TRANSFORMER

PROBLEM TO BE SOLVED: To provide a compact transformer capable of ensuring insulation between the primary wiring and the secondary wiring. SOLUTION: The transformer 10 includes a first winding bobbin 13; a second winding bobbin 14 and a circular magnetic core 15, wherein a plurality of protrusions 13c intersecting with the winding axis direction of a winding are formed on outer surfaces of the first winding bobbin 13, extending from end sides of a cylindrical portion; and the second winding bobbin 14 has an area, on which the other winding (the secondary winding) is wound and has a cover 16 covering an surface of the area at the side facing to the first winding bobbin. Thus, the creeping distance between a terminal, to which one winding (the primary winding) and an end of the primary winding are connected and an exposed portion of the circular magnetic core is sufficiently ensured, and the spatial distance between the terminal, to which the primary winding and the end of the primary winding are connected and a terminal to which the secondary winding and the end of the secondary winding are connected, is fully ensured. COPYRIGHT: (C)2010,JPO&INPIT