The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 18, 2000
Filed:
Jul. 16, 1997
Hans-Joachim Raida, Cologne, DE;
Oskar Bschorr, Munich, DE;
American Technology Corporation, Poway, CA (US);
Abstract
An ultrasonic beam (19) is used as a virtual array for an acoustic directional transmitter (11,21,31,41,51, and 61). The acoustic useful signal is modulated upon the ultrasonic beam as carrier via amplitude modulation, for example. The absorption of the ultrasonic power produces thermal expansion of the air and thus acoustic monopole radiation. At the same time, radiation pressure is released, resulting in dipole radiation. The superimposition of monopole and dipole produces a marked directivity characteristic. Since the ultrasonic sound possesses the same propagation velocity as the useful sound, the monopole and dipole radiation takes place within the virtual array correctly in terms of transit time, resulting in radiation that is directed extremely in the propagation direction. The effective array length can be adjusted over a wide range using the absorption coefficient that is a function of the carrier-frequency and, in extreme cases, a very punctual acoustic radiation can be realized at a wide distance. These types of directional transmitters are suitable as anti-sound generators and for directional signal and sound transmission. The ultrasonic carriers can be realized via piezoelectric (12) or pneumatic ultrasonic transmitters (22,32,42,52, and 62).