Zoom lens, projection display device, and imaging apparatus for forming an intermediate image

Patent metadata

Field	Value
Publication number	US-11280986-B2
Application number	US-201916686246-A
Country	US
Kind code	B2
Filing date	Nov 18, 2019
Priority date	Aug 30, 2016
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

A zoom lens forms an intermediate image at a position conjugate to a reduction side imaging plane and forms the intermediate image again on a magnification side imaging plane. The zoom lens includes a plurality of lens groups including at least two movable lens groups, which move by changing spacings between the groups adjacent to each other in a direction of an optical axis during zooming, at a position closer to the reduction side than the intermediate image. Among the plurality of lens groups, a final lens group closest to the reduction side has a positive refractive power, and remains stationary with respect to the reduction side imaging plane during zooming. The zoom lens satisfies predetermined conditional expressions (1) and (2) about the focal lengths of the movable lens groups.

First claim

What is claimed is:

1. A zoom lens that forms an intermediate image at a position conjugate to a reduction side imaging plane and forms the intermediate image again on a magnification side imaging plane, the zoom lens comprising:
a plurality of lens groups including at least two movable lens groups, which move by changing spacings between groups that are adjacent to each other in a direction of an optical axis during zooming, at a position closer to a reduction side than the intermediate image,
wherein among the plurality of lens groups, a final lens group closest to the reduction side remains stationary with respect to the reduction side imaging plane during zooming,
an element of the zoom lens positioned most toward a magnification side is a lens,
a total angle of view of the zoom lens is greater than or equal to 115 degrees, and
the following conditional expression (3) is satisfied,
6< fM/|fw|< 20  (3),

where
fM is a focal length of the final lens group, and
fw is a focal length of the zoom lens at a wide-angle end.

2. The zoom lens as defined in claim 1 , wherein:
the final lens group consists of one lens.

3. The zoom lens as defined in claim 1 , wherein:
the final lens group has a positive refractive power.

4. The zoom lens as defined in claim 1 , comprising four or five lens groups as a whole,
wherein distances between adjacent lens groups change in the direction of the optical axis during zooming.

5. The zoom lens according to claim 1 ,
wherein the following conditional expression (1) is satisfied,
0<| fw|/fA< 0.145  (1),

where
fA is a focal length of a movable lens group closest to the reduction side among the plurality of movable lens groups.

6. The zoom lens according to claim 1 ,
wherein the following conditional expression (2) is satisfied,
0.01<| fw|/fB< 0.2  (2),

where
fB is a focal length of a second movable lens group from the reduction side among the plurality of movable lens groups.

7. The zoom lens according to claim 1 ,
wherein the following conditional expression (5) is satisfied,
2< Bfw/|fw|   (5),

where Bfw is a back focal length of the zoom lens as an air conversion length at the wide-angle end.

8. The zoom lens according to claim 5 ,
wherein the following conditional expression (1-1) is satisfied,
0<| fw|/fA< 0.14  (1-1).

9. The zoom lens according to claim 6 ,
wherein the following conditional expression (2-1) is satisfied,
0.03<| fw|/fB< 0.16  (2-1).

10. The zoom lens according to claim 1 ,
wherein the following conditional expression (3-1) is satisfied,
7< fM/|fw|< 18  (3-1).

11. The zoom lens according to claim 7 ,
wherein the following conditional expression (5-1) is satisfied,
3< Bfw/|fw|< 11  (5-1).

12. The zoom lens according to claim 6 ,
wherein the following conditional expression (2-2) is satisfied,
0.01<| fw|/fB≤ 0.1  (2-2).

13. A projection display device comprising:
a light valve from which an optical image is output based on image data; and
the zoom lens according to claim 1 ,
wherein the imaging optical system projects the optical image, which is output from the light valve, onto a screen.

14. An imaging apparatus comprising the zoom lens according to claim 1 .

15. A zoom lens that forms an intermediate image at a position conjugate to a reduction side imaging plane and forms the intermediate image again on a magnification side imaging plane, the zoom lens comprising:
a plurality of lens groups including at least two movable lens groups, which move by changing spacings between groups that are adjacent to each other in a direction of an optical axis during zooming, at a position closer to a reduction side than the intermediate image,
wherein among the plurality of lens groups, a final lens group closest to the reduction side remains stationary with respect to the reduction side imaging plane during zooming,
an element of the zoom lens positioned most toward a magnification side is a lens,
a total angle of view of the zoom lens is greater than or equal to 115 degrees, and
the following conditional expression (4) is satisfied,
0< Y max/| exPw |<0.1  (4),

where
Ymax is an effective image circle radius on the reduction side, and
exPw is a distance on the optical axis from the reduction side imaging plane to a paraxial exit pupil position at a wide-angle end in a case where the reduction side is set as an exit side.

16. The zoom lens according to claim 15 ,
wherein the following conditional expression (4-1) is satisfied,
0 <Y max/| exPw|< 0.07  (4-1).

17. A projection display device comprising:
a light valve from which an optical image is output based on image data; and
the zoom lens according to claim 15 ,
wherein the imaging optical system projects the optical image, which is output from the light valve, onto a screen.

18. An imaging apparatus comprising the zoom lens according to claim 15 .

Assignees

• Fujifilm Corp

Inventors

• Amano Masaru
• Nagahara Akiko
• Nagatoshi Yukiko
• Inoue Kazuki

Classifications

• G02B15/142 Primary

  having two groups only · CPC title

• G02B15/145

  having five groups only · CPC title

• G02B13/16

  for use in conjunction with image converters or intensifiers {, or for use with projectors, e.g. objectives for projection TV} · CPC title

• G02B15/144 Primary

  having four groups only · CPC title

• G02B13/06

  Panoramic objectives; So-called "sky lenses" {including panoramic objectives having reflecting surfaces} · CPC title