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:
Dec. 12, 2006
Filed:
Oct. 20, 2004
Anne Kelley, Corvallis, OR (US);
Anne Kelley, Corvallis, OR (US);
White's Electronics, Inc., Sweet Home, OR (US);
Abstract
A metal detector for detecting objects that are composed of non-ferrous metals. The metal detector provides for a reduced rate of false positive responses to objects composed of ferrous metals. A preferred metal detector according to the invention includes a transmitter for transmitting a time-varying electromagnetic signal and a receiver for receiving a responsive time-varying electromagnetic signal produced by the metal object. The metal detector also includes an analyzer for determining the resistive and reactive components of the responsive signal as respective first and second functions of the spatial position of the detector. A module for determining and comparing rates of change of the first and second functions at one or more spatial positions is included. Preferably, when the rates of change are the first derivatives or slopes of the functions, and when these are of the same sign, a result indicating that the metal object is non-ferrous is provided by the module. A preferred method for identifying with an improved degree of reliability a non-ferrous metal object versus a ferrous object. The resistive and the reactive components of the responsive electromagnetic signal are determined as respective first and second functions of the spatial position of the detector, and the rates of change of the first and second functions at one or more spatial positions are compared. Preferably, if the rates of changes are the first derivatives or slopes of the functions, and these are of the same sign, a result that the object is non-ferrous is provided.