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:
May. 15, 1984
Filed:
Aug. 02, 1983
Ralph J Koerner, Pomona, CA (US);
Minnesota Mining and Manufacturing Company, Saint Paul, MN (US);
Abstract
A convertor is used having an impedance responsive to the magnetic field intensity of the earth. The convertor may be coupled to a detector for monitoring the impedance of the convertor and generating a call signal responsive to the change in impedance. Generally, the impedance is primarily inductance and the detector is an oscillator using the convertor in a resonant circuit with a frequency monitor coupled to the detector. The convertor is an open magnetic structure having a non-linear BH curve biased by the earth's magnetic field. The open magnetic structure is a core of a highly permeable material which approaches saturation under the influence of the earth's magnetic field, with the axis of the core at least partially aligned with the magnetic flux lines of the earth's magnetic field, and a coil wound around the axis of the core.