| 摘要 |
PURPOSE:To enable an optional selection of distribution of transmitted light through a screen by constituting the screen of single element of lenticular lens and fresnel lens and making the lenticular lens special noncircular constitution. CONSTITUTION:This is to reduce manufacturing cost and transportation cost and enable an optional selection of distribution of transmitted light by constituting a screen of single element of lenticular lens and fresnel lens. A noncircular lenticular lens 11 is constituted on the projection side of a medium 1 and a fresnel lens 12 is formed on the opposite projection side. At the same time, the noncircular lenticular lens 11 is so formed that distribution of transmitted light can be selected freely within the range that value of beta exceeds 20 deg.. There are two ways of selecting distribution of light. One is to decrease it with increase of angle theta of visual field. Another is to keep it constant up to a specified angle theta of visual field and decrease it when this value is exceeded. |
