| 摘要 |
PURPOSE:To pevent the deterioration of contract due to the external light to reduce a luminous flux loss then to improve the luminance distribution and to facilitate easy recovery for damage of a screen, by forming a Fresnel surface at the light source side of a transparent resin plate containing a diffusion layer. CONSTITUTION:A transmissive screen 41 has an equi-diffusion layer 43 formed inside an acrylic resin thin plate arranging a FResnel lens surface 42 at the light source side and has a viewing surface 44 finished into a mirror surface. In the production steps, the glass plates for cast molding tool are set in parallel to each other with a space slightly smaller than the thickness of a complete screen. The fused acrylic resin is casted between the parallel glass plates and hardened. Then the glass plate pair is opened slightly, and then acrylic resin mixed with a pigment, etc. is casted into a mold and hardened with no mixture to the part already casted into the mold in order to obtain the diffusion characteristics.One side of the substrate transparent surface is pressed with a Fresnel type frame to obtain a Fresnel lens. The viewing surface of the screen is finished into a mirror surface and does not relfect the incident light of an angle larger than the critical value. |
