Patent ID: 6864419
Filing Date: 2005-03-08
Classification: H05B,H05K

Abstract:
1. An electromagnetic shield for shielding a magnetic field produced around a one or more coils having ac current flowing in the one or more coils, through which a workpiece moves for induction heating of the workpiece by the magnetic field, the electromagnetic shield comprising: a first transverse screen element and a second transverse screen element through which the workpiece moves, the first and second transverse screen elements disposed at opposing ends of the one or more coils, each of the first and second transverse screen elements having a discontinuity, a first longitudinal screen section connecting a first end of the first transverse screen element at the discontinuity in the first transverse screen element to a first end of the second transverse screen element at the discontinuity in the second transverse screen element, the first longitudinal screen section disposed laterally to an edge of the workpiece; and a second longitudinal screen section connecting a second end of the first transverse screen element at the discontinuity in the first transverse screen element to a second end of the second transverse screen element at the discontinuity in the second transverse screen element, the second longitudinal screen section disposed laterally to the edge of the workpiece and adjacent to the first longitudinal screen section, whereby current induced in the electromagnetic shield by the, magnetic field flows in the closed circuit path established by the first transverse screen element, the first longitudinal screen section, the second transverse screen element and the second longitudinal screen section, and opposing electromagnetic fields established by opposing currents in the first and second longitudinal screen sections substantially cancel each other.