| 摘要 |
PROBLEM TO BE SOLVED: To facilitate manufacturing a unit prism even if its apex angle is acute, and to decrease resin quantity used for reduction in manufacturing costs, dimensions, and weight, by arranging a flat surface of an approximately same height as a base end near one of the surfaces of the unit prism between adjacent unit prisms. SOLUTION: A lens film is formed by arraying many unit lenses 14 of a triangle pole form on one surface (bottom surface) of a transparent base sheet 12 in a one-dimensional direction so that their edge lines 14A are in parallel with each other, and this unit lenses 14 are arranged intermittently at regular intervals, and one surface of the transparent base sheet 12 is exposed and made to be a flat surface between each unit lens 14. In this case, the apex angle αof the unit lens 14 is made to an acute angle of 40 deg.-70 deg.. In such a manner, an incident light area on each unit lens 14 is increased in the rate to its height H. And, if an area for the incident light 20 is unchanged, the height of the unit lens 14 can, for example, be reduced to a level of approximately 1/3. |
