US Patent 7218199 Structure of transformer

A transformer includes a primary winding coil, a plurality of electrically-conductive sheets, a bobbin and a magnetic core assembly. The bobbin includes a first tube member, a second tube member and plural partition plates. The first tube member and the second tube member have a first channel and a second channel therein, respectively. Each partition plate is sheathed around the first tube member and the second tube member and includes a receptacle for accommodating respective electrically-conductive sheet, and the primary winding coil is wound around the second tube member.