PROJECTION OPTICAL SYSTEM AND PROJECTOR

摘要

To provide a projection optical system that can cover a wide range of magnification changes with a focus lens group in which the number of constituted lenses is decreased, and a projector including the projection optical system. A 1-2nd lens group as the focus lens group includes an F1 lens group configured of one positive lens, an F2 lens group configured of one positive lens and one negative lens, and an F3 lens group configured of one negative lens. At least the F2 lens group is caused to move when focusing is performed in response to a magnification change.

主权项

1. A projection optical system comprising, in order from a reduction side:
a first optical group that is configured of a plurality of lenses and has positive power; and a second optical group that has a reflective surface having a concave aspheric shape, wherein the first optical group is configured to have a 1-1st lens group which is fixed when focusing is performed in response to a magnification change and has positive power, and a 1-2nd lens group which, as a whole, has positive power, and wherein the 1-2nd lens group includes, in order from the reduction side, three lens groups of an F1 lens group configured of one positive lens, an F2 lens group configured of one positive lens and one negative lens, and an F3 lens group configured of one negative lens, and at least the F2 lens group is caused to move when focusing is performed in response to the magnification change.