| 摘要 |
An automatic door latch is disclosed. In a preferred embodiment, the latch includes a dead bolt which is automatically moved from a partially retracted or trigger position to a fully extended locking position when a door in which the lock is mounted is closed. When a key is used to unlock the dead bolt from outside of the door, or a finger turn or key is used to unlock the dead bolt from inside of the door, the dead bolt is automatically reset to the trigger position. In a preferred embodiment, the dead bolt lock includes a multi-position switch mounted in the lock housing which engages a contact member mounted on the dead bolt. Retraction of the dead bolt into the housing causes the multi-position switch to engage the contact member and to secure the dead bolt in the trigger position. Subsequent retraction of the dead bolt into the housing causes the multi-position switch to disengage from the contact member, thereby allowing the dead bolt to extend from the housing to the locked position. In a preferred embodiment, a latch restraint assembly is provided which holds the dead bolt in the fully retracted position until the restraint assembly is manually released. The automatic door latch comprises relatively few component parts in comparison with conventional locks, and is preferably compatible with standard predrilled door cut-outs.< /SDOAB>
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