| 摘要 |
PURPOSE:To improve transmittivity of light and to facilitate forming by forming a minute prism-like Fresnel surface. CONSTITUTION:First of all, a die of a thin linear lens formed by fining a pitch of a lens (linear lens) formed by developing a cylindrical Fresnel lens 1 to a plane is made, and subsequently, a sheet-like linear lens 1' is made by heating and pressing a flexible plastic sheet, and it is formed to a cylindrical shape by bending it so that a Fresnel center line 11 obtain a shape like a horizontal ring. Since the Fresnel surface of the cylindrical Fresnel lens 1 is a minute prism-like Fresnel surface, it will suffice that the light emitting surface 12 is a straight line in the longitudinal section, the lens can be designed easily, working of the die can also be executed easily by a planer or a lathe, and a sheet-like flexible linear lens can be formed easily. In such a way, a cylindrical lens which can be manufactured easily, which is economical, and which is excellent in transmittivity of light is obtained. |
