JP2925540B

PROBLEM TO BE SOLVED: To obtain a mechanism in which noise of super low sound generated by plural mechanisms having vibration sources such as a motor and beat sound caused by the sources are dissolved and attenuation directional control for attenuating sound pressure of a specified direction can be...

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Bibliographic Details
Main Authors YAMAMOTO SUSUMU, KIKUCHI TETSUKI, MAEDA TAKAYUKI, UMAE YOSHIO, NAKAYAMA KANEMITSU
Format Patent
LanguageEnglish
Published 28.07.1999
Edition6
Subjects
ACOUSTICS
ACOUSTICS NOT OTHERWISE PROVIDED FOR
METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING,NOISE OR OTHER ACOUSTIC WAVES IN GENERAL
MUSICAL INSTRUMENTS
PHYSICS
SOUND-PRODUCING DEVICES
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Summary:PROBLEM TO BE SOLVED: To obtain a mechanism in which noise of super low sound generated by plural mechanisms having vibration sources such as a motor and beat sound caused by the sources are dissolved and attenuation directional control for attenuating sound pressure of a specified direction can be performed. SOLUTION: A programmable controller PLC 41 measures a vibration frequency of each mechanism based on output signals of displacement sensors 13, 23 provided in mechanisms 11, 21 respectively, and sends a rotation speed indication signal of a motor 22 to an inverter 26 so that vibration frequencies of both mechanisms are equalized. Beat sound is dissolved by this feedback control. Also, the PLC 41 changes properly a rotation speed indication signal sent to the inverter 26 so that the mechanisms 11, 12 are vibrated with a phase difference angle to lower a sound pressure level of a place (direction) where a noise problem is dissolved.
Bibliography:Application Number: JP19980212130