Patents Assigned to N.P.L. Ltd.
  • Loudspeaker-and-pre-stressed cabinet
    Patent number: 6628797
    Abstract: Disclosed is an improved loudspeaker comprising a pre-stressed cabinet and a loudspeaker unit fixed to the inside of the cabinet. The cabinet comprises a hollow conical assembly including two conical bodies of high-rigidity metal, one press-fitted into the other by applying an increased compressive force. The hollow conical assembly has front and rear plates closing its front and rear openings. These front and rear plates are pulled toward each other by tightening screw rods.
    Type: Grant
    Filed: April 17, 2001
    Date of Patent: September 30, 2003
    Assignee: N.P.L. Ltd.
    Inventor: Teppei Yamada
  • Speaker structure
    Patent number: 5194701
    Abstract: Disclosed is an improved speaker structure having a rigid unit-support member and a sound-intercepting wall. In order to improve the quality of reproduced sound, the sound-intercepting wall is composed of a layer of sound-absorbent material which is applied at least to outer surface of said unit-support member and a soundproof sheet of an acoustic energy-absorbent material which covers up tightly the layer of sound-absorbent material.
    Type: Grant
    Filed: September 11, 1991
    Date of Patent: March 16, 1993
    Assignee: N.P.L. Ltd.
    Inventor: Teppi Yamada-Scriba