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.
Claims79
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)
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 distance:
- Bf between an image display element and a lens surface farthest to the reduction side in the fifth lens group farthest to the reduction side, a focal length at the wide angle end:
- Fw, and a focal length of the first lens group:
- F1 satisfy the conditions:
- 1.9≦Bf/Fw (1-II)
- 1.2<|F1|/Fw<3.5. (2-II)
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,
- the fifth lens group is moved toward the magnification side when the magnification is changed from the wide angle end to the telephoto end, and
- a half field angle at the wide angle end:
- ωw satisfies the condition:
- 34 degrees≦ωw<45 degrees. (1-III)
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
- in magnification change, the first lens group is fixed, and each of the second to fifth lens groups are moved toward the reduction side or magnification side.
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,
- in the first lens group, a lens surface farthest to the magnification side is convex toward the magnification side and a lens surface farthest to the reduction side is concave toward the reduction side, and
- a half field angle at the wide angle end:
- ωw satisfies the condition:
- 34 degrees≦ωw<45 degrees. (1-IV)
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,
- the fourth lens group has negative refractive power, and
- in the first lens group, a lens surface farthest to the magnification side is convex toward the magnification side, and a lens surface farthest to the reduction side is concave toward the reduction side.
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,
- the third lens group is moved toward the magnification side and the fourth lens group is moved toward the magnification side when the magnification is changed from the wide angle end to the telephoto end, and
- a travel distance D3 of the third lens group in magnification change and a travel distance D4 of the fourth lens group in magnification change satisfy the condition:
- 0.05<D3/D4<1.10. (1-V)
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,
- the first lens group includes two or three lenses, and
- a half field angle at the wide angle end:
- ωw satisfies the condition:
- 34 degrees≦ωw<45 degrees. (1-VI)
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,
- one or more of the second to fifth lens groups are set to be negative lens groups each including four or more lenses and having negative refractive power, and
- refractive power arrangement of the first to fourth lenses from the magnification side among the four or more lenses included in the negative lens group is set to positive, negative, positive and negative or negative, positive, negative and positive.
Dependencies are inferred from the claim text.