back to back to constitute a rigid or substantially unbending beam.
  • a similar contact 20' is mounted on the opposite side.
  • the piezoelectric elements l4 and 15 are slotted at their ends as indicated at 25 to accommodate the I beam which is attached to the piezoelectric elements by some adhesive material such as shellac.
  • the conductive coatings forming the driving electrodes are interrupted shortof the margins adjacent the beam so as not to be electrically connected thereby. Assuming a length of piezoelectric plate Z1 and an additional length 12 of aluminum bar measured up to a contact point carried thereby we may calculate the displacement of the contact point for small displacements from Equation 7 since the aluminum bar will not bend but will have approximately the slope of the end of the piezoelectric plate to which it is cemented.
  • E Young's modulus ofthe piezoelectric material and F the applied force in dynes. -E for Rochelle salt is about 1.5 10 dynes per square cm.'for a plated crystal.
  • the speed of operation of the relay or the time at which it closes its contacts after application of an electromotive force to its circuit is' another important element. Since the piezoelectric element possesses an electrostatic capacity it takes a certain time to build up therein an electromative force suiilcient to actuate the piezoelectric elements. Moreover, once the capacity device is charged to the proper operating potential there is an additional time required for the operation of displacing the movable contact to take place.
  • a piezoelectric element will respond in an interval which is a function of its resonance frequency.
  • the longitudinal or extensional mode of vibration of a Rochelle salt element has a natural frequency expressed by where as before t is the thickness of the Roch lie salt blade and 1 its effective length. Since e fixed contact stop arrests the motion of the mov'Q time interval T1 occurring during the motion will be approximately To the time T1 required for the relay to operate after it has been subjected to the operating potential there must be added the time T2 required for bringing the potential difference between the relay electrodes up to the operating magnitude.
  • the capacity of the electrodes of such a piezoelectric element as was disclosed in Fig. 1 is of theorder of .01 mf. It is, therefore,- apparent that with the capacity 30 decreased to such an extent as practically to eliminate it and with the series resistance reduced from 1 megohm "to 1000 ohms the preoperating time or delay period may be reduced to approximately .00001- second.
  • Such a resistance may comprise an oil-damping element 32 as illustrated in Fig. 1 in which motion of the relay drives a piston which pushes out the oil between the piston and a flat plate behind it. This produces a mechanical resistance which can be adjusted'to any desired value by adjustment. of the flat plate by means of an external knob 33.
  • Each of the three front coatings is directly connected electrically with the corresponding back coating.
  • key 31 When key 31 is 1 closed an actuating eiectromotive force is applied directly between the coating 35 and the single central coating 38 between the two piezoelectric blades. The relay thereupon responds. Any chattering or vibration sets up an alternating piezoelectric eiectromotive force between front and back coatings 34 and front and back coatings It, all acting as a coating of one potential and the central coating SI of the opposite potential.
  • resistance R1 connected between 25 these coatings furnishes an energy dissipation path which provides the desired damping effect.
  • This damping effect can also be obtained by inserting an electrical resistance R in series with the relay of -Flg. 1. This follows from the 30 fact that when the relay tongue strikes the contact it is bent and this produces an additional charge on the relay which is dissipated through the resistance R in a similar way to that employed in the relay of Fig. 10. It' has been shown theoretically that the best value for this resistance R is a value such that it equals the impedance of the relay capacitance at the resonant frequency of the relay; for example, if the relay has a static capacitance of .01 mi. and a resonant frequency of 150 cycles, the best value of R is 40 about 100,000 ohms. This will not appreciably slow up the action of the relay.
  • Rochelle salt has a maximum capacitance and piezoelectric response at about 24.5" C.
  • a condenser C1 of considerably less capacity than the piezoelectric capacitance 29 at 245 .C. may be connected in series with the piezoelectric element as is indicated in Fig. 11.- Hence at 24.5 C. most of the driving electron otive force will be expended across the seriescondenser and the sensitivity of the piezoelectric device will be reduced. As the temperature changes from 245 C.
  • the capacity 29 falls away rapidly and soon becomes less than that of condenser C1 so that the relative portion of the driving voltage eflective on the piezoelectric element is increased in such manner as to tend to compensate for its, reduced'piezoelectric sensitivity.
  • the applied charge may leak of! through the inherent leakage resistance of' the crystal structure as indicated in' dotted lines or a suitablephysical shunt resistance may be provided.
  • a circuit capable of more exact compensation balanced and the piezoelectric element will be 7 same time its capacity and that of elements Ca increase to a magnitude approximating the capacity of elements 02.
  • the bridge thus becomes more nearly. balanced so reducing the electromotive force applied to the piezoelectric elenient and compensating for the increased sensitivity of the piezoelectric element.
  • piezoeiectricrelays in accordance with the present invention may be placed singly or with numbers of other relays in enclosures provided with temperature regulation or with both temperature and-humidity regulation.
  • the broken line recan enclosure for the piezoelectric relay element If it is desirable to make the piezoelectric relay very fast it is necessary to increase the resonance frequency of the piezoelectric element either by making it shorter or thicker. In either case, the sensitivity of the relay will be considerably decreased so that.
  • a circuit arrangement in accordance with that of Fig. 13 may be used in which the piezoelectric element is operated by a relatively large actuating electromotive force controlled by an electron discharge device to the input circuit of which a relatively small electromotive force is applied.
  • a high voltage source is used to actuate the piezoelectric relay very little power is consumed and, accordingly, such a system is of relatively high emciency.
  • the signal input is represented diagrammatically by. the source E1 and the signaling key 39. in series with resistance Re which may represent the resistance of a long line or other circuit over which the signals are to be transmitted.
  • An electron discharge device of the usual type has its input electrodes connected to the signal path just described.
  • the anode circuit of the device 40 includes in series an inductance coil L. a resistance R3 and a twopart space current source E2, Ea the negative terminal of which is connected to the cathode of the discharge device.
  • has its actuating terminals connected respectively to the anode and tothe common junction point of source'Ez, E3. The circuit is so adjusted that the normal space currentpassing through the tube and.
  • the inductance L of the circuit of Fig. 13 is' preferably given such magnitude and so incorporated into the circuit that together with the .inherent capacitance 29 of the relay 4
  • the magnitude of the inductance of L is a representative value for a fast relay and R3 sive to an impressed electromotive force to cause a displacement of a portion of the device, a movable contact mechanically fixed with respect to the displaced portion so that its position is shifted by displacement of said portion, a second contact mounted adjacent said movable contact and adapted to be engaged by the movable contact, and means predesigned to control the rate of application of the eiiective' electromotive force to the electrostatic device to predetermine the interval which elapses after impression of the electromotive force upon the input terminals before the engagement of the contacts.
  • the plates having juxtaposed flat surfaces, means holding the plates together as a unit with their lengths so arranged that one plate tends to shorten when the other plate lengthens, supto and between which an electromotive force may be applied to cause displacement of a portion of the plate, a first contact carried by the displaceable portion, a second contact engageable by the first contact, the piezoelectric plate comprising a thin long member having a much thicker portion adjacent a margin remote from the first contact, and supporting means clamping the thickened portion of the plate whereby the tendency of the clamping to shatter the plate is materially reduced.
  • An electrically operated device comprising two relatively thin long blades of piezoelectric material each having two principal surfaces coated with conductive material, means causing one principal face of one plate to adhere to a principal face of the other, an input terminal connected to the coatings on the exposed faces of both blades a second input terminal connected to the coatings on the adhering faces, each bla'de having an integral thickened portion at one end,
  • a relay comprising an elongated member of piezo-electric material, input electrodes associated with two opposite faces thereof, an individual input contact connected toeach electrode,
  • a relay comprising a plate of piezoelectric material, the piezoelectric constant of which varies with temperature, electrodes associated with the plate, means for mounting the plate to hold one portion thereof relatively fixed, a stationary electrical contact member on said mounting means, a second electrical contact member on the plate and in position to engage the stationary contact member upon application of an electromotive force to the electrodes, and means for maintaining the temperature of the piezoelectric plate within a limited range of temperatures including that at which the piezoelectric constant of the piezoelectric plate is a maximum.
  • An electrostatic relay comprising a member having two electrodes in position to subject the 2,166,763 2.
  • a relay comprising a pair of piezoelectric member to an electric field so as to cause a dis-; placement of the member upon application of an electromotive force to the electrodes, and means to discharge any residual charge upon the electrodes after withdrawal of the applied electromotive force.
  • a relay comprising a piezoelectric element, electrodes mounted adjacent thereto, terminals connected to the electrodes to permit an electrical electromotive force to be impressed thereon to cause fiex'ure of the piezoelectric element, and a yieldable mechanical damping device connected to the element to tend to damp oscillations resulting from the displacement occurring when the condition of charge of the electrodes is suddenly varied.
  • an electron discharge ampli-- bomb having a cathode, an anode and an impedance contrcfi element, input terminals connected to the cathode and impedance control element; an output circuit connected to the anode and cathode, said output circuit including in series two sources of space current and a resistive impedance, the source of current adjacent the resisti'veiimpedance having an electromotive force just sufllcient to compensate for the drop of potential in the resistive impedance, and a piezoelectric relay connected in shunt to the resistive impedance and its adjacent source whereby a normal zero potential difference exists across the piezoelectric relay and a large potential difference is impressed on the relay when an electromotive force is applied between the input terminals.
  • piezoelectric relay in combination, a pair of input terminals, a resistance connected therebetween, a second resistance and a piezoelectric relay element in series therewith connected in shunt to the first resistance
  • a relay comprising a long element of R0- chelle salt having its two principal flat faces in planes parallel to each other and parallel to. the B axis and perpendicular to the A axis of the mother crystal, the longitudinal axis of the piece lying at an angle of 45 degrees with the B axis, a second similar shaped element of Rochelle salt similarly cut, electrodes for each of the pieces of Rochelle salt associated therewith, means con-' necting the electrodes of one piece respectively to the electrodes of the other, means holding the two pieces in fixed back to back relation such 7-5- afrearcs that an electromotive force appliedbetween the electrodes tends to cause one piece to shorten and the other piece to simultaneously lengthen, a
  • An electric relay comprising a pair of piezoelectric plates clamped together, electrodes associated with the platesto subject the plates to an electric field when the electrodes are electrically charged, a pair of input terminals connected to the electrodes in such manner that an electromotive force applied to the input terminals tends to cause one plate to increase in dimension along one direction and to simultaneously cause the other plate to decrease in dimemion along the same direction whereby the assemblage of plates warps from its normal position, a stationary contact'element mounted adjacent the plates, a movable contact element carried by the assemblage of plates formotion into engagement with the stationary contact element, means in series with the input terminals to determine the initiation of theresponse of the relay after an electromotive force is applied to the terminals, means for suppresslng chattering of the contacts upon engagement to insure the precision of the contact interval, and means in shunt to the terminals and having such resistance relative to the magnitude of'the capacity of the electrodes as to predetermine the time of release of the relay after the actuating electro
  • a relay comprising a pair of piezoelectric plates having juxtaposed fiat surfaces, electrostatic capacity elemerits associated with the plates in fixed relation whereby in response to an electromotive force impressed upon the elements the plates are each subjected to an electric field,v
  • a relay system comprising anelectrostatic relay which includes two input tefminals; two output terminals, a pair of electrostatic capacity elements respectively. connected to the input ter- .minals and the electrostatic capacity of which is of the order of .01 microfarad, a pair of contactor elements respectively connected to the output terminals, means physically connected to one of the contactor elements and responsive to relative motion of the capacity elements upon the application of a charging electromotive force to the input terminals to cause engagement oi the contactor elements, and an electrical network connected to the input terminals of the relay which includes a conductive resistive path shunted across the capacity elements to determine the period required for the capacity elements to discharge to a release potential after withdrawal of the applied clectromotive force from the input terminals.
  • a relay system comprising an electrostatic relay which includes two input terminals, two
  • a pair 01' electrostatic capacity elements respectively connected to the input tergminals and the electrostatic capacity of which is of the order of .01 microiarad a pair of contactor elements respectively connected to the output terminals, means physically connected to one of the contactor elements and responsive to relative motion-of the capacity elements upon the application of a charging electromotive force to the input terminals to cause engagement oi. the contactor elements, and an electrical network. connected to the input terminals and including a 1 resistance in series between one of the input ter ,minals and the respectively, connected capacity element to determine the time required for the electrostatic capacity to charge up to a desired operating potential after application of the,
  • a relay comprising a plate of piezoelectric material, the piezoelectric constant of which is a function of the condition of the surrounding atmospheric medium, electrodes associated with the plate,. means for mounting the plate to hold one portion thereof relatively fixed, a stationary electrical contact member on said mounting means, a second electrical contact member on the plate and in position to engage the stationary contact member upon application of an electromotive' force to the electrodes, and means for preventing change of the magnitude of the piezoelectric constant in consequence of change in the condition of the atmospheric medium surrounding the relay.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Thermally Actuated Switches (AREA)
  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
US131160A 1937-03-16 1937-03-16 Piezoelectric apparatus and circuits Expired - Lifetime US2166763A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NL51407D NL51407C (sv) 1937-03-16
BE426805D BE426805A (sv) 1937-03-16
US131160A US2166763A (en) 1937-03-16 1937-03-16 Piezoelectric apparatus and circuits
GB4405/38A GB501691A (en) 1937-03-16 1938-02-11 Piezo-electric apparatus for repeating electric impulses
CH208062D CH208062A (de) 1937-03-16 1938-03-15 Piezoelektrisches Relais.
FR835337D FR835337A (fr) 1937-03-16 1938-03-16 Appareils piezo-électriques et circuits les utilisant

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US131160A US2166763A (en) 1937-03-16 1937-03-16 Piezoelectric apparatus and circuits

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US2166763A true US2166763A (en) 1939-07-18

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US131160A Expired - Lifetime US2166763A (en) 1937-03-16 1937-03-16 Piezoelectric apparatus and circuits

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US (1) US2166763A (sv)
BE (1) BE426805A (sv)
CH (1) CH208062A (sv)
FR (1) FR835337A (sv)
GB (1) GB501691A (sv)
NL (1) NL51407C (sv)

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2479173A (en) * 1944-07-26 1949-08-16 Gen Electric Circuit and starter for electric discharge devices
US2714642A (en) * 1952-07-10 1955-08-02 Bell Telephone Labor Inc High speed relay of electromechanical transducer material
US2916578A (en) * 1955-04-01 1959-12-08 Electric Machinery Mfg Co Electrostrictive capacitive relay having tension mounted actuator
US2967956A (en) * 1955-04-19 1961-01-10 Gulton Ind Inc Transducer
US3004176A (en) * 1959-03-30 1961-10-10 Bell Telephone Labor Inc Electromechanical transducers
US3109153A (en) * 1960-11-18 1963-10-29 Gen Dynamics Corp Adjustable piezoelectric wave filter having two resonance peaks
US3613589A (en) * 1955-12-23 1971-10-19 Us Army Bomb fuzing system
FR2119031A1 (sv) * 1970-12-24 1972-08-04 Siemens Ag
US3777093A (en) * 1972-05-25 1973-12-04 R Sterns Electromechanical relay
JPS5161237U (sv) * 1974-11-07 1976-05-14
US4403166A (en) * 1980-12-19 1983-09-06 Matsushita Electric Industrial Co., Ltd. Piezoelectric relay with oppositely bending bimorphs
US4538087A (en) * 1984-06-11 1985-08-27 General Electric Company Alternating current driven piezoelectric latching relay and method of operation
US4553061A (en) * 1984-06-11 1985-11-12 General Electric Company Piezoelectric bimorph driven direct current latching relay
US4595855A (en) * 1984-12-21 1986-06-17 General Electric Company Synchronously operable electrical current switching apparatus
US4608506A (en) * 1983-03-31 1986-08-26 Tokyo Shibaura Denki Kabushiki Kaisha Temperature compensated drive for a piezoelectric displacement generator
US4620124A (en) * 1984-12-21 1986-10-28 General Electric Company Synchronously operable electrical current switching apparatus having increased contact separation in the open position and increased contact closing force in the closed position
US4620123A (en) * 1984-12-21 1986-10-28 General Electric Company Synchronously operable electrical current switching apparatus having multiple circuit switching capability and/or reduced contact resistance
US4626698A (en) * 1984-12-21 1986-12-02 General Electric Company Zero crossing synchronous AC switching circuits employing piezoceramic bender-type switching devices
US4654555A (en) * 1983-09-05 1987-03-31 Omron Tateisi Electronics Co. Multi pole piezoelectrically operating relay
US4658154A (en) * 1985-12-20 1987-04-14 General Electric Company Piezoelectric relay switching circuit
US4669160A (en) * 1984-12-21 1987-06-02 General Electric Company Method for prepolarizing and centering a piezoelectric ceramic switching device
US4670682A (en) * 1984-12-21 1987-06-02 General Electric Company Piezoelectric ceramic switching devices and systems and method of making the same
US4678957A (en) * 1986-06-24 1987-07-07 General Electric Company Piezoelectric ceramic switching devices and systems and methods of making the same
US4680840A (en) * 1984-12-21 1987-07-21 General Electric Company Method for prepolarizing and centering a piezoceramic power switching device
US4689517A (en) * 1984-12-21 1987-08-25 General Electric Company Advanced piezoceramic power switching devices employing protective gastight enclosure and method of manufacture
WO1988001438A1 (en) * 1986-08-15 1988-02-25 Pacific Bell Piezoelectric switch
US4967568A (en) * 1988-03-25 1990-11-06 General Electric Company Control system, method of operating an atmospheric cooling apparatus and atmospheric cooling apparatus
USRE33568E (en) * 1984-12-21 1991-04-09 General Electric Company Piezoelectric ceramic switching devices and systems and methods of making the same
USRE33577E (en) * 1984-12-21 1991-04-23 General Electric Company Advanced piezoceramic power switching devices employing protective gastight enclosure and method of manufacture
USRE33587E (en) * 1984-12-21 1991-05-14 General Electric Company Method for (prepolarizing and centering) operating a piezoceramic power switching device
USRE33618E (en) * 1984-12-21 1991-06-25 General Electric Company Method for initially polarizing and centering a piezoelectric ceramic switching device
USRE33691E (en) * 1984-12-21 1991-09-17 General Electric Company Piezoelectric ceramic switching devices and systems and method of making the same
WO1996017192A1 (en) * 1994-12-01 1996-06-06 Sortex Limited Piezoelectric diaphragm valve for use in sorting apparatus ejectors
US6497660B1 (en) * 2000-10-18 2002-12-24 Koninklijke Philips Electronics N.V. Ultrasound imaging device
US11435461B2 (en) 2019-07-19 2022-09-06 GE Precision Healthcare LLC Method and system to prevent depoling of ultrasound transducer
US11464494B2 (en) 2019-07-19 2022-10-11 GE Precision Healthcare LLC Method and system to revert a depoling effect exhibited by an ultrasound transducer

Cited By (38)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2479173A (en) * 1944-07-26 1949-08-16 Gen Electric Circuit and starter for electric discharge devices
US2714642A (en) * 1952-07-10 1955-08-02 Bell Telephone Labor Inc High speed relay of electromechanical transducer material
US2916578A (en) * 1955-04-01 1959-12-08 Electric Machinery Mfg Co Electrostrictive capacitive relay having tension mounted actuator
US2967956A (en) * 1955-04-19 1961-01-10 Gulton Ind Inc Transducer
US3613589A (en) * 1955-12-23 1971-10-19 Us Army Bomb fuzing system
US3004176A (en) * 1959-03-30 1961-10-10 Bell Telephone Labor Inc Electromechanical transducers
US3109153A (en) * 1960-11-18 1963-10-29 Gen Dynamics Corp Adjustable piezoelectric wave filter having two resonance peaks
FR2119031A1 (sv) * 1970-12-24 1972-08-04 Siemens Ag
US3777093A (en) * 1972-05-25 1973-12-04 R Sterns Electromechanical relay
JPS5161237U (sv) * 1974-11-07 1976-05-14
US4403166A (en) * 1980-12-19 1983-09-06 Matsushita Electric Industrial Co., Ltd. Piezoelectric relay with oppositely bending bimorphs
US4608506A (en) * 1983-03-31 1986-08-26 Tokyo Shibaura Denki Kabushiki Kaisha Temperature compensated drive for a piezoelectric displacement generator
US4654555A (en) * 1983-09-05 1987-03-31 Omron Tateisi Electronics Co. Multi pole piezoelectrically operating relay
US4538087A (en) * 1984-06-11 1985-08-27 General Electric Company Alternating current driven piezoelectric latching relay and method of operation
US4553061A (en) * 1984-06-11 1985-11-12 General Electric Company Piezoelectric bimorph driven direct current latching relay
USRE33618E (en) * 1984-12-21 1991-06-25 General Electric Company Method for initially polarizing and centering a piezoelectric ceramic switching device
US4595855A (en) * 1984-12-21 1986-06-17 General Electric Company Synchronously operable electrical current switching apparatus
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Also Published As

Publication number Publication date
FR835337A (fr) 1938-12-19
GB501691A (en) 1939-03-03
CH208062A (de) 1939-12-31
BE426805A (sv)
NL51407C (sv)

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