Reprogrammable lock and keys therefor

A reprogrammable lock assembly comprising:

• a housing having at least one longitudinal pocket formed in the inner surface thereof;
• a carrier plug rotatably mounted within said housing and having a plurality of radially extending slots spaced from one another along the longitudinal axis of said plug, said plug including a longitudinal opening adapted to receive a key;
• a plurality of tumbler members respectively mounted in said slots of said plug and slidable therein for extension into said at least one longitudinal pocket of said housing to prevent rotation of said plug within said housing maintaining the lock assembly in a locked position, said tumbler members having first and second serrated edges;
• a corresponding plurality of key-follower members having a serrated edge respectively mounted in said slots of said plug in adjustable edge engagement with corresponding tumbler members in a variable code pattern so that the insertion of a key with a code pattern matching the selected code pattern of said key-followers causes said key-followers to retract all said tumblers from at least one longitudinal pocket of said housing;
• a retainer bar mounted on said carrier plug and interposed in said housing to hold said tumbler members and said key-followers in serrated edge engagement during normal operation of the lock and to allow disengagement of said key-follower members and said tumbler members when said plug is rotated to a program position within said housing, said retainer bar moving into said a least one longitudinal pocket to allow separation of said key-follower members and said tumbler members when said plug is rotated to the program position;
• a latch controlling driver assembly received within the inner end of said housing and matingly engaging said carrier plug, said driver assembly axially displaceable within said housing by at least one key between a locked position preventing rotation of said carrier plug, a program position allowing rotation of said carrier plug in a first direction from an initial reference position, and an unlock position allowing rotation of said carrier plug in a second direction from said reference position to unlatch said lock assembly, said driver assembly including a driver matingly received within said carrier plug, a latch-controlling tailpiece and an adapter to key said driver to said tailpiece, said driver assembly biased towards said locked position;
• and
• at least one stop member disposed within said housing to selectively prevent rotation of said driver assembly.

A method of reprogramming a lock assembly for unlatching using a second use key having a code pattern different from a first use key comprising the steps of:

• inserting a first program key having a code pattern identical to the code pattern of the first use key into a key slot of the lock assembly;
• rotating the first program key in a first direction relative to an initial reference position thereby rotating the carrier plug of the lock assembly in said first direction;
• removing the first program key from the key slot;
• inserting a second program key having a code pattern identical to the code pattern of the second use key into the key slot of the lock assembly;
• rotating the second program key in a second direction back to the initial reference position thereby resetting the tumbler members and key-follower members of the lock assembly to match the code pattern of the second use key;
• and
• removing the second program key from the key slot whereby the second use key can be utilized to rotate the carrier plug in the second direction from the initial reference position to unlatch the lock assembly.

A set of keys for a programmable lock assembly comprising:

• a plurality of program keys, each of said program keys having a different code pattern;
• and
• a corresponding plurality of use keys, each of said use keys having a different code pattern corresponding to the code pattern of said program keys;
• wherein said use keys have a length greater than the length of said program keys such that said use keys can be utilized only to move the lock assembly between a reference position and an unlock position and said program keys can be utilized only to move the lock assembly between said reference position and a program position, said program keys and use keys capable of receiving a code pattern having three different depths.