Optical film and backlight unit including the same

A backlight unit comprising:

• a light source;
• a color conversion sheet disposed on the light source;
• a first optical film disposed on the color conversion sheet, the first optical film comprising:
• a first sheet including a first base portion;
• a first pattern layer including a plurality of first prisms wherein each first prism has a first vertex angle and a first height, the first prisms are arranged parallel along a first direction with a first pitch distance between the first prisms and are formed on a first surface of the first base portion;
• and a second pattern layer including a plurality of first intaglio pyramids wherein each first intaglio pyramid has a second vertex angle and a second height, the first intaglio pyramids are arranged parallel along a second direction as a row direction of the first intaglio pyramids and a third direction as a column direction of the first intaglio pyramids with a second pitch distance between the first intaglio pyramids, and are formed as intaglio on a second surface of the first base portion;
• and
• a second sheet including a second base portion;
• a third pattern layer where a plurality of protrusions with an adhesive property is arranged randomly and is formed as a matte pattern on a third surface of the second base portion;
• and a fourth pattern layer including a plurality of second intaglio pyramids arranged parallel along a fourth direction as a row direction of the second intaglio pyramids and a fifth direction as a column direction of the second intaglio pyramids and formed as intaglio on a fourth surface of the second base portion,
• wherein the first direction and the second direction form an angle in a range of 40° to 50°, the second direction and the fourth direction are substantially the same direction, the third direction and the fifth direction are substantially the same direction, and the first sheet and the second sheet are laminated through the third pattern layer;
• a second optical film disposed on the first optical film, the second optical film comprising:
• a third sheet including a third base portion, and a fifth pattern layer including a plurality of second prisms where the second prisms are arranged parallel along a sixth direction and are formed on a fifth surface of the third base portion;
• and
• a fourth sheet including a fourth base portion, and a sixth pattern layer including a plurality of third prisms where the third prisms are arranged parallel along a seventh direction and are formed on a sixth surface of the fourth base portion,
• wherein the fourth sheet is disposed on the first sheet of the first optical film, the third sheet is disposed on the fourth sheet, and the sixth direction and the seventh direction form an angle in a range of 85° to 95°;
• and
• a diffusion sheet disposed on the third sheet of the second optical film.