| 摘要 |
The present invention relates to a backlight unit capable of providing high color reproduction by using a fluorescent material. The backlight unit includes: a blue light source for emitting blue light; a light guide plate for outputting the blue light incident from the blue light source through an emitting surface; and an optical sheet adjacent to the emitting surface of the light guide plate. The optical sheet includes: a lower layer onto which blue light is incident; a middle layer including a fluorescent material for changing color of the blue light; and an upper layer for outputting the light changed by the fluorescent material, wherein the lower, middle, and upper layers of the optical sheet include siloxane and phenyl, and refractive indexes of the lower, middle, and upper layers are determined based on a phenyl content. The refractive index of the middle layer of the optical sheet is larger than the refractive index of the lower layer of the optical sheet, and the refractive index of the upper layer of the optical sheet is larger than or equal to the refractive index of the middle layer of the optical sheet. The refractive index of the lower layer of the optical sheet is 1.0 to 1.5, the refractive index of the middle layer of the optical sheet is 2.0 to 2.5, and the refractive index of the upper layer of the optical sheet is 2.0 to 2.5. |
