Abstract:
A method to deactivate a security measure includes applying a first covert optically active security marker to a product or document; completing a transaction for the product or document; and applying a second optically active security marker to the product or document which indicates completion of the transaction.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Reference is made to commonly-assigned copending U.S. patent application Ser. No. ______ (Attorney Docket No. K000025US01/NAB), filed herewith, entitled IMAGE ALGORITHMS TO REJECT UNDESIRED IMAGE FEATURES, by Widzinski et al.; and U.S. patent application Ser. No. ______ (Attorney Docket No. K000212US01/NAB), filed herewith, entitled METHOD OF AUTHENTICATING SECURITY MARKERS, by Widzinski et al.; the disclosures of which are incorporated herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates in general to traceless security marker and in particular to deactivating traceless security markers. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is sometimes useful to be able to deactivate a security measure during the production, distribution, sale (return), and disposal chain. For example, in retail, security tags that trigger a theft alarm at exit gates are deactivated at the point of sale. Return fraud occurs when items are stolen from a store and then returned for a refund, facilitated by lenient return policies, e.g. no receipt requirement. 
         [0004]    It would be beneficial, therefore, to have a covert deactivation feature in the traceless system to identify an item that has rightfully been paid for. It is possible to remove or obscure the traceless signature by scratching off or adding an absorber, but these measures will likely leave visible marks. 
         [0005]    Some reader based authentication systems expect the marker response of a marked item within both a low and a high limit. See commonly-assigned, copending U.S. patent application Ser. No. ______ (Attorney Docket Nos. K000025US01/NAB and K000212US01/NAB). A method and apparatus are needed to deactivate traceless systems. 
       SUMMARY OF THE INVENTION 
       [0006]    Briefly, according to one aspect of the present invention a means to invalidate an item that is authenticated by an authentication reader is provided. The reader authenticates the item by detecting the presence of a security marker. The invalidation is done by adding an additional marker whose presence will trigger a “fail” response from the authentication reader. The fail response of the reader can be triggered by the transgression of a high limit, by not meeting shape requirements of the marker image (in case of an imaging reader) or by the presence of a different optical response from the added marker. 
         [0007]    The present invention offers a way of deactivating, e.g., a hangtag by adding additional marker (via a spray, pen, or other applicator) such that the marked item will fail “high.” Other possibilities are to add a marker that will trigger false positive aversion mechanisms of the reader, e.g. the shape detection, by adding fibers or flakes or marker specific rejection mechanisms by adding a marker with a different optical response. 
         [0008]    The invention and its objects and advantages will become more apparent in the detailed description of the preferred embodiment presented below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  shows a plan view of a security marker detection system; 
           [0010]      FIG. 2  shows a block diagram of a security marker detection system; 
           [0011]      FIG. 3  shows an alternate embodiment of a security marker detection system; 
           [0012]      FIG. 4  shows an image of an authentic item; 
           [0013]      FIG. 5  shows an image of deactivated authentic item; 
           [0014]      FIG. 6  shows an image of an authentic item; 
           [0015]      FIG. 7  shows an image of deactivated authentic item; and 
           [0016]      FIG. 8  shows a schematic of optoelectronic components of a security marker detection system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    The present invention will be directed in particular to elements forming part of, or in cooperation more directly with the apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. 
         [0018]    Referring now to  FIG. 1  which shows a block diagram of a security marker detection system  10  which can be used to detect emitted or reflected radiation from security marker materials, as required in this invention.  FIG. 1  also shows the item to be authenticated  18 . Authentication is performed by pressing the test button  12 . The result is displayed by either a pass indicator light  14  or a fail indicator light  16 . 
         [0019]    Referring now to  FIG. 2  which shows a schematic representation of a security marker detection system  19  which can be used to detect emitted or reflected radiation from security marker materials in an image-wise fashion, as required in the present invention. One or more irradiation sources  22  direct electromagnetic radiation towards the item to be authenticated  18 . The authentic item contains a random distribution of marker particles  20  either in an ink or in an overcoat varnish. The marker particles emit or reflect electromagnetic radiation  26  as a response to the radiation from the irradiation sources  22  which is detected by a camera  28 . A microprocessor  30  analyzes the camera image and determines a pass or fail indication which is displayed on the authentication indicator  32 . 
         [0020]    Referring now to  FIG. 3  which shows an alternate embodiment of a security marker detection system  39  which can be used to detect emitted or reflected radiation from security marker materials in a non image-wise fashion, as required in the present invention. One or more irradiation sources  22  direct electromagnetic radiation towards the item to be authenticated  18 . The authentic item contains a random distribution of marker particles  20  either in an ink or in an overcoat varnish. The marker particles emit or reflect electromagnetic radiation  26  as a response to the radiation from the irradiation sources  22 , which emits excited electromagnetic radiation  24 , which is detected by a photodetector  40 . A microprocessor  30  analyzes the photodetector response and determines a pass or fail indication which is displayed on the authentication indicator  32 . Pass or fail indication can, for example, represent authentic/active and authentic/deactivated, respectively. 
         [0021]    Referring now to  FIG. 4  which shows an image of an authentic item taken with an authentication reader  19  according to  FIG. 2 . The image contains a random distribution of marker particles  50  with low concentration. The authentication reader will pass this item as authentic/active because pass criteria for concentration of marker particles in the image are met. For a non-imaging authentication reader  39  according to  FIG. 3 , the pass criterion is based on the intensity of the photodetector signal  40 . In this case the marked item will pass as authentic/active because the intensity of the photodetector signal  40  meets the pass criterion. 
         [0022]    Referring now to  FIG. 5  an image of an authentic item taken with an authentication reader  19  according to  FIG. 2  is shown. The authentic marked item  18  was deactivated by adding marker particles  20 . The resulting image contains a random distribution of marker particles  52  with high concentration. The authentication reader will interpret this item as authentic/deactivated because pass criteria for concentration of marker particles in the image are exceeded. For a non-imaging authentication reader  39  according to  FIG. 3 , the pass criterion is based on the intensity of the photodetector signal  40 . In this case the marked item will be interpreted as authentic/deactivated because the intensity of the photodetector signal  40  exceeds the pass criterion. 
         [0023]    Referring now to  FIG. 6  which shows an image of an authentic item taken with an authentication reader  19  according to  FIG. 2 . The image contains a random distribution of marker particles  54  with low spatial density. The authentication reader will pass this item as authentic/active because pass criteria for concentration of marker particles and spatial density of the image are met. 
         [0024]    Referring now to  FIG. 7  which shows an image of an authentic item taken with an authentication reader  19  according to  FIG. 2 . The authentic marked item  18  was deactivated by adding marker particles in a solid contiguous pattern. The resulting image contains an area within the image of marker particles with high spatial density  56 . The authentication reader will interpret this item as authentic/deactivated because pass criteria for spatial density of the marker image are not met. 
         [0025]    Referring now to  FIG. 8  which shows a schematic of an optoelectronic components of a security marker detection system  39  which can be used to detect emitted or reflected radiation from security marker materials in a non image-wise fashion as shown in  FIG. 3 . The optoelectronic components consist of irradiation sources  60   a  and  60   b  that generate different wavelengths of electromagnetic radiation, and a photodetector  40 . The irradiation sources are directed towards a marked item  18  that contains marker particles  62   a  and  62   b  that respond to irradiation sources  60   a  and  60   b,  respectively by emitting or reflecting light. This light is captured by a photodetector. As required in the present invention, the authentication system is designed such that the authentication reader will pass the item as authentic/active when response from marker particle  60   a  is detected. To deactivate the sample, marker particles  60   b  are added to the marked item  18 . The authentication reader will then fail the item as authentic/deactivated when the presence of marker particle  60   b  is detected. It is noted that this situation is clearly distinguished from a case where no marker particles are present at all, or where only marker particle  60   b  is present. These situations can be reported as non-authentic. 
         [0026]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention. For example, markers used to produce marked items include inorganic phosphors and pigments and organic dyes. Markers can be authenticated based on either their emissive or absorptive response to stimulating radiation. 
       PARTS LIST 
       [0027]      10  security marker detection system 
         [0028]      12  button to initiate authentication 
         [0029]      14  authentication indicator pass 
         [0030]      16  authentication indicator fail 
         [0031]      18  marked item to be authenticated 
         [0032]      19  authentication device employing image-wise detection 
         [0033]      20  security marker particle 
         [0034]      22  irradiation source 
         [0035]      24  exciting electromagnetic radiation 
         [0036]      26  emitted electromagnetic radiation 
         [0037]      28  camera 
         [0038]      30  microprocessor 
         [0039]      32  authentication indicator 
         [0040]      39  authentication device employing non image-wise detection 
         [0041]      40  photodetector 
         [0042]      50  marker particle (low concentration) 
         [0043]      52  marker particle (high concentration) 
         [0044]      54  marker particle (low spatial density) 
         [0045]      56  marker particle (high spatial density) 
         [0046]      60   a  irradiation source  1   
         [0047]      60   b  irradiation source  2   
         [0048]      62   a  marker particle  1   
         [0049]      62   b  marker particle  2