Patent ID: 8592735

Claim:
An induction heating apparatus for heating a metal plate, comprising: an induction coil surrounding the metal plate; a first conductor, which is a part of the induction coil, placed on a front surface side of the metal plate; a second conductor, which is a part of the induction coil, placed on a back surface side of the metal plate and connected to the first conductor; and a magnetic core arranged from the front surface side over to the back surface side of the metal plate bestriding an edge portion of the metal plate; wherein vertically projected images of the first and second conductors on the metal plate do not overlap each other in a lengthwise direction of the metal plate in a central portion of the metal plate in a widthwise direction thereof; at least one of the first and second conductors is arranged so as to be slanted relative to the widthwise direction of the metal plate, or the first and second conductors are so arranged as to be at least partly overlapped in the vertically projected images in the lengthwise direction of the metal plate at least at either edge portion of the metal plate in the widthwise direction thereof; and the magnetic core is arranged in an area except a space surrounded by the induction coil so as to produce flows of magnetic flux through the metal plate from the front or back surface to the opposite surface, which flows cancel minor loops of a current formed together with a passage of an induced current corresponding to a shape of arrangement of the first and second conductors, and induced at an outer side of the first and second conductors.