| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a low-cost projection zoom lens which has a wide angle and brightness, and is compact, and is hard to receive the influence of the change in temperature, and can achieve excellent optical performance by using the minimum number of aspherical lenses; and a projection display device having the same. <P>SOLUTION: A projection zoom lens comprises, in order from an enlargement side, a first group G<SB POS="POST">1</SB>having negative reactive power, a second group G<SB POS="POST">2</SB>having positive reactive power, a third group G<SB POS="POST">3</SB>having positive reactive power, and a fourth group G<SB POS="POST">4</SB>having positive reactive power. Upon zooming, the first group G<SB POS="POST">1</SB>and the fourth group G<SB POS="POST">4</SB>are fixed, and both of the second group G<SB POS="POST">2</SB>and the third group G<SB POS="POST">3</SB>are moved toward the enlargement side along an optical axis Z while changing the distance therebetween in accordance with an operation from a wide-angle end to a telephoto end. Furthermore, the projection zoom lens meets the following conditional expression (1): 17<F<SB POS="POST">G3</SB>/fw(1), where F<SB POS="POST">G3</SB>denotes a focal length of the third group G<SB POS="POST">3</SB>and fw denotes a focal length of the entire system at the wide-angle end. <P>COPYRIGHT: (C)2012,JPO&INPIT |
