Patent ID: 7804388

Claim:
A transformer, comprising: a coil frame comprising a plurality of partitions, a plurality of first coil grooves and a plurality of coil openings, in which the partitions define the first coil grooves, and the coil openings are formed on the partitions and connect the first coil grooves; an input coil disposed on the coil frame, passing the coil openings and wound in the first coil grooves; and an output coil disposed on the coil frame and interlaced with the input coil, in which the output coil comprises at least one metallic strip, and a second voltage outputted by the output coil is induced by a first voltage inputted into the input coil, wherein the coil opening of each of the partitions is defined by two side walls, at least one of the side walls is a tapered wall having a chamfered angle or a rounded wall having a rounded angle, and a bended angle formed by the input coil at the location where the input coil passes each of the coil openings is substantially less than 15 degrees.