| US 7,460,301 B2 | ||
| Image display apparatus, and transmissive screen and reflecting mirror used for same | ||
| Daisuke Imafuku, Fujisawa (Japan); Hiroki Yoshikawa, Hiratsuka (Japan); and Tetsu Ohishi, Hiratsuka (Japan) | ||
| Assigned to Hitachi, Ltd., Tokyo (Japan) | ||
| Filed on Feb. 23, 2005, as Appl. No. 11/62,742. | ||
| Claims priority of application No. 2004-315002 (JP), filed on Oct. 29, 2004. | ||
| Prior Publication US 2006/0092510 A1, May 04, 2006 | ||
| Int. Cl. G03B 21/56 (2006.01); G03B 21/60 (2006.01); G02B 3/08 (2006.01) | ||
| U.S. Cl. 359—460 [359/457; 359/454; 359/742] | 4 Claims |
| 1. A screen onto which light from an image generation source is projected, said screen comprising:
a Fresnel lens sheet with concentric prisms each formed at the image-viewing side;
wherein centers of the concentric prisms are shifted from a center of said screen, and prism angles of the prisms change on
the same circumference, and
wherein, when a substantially elliptic reference line is placed on said Fresnel lens sheet, the prisms at positions where
they overlap the reference line have substantially the same required prism angle.
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