Patent ID: 7285953

Claim:
A device for producing a detection signal when interfering components occur in an at least largely nonconductive stream of material being conveyed via a conveyor, comprising: an alternating current generator configured to build up, through a transmitting coil, an alternating electromagnetic field in a segment of the stream of material; a coil system configured to detect changes in amplitude and phase of the alternating electromagnetic field; an evaluation circuit coupled to the coil system and configured to derive the detection signal, which, when an interfering component of the material being conveyed appears, causes the conveyor to be stopped for removal of the interfering component from the stream; a resetting device capable of canceling the stoppage of the conveyor; and a blocking device controlled by the evaluation circuit and provided for the resetting device, the blocking device configured to disable the resetting device as long as the evaluating circuit is still emitting a signal that is classifiable as a detection signal.