Optical film having inclined films, and backlight unit and display device using the same

A backlight unit, comprising:

• a light source;
• a light guide plate facing the light source and configured to change a path of light emitted from the light source;
• a reflective plate below the light guide plate;
• and
• an optical film above the light guide plate, the optical film comprising:
• a plurality of base layers arranged at predetermined intervals in a horizontal direction;
• and
• a plurality of barriers respectively provided between pairs of the plurality of base layers,
• wherein each of the plurality of barriers comprises first and second films inclined with a first inclined angle with respect to a lower surface of each of the plurality of base layers,
• wherein the plurality of barriers include a first barrier and a second barrier facing each other by interposing any one of the plurality of base layers therebetween, and the second film of the first barrier faces the first film of the second barrier with the one of the plurality of base layers interposed therebetween,
• wherein the first film of the first barrier is configured to:
• transmit light polarized in a first direction, and
• reflect light polarized in a second direction perpendicular to the first direction so as to emit the reflected light through an upper surface of an optical sheet, and
• wherein the second film of the first barrier is configured to phase-retard the light polarized in the first direction to the light polarized in the second direction to allow the light phase-retarded to enter the first film of the second barrier, and
• wherein the first film of the second barrier is provided to reflect the light phase-retarded in the second film of the first barrier so as to emit the reflected light through an upper surface of the optical sheet.

A display device, comprising:

• a backlight unit;
• and
• a display panel above the backlight unit,
• wherein the backlight unit comprises an optical film provided below the display panel, and
• wherein the optical film comprises:
• a plurality of base layers arranged at predetermined intervals in a horizontal direction, and
• a plurality of barriers respectively provided between pairs of the plurality of base layers,
• wherein each of the plurality of barriers comprises first and second films inclined with a first inclined angle with respect to a lower surface of each of the plurality of base layers,
• wherein the plurality of barriers include a first barrier and a second barrier facing each other by interposing any one of the plurality of base layers therebetween, and the second film of the first barrier faces the first film of the second barrier with the one of the plurality of base layers interposed therebetween,
• wherein the first film of the first barrier is configured to:
• transmit light polarized in a first direction, and
• reflect light polarized in a second direction perpendicular to the first direction so as to emit the reflected light through an upper surface of an optical sheet, and
• wherein the second film of the first barrier is configured to phase-retard the light polarized in the first direction to the light polarized in the second direction to allow the light phase-retarded to enter the first film of the second barrier, and
• wherein the first film of the second barrier is provided to reflect the light phase-retarded in the second film of the first barrier so as to emit the reflected light through an upper surface of the optical sheet.