Patent ID: 7253714

Claim:
A transformer with high efficiency, said transformer comprises: an iron core being a closed annular member made by continuous winding from a silicon steel sheet, and then being completed by being sintered and fixed to keep its directionality; after first time insulation processing with a heat shrinking wrapper on said iron core, a first insulation layer being formed; a primary coil being formed by winding a wire in annular shapes on said first insulation layer, then by being enveloped by a second insulation layer formed by second time insulation processing with a heat shrinking wrapper; and a secondary coil being formed by winding a wire in annular shapes on said second insulation layer, and then by being enveloped by a third insulation layer formed by third time insulation processing with a heat shrinking wrapper; said third insulation layer having a pair of end input wires of said primary coil as well as a pair of end output wires of said secondary coil extended outwards; said input wires of said primary coil input electric power, and said output wires of said secondary coil output voltage-changed electric power, thereby an annular transformer being formed.