Lens for projection and projection-type display apparatus
AssigneeFUJIFILM Corporation
InventorChikara Yamamoto
Life of this patent
Estimating the term…
Abstract
A lens for projection substantially consists of a negative first lens with its concave surface facing a reduction side, a positive second lens with its concave surface facing the reduction side, a negative third lens with its concave surface facing a magnification side, a positive fourth lens with its convex surface facing the reduction side, a positive fifth lens and a positive sixth lens in this order from the magnification side. The reduction side is telecentric. The following conditional formulas (1) and (2) about refractive power P4 of a reduction-side surface of the second lens, refractive power P5 of a magnification-side surface of the third lens, and focal length f of an entire system are satisfied: −3.0≦1/(P4×f)≦−0.4 (1); and −2.0≦1/(P5×f)≦−0.2 (2).
Claims19
A lens for projection consisting of six lenses of:
- a first lens having negative refractive power with a concave surface facing a reduction side;
- a second lens having positive refractive power with a concave surface facing the reduction side;
- a third lens having negative refractive power with a concave surface facing a magnification side;
- a fourth lens having positive refractive power with a convex surface facing the reduction side;
- a fifth lens having positive refractive power;
- and
- a sixth lens having positive refractive power, in this order from the magnification side,
- wherein the following conditional formulas (1) and (2) are satisfied:
- −3.0≦1/(P4xf)≦−0.4 (1);
- and
- −2.0≦1/(P5xf)≦−0.2 (2), where
- P4:
- refractive power of a reduction-side surface of the second lens,
- P5:
- refractive power of a magnification-side surface of the third lens, and
- f:
- a focal length of an entire system,
- wherein the following conditional formula (3′) is satisfied:
- 0.5≦Bf/f≦1.5 (3′), where
- Bf:
- a back focus of the entire system (a distance in air).
A lens for projection consisting of six lenses of:
- a first lens having negative refractive power with a concave surface facing a reduction side;
- a second lens having positive refractive power with a concave surface facing the reduction side;
- a third lens having negative refractive power with a concave surface facing a magnification side;
- a fourth lens having positive refractive power with a convex surface facing the reduction side;
- a fifth lens having positive refractive power;
- and
- a sixth lens having positive refractive power, in this order from the magnification side,
- wherein the reduction side is telecentric, and
- wherein the following conditional formulas (1) and (2) are satisfied:
- −3.0≦1/(P4xf)≦−0.4 (1);
- and
- −2.0≦1/(P5xf)≦−0.2 (2), where
- P4:
- refractive power of a reduction-side surface of the second lens,
- P5:
- refractive power of a magnification-side surface of the third lens, and
- f:
- a focal length of an entire system,
- wherein the following conditional formula (6) is satisfied:
- 1.0≦f2/f≦2.0, where
- f2:
- a focal length of the second lens.
A lens for projection consisting of six lenses of:
- a first lens having negative refractive power with a concave surface facing a reduction side;
- a second lens having positive refractive power with a concave surface facing the reduction side;
- a third lens having negative refractive power with a concave surface facing a magnification side;
- a fourth lens having positive refractive power with a convex surface facing the reduction side;
- a fifth lens having positive refractive power;
- and
- a sixth lens having positive refractive power, in this order from the magnification side,
- wherein the reduction side is telecentric, and
- wherein the following conditional formulas (1) and (2) are satisfied:
- −3.0≦1/(P4xf)−0.4 (1);
- and
- −2.0≦1/(P5xf)≦−0.2 (2), where
- P4:
- refractive power of a reduction-side surface of the second lens,
- P5:
- refractive power of a magnification-side surface of the third lens, and
- f:
- a focal length of an entire system,
- wherein the third lens and the fourth lens are cemented together in contact with each other with abutting lens surfaces and the radii of curvature of the abutting lens surfaces are identical.
A lens for projection consisting of six lenses of:
- a first lens having negative refractive power with a concave surface facing a reduction side;
- a second lens having positive refractive power with a concave surface facing the reduction side;
- a third lens having negative refractive power with a concave surface facing a magnification side;
- a fourth lens having positive refractive power with a convex surface facing the reduction side;
- a fifth lens having positive refractive power;
- and
- a sixth lens having positive refractive power, in this order from the magnification side,
- wherein the reduction side is telecentric, and
- wherein the following conditional formulas (1) and (2) are satisfied:
- −3.0≦1/(P4xf)≦−0.4 (1);
- and
- −2.0≦1/(P5xf)−0.2 (2), where
- P4:
- refractive power of a reduction-side surface of the second lens,
- P5:
- refractive power of a magnification-side surface of the third lens, and
- f:
- a focal length of an entire system,
- wherein the following conditional formula (7) is satisfied:
- vd2≦25.4 (7), where
- vd2:
- an Abbe number of the second lens for d-line.
Dependencies are inferred from the claim text.