Projection zoom lens and projection type display device

摘要

A projection zoom lens essentially consists of a negative first lens group, a positive second lens group through the fourth lens group that move along the optical axis while changing magnification, a fifth lens group that moves while changing magnification, and a positive sixth lens group disposed in this order from the magnification side, wherein
the projection zoom lens satisfies conditional formulas (1) and (2) below:
1.9where,

mk (k=2 through 5) is the absolute value of movement of the k-th lens group while changing magnification from the wide angle end to the telephoto end, and

fw: the focal length of the entire system at the wide angle end.

主权项

1. A projection zoom lens, in which the distances between respective adjacent lens groups change while changing magnification, consisting of a first lens group having a negative refractive power that is fixed while changing magnification, a second lens group having a positive refractive power that moves along the optical axis while changing magnification, a third lens group having a positive refractive power that moves along the optical axis while changing magnification, a fourth lens group having a positive refractive power that moves along the optical axis while changing magnification, a fifth lens group that moves along the optical axis while changing magnification, and a sixth lens group having a positive refractive power that is fixed while changing magnification, disposed in this order from the magnification side, wherein
the reduction side is configured to be telecentric; the numerical aperture of the zoom lens is configured to be constant over the entire zoom range; the amount of movement of the fourth lens group while changing magnification from the wide angle end to the telephoto end is the greatest among the amounts of movement of all of the lens groups; an aperture stop is positioned at the reduction side of the third lens group and at the magnification side of the fifth lens group; the third lens group includes a lens having a negative refractive power; the fifth lens group includes a lens having a negative refractive power, a lens having a positive refractive power, and a lens having a negative refractive power arranged in this order from the magnification side; and the projection zoom lens satisfies conditional formulas (1), (2), (3), (4), and (5) below:
1.9