The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 31, 1999
Filed:
Jun. 10, 1997
John S Sargent, Escondido, CA (US);
Frank T Sargent, Fort Myers, FL (US);
Other;
Abstract
A capacitive sensor includes a tubular outer conductor, a tubular inner conductor coaxial with the outer conductor, and an electrically insulated chamber between the inner and outer conductors. The material sample to be measured is introduced into the chamber. The sensor is shielded against electric fields to maximize measurement accuracy. The shielding completely encloses the chamber during operation and may include a removable cap, a valve, or a screen made of a conductive material. A measurement circuit connected to the sensor includes a reference oscillator that oscillates at a constant frequency and a test oscillator that oscillates at a frequency determined by the sensor capacitance. A circuit displays a value representing the sensor capacitance in response to the frequency difference between the test oscillator frequency and the reference oscillator frequency.