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:
Sep. 10, 2002
Filed:
May. 13, 1999
Yoshinobu Yasuno, Tokyo, JP;
Yasuhiro Riko, Yokohama, JP;
Other;
Abstract
A digital electro-acoustic transducer for improving the speech quality of sound under noisy circumstances is disclosed. A plurality of sound generating units A constituted by electrostatic electro-acoustic transducers (condenser earphones) and a sound receiving unit B constituted by an electrostatic acousto-electric transducer (condenser microphone) are disposed in a cavity of a soundproof housing. The units A are provided in a feedback loop and an output level of the unit B is adjusted by an preamplifier. An output of the preamplifier is sampled by a sample-and-hold circuit and an output thereof is delta-modulated by a delta modulation circuit. The number of pulses produced by the circuit is subjected to arithmetic operation in an arithmetic circuit to produce a drive signal for the units A. Vibration of a vibration film of the unit B is detected and arithmetical control is made to be always maintained to zero. On the other hand, an audio signal supplied from a signal terminal is superposed on a drive signal for the units A and is emitted into the cavity.