A document detecting arrangement

Claim 1

An arrangement for detecting documents, such as bank notes, cheques, coupons and the like, exhibiting magnetic properties, the arrangement including transport means (11) for transporting documents along a transport path (0-0) past a magnetic detector (12-14) the magnetic detector (12-14) including means (12) for generating a permanent magnetic field in a magnetic circuit (13) and being so positioned in relation to the transport means (12) that transported documents are caused to pass the circuit (13) and therewith cause changes to occur in the magnetic field in response to the magnetic properties of the documents, characterized in that the magnetic circuit (13) includes a narrow air gap (131) located adjacent the transport path (0-0), a plane passing through the air gap intercepting the transport path (0-0) essentially perpendicularly to said path, and further includes a detector means (14) which is intended to detect any change in the magnetic field that might occur; in that the north-south-direction of the magnetic field generating means (12) located adjacent the air gap extends in the same direction as an intersecting line between said plane and a passing docu­ment, the permanent magnetic field located closely adja­cent the air gap (131) being directed in a plane through the air gap at right angles to the direction of the trans­port path (0-0) adjacent the air gap (131); and in that the output side of the detector means (14) is connected to a signal processing means (30-34) for generating a signal in dependence on the magnetic properties of the document.