PROJECTION LENS AND VIDEO ENLARGED PROJECTION SYSTEM USING THE SAME, AND VIDEO PROJECTOR AND PROJECTION TELEVISION USING THE VIDEO ENLARGED PROJECTION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a projection lens which has high optical performance and reduces the temperature drift of an optical focus while making a cost reduction possible.;SOLUTION: The projection lens of four-element configuration in four groups are formed with aspheric surfaces on at least one surface of each of a first group lens G1, a third group lens G3 and a fourth group lens G5. The lens is formed to satisfy conditional expressions: (1) 0.1f0/f10.2, (2) 0.78/f0/f20.82, (3) 0.3f0/f30.38, (4) -0.53f0/f4-0.47, and (5) e1d11.5 when the focal length the entire system is defined as f0, the focal length of the first group lens G1 as f1, the focal length of the second group lens G2 as f2, the focal length of the third group lens G3 as f3, the focal length of the fourth group lens G4 as f4, the central thickness of the first group lens G1 as d1, and the surface separation of at the maximum ray height of the first group lens G1 as el.;COPYRIGHT: (C)2004,JPO