| 摘要 |
PROBLEM TO BE SOLVED: To obtain a wide-angle projection lens having high projection performance while securing a long back focus, and also, capable of using an inexpensive light reflection mirror as an optical path bending component, and whose manufacturing cost is reduced. SOLUTION: The projection lens is constituted by arraying a first group G<SB>1</SB>having negative refractive power and a second group G<SB>2</SB>having positive refractive power in order from an enlargement side, the projection lens is nearly telecentric on a reduction side. The first group G<SB>1</SB>comprises at least seven lenses in order from the enlargement side, that is, an aspheric lens L<SB>1</SB>, a negative meniscus lens L<SB>2</SB>with a convex surface facing the enlargement side, negative lenses L<SB>3</SB>and L<SB>4</SB>each with a concave surface facing the reduction side, a negative lens L<SB>5</SB>with a concave surface facing the reduction side, a biconvex lens L<SB>6</SB>and a negative lens L<SB>7</SB>with a concave surface facing the enlargement side (three-cemented lens composed of lenses L<SB>5</SB>, L<SB>6</SB>and L<SB>7</SB>). Further, the projection lens satisfies three conditional expressions (1) to (3). COPYRIGHT: (C)2009,JPO&INPIT
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