| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a light diffusion sheet preventing decrease in surface luminance or deterioration of contrast due to stray light and having less angle dependence and less scattering reflection of external light, and to provide a projection screen using the light diffusion sheet. <P>SOLUTION: The light diffusion sheet includes a plurality of unit lenses one-dimensionally or two-dimensionally formed thereon and is such that each unit lens is substantially trapezoidal in the cross section; the lower bottom of the trapezoid is made to be a light incidence portion and the upper bottom thereof is made to be a light emission portion; the unit lens is formed using a material having a predetermined refractive index N1; a transparent low refractive index layer having a refractive index N2 lower than N1 is formed in a slope portion of the trapezoid; a portion with a triangular cross section, located in between adjacent unit lenses is filled with a material having a refractive index higher than N2; the material having the refractive index higher than N2 includes dispersion of light-absorbing particles; and when an angle defined by the slope of the trapezoid and a normal line of the light-emitting portion is represented by θ, it satisfies the relations sin(90°-θ)>N2/N1 and N1<1/sin2θ. <P>COPYRIGHT: (C)2009,JPO&INPIT |
