Patents by Inventor Lars Fridh

Lars Fridh has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Perforated sound absorbing panel
    Patent number: 4830140
    Abstract: A perforated panel having a thickness of at least about 6 mm, for use as a sound absorbing element, especially at lacunarias. Each perforation is covered by a thin fiber cloth which is bonded to the edges of the perforation, rendering said panel element a specific acoustic flow resistance of between 1200 and 4000 Nsm.sup.-3.
    Type: Grant
    Filed: March 1, 1988
    Date of Patent: May 16, 1989
    Assignee: Gyproc AB
    Inventors: Lars Fridh, Stig Ingemansson