Backlight unit and liquid crystal display device including the same

A backlight unit for a liquid crystal display panel, comprising:

• a diffusor that diffuses light emitted from a front surface thereof;
• and
• a collimator that collimates the light emitted from the front surface of the diffusor toward the liquid crystal display panel, the collimator including:
• a base layer that refracts the diffused light from the diffusor toward the liquid crystal panel, the base layer has a single flat rear surface such that a rear of the entire base layer is evenly formed,
• a collimating layer of lenses on a front surface of the base layer, each of the lenses refracts the light refracted from a first region of the base layer toward the liquid crystal panel and reflects the light refracted from a second region of the base layer to the single flat rear surface of the base layer, and
• a reflective pattern contacting and directly on the single flat rear surface of the base layer along a boundary of each of the lenses, the reflective pattern in a matrix shape having a plurality of apertures each facing each of the lenses, a ratio of an area of the aperture portion of the each of the lenses to an area of the base layer facing the corresponding one of the lenses is in a range of about 30% to about 70%, wherein the single flat rear surface of the base layer includes first, second and third regions, and
• wherein when the diffused light is incident on the single flat rear surface of the base layer with an incident angle of about 5°, the light entering the first region is collimated toward the liquid crystal panel to have an azimuthal angle within a range of about 0° to about 30° in a front direction, the light entering the second region is totally reflected at a front surface of the collimating layer and toward the single flat rear surface of the base layer and is recycled, and the light entering the third region is reflected at the reflective pattern and toward the diffuser and is recycled.