Patent ID: 7095308

Claim:
A step-up transformer comprising: a primary winding supplied with a switching voltage that switches at a predetermined frequency; a plurality of secondary windings for stepping up said switching voltage supplied to said primary winding, wherein said secondary windings are laminated in a plurality of layers, are divided based on a predetermined number of turns, and respectively are opened at first ends thereof; a bobbin for providing a predetermined spacing between said plurality of secondary windings and said primary winding and including a plurality of terminals for respectively winding second ends of said plurality of secondary windings therearound; a core inserted in said bobbin, excited by said switching voltage supplied to said primary winding, and forming a closed magnetic circuit; a plurality of insulating films wound around said bobbin so as to space said plurality of secondary windings from each other by respective predetermined thicknesses; rectifying portions provided at the second ends of said plurality of secondary windings for rectifying stepped-up voltages obtained at the second ends of said secondary windings; and a cut out film projection portion formed on each of said plurality of insulating films wherein said portion includes a substantially rectilinear shape around which the first ends of said secondary windings are wound.