LOCK

摘要

The present invention provides a lock having a bolt (7), fitted to a door (1) that can move between a closed position and an open position. When the door is in the closed position, the lock bolt projects into a recess in the door frame (10) to lock the door. The bolt (7) can be moved into a retracted position by a key- or a knob- operated lock cylinder (57) to unlock the door. The lock has a holdback (30) for holding the bolt in its unlocked position after the key has been removed, thereby allowing the door to be opened without the user having to keep it open. The lock also has a lock actuator (6, 20) that releases the bolt from the holdback as the door is closed and the bolt is then projected by a spring (51) into the recess to lock the closed door. The lock actuator includes a trigger bar (6) that is separate from the bolt (7) to release the bolt from its retracted position when the door is closed. Such a trigger bar (6) is biased by a spring (12) so that it projects out of the lock when the door is opened but is forced back into the lock by the surrounding door frame (8) when the door is closed. It is the latter action that releases the bolt (7) from its retracted position and it is held in its retracted position from the time that it is withdrawn by the lock. The trigger bar (6) is connected to a central operating mechanism (20) which is connected to the bolt (7) via a spring (51) such that when the trigger bar (6) is retracted as when it meets the strike plate (9) the bolt (7) is forced forwards via the spring (51). The springs (12 and 51) are arranged together with the central operating mechanism (20) such that when a backwards force is removed from trigger bar (6) it projects forwards thus retracting the bolt (7) backwards.