Optical sheet module and backlight unit having same

A backlight unit comprising:

• a light source transferring light upwardly;
• a lamp reflection plate converting the light generated by the light source into planar light;
• a base film having a sheet shape and transmitting the planar light converted by the lamp reflection plate;
• and
• a light collector part disposed on a lower portion of the base film and comprising light collector units each having a light entrance surface configured to transmit light emitted by the light source and allow the light to enter the light collector units and a light refracting surface configured to be disposed opposite to the light entrance surface and reflect the light incident through the light entrance surface to transfer the reflected light upwardly, wherein the light collector units each have a cross section gradually decreasing toward a lower portion thereof and are continuously and repeatedly arranged in a direction in which the light is emitted by the light source,
• wherein a vertical cross-sectional trajectory of the light refracting surface of the light collector part is inwardly indented with respect to a virtual straight line trajectory extending in a top-bottom direction,
• wherein the light refracting surface has a first inclined surface having a lower tip contacting the light entrance surface and upwardly inclined at a first angle, and a second inclined surface extending upwardly from the first inclined surface and upwardly inclined at a second angle narrower than the first angle, and a cross-sectional trajectory along a vertical direction is formed to be recessed in an inner direction with respect to an imaginary linear trajectory,
• wherein portions of the light incident through the light entrance surface are reflected in different directions by the first inclined surface and the second inclined surface,
• wherein the light refracting surface has a length (lb) in a transverse direction with respect to a direction in which light is emitted from the light source is formed to be longer than a length (la) in the transverse direction of the light entrance surface,
• wherein a length along the transverse direction of the second inclined surface is adjusted by a third length along the transverse direction of the first inclined surface,
• wherein the second angle is an inclination angle of the first inclined surface, and the third angle is an inclined angle of the second inclined surface, and
• wherein the second angle and the third angle are adjusted according to a length (lc) along the transverse direction of the first inclined surface.