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:
Jun. 03, 1997
Filed:
Aug. 15, 1994
Eiji Makabe, Kawasaki, JP;
Tsutomu Hoshino, Kawasaki, JP;
Atsushi Yamaguchi, Kawasaki, JP;
Tadashi Ohashi, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An active noise reduction device for reducing the noise produced by cooling fans in a computer. The active noise reduction device comprises a duct mounted on the casing of the computer and having at least one air passage. One end of the passage communicates with the interior of the casing near the cooling fans and the other end is open to the atmosphere. A first microphone is arranged in the duct near the first end opening for detecting noise, and a second microphone is arranged in the duct near the second end opening. A speaker is arranged in the duct near the second opening, and a controller controls the speaker in response to outputs of the first and second microphones for reducing the noise produced in the casing. The speaker makes a sound having a reverse phase to that of the noise produced in the computer and the speaker sound is superimposed on the noise.