Self-contained electronic lock with changeable master and slave codes

An electronic lock comprising:

• an EEPROM for holding a plurality of electronic key codes in a plurality of corresponding address locations;
• means, associated with said EEPROM, for identifying at least one of said plurality of address locations as a master key code address and for identifying at least two of said plurality of address locations as slave key code addresses;
• a master key code being a code that enables changing the contents of at least one of said plurality of address locations, and a slave key code being a code that enables unlocking the lock;
• input means for communication with a key device to receive and temporarily store an electronic key code from said key device;
• comparison means for comparing a received electronic key code with the contents of each of said plurality of address locations to determine whether the received key code corresponds to a key code stored in any of said plurality of address locations;
• and
• means, responsive to said comparison means, for performing predetermined lock-management functions which include the function of:
• substantially entirely erasing the contents of said at least one master key code address location in response to receiving, in a master-code-erasing procedure, the master key code that is stored in said at least one master key code address location, so that at least one particular master key code address location becomes available for any key code from any key device that is subsequently in communication with the input means.

A method of operating an electronic lock system that includes (1) an electronic lock having an erasable memory for storing a set of key codes, said memory including at least one erasable memory location reserved for a master key code, and (2) a plurality of electronic keys each of which holds a substantially unique key code and each of which is for selective engagement and electrical communication with the lock;

• said method being such as to designate any selected one of the keys as a master key;
• a master key being a key that enables changing the contents of at least one of said plurality of address locations;
• said method comprising the steps of:
• manually selecting a key and manually engaging the selected key with the lock;
• and
• in response to that engagement of the selected key with the lock:
• substantially automatically determining whether at least one particular erasable memory location reserved for a master key code is empty, and
• in response to determining that at least one particular erasable memory location is empty, and no matter what key code said selected key has, substantially automatically storing the key code of said selected key in said particular erasable memory location, to identify the thus-stored key code as belonging to a master key.

A method of operating an electronic lock system that includes an electronic lock having an erasable memory for storing a set of key codes, and that includes a plurality of electronic keys each of which contains a substantially unique key code and each of which is for selective engagement and electrical communication with the lock;

• said method being a method of operating the lock system so as to designate a selected key as a master key;
• a master key code being a code that enables changing the contents of at least one key code in said stored set of key codes;
• said method comprising the steps of:
• substantially automatically selecting a key code location in the erasable memory;
• if said selected key code location is not already reserved for a master key code, substantially automatically reserving said selected key code location for a master key code;
• but if said selected key code location is already reserved for a master key code, then not performing said substantially automatically reserving step;
• manually selecting a key;
• manually engaging the selected key with the lock;
• and
• in response to the manually-engaging step:
• substantially automatically determining whether said selected key code location in the erasable memory is empty, and
• in response to a determination that said selected key code location in the erasable memory is empty, and no matter what key code the selected key has, substantially automatically storing the key code of the selected key in said selected master key code memory location, as a master key code.

A method of operating an electronic lock system that includes an electronic lock having an erasable memory for storing a set of key codes, including at least one memory location reserved substantially automatically for a master key code, and that includes a plurality of electronic keys each of which contains a substantially unique key code and each of which is for selective engagement and electrical communication with the lock;

• said method being a method of operating the lock system so as to designate a selected key as a master key;
• a master key code being a code that enables changing the contents of at least one key code in said stored set of key codes;
• said method comprising the steps of:
• substantially automatically selecting a master key code memory location in the erasable memory;
• manually selecting a key;
• manually engaging the selected key with the lock;
• and
• in response to the manually-engaging step:
• substantially automatically determining whether said selected master key code memory location is empty,
• in response to a determination that said selected master key code memory location is empty, and no matter what key code the selected key has, substantially automatically storing the key code of the selected key in said selected master key code memory location.

A method of operating an electronic lock system that includes an electronic lock having an erasable memory for temporarily storing a set of key codes, and that includes a plurality of electronic keys each of which contains a substantially unique key code and each of which is for selective engagement and electronic communication with the lock, and in which the key code of a particular key has already been stored in a memory location reserved for a master key code;

• said method being a method of operating the lock system so as to change from that particular key to a selected new master key;
• a master key code being a code that enables changing the contents of at least one key code in said stored set of key codes;
• said method comprising the steps of:
• manually engaging the particular key with the lock at least three separate times in uninterrupted sequence within a predetermined time interval;
• in response to the sequence of engagements by the particular key, substantially automatically erasing the key code of the particular key from the memory location reserved for a master key code;
• then manually selecting any key to become the new master key;
• thereafter, manually engaging the selected key with the lock;
• and
• in response to said manually-engaging step, substantially automatically storing the key code of the selected key in said memory location reserved for a master key code, so that the selected key becomes the new master key.

An electronic lock for selectively utilizing an electronic key device, which contains a substantially unique key code, as either a slave key or a master key;

• a slave key being a key that enables unlocking the lock, and a master key being a key that enables changing designations of what key devices the lock will recognize as slave and master keys;
• said lock comprising:
• an EEPROM having a plurality of separate address locations for holding a corresponding plurality of electronic key codes, at least one of said address locations being identified as a master key code address and a plurality of other said address locations being identified as slave key code addresses;
• volatile memory means for accepting and temporarily holding an electronic key code;
• input means for communication with an electronic key device and for receiving therefrom during said communication a key code substantially unique to said key device, and for temporarily storing the received key code in said volatile memory means;
• comparison means for comparing the received and temporarily stored key code with the contents of each of said plurality of address locations to determine whether the received and temporarily stored key code is in any of said plurality of address locations;
• means, responsive to a determination by said comparison means that the received and temporarily stored key code is in any of said plurality of address locations, for generating a lock-unlocking signal;
• means for automatically determining whether all of said address locations are empty;
• means for responding to a determination by the determining means that all of said address locations are empty by placing the received and temporarily stored code in a master code address, no matter what that code is, whereby said key device becomes a master key;
• and
• verification means for generating, in conjunction with said placing of said key code by said responding means, an intelligence signal identifying storage of a master key code.

A self-contained electronic lock comprising:

• erasable circuit means for holding electronic key codes in address locations;
• means for identifying at least one of the address locations as a master key code address location, a master key code being a code that enables changing the contents of at least one of said address locations;
• input means for communication with a key device to receive an electronic key code from said key device;
• and
• comparison means for comparing the received electronic key code with the contents of said address locations and in response thereto performing predetermined lock-management functions;
• and wherein at a particular time:
• said input means are not in communication with any such key device;
• said comparison and function-performing means are not active;
• and
• every master key code address location is substantially empty and available for any key code from any key device that is subsequently in communication with the input means.

A self-contained electronic lock comprising:

• erasable circuit means for holding electronic key codes in address locations;
• means for identifying a particular address location, of said address locations, as a master key code address for a master key code;
• said master key code being a code that enables changing the contents of at least one of said address locations;
• input means for communication with a key device to receive an electronic key code from said key device;
• and
• means responsive to the received electronic key code for erasing the contents of the master key code address location, on the authority of the received key code if said received key code is in the master key code address location, without resort to higher authority.