Patents by Inventor Gopalan Vijayakumar

Gopalan Vijayakumar 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).

  • Preparation of conductive toners using fluidized bed processing equipment
    Patent number: 5350659
    Abstract: A method for making conductive toner particles includes (A) heat treating in fluidized bed processing equipment a mixture of non-conductive toner particles containing a thermoplastic resin and a colorant, and an effective amount of conductive powder blended with and coated on surfaces of the non-conductive toner particles, wherein the heat treatment is carried out at a temperature at or above the glass transition temperature of the resin for a period of time at least sufficient to fuse the conductive powder onto the surfaces of the non-conductive toner particles, and then (B) cooling the heated conductive toner particles to a temperature below the glass transition temperature of the resin. The final toner particles have a conductivity of at least about 10.sup.-8 ohm.sup.-1 -cm.sup.-1 and preferably from about 10.sup.-4 to about 10.sup.-8 ohm.sup.-1 -cm.sup.-1.
    Type: Grant
    Filed: March 31, 1993
    Date of Patent: September 27, 1994
    Assignee: Xerox Corporation
    Inventors: Frank P. Lee, Sheau V. Kao, Gerald R. Allison, Hadi K. Mahabadi, Geroge Liebermann, Gopalan Vijayakumar, Robert A. Downing