| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a Fresnel lens sheet, transmission type screen, and back projection type display device that can significantly reduce display defects such as ghost and can display excellent videos.SOLUTION: A Fresnel lens layer 22 has a plurality of unit lenses 22a each having a lens surface 22b and non-lens surface 22c arranged on a Fresnel base material layer 21, and when the distance between a light source unit 70 and the optical center F in the Fresnel lens shape is W, the distance between the optical center F and the incident position of video light L of the Fresnel lens layer 22 is R, the angle of a light emission surface of the Fresnel base material layer 21 at the incident position isθs, the refractive index of light in the air is n, the refractive index of light on the Fresnel lens layer 22 is n, the angle of a lens surface 22b isα, the angle of a non-lens surface 22c isβ,θ=arctan(R/W),θ'=θ-θ,θ=arcsin(n/n×sinθ'),θ=α-θ, andθ=arcsin(n/n×sinθ), the Fresnel lens layer 22 satisfiesβ≥α-θ.</p> |
