| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a Fresnel lens which has such a configuration that a degree of freedom in designing is high or a processing limit is hardly caused or the most suitable lens shape can be given to each of a plurality of adjacent light sources and to provide an illuminating device which has characteristics improved by using the Fresnel lens. <P>SOLUTION: The Fresnel lens is provided with a plurality of Fresnel lens surfaces provided with many annular prisms, on the surface of a transparent lens material. The Fresnel lens surfaces are provided on upper and lower surfaces of the lens material. The center axis of Fresnel lens surfaces provided on the upper surface and that on the lower surface are shifted from each other by a prescribed distance. Center axes of the plurality of Fresnel lens surfaces are shifted from each other by a prescribed distance. The Fresnel lens surfaces are put on curved surfaces. In the illuminating device, the Fresnel lens having one of these features is arranged nearly right above the light emitting surface of a LED element. The illuminating device has this configuration arranged in an array. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
