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:
Dec. 09, 2003
Filed:
Apr. 23, 2002
Sten Linder, Vasteras, SE;
ABB AB, Vasteras, SE;
Abstract
A method for non-contact measurement of dimensions such as thickness or diameter and electrical characteristics of an electrically conductive object ( ) based on electromagnetic induction and a time-varying magnetic field. A substantially constant current is supplied to at least one transmitter coil ( ) such that an electromagnetic field penetrates the object ( ). Current to the transmitter coil ( ) is cut off and a voltage induced in at least one receiving coil ( ) by at least one decaying magnetic field. The voltage in receiving coil ( ) is measured from a first time following decay of a magnetic field in the air (T ) until a time when the field has decayed to zero (T , T , T ) and the signal is integrated. A value for a physical dimension of the object ( ) is calculated from this integral. The method is accurate, undisturbed by surface contamination or object movement, and applicable to different geometric forms including plate, bar or tube.