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.
Claims15
A projection zoom lens, comprising, in order from a magnification side to a reduction side:
- a first lens group having negative refraction power;
- a second lens group having negative refraction power;
- a third lens group having positive refraction power;
- a fourth lens group having positive refraction power;
- and
- a fifth lens group,
- wherein, when magnification is changed from a wide angle end to a telephoto end, the first lens group is fixed and the fifth lens group moves in an optical axis direction,
- wherein, when the magnification is changed from the wide angle end to the telephoto end, the second lens group moves toward the reduction side, the third lens group moves toward the magnification side, and the fourth lens group moves toward the magnification side, and
- wherein the fifth lens group has the smallest refraction power among the first, second, third, and fourth lens group.
Dependencies are inferred from the claim text.