| 摘要 |
<p>In a first embodiment, the invention has a casing set in the frame of a door in confronting relationship to the latchbolt-confining housing of the door. A bolt, translatable in the casing, is extended, by a solenoid, and enters the housing to prevent opening of the door. A latchbolt position sensor, in the form of a dual-ended limb, monitors the position of the latchbolt. Upon withdrawal of the latchbolt, from latching closure of the door, the limb actuates a switch to operate a time delay circuit component. When the specified time delay set by the component has run its course, it cuts power to the solenoid. Compression springs withdraw the bolt from the latchbolt-confining housing, to permit the door to open.</p> |
