Patents by Inventor Banhalli R. Ratna

Banhalli R. Ratna 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).

  • Nanoparticle phosphors manufactured using the bicontinuous cubic phase process
    Patent number: 6379583
    Abstract: Nanocrystalline phosphors are formed within a bicontinuous cubic phase.
    Type: Grant
    Filed: December 21, 1999
    Date of Patent: April 30, 2002
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Henry F. Gray, Jianping Yang, David S. Y. Hsu, Banhalli R. Ratna, Syed B. Qadri
  • Cell circuit for active matrix liquid crystal displays using high polarization, analog response liquid crystals
    Patent number: 6107980
    Abstract: An active matrix circuit for compact, high resolution reflective liquid ctal displays includes a low quiescent current, low output impedance MOS transistor amplifier produced in a CMOS process. A voltage controlled input switch effects the voltage refresh of the active matrix cell by passing a data voltage to the input of the transistor amplifier when a control voltage pulse is present on the input switch control line. All active matrix cells in a given row use the same input switch control line, and all active matrix cells in a given column access the same data input line. Refresh of the active matrix cell voltage terminates when the input switch is opened, storing the data voltage on the input node capacitance of the amplifier. The active matrix circuit is particularly addressed to liquid crystal devices having fast, analog response liquid crystals with large molecular polarizations such as in the Electroclinic Liquid Crystals (ELC).
    Type: Grant
    Filed: February 27, 1998
    Date of Patent: August 22, 2000
    Assignees: Geo-Centers, Inc., The United States of America as represented by the Secretary of the Navy
    Inventors: Anno Hermanns, Geoffrey L. Barrows, Banhalli R. Ratna
  • Nanoparticle phosphors manufactured using the bicontinuous cubic phase process
    Patent number: 6090200
    Abstract: Nanocrystalline phosphors are formed within a bicontinuous cubic phase. The phosphors are doped with an optimum concentration, of manganese, for example, corresponding to about one or less dopant ions per phosphor particle.
    Type: Grant
    Filed: November 18, 1997
    Date of Patent: July 18, 2000
    Inventors: Henry F. Gray, Jianping Yang, David S. Y. Hsu, Banhalli R. Ratna, Syed B. Qadri
  • Phosphors having a semiconductor host surrounded by a shell
    Patent number: 5985173
    Abstract: Phosphors having a doped core are surrounded by a shell material. Additionally, these nanocrystalline phosphors, or larger phosphors formed by conventional or other processes may be surrounded by a shell that prevents or significantly reduces non-radiative recombination at the surface of the original phosphor.
    Type: Grant
    Filed: November 18, 1997
    Date of Patent: November 16, 1999
    Inventors: Henry F. Gray, Jianping Yang, David S. Y. Hsu, Banhalli R. Ratna