Projection lens and projection-type display apparatus using the lens
AssigneeFUJIFILM Corporation
InventorChikara Yamamoto
Life of this patent
Estimating the term…
Abstract
A projection lens is composed of a positive first lens group, a negative second lens group, and a positive third lens group, which are sequentially arranged from the magnification side of the projection lens, and the reduction side of the projection lens is telecentric. Further, the following formulas (1) and (2) are satisfied: 0.30≦d23/f3≦0.65 (1); and 10≦|D12/ff| (2), where d23: space in air between the second lens group and the third lens group, f3: focal length of the third lens group, D12: total length of the first lens group and the second lens group in the direction of an optical axis, and ff: length from the most magnification-side surface in the entire system of the projection lens to a magnification-side focus position of the entire system.
Claims16
A projection lens comprising:
- a first lens group having positive refractive power;
- a second lens group having negative refractive power;
- and
- a third lens group having positive refractive power, which are sequentially arranged from the magnification side of the projection lens,
- wherein the reduction side of the projection lens is telecentric, and
- wherein the following formulas (1) and (2) are satisfied:
- 0.30≦d23/f3≦0.65 (1);
- and
- 10≦|D12/ff| (2), where
- d23:
- space in air between the second lens group and the third lens group,
- f3:
- focal length of the third lens group,
- D12:
- total length of the first lens group and the second lens group in the direction of an optical axis, and
- ff:
- length from the most magnification-side surface in the entire system of the projection lens to a magnification-side focus point of the entire system of the projection lens.
Dependencies are inferred from the claim text.