| 摘要 |
PURPOSE: To provide a sheet for surface illumination which suppresses the degradation in utilization efficiency of incident light and realizes the reduced thickness of a light transmission body and a surface illumination device and liquid crystal display device formed by using the same sheet. CONSTITUTION: The liquid crystal display device 20 is mainly composed of a back light sheet, a light source 2 and a liquid crystal sheet 3. The back light sheet is a transparent sheet in which a clad sheet 11 as a reflection layer, a core sheet 12 as a light transmission body layer and a cover sheet 13 as a scattering layer are laminated in this order by a film forming method. The clad sheet 11 is composed of soda glass of a thickness 1mm and its refractive index is 1.50. The core sheet 12 is obtd. by forming a thin film of a PMMA on the clad sheet 11 by a spin coating method. The film thickness of the core sheet 12 is 5μm and the refractive index thereof is 1.54. The cover sheet 13 is composed by forming a thin film of a PC on the core sheet 12 by a spin coating method. The film thickness thereof is 100μm and the refractive index thereof is 1.50. The refractive index of the core sheet 12 is larger than the refractive index of the layers on its both surfaces. |
