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. 19, 1991
Filed:
Dec. 13, 1989
Thomas E Beling, Framingham, MA (US);
Wayne M Spani, San Diego, CA (US);
Winfield Corporation, San Diego, CA (US);
Abstract
A device for detecting the passage of a ferromagnetic object through a predetermined space has a substantially circular base which circumscribes the space. An inner detector coil and an outer detector coil are concentrically mounted in coplanarity on the base. Voltages are induced on the coils in response to the passage of a nearby magnetic field, such as the small permanent magnetic field associated with a ferromagnetic object. A signal processing circuit compares the induced voltages on the coils to indicate passage of a metal object through the circumscribed space when the inner coil voltage exceeds the outer coil voltage.