Abstract: An electronic lock is constructed to resemble the appearance and functionality of a conventional cylinder lock. Its key has a bit in which is mounted an integrated circuit chip storing the key code and including a transmission coil for inductive coupling with a reading head in the lock. The latter includes a coil for generating a high frequency alternating magnetic field across a localized region of the keyway concentrated via a toroidal ferrite core structure which defines a gap spanning the keyway through which the chip passes when the key bit is inserted. This core structure includes a U-shaped part in the stationary lock housing around which the coil is wound, and two parts mounted in the barrel, one to either side of the keyway, which register with the part in the housing when the barrel is in the key-reading position. Further ferrite pads may be mounted to either side of the coil in the key itself, to register with the ferrite parts in the barrel.

Abstract: A lock which is adapted to transduce the code from a key by electronic means is constructed to resemble the form and functionality of a conventional mechanical cylinder lock. A main casing houses the bolt, a rotatable thrower or cam for retracting the bolt, an electromechanical release mechanism which normally blocks rotation of the thrower, and a processor to control the release mechanism in response to the detected key code. The electronic reading means are located in association with the keyway of a rotatable barrel in a cylinder unit manufactured as a separate unit from the main casing. The thrower and barrel have respective cooperating mechanical couplings and the main casing and cylinder unit have respective cooperating electrical connectors. The lock is therefore assembled by attaching the cylinder unit to the outside of the main casing, thus establishing a rotary driving connection from the barrel to the thrower and establishing an electrical connection from the key reader to the processor.

Abstract: An "electronic" lock has a thrower with a radial lug for extending and retracting the bolt when turned by a key carrying a proper code. Turning of the thrower through a sufficient distance to shift the bolt is normally blocked by a dogging lever with which the thrower lug abuts. The thrower lug also sweeps a cam track on a second lever so as to pivot the latter during initial turning movement of the thrower away from its rest position. The second lever carries an electromagnet. While the electromagnet remains de-energized there is no interaction between the two levers so that the second lever can pivot independently of the first and turning of the thrower remains limited. When a correct key code is detected, however, the electromagnet is energized to hold the two levers together. Initial turning of the thrower thereby causes the second lever to carry the dogging lever away from its blocking position and thus free the thrower for 360.degree. movement.