ND filter and aperture device using the same

• US 5,479,298 A
• Filed: 09/08/1994
• Issued: 12/26/1995
• Est. Priority Date: 12/20/1991
• Status: Expired due to Term

• Current Assignee: Canon Hi-Tech Limited (Canon Inc.)
• Original Assignee: Canon Hi-Tech Limited (Canon Inc.)
• Inventors: Kawakami, Yoshio, Nozue, Hitoshi, Yanagi, Michio
• Primary Examiner(s): Dzierzynski, Paul M.
• Assistant Examiner(s): Chang, Audrey Y.
• Application Number:
  US08/302,946
• Time in Patent Office: 474 Days
• Field of Search: 359/888, 359/889, 359/894, 359/558, 359/562, 359/41, 359/43, 359/72
• US Class Current: 359/888
• CPC Class Codes: G02B 27/0018 with means for preventing ghost images anti-reflection coatings G02B1/11
• CPC Class Codes: G02B 5/22 Absorbing filters G02B5/201 - G02B5/208 take precedence
• CPC Class Codes: G03B 9/06 Two or more co-operating pivoted blades, e.g. iris type shutters functioning as diaphragms by limiting extent of opening movement G03B9/08

Abstract

A plurality of darkness distributions having a predetermined relationship with a darkness distribution for ND-filtering transmission light at the position of an aperture blade in an aperture device are formed on an original. The original is photographed on a film by a camera, and after the film is developed, the film is molded to obtain a plurality of ND filters.

Claims

1. An aperture device having a ND filter being attached to a moveable member for adjusting a light amount, said ND filter being formed to have different transmission rates depending on regions,

said ND filter being formed from a developed film on which an original having a reflection darkness distribution having a predetermined relationship with said different transmission rates has been photographed by a camera, said film comprising a base having a transmission rate of not less than 80%, and an anti-halation layer, wherein said ND filter movably interlocks with a movable aperture member.

2. A device according to claim 1, wherein said film has a silver chloride particle size of not more than 0.5 μ

m.

3. A device according to claim 2, wherein said film has transmission spectral characteristics such that a variation in transmission rate in a wavelength range between 400 nm and 650 nm is not more than 20% as a ratio of a minimum transmission rate to a maximum transmission rate.

4. A device according to claim 1, wherein said film has transmission spectral characteristics such that a variation in transmission rate in a wavelength range between 400 nm and 650 nm is not more than 20% as a ratio of a minimum transmission rate to a maximum transmission rate.

5. A device according to claim 1, wherein a plurality of ND filter patterns are simultaneously photographed on said film, and the developed film is cut into a large number of ND filters.

6. A device according to claim 1, wherein said reflection darkness of said original is defined by connecting, in one direction, a constant-darkness region and a variable-darkness region in which a darkness is gradually lowered from the constant darkness.

7. A device according to claim 1, wherein a mark indicating a mounting position to an aperture blade after said film is cut in the form of said ND filter is formed on said ND filter on said film.

8. An aperture device having a ND filter being attached to a moveable member for adjusting a light amount, said ND filter comprising:

an original having a darkness distribution having a predetermined relationship with a darkness distribution for providing a ND filtering function; and

a diazo film exposed with an ultraviolet ray representing said darkness distribution of said original,

wherein said diazo film is developed and said developed film is cut in a form of a plurality of ND filters having the same density distribution.

9. A device according to claim 8, wherein a width of said ND filter is decreased in a direction in which a darkness is increased.

10. A device according to claim 8, wherein a plurality of lines of darkness distribution regions are formed on said original, a plurality of lines of darkness distribution regions are also formed on said developed film, and a large number of ND filters are obtained by cutting said film in units of lines of said plurality of lines of darkness distribution regions.

11. A device according to claim 10, wherein said darkness distribution is formed, so that a transmission rate of said ND filter changes stepwise.

12. A device according to claim 10, wherein said darkness distribution is formed, so that a transmission rate of said ND filter changes gradually.

13. A device according to claim 8, wherein said darkness distribution is formed, so that a transmission rate of said ND filter changes stepwise.

14. A device according to claim 8, wherein said darkness distribution is formed, so that a transmission rate of said ND filter changes gradually.

15. An aperture device in which a ND filter is attached to an aperture blade,

said ND filter being arranged by a method comprising the steps of:

preparing an original having a darkness distribution having a predetermined relationship with a darkness distribution for providing a ND filtering function;

exposing a film with light representing said darkness distribution of said original;

developing said exposed film; and

cutting said developed film in a form of said ND filter, said cutting step including the step of obtaining a plurality of said ND filters having the same density distribution,

wherein a width of said ND filter is decreased in a direction in which a darkness is increased.

16. A device according to claim 15, wherein variable-darkness paper sheets having different reflectances are used for preparing said original.

17. A device according to claim 15, wherein a plurality of lines of darkness distribution regions are formed on said original, a plurality of lines of darkness distribution regions are also formed on said developed film, and a large number of ND filters are obtained by cutting said film in units of lines of said plurality of lines of darkness distribution regions.

18. An aperture device according to claim 15, wherein a diazo film is used as said film.

19. An aperture device according to claim 15, wherein said film comprises a base having a transmission rate of not less than 80%, and an anti-halation layer.

20. An aperture device in which a ND filter is attached to an aperture blade,

said ND filter being arranged by a method comprising the steps of:

preparing an original having a darkness distribution having a predetermined relationship with a darkness distribution for providing a ND filtering function;

exposing a film with light representing said darkness distribution of said original;

developing said exposed film; and

cutting said developed film in a form of said ND filter, said cutting step including the step of obtaining a plurality of said ND filters having the same density distribution,

wherein said darkness distribution is formed so that a transmission rate of said ND filter changes stepwise.

21. A device according to claim 20, wherein variable-darkness paper sheets having different reflectances are used for preparing said original.

22. A device according to claim 20, wherein a plurality of lines of darkness distribution regions are formed on said original, a plurality of lines of darkness distribution regions are also formed on said developed film, and a large number of ND filters are obtained by cutting said film in units of lines of said plurality of lines of darkness distribution regions.

23. An aperture device according to claim 20, wherein a diazo film is used as said film.

24. An aperture device according to claim 20, wherein said film comprises a base having a transmission rate of not less than 80%, and an anti-halation layer.

25. An aperture device in which a ND filter is attached to an aperture blade,

said ND filter being arranged by a method comprising the steps of:

preparing an original having a darkness distribution having a predetermined relationship with a darkness distribution for providing a ND filtering function;

exposing a film with light representing said darkness distribution of said original;

developing said exposed film; and

cutting said developed film in a form of said ND filter, said cutting step including the step of obtaining a plurality of said ND filters having the same density distribution,

wherein said darkness distribution is formed so that a transmission rate of said ND filter changes gradually.

26. A device according to claim 25, wherein variable-darkness paper sheets having different reflectances are used for preparing said original.

27. A device according to claim 25, wherein a plurality of lines of darkness distribution regions are formed on said original, a plurality of lines of darkness distribution regions are also formed on said developed film, and a large number of ND filters are obtained by cutting said film in units of lines of said plurality of lines of darkness distribution regions.

28. A device according to claim 27, wherein said darkness distribution is formed so that a transmission rate of said ND filter changes gradually.

29. An aperture device according to claim 25, wherein a diazo film is used as said film.

30. An aperture device according to claim 25, wherein said film comprises a base having a transmission rate of not less than 80%, and an anti-halation layer.

31. An aperture device in which a ND filter is attached to an aperture blade,

said ND filter being arranged by a method comprising the steps of:

preparing an original having a darkness distribution having a predetermined relationship with a darkness distribution for providing a ND filtering function;

photographing said original by a camera to expose micro-copy film;

developing said exposed film; and

cutting said developed film in a form of said ND filter,

wherein a width of said ND filter is decreased in a direction in which a darkness is increased.

32. A device according to claim 31, wherein variable-darkness paper sheets having different reflectances are used for preparing said original.

33. An aperture device in which a ND filter is attached to an aperture blade,

said ND filter being arranged by a method comprising the steps of:

preparing an original having a darkness distribution having a predetermined relationship with a darkness distribution for providing a ND filtering function;

photographing said original by a camera to expose a micro-copy film;

developing said exposed film; and

cutting said developed film in a form of said ND filter,

wherein a plurality of lines of darkness distribution regions are formed on said original, a plurality of lines of darkness distribution regions are also formed on said developed film, and a large number of ND filters are obtained by cutting said film in units of lines of said plurality of lines of darkness distribution regions.

34. A device according to claim 33, wherein variable-darkness paper sheets having different reflectances are used for preparing said original.

35. An aperture device in which a ND filter is attached to an aperture blade,

said ND filter being arranged by a method comprising the steps of:

preparing an original having a darkness distribution having a predetermined relationship with a darkness distribution for providing a ND filtering function;

photographing said original by a camera to expose a micro-copy film;

developing said exposed film; and

cutting said developed film in a form of said ND filter,

wherein said darkness distribution is formed, so that a transmission rate of said ND filter changes stepwise.

36. A device according to claim 35, wherein variable-darkness paper sheets having different reflectances are used for preparing said original.

37. An aperture device in which a ND filter is attached to an aperture blade,

said ND filter being arranged by a method comprising the steps of:

preparing an original having a darkness distribution having a predetermined relationship with a darkness distribution for providing a ND filtering function;

photographing said original by a camera to expose a micro-copy film;

developing said exposed film; and

cutting said developed film in a form of said ND filter,

wherein said darkness distribution is formed, so that a transmission rate of said ND filter changes gradually.

38. A device according to claim 37, wherein variable-darkness paper sheets having different reflectances are used for preparing said original.