Projection optical system and projector

Patent metadata

Field	Value
Publication number	US-10645353-B2
Application number	US-201916450013-A
Country	US
Kind code	B2
Filing date	Jun 24, 2019
Priority date	Oct 31, 2014
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

A projection optical system (10) projects from a first image plane (5) on a reducing side to a second image plane (6) on an enlargement side. The projection optical system (10) includes a first optical system (11) that includes a plurality of lenses and forms a first intermediate image (51) formed inside the first optical system (11) by light incident from the reducing side into a second intermediate image (52) on the enlargement side of the first optical system; a second optical system (12) that includes a first reflective surface (M1) with positive refractive power which is positioned further to the enlargement side than the second intermediate image (52); and a glass block (30) that is disposed between the first optical system (11) and the first reflective surface (M1), the glass block (30) passing light rays from the first optical system to the second intermediate image.

First claim

The invention claimed is:

1. A projection optical system that projects from a first image plane on a reducing side to a second image plane on an enlargement side, comprising:
a first optical system that includes a plurality of lenses and forms, by light incident from the reducing side, an intermediate image on the enlargement side of the first optical system;
a second optical system that includes a first reflective surface with positive power which is positioned further to the enlargement side than the intermediate image; and
a glass block that is disposed between the first optical system and the first reflective surface and passes rays from the first optical system to the intermediate image.

2. The projection optical system according to claim 1 ,
wherein an image height Ih of the first image plane and a diameter MR of the first reflective surface satisfy a following condition
2.0< MR/Ih< 4.5.

3. The projection optical system according to claim 1 ,
wherein a light emitting area Vs of the first image plane and an effective area Ms of the first reflective surface satisfy a following condition
1.0< Ms/Vs< 6.0.

4. The projection optical system according to claim 1 ,
wherein a light emitting area Vs of the first image plane and an area I 2 s of the intermediate image satisfy a following condition
1.0< I 2 s/Vs< 3.0.

5. The projection optical system according to claim 1 ,
wherein the glass block is disposed between the first optical system and the intermediate image.

6. The projection optical system according to claim 1 ,
wherein the glass block includes:
an incident surface on a first optical system side;
an exit surface on a first reflective surface side; and
a side surface that is between the incident surface and the exit surface and is at least partially inclined with respect to an optical axis between the first optical system and the first reflective surface.

7. The projection optical system according to claim 6 ,
wherein the side surface includes a surface that is inclined so as to be substantially parallel to lower rays of projecting light that reach the second image plane from the first reflective surface.

8. The projection optical system according to claim 6 ,
wherein the side surface includes an internally reflective surface that reflects rays that reach the first reflective surface from the first optical system.

9. The projection optical system according to claim 1 ,
wherein the glass block includes an incident surface on a first optical system side and an exit surface on a first reflective surface side, wherein the incident surface and the exit surface are parallel with each other and perpendicular to an optical axis.

10. The projection optical system according to claim 1 ,
wherein the glass block includes an incident surface on a first optical system side and an exit surface on a first reflective surface side, wherein the exit surface shifts to the incident surface toward perpendicular to an optical axis.

11. The projection optical system according to claim 1 ,
wherein the glass block includes an incident surface on a first optical system side and an exit surface on a first reflective surface side, wherein the exit surface shifts to the incident surface toward an opposite side to a projection side of an optical axis.

12. The projection optical system according to claim 1 ,
wherein a length GBL of the glass block along an optical axis between the first optical system and the first reflective surface and a length LML along the optical axis between the first optical system and the first reflective surface satisfy a following condition
0.1< GBL/LML< 0.9.

13. The projection optical system according to claim 1 ,
wherein a length GBL of the glass block along an optical axis between the first optical system and the first reflective surface, a length LML along the optical axis between the first optical system and the first reflective surface, and a refractive index GBn of the glass block satisfy a following condition
0.05< GBL/GBn/LML< 0.7.

14. The projection optical system according to claim 1 ,
wherein an Abbe number GBv of the glass block satisfies a following condition
30< GBv< 100.

15. The projection optical system according to claim 1 ,
wherein an optical path length OP 1 d of upper rays of a light flux at an image height at an outermost periphery between the first optical system and the first reflective surface and an optical path length OP 2 d of lower rays the light flux satisfy a following condition
1< OP 1 d/OP 2 d< 1.15.

16. A projector comprising:
the projection optical system according to claim 1 , and
a light modulator that forms an image on the first image plane.

Assignees

• Nittoh Inc

Inventors

• Matsuo Takahiko

Classifications

• G02B17/08

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

• G03B21/14

  Details · CPC title

• G03B21/00

  Projectors or projection-type viewers; Accessories therefor (devices for changing pictures G03B23/00) · CPC title

• G03B21/28

  Reflectors in projection beam {(in illumination beam G03B21/2066)} · CPC title

• G03B21/147

  Optical correction of image distortions, e.g. keystone · CPC title