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:
Nov. 01, 1988
Filed:
Jul. 09, 1986
Wesley J Bachman, Auburn, IL (US);
Dickey-john Corporation, Auburn, IL (US);
Abstract
A sensor apparatus for detecting a flow of material along a given path of travel by detecting a change in the dielectric properties of a portion of the path of travel as the material passes therethrough comprises one or more conductive, plate-like electrodes disposed adjacent the path of travel and generally defining a capacitor having the adjacent portion of the path of travel as a dielectric portion, such that the passage of material to be detected changes the dielectric constant, thereby changing the capacitance. A sensor circuit comprises a tuned circuit having the sensor electrode or electrodes being coupled in circuit therewith. The sensing circuit further comprises an oscillator circuit driving the tuned circuit at a predetermined frequency selected near the resonant frequency of the tuned circuit in the absence of material to be detected. The sensing circuit further includes an AM demodulator circuit coupled to the tuned circuit for developing a sensor circuit signal at a substantially constant level in the absence of material to be detected and a measurable change in signal level when the material to be detected is present.