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:
Apr. 02, 1985
Filed:
Sep. 30, 1983
Sadao Nomoto, Kamakura, JP;
Kazuyoshi Iida, Yokohama, JP;
Bridgestone Tire Company Limited, Tokyo, JP;
Abstract
Method and apparatus for forming a photographic record representing acoustic characteristics of a sound field such as the distribution of sound pressure and the distribution of equiphase surface wave are disclosed. A microphone and a light emitting diode are reciprocally moved to scan a plane in the sound field and an envelope signal of an output signal from the microphone is derived. The envelope signal is then sampled at a given sampling frequency to produce a sample signal. A carrier having a given frequency is amplitude-modulated with the sample signal to derive a modulated signal. Then, a switching circuit is controlled by the modulated signal in such a manner that when the envelope signal exceeds a predetermined value, the switching circuit is made on and off repeatedly and thus the light emitting diode is turned on and off at a rate of the carrier frequency to form a locas of the light spot. An image of the locus of the light spot is recorded optically on a photographic film.