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:
Oct. 03, 1995
Filed:
Jan. 05, 1995
Noriharu Sato, Tokyo, JP;
Hiroyuki Saito, Katsuta, JP;
Satoshi Hasegawa, Yamato, JP;
Osamu Igarashi, Isehara, JP;
Hitachi, Ltd., both of, JP;
Nissan Motor Co., Ltd., both of, JP;
Abstract
When noise is caused by the mechanical vibration propagated from the engine, the microprocessor calculates from the vibration frequency of the engine the secondary sound signal which is in antiphase with the noise and which is thus able to cancel out the noise, and supplies it to the loudspeaker which then emanates the secondary sound according to this signal. At this time,the divergence detection circuit monitors the incoming secondary sound signal, and when the secondary sound signal is remarkably increased, it decides that the noise is increased, and automatically stops the secondary sound output from the loudspeaker. Therefore, it can be prevented that the noise is reversely increased by the secondary sound.