Patents by Inventor David E. Birt

David E. Birt 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).

  • Patent number: 4364816
    Abstract: An apparatus, for use in an electroplating arrangement, for establishing electrical contact with a metal or metalized cathode plate used in production of a disc record matrix. The apparatus includes an electrically conductive contact member and a clamping means for holding the contact member against a cathode plate supported by the apparatus. The contact member and clamping means are shaped so that electrical contact is established at the periphery only of the cathode plate.
    Type: Grant
    Filed: December 5, 1980
    Date of Patent: December 21, 1982
    Assignee: EMI Limited
    Inventor: David E. Birt
  • Patent number: 4288481
    Abstract: A two stage moulding procedure for the production of foil video discs. In a first pressing operation a satin finish consisting of a surface irregularity is applied to a surface of the foil, and then, in a second pressing operation, the foil is pressed between stamper plates to impart thereto, at one or both surfaces an impression of the information or data to be recorded. The satin finish may be formed by pressing the foil between stamper plates bearing the satin finish at their inwardly facing surfaces or alternatively between a pair of rollers bearing the satin finish at their surfaces.
    Type: Grant
    Filed: July 11, 1980
    Date of Patent: September 8, 1981
    Assignee: EMI Limited
    Inventors: David E. Birt, Peter J. Clarke
  • Patent number: 4277071
    Abstract: A record having an information track cut into the surface and a visible pattern formed on surface "lands" bordering the track. The pattern is shallower than the track depth, typically 0.7 micron for a 25 micron sound microgroove record track. A method of providing the marking by applying solvent to a lacquer before cutting a master is described.
    Type: Grant
    Filed: February 17, 1978
    Date of Patent: July 7, 1981
    Assignee: E M I Limited
    Inventors: David E. Birt, Lyn Holt
  • Patent number: 4231730
    Abstract: A means for moulding thermoplastics video discs having one or two shaped resilient compensators to maintain the stamper plates in parallelism with the plastics foil during moulding. The compensators may be of a rubber and may contain a thermally conductive material.
    Type: Grant
    Filed: November 6, 1979
    Date of Patent: November 4, 1980
    Assignee: E M I Limited
    Inventor: David E. Birt