Abstract:
An authorization device includes a transponder and antenna. Transmission prompts are received by the antenna and sent to the transponder. The transponder will then emit an identification signal utilized to verify and provide access to a locking device. The antenna is selectively connected to the transponder to control receipt of the transmission prompt. The example authorization device controls receipt of transmission prompts by a transponder to prevent unauthorized and undesired receipt and thereby transmission of identification and other signals.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 60/814,750 filed on Jun. 19, 2006. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    This invention generally relates to a lock for a key including a radio frequency identification tag. More particularly, this invention relates to a security feature for preventing unauthorized interception of a key identification code. 
         [0003]    Radio frequency identification (RFID) tags are electronic devices that transmit an identification signal in response to a transmission received from another source. A typical RFID tag does not require batteries because energy from the prompt transmission is utilized to send the response signal. As no batteries or other power source is required, RFID tags are increasingly being utilized in security applications. 
         [0004]    One such application includes an RFID tag disposed within a key for receiving a transmission from a door lock. The door lock transmits a prompt signal that is received by the key. The RFID tag within the key in turn transmits a signal that is received by the lock. The lock uses the signal from the key to verify that that particular key is authorized to operate the lock. Further, the signal from the key can also be utilized to determine which key is being utilized to compile a record of keys, and in turn which user has operated a particular lock. 
         [0005]    Disadvantageously, the RFID tag within the key will respond to a prompt signal of a particular modulation and frequency, regardless of whether or not that prompts transmission is actually from the lock or from another source. Therefore, an unauthorized prompt transmission could prompt transmission of a particular key&#39;s identification information at a substantial distance. That identification information is then potentially susceptible to unauthorized duplication and use. 
         [0006]    Accordingly, it is desirable to develop and design a device that prevents the receipt and transmission of RFID tag data until desired for operation. 
       SUMMARY OF THE INVENTION 
       [0007]    An example authorization device includes a transponder and antenna. Transmission prompts are received by the antenna and sent to the transponder. The transponder will then emit an identification signal utilized to verify and provide access to a locking device. The antenna is selectively electrically connected to the transponder to control receipt of a transmission prompt. 
         [0008]    A disclosed example authorization device is a key that includes the transponder that is capable of transmitting a radio frequency identification tag in response to receipt of a transmission prompt from a transmitter associated with a lock or other authorized device. The transmission prompt is received by the antenna, and the antenna is selectively engageable such that transmission prompts cannot be received until required for use. 
         [0009]    A circuit within the authorization device is in a default open condition such that no transmission prompt can be received by the transponder. A switch is selectively actuated to allow communication of transmission prompts with the transponder. The transponder will then proceed to transmit the radio frequency identification (RFID) tag data to confirm authorization and allow opening of the lock. 
         [0010]    In another disclosed example, the authorization device includes a shield that prevents receipt of transmission prompts. The shield moves away to expose the RFID tag to transmission prompts once inserted in the lock assembly or when it is desired to receive transmission prompts. 
         [0011]    Accordingly, the example authorization device controls receipt of transmission prompts by a transponder to prevent unauthorized and undesired receipt and thereby transmission of identification and other signals. 
         [0012]    The features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1 , is a schematic view of an example RFID tag key including a selectively engageable antenna. 
           [0014]      FIG. 1A  is schematic view of another example RFID tag key including a selectively engageable antenna. 
           [0015]      FIG. 2 , is a schematic view of another example RFID tag key including a selectively engageable antenna. 
           [0016]      FIG. 3  is a schematic view of an example RFID tag key including a shielded antenna. 
           [0017]      FIG. 4  is a front view of the example RFID tag key including the shielded antenna. 
           [0018]      FIG. 5  is a schematic view of the example RFID tag key with the shield retracted. 
           [0019]      FIG. 6  is a schematic view of another example RFID tag key including a selectively engageable antenna partially inserted into a key hole. 
           [0020]      FIG. 7  is a schematic view of the example RFID tag key of  FIG. 5  completely received within the key hole. 
           [0021]      FIG. 8  is a schematic view of another example RFID tag key including a selectively engageable antenna partially inserted into a key hole. 
           [0022]      FIG. 9  is a schematic side view of the example RFID tag key of  FIG. 8  received into the key hole. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    Referring to  FIG. 1 , a key  10  includes a transponder  14  that transmits data in response to receipt of a transmission prompt from a transmitter associated with a lock or other authorized device (not shown). The transmission prompt is received by an antenna  12 . The antenna  12  includes a coil of wire that is in electrical communication with the transponder  14 . The transponder  14  and antenna  12  comprise a circuit  20  that is disposed within a housing  24 . In the disclosed example, the circuit  20  comprises a single substrate  15  including the transponder  14  and the antenna  12 . The example substrate  15  is flexible, however other circuit substrates as are known are within the contemplation of this invention. The key  10  includes a shank  26  that includes a configuration that corresponds to a key hole of a lock. 
         [0024]    The term transponder as utilized in this disclosure refers to the device or devices that receive an RF signal and produce an RF signal in reply. The example transponder  14  is powered by the RF signal; however it is within the contemplation of this invention to use a transponder including a dedicated power supply such as a battery, for example. 
         [0025]    The antenna  12  is selectively engageable such that transmission prompts cannot be received until required for use of the key  10 . The circuit  20  is in a default open condition such that no transmission prompt can be received by the transponder  14 . That is no transmission prompt can be received until an electrical connection is made between a first contact  16  and a second contact  18 . The electrical connection, in this example, between the first and second contacts  16 ,  18  is provided by a user&#39;s finger  22 . During operation of the key  10  a user grips the key in a manner such that the user&#39;s finger  22  contacts both the first contact  16  and the second contact  18 . The contact with the user&#39;s finger  22  completes the circuit  20 , allowing receipt of the transmission prompt by the transponder. The transponder  14  will then proceed to transmit the radio frequency identification (RFID) tag to confirm authorization and allow opening of the lock. 
         [0026]    Referring to  FIG. 1A , the key  10  includes the first contact  16  on a side opposite the second contact  18 . As appreciated, two fingers are then required to complete circuit  20 . Because the contacts  16  and  18  are disposed on opposite sides of the housing  24 , errant contact by an electrically conductive object such as another key or key ring is less likely to inadvertently complete the circuit to open the key  10  to receipt of transmission prompts. 
         [0027]    Referring to  FIG. 2 , another RFID tag key  30  includes a button  32  that is depressed by a user to complete the circuit  20  and activate the antenna  12 . The circuit  20  remains in an open position until such time as a user desires to use the key  30 . At that time, depressing the button  32  causes the engagement of a contact  34  across the first and second contacts  16 ,  18  to complete the circuit and allow receipt of the transmission prompt. With the button  34  in the default open position, the circuit  20  remains open and no transmission prompt can be received. Thereby, unauthorized or undesired transmission prompts cannot cause the transponder to send a signal that can be intercepted and utilized in an undesirable and unauthorized manner. 
         [0028]    Referring to  FIG. 3 , another RFID key  40  includes an electromagnetic frequency (EMF) shield  42  that prevents the receipt of transmission prompts. In the disclosed example, the EMF shield  42  surrounds the antenna  12  on all sides but for along an axis  44  of the key  40 . 
         [0029]    Referring to  FIG. 4 , in the disclosed example, the EMF shield  42  surrounds the shaft  26  and the antenna  12  within the housing  24 . The EMF shield  42  is disposed substantially concentric about the axis  44 . The EMF shield  42  blocks transmission prompts from being received and thereby prevents undesired transmission from the transponder  14 . 
         [0030]    Referring to  FIG. 5 , the EMF shield  42  is movable upon insertion of the key into a lock housing  58 . With the EMF shield  42  slide out of blocking position, transmission prompts from the lock are receivable. Upon removal of the RFID key  40  from the lock, the EMF shield  42  slides back into blocking position to prevent undesired communication with the transponder  14 . In the illustrated example, the EMF shield  42  moves responsive to being received within the lock housing  58 . The EMF shield  42  may also be movable when removed from the lock by positively moving the EMF shield  42 . However, in a passive condition, the EMF shield  42  would remain in the extended and blocking conditions. 
         [0031]    Referring to  FIG. 6 , another RFID key  50  includes a shank  54  extending from a housing  52 . The shank  54  is received within a key hole opening  56  of a lock housing  58 . The shank  54  includes a button  60  that engages an inner surface  55  of the opening  56  to complete the circuit between the antenna  12  and the transponder  14 . The antenna  12  and transponder  14  are not in electrical communication in a default condition. Accordingly, transmission prompts are not received in this default condition. 
         [0032]    Referring to  FIG. 7 , the shank  54  is shown received more completely within the key hole  56 , such that the button  60  is depressed responsive to contact with the inner surface  55 . In this way, the key  50  is only able to receive transmission prompts when received within the lock, and thereby, substantially prevents unauthorized or undesired receipt and transmission of identification signals. 
         [0033]    Referring to  FIG. 8 , another example RFID key  68  is shown and includes a first contact  76  and a second contact  78  that are in a default open condition; such that transmission prompt signals are not receivable by the antenna  12 . The key  68  includes a shank  74  extending from a housing  72 . The first and second contacts  76 ,  78  are disposed on the outside surface of the shank  74 . The circuit between the transponder  14  and the antenna  12  remains open until such time as the contacts  76 ,  78  are closed. The key hole  56  includes a contact surface  70  that corresponds with key contacts  76 ,  78 . 
         [0034]    Referring to  FIG. 9 , the disclosed key  68  is shown received within the key hole  56  such that the first and second contacts  76 ,  78  are engaged with the contact surface  70  to complete the circuit within the key  68 . In this position, the key  68  is ready and capable of receiving transmission prompts. Once the transmission prompts are received the transponder  14  is free to send the identification code for receipt by the lock. 
         [0035]    Accordingly, the example key according to this invention provides a selectively engageable antenna to prevent unauthorized and undesired receipt and thereby transmission of identification and other signals. 
         [0036]    Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.