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:
Aug. 22, 1989
Filed:
Mar. 18, 1987
Jacob K Higgs, Salisbury, NH (US);
Barbara L Gibson, Dorchester, MA (US);
Sprague Electric Company, North Adams, MA (US);
Abstract
A proximity detector includes a magnet having steel or iron pole piece plates mounted at front and rear pole ends of the magnet, and a silicon integrated circuit mounted to the outer surface of the front pole piece centered about at the magnet pole axis. The integrated circuit includes two essentially identical Hall elements having outputs connected series opposing, i.e. differentially rather than aiding, so that distortion of the magnet field ambient to the integrated circuit caused by a ferromagnetic article passing by results in a gradient field between the Hall elements producing a differential output signal. The dual Hall element integrated circuit leads to a low differential composite offset voltage while the front pole piece renders the magnetic flux density much more uniform further reducing this dual-Hall-element composite offset voltage.