Backlight unit and display device using the same

A display device, comprising:

• a display panel;
• and
• a backlight unit disposed under the display panel and configured to emit light to the display panel,
• wherein the backlight unit includes:
• a plurality of light emitting elements disposed on a substrate, each of the plurality of light emitting elements having a flip chip structure;
• a reflector disposed between respective adjacent light emitting elements of the plurality of light emitting elements, the reflector having a plurality of first grooves, each of the plurality of first grooves having a predetermined size disposed on a respective upper surface of the reflector;
• and
• a transparent sheet disposed on the reflector and the plurality of light emitting elements, the transparent sheet including a plurality of optical path changing patterns, each of the plurality of optical path changing patterns disposed at a position overlapping a respective light emitting element of the plurality of light emitting elements on an opposite side of a surface of the transparent sheet adjacent to the plurality of light emitting elements, each of the plurality of optical path changing patterns having a first thickness at a central region being greater than a second thickness at an outer region.