| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection lens which is adjustable for a projection type display device excellent in portability, has a wide angle so as to make the size of an image large even in close-distance projection and can be made an extremely simple inexpensive system, while having excellent projection performance and to provide the projection type display device using the projection lens. SOLUTION: The projection lens includes, in order from an enlargement side, a negative lens L<SB>1</SB>having a concave surface on a reduction side, a positive lens L<SB>2</SB>having a convex surface on the reduction side, a negative lens L<SB>3</SB>, a positive lens L<SB>4</SB>having a convex surface on the reduction side; and a positive lens L<SB>5</SB>. The projection lens satisfies conditional expressions (1) to (4): 2.5<β/S<10.0 (1), 20<S/OBJ<140 (2), 60°<2ω(3), FH<BH (4), whereinβis a magnification ratio, S is the maximum length (inch) of an enlargement-side image, OBJ is an enlargement-side projection distance (m), 2ωis an enlargement-side field angle, FH is the maximum effective luminous flux height in a lens surface on the most enlargement side, and BH is the maximum effective luminous flux height in a lens surface on the most reduction side. COPYRIGHT: (C)2010,JPO&INPIT
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