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:
Mar. 25, 1997
Filed:
May. 15, 1995
Crane & Co., Inc., Dalton, MA (US);
Abstract
A security thread for use in a paper-based value document, such as currency or banknote paper, includes a plastic substrate coated with one or more regions of 'soft' magnetic material. A device for verifying both the authenticity and the denomination of the document includes a coil that is driven by an alternating current to thereby provide a uniform magnetic field within a predetermined spatial region. As the document passes in proximity to the drive coil, the applied magnetic field saturates the regions of magnetic material on the security thread. The magnetic regions provide a response magnetic field that, because of the saturation of the magnetic regions, is a non-linear response containing a multiple of frequency components, including a component at the fundamental or drive frequency and various harmonic frequency components. A receive coil senses the response magnetic field. A signal processor connected to the receive coil utilizes the response signals at the fundamental frequency and the low-order harmonic frequencies to determine both the type of magnetic material on the security thread and the denomination of the document from the spatial distribution of the magnetic regions on the security thread.