Zoom lens and projection display device using the same
AssigneeFuji Photo Optical Co., Ltd.
InventorAkiko Nagahara
Life of this patent
Estimating the term…
Abstract
A zoom lens includes, in order from the enlarging side: a first lens group that has negative refractive power, is movable for focusing, and is stationary during zooming; second, third, and fourth lens groups that are movable for zooming; and a fifth lens group that is stationary during zooming. The second, third, fourth, and fifth lens groups have positive refractive powers. The second, third, and fourth lens groups move nearer the enlarging side when the zoom lens zooms toward the telephoto end. The ratios of the focal lengths of the first, first through third, fourth, and fifth lens groups to the focal length of the zoom lens satisfy four conditions. The fourth lens group is a biconvex lens element. A projection display device uses the zoom lens.
Claims24
A zoom lens for enlarging an image comprising, in order from the enlarging side to a reducing side without any intervening lens element:
- a first lens group having negative refractive power that is movable for focusing and that is stationary during zooming;
- a second lens group having positive refractive power that moves during zooming;
- a third lens group having positive refractive power that moves during zooming;
- a fourth lens group having positive refractive power that moves during zooming;
- and
- a fifth lens group having positive refractive power that is stationary during zooming;
- wherein
- said second lens group, said third lens group, and said fourth lens group move relative to one another along the optical axis of the zoom lens during zooming.
A zoom lens for enlarging an image comprising, in order from the enlarging side to a reducing side and with no intervening lens elements:
- a first lens group having negative refractive power that is movable for focusing and that is stationary during zooming;
- a second lens group having positive refractive power that moves during zooming;
- a third lens group having positive refractive power that moves during zooming;
- a fourth lens group having positive refractive power that moves during zooming;
- and
- a fifth lens group having positive refractive power that is stationary during zooming;
- wherein
- said second lens group, said third lens group, and said fourth lens group move relative to one another along the optical axis of the zoom lens during zooming.
A zoom lens for enlarging an image consisting of, in order from the enlarging side to a reducing side:
- a first lens group having negative refractive power that is movable for focusing and that is stationary during zooming;
- a second lens group having positive refractive power that moves during zooming;
- a third lens group having positive refractive power that moves during zooming;
- a fourth lens group having positive refractive power that moves during zooming;
- and
- a fifth lens group having positive refractive power that is stationary during zooming;
- wherein
- said second lens group, said third lens group, and said fourth lens group move relative to one another along the optical axis of the zoom lens during zooming.
A zoom lens for enlarging an image comprising, in order from the enlarging side to a reducing side:
- a first lens group having negative refractive power that is movable for focusing and that is stationary during zooming;
- a second lens group having positive refractive power that moves during zooming;
- a third lens group having positive refractive power that moves during zooming;
- a fourth lens group having positive refractive power that moves during zooming;
- and
- a fifth lens group having positive refractive power that is stationary during zooming;
- wherein
- said second lens group, said third lens group, and said fourth lens group move relative to one another along the optical axis of the zoom lens during zooming;
- and
- said fourth lens group consists of a single positive lens component.
A zoom lens for enlarging an image comprising, in order from the enlarging side to a reducing side:
- a first lens group having negative refractive power that is movable for focusing and that is stationary during zooming;
- a second lens group having positive refractive power that moves during zooming;
- a third lens group having positive refractive power that moves during zooming;
- a fourth lens group having positive refractive power that moves during zooming;
- and
- a fifth lens group having positive refractive power that is stationary during zooming;
- wherein
- said second lens group, said third lens group, and said fourth lens group move relative to one another along the optical axis of the zoom lens during zooming;
- said fourth lens group consists of a single positive lens component;
- and
- the following conditions are satisfied:
- 0.8<|F1|/F<1.2
- 1.3<F5/F<2.3
- and
- 2.0<F(1-3)/F
- where
- F1 is the focal length of said first lens group,
- F is the focal length of the zoom lens at the wide-angle end when the zoom lens is focused at infinity on the enlarging side,
- F5 is the focal length of said fifth lens group, and
- F(1-3) is the composite focal length of said first lens group, said second lens group, and said third lens group at the wide-angle end when the zoom lens is focused at infinity on the enlarging side.
Dependencies are inferred from the claim text.