Abstract: A body of polymeric piezoelectric material is nonuniformly poled by: applying an electric field across the thickness of the body, from one surface to another surface, of a strength sufficient to induce nonuniform polarization in the material; and reversing the polarity of the poling field, thereby increasing the nonuniformity. In a preferred embodiment, the material is poled at an elevated temperature; the poling field is of sufficient strength such that a portion of the body near one surface is polarized in one direction and a portion of the body near the other surface is polarized in a substantially opposite direction; and the polarity of the poling field is reversed a plurality of times.A flexure element comprising a continuous body of polymeric piezoelectric material nonuniformly poled according to the method of the present invention, exhibits strong flexure response to applied fields.

Abstract: The invention relates to piezoelectric and pyroelectric transducers whose active element is formed by a polymer film. The invention provides a process for manufacturing a transducer from a flat polymer film which consists in stretching this film over a mold so as to give it a self-supporting form and to electroform this film by means of a corona discharge.

Abstract: A feedback circuit for use in an oscillator has a piezoelectric oscillating unit constituted by a square plate-like piezoelectric body, first and second electrodes provided on one surface of the piezoelectric body and a common electrode provided on the other surface of the piezoelectric body. The piezoelectric body is polarized in one direction between the first and common electrodes and in the opposite direction between the second and common electrodes.

Abstract: A flexural electromechanical transducer composed of a constant-modulus alloy material and a piezoelectric ceramic material having a high electromechanical coupling coefficient. In the transducer, the piezoelectric ceramic material is polarized in one direction and a specified frequency signal is applied to the piezoelectric ceramic material in a direction parallel to the residual polarization direction of the piezoelectric material for obtaining a thickness-shear vibration. The thickness-shear vibration of the piezoelectric material in turn causes the flexural vibration of the transducer. The transducer achieves a high quality factor Q, a low capacitance ratio r, good spurious characteristics, and low impedance.

Abstract: An apparatus for checking the direction of polarization of shear-wave ultrasonic transducers comprises a first planar surface for mounting the shear-wave transducer, a second planar surface inclined at a predetermined angle to the first surface to generate longitudinal waves by mode conversion, and a third planar surface disposed at a second predetermined angle to the first for mounting a longitudinal-wave ultrasonic transducer. In an alternate embodiment, two second planar surfaces at the predetermined angle are placed at an angle to each other. The magnitude of the shear wave is a function of the angle between the direction of polarization of the transducer and the mode-conversion surface.

Abstract: A monolithic crystal filter is disclosed that provides much wider bandwidths than were obtainable by prior art crystal filters. The inventive wide-bandwidth monolithic filter includes a piezoelectric substrate, an output electrode, a plurality of input electrodes arranged in orthogonal relationship with the output electrode and common electrodes disposed opposite to the input and output electrodes. The input and output electrodes are preferably disposed on the substrate along the crystallographic axes thereof. Increased bandwidth is realized due to the increased coupling resulting from the combination of the individual couplings from each input electrode at the outputelectrode. As a result of the increased coupling provided by the inventive crystal filter, overtone mode operation is now possible at much higher frequencies which heretofore were not obtainable by prior art crystal filters due to impractically close electrode spacing requirements.

Abstract: Organic piezoelectric elements having a piezoelectric modulus of the order of as high as 10.sup.-6 c.g.s.e.s.u. or more are obtained from a film, sheet or other shaped structure of a high molecular weight copolymer of 99 to 50% by weight of vinylidene fluoride with, correspondingly, 1 to 50% by weight of a comonomer, by heating the shaped structure to a temperature of 40.degree. to 200.degree. C. in an electrostatic field of an electropotential gradient of 30 to 1,500 KV/cm.

Abstract: An intrusion sensor uses thin film piezoelectric transducers to sense nea mechanical vibrations. A hose-like sheath contains a pair of insulating strips which carry conductive leaves on their outer surfaces. A series of longitudinally arranged segments of a thin film piezoelectric material are coupled to the leaves to provide signals representative of impinging mechanical vibrations. Since adjacent ones of the thin film segments are alternately polarized, signals are created only when the vibrations are nearby. Greater sensitivity to nearby vibrations is assured when each of the segments is fabricated from several layers of the thin film piezoelectric material.

Abstract: Material suitable for a surface acoustic wave device comprises an epitaxial film of aluminum nitride on the surface of a substrate of single crystal aluminum oxide, said surface having the crystallographic orientation 1100.

Abstract: A method and apparatus for processing piezoelectric bodies to have a permanent polarization for use as electroacoustic transducers or the like are described. During the application of a constant polarizing electric field to a piezoelectric body, the surfaces of the body, which for example, might be in the shape of a disc, have applied thereto a surface pressure. A clamping device having smooth surfaces is used for this purpose.

Abstract: A transducer of the type converting between electrical and mechanical energy by means of the piezoelectric effect in a supported sheet of uniaxially oriented, electrically polarized thin high polymer film such as polyvinylidene fluoride, having surface electrodes thereon for connection to an electrical circuit. The transducer is characterized by an arrangement of the piezoelectric film into a series of elongate curved cylindrical segments of alternating sign of curvature, with the surface electrodes on the film being divided in selected locations between adjacent segments. A useful level of elastic stability is achieved without using a static pressure difference on the film, good electromechanical coupling is attained, and the individual transducer elements formed by the divided surface electrodes may be usefully interrelated electrically to substantially cancel even order harmonic distortion and enhance linearity of operation.

Abstract: This disclosure is directed to an electro-optic cell construction of the type which employs a layer of minute dipole particles in a suspension carried between two transparent sheets for use as an electro-optic light controlling device such as a shutter, or the like. In combination with the dipole particle containing fluid chamber are optically transparent piezoelectric transformer elements for causing a transverse electric field in the fluid chamber to increase the speed of response of the shutter action.