Abstract:
An RFID shield in the form of a thin plastic substrate upon which a shielding pattern is printed in conductive paint or ink. The pattern may cover the entire surface of the substrate or it may be in the form of intersecting lines or arrays of intersecting elements.

Description:
[0001]    The present application claims priority from the following applications: Application 61/979,397 filed 14 Apr. 2014; Application 62/033,063 filed 4 Aug. 2014; Application 62/033,082 filed 4 Aug. 2014; Application 62/033,074 filed 4 Aug. 2014; Application 62/033,085 filed 4 Aug. 2014 and Application 62/033,078 filed 4 Aug. 2014. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Radio frequency identification (RFID) chips are increasingly found embedded in various devices including credit cards, driver licenses, passports, etc. Such chips contain a significant amount of personal data such as the holder&#39;s name, address, social security number, account information, employee number and the like, which is of high value to identity thieves. There are available devices which can be utilized to read such data from as far as 10 feet or so. Unfortunately, when such devices fall into the hands of unscrupulous people, they enable the undetected reading of such data from unsuspecting victims in public places such as malls, coffee shops etc. Upon harvesting the data on a holder&#39;s card, the identity thief is able to program the data on its own card thereby enabling the thief&#39;s cloned card to respond in an identical fashion as the holder&#39;s legitimate card. 
         [0003]    Heretofore it has been suggested to provide shielding to prevent the unauthorized reading of RFID chips, in the form of metallic cases, which, while effective, are awkward and cumbersome to carry and use. It is thus a principal object of the present invention to provide effective and efficient RFID shielding in a form that may be conveniently and comfortably carried in a user&#39;s pocket, purse or wallet.  
       SUMMARY OF THE INVENTION 
       [0004]    In accordance with the present invention, the above and other beneficial objects are attained by providing an RFID shield in the form of a substrate upon which a shielding pattern is printed in conductive paint or ink. The pattern may cover the entire surface of the substrate or it may be in the form of intersecting lines or arrays of intersecting elements. The pattern may be in the form of a spiral antenna, a patch antenna, a fractal antenna or a combination of a spiral, patch or fractal antenna. The antenna may be passive or made active by providing a lithium flat pack battery and piezoelectric elements to charge the battery based on normal movement of the user. Alternatively, the shielding may be provided by a smartphone app utilizing the near field communication (NFC) hardware and high speed receiver sections in the phone to detect when a surreptitious signal is being read and to generate a bogus signal in response. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    In the accompanying drawings: 
           [0006]      FIG. 1  is an exploded plan view of a stack of RFID credit cards sandwiched between a pair of RFID shields in accordance with the present invention. 
           [0007]      FIG. 2  is an end view of the stack of RFID credit cards sandwiched between a pair of RFID shields; 
           [0008]      FIG. 3  is first embodiment of a conductive pattern printed on a plastic substrate of the RFID shield; 
           [0009]      FIG. 4  is an alternative conductive pattern; 
           [0010]      FIG. 5  is another conductive pattern; 
           [0011]      FIG. 6  is another conductive pattern; 
           [0012]      FIG. 7  is a partial side view of the RFID shield of the present invention provided with non-conductive protective sheets; 
           [0013]      FIG. 8  is plan view of a RFID shield wherein the printed conductive pattern is in the form a spiral and a fractal antenna; and, 
           [0014]      FIG. 9  is a plan view of a powered RFID shield. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    Reference is now made to the drawings and to  FIGS. 1 and 2  in particular wherein a stack of credit cards  10  is shown. The stack of cards  10  may be sandwiched between a pair of RFID shields  12  although a single shield has been found to provide effective protection even when the stack of cards is offset as in a billfold. While the stack is shown as consisting of two credit cards  10 , it may comprise a lessor or greater number. Each of the shields  12  comprises a substrate  14  printed with a conductive ink or paint. Such inks are readily available from several sources including E. I. du Pont Nemours and Company. The substrate is a relatively thin plastic sheet, either thermoplastic or thermosetting of credit card size and between 0.5 and 50 mils thick. The substrate may be covered with the conductive ink or the conductive ink may be printed or silk screened with a pattern  16  comprising cross hatched intersecting uninterrupted lines as shown in  FIG. 3  or elements  18 ,  20 ,  22  arranged in an intersecting array. To protect the conductive ink, the printed substrate  14  may be covered with a thin plastic non-conductive sheet  24  or laminated between thin plastic non-conductive sheets  24 . The sheet or sheets  24  may carry a logo or graphics. Alternatively, the protective layer may be a non-conductive paint or ink layer. The conductive ink/paint may be solvent or UV curable, loaded with silver, carbon or other conductive material to provide a conductivity of between 0.01 to 50 ohms/square. 
         [0016]    For more effective shielding, the printed conductive pattern  16  may be in the form of an antenna  26  as shown in  FIG. 8 . In this case, the pattern functions as an antenna system receiving incident electromagnetic energy from an interrogation transmitter effectively eliminating the possibility of the RFID chip on a protected card communicating with the interrogation device. In this case, the pattern  16  is configured as a spiral antenna as shown in  FIG. 8 . Alternatively, the conductive layer may be configured as a patch antenna, a fractal antenna or a combination of a spiral, patch or fractal antenna. 
         [0017]    The shielding described above may be considered to be passive. Alternatively, the shield  12  may be made active by providing a high speed receiver section  32  attached to antenna  26 , which includes a spiral transmit/receive antenna  28  and a fractal patch antenna  30 . When the high speed receiver section  32  detects attempt to interrogate the protected RFID chip it transmits a jamming signal. The shield is powered by a flat pack lithium battery which may be kept charged through normal motion of the device while in a user&#39;s wallet or purse through a pair of piezoelectric charging components  40 . Similarly, since today&#39;s smartphones contain embedded Near Field Communication (NFC) hardware, by placing the smartphone in proximity with the RFID chips to be protected an app may be provided to utilize the high speed receiver section within the phone to detect attempts to interrogate the RFID chips being protected. The app will poll for RFID read attempts and when an interrogating signal is detected, the smartphone will transmit a jamming signal consisting of bogus data thereby protecting both the RFID chip data as well as any data on the phone. The app can be shut off for NFC communication when desired. 
         [0018]    Thus, in accordance with the above, the aforementioned objectives are effectively attained.