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Noise cancellor

  • US 5,029,218 A
  • Filed: 09/29/1989
  • Issued: 07/02/1991
  • Est. Priority Date: 09/30/1988
  • Status: Expired due to Fees
First Claim
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1. A noise cancellor for canceling noise which is generated from a driving device and propagates to a predetermined object point, comprising:

  • a first sensor for detecting the noise generated from the driving device and converting the noise to electric signals;

    signal processing means for multiplying said electric signals by a predetermined factor series to form control signals;

    sound producing means for producing, in response to said control signals, sound which interferes with the noise so as to cancel the noise at the object point; and

    a second sensor for detecting sound at the object point, converting them to electric signals, and inputting them to the signal processing means;

    said signal processing means including adaptive active control means for changing said factor series in response to the electric signals detected by said second sensor, and selecting means for selecting a first control mode wherein said adaptive active control means is used or a second control wherein said factor series is fixed, in accordance with a predetermined condition, until the electric signals from the second sensor have a value which falls within a predetermined range.

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