A picture frame or a doorbell having warning function includes a main body consisting of a front housing, a rear housing and a transparent plate for placing photos or pictures. The main body is provided with a sensor hole, a speaker, an electronic control circuit and/or an emission circuit to deliver...http://www.google.com/patents/US6653931?utm_source=gb-gplus-sharePatent US6653931 - Picture frame or doorbell having warning function
