Projection zoom lens
AssigneeRicoh Company, Ltd.
InventorTakashi KUBOTA
Life of this patent
Estimating the term…
Abstract
Disclosed is a projection zoom lens used in an image display device configured to project an image onto a target projection surface and display a magnified image of the image, in which the projection zoom lens has a five-lens-group configuration in which first to fifth lens groups G1 to G5 are arranged from the magnification side toward the reduction side, and each of the constituent lens groups or lenses included in the lens groups has a combination of negative and positive refractive powers, and in the lens configuration, focal lengths of the constituent lens groups, relative travel distances, lens distances to the image display element, and constituent lens shapes are properly selected.
Claims1
A projection zoom lens used in an image display device configured to project an image onto a target projection surface and display a magnified image of the image, wherein
- the projection zoom lens has a five-lens-group configuration including first to fifth lens groups arranged from the magnification side toward the reduction side,
- the first lens group has negative refractive power,
- the second lens group has negative refractive power,
- the third lens group has positive refractive power, and
- a half field angle at a wide angle end:
- ωw, a focal length of the first lens group:
- f1, and a focal length of the second lens group:
- f2 satisfy the conditions:
- 34 degrees≦ωw<45 degrees (1-I)
- 0.1<f1/f2<1.0. (2-I)
Dependencies are inferred from the claim text.