In the prior art, various types of electronic door locks have been proposed. One type involves an electronic strike which is mounted in the frame of a door. In this type of lock, the strike is operated electronically to catch or release the door latch of the door for locking or unlocking purposes.
U.S. Pat. No. 5,100,184 to Schmitt discloses another type of lock or deadlatch assembly. This deadlatch assembly is designed to allow 2-way traffic, i.e. free entrance and exit at some times and exit-only traffic at other times. These deadlatch assemblies are typically used with narrow type or narrow stile door applications such as aluminum doors. This deadlatch assembly includes a solenoid actuator for moving a deadlatch cam to an unblocking position when an auxiliary bolt is retracted and the door closed. A ramp in the door strike plate and a beveled latch bolt facilitate opening of the door without the need for an electric strike.
Exemplary of a narrow stile door lock mechanism is U.S. Pat. No. 3,011,817 to Eads. These types of door locks are manufactured by Adams Rite Manufacturing Company. Other patents related to these types of door locks include U.S. Pat. Nos. 2,666,321, 2,989,859, 3,073,143, 3,175,376, 3,695,.068, 3,869,159, 3,899,906, 4,218,903, 4,637,237, 4,643,005, 4,848,118 and 5,100,184. These patents are herein incorporated by reference in their entirety for the teachings related to deadlatch assemblies and/or narrow stile door locks.
One of the disadvantages of electronic door strikes is the inability to always permit egress from an area when a power outage or lock malfunction occurs. That is, if an electronic strike is in a position where the door is locked and a power failure occurs, persons within the locked facility cannot escape. This inability to escape represents an extremely hazardous or dangerous situation in the case of a fire, toxic chemical leak or the like. Another problem relates to new codes being enacted wherein persons in the facility must always be able to escape therefrom. Electronic strikes may not be able to meet such codes for the reason described above.
The deadlatch assembly described in U.S. Pat. No. 5,100,184 to Schmitt is disadvantageous in that modifications to an off the shelf deadlatch assembly must be made before the lock can be functional.
In response to the deficiencies above, a need has developed to provide an improved electronic lock which interfaces with existing narrow stile door locks and also allows for free egress from a facility in the case of a power outage, lock malfunction or the like.
Responsive to this need, the present invention provides an electronic lock which interfaces with a conventional narrow stile door lock and which allows electronic control of the door lock while permitting egress from a locked facility if need be.