Perimeter sensing device

Abstract

A perimeter monitoring device is disposed so as to detect passage of objects through a monitored space above a perimeter line and to generate a perimeter signal in correspondence with such a detected passage. The monitoring device includes at least one sensor element disposed along the perimeter line to be monitored and a processing unit coupled to the sensor element so as to detect electrical current generated in the sensor element from the movement of the intruding object past the sensor element. Each sensor element comprises a loop of electrically conductive material that is electrically isolated from the other sensor element, and each of which is separately electrically coupled to the processing unit. The perimeter detection system further comprises an electrical insulation material, such as a mat, that is disposed between the conductive sensor element and the monitored space. The signal generated by the processing unit in correspondence with the detection of an object passing through the monitored area is typically coupled to control mechanisms for the equipment, such as a radiation imager, located within the cordoned area, so that operation of the equipment can be stopped or modified to minimize the chance of the equipment causing harm to an intruder passing across the perimeter line.