Patents by Inventor Michael Stefanov

Michael Stefanov 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).

  • High contrast reflective light valve
    Patent number: 6836309
    Abstract: The invention involves a novel method and structure for utilizing homeotropic vertically aligned nematic liquid crystal cells in the production of high contrast microdisplays. Two circular polarizers are used in order to propagate circularly polarized, rather than planar polarized, light through a liquid crystal cell. The use of circularly polarized light eliminates the liquid crystal director alignment requirements for the transmittance of light necessary for planar polarized light. With no director alignment requirement, it is possible to use perfectly homeotropic vertically aligned nematic cells irrespective of domain size and shape because fringing field induced director tilt will not decrease the transmittance of the liquid crystal cell.
    Type: Grant
    Filed: November 30, 2000
    Date of Patent: December 28, 2004
    Assignee: HANA Microdisplay Technologies, Inc.
    Inventors: James Anderson, Michael Stefanov
  • High contrast reflective light valve
    Publication number: 20020063818
    Abstract: The invention involves a novel method and structure for utilizing homeotropic vertically aligned nematic liquid crystal cells in the production of high contrast microdisplays. Two circular polarizers are used in order to propagate circularly polarized, rather than planar polarized, light through a liquid crystal cell. The use of circularly polarized light eliminates the liquid crystal director alignment requirements for the transmittance of light necessary for planar polarized light. With no director alignment requirement, it is possible to use perfectly homeotropic vertically aligned nematic cells irrespective of domain size and shape because fringing field induced director tilt will not decrease the transmittance of the liquid crystal cell.
    Type: Application
    Filed: November 30, 2000
    Publication date: May 30, 2002
    Inventors: James Anderson, Michael Stefanov
  • Apparatus for and method of operation of smectic liquid crystal light valve having scattering centers
    Patent number: 5140448
    Abstract: A liquid crystal light valve, comprising a layer of liquid crystal for storing image information and a photoconductor aligned with the liquid crystal and positioned in closed proximity thereto for effecting an electric field applied across the liquid crystal. Apparatus is provided for simultaneously applying an electric field across the liquid crystal and photoconductor while impinging optical image information on the photoconductor, the photoconductor and applied field combining to produce a modified electric field across the liquid crystal which impresses the image information on the photoconductor into the liquid crystal.
    Type: Grant
    Filed: October 24, 1990
    Date of Patent: August 18, 1992
    Assignee: Greyhawk Systems, Inc.
    Inventors: Matthew Bone, David E. Slobodin, Duane A. Haven, Michael Stefanov, Frederic J. Kahn