Prism sheet and backlight unit using the same

A backlight unit comprising:

• a lamp that emits light;
• a light guide plate that receives the light emitted from the light, and changes a path direction of the light to a direction substantially perpendicular to an upper surface of the light guide plate;
• and
• a prism sheet that condenses the light emerging from the light guide plate,
• wherein the prism sheet includes:
• a condensing film that transmits the light emerging from the light guide plate;
• a plurality of prism crests on the condensing film, each prism crest havina a pair of sloping sides that intersect to form an apex of the prism crest, and wherein facing sloping sides of adjacent ones of the prism crests define valleys between the adjacent ones of the prism crests on the condensing film;
• and
• a plurality of reflection patterns formed on the condensing film such that each of the reflection patterns faces and overlaps a valley between adjacent prism crests associated with the reflection pattern to reflect light incident onto the reflection patterns,
• wherein there is a one to one correspondence between the reflection patterns and the valleys between adjacent prism crests.

A backlight unit comprising:

• a plurality of lamps that emit light;
• a bottom cover that receives and supports the lamps;
• a diffusion plate that covers an upper surface of the bottom cover and diffuses light emitted from the lamps;
• and
• a prism sheet that condenses light emerging from the diffusion plate,
• wherein the prism sheet includes:
• a condensing film that transmits the light emerging from the light guide plate;
• a plurality of prism crests on the condensing film, each prism crest having a pair of sloping sides that intersect to form an apex of the prism crest, and wherein facing sloping sides of adjacent ones of the prism crests define valleys between the adjacent ones of the prism crests on the condensing film;
• and
• a plurality of reflection patterns formed on the condensing film such that each of the reflection patterns faces and overlaps a valley between adjacent prism crests associated with the reflection pattern to reflect light incident onto the reflection patterns,
• wherein there is a one to one correspondence between the reflection patterns and the valleys between adjacent prism crests.

A prism sheet comprising:

• a condensing film that transmits light incident to the condensing film;
• a plurality of prism crests on the condensing film, each prism crest having a pair of sloping sides that intersect to form an apex of the prism crest, and wherein facing sloping sides of adjacent ones of the prism crests define valleys between the adjacent ones of the prism crests on the condensing film;
• and
• a plurality of reflection patterns formed on the condensing film such that each of the reflection patterns is aligned with and overlaps each valley defined between adjacent prism crests associated with the reflection pattern to reflect light incident onto the reflection patterns,
• wherein there is a one to one correspondence between the reflection patterns and the valleys between adjacent prism crests.