| 摘要 |
A door lock for preventing unauthorized ingress and solely actuable from the inside of a room. The lock includes a lock bar, pivotally anchored to the outer edge of the door, and a jamb plate, anchored to the adjacent jamb and having an elongated vertical aperture for door locking engagement by the lock bar free end portion when the door is closed. A stem is slidably mounted on the lock bar to take a blocking position protruding beyond the free end portion of the lock bar for releasably extending through the jamb plate aperture. When the stem is engaged into the jamb plate aperture, the lock bar is prevented from pivoting because the stem has no clearance to do so within the aperture. Thus, a person outside the room could not release the lock bar by upward pivotal thereof, for instance by inserting a blade through the vertical air gap between the door outer edge and the jamb plate, underneath the lock bar, and then lifting same.
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