Patents by Inventor Reinhold Wimberger-Friedl

Reinhold Wimberger-Friedl 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).

  • Polycarbonate copolymer of spirobisindan and bisphenol-A, method of preparing such a copolymer and optical components of such a copolymer
    Patent number: 5424389
    Abstract: A polycarbonate copolymer of a spirobisindan (6,6'-dihydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindan) and bisphenol-A in which the mole fraction of the spirobisindan .alpha. ranges between 0.844 and 0.887 is provided. Such a copolymer has a stress-optical coefficient C.sub.m in the melt which is equal to zero or substantially equal to zero, so that the sensitivity of the polymer to orientation birefringence is very small. Such a copolymer can be rendered optically isotropic and is very suitable for use in optical components in which birefringence is undesirable. Examples of such optical components are lenses and substrates for optical information media.
    Type: Grant
    Filed: April 12, 1994
    Date of Patent: June 13, 1995
    Assignee: U.S. Philips Corporation
    Inventors: Reinhold Wimberger Friedl, Harmannus F. M. Schoo, Johan G. De Bruin