Variable magnification optical system for projection and projection-type display apparatus
AssigneeFUJIFILM Corporation
InventorYukiko NAGATOSHI
Life of this patent
Estimating the term…
Abstract
A variable magnification optical system for projection consists of a negative lens group and a positive lens group in this order from a magnification side. A distance on an optical axis between the negative lens group and the positive lens group changes during magnification change, and an entire system substantially consists of six lenses. The negative lens group consists of a first lens including an aspheric surface and a second lens that is a negative single lens in this order from the magnification side.
Claims14
A variable magnification optical system for projection consisting of:
- a negative lens group having negative refractive power;
- and.
- a positive lens group having positive refractive power in this order from a magnification side,
- wherein a distance on an optical axis between the negative lens group and the positive lens group changes during magnification change, and
- wherein an entire system substantially consists of six lenses and
- wherein the negative lens group consists of a first lens including an aspheric surface and a second lens that is a single lens having negative refractive power in this order from the magnification side, and
- wherein the first lens is made of plastic material, and
- wherein the following conditional expression (1) is satisfied:
- |fw/f1|<0.1 (1), where
- fw:
- a focal length of the entire system at a wide angle end, and
- f1:
- a focal length of the first lens.
A variable magnification optical system for projection consisting of:
- a negative lens group having negative refractive power;
- and
- a positive lens group having positive refractive power in this order from a magnification side,
- wherein a distance on an optical axis between the negative lens group and the positive lens group changes during magnification change, and
- wherein an entire system substantially consists of six lenses, and
- wherein the negative lens group consists of a first lens including an aspheric surface and a second lens that is a single lens having negative refractive power in this order from the magnification side, and
- wherein the positive lens group consists of a positive lens, a positive lens, a negative lens and a positive lens in this order from the magnification side, and
- wherein magnification is changed by moving the negative lens group and the positive lens group in the direction of an optical axis.
Dependencies are inferred from the claim text.