Abstract: A transducer apparatus is disclosed having a spool member with a body portion and first and second elevated regions formed on the body portion. A PVDF film surrounds the spool member, the film including an inner surface facing the spool member and an outer surface opposite the inner surface. The film as surrounding the spool member has a predetermined frequency of resonance. Lateral ends of the film are secured together by a securing material. The securing material is such that the secured ends of the film will have substantially the same resonance frequency as a remainder of the film. The film includes a non-electrode area at a perimeter of the inner surface and an electrode material formed on a remainder of the inner surface. Upon securing the lateral edges of the film together, the securement is at overlapping non-electrode lateral edges of the film. The securing material may be any one of an adhesive in combination with screws or thermally deformable nails, adhesive alone, tape, or ultrasonic welding.

Abstract: A method of forming an ultrasound transducer having thermoformed protuberances comprises providing a substrate having a plurality of perforations of a given dimension. The perforations or apertures are formed in the substrate and operate to determine the resonance frequency associated with the transducer. A film of polymeric material capable of showing piezoelectric properties when strained in its plane and electrically biassed by a field applied in a direction normal to its faces, is then laminated onto the substrate. The film is heated to a given temperature and a pressure differential is applied between the top and bottom surfaces of the film for a sufficient time to form protuberances in the film through the apertures in the substrate.

Abstract: A resonant-type transducer providing a narrow band, high output or high sensitivity signal to a radiation medium, the resonant transducer comprising a vibrator body comprising piezoelectric or electrorestricitive material having a first acoustic impedance at a resonant condition, and a matching layer for acoustically matching the piezoelectric vibrator body at resonance to the radiation medium.

Abstract: The object of the invention is to provide a method for molding a resin-molded article having an excellent surface appearance without any resin-intrusion part on the front surface of a skin thereof. In the invention, the skin is placed on a part of a inner wall of a mold and then injecting a synthetic resin into a cavity of the mold to effect an integral molding of a resin-molded article having the skin on a part thereof, wherein a mold having a first gate on a first inner wall part located on the part other than the back surface of the skin placed on the inner wall of said mold and a second gate on a second inner wall part which faces the back surface of the skin placed on the inner wall is employed; and wherein the synthetic resin is first injected from said first gate until the tip portion of the synthetic resin comes close to the edge of said skin, and then the synthetic resin is injected from the second gate.

Abstract: A method of forming an ultrasound transducer having thermoformed protuberances comprises providing a substrate having a plurality of perforations of a given dimension. The perforations or apertures are formed in the substrate and operate to determine the resonance frequency associated with the transducer. A film of polymeric material capable of showing piezoelectric properties when strained in its plane and electrically biassed by a field applied in a direction normal to its faces, is then laminated onto the substrate. The film is heated to a given temperature and a pressure differential is applied between the top and bottom surfaces of the film for a sufficient time to form protuberances in the film through the apertures in the substrate.

Abstract: A resonant-type transducer providing a narrow band, high output or high sensitivity signal to a radiation medium, the resonant transducer comprising a vibrator body comprising piezoelectric or electrorestricitive material having a first acoustic impedance at a resonant condition, and a matching layer for acoustically matching the piezoelectric vibrator body at resonance to the radiation medium.

Abstract: The object of the invention is to provide a method for molding a resin-molded article having an excellent surface appearance without any resin-intrusion part on the front surface of a skin thereof. In the invention, the skin is placed on a part of a inner wall of a mold and then injecting a synthetic resin into a cavity of the mold to effect an integral molding of a resin-molded article having the skin on a part thereof, wherein a mold having a first gate on a first inner wall part located on the part other than the back surface of the skin placed on the inner wall of said mold and a second gate on a second inner wall part which faces the back surface of the skin placed on the inner wall is employed; and wherein the synthetic resin is first injected from said first gate until the tip portion of the synthetic resin comes close to the edge of said skin, and then the synthetic resin is injected from the second gate.

Abstract: A transducer apparatus is disclosed including a spool member having a body portion and first and second elevated regions formed on the body portion. A piezoelectric film such as a PVDF film surrounds the spool member and is spaced apart from the body portion of the spool member by an elevation of the elevated region, thereby forming a predetermined gap between the piezoelectric film and the body portion of the spool member. The predetermined gap is at least 0.1 mm and enables a predetermined resonance frequency in the piezoelectric film to control the resonance frequency of the transducer. Opposite lateral ends of the piezoelectric film are secured together such that secured ends of the piezoelectric film have substantially the same resonance frequency as a remainder of the piezoelectric film.

Abstract: A touch sensitive switch is fabricated from a substrate having a touch region on a first surface and a piezoelectric element on a second surface of the substrate. The piezoelectric element is driven by a signal configured so that an ultrasonic wave generated by the element is transmitted into the substrate and is reflected back and forth into the substrate at both surfaces. A touch changes the reflectivity at the first surface, and influences the impedance of the transducer assembly which is comprised of the piezoelectric element and the substrate.

Abstract: An electroacoustic transducer assembly which comprises multiple layers of piezoelectric polymer material on an acousto-reflective support member. The inner layer closest to the support member is excited at a fixed frequency and the overall thickness of the multiple layers is about one quarter of the wavelength of the wave of fixed frequency within the layers. In a variation of this structure, the inner layer is subdivided into a plurality of thin layers which are excited with alternating polarities.

Abstract: A transducer assembly for a proximity sensor which comprises an elongated polymer piezoelectric film (16). The film is supported as an elongated series of arcuate segments which are curved in the same direction and have the same radius of curvature. Electrodes (18) on both sides of the piezoelectric film form opposed pairs, each pair being associated with a respective arcuate segment. The electrodes are utilized for applying a varying electric field across the thickness of the film to cause an ultrasonic acoustic wave to be radiated from the film.

Abstract: An ultrasonic proximity sensor particularly suited for outdoor environments having a transducer including a polymer piezoelectric film bonded to a protective metal layer. The transducer is mounted in the sensor housing so that the protective metal layer is exposed to the environment through a window of the sensor housing. The transducer can be implemented as an asymmetric bimorph structure, having an electrode bonded to a surface of the polymer piezoelectric film opposite the protective metal layer and between support members. Deformation of the polymer piezoelectric film between the protective metal layer and the electrode occurs upon application of a voltage thereto, generating an ultrasonic wave. The transducer can also be used as a receiver, generating an output voltage from the electrode upon impingement of an ultrasonic wave upon the protective metal layer.

Abstract: A short distance ultrasonic distance meter is disclosed with provisions to reduce the ill-effects of ringing when measurements are of obstacles closer than about ten inches. In one embodiment an opposite phase ultrasonic wave is introduced by a circuit (245) and in another embodiment a strain sensor (232) introduces negative feedback to effect cancellation of ringing (147). Finally, in a third embodiment, both the negative feedback and opposite phase methods are employed for optimal results.

Abstract: An ultrasonic distance meter cancels out the effects of temperature and humidity variations by including a measuring unit and a reference unit. In each of the units, a repetitive series of pulses is generated, each having a repetition rate directly related to the respective distance between an electroacoustic transmitter and an electroacoustic receiver. The pulse trains are provided to respective counters, and the ratio of the counter outputs is utilized to determine the distance being measured.

Abstract: An electronic article surveillance system including a bulk acoustic wave transponder 10 coupled to an antenna 12, an interrogator 14, directional antenna 16 and an output connector 18. The transponder comprises a silicon or glass substrate 20, bus electrodes 22, 24, a launching IDT T0 and a series of "connected" and "unconnected" IDTs T1-T4. The connected/unconnected state of the respective IDTs T1-T4 may be detected and employed to generate an identification code comprising a series of binary digits. A thin copolymer piezoelectric film 26 covers the substrate 20 and electrodes T0-T4.

Abstract: A wideband ultrasonic transducer comprises at least two stretched piezoelectric polymer films rolled together in a lengthwise direction so as to form a scroll having an axis parallel to a stretch direction of the polymer films. Each of the polymer films has a different width W in a longitudinal direction of the scroll, where the widths W are related to respective acoustic wavelengths .lambda. of the polymer films. A resonant frequency of each polymer film is selected by varying the widths W of each polymer film and the resonant frequencies of the polymer films are preferably selected so as to occupy a desired contiguous frequency band. An electric field is applied to each of the polymer films in parallel so as to induce expansion or shrinkage of the polymer films in their stretched directions, thereby causing resonance at their respective resonant frequencies.

Abstract: A two-dimensional laser beam scanning device having a support base and a piezoelectric bimorph structure comprising four consecutively bonded piezoelectric layers disposed in the support base. The two outer layers of the bimorph structure have a shorter length than the two inner layers, and the inner two layers extend lengthwise in one direction past the ends of the outer two layers to form a two-layer bimorph portion having a free end. The four-layer portion is affixed along a first lengthwise edge thereof to the support base. The other lengthwise edge defines a free edge. The free end of the two-layer portion is bent ninety-degrees. The two-layer portion has a different resonant frequency than the four-layer portion.

Abstract: A surface emitting grating is coupled to an optical amplifier and has grating elements tilted non-normal relative to the amplifier optical axis. The angle of tilt in one embodiment is such that the grating reflections are refracted out of the amplifier region. The amplifier may have a tilted light receiving end serving as an input port in a second embodiment to cause internal reflections from the grating to be reflected to an amplifier boundary at an angle greater than the critical angle to cause the reflections to pass out of the amplifier region. In the latter embodiment, the grating tilt angle is minimized to reduce the surface emission beam angle tilt from the normal to a relatively small angle.

Abstract: The frequency response of a component whose output decreases past a first frequency is extended by employing apparatus which provides for a signal source to be coupled to a component transmission line through a coupling impedance of about zero. The transmission line is resonant at a second frequency greater than the first frequency and the characteristic impedance of the transmission line is selected such that the voltage drop at or near direct current across the component is about equal to the voltage drop across the component at the second frequency. The method of operation comprises providing a signal, forming a transmission line which is resonant at the second frequency and coupling the transmission line to both the component and the signal source. The characteristic impedance of the transmission line is adjusted such that the voltage across the component at or near direct current is about equal to the voltage across the component at the second frequency.

Abstract: A signal processing apparatus and method extend the frequency response of a component whose output decreases past a first frequency. The apparatus responds to a signal having a range of frequencies which is applied to a component transmission line and the component transmission line is coupled to the component. The component transmission line is resonant at a second frequency greater than the first frequency and has a source impedance and an input impedance which are not matched. The source impedance is greater than the impedance of the component. The method comprises providing a signal, forming a transmission line which is resonant at the second frequency and coupling the transmission line to both the component and the signal source. The source impedance is adjusted such that the voltage across the component at a low frequency limit is about equal to the voltage across the component at the second frequency.