A self-contained alarm/annunciator system for a door provides an alarm function and a flashing LED when the door is locked to deter attempted burglary, and an annunciator function operable when the door is unlocked to indicate attempted door opening....http://www.google.fr/patents/US5311168?utm_source=gb-gplus-shareBrevet US5311168 - Lock set with self-contained door alarm and annunciator system
Lock set with self-contained door alarm and annunciator system
