| 摘要 |
PURPOSE: A brightness increasing film and a backlight unit including the same are provided to improve side viewing angle characteristics by having uniform brightness distribution. CONSTITUTION: A multi-layered thin film(3) comprises a first thin film and a second thin film. The difference of a refractive index of the first thin film and the second thin film is less than or equal to 0.03. The first thin film comprises a resin in which the content of ethylene naphthalate recurring unit is greater or equal to 80 mole%. The second thin film comprises a resin the content of the ethylene naphthalate recurring unit is 10-60mol% inclusive. The second thin film is closely arranged with the first thin film. A brightness increasing film comprises a first shaft and a second shaft. The brightness increasing film reflects light polarized along the first shaft and transmits light polarized along the second shaft. |
