Exit door security system

Abstract

The system automatically warns when opening of an exit door is attempted, causing an alarm to be made and preventing full opening for a predetermined period of time. Such a system includes an electromagnet, timer, alarm and activator switch connected in series with a power source such as house current and disposed in and around the frame with no electrical connection to or from the door. A magnetically attractable plate or prong is secured to the door adjacent to the electromagnet. The switch may include a spring biased plunger on the frame, held in the closed circuit position against the spring bias with the door closed. The switch automatically moves to the closed circuit position when the door begins to open, causing an alarm to be immediately sounded and the plate to continue to be strongly held by the electromagnet, thereby preventing full opening of the door. The system permits the full opening of the exit door only after a suitable period of time has elapsed.

Dependencies are inferred from the claim text.