| 摘要 |
PURPOSE: To make a luminance distribution substantially uniform with an illumination device to be used as a back light of a liquid crystal display device. CONSTITUTION: An optical system for forming a surface light source consisting of a light transmission plate 8, a reflection plate 9 and a diffusion plate 10 is subjected to at least one of prescribed optical working among light absorption working, light diffusion working and light reflection working in such a manner that the luminance distribution emitted from the surface of a liquid crystal display panel 4 is uniformly visible according to the irradiation quantity and calorific value of an L-shaped fluorescent tube 11 and the luminance characteristics of the liquid crystal display panel 4. As a result, each optically observed luminance in the remaining eight divided regions attains the luminance as shown in (A) when the display region of the liquid crystal display panel 4 is divided to three regions each longitudinally and transversely and total nine divided regions as shown in alternate long and short dash lines in (A) as an example and the optically measured luminance of the divided region in the central part is assumed to be 100%. |
