| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technology suitable for projecting images on a screen brighter while reducing the depth of a device. <P>SOLUTION: The Fresnel lens sheet 31 has the Fresnel center o located near the lower end of the Fresnel lens sheet, and includes a first concentric circular Fresnel lens located inside a reference circle n and a second concentric circular Fresnel lens located outside the reference circle n. The conjugate point distance of the second Fresnel lens is made shorter than that of the first Fresnel lens. The reference circle n is the circle of the Fresnel lens, which passes the vicinities of the intersections of the horizontal center line m vertically bisecting the Fresnel lens sheet 31 and the left end and right end of the Fresnel lens sheet. <P>COPYRIGHT: (C)2007,JPO&INPIT |
