EP0557071A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Active noise control apparatus for three-dimensional space
Assignee: Hitachi Ltd
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Filing: 1993-02-17
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Granted: —
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Expires: 2013-02-17
Abstract
Abstract An active noise control system for a three-dimensional space, including noise detecting means, sound generating means, noise control effect detecting means and a control device consisting of a phase of a wave signal fed from the noise detecting means wherein a plurality of noise control effect detecting means and sound generating means are disposed at a distance shorter than a wavelength of the noise to be controlled, and input signals of the respective sound generating means and output signals of the respective noise control effect detecting means are fed through filters, separately, to control the sound for active noise control. In case of an air conditioner, the noise control effect detecting means are disposed at positions where an air stream flowing through the air conditioner is not obstructed thereby.
Inventors
- 👤 Shinya Okabem
- 👤 Shinichi Shimode
- 👤 Ryouji Sato
- 👤 Masamichi Hanada
- 👤 Takao Senshu
- 👤 Hirokiyo Terada
- 👤 Minetoshi Izushi
- 👤 Hiroshi Takenaka
- 👤 Masahiro Ito
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 04:32
CPC Classifications
F; F24; F24F; F24F13/00; F24F13/24; G; G10; G10K; G10K11/00; G10K11/16; G10K11/175; G10K11/178; G10K11/1785; G10K11/17853; G10K11/17854; G10K11/17857; G10K11/1787; G10K11/17879; G10K11/17881; G10K11/17885; F24F2013/247; G10K2210/00; G10K2210/10; G10K2210/104; G10K2210/121; G10K2210/30; G10K2210/321; G10K2210/3216
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
164 words
An active noise control apparatus for a three-dimensional space including a noise detecting means for detecting a noise radiated from a noise source, a control device for controlling an active noise control, a plurality of sound generating means and a plurality of noise control effect detecting means, said sound generating means being disposed at positions surrounding said noise source, with distances between said noise source and each source generating means and between the respective source generating means being shorter than 1/2 of a wavelength of a maximum frequency of a noise to be controlled, said control device for active noise control being arranged to cause said sound generating means to radiate a sound wave having opposite phase to and same sound pressure, same wavelength and same directivity as those of a noise having a wide frequency range radiated from said noise source into a three-dimensional space, on the basis of output signals of said noise detecting means and said noise control effect detecting means.
Claim 2
Dependent Claim
63 words
An active noise control apparatus according to claim 1, wherein at least one of said plurality of sound generating means has a sound transmitting tube for transmitting a sound from said sound generating means and said sound transmitting tube is disposed at a position where a sound radiating position of the sound transmitting tube is located to satisfy the requirement defined as above.
Claim 3
Dependent Claim
90 words
An active noise control apparatus according to claim 1 or 2 wherein fixed filters are interposed between said plurality of sound generating means and said control device and between said plurality of noise control effect detecting means and said control device, respectively, said fixed filter having a characteristic determined on the basis of actually measured values of transfer functions between these sound generating means and a representative spot in the three-dimensional space and transfer functions between the noise control effect detecting means and the representative spot in the three-dimensional space.
Claim 4
Dependent Claim
54 words
An active noise control apparatus according to claim 1, 2 or 3, wherein fixed filters are interposed between said noise detecting means and said control device, said fixed filter having a characteristic which is determined on the basis of transfer functions between said noise detecting means and the representative spot in the three-dimensional space.
Claim 5
Dependent Claim
58 words
An active noise control apparatus according to claim 3 or 4, wherein an adaptive filter or filters having characteristics corresponding to the above-mentioned transfer functions and making variations on the basis of output signals of said noise detecting means and the noise control effect detecting means are used, instead of a part or whole of the fixed filters.
Claim 6
Dependent Claim
46 words
An active noise control apparatus according to any one of claim 1-5, wherein said plurality of noise control effect detecting means are located at positions where a sound pressure produced by interference of sounds coming from said noise source and said sound generating means becomes minimum.
Claim 7
Dependent Claim
51 words
An active noise control apparatus according to any one of claim 1-6, wherein said noise source exists in an air conditioner and said noise detecting means, and said control device for active noise control, said sound generating means and said noise control effect detecting means are disposed in said air conditioner.
Claim 8
Dependent Claim
33 words
An active noise control apparatus according to claim 7, wherein said plurality of sound generating means are disposed at positions where an air stream flowing through the air conditions is not obstructed thereby.
Claim 9
Dependent Claim
188 words
An active noise control apparatus including a noise detecting means, a sound generating means for active noise control, a noise control effect detecting means disposed at a local noise control area to detect a sound within said noise control area and a control device for active noise control, said control device for active noise control being arranged to control said sound generating means to effect an active noise control to cause a sound reached said noise control area from said sound generating means detected by said noise control effect detecting means to become minimum under the action of a sound having opposite phase to and same sound pressure and same wavelength as those of the noise to be controlled, on the basis of detecting output signals fed from said noise detecting means and said noise control effect detecting means; Wherein said noise control effect detecting means can be located at any desired positions, and said control device for active noise control and said noise control effect detecting means are connected together by signal transmitting means including flexible and movable parallel cords, coaxial cables, optical fibers or radio waves.
Claim 10
Dependent Claim
38 words
An active noise control apparatus according to claim 9, wherein a plurality of sound generating means are provided, and a plurality of noise control effect detecting means are located at local noise control areas in the three-dimensional space.
Claim 11
Dependent Claim
36 words
An active noise control apparatus according to claim 9, wherein a plurality of sound generating means are provided and a plurality of noise control effect detecting means are disposed separately in the local noise control areas.
Claim 12
Dependent Claim
67 words
An active noise control apparatus according to claim 10, wherein a plurality of noise control effect detecting means are disposed at distances shorter than one half to one thirds of a wavelength of a noise to be controlled and the plurality of local noise control areas are arranged to be assembled together to form a large local noise control area surrounding the noise control effect detecting means.
Claim 13
Dependent Claim
46 words
An active noise control apparatus according to claim 9, 10, 11 or 12, wherein said sound generating means and said control device for active noise control are connected together by signal transmitting means including flexible and movable parallel cords, coaxial cables, optical fibers or radio waves.
Claim 14
Dependent Claim
38 words
An active noise control apparatus according to any one of claims 9-13, wherein sound transmitting tubes are provided to conduct sounds for active noise control radiated by said sound generating means from any position into the three-dimensional space.
Claim 15
Dependent Claim
32 words
An active noise control apparatus according to any one of claims 9-14, wherein the noise source exists in an air conditioner and the noise detecting means are located in said air conditioner.
References Cited (Backward Citations)
No citation records indexed.
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