| 摘要 |
PROBLEM TO BE SOLVED: To obtain an extremely simple and inexpensive projection lens that is adaptable for a projection display device excellent in portability, is made in a wide angle state so that image size may be large even in a short-distance projection, and is constituted of a small number of lenses though it has high performance; and to obtain a projection display device using the same. SOLUTION: The projection lens comprises, in order from an enlargement side, a negative plastic lens L<SB>1</SB>whose both surfaces are aspherical, a positive meniscus lens L<SB>2</SB>which turns its convex surface to a reduction side, a biconcave lens L<SB>3</SB>, biconvex lenses L<SB>4</SB>and L<SB>5</SB>, a cemented lens obtained by cementing a negative lens L<SB>6</SB>which turns its concave surface to the reduction side and a biconvex lens L<SB>7</SB>, and a biconvex lens L<SB>8</SB>, wherein the projection lens satisfies conditional expressions (1) to (4). The expression (1): 2.5<β/S<10.0. The expression (2): 20<S/OBJ<65. The expression (3): 60°<2ω. The expression (4): FH<BH. Provided thatβis enlarging magnification, S is maximum length (inch) of an enlargement-side image, OBJ is an enlargement-side projection distance (m), 2ωis an enlargement-side viewing angle, FH is maximum effective luminous flux height on a lens surface closest to the enlargement side, and BH is maximum effective luminous flux height on a lens surface closest to the reduction side. COPYRIGHT: (C)2010,JPO&INPIT
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