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:
Mar. 31, 1998
Filed:
Dec. 08, 1994
Earl B Hoekman, Roseville, MN (US);
Martin C Henderson, Reseda, CA (US);
Minnesota Mining and Manufacturing Company, St. Paul, MN (US);
Abstract
The period T.sub.nv of an oscillator signal is measured. A number N.sub.meas of cycles of the oscillator signal is determined based upon the measured oscillator period T.sub.nv and upon a desired minimum change in inductance .DELTA.L (sensitivity) which will result in an object being detected. The N.sub.meas cycles of the oscillator signal represent a measurement period. The length of the measurement period, defined by N.sub.meas oscillator cycles, is periodically determined. The length of the measurement period is compared to a reference value. An output, based upon the results of the comparison, is provided. Thereafter, the desired minimum change in inductance .DELTA.L (sensitivity) may be automatically adjusted by determining an average magnitude change in inductance .DELTA.L.sub.ave caused by a plurality of vehicles. The number N.sub.meas of oscillator cycles, which define the measurement period, is recalculated based upon the average magnitude change in inductance.