Patents by Inventor Andrew R. Ralston

Andrew R. Ralston 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).

  • Capacitance humidity sensor
    Patent number: 5408381
    Abstract: A capacitance humidity sensor according to the invention has a film core which is in contact with a pair of conductive layers bonded to opposite faces of the core. The core is made of a polyimide having a dielectric constant which varies substantially linearly with humidity and which includes at least one ether linkage in the dianhydride portion thereof. The polyimide may also include at least one ether linkage in the diamine portion thereof and/or at least one fluorine atom in the diamine, dianhydride or both the diamine and dianhydride portions thereof.
    Type: Grant
    Filed: April 28, 1994
    Date of Patent: April 18, 1995
    Assignee: Johnson Service Company
    Inventors: Paul E. Thoma, Carl F. Klein, Alexander M. Blok, Andrew R. Ralston