Cone shaped Fresnel reflector

• US 4,789,921 A
• Filed: 02/20/1987
• Issued: 12/06/1988
• Est. Priority Date: 02/20/1987
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Aho, Kenneth A.
• Primary Examiner(s): Hart, Douglas
• Application Number:
  US07/016,858
• Time in Patent Office: 655 Days
• Field of Search: 362/301, 362/341, 362/348, 362/349, 350/613, 350/452
• US Class Current: 362/348
• CPC Class Codes: F21S 41/37 characterised by their material, surface treatment or coatings
• CPC Class Codes: F21S 43/30 characterised by reflectors
• CPC Class Codes: F21S 43/33 characterised by their material, surface treatment or coatings
• CPC Class Codes: F21V 7/09 with a combination of different curvatures
• CPC Class Codes: F21V 7/22 characterised by materials, surface treatments or coatings, e.g. dichroic reflectors

Abstract

A Fresnel-type reflector having the physical shape of a cone. In a preferred embodiment, the reflector is made by forming a reflective coating on a structured surface of a thin flexible film and forming the film into the shape of a cone. The structures on the surface are designed to cause the reflector to imitate the optical properties of a parabolic reflector when the reflector of the invention is formed into the shape of a cone.

Claims

1. A reflector apparatus comprising a reflector having a major surface, said major surface being reflective and having coaxial Fresnel-type structures thereon, said reflector being formed into the shape of a cone having a base.

2. The apparatus of claim 1, wherein said base is circular.

3. The apparatus of claim 1, wherein said base is rectangular.

4. The apparatus of claim 1, wherein said Fresnel-type structures are disposed in parallel planes and one facet of each structure causes said reflector to have the optical properties of a parabolic reflector.

5. The apparatus of claim 1, wherein said cone is a truncated cone.

6. The apparatus of claim 1, wherein said reflector is made of a flexible material.

7. The apparatus of claim 6, further comprising conical support means for supporting said reflector.

8. The apparatus of claim 7, wherein said reflector is bonded to said conical support means by an adhesive.

9. The apparatus of claim 8, wherein said Fresnel-type structures cause said reflector to have the optical properties of a parabolic reflector.

10. The apparatus of claim 9, wherein said cone is a truncated cone.

11. The apparatus of claim 7, wherein said conical support means comprises retaining means for holding said reflector.

12. The apparatus of claim 11, wherein said Fresnel-type structures cause said reflector to have the optical properties of a parabolic reflector.

13. The apparatus of claim 12, wherein said cone is a truncated cone.

14. The apparatus of claim 1, wherein said reflector is made of an optically transparent material and said major surface is coated with a reflecting material.

15. The apparatus of claim 14, wherein said Fresnel-type structures cause said reflector to have the optical properties of a parabolic reflector.

16. The apparatus of claim 14, wherein said reflector is made of a flexible material.

17. The apparatus of claim 16, further comprising conical support means for supporting said reflector.

18. The apparatus of claim 17, wherein said reflector is bonded to said conical support means by an adhesive.

19. The apparatus of claim 18, wherein said Fresnel-type structures cause said reflector to have the optical properties of a parabolic reflector.

20. The apparatus of claim 19, wherein said cone is a truncated cone.

21. The apparatus of claim 16, wherein said conical support means comprises retaining means for holding said reflector.

22. The apparatus of claim 21, wherein said Fresnel-type structures cause said reflector to have the optical properties of a parabolic reflector.

23. The apparatus of claim 22, wherein said cone is a truncated cone.

24. A thin sheet of a flexible material having a major surface, said major surface being reflective and having concentric, Fresnel-type structures thereon, said sheet having a periphery which includes first and second edges radial to said Fresnel-type structures such that, when said edges are brought together, the sheet is formed into the shape of a cone having a base.

25. The sheet of claim 24 wherein said base is round.

26. The sheet of claim 24 wherein said base is square.

27. The sheet of claim 24 wherein said Fresnel-type structures cause said sheet to have the optical properties of a parabolic reflector when said radial edges are brought together.

28. The sheet of claim 24 wherein said cone is a truncated cone.

29. The sheet of claim 28 wherein said Fresnel-type structures cause said sheet to have the optical properties of a parabolic reflector when said radial edges are brought together.

30. The sheet of claim 24 wherein said sheet is optically transparent and said major surface is coated with a reflecting material.

31. The sheet of claim 30 wherein said cone is a truncated cone.

32. The sheet of claim 31 wherein said Fresnel-type structures cause said sheet to have the optical properties of a parabolic reflector when said radial edges are brought together.