Image-forming optical system, projection device, and imaging device

Patent metadata

Field	Value
Publication number	US-12487436-B2
Application number	US-202118019712-A
Country	US
Kind code	B2
Filing date	Aug 3, 2021
Priority date	Aug 5, 2020
Publication date	Dec 2, 2025
Grant date	Dec 2, 2025

Abstract

An image formation optical system includes a first optical system, in which a first refractive system is arranged toward the reduction side of an intermediate image and a second refractive system is arranged toward the magnification side of the intermediate image, and the first refractive system has a first stop, and the second refractive system has a second stop. Lens surfaces are arranged next to and both toward the reduction side and toward the magnification side of the first stop and the second stop, and the following condition is satisfied:

1.5< Y 1-1 (unit of mm), where
Y1-1 is the absolute value of the ray height of a principal ray at an outermost angle of view in rays emitted from a lens surface arranged next to and toward the reduction side of the first stop.

First claim

The invention claimed is:

1 . An image formation optical system configured to form an image of a reduction-side conjugate surface on a magnification-side conjugate surface, the image formation optical system comprising:
a first optical system including an intermediate image inside and also a first refractive system arranged toward the reduction side of the intermediate image and a second refractive system arranged toward the magnification side of the intermediate image, wherein the first refractive system has a first stop, and the second refractive system has a second stop, wherein lens surfaces are arranged next to and both toward the reduction side and toward the magnification side of the first stop and lens surfaces are arranged next to and both toward the reduction side and toward the magnification side of the second stop, wherein the following Formula (1) through (8) are satisfied:
1.5< Y 1-1  (1);

1.5< Y 1-2  (2);

1.0< Y 2-1  (3); and

0.5< Y 2-2  (4), where

0.5< Y 1-1/| fW|   (5),

0.5< Y 1-2/| fw|   (6),

0.3< Y 2-1/| fw|   (7), and

0.1< Y 2-2/| fw|   (8), where

Y1-1: the absolute value of the ray height of a principal ray at an outermost angle of view in rays emitted from a lens surface 1 arranged next to and toward the reduction side of the first stop (unit of mm), Y1-2: the absolute value of the ray height of a principal ray at an outermost angle of view in rays entering a lens surface 2 arranged next to and toward the magnification side of the first stop unit of mm), Y2-1: the absolute value of the ray height of a principal ray at an outermost angle of view in rays emitted from a lens surface 3 arranged next to and toward the reduction side of the second stop (unit of mm), Y2-2: the absolute value of the ray height of a principal ray at an outermost angle of view in rays entering a lens surface 4 arranged next to and toward the magnification side of the second stop (unit of mm), and fw: a focal length of the entire system when focusing at closet at wide-angle end.

2 . The image formation optical system, as defined in claim 1 , wherein the following Formula (14) through (16), and (18) are satisfied:
1.0<tan θ1×| fw|< 3.0  (14);
2.5<tan θ2×| fw|< 6.0  (15);
1.5<tan θ2/tan θ1<4.0  (16), and
8.0< Ds 2×tan θ2<30.0  (18), where
θ1: an incident angle on the first stop of a principal ray at an outermost angle of view, θ2: an incident angle on the second stop of a principal ray at an outermost angle of view, fw: a focal length of the entire system when focusing at wide-angle end at closest, and Ds2: D2-1+D2−2.

3 . An image formation optical system configured to form an image of a reduction-side conjugate surface on a magnification-side conjugate surface, the image formation optical system comprising:
a first optical system including an intermediate image inside and also a first refractive system arranged toward the reduction side of the intermediate image and a second refractive system arranged toward the magnification side of the intermediate image, wherein the first refractive system has a first stop, and the second refractive system has a second stop, wherein lens surfaces are arranged next to and both toward the reduction side and toward the magnification side of the first stop and lens surfaces are arranged next to and both toward the reduction side and toward the magnification side of the second stop, wherein the following Formula (1) through (4) are satisfied:
1.5< Y 1-1  (1);

1.5< Y 1-2  (2);

1.0< Y 2-1  (3); and

0.5< Y 2-2  (4), where

Y1-1: the absolute value of the ray height of a principal ray at an outermost angle of view in rays emitted from a lens surface 1 arranged next to and toward the reduction side of the first stop (unit of mm), Y1-2: the absolute value of the ray height of a principal ray at an outermost angle of view in rays entering a lens surface 2 arranged next to and toward the magnification side of the first stop (unit of mm), Y2-1: the absolute value of the ray height of a principal ray at an outermost angle of view in rays emitted from a lens surface 3 arranged next to and toward the reduction side of the second stop (unit of mm), and Y2-2: the absolute value of the ray height of a principal ray at an outermost angle of view in rays entering a lens surface 4 arranged next to and toward the magnification side of the second stop (unit of mm), wherein when two lenses comprising a first adjacent lens arranged next to and toward the reduction side of the first stop and a second adjacent lens arranged next to and toward the reduction side of the first adjacent lens are regarded as a group 1, two lenses comprising a first adjacent lens arranged next to and toward the magnification side of the first stop and a second adjacent lens arranged next to and toward the magnification side of the first adjacent lens are regarded as a group 2, two lenses comprising a first adjacent lens arranged next to and toward the reduction side of the second stop and a second adjacent lens arranged next to and toward the reduction side of the first adjacent lens are regarded as a group 3, and two lenses comprising a first adjacent lens arranged next to and toward the magnification side of the second stop and a second adjacent lens arranged next to and toward the magnification side of the first adjacent lens are regarded as a group 4, the lenses included in the groups 1, 2, 3 and 4 satisfy the following Formula (25) or (26):
40≤ν d and 0.97<τ420  (25); or

ν d< 40 and 0.90<τ420  (26), where

vd: Abbe's number of an optical material constituting a lens, and τ420: an internal transmittance of an optical material having a thickness of 10.0 mm at the wavelength of 420 nm.

4 . The image formation optical system, as defined in claim 3 , wherein when the Formula (26) is satisfied, the following Formula (27) is satisfied:
ν d< 40 and 0.93<τ420  (27).

5 . The image formation optical system, as defined in claim 3 , wherein when the temperature coefficient of a relative refractive index of the optical material is dn/dt, the lenses in all the lens groups satisfy the following Formula (28):
| dn/dt|< 6.5  (28).

6 . The image formation optical system, as defined in claim 1 , comprising:
at least one zoom group configured to move during magnification change, wherein the at least one zoom group comprises a first zoom group, which has a largest number of lenses among zoom groups arranged toward the reduction side of the stop in the first refractive system and has a positive focal length, and wherein the first zoom group does not include lens toward the magnification side of the first stop but includes a lens or lenses toward the reduction side of the first stop.

7 . The image formation optical system, as defined in claim 6 , wherein a fixed group 1 that has a positive focal length and does not move during magnification change is arranged most toward the reduction side in the image formation optical system and wherein the fixed group 1 includes at least one negative lens.

8 . The image formation optical system, as defined in claim 6 , comprising:
a second zoom group arranged next to and toward the magnification side of the first stop, wherein the second zoom group comprises a positive lens or lenses.

9 . The image formation optical system, as defined in claim 8 , wherein the positive lens or lenses constituting the second zoom group comprise a positive meniscus lens or lenses with a concave surface or surfaces directed to the image side.

10 . The image formation optical system, as defined in claim 8 , wherein the first zoom group and the second zoom group move inde

Assignees

• Nittoh Inc

Inventors

• Matsuo Takahiko

Classifications

• G02B7/04

  with mechanism for focusing or varying magnification · CPC title

• G02B15/143103

  arranged ++- · CPC title

• G02B15/20

  having an additional movable lens or lens group for varying the objective focal length · CPC title

• G02B17/08

  Catadioptric systems {(used in non-imaging applications G02B19/00)} · CPC title

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title