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. 05, 1995
Filed:
Feb. 28, 1994
Joseph R Guerci, Astoria, NY (US);
Raymond Guerci International, Inc., Staten Island, NY (US);
Abstract
An active noise cancellation device and method for reducing fan blade noise over a broad spatial area. The device comprises a microphone, a band pass filter, and audio amplifier, and a speaker array. The microphone captures the sound produced by the fan and converts it into an electrical signal. This electrical signal is input to the band pass filter which has a center frequency equal to product of fan speed and the number of fan blades which comprise the fan. The band pass filter attenuates any signals other than the primary harmonic sound produced by the rotating fan blades. The filtered signal from the band pass filter is input to the audio amplifier. The audio amplifier conditions the signal for input to the speaker array. Accordingly, each speaker in the array receives and outputs an audio signal of equal amplitude and phase as that produced by the rotating fan blades. The speaker array is mounted on or close to the fan hub in a symmetric pattern commensurate with the fan blade geometry. In general, the number of speakers which comprise the array corresponds to the number of fan blades. The position of the speaker array is adjusted until a maximum destructive interference occurs between the sound produced by the rotating fan blades and the speaker array. With the addition of a phase shifter, the active noise cancellation device can be utilized to provide noise cancellation for variable speed fans.