A SECURITY SYSTEM

摘要

A security system provided with an active sensor comprising at least one source for emitting electromagnetic light in a room to be guarded and at least one detector for detecting electromagnetic light striking thereon, and with an alarm for generating an alarm signal in dependence on a detection signal being delivered by the at least one detector, whereby the security system comprises at least one label provided in the room to be guarded, which directs incident electromagnetic light emanating from the at least one source in modified form to the at least one detector, whereby the at least one detector delivers a detection signal in case of a typical change in the electromagnetic light striking thereon.