Real image type view finder

• US 6,560,036 B2
• Filed: 05/21/2001
• Issued: 05/06/2003
• Est. Priority Date: 05/22/2000
• Status: Expired due to Term

• Current Assignee: OM Digital Solutions Corporation
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Tochigi, Akiyoshi, Takahashi, Toshio
• Primary Examiner(s): Dang, Hung Xuan
• Assistant Examiner(s): Tra, Tuyen
• Application Number:
  US09/860,477
• Publication Number:
  US 20020001136A1
• Time in Patent Office: 715 Days
• Field of Search: 359/688, 359/658, 359/659, 359/678, 359/682, 359/683, 396/382, 396/384, 396/379
• US Class Current: 359/688
• CPC Class Codes: G02B 15/144109 arranged +--+
• CPC Class Codes: G02B 23/14 Viewfinders for photographic apparatus G03B13/02
• CPC Class Codes: G02B 23/145 Zoom viewfinders

Abstract

A real image type view finder comprising an objective optical system which has positive refractive power and forms an intermediate image, an image erecting optical system which erects the intermediate image and an eyepiece optical system which leads the intermediate image to an observer'"'"'s eye, in which the objective optical system comprises a first positive lens unit, a second negative lens unit, a third negative lens unit and a fourth positive lens unit, moves the second lens unit and the third lens unit for a magnification change, has a vari-focal ratio on the order of 4, and has favorable optical performance over an entire zooming region.

Claims

1. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which comprises at least a prism and erects said intermediate image; and

an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye,

wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (1);

2. A manufacturing method of real image type view finder comprising a step of:

performing diopter adjustments for the view finder for a first specification according to claim 1 and the view finder for a second specification which are two different specifications by changing locations of the first lens unit, the second lens unit and the third lens unit collectively of said objective optical system.

3. A manufacturing method of real image type view finder according to claim 2, wherein the view finder is manufactured so that the view finder for the first specification comprises a liquid crystal display element which is disposed in the vicinity of the intermediate image and the view finder for said second specification comprises an airspace in the vicinity of the intermediate image, and the first lens unit, the second lens unit and the third lens unit of said objective optical system for the first specification are located on an exit pupil side of the lens units for the second specification.

4. A manufacturing method of real image type view finder according to claim 1 comprising a step of;

performing diopter adjustment for the real image type view finder at an assembling stage by changing a location of said second lens unit independently or locations of the second lens unit and the third lens unit collectively of said objective optical system.

8. The real image type view finder according to claim 1 or 5, wherein the first lens unit and the fourth lens unit of said objective optical system are kept stationary during a magnification change.

10. The real image type view finder according to claim 1, 5 or 9, wherein said image erecting optical system comprises a roof reflecting surface and two reflecting surfaces, rays incident on an edge line of said roof reflecting surface are reflected at acute angles and said two reflecting surfaces reflect rays at obtuse angles.

11. The real image type view finder according to claim 1, 5 or 9, wherein said image erecting optical system comprises a first prism which has a spherical or aspherical surface of incidence.

12. The real image type view finder according to claim 1, 5 or 9, wherein said image erecting optical system comprises a first prism which has a spherical or aspherical surface of incidence.

13. The real image type view finder according to claim 12, wherein said first prism is a fifth lens unit of said objective optical system.

14. The real image type view finder according to claim 1, 5 or 9, wherein diopter adjustment for a first specification and a second specification which are two different specifications is performed by changing locations of said first lens unit, second lens unit and third lens unit collectively.

15. The real image type view finder according to claim 14, wherein said first specification comprises a liquid crystal display element, and locations of the first, second and third lens units for said second specification are on an exit pupil side of locations of the first, second and third lens units for said first specification.

16. The real image type view finder according to claim 1, 5 or 9, wherein the view finder is configured to permits performing diopter adjustment at an assembling stage by changing a location of the second lens unit independently or locations of the second lens unit and the third lens unit integrally of said objective optical system.

17. The real image type view finder according to claim 1, 5 or 9, wherein flare stops which intercept unwanted rays are disposed on all the lens units of the objective optical system which is disposed on the object side of said image erecting optical system.

18. The real image type view finder according to claim 1, 5 or 9, wherein an aperture stop which has variable aperture diameter is disposed in said objective optical system.

19. The real image type view finder according to claim 1, 5 or 9, wherein each lens unit of said objective optical system consists only of a lens element.

20. The real image type view finder according to claim 1, 5 or 9, wherein the objective optical system has a van-focal ration of 3.5 or higher.

33. An image pickup apparatus including a real image type view finder according to claim 1, 5, 9, 22, 26, 27, 28, 29, 30, 31 or 32 comprising:

a photographic optical system which is disposed separately from said view finder.

5. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which comprises at least a prism and erects said intermediate image; and

an eyepiece optical which leads said intermediate image to an observer'"'"'s eye, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit in an identical direction along an optical axis and satisfies the following condition (2);

6. The real image type view finder according to claim 5 satisfying the following condition (3):

7. The real image type view finder according to claim 5, wherein each lens unit disposed in said objective optical system consists of a lens element and satisfies the following condition (4) and (5):

9. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which comprises at least a prism and erects said intermediate image; and

an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (6);

21. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which erects said intermediate image; and

an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9);

22. A real image type view finder comprising:

a photographic optical system;

an objective optical system which is disposed separately from the photographic optical system and forms an intermediate image;

a visual field frame which is disposed in the vicinity of said intermediate image;

an image erecting optical system which erects said intermediate image; and

an eyepiece optical system, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, and satisfies the following condition (7);

23. The real image type view finder according to claim 22, wherein said objective optical system changes a focal length by moving at least two lens units along different loci.

24. The real image type view finder according to claim 22 satisfying the following condition (8):

25. The real image type view finder according to claim 24 satisfying, in place of the condition (8), the following condition (8-1):

26. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which erects said intermediate image; and

an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9);

27. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has a positive refractive power;

an image erecting optical system which comprises at least a prism and erects said intermediate image;

an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye; and

an optical member which is disposed in the vicinity of said intermediate image separately from said prism,

wherein said optical member is exchangeable independently with another optical member for an identical specification, and

wherein an aperture stop which has variable aperture diameter is disposed in said objective optical system.

28. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which erects said intermediate image; and

an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye,

wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9);

29. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which erects said intermediate image and an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye,

wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9);

30. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which comprises at least a prism and erects said intermediate image;

an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye; and

an optical member which is disposed in the vicinity of said intermediate image separately from said prism,

wherein said optical member is exchangeable independently with another optical member for an identical specification, and wherein the objective optical system has a van-focal ratio of 3.5 or higher.

31. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which erects said intermediate image; and

an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye,

wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9);

32. A real image type view finder comprising:

an objective optical system which forms an intermediate image and has positive refractive power;

an image erecting optical system which comprises at least a prism and erects said intermediate image;

an eyepiece optical system which leads said intermediate image to an observer'"'"'s eye; and

an optical member which is disposed in the vicinity of said intermediate image separately from said prism, and

wherein the objective optical system has a van-focal ratio of 3.5 or higher.