1. Field of the Invention
This invention relates to the field of door lock arrangements, and in particular to a deadbolt which automatically extends into the door casing when the door is closed.
2. Brief Description of the Prior Art
Automatic deadbolt arrangements are known in the art. For example, U.S. Pat. No. 4,765,663 to Raymond et al. discloses a spring-loaded deadbolt which is automatically extended when the door into which the assembly is fitted is closed. The Raymond et al. lock assembly contains a spring-loaded deadbolt and spring-loaded plunger intercoupled to one another. The assembly is arranged such that, when the door is closed, the plunger is pushed in by the striker plate on the door frame, and this releases the spring-biased deadbolt and causes the deadbolt to be fully extended into the cavity in the striker plate. When that occurs, the linkage coupling the assembly to the door knob moves to a position in which one of its members serves as a stop to prevent the deadbolt from being forced back to a retracted position until the door knob is turned.
Another deadbolt locking device is disclosed in U.S. Pat. No. 4,262,504 to Inoue. This prior art reference discloses a locking device for locking a door and is suitable for use in an electric locking system. The device has a deadbolt which is held in a retracted position within a housing, and an actuating member adapted to be partially projected out of the housing, when the door is open. The actuating member is interrelated with the deadbolt such that the latter is driven into a hole in the door jam as the slidable member is depressed by the door in the course of closing the door. An electromagnetic plunger is provided for allowing the retraction of the deadbolt, and a manually operative member is associated with the electromagnetic plunger to allow a manual unlocking if necessary.
Other patents relating to the field of automatic locking devices are known, but are less pertinent than those described above. Among such additional prior art patents are: U.S. Pat. Nos. 600,584 to J. Kaye; U.S. Pat. No. 970,628 to A. Leistler; U.S. Pat. No. 2,854,270 to W. Ward; U.S. Pat. No. 3,891,255 to Millett; British Patent Specification No. 376,968 by Sleigh et al.; Australian Patent Specification No. 135,726 by Zeehuisen; German Patentschrift No. 75175; and German Patentschrift No. 541556.
While the aforementioned prior art teachings address the need for deadbolt lock security and disclose ways in which the deadbolt may be automatically extended when the door into which it is installed is closed, such prior art devices are limited in function and supply only those basic needs. In most prior art deadbolt door lock arrangements, the door knob, or handle, or lever of the trim (hereinafter "handle" for simplicity) will release the deadbolt and retract it, or allow it to be retracted, by turning the handle in one direction only. There is a need for a deadbolt door lock arrangement in which the deadbolt may be retracted by rotating the lever in either of the two rotational directions. This is important for being able to mount the trim to either side of a door, and would be especially important if a handle lever is used instead of a door knob, i.e., the handle must be able to be rotated in either direction for retraction of the deadbolt independent of whether it is mounted on the left side or right side of a door.
Most prior art automatic deadbolt lock arrangements have only two positions for the deadbolt, i.e. fully retracted or fully extended. In the event of an inadvertent triggering to release the deadbolt when the door is open, one must rotate the handle to effect the deadbolt retraction. It would be convenient for a deadbolt lock arrangement to have the ability for resetting the deadbolt, when inadvertently released, by pushing the deadbolt back into the fixture, applying pressure, as with the thumb, against the deadbolt itself.
There is also a need in the art for a more reliable device for ensuring the deadbolt may not be caused to retract by tampering when the door is closed.