Patent ID: 9638903
Date: 2017-05-02
CPC Classifications: G02B

Claim:
1. 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 a magnification side toward a 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 magnification change, the first lens group is fixed, and the second to fourth lens groups are moved toward the reduction side or the magnification side, the fifth lens group is monotonously moved toward the magnification side in the magnification change from a wide angle end to a telephoto end, the fourth lens group has positive refractive power, the fifth lens group has positive refractive power, in magnification change from the wide angle end to the telephoto end, the second lens group is moved toward the reduction side, the third lens group is moved toward the magnification side, and the fourth lens group is moved toward the magnification side, and the fifth lens group has the weakest power (1/focal length) of all the lens groups.