Patents by Inventor Keith Eugene Coffman

Keith Eugene Coffman 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).

  • Method and apparatus for detecting a dry/wet state of a dual exposed thermistor bead liquid level sensor
    Patent number: 6662650
    Abstract: A method of detecting a dry/wet state of a dual thermistor bead sensor over a wide operating temperature range comprises the steps of: conducting first and second predetermined currents through one and another of the thermistor beads of the sensor, respectively, the second predetermined current being substantially less than the first predetermined current; measuring a first voltage across the one thermistor bead in response to the first predetermined current and generating a first signal representative thereof; measuring a second voltage across the other thermistor bead in response to the second predetermined current and generating a second signal representative thereof; modifying the second signal by an offset and gain to generate a third signal; and detecting the dry/wet state of the sensor over the wide operating temperature range based on the first and third signals.
    Type: Grant
    Filed: December 9, 2002
    Date of Patent: December 16, 2003
    Assignee: Simmonds Precision Products, Inc.
    Inventors: Scott Robert Durkee, Keith Eugene Coffman