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:
Jun. 29, 1999
Filed:
Apr. 28, 1997
P Karl Scheller, Rochester, NH (US);
Ravi Vig, Bow, NH (US);
Jay M Towne, Newbury, NH (US);
Hitoshi Yabusaki, Worcester, MA (US);
Allegro MicroSystems, Inc., Worcester, MA (US);
Abstract
A method for detection of passing magnetic articles which includes an initial step of sensing an ambient magnetic field and generating a voltage, Vsig, proportional to the magnetic field. A threshold voltage is generated as a percentage of the peak-to-peak voltage of Vsig. The method further includes the step of generating a proximity detector output voltage that becomes one binary level when Vsig rises to exceed the threshold voltage and another binary level when Vsig falls to below the threshold voltage. The threshold voltage is periodically updated to remain the percentage, within a predetermined tolerance, of the peak-to-peak voltage of Vsig in response to changes that may occur in the peak voltages of Vsig. In one embodiment, the threshold voltage is at a first level corresponding to a first percentage of the peak-to-peak voltage of Vsig when Vsig exceeds the threshold voltage and is at a second level corresponding to a second percentage of the peak-to-peak voltage of Vsig when Vsig is less than the threshold voltage.