Transformer and flat panel display device including same

A transformer comprising:

• a core unit having an upper core and a lower core;
• and
• a coil unit disposed in the core unit,
• wherein the coil unit comprises:
• a first coil wound in a first direction;
• a second coil wound in a second direction, the second direction being opposite the first direction;
• and
• a third coil having a flat plate shape,
• wherein the upper core comprises:
• a body portion;
• a first leg portion and a second leg portion protruding from the body portion;
• and
• a spacing portion formed between the first leg portion and the second leg portion,
• wherein the first leg portion comprises two first outer legs and a first center leg disposed between the two first outer legs,
• wherein the second leg portion comprises two second outer legs and a second center leg disposed between the two second outer legs,
• wherein the first coil is disposed to surround only the first center leg,
• wherein the second coil is disposed to surround only the second center leg,
• wherein the second coil is disposed on the first coil such that a portion of the second coil overlaps the first coil in a thickness direction,
• wherein the third coil is disposed to surround only the first center leg.

A transformer comprising:

• a core unit having an upper core and a lower core;
• and
• a coil unit disposed in the core unit,
• wherein the coil unit comprises:
• a first coil wound in a first direction;
• a second coil wound in a second direction, the second direction being opposite the first direction;
• and
• a third coil having a flat plate shape,
• wherein the upper core comprises:
• a body portion;
• a first leg portion and a second leg portion protruding from the body portion;
• and
• a spacing portion formed between the first leg portion and the second leg portion,
• wherein the first leg portion comprises two first outer legs and a first center leg disposed between the two first outer legs,
• wherein the second leg portion comprises two second outer legs and a second center leg disposed between the two second outer legs,
• wherein the first coil is disposed to surround only the first center leg,
• wherein the second coil is disposed to surround only the second center leg,
• wherein the second coil is disposed on the first coil such that a portion of the second coil overlaps the first coil in a thickness direction,
• wherein the first coil and the second coil have ends led out toward a first side, and
• wherein the third coil has ends led out toward a second side, the second side being opposite the first side.