| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a zoom lens which has high performance and a small lens aperture, and is suitable for a thin-type projection display device, wherein an image is magnified and projected onto a screen or the other, and to provide the projection display device using the zoom lens. <P>SOLUTION: The zoom lens, whose magnification can be varied, includes, in order from a magnifying side: a first lens group having negative refractive power as a whole; a second lens group having positive refractive power as a whole; a third lens group having positive refractive power as a whole; a fourth lens group having positive refractive power as a whole; and a fifth lens group having positive refractive power as a whole. The first lens group is fixed in operation of varying magnification. The second, third, fourth, and fifth lens groups are moved on an optical axis from a reducing side to a magnifying side, and thereby the variation of magnification in the entire system of the lens is achieved. <P>COPYRIGHT: (C)2011,JPO&INPIT |
