Abstract:
Methods and apparatus are provided for rendering electronic keys left behind in a vehicle temporarily inactive. The apparatus comprises a vehicle security control module in wireless communication with the electronic keys, and having operatively coupled together a receiver, a processor, non-volatile memory and a short-range transmitter. When the module receives a valid lock command from any source it sends a short-range interrogation signal to keys within the vehicle. Left-behind keys respond and send their unique ID(s) to the module&#39;s receiver. The processor obtains the unique ID(s) from the receiver and sets one or more inhibit flags in memory or equivalent to identify those keys as left-behind keys. The processor thereafter ignores commands from such left-behind keys, thereby rendering them temporarily inoperative until a valid unlock command is received form another source, whereupon the processor clears the inhibit flags from memory and restores the left-behind keys to active status.

Description:
TECHNICAL FIELD  
       [0001]     The present invention generally relates to electronic locking systems and keys therefore, and more particularly relates to means and methods for rendering electronic keys for such systems temporarily valid or invalid.  
       BACKGROUND  
       [0002]     There are many applications today where electronic keys are used. A common example is with vehicles where an electronic key, sometimes in the form of a “fob” is enabled by the user to lock and unlock the vehicle doors, trunk, etc., raise and lower windows, start and stop the engine and/or perform a variety of other functions. Such systems are well known in the art.  
         [0003]     The present invention is described for the case of electronic keys used to authorize vehicle door access, trunk access, and starting, but this is merely for convenience of explanation and not intended to be limiting. Persons of skill in the art will understand based on the description herein that the present invention applies to any electronic key function and not merely to a “lock” and “unlock” function and not merely to vehicles. Hence, such other electronic key functions are intended to be included in the words “lock” and “unlock” and such other locations, equipment, structures and/or apparatus are intended to be included in the word “vehicle.” 
         [0004]     While prior art electronic keys and key systems are useful, they suffer from a number of limitations, well known in the art. Among these limitations is the presence of multiple keys. For example, when multiple keys exist and one or more is left behind in the vehicle (or structure), security can be compromised if an unauthorized person gains access to the “left-behind” key. Even if the vehicle is locked if there is an unauthorized entry and the intruder gains access to the left-behind key, he or she may be able to open doors, turn off a security alarm, start the vehicle or otherwise perform those functions able to be controlled by the left-behind key. Thus, a need continues to exist for improved systems and methods for dealing with multiple keys so that left-behind or other temporarily un-needed keys do not represent a security risk.  
         [0005]     Accordingly, it is desirable to provide an improved electronic locking and key system and method that mitigate the risk presented by left-behind keys or other keys whose use may be compromised. It is desirable that the system be able to temporarily invalidate electronic keys that are left-behind or that otherwise present a security risk. In addition, it is desirable that the improved system and method be generally compatible with prior art electronic key systems. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.  
       BRIEF SUMMARY  
       [0006]     An apparatus is provided for rendering electronic keys left behind in a vehicle temporarily inoperative. The apparatus comprises a vehicle security control module in wireless communication with the electronic keys and having a receiver adapted to receive commands from electronic keys, a processor, non-volatile memory and a short range transmitter, operatively coupled together. When the security module receives a valid LOCK command from any source it sends a short-range interrogation signal to any keys within the vehicle. Such left-behind keys respond and send their unique ID(s) to the module&#39;s receiver. The processor obtains the unique ID(s) from the receiver and sets one or more inhibit flags in memory to identify those as left-behind keys. The processor thereafter ignores commands or signals from such left-behind keys, thereby rendering them temporarily inactive. Such left-behind keys remain inactive until a valid UNLOCK command is received form another source, whereupon the processor clears the inhibit flags from memory and restores the left-behind keys to active status.  
         [0007]     A method is provided for rendering electronic keys left behind in a vehicle temporarily inoperative. The method comprises receiving a LOCK command, sending a short range interrogation signal from the vehicle security control module to any keys left behind in the vehicle, receiving from any left-behind key(s) their unique ID(s), and setting one or more inhibit flags for the unique ID(s) of the left-behind keys, wherein the inhibit flags cause the vehicle to temporarily ignore further commands or signals received from such left-behind key(s). The left-behind keys remain invalidated until an UNLOCK command is received from other than an invalidated key and the one or more inhibit flags are cleared, thereby returning the left-behind keys to operating status. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and  
         [0009]      FIG. 1  is a simplified electrical block diagram of the system of the present invention; and  
         [0010]      FIG. 2  is a simplified flow chart of the method of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0011]     The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.  
         [0012]      FIG. 1  is a simplified electrical block diagram of system  20  of the present invention, comprising security control module  41  in the vehicle (or structure) and one or more portable electronic keys  21  that may or may not be in the vehicle (or structure). Keys  21  comprise processor  22 , non-volatile memory  24 , other memory  25 , transmitter  26  and receiver  28 , operatively coupled by bus or leads  23 . A state machine or other device may also be used as a replacement for processor  22  and as used herein the word “processor” is intended to include such alternative. Antenna  27  is provided for transmitter  26  and antenna  29  is provided for receiver  28 . Keys  21  communicate with vehicle security control module  41  via signals  33 ,  35  from and to antennas  27 ,  29  respectively. Transmitter  26  of key  21  and receiver  46  of security control module  41  operate preferably at radio frequencies (RF). Thus, signal  33  is preferably an RF signal. Receiver  28  of key  21  and transmitter  48  of vehicle security module  41  operate preferably at low frequencies (LF). Thus, signal  35  is preferably a LF signal. However, the use of RF and LF signals is not essential. Other frequencies may also be used, provided that signal  35  is limited in range, as will be explained in more detail later. Non-limiting examples of suitable frequencies are 300 to 500 MHz for signal  33  and 100 to 150 KHz for signal  35 , but this is not intended to be limiting. Optical signals may also be used. For example, low power infrared may also be used for signal  35 .  
         [0013]     Vehicle mounted security control module  41  comprises processor  42 , non-volatile memory  44 , other memory  45 , receiver  46 , transmitter  48  and actuator(s)  50 , operatively coupled by leads or bus  43 . Antenna  47  is provided for receiver  46 , which receives signals  33  from antenna  27  and transmitter  26  of key  21 . Antenna(s)  49  are provided for transmitter  48 , which sends signals  35  to antenna  29  of receiver  28  of key  21 . Further LOCK/UNLOCK request sources  51  are coupled to control module  41  by leads or bus  52  and/or by wireless signal  53 . Non-limiting examples of further LOCK/UNLOCK request sources  51  are central door lock switches, passive door lock switches, telematic services, key activated lock cylinders, alarm system activation/de-activation switches, and so forth.  
         [0014]     In one manner of ordinary operation, activation of function buttons (not shown) on electronic key  21  by the user causes processor  22  of key  21  to retrieve the appropriate command code (e.g., LOCK, UNLOCK, etc.) and the key identification code (unique key ID) from non-volatile memory  24 . Persons of skill in the art will understand that a variety of operator selected functions may be included in key  21 . Processor  22  prepares a signal containing these codes in the appropriate format and passes it over bus or leads  23  to transmitter  26  where it is modulated onto an appropriate (e.g., RF) carrier by transmitter  26  and sent as signal  33  via antenna  27  to antenna  47  and receiver  46  of control module  41 . Receiver  46  demodulates signal  33  and passes the recovered command and identification codes over bus or leads  43  to processor  42 . Processor  42  compares the received key ID code with valid key ID codes stored in memory  44  and, if approved, causes actuator(s)  50  to execute the command received from key  21 . Thus, among other things, processor  42  in cooperation with memory  44 ,  45  and receiver  46 , checks any signals received from key  21  to insure that the ID of the transmitting key corresponds to a key authorized to issue commands to the particular vehicle.  
         [0015]     Consider the situation where several valid keys  21  exist, that is, more than one key is authorized to control vehicle functions via security control module  41 . The user may take only one key with him/her when he or she exists the vehicle. One or more of the other keys are left behind in the vehicle. The portable key(s) are not the only mechanisms or circumstances able to lock or unlock the vehicle. In general, other lock/unlock request sources  50  are often coupled to the vehicle. For example, and not intended to be limiting, the vehicle may be locked or unlocked by: 
        a) Activation of a central locking request from the vehicle interior;     b) Transmission of a “lock” command from nearby portable device such as key fob  21 ;c)     c) Transmission of a “lock” command from a remote service provider (e.g., one of several lock/unlock request sources  50 );     d) Activation of a central locking request from a vehicle mounted exterior switch (e.g., another of several lock/unlock request sources  50 ); and/or     e) Passive locking upon detection of a reduction in electronic keys present in the vehicle&#39;s interior. 
 
 It is desirable that the left-behind key or keys be rendered temporarily inactive so as to not constitute a potential security risk to the vehicle. This is accomplished by the present invention 
       
 
         [0021]     When any lock activation, such as those listed above, is requested or occurs when the vehicle is in an OFF mode of operation, vehicle mounted security control module  41  determines whether any electronic keys  21  have been left in the vehicle. Alternatively, the vehicle alarm system status (e.g., one of sources  50 ) may be used as a surrogate for a lock and/or unlock commands, i.e., an ALARM ON command or status is equivalent to a LOCK command. Determining whether any keys remaining the vehicle is conveniently accomplished by processor  42  causing transmitter  48  to send interrogation signal  35  to keys  21  within range, that is, still within the vehicle. Having transmitter  48  be a low frequency (LF) transmitter limits the range of transmitter  48  so that only keys  21  that are still within the vehicle receive interrogation signal  35 . When a key receives such an interrogation signal, it responds acknowledging its continuing presence in the vehicle and giving its unique ID. Depending upon the vehicle configuration, it may be advantageous to use several antennas  49  to provide interior vehicle coverage while still having negligible transmission field outside the vehicle. When control module  41  receives a response or acknowledgement signal from key transmitter  26  containing the unique ID of that key, it knows that such key has been left behind in the vehicle. For each key  21  that has been left in the vehicle, processor  42  causes an inhibit flag or other marker to be set in memory  44  to identify the left-behind key as temporarily invalid. Flag storage is performed in non-volatile memory  44  to ensure proper security is maintained over time and voltage levels.  
         [0022]     As long as this inhibit flag remains set, the vehicle will not respond to commands from that portable key. For each normal access or vehicle operation request where any electronic key  21  is detected and has passed the normal ID and/or other authentication process, a further check is made of its flag to determine if it is temporarily invalid. If the inhibit flag or other marker is set indicating that the key is invalid, no vehicle action will result. If the inhibit flag or other marker is not set, the corresponding function will be appropriately performed. In the preferred embodiment, upon receipt of an authenticated unlock request from any electronic key  21  that has been deemed to be also a valid key (ID match; no flag set, etc.) or from any other allowed unlock request source, the inhibit flags for all other electronic keys programmed to the vehicle will be cleared, thereby re-validating them all for subsequent use. The operation of system  20  will be more fully understood by reference to the method of the present invention illustrated in  FIG. 2 .  
         [0023]      FIG. 2  is a simplified flow chart of method  100  of the present invention. Method  100  begins with START  102  and initial COMMAND RECEIVED FROM KEY? query  104 . START  102  provides for initialization of system  20  in the key inhibit mode and desirably occurs when the ignition is switched off or the vehicle otherwise placed in the OFF state. In initial query  104  it is determined whether or not the vehicle has received a command from one of keys  21 . If the outcome of query  104  is FALSE (NO), abbreviated “N”, then method  100  advances to VALID LOCK COMMAND FROM VEHICLE? query  106  wherein it is determined whether or not a valid lock command has been received from the vehicle, e.g., from one of other lock request sources  51 . If the outcome of query  106  is FALSE (NO) then, as shown by path  107 , method  100  loops back to START  102  and initial step  104 . If the outcome of query  104  is TRUE (YES), abbreviated as “Y”, then method  100  proceeds to KEY&#39;S INHIBIT FLAG SET? query  108  wherein it is determined whether the key issuing the command referred to in step  104  has its inhibit flag set, to inactivate such key. If the outcome of query  108  is TRUE (YES), then as shown by path  109 , method  100  loops back to START  102  and initial query  104 . This has the effect of ignoring commands received from a key whose inhibit flag is set while preparing to accept a valid command that originates other than from such portable key  21 .  
         [0024]     If the outcome of query  108  is FALSE (NO) meaning that the command issuing key is not inhibited, method  100  proceeds to RECEIVED COMMAND=LOCK? query  110  wherein it is determined whether the received command is a LOCK command. If the outcome of query  110  is TRUE (YES), then method  100  advances to SEND QUERY TO INSIDE KEYS step  112 , wherein security control module  41  sends localized interrogation or query signal  35  to one or more keys  21  that are within the vehicle. Those of keys  21  that are within the vehicle respond at least with their unique IDs. Module  41  then executes ANY KEYS LEFT BEHIND? query  120  to determine which, if any, of keys  21  have been left behind in the vehicle. Returning to query  106 , if the outcome of query  106  is TRUE (YES) indicating that security module  41  has received a valid LOCK command from a key  21  or another lock request source  51 , then method  100  also advances to interrogate step  112  and query  120 . Thus, if a LOCK command or request is received from either keys  21  or from another source  51 , method  100  will determine whether any other of keys  21  have been left behind in the vehicle, and through their unique IDs, which of keys  21  have been left behind in the vehicle. If the outcome of ANY KEYS LEFT BEHIND? query  120  is TRUE (YES), method  100  advances to INHIBIT LEFT-BEHIND KEYS step  122  wherein the keys identified in steps  112 ,  120  have their inhibit flags set so that they are no longer functional in whole or in part. After step  122 , method  100  advances to EXECUTE COMMAND step  116 . If the outcome of ANY KEYS LEFT BEHIND? query  120  is FALSE (NO), then method  100  proceeds to EXECUTE COMMAND step  116  wherein the received and authenticated command is executed.  
         [0025]     Returning now to query  110 , if the outcome of query  110  is FLASE (NO) indicating that the received command was not a LOCK command, then method  100  proceeds to RECEIVED COMMAND=UNLOCK? query  114  wherein it is determined whether the received command is an UNLOCK command. If the outcome of query  114  is FALSE (NO), then method  100  also proceeds to EXECUTE COMMAND step  116 . (This deals with the circumstance where the received command is neither a LOCK nor UNLOCK command.) If the outcome of query  114  is TRUE (YES) indicating that the received command is an UNLOCK command, then method  100  proceeds to CLEAR INHIBIT(S) step  118 , wherein any inhibit flags previously set are cleared, thereby returning the corresponding key(s) to active status. Following step  118 , method  100  proceeds to EXECUTE COMMAND step  116  and thereafter loops back to START  102  as shown by path  117 .  
         [0026]     In summary, a LOCK command causes control module  41  to interrogate those of keys  21  that may have been left behind in the vehicle and inhibits them from performing all or some of their normal functions until a valid UNLOCK command has been received from another source. The inhibit is conveniently accomplished by placing a flag or other marker in non-volatile memory in control module  41 , but any other means of accomplishing an equivalent inhibit result may also be used. A non-limiting example of an alternate arrangement is to send an inhibit command back to the inside-the-vehicle keys using signal  35  and storing the inhibit flag in memory  24  within the inhibited keys themselves. With this arrangement, each key would check its own inhibit flag before sending a command to module  41  and if the flag is set, not transmit to module  41  until its inhibit status is cleared. The same result is accomplished in that inhibited keys are inactivated until module  41  sends out signal  35  containing a CLEAR INHIBITS command to affected keys  21 .  
         [0027]     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. For example, inhibiting the left-behind keys by setting a flag in memory is but one of many ways in which the left behind keys may be rendered temporarily inactive. Accordingly, the words “setting a flag in memory” and “storing one or more inhibit flags” or equivalent are intended to include such alternative arrangements for temporarily invalidating the left-behind keys. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.