Patent ID: 7145784

Claim:
A DC power source apparatus comprising: a switching element being connected to a primary winding of a transformer and configured to carry out ON/OFF operations to convert a DC voltage provided by a DC power source into high-frequency power; a rectifying/smoothing circuit configured to convert the high-frequency power being transmitted from the primary winding to a secondary winding of the transformer into a DC output voltage; and a controller configured to control ON/OFF intervals of the switching element according to the DC output voltage so that a predetermined output voltage is supplied to a load, wherein: the primary winding of the transformer includes a first primary winding having a plurality of winding layers and a second primary winding having a plurality of winding layers; the first primary winding is arranged on an inner side of the secondary winding; the second primary winding is arranged on an outer side of the secondary winding; and a terminal of a winding layer being farthest from the secondary winding among the winding layers of each of the first and second primary windings is connected to the switching element.