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:
Nov. 23, 1976
Filed:
Nov. 20, 1975
Leo C Miller, Wheaton, MD (US);
Other;
Abstract
The invention relates to a device which holds a coin within a moving magnetic field and provides a means for determining the metallic content of the coin based upon the resultant eddy current losses generated in the coin. The moving magnetic field is provided by one or more pairs of magnets mounted in a wheel such that the coin can be inserted into a gap in the wheel through which the magnetic field lines pass. The wheel is accelerated rotationally to a speed higher than some first reference speed, then a precise measurement is made of the time required for the wheel to decelerate from the first reference speed to a second (lower) reference speed. The deceleration is dependent upon the size and shape of the coin, and upon its electrical resistance, which, in turn, is dependent upon the coin's metallic constituents and their proportions, so that the deceleration time for a particular coin can be compared to the deceleration time of like coins, to provide a good measure of the metallurgical authenticity of the coin. The time measurement is facilitated by a stroboscopic pattern affixed to one side of the wheel, so that relative speeds can be accurately identified by observing the wheel while it is illuminated with fluorescent lights. Acceleration of the wheel is provided by a pull-string wrapped around the wheel axle, or by a hand-held motor with a rubber drive wheel. The time required to decelerate between the two reference speeds is measured.