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Gradiometer Document Detector for Copy Security

IP.com Disclosure Number: IPCOM000080280D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Boggs, BR: AUTHOR [+2]

Abstract

Fig. 1 shows a schematic arrangement for a security control of an office copier, while Fig. 2 shows a diagram of a piece oi paper with a metal or flag or back coating on the paper to indicate that it is a secure document and should not be copied.

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Gradiometer Document Detector for Copy Security

Fig. 1 shows a schematic arrangement for a security control of an office copier, while Fig. 2 shows a diagram of a piece oi paper with a metal or flag or back coating on the paper to indicate that it is a secure document and should not be copied.

Magnetic field generator 10 provides an electrical current through conductors 12 to coils 14, to create a background flux level or flux field in the vicinity of document plane 16. Sensing coils or magnetic field detector coils 18 are placed in the magnetic field created by the coils 14 and in close proximity to document plane 16. Detector coils 18 are connected to the magnetic field change detector circuit 20, which will detect any chnnge in the flux field generated by coils 14. If such a change occurs as a result of a foreign metallic object being within the flux field, the output signal from the field change detector through conductor 22 will act to actuate the copier disable control 24.

Copier disable control 24 may be of the type which requires resetting by the Customer Engineer or may be automatically reset by the removal of a document which has been flagged. The effecting of a magnetic field change is accomplished by using documents having a writing surface of paper 26, as illustrated in Fig. 2, and a backing layer of a metallic material 28. The metallic material should be a permeable material which will cause a substantial shift in the flux field in the vicinity of d...