Backlight unit and liquid crystal display device using the same

A liquid crystal display device, comprising:

• a backlight unit including a light source;
• a reflective sheet disposed at a rear surface of the light source;
• an optical sheet to direct light emitted from the light source towards a liquid crystal display panel;
• and a cover bottom assembly formed to house the light source, the reflection sheet, and the optical sheet, wherein the cover bottom assembly comprise support side bottoms formed at two short sides of the cover bottom assembly to dispose the optical sheet thereon, and the support side bottom includes a joining part to hold the optical sheet to the support side bottom using a movable body movable horizontally on the optical sheet;
• a liquid crystal display panel including an upper substrate having a color filter, a common electrode and a black matrix are formed thereon, a lower substrate on which data lines are formed to cross gate lines and a thin film transistor is formed at crossings of the data line and the gate line, and a liquid crystal formed in a space between the bonded upper and lower substrates;
• and
• a guide panel supporting the liquid crystal display panel to be joined with the support side bottom of the backlight unit,
• wherein the joining part includes two first projected parts projected from the support side bottom, the projected parts arranged to face each other and a second projected part connected between the ends of the two first projected parts.