Electronic lock reset system and method

In a lockable unit having a lock system comprising an electronic lock having a pushbutton located within the unit and accessible only when the lock is open, a nonvolatile memory containing a permanent reset code, and having addresses for user programmed master code and access codes, key each having a single permanent key code, and circuit means for reading key codes of the keys and for comparing key codes with the lock codes;

• a method of operating and resetting the lock comprising the steps of:
• programming a master code into memory by operating the pushbutton, presenting a first key to the lock, and storing the key code of the first key at the master code address to establish the first key as a master key;
• reprogramming a master code into memory by operating the pushbutton, presenting the first key to the lock, then presenting a second key to the lock, erasing the code at the master code address, and writing the key code of the second key at the master code address to establish the second as said master key;
• programming an access code into memory by first presenting said master key to the lock and within a short time period presenting a third key to the lock, and writing the key code of the third key to the access code address;
• encoding a reset key by programming the reset code into said reset key;
• presenting a key to the lock and comparing its key code to the reset, access and master codes and opening the lock if a code match is made;
• resetting the lock when the unit is locked and the pushbutton is not accessible if the key code of the presented key matches the reset code in the memory, then determining the key is the reset key erasing the code from the master code address, and removing the reset code from the reset key.

An electronically controlled lock system for a lockable unit comprising:

• a lock including a microcomputer based circuit having a nonvolatile memory containing a permanent reset code and having addresses for a master code and at least one access code;
• a plurality of keys containing permanent key codes including a master key and at least one access key;
• the circuit includes means for reading the keys and recording key codes for the master and access codes in memory, and for subsequently reading the keys and comparing the respective key codes to codes recorded in memory;
• means for opening the lock when an access key is presented to the lock and its key code matches a stored access code;
• and
• means for providing a one-time use reset key with the reset code;
• and
• means for opening the lock, erasing the access and master codes from the memory, and changing the key code in the reset key when the reset key is presented to the lock and its key code matches the stored reset code.