Abstract: A speaker device for emitting subsonic, sonic or ultrasonic compression waves comprising a generally hollow drum, a rigid emitter plate attached to the drum, and a plurality of apertures formed within the plate which are covered by a thin piezoelectric film disposed across the emitter plate. A pressure source is coupled to the drum for developing a biasing pressure with respect to the thin film at the apertures to distend the film into an arcuate emitter configuration capable of constricting and extending in response to variations in the applied electrical input at the piezoelectric film to thereby create a compression wave in a surrounding environment. Parametric ultrasonic frequency input is supplied to the piezoelectric film to propagate multiple ultrasonic frequencies having a difference component corresponding to the desired subsonic, sonic or ultrasonic frequency range.

Abstract: A digitizer uses acoustic waves originating from a stylus to determine the position of the stylus on a plate. The acoustic waves are introduced into the plate from the tip of the stylus and are detected by a plurality of detectors positioned at various points along the periphery of the plate. By sensing differences in the arrival times of the acoustic waves at the detectors, a microprocessor calculates the position of the stylus. In a preferred embodiment using a non-tethered stylus, four detectors are positioned at the corners of a rectangle, and the time differences are used as addresses in a lookup table, which is programmed to contain x and y coordinates corresponding to the time differences, Different embodiments may detect only the "fast" symmetrical waves or only the "slow" antisymmetrical waves generated in the plate, or may use the arrival times of both types of waves to determine the stylus position.

Abstract: An ultrasound therapy system and method for providing therapeutic treatment to tissues using multiple, user-selectable frequencies generated from a single applicator sound head. The multi-frequency ultrasound therapy system and method includes a generator/control unit having a microprocessor for controlling and monitoring the generation and output of ultrasonic energy. A precision oscillator is connected to the microprocessor, and wave shaping circuitry is also provided to generate a wave-form for amplification by an output amplifier. The amplified high frequency wave-form is supplied to and drives an applicator sound head at an appropriate frequency for producing the desired therapeutic ultrasonic waves for treatment. Bonded to a cup member and positioned within the applicator sound head is a transducer crystal which converts high frequency wave-forms into mechanical (acoustic) vibrations, thus producing thermal energy in the form of heat for penetration into tissues under treatment.

Abstract: A hydrophone for calibrating lithotripters includes a spot poled disc of piezoelectric material which is mounted on a brass cylinder backing. A coaxial cable is electrically connected to one surface of the disc through the brass backing and the opposing surface of the disc. A mixture of polymeric material and microballoons is provided to protect the interconnection of the center conductor and the opposing surface of the disc and prevent damage due to the incident ultrasonic shock waves. The brass backing is placed in a suitable housing of phenolic material. A process in fabricating the piezoelectric disc and assembling the hydrophone is disclosed.

Abstract: An acoustical lens for focusing ultrasonic energy having a transducer, a curved focussing lens and a voltage generator coupled with the transducer. The transducer is comprised of an array of piezoelectric crystal elements. The focussing lens has a concave upper surface and a planar bottom surface allowing the array of piezoelectric elements to be coupled to the bottom surface of the array. The piezoelectric elements receive voltage from the voltage generator and transmit an energy ray through the focussing lens producing a focussed energy beam.

Abstract: An acoustical lens for focusing ultrasonic energy having a transducer, a curved focussing lens and a voltage generator coupled with the transducer. The transducer is comprised of an array of piezoelectric crystal elements. The focussing lens has a concave upper surface and a planar bottom surface allowing the array of piezoelectric elements to be coupled to the bottomsurface of the array. The piezoelectric elements receive voltage from the voltage generator and transmit an energy ray through the focussing lens producing a focussed energy beam.

Abstract: Apparatus for use in cannulation of blood vessels includes a hollow needle having a sharpened end for penetrating tissue, a trocar including a transducer mounted on one end for positioning within the hollow needle for transmitting and receiving ultrasonic waves through the sharpened end of the needle. The trocar further includes a support rod for the transducer and ultrasound damping material attaching the transducer to the support rod. Electrical conductors are provided through the support rod or on the surface of the support rod in contact with electrodes on the front and back surfaces of the transducer for transmitting electrical signals to and from the transducer. A syringe portion is detachably detached from the needle for receiving the back flow of blood when the needle is inserted into a blood vessel.

Abstract: An automatic urinary output monitor including a means for noninvasively determining the specific gravity of urine in a urine collection system including an oscillator with a feedback loop including ultrasonic transducers at opposite sides of a sampling chamber for producing an output signal with a frequency determined by the period of time it takes for a transmitted ultrasonic pulse to travel through the urine sample and to be received and means responsive to the frequency of the output signal for providing an indication of specific gravity of the urine sample.