A fire-blocking door lock structure includes a latching member mounted on a fire-blocking door lock and an actuation mechanism mounted in the latching member. The actuation mechanism includes a latch body having a stop portion; a stop piece which prevents retraction of the latch body and is connected...http://www.google.com/patents/US7070210?utm_source=gb-gplus-sharePatent US7070210 - Fire-blocking door lock structure
