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US 6,606,201 B1Granted
Zoom lens system
AssigneeMinolta Co., Ltd.
InventorMasatoshi Hirose
Life of this patent
Estimating the term…
Abstract
A zoom lens system has, from an enlargement side to a reduction side, a first lens unit having negative optical power and succeeding lens units including at least two lens units having positive optical power, wherein in zooming, all of lens units having negative optical power and included in entire zoom lens system is stationary in zooming.
Claims19
A zoom lens system comprising from an enlargement side to a reduction side:
- a first lens unit having a negative optical power and being stationary in zooming;
- a second lens unit having a positive optical power;
- a third lens unit having a positive optical power;
- and
- a fourth lens unit having a positive optical power;
- wherein said fourth lens unit satisfies the following condition:
- 1.0<f4/fW<2.2
- wherein fW is the overall focal length of the zoom lens system at the wide-angle limit, and f4 is the focal length of the fourth lens unit.
5 more elements
A projector comprising:
- a zoom lens system for use as a projection optical system of a projector;
- and
- a display device for displaying an image to be projected;
- said zoom lens system comprising from an enlargement side to a reduction side:
- a first lens unit having a negative optical power;
- a second lens unit having a positive optical power;
- a third lens unit having a positive optical power;
- and
- a fourth lens unit having a positive optical power;
- wherein the first lens unit is stationary in zooming,
- wherein the first lens unit is moved in focusing,
- wherein the second lens unit and the third lens unit are moved along an optical axis in the same direction in zooming, and
- wherein the fourth lens unit satisfies the following condition:
- 1.0<f4/fW<2.2;
- where fW is the overall focal length of the zoom lens system at the wide-angle limit, and f4 is the focal length of the fourth lens unit.
12 more elements
A zoom lens system for use as a projection optical system of a projector comprising from an enlargement side to a reduction side:
- a first lens unit having a negative optical power;
- a second lens unit having a positive optical power;
- a third lens unit having a positive optical power;
- and
- a fourth lens unit having a positive optical power;
- wherein the first lens unit is stationary in zooming, and
- wherein the fourth lens unit satisfies the following condition:
- 1.0<f4/fW<2.2
- wherein fW is the overall focal length of the zoom lens system at the wide-angle limit, and wherein f4 is the focal length of the fourth lens unit.
6 more elements
Dependencies are inferred from the claim text.