Abstract: A method for controlling a plurality of ultrasonic transducers in a fingerprint sensing system that comprises a cover plate having a sensing surface configured to be touched by a finger, and a plurality of ultrasonic transducers located at the periphery of the cover plate and configured to transmit an acoustic signal propagating in the cover plate, receive an ultrasonic signal having interacted with an object in contact with the sensing surface, and to determine properties of the object based on the received ultrasonic signal. The method comprises: in response to a first input, controlling the plurality of transducers such that at least a portion of the sensing surface has a first feature detection resolution; and in response to a second input, controlling the plurality of transducers such that at least a portion of the sensing surface has a second feature detection resolution, different from the first feature detection resolution.

Abstract: A method for controlling a plurality of ultrasonic transducers in a fingerprint sensing system that comprises a cover plate having a sensing surface configured to be touched by a finger, and a plurality of ultrasonic transducers located at the periphery of the cover plate and configured to transmit an acoustic signal propagating in the cover plate, receive an ultrasonic signal having interacted with an object in contact with the sensing surface, and to determine properties of the object based on the received ultrasonic signal. The method comprises: in response to a first input, controlling the plurality of transducers such that at least a portion of the sensing surface has a first feature detection resolution; and in response to a second input, controlling the plurality of transducers such that at least a portion of the sensing surface has a second feature detection resolution, different from the first feature detection resolution.

Abstract: The invention relates to an impulse sound traducer for the ultrasonic range. Transducers in prior art require complicated and expensive technology in order to really generate good impulses. The invention aims at providing a sound transducer for the ultrasonic range, which transmits strong and short impulses, has high senstivity and ensures repeatability of parameters. This is achieved by a sound transducer for the ultrasonic range that is used both as a transmitter and as a receiver and is comprised of an elementary block made of piezoelectric material, wherein the height of the elementary blocks consisting of piezoelectric material is bigger than its width and the block on the output end of the impulse has a formed edge so that the elementary block has a T-shape in the longitudinal section, wherein one electrode is provided on the outlet surface while the other electrode extends above the edge on the block.

Abstract: A method and an apparatus for analyzing a structure, for example, a fingerprint or a hand print, in which the finger or hand is placed upon a plate which forms an ultrasonic wave waveguide and ultrasonic radiation, launched into the waveguide parallel to the surface against which the object is placed. The reflected and backscattered waves are analyzed utilizing horizontally polarized ultrasonic shear waves propagated in the body from at least one transducer at a side of the body. The pickup transducer can also be provided on the side of the body.

Abstract: A generator for spherical ultrasonic waves can replace a point source transducer and has a large-area transducer whose output ultrasonic waves are condensed in a funnel and fed to a monomodal waveguide, e.g. a tube at the output end of which phase-correct perfectly spherical waves are emitted.

Abstract: The number of transducers in the scanning of an ultrasonic field from an object is reduced by providing ultrasonic collectors at spaced apart locations in the medium and transmitting the ultrasonic waves which are collected to a transducer through waveguides or paths having different transit times. The waveguides can be individually of different lengths or can be of equal length and terminate at different distances along a common collecting waveguide.

Abstract: For determination of surface and special surface characteristics of an object, e.g. a fingerprint, the finger tip is placed on a convex surface of a support which is irradiated through a liquid or solid medium with spherical ultrasonic waves from a point source provided as a hole in a carrier for a ring of receiving transducers.

Abstract: A method of detecting fingerprints by sensing scanning with ultrasonic waves. For comparison, an acoustic hologram of the characteristics of the respective finger is disposed in an identification card. The hologram is compared in a recognition device with an ultrasonic interference pattern which is obtained by reflection of ultrasonic waves at an interface formed between the surface of the finger and a planar application or support surface.