| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a zoom lens for projection and a projection type display device obtaining down sizing and making lighter weight by a lens composition of five groups of eight lenses and capable of carrying out a well balanced good correction of various aberrations, especially both the spherical aberration and the comatic aberration. <P>SOLUTION: The zoom lens for projection includes: a first negative group G<SB POS="POST">1</SB>composed of two lenses (L<SB POS="POST">1</SB>, L<SB POS="POST">2</SB>); a second group G<SB POS="POST">2</SB>composed of one positive lens; an aperture diaphragm 3; a third group G<SB POS="POST">3</SB>composed of one positive lens; a fourth group G<SB POS="POST">4</SB>composed of a lens No. 41 comprising a negative lens, a lens No. 42 arranged to form a negative air lens between the lens No. 41 and the lens No. 42, and a lens No. 43 comprising a positive lens; and a fifth group G<SB POS="POST">5</SB>composed of one positive lens with a convex surface facing the enlarging side in this order from an enlarging side and a conditional expression (1) is satisfied. -0.6<(R<SB POS="POST">72</SB>+R<SB POS="POST">71</SB>)/(R<SB POS="POST">72</SB>-R<SB POS="POST">71</SB>)<0.6 (1) (where R<SB POS="POST">71</SB>is a curvature radius on an enlarging side surface of the lens No. 43, and R<SB POS="POST">72</SB>is a curvature radius on reduction side surface of lens No. 43) <P>COPYRIGHT: (C)2012,JPO&INPIT |
