Patent ID: 8669838

Claim:
A transformer having assembled bobbins, including: a plurality of bobbins each having an annular groove provided on its outer edge, a hollow portion, and a plurality of protrusions formed on a surface of the bobbin to surround the hollow portion, the protrusions forming a gap between the two adjacent bobbins when the two adjacent bobbins are assembled with each other; a plurality of secondary windings disposed between the bobbins, each of the secondary windings having a through-hole corresponding to the hollow portion; two magnetic cores penetrating the hollow portions of the bobbins and the through-holes of the secondary windings to assemble them together; and a base provided with a penetration hole, the hollow portion of each of the bobbins being positioned to correspond to the penetration hole, each of the magnetic cores passing through the penetration hole of the base and the hollow portions of the bobbins to assemble them together, wherein each of the bobbins has two lateral plates, the hollow portion is a through-hole, the annular groove is enclosed by the two lateral plates and outer walls of the hollow portion, and the protrusions are formed on at least one of the lateral plates.