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:
Sep. 28, 1976
Filed:
Jan. 14, 1975
Paul E Bakeman, Jr, Elnora, NY (US);
Albert L Armstrong, Latham, NY (US);
American District Telegraph Company, Jersey City, NJ (US);
Abstract
In a pilferage detection system employing apparatus for generating a magnetic field of alternating polarity and predetermined fundamental frequency through which articles subject to pilferage must pass to leave a protected area and a magnetic marker associated with each article in the protected area, markers are provided which generate both odd and even harmonics of the fundamental frequency in response to the alternating magnetic field when the marker is active (i.e., a control element of the marker is magnetized) and which generate only odd harmonics of the fundamental frequency when the marker is inactive. The presence of an active marker in the alternating magnetic field is therefore detected by detecting a predetermined even harmonic of the fundamental frequency. Apparatus is also provided for demagnetizing the control element of the marker associated with an article authorized for removal from the protected area to permit that article to pass through the alternating magnetic field undetected.