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Llllllillllllllllllllllllllllllllllllllllllllllllllllllll||Ll|||L|L|L|||Ll| llllllIllllllllllllllllllllllllllllllllllllllllllllllllll||ll|||l|l|l|||ll| USOO561691 1A Unlted States Patent [19] [11] Patent Number: 5,616,911 Jagielinski [45] Date of Patent: Apr. 1, 1997 [54] READ-ONLY MAGNETIC SECURITY 4,237,189 12/1980 Deifeyes . PATTERN 4,281,043 7/1981 Deffeyes . 4,855,584 8/1989 Tomiyama et a1. [75] Inventor: Tomasz M. Jagielinski, Carlsbad, Calif. 4,863,196 9/1989 01111151“ et a1~ - 4,982,076 1/1991 Fupta . - . 5,196,681 3/1993 Mantegazza . [73] Asslgnee' 1132mm K°dak Company’ Rwhester’ 5,418,458 5/1995 Jeifers ................................... .. 324/235 Primary Examiner-Harold Pitts [21] Appl. No.: 448,945 Attorney, Agent, or Firm—WilliaIn F. Noval [22] Filed: May 24, 1995 [57] 7 ABSTRACT [52] US.Int. Cl.6Cl. .............................................................................................. .. 235/493; u 235/449 Acode, Security patterns, device and andparticularly System formagnetic encoding bar documentscode patterns or [58] Field of Search .................................... .. 235/449, 493 other indicia exhibiting zero remanence. An in-?eld mag netoresistive (MR) sensing element read head is employed [56] References Cited to magnetize the bar code pattern bands and detect their m E width or spacing apart as they are advanced with respect to us‘ PATENT DOC NTS the head. After read out, the bar code pattern bands exhibit 3,566,356 2/1971 Holm et a1. practically no residual magnetic ?eld and are not readable by 3,790,754 2/1974 Black et a1. a magnetic viewer. The code patterns may be in any shape 4,124,735 11/1978 O’Horo ................................. .. 428/406 or format for adding security to documents of all types. 4,182,481 1/1980 Maussion . 4,203,544 5/1980 Guilgue . 4,225,780 9/1980 Jacoub et a1. 24 Claims, 3 Drawing Sheets 44 46 US. Patent Apr. 1, 1997 Sheet 1 of 3 5,616,911 FIG. 1 PRIOR ART US. Patent Apr. 1, 1997 Sheet 2 of 3 5,616,911 X 68 72 [6D “ US. Patent Apr. 1, 1997 Sheet 3 of 3 5,616,911 5,616,911 1 2 READ-ONLY MAGNETIC SECURITY In a further US. Pat. No. 4,182,481, a series of spaced PATTERN apart magnetoresistive (MR) sensor heads are employed in line with a permanent magnet for magnetizing the bar code hands before the magnetically polarized bar code bands are REFERENCE TO RELATED APPLICATION advanced past the MR sensor heads. The spacing of bands of Reference is hereby made to commonly assigned, copend the magnetic bar code pattern represents the code that is read ing US. patent application Ser. No. 330,887 ?led Oct. 28, out by the spaced apart MR heads. 1994, in the names of Neil Srrrith et al. It is recognized in the prior art that while the use of materials of high magnetic coercivity and remanence in 10 magnetic bar code or authentication patterns hidden in the FIELD OF THE INVENTION substrate is therefore advantageous, the persisting remanent magnetic ?eld can be read out with comparable systems or The present invention relates to a security device and the pattern duplicated by anhysterectic duplication. Consid system for encoding documents with code patterns, and erable effort has been expended in schemes for blocking particularly magnetic bar code patterns or other indicia unauthorized duplication or decoding of the hidden bar code exhibiting zero remanence. due to this possibility. For additional security, it has been suggested to provide DESCRIPTION OF THE BACKGROUND ART mixtures of high and relatively low coercivity magnetic materials in the same or in separate bar code bands of the bar 20 In recent years, counterfeiting or falsi?cation of docu codes and to provide more complex read heads. For ments including currency, checks, pre-paid tickets or debit example, the high coercivity bands or band materials may be cards, credit cards, ID cards, passports, security passes, magnetically polarized in different directions than the polar licenses and the like, and their theft and misuse has prolif ization of lower coercivity material bands. Such a security erated. Security systems for incorporation into such docu system is disclosed in the above-referenced ’196 patent ments involve the incorporation of encoded data, either 25 employing a plurality of read heads and a threshold com visibly or invisibly or both, into or on the document sub parison circuit for differentiating the bands. strate and a system for reading out the encoded data to In U.S. Pat. No. 4,982,076, it is also proposed that the bar authorize use of the document. In documents for general code be formed with bar code bands of differing magnetic circulation or dispensation, e.g. currency, pre-paid tickets 30 coercivity levels, as well as of a non-magnetic material as a and the like, the document incorporates a security pattern “dummy” band that cannot be magnetized and read out e. g. a bar code pattern hidden from view. Other personalized magnetically. The medium and high coercivity materials are documents, intended to be used only by an authorized user, stated to be of the types listed above. The lowest coercivity incorporate visible user identi?cation and limits of use data materials include Fe powder, Sendust alloy powder, Mo~ and other data stored magnetically. Cash cards, for example, 35 permalloy powder, Mn-Zn ferrite, Ni-Zn ferrite, Cu~Zn include card visible data as well as identifying data stored in ferrite or the like. a magnetic stripe and require entry of a user selected The high coercivity bar code band is magnetized in a personal identi?cation number (PIN) to be compared to the permanent magnetic state that is unaffected during read out. PIN entered by the user before the card is accepted and the During magnetic reading of the bar code bands by a mag transaction requested is authorized. 40 netic read head, the low, medium and high coercivity bar To increase the security of such documents, from coun code bands are stated to be detectable, and as a result that the terfeiting or unauthorized use, it has also been proposed to state of the high coercivity bar code band can be read out. incorporate a magnetic stripe bar code or other pattern Only the medium and high coercivity bands retain residual visible on or hidden within the document substrate that is magnetization after read out that can be later detected by a read out by a magnetic head. Bar codes formed of magnetic magnetic viewer. Therefore, the actual code is at least partly ink have advantages over optical bar codes, ?rst because the undecipherable, since an attempt to magnetically view the pattern can be hidden from view and second because the bar code pattern will result in an inaccurate reproduction of magnetic pattern does not deteriorate with wear of the only the high and medium bar code bands of the bar code document, which can lead to smearing of the optical bar pattern. code or pattern. Systems for reading visible magnetic bar 50 code or other codes used on checks, can also be reliably operated at high rates of speed, which is important in such Problems to be Solved by the Invention high volume operations as clearing checks. In this regard, the magnetic materials employed in mag There remains a need for a security pattern, e.g. a mag netic bar code, that is not visible to the eye or readily viewed netic inks, e.g. Fe3O4, for use on banknotes, checks, and 55 certain credit cards, typically have medium magnetic coer by a magnetic viewer for use with currency, credit and debit civity of 80-300 Oe. Magnetic materials for other credit cards, stock certi?cates and bonds, and other such docu ments susceptible to counterfeiting or illegal use and a cards, e.g. BaFeuOl9 or SrFe12O19, have a high magnetic system for reading such a pattern in verifying authenticity or coercivity on the order of 3000 Oe. In both cases, the authorized use. encoded magnetic pattern can be magnetized as the docu 60 ment is moved past a magnetic ?eld, and then the magne tization pattern can be read out by an adjacent read head or SUMMARY OF THE INVENTION spaced heads as shown, for example, in US. Pat. No. 4,863,196. The high remanence allows for the heads to be It is therefore an object of the present invention to provide less sensitive. Conventional inductive heads can be used to 65 such a magnetic code pattern and system for reading the both detect the magnetic pattern and read out the recorded code pattern that is not visible to the eye or a magnetic code. viewer. 5,616,911 3 4 In accordance with the invention, it is realized that low FIG. 3 is a diagrammatic view of a read only, magnetic concentrations of magnetic materials having essentially zero security system employing the zero remanence bar code remanence may be employed to provide a code pattern or pattern in accordance with the present invention; indicia on or in a document or card that can be read out with FIG. 4 is a diagrammatic perspective view of an in-?eld a specialized read head for veri?cation purposes. The code magnetoresistive (MR) magnetic read head employed in the pattern is preferably a bar code that is uniquely coded to system of FIG. 3; and identify the speci?c document as an individual document or FIG. 5 is a schematic view of an example of a zero a document type or an authorized user of the document. remanence, magnetic ink, one-dimensional bar code pattern More speci?cally, in one aspect of the invention, a read incapable of being viewed by a magnetic viewer embedded only magnetic security device formed on or in a document within a higher remanence magnetic ink bar code pattern for authenticating the document comprises a document capable of being viewed by a magnetic viewer.
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