US2624853A - Flexure-sensitive electromechanical transducer device - Google Patents

Description

H. c. PAGE 2,62

FLEXURE-SENSITIVE ELECTROMECHANICAL TRANSDUCER DEVICE Jan.

Filed Dec. 28, 1948 FIG-2 Fl .l

SOURCE FIG. 5

JNVENTOR. HARRY C. PAGE ATTO R N EY Patented Jan. 6, 1953 UNITED STATES F PATENT OFFICE v FLEXURE:SENSITIVE ELECTROMECHANI- .ICAIL TBANSDUCE V EV C HarryCQP-age';Cleveland Heights; ohio assignor to The Brush .jDe.velopmentf Company, Cleveland, Ohio,; a corporation of, Ohio Application December 28, 1948, Serial .No. 67,741

(Cl;i 3'10 -8.5)

. 11 Claims. 1

This invention relates to a transducerdevice -electromechanically sensitive-to flexure of an electromechanically responsive element of the device. More particularly, this inventionrelates to a bending-sensitive or twisting-sensitive electromechanical transducer device in which such flex- --ure is associated-with mechanical reaction between portions of the device containing material having electromechanical properties such-that theindividual-portions tend to deform 'to differenit extents during-transducing from electrostatic-fieldenerg-y to mechanical energy.

:Inan application for Letters Patent ofthe -United States, Ser. No. 67645, filed concurrently herewith in the-name of Hans- G. 'Baerwald'and assigned to thesamev assignee as the present invention, there is disclosedand claimed-,inter alia,

- a iiexure-sensitive transducer device comprising a substantially homogeneous body having a-substantial variation with location through thebody of local electromechanical transducing properties. Oneportion of the body is conditionedby the applicationzof a unidirectionalelectric-potential to provide a 1 substantial --transducingresponse characteristic. In accordance with one arrangement disclosed and claimed-in-the aforementioned application; thehomogeneous body- -is madeup of permanently polarizable polycrystalline dielectric material; "such as -barium titanate 7 "material,- which has been conditioned by"-p'olari-.

zation with a-unidirectional-potential but a portion of which has been at least partially depolarized by localized heating. The depolarized portionexhibits practically no electromechanical response. This portion'may'occupy, say,,about half of the thickness "of a plate-shaped 'or barshaped body. When the body "is subjected to, an incremental electric potential, the portion which remains polarizedtends to expand or contract.

- Mechanicalreaction of this electromechanic'ally. responsive portion with the relatively unresponsive half of the body produces a flexure, specifically, a bending of lines extending lengthwise in the body, as upon the application of asignal potential across the bar. Conversely,subjecting the bar-to a bending displacement results in the appearance of a signal potential across the bar.

The'transducer device just described is very simple structurally and exhibits several advantages over the composite bender devices of'the prior art, which comprise two or more electroded plates or bars cemented together along major surfaces thereof. Nevertheless, a transducer device utilizing-such a homogeneous polycrystalline body requires careful-treatmentto produce-difl "-ferent electromechanical transducing-response --characteristics'in-diiierent portions of the body.

' Whenthe variation of the local electromechanical-transducing properties within the body is ---achieved by electrostatic prepolarization and subsequent localized heating, only arepetition of this type of carefultreatment, utilizing special equipment, -can reinstate the device to a--useful condition-if the polarization subsequently should -be disturbed, for example by inadvertentheating -or lay-the application-of anunusuallyhighzsig- .nal potential-to the body.

-Accordingly,"it is an object of-the present invention to provide a new and-improved trans- ''ducer device electromechanically sensitive --to- :flexure which substantially avoidssome-orall -of the limitations and disadvantages of devices hitherto proposed.

It is another object of the invention to provide a new :and improved transducer device electro- --mechanically sensitive-to flexure and of simpler construction .thancomposite bender and twister devices.

It 'isa further-vobjectof the invention to provide: a newiandzimproved flexureesensitivetrans- ",ducer-device which-may be made to exhibit: a ;-=reasonably;..'.high efliciencysofa.transducingafter ':,.2;'Sim131e. electrical treatment.

' It,is a still further'object cr me-invention to awprovide a novel, inexpensive, and. easily: manuzfactured fiexurensensitive transducer device.

accordance-With the invention, z t-transducer xdevice -electromechani-cally sensitive--toiiexure comprises. abody substantially free of structural discontinuities, having one substantial portionof a dielectric material which is conditioned bythe application of a unidirectional electric potential to provide 'a substantial transducing-response characteristic as between mechanical signal energy and electrostatic-field signal energy and having another substantial portion of dielectric also comprises means including electrodes adja-- material of diiierent composition which upon the "application'of saidunidirecti'onal potentialhas a transducing-response characteristic a's'between the aforementioned signal energies substantially different from the first-mentioned transducingresponse characteristic. The transducer device cent to the body for translating currents associated with the electrostatic-fieldsignal energy transduced in the body, and mechanical means for translating the motion associated with the =Jiexure during 'transducing, this flexure being associated with mechanical reaction between the -one portion of the body having the aforesaid sub- 3 stantial transducing-response characteristic and the other portion of the body. As will appear hereinbelow, the last-mentioned portion of the transducer body, which is of different composition from that of, and has a different transducing-response characteristic from that of, the first-mentioned portion, may have a substantially zero-valued transducing-response characteristic and thus may exhibit no appreciable electromechanical response except by mechanical reaction with the first-mentioned responsive portion.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the drawing, Figs. 1 and 2 are front and side elevations respectively of an electroded body useful in devices embodying the present invention; Fig. 3 is an enlarged sectional plan view of this body taken in the direction indicated 3, 3 on Fig. 2; Fig. 4 is a representative rough plot of the variation of the transducing properties of the body illustrated in section in Fig. 3 as a function of the thickness of the body as viewed in Fig. 3; and Fig. 5 is a perspective view of a transducer device in accordance with the present invention, this device comprising the body illustrated in Figs. 1-3 and being shown in association with apparatus, illustrated schematically, for use in a preliminary electrical conditioning of that body.

Referring now to Figs. 1 and 2 of the drawing, there is illustrated a thin body 2| substantially free of structural discontinuities, having one substantial portion, more specifically a thickness portion underlying and near the right hand major surface of the body, of a dielectric material, and having another substantial portion, more specifically a thickness portion underlying and near the left hand major surface, of a material of different composition. The body 2| may be designated as noncomposite, since it is not made up of two or more structurally distinct parts. A composite structure, on the other hand, is one made up of two or more distinct parts or elements with a pronounced interface therebetween. From a mechanical point of view the body 2| is substantially free of structural discontinuities, although it is recognized that the microstructure of the body may involve numerous crystalline grains having numerous interfaces but nevertheless forming essentially one structure as regards bending or twisting forces applied to the body within the elastic limits. On the other hand, it is clear that the composite elements of the prior art, constructed by cementing together two or more plates, have macroscopic interfaces. These interfaces constitute structural discontinuities, in which, due at least in part to imperfect adhesive properties of the cement used and to the different shear moduli of elasticity of the materials in the regions of the interfaces and elsewhere in the elements, a substantial fraction of the mechanical energy available during transducing may be lost.

Generally speaking, a difference in the composition of the material in two portions of the noncomposite body 2| may be realized in either of two ways. In one, the variation in composition through the body is a gradual one. In the other, materials of substantially different composition are present in neighboring portions of the body, but the molecular or crystal grain structure of the materials is so similar that the structural properties, determined at least to a large extent by the cohesive properties of the constituent materials and by their moduli of elasticity, are substantially unbroken throughout the body. If one of the conditions just mentioned is not met, an interface usually appears within the body and the noncomposite character of the body is destroyed. However, it should be understood that local imperfections of a small and scattered nature may appear, for example in the regions of greatest variation of the composition of the material, without destroying the essentially noncomposite nature of the body.

Electrodes 22 and 23 are aflixed to the body 2| in opposed positions adjacent respectively to the left hand and right hand major surfaces of the body, as viewed in Figs. 2 and 3. As illustrated, unelectroded margins are provided at the top and bottom of the body to facilitate mechanical connections to the body. The electrodes are shown with exaggerated thickness for ease of illustration. They may be made, for example, of conductive metal foil or of suitably bonded graphitic particles.

In the cross-sectional plan View of Fig. 3, the body 2| appears as a unitary member with the central plane of its thickness indicated by the center line 24. The body 2| has the shape of a plate or bar of small thickness compared with the other dimensions thereof. The one thickness portion of the body underlying the electrode 23 and disposed generally parallel to the major surfaces of the body is of a dielectric material, preferably a polycrystalline barium titanate material, which is conditioned by the application of a unidirectional electric potential to provide a substantial transducing-response characteristic as between mechanical signal energy and electrostatic-field signal energy. The other thickness portion of the body, underlying the electrode 22, is disposed generally parallel to and laterally of the aforesaid one portion and is of a dielectric material, preferably a polycrystalline dielectric material such as a modified barium titanate containing strontium titanate, which upon the application of the unidirectional potential as mentioned above has a transducingresponse characteristic as between the mechanical and electrostatic-field signal energies substantially different from the first-mentioned transducing-response characteristic of the one portion.

It should be noted here that the effective transducing response of a, portion of the body 2| may be determined in part by the distribution in the thickness direction of the body of the signal potentials, corresponding to the electrostatic-field signal energy in the body, which appear between the opposed electrodes 22 and 23. As a result of the differences in the composition of the materials making up the various portions of the body, this distribution may not be the same throughout the thickness of the body; in other words, the field strength may be different in different thickness portions of the body. Accordingly, for the purposes of this specification and the appended claims, it is convenient to define a transducing-response characteristic as the relationship between incremental mechanical energy per unit volume of the portion of the body under consideration and an incremental potential difference across the entire thickness of the body, the incremental potential difference being associated with an incremental electrostatic field energy per unit volume. It is assumedgrasz'ordinarily. is .the case,- that polarizing. andisignal'. electricrfi'eldsz arev applied in. the? thicknesszdirection of the body, but .'fields'.ma'yib e -ap'-- pliedx'across a larger dimension;

In: the manufacturev of bodies. of thetype de-"- scribed frompolycrystalline titanate materials; portions ofv the body maybe shapedcby methods. known generallyin theceramic arts. Thus a thin sheet. of. a dielectric material containing; primarily raw "barium. titanate-:may be formed by anyconventional method. After eventual ceramic firing, a sheet of suoha material-mayibacon dition'e'd. to provide' the desired response by. the application, whenever convenient andfoi' a pre determined period of time. of the order of a minute; of 'a unidirectional potential; The fired; material is susceptible to. remanent electrical. polarizatiom. which. persists. after: removal. of; the: unidirectional. polarizing. potential. Wherrrso polarized, this .material exhibits a .trans-ducing 're sponse characteristic which" notonly is of high: magnitude but also is substantially lineariover a reasonable amplituderange; This largelinear response probably depends both on the:ipola1'"iza tionzof the dielectric material. by the unidirectional voltage applied thereto andon the. propertiesofthe material before'polariz-ation. Another thin sheet of a dielectric material containing primarilya raw barium-strontiumtitanate may be formed.v in like manner. The two fiatsheets of unfired material are placed with a major sur.- face-of. each sheet in.mutu-al contact and. subjected to: a ceramic-firing. operation inwhich the interface between the two sheets. is eliminated as far as structural. properties are concerned by the incipient sintering' or vitrifying' actionwhich occurs-during ceramic firing. After polarization in a manner described hereinbelow, the resulting noncomposite body includes corresponding portions with substantial electromechanical transducing properties in the portion containing primarily barium titanate and substantially weaker transducing properties in the other portion. However, in View of the care which must'be taken to insure substantial elimination of the interface during firing, it is preferable to form asingle body of raw barium'titanate and treat this body. chemically" to modify the composition of the barium titanatematerial in'one'nortfon ofthe' bodyi Thus, the body may be modified'n'ear one major" face only by controlled amounts of a" material capable of reacting'with, orformin'g' a solid solution with, the barium titanate to 'form' in-a portion of the body a material which after ceramic'firing is not susceptible to appreciable remanent'electrical polarization upon the ap-- pli'cation for a predetermined period of the unidirectional polarizing potential, or which at least' i's su'sceptible to remanent electrical polarization of only a lower order of magnitude than the remanent polarization of the untreated barium titanate'material in the remainder of the body at ordinary temperatures of use; The portion of the'body so treated may exhibit no appreciable transducing-response characteristic, at'least in the absence of a continuously applied unidirectional potential of high intensity. A material which might be used for this purpose is strontium oxide, which is best used in the form of strontium titanate. The treatment may be carried out duringthe ceramic-firing operation, the material being applied to the side of the body being treat edxin:.finely. powdered form along with small amounts of a suitable flux; Duringthe firing:

the appliedimaterial: penetrates to a-;'.depth se tion of. the: barium titanate: material. canbe achieved, with? penetration. of. less material: into the titanazte body thanis the. case with. the strontium.- oxide material. Thus... modification of portions of the barium titanate materialby incorporation therein of severalpercent by Weight of stannic oxidegreatly decreases the abilityof that portion of the material to exhibit transducingI-response characteristics when the firedbody is conditioned. by the applicationof a unidirec tional polarizing potential. Whether. the m odie f-ying material. contains strontium ortin, smaller-' amounts of: modifying material may suifice: if, during or following a temporary application of a polarizing. field, the temperature of the body'is raised moderately to: remove remanent 'polarization in the portion .o'f the-body whose composition .has' been modified asdescribed above.- It the temperature 'remains below" about 1109' or 1'20 "C.,- the unmodified polarized barium titanate material retains all or most of its remanent polar ization;

The noncomposite electromechanically sensi tive body 2|: also maybe formed by dipping a backing structure successively into aqueous dispersions of'ba'rium titanate and barium strontium titanate-to form contiguous layers of thetwo' materials. This double-dipping process is dis-- closed and claimed in an application for Letters Patent of' the United States, Serial No. 67,695} filed concurrently herewith in the" name of Charles Gravley' and assigned to the same assignee as the'present' invention; which issued onSeptember 25, 1951, as PatentNo; 2,569,163! The body formed by this double-dipping opera tion then is subjected to ceramic-firing tem-- p'eraturesto establish a ceramic bond'betw'een the two layers which is substantially asstrong as the bonds within the individual layers and of substantially similar elastic properties.

A plate-like body substantially free of structural discontinuities, formed by one of the meth-- ods suggested hereinabove, has'portions of different compositions differing substantiallyin their electromechanical transducing properties. At least the portions of this body which have relatively high values of the local .el'ectro-- mechanical transducing properties are'of adielectr-ic material, and in the examples mentioned hereinabove all portions of the bodyare of dielectric materials; Transducer bodies freeof. structural discontinuities and containing one portion of a dielectric material and anotherportion of a conductive material are described and claimed in the aforementioned copending application of Hans G. Baerwald. Often it is: convenient to form the portions of difierent compositions so that these portions have equal thicknesses. Then one portion lies generally to one side of the centerline 24, Fig. 3, while therother" portion lies generally to the other side. In the region of the central plane the composition may change more or less abruptly in the thickness direction, but without any abrupt change in the structural properties of the material. However, it may be desirable to make one portion considerably thicker than the other. For example, the portion having a transducing-response characteristic of greater value may be thinner than the relatively unresponsive portion. In such a case a chemical treatment for modifying the composition of the body near one side thereof might become impractical, and it is recommended that the body be formed by the method of the aforementioned copending Gravley application. Some of the considerations which determine the optimum relative thicknesses of the two portions of the body are discussed in the aforementioned copending Baerwald application.

When the two layers of the body 2| have approximately equal thicknesses but have different transducing-response characteristics upon conditioning by a polarizing potential, the transducing properties of the body may be represented in a rough manner by the plot of Fig. 4. This plot is aligned vertically below the transverse sectional view of Fig. 3 so that the thickness coordinate of the plot coincides with the thickness direction in the body as viewed in Fig. 3. The plot of Fig. 4 may represent roughly the variation of the transducing properties through the thickness direction when the left hand portion of the body is a barium-strontium titanate material and the right hand portion is polarized barium titanate material. In this case only the right hand portion has substantial transducing-response characteristics, and the transducing properties of the regions of the body near the left hand major surface have zero values. In this connection it appears from the above that the different polarization of the left hand portion advantageously is a polarization of a lower order of magnitude than the polarization of the right hand portion, with a corresponding transducing-response characteristic of a lower order of magnitude than that of the right hand portion. In the case where the material of the left-hand portion has a lower or residual, but substantial, local response, it will appear that a transducing property represented along the vertical coordinate in the plot of Fig. 4 would have a zero value below the plotted curve, as at A0. As a matter of fact, if the left hand portion is a barium-strontium titanate of the 70:30 mole ratio mentioned hereinabove, when a preliminary polarizing field has been applied and removed, the different polarization of the left hand portion actually is zero with a negligible transducing-response characteristic therein, since this material does not retain remanent polarization. In this case it appears that the local transducing properties in the regions near the left hand surface have zero value, as indicated at B in Fig. 4:. In both cases the two portions of the body just underlying its two major surfaces are of materials providing the extremes of values of transducing-response characteristics in the body, which is a condition conducive to efficient bending response of the body during transducing. The mechanism of the bending response, involving mechanical reaction between portions of the body having different values of the electromechanical transducing properties, will be explained in greater detail hereinbelow. Any of various local transducing properties-might be plotted to 8 obtain the curve of Fig. 4; The transducingresponse characteristic as defined hereinabove may be used. In this case, for example, after polarization of the body 2| by the application of a high unidirectional voltage across the electrodes in the thickness direction, the mechanical effect of the electric signal field resulting from the application of unit voltage across the electrodes is plotted for small volume portions of the body. The mechanical eiTect may be expressed in terms of the fractional or percentage distortion or strain in a direction lengthwise of the body, since this type of strain is associated with the desired bending response.

A complete transducer device which is electromechanically sensitive to fiexure is illustrated in Fig. 5. The device includes the body 2| and its electrodes, electrical circuit terminals 25 and 26 connected to the electrodes 22 and 23 respectively, a base 2'! in which the lower end of the body 2| is mounted securely, a yoke 28 secured to the top of the body 2|, and a rod 29 projecting horizontally from the yoke 28 for providing mechanical coupling to the device.

For use in the initial polarization of the body 2| a unidirectional high voltage source 30 may be connected to the terminals 25 and 26, for example through a double pole switch 35. This connection may be made before or after the complete transducer device represented in Fig. 5 is assembled, and the switch 35 may be closed for a short period of time toprovide the transducing properties represented by the plot of Fig. 4. A polarizing potential approaching the breakdown voltage of the material may be used, although lower polarizing potentials often are entirely adequate. The polarizing connections to the terminals 25 and 28 then may be removed and used in polarizing other transducer bodies. However, if the body should lose its polarization for any reason, for example by inadvertent heating above C., the polarizing arrangement easily may be employed again to restore the desired transducing properties.

In operation, the device of Fig. 5 may be used to transduce from electrical energy to mechanical energy or vice versa. In either case, suitable electrical and mechanical means, not shown, are connected to the electrical- circuit terminals 25, 26 and to the mechanical-coupling rod 29, respectively, to serve as source means or utilization means for the energy transduced, as the case may be. Accordingly, the device comprises means including the electrodes 22, 23 and the terminals 25, 26 for translating currents associated with the electrostatic-field signal energy transduced in the body. Furthermore, the yoke 28 and rod 29 constitute mechanical means for translating the motion associated with the flexure of the body 2| during transducing. Thus a bending flexure of the body is associated with mechanical reaction between the right hand'portion having the substantial transducing-response characteristic and the left hand portion of the body. Application of a signal potential acros the terminals 25 and 26 causes the more responsive right hand thickness portion to expand or contract, resulting in a net bending motion by mechanical reaction with the opposed thickness portion having negligible electromechanical response. The bending motion is translated by longitudinal motion of the rod '29 in the direction of the double arrow, Fig; 5. Conversely, moving the rod 29 longitudinally causes a. bending of lines extending vertically in the de- 9:5 vice',rresulting.rinztheiappearancc'xofrasignalipow tentia'l across thewterminals. i

Under some. circumstances; t for; irexample :io'r. operation athighfltemperaturesoriwith high-elecs tric signalpotentials, it'imayzbez:desirable.to;main-' tain-the" unidirectional voltage source: of.'. Fig;Z.5 1 connected" to the transducer: body: during: operation.: 1 With such continuous: polarization thesre-: sponse of :a barium: titanate V material; is: higher:v than-with remanent'ipolarization;. The unrespon sive portion 'ofi the body thent-"advantageously is r a abarium-titanate containing :bariumi'zstannate, which may be introduced-by treatment with. stannic i oxide: as mentioned: 7 hereinab'oven The rel-:7 sponse of the modified titanate :is-muchi le'ss:.than: that' of 1 the barium titanate; even underts a :con-:-' tinuously applied polarizing field.

It is advantageous that the ielectromechanically unresponsive portionof the. body 2 lf,th'at1is;:ithei left' handportion asrepresentedin FigSI'B an'di'- Y be of adielectric material :of -'a':composition .WhiCh'i' has-a higher dielectric constantzzthan that :ofz th material: 'of th'e: more responsivaporti'on.ate-pre determined operatingtemperatures; such as item: peratu-res between" "and. 100 For example; a barium strontium titanate may' havesa dielectrici constant 3 or 4 times thatof barium2titanate, whil "-barium titanate containing several iweight percent- 0f stannic oxide may have-a dielectric constant 'about twice that- 0f the unmodified barium 'tit'anate.- When the electromechanicallyi unresponsive-portion-has a higher dielectric conT- stant, the-several portions of the -bodyi'acte as a.; vo1tage=divider-made up of series capacitances: An electric potential appearing 8.Cl'0SS th'-e1ltlr body 'then'=-'is associated with "ahigher-" fie'ld' strength in the electrom'echanically responsive portion, increasing the transducing efficiency.

While" there have' been described what-areat presentconsid'eredto be the preferred emb'o'di ments-of'this invention, it willbeobviousto'those skilled in the-art that various changes and modifications-maybe madetherein without departing from "the'in'vention', and it is, therefore; aimed in the appended claims'to cover all-"such'changes' and' modifications as fall within the true spirit and scope of the invention.

Whatis claimed'is:

1; 'Ai' transducerdevice electromechanically sensitive =to fiexure comprising:- a' body substantially' free of structural discontinuities.- having one substantial portion of a dielectric materi'alwvhich is conditioned by" the application of a unidirectional electric potential to provide a substantial transducing-response characteristic as between mechanical signal energy andelectrostatic-field' signal' 'energy, and having another substantial portion -0f a'dielectric material ordifferent composition which u on said application of said unidirectionalpotential: hasa transducing-res-ponse characteristic as-between saidsi'gnal'energies sub stantiallydifierent from f said first mentioned 1o: thereof, substantially free of structural discontinuities, having one-substantial thickness portion disposed-generally parallel to the major surfaces of said body and of a dielectric material which is conditioned by'the application of a unidirectional electric potential to provide a substantial transducing-response characteristic as between mechanical signal energy and electrostatic-field signal energy, and having another substantial thickness portion disposed generally parallel to and laterally of said one portion and of a dielectric material of difierent composition which upon said application of said unidirectional potential has a transducing-response characteristic as between said signal energies substantially *diiierent' from said first-mentioned charac-teristic;'means for translating currents associated with said electrostatic-field signal energy transduced in said body, including electrodes in opposed positions adjacent to said major surfaces of said body and between which signal potentials corresponding to said electrostaticfieldsignalenergy may appear; and mechanical means for translating the motion associated with said flexure during transducing, said flexure being associated with mechanical reaction between said one portion having saidsubstantial transducing-response characteristic and said other portion of said body.

3. A transducer device electromechanically sensitive to flexure comprising: a thin body substantially free of structural discontinuities, having near'one of the major surfaces of said body one-' substantialportion of a dielectric material which is conditioned by the application of a unidirectional electric potential to provide a substantial transducingerespon'se characteristic as between mechanical signal energy and electrostatic-field'signal'energy, and having-near the othermajor surface'of said body another substantialrportion of a dielectric material of difierent composition which upon said application of said unidirectional potential is effective to provide'a transducing-response characteristic as between said'signalenergies substantially different from said first-mentioned characteristic, said one and said otherportions being of materials providing-the extremes of values of transducing-response characteristics in said body; means for translatingicurrents associated with said electrostatici-fieldi'energytransduced in said body, including electrodesin opposed positions adjacent to said-major'surfaces'of said body and between which signal potentials corresponding to said electrostatic fieldsignalenergy may appear; and mechanicalmeans for translating the motion associated with said fiexure during transducing, said r'lexure being associated with mechanicalreaction betweensaid one portion having said substantialtransducing-response characteristic and other portions of said body.

4. A transducer device electromechanically sensitive to flexure comprising: a body subs-tantiallY-ireeofstructural discontinuities, having one substantial portion of a polycrystalline titanate dielectric material which is conditioned by the application of a unidirectional electric potential'to provide'a substantial transducingresponsecharacteristic as between mechanical signal energy and electrostatic-field signal energy; and having another substantial portion of a dielectric-material of diiierent composition which upon said application of said unidirectional-potentialhasa transducing-response characteristicas between said signal energies substantially difierent from said first-mentioned characteristic; means including electrodes adjacent to said body for translating currents associated with said electrostatic-field signal energy transduced in said body; and mechanical means for translating the motion associated with said flexure during transducing, said fiexure being associated with mechanical reaction between said one portion having said substantial transducingresponse characteristic and said other portion of said body.

5. A transducer device electromechanically sensitive to flexure comprising: a body substantially free of structural discontinuities, having one substantial portion of a polycrystalline barium titanate material which is conditioned by the application of a unidirectional electric potential to provide a substantial transducingresponse characteristic as between mechanical signal energy and electrostatic-field signal energy, and having another substantial portion of a polycrystalline dielectric material of different composition which upon said application of said unidirectional potential has a transducingresponse characteristic as between said signal energies substantially different from said first-mentioned characteristic; means including electrodes adjacent to said body for translating currents associated with said electrostatic-field signal energy transduced in said body; and mechanical means for translating the motion associated with said fiexure during transducing, said flexure being associated with mechanical reaction between said one portion having said substantial transducingresponse characteristic and said other portion of said body.

6. A transducer device electromechanically sensitive to fiexure comprising: a body substantially free of structural discontinuities, having one substantial portion of a polycrystalline barium titanate material which is conditioned by the application of a unidirectional electric potential to provide a substantial transducing-response characteristic as between mechanical signal energy and electrostatic-field signal energy, and having another substantial portion of a polycrystalline titanate dielectric material of different composition which upon said application of said unidirectional potential has a transducing-response characteristic as between said signal energies substan tially different from said first-mentioned characteristic; means including electrodes adjacent to said body for translating currents associated with said electrostatic-field signal energy transduced in said body; and mechanical means for translating the motion associated with said flexure during transducing, said flexure being associated with mechanical reaction between said one portion having said substantial transducing-response characteristic and said other portion of said body.

'7. A transducer device electromechanically sensitive to fiexure comprising: a body substantially free of structural discontinuities, having one substantial portion of a dielectric material which is susceptible to remanent electrical polarization to provide a substantial transducing-response characteristic as between mechanical signal energy and electrostatic-field signa1 energy, and having another substantial portion of a dielectric material of a different composition which is susceptible to remanent electrical polarization of only a lower order of magnitude than said remanent polarization of said dielectric material of said one portion to provide a transducing-response characteristic as between said signal energies lower in magnitude than said first-mentioned characteristic; means including electrodes adjacent to said body for translating currents associated with said electrostatic-field signal energy transduced in said body; and mechanical means for translating the motion associated with said flexure during transducing, said flexure being associated with mechanical reaction between said one portion having said substantial transducing-response characteristic and said other portion of said body.

8. A transducer device electromechanically sensitive to fiexure comprising: a body substantially free of structural discontinuities, having one substantial portion of a dielectric material which is conditioned by the application of a unidirectional electric potential to provide a substantial transducing-response characteristic as between mechanical signal energy and electrostatic-field signal energy, and having another substantial portion of a material of a different composition which has a higher dielectric constant than that of the material of said one portion at predetermined operating temperatures and which upon said application of said unidirectional potential has a transducing-response characteristic as between said signal energies of a lower order of magnitude than said first-mentioned characteristic; means including electrodes adjacent to said body for translating currents associated with said electrostatic-field signal energy transduced in said body; and mechanical means for translating the motion associated with said flexure during transducing, said flexure being associated with mechanical reaction between said one portion having said substantial transducing-response characteristic and said other portion of said body.

9. A transducer device electromechanically sensitive to fiexure comprising: a body substantially free of structural discontinuities, having one substantial portion of a dielectric material which is susceptible to remanent electrical polarization to provide a substantial transducing-response characteristic as between mechanical signal energy and electrostatic-field signal energy, and having another substantial portion of a dielectric material of a different composition which has a higher dielectric constant than that of the material of said one portion at predetermined operating temperatures and which is susceptible to remanent electrical polarization of only a lower order of magnitude than said remanent polarization of said dielectric material of said one portion to provide a transducing-response characteristic as between said signal energies substantially lower in magnitude than said first-mentioned characteristic; means including electrodes adjacent to said body for translating currents associated with said electrostatic-field signal energy transduced in said body; and mechanical means for translating the motion associated with said flexure during transducing, said fleXure being associated with mechanical reaction between said one portion having said substantial transducing-response characteristic and said other portion of said body.

10. A transducer device electromechanically sensitive to flexure comprising: a body substantially free of structural discontinuities, having one substantial portion of a dielectric material containing primarily barium titanate which is susceptible to remanent electrical polarization to provide a substantial transducing-response characteristic as between mechanical signal energy and electrostatic-field signal energy, and

having another substantial portion of a dielectric material containing primarily a barium-strontium titanate riot susceptible to appreciable remanent electrical polarization to provide a transducing-response characteristic as between said signal energies substantially lower in magnitude than said first-mentioned characteristic; means including electrodes adjacent to said body for translating currents associated with said electrostatic-field signal energy transduced in said body; and mechanical means for translating the motion associated with said flexure during transducing, said fiexure being associated with mechanical reaction between said one portion having said substantial transducing-response characteristic and said other portion of said body.

11. A transducer device electromechanically sensitive to fiexure comprising: a body substantially free of structural discontinuities and having polycrystalline dielectric portions of different compositions, including one portion containing primarily barium titanate with substantial electromechanical transducing properties and another portion containing primarily a bariumstrontium titanate with substantially weaker electromechanical transducing properties and a higher dielectric constant than that of the material of said one portion at predetermined op erating temperatures; means including electrodes adjacent to said body for translating currents associated with electrostatic energy transduced in said body; and mechanical means for translating the motion associated with said flexure during transducing, said fiexure being associated with mechanical reaction between said one portion having said substantiial electromechanical transducing properties and said other portion of said body.

HARRY C. PAGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 355,149 Dolbear Dec. 28, 1886 1,803,274 ,Sawyer Apr. 28, 1931 2,338,242 Arndt Nov. 6, 1945 ,394,670 Detrick Feb. 12, 1946 25 2,402,515 Wainer June 18, 1946

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