Patent ID: 7167068

Claim:
A transformer comprising: a bar-shaped ferrite core; an inner winding placed directly around said ferrite core, said inner winding being an electrically insulated flat wire having a rectangular cross section and being wounded intimately around said ferrite core with a length of the rectangular cross section extending perpendicular to an axis of said ferrite core; an outer winding wound over said inner winding; a dielectric shield made of a molding material, said dielectric shield being molded over said outer winding, said inner winding, and said ferrite core for sealing the same inside of said shield; a pair of output terminals connected across said inner winding and exposed on said dielectric shield; and a pair of input terminals connected across said outer winding and exposed on said dielectric shield; wherein said outer winding has its circumference covered by a dielectric sheath, wherein said outer winding has an intermediate winding portion between its winding start end and its winding stop end, said dielectric sheath in said intermediate winding portion being spaced from each other along the axis of said ferrite core to leave a gap thereat, said gap being filled with said molding material, wherein one turn of said outer winding is spaced along the axis of said ferrite core from the adjacent turns of said outer winding by a distance 10 μm or more within said intermediate winding portion, wherein each of said winding start end and said winding stop end includes one to two close turns of said outer winding, wherein said dielectric sheath of the outer winding is made of a self-adhesive resin.