Patent ID: 7743523

Claim:
A device for determining the thickness or a variation in the thickness of a flat object, in particular a banknote, having at least a first and a plurality of second guide elements between which the flat object can be conveyed, whereby the second guide elements are located opposite the first guide element and whereby the second guide elements are arranged next to one another in a row so that a variation in the thickness of the flat object that is passing between the guide elements causes a deflection in one direction of one or more of the second guide elements from the first guide element, a plurality of flat coils, the flat coils being immovable, whereby each flat coil is assigned to a second guide element, and a means for energizing the flat coils for generating a magnetic alternating field, a plurality of electrically conductive elements, wherein each second guide element is either indirectly or directly rigidly attached to an electrically conductive element and a deflection of a second guide element causes a deflection of the associated electrically conductive element, an electronic evaluation circuit to detect the influence of the electrically conductive element upon the magnetic alternating field of the flat coil, whereby the flat coil is in the form of an air core coil.