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Expired Canadian patentCanada

Device for increasing the compliance of a speaker enclosure

CA 1100884 A · Owner: Cerwin-Vega, Inc. · Inventors: Czerwinski, Eugene J.

CIPO record

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

The present invention is a device for use in combination with a loudspeaker system, that includes a speaker enclosure, in order to effectively enlarge the volume of the speaker enclosure. The loudspeaker system also includes a vibratable cone. The device for effectively enlarging the volume of the speaker enclosure includes a gas having a gamma less than 1.4 and the product of its density and the square of the speed of sound therein less than the same product for air and a bag which is formed from a soft, pliable material for enclosing the gas within the speaker enclosure and which is adapted to seal the gas therein. The device also includes an acoustically transparent and porous cocoon …

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Granted May 12, 1981. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended May 12, 1998.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledOctober 17, 1978
GrantedMay 12, 1981
Term endedMay 12, 1998
Patent numberCA 1100884 A
Classification (IPC)H04R1/28

Timeline

Timeline From CIPO dates

1979198119831985198719891991199319951997Application filedOct 17, 1978Patent grantedMay 12, 1981Term endedMay 12, 1998

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.