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:
Sep. 14, 1999
Filed:
Oct. 24, 1996
Isak Kayserman, Needham, MA (US);
Simon Livson, Arlington, MA (US);
Allen-Bradley Company, LLC, Milwaukee, WI (US);
Abstract
An inductive proximity sensor and a method of proximity sensing are described that permit targets of interest to be detected despite the presence of external magnetic fields due to AC or DC sources, such as resistive welding machines. The sensor has a pair of matched coils positioned adjacent to one another along a common central axis. The coils are coupled in series with oscillator and detecting circuitry, that also serves to drive a switching device. The coils are wound for current flow in opposite directions and produce oscillating electro-magnetic fields for detecting the targets in response to signals from the oscillator and detecting circuitry. Currents in the coils induced by strong external magnetic fields produces an additional components of the coil field which essentially cancel one another. The sensing field of the coil assembly may be shaped and directed by cooperation of the fields of the two coils and by appropriate shielding around one or both coils.