Illumination device and photographing apparatus having the same

• US 6,807,369 B1
• Filed: 04/13/2000
• Issued: 10/19/2004
• Est. Priority Date: 04/15/1999
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tenmyo, Yoshiharu
• Primary Examiner(s): PERKEY, WILLIAM B
• Application Number:
  US09/549,235
• Time in Patent Office: 1,650 Days
• Field of Search: 396/61, 396/62, 396/175, 362/16-18, 362/277, 362/308, 362/327, 362/328, 362/309
• US Class Current: 396/175
• CPC Class Codes: F21V 13/04 the elements being reflectors and refractors for vehicle rear lights F21S43/40
• CPC Class Codes: F21V 5/045 the lens having discontinuous faces, e.g. Fresnel lenses
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21Y 2103/00 Elongate light sources, e.g. fluorescent tubes
• CPC Class Codes: G03B 15/05 Combinations of cameras with electronic flash apparatus; Electronic flash units
• CPC Class Codes: G03B 2215/0503 Built-in units
• CPC Class Codes: G03B 2215/0578 Flashtube mounting
• CPC Class Codes: G03B 2215/0582 Reflectors
• CPC Class Codes: G03B 2215/0592 installed in front of light emitter

Abstract

An illumination device includes a flash discharge tube, an optical prism having a total-reflection surface for totally reflecting at least a part of incident light, light emitted from the flash discharge tube being made incident on the optical prism, and an optical panel, light having exited from the optical prism being made incident on the optical panel, wherein the illumination device varies a state of illumination light by varying a positional relationship between the optical prism and the optical panel.

Claims

1. An illumination device comprising:

a light source;

a first optical member having a total-reflection surface for totally reflecting at least a part of incident light, light emitted from said light source being made incident on said first optical member; and

a second optical member, light having exited from said first optical member being made incident on said second optical member,

wherein said illumination device varies a state of illumination light by varying a positional relationship between said first optical member and said second optical member.

2. An illumination device according to claim 1, wherein said first optical member further has a first entrance surface, a second entrance surface and an exit surface, and light incident on said first entrance surface advances directly to said exit surface and light incident on said second entrance surface advances to said exit surface through said total-reflection surface.

3. An illumination device according to claim 2, wherein said second entrance surface is a plane surface, and the following condition is satisfied:

4. An illumination device according to claim 1, wherein light emitted from the center of said light source and advancing to an exit surface of said first optical member is a parallel beam.

5. An illumination device according to claim 1, wherein an exit surface of said first optical member is provided with a pattern having a predetermined refracting action, and said second optical member is provided with a pattern for substantially offsetting the refracting action of the exit surface of said first optical member at a predetermined position.

6. An illumination device according to claim 5, wherein said light source has a cylindrical shape extending in a predetermined direction, and the exit surface of said first optical member has a refracting action in a direction perpendicular to the predetermined direction.

7. An illumination device according to claim 6, wherein the exit surface of said first optical member is provided with a pattern in which a plurality of cylindrical lenses each having a refracting action within a plane perpendicular to the predetermined direction are arranged in a direction perpendicular to the predetermined direction, and wherein each of said plurality of cylindrical lenses has such a shape as to convert a parallel light beam into a plurality of convergent rays.

8. An illumination device according to claim 7, wherein the following conditions are satisfied:

9. An illumination device according to claim 6, wherein the exit surface of said first optical member is provided with a pattern in which a plurality of cylindrical lenses each having a refracting action within a plane perpendicular to the predetermined direction are arranged in a direction perpendicular to the predetermined direction, and wherein each of said plurality of cylindrical lenses has such a shape as to proportionally distribute a parallel light beam at a predetermined rate according to an incidence position thereof.

10. An illumination device according to claim 5, wherein the exit surface of said first optical member has a refracting action varying according to a position thereof.

11. An illumination device according to claim 1, wherein an exit surface of said first optical member is provided with a pattern having a predetermined refracting action, and said second optical member is provided with a pattern having such a shape as to substantially fit in with the exit surface of said first optical member.

12. An illumination device according to claim 11, wherein said light source has a cylindrical shape extending in a predetermined direction, and the exit surface of said first optical member has a refracting action in a direction perpendicular to the predetermined direction.

13. An illumination device according to claim 12, wherein the exit surface of said first optical member is provided with a pattern in which a plurality of cylindrical lenses each having a refracting action within a plane perpendicular to the predetermined direction are arranged in a direction perpendicular to the predetermined direction, and wherein each of said plurality of cylindrical lenses has such a shape as to convert a parallel light beam into a plurality of convergent rays.

14. An illumination device according to claim 13, wherein the following conditions are satisfied:

15. An illumination device according to claim 12, wherein the exit surface of said first optical member is provided with a pattern in which a plurality of cylindrical lenses each having a refracting action within a plane perpendicular to the predetermined direction are arranged in a direction perpendicular to the predetermined direction, and wherein each of said plurality of cylindrical lenses has such a shape as to proportionally distribute a parallel light beam at a predetermined rate according to an incidence position thereof.

16. An illumination device according to claim 11, wherein the exit surface of said first optical member has a refracting action varying according to a position thereof.

17. An illumination device according to claim 1, wherein said second optical member is provided, on at least a part of en exit surface thereof, with a Fresnel lens.

18. An illumination device according to claim 1, further comprising:

a reflection member disposed on a side of said light source opposite to said first optical member, said reflection member having a reflecting surface in the shape of a circle in a predetermined section having a central point thereof set at the center of said light source.

19. A photographing apparatus comprising:

a photographic optical system; and

an illumination device according to claim 1,

wherein said photographing apparatus varies a state of illumination light emitted from said illumination device, according to a state of said photographic optical system.