Loading patent…
AssigneeHitachi, Ltd.
InventorsShinya Okabe, Shinichi Shimode, Ryouji Sato, Masamichi Hanada, Takao Senshu, Hirokiyo Terada, Minetoshi Izushi, Hiroshi Takenaka, Masahiro Ito
Estimating the term…
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.
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 sound generating means and between respective sound 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 an opposite phase to and a 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 a basis of output signals of said noise detecting means and said noise control effect detecting means.
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 reaching said noise control area from said sound generating means detected by said noise control effect detecting means to become minimum under an action of a sound having an opposite phase to and same sound pressure and same wavelength as those of noise to be controlled, on a basis of detecting output signals fed from said noise detecting means and said noise control effect detecting means;
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 reaching said noise control area from said sound generating means detected by said noise control effect detecting means to become minimum under an action of a sound having an opposite phase to and same sound pressure and same wavelength as those of noise to be controlled, on a basis of detecting output signals fed from said noise detecting means and said noise control effect detecting means;
Dependencies are inferred from the claim text.