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AssigneeDe La Rue International Limited
InventorsJohn Buttifant, John Skinner, Peter Evans, Michael Potter, Peter Pullan, Barry Scowen
Estimating the term…
A method of detecting a magnetic thread comprises causing relative movement between the thread and an array of magnetic heads, each head generates a signal upon detecting a portion of the thread. The arrival of a thread at one of the heads is detected, that head being denoted a primary head, and the head on each side a secondary head. Output signals from the primary and secondary heads are monitored to generate a representation of the thread, and the magnitude of the signals from the primary and secondary heads are compared such that if the magnitude of the output signal from a secondary head exceeds that from the primary head, the primary and secondary heads are reallocated accordingly.
A method of detecting a coded magnetic thread comprising sensing the response of a magnetic field detector as a thread passes the detector, the response varying from an initial magnitude in first and second senses to exhibit a first peak, and then in the first sense to exhibit a second peak;
Apparatus for detecting a coded magnetic thread comprising a magnetic field detector, a processing system for monitoring the response of the detector as a thread passes the detector, the response varying from an initial magnitude in first and second senses to exhibit a first peak, and then in the first sense to exhibit a second peak, wherein the processing system is configured to compare the response of the detector against a first threshold disposed about the initial magnitude in the first sense, measure the first peak of the response of the detector, and to adjust the first threshold in accordance with a predetermined algorithm based on the magnitude of the first peak.
Dependencies are inferred from the claim text.