Light directing optical structure

• US 5,555,329 A
• Filed: 01/23/1995
• Issued: 09/10/1996
• Est. Priority Date: 11/05/1993
• Status: Expired due to Term

• Current Assignee: Alliedsignal Inc.
• Original Assignee: Alliedsignals Incorporated
• Inventors: Kuper, Jerry, Segal, Leon, Beeson, Karl W., Zimmerman, Scott M.
• Primary Examiner(s): Ullah, Akm E.
• Application Number:
  US08/376,709
• Time in Patent Office: 596 Days
• Field of Search: 359/484, 359/281, 359/487, 359/834, 359/634, 359/636, 359/850, 359/630, 356/350, 356/399, 356/154, 250/227.21, 250/231.14, 250/231.13, 385/31, 385/34, 385/36, 385/37, 385/39, 385/120, 385/121, 385/147
• US Class Current: 385/36
• CPC Class Codes: F21V 5/02 of prismatic shape F21V5/04 takes precedence
• CPC Class Codes: F21Y 2103/00 Elongate light sources, e.g. fluorescent tubes
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses

Abstract

A light directing optical structure is formed of a light waveguide preferably made of clear plastic; attached to or formed with the waveguide are a multiplicity of prisms. Each prism, due to its index of refraction, provides an aperature where light may escape the waveguide rather than remain confined due to total internal refraction. The light escaping the waveguide is reflected from a side face of the prism, and redirected in a desired direction. The propagation paths within the waveguide are such that the light emerging through the aperature is of only a fairly closely constrained range of angles; as a result the light that is redirected by the side face of the prism is of a similarly constrained range of angles.

The geometry of the prism can be optimized to direct the output light perpendicular to the plane, or at a desired angle other than perpendicular. The optical structure can receive a light input along an edge, or along several edges, and its output beam is perpendicular to the structure or at some desired angle other than perpendicular. There is no restriction on the distribution and uniformity of the light input, yet the ouput is a directed and intensity controlled light source. Configurations are disclosed adapting the structure to several different possible light distribution patterns.

Claims

1. An apparatus for directing light in a desired direction, the apparatus comprising:

a) a first waveguide having a first edge and a second edge opposed thereto, said first waveguide having an index of refraction higher than that of its surroundings;

b) a quadrilateral second waveguide, said second waveguide having an index of refraction higher than that of its surroundings and having first, second, third, and fourth edges, the first edge of the second waveguide optically coupled with and sized to fit the first edge of the first waveguide;

the fourth edge opposed to the first edge of the second waveguide, said fourth edge defining an input face;

said second and third edges connecting said first and fourth edges, said second and third edges each defining respective acute angles with said first edge; and

c) a multiplicity of prisms optically coupled with a face of said planar first waveguide.

2. The apparatus of claim 1 further comprising a parabolically focused light source optically coupled to said input face.

3. The apparatus of claim 1 wherein the first and second waveguides are integrally formed.

4. The apparatus of claim 1 wherein the first waveguide is substantially rectangular.

5. A light directing apparatus comprising:

a) a first waveguide having a first edge and a second edge opposed thereto, said first waveguide having an index of refraction higher than that of its surroundings;

b) a substantially trapezoidal first prism, said first prism having an index of refraction higher than that of its surroundings, the trapezoidal cross section of the first prism defining first and second parallel sides and third and fourth sides, the prism face containing said first side optically coupled with and sized to fit the first edge of the waveguide;

the prism face containing said second side being larger in area than said prism face containing said first side and defining a first input face;

said second and third sides each defining respective acute angles with said second side; and

c) a multiplicity of second prisms optically coupled with a face of said planar first waveguide.

6. The apparatus of claim 5 further comprising a first extended light source optically coupled with the first input face.

7. The apparatus of claim 6 further comprising a first involute reflector surrounding said first light source and mechanically coupled with said first input face thereby defining a first enclosure about said first light source.

8. The apparatus of claim 5 wherein the waveguide and first prism are integrally formed.

9. The apparatus of claim 5 further comprising a substantially trapezoidal third prism, said third prism having an index of refraction higher than that of its surroundings, the trapezoidal cross section of the third prism defining first and second parallel sides and third and fourth sides, the prism face containing said first side optically coupled with and sized to fit the second edge of the waveguide;

the prism face containing said second side being larger in area than said prism face containing said first side and defining a second input face;

said second and third sides each defining respective acute angles with said second side.

10. The apparatus of claim 9 further comprising a second extended light source optically coupled with the second input face.

11. The apparatus of claim 10 further comprising a second involute reflector surrounding said second light source and mechanically coupled with said second input face thereby defining a second enclosure about said second light source.

12. The apparatus of claim 5 wherein the waveguide and second prism are integrally formed.

13. An apparatus for directing light in a desired direction, the apparatus comprising:

a) a waveguide having an edge for coupling to a light source, the wave guide having an index of refraction r₁, the surroundings of the waveguide having an index of refraction n_o, the ratio of n_o to n₁ defining a ratio r₁ ;

the waveguide having first and second sides;

b) a multiplicity of prisms each having a respective index of refraction n₂, the ratio of n₀ to n₂ defining a ratio r₂, the ratio r₂ approximately equal to r₁, each prism having at least first, second, and third faces; and

c) the first, second, and third prism faces characterized in that the first face is optically coupled to said waveguide;

the second face is substantially planar, and defines a tilt angle with respect to said first side, the third face of each prism having a portion tangent to a plane substantially perpendicular to the desired light output direction.

14. The apparatus of claim 13 wherein the first and second sides of the waveguide are parallel.

15. The apparatus of claim 13 wherein the waveguide and prisms are integrally formed of the same material.

16. The apparatus of claim 13 wherein the waveguide and prisms are formed separately and attached so as to be optically coupled.

17. The apparatus of claim 13 wherein the desired light output direction is substantially perpendicular to the first side of the waveguide.

18. The apparatus of claim 13 wherein the second face of each prism is planar.

19. The apparatus of claim 13 wherein the third face of each prism is planar.

20. The apparatus of claim 13 wherein the third face of each prism is a convex lens.

21. The apparatus of claim 13 wherein the third face of each prism is a concave lens.

22. The apparatus of claim 13 wherein the third face of each prism is an aspheric lens.

23. An apparatus for directing light in a desired direction, the apparatus comprising:

a) a first waveguide having a first edge and a second edge opposed thereto, said first waveguide having an index of refraction higher than that of its surroundings;

b) a second waveguide optically coupled to the first edge; and

c) a multiplicity of prisms optically coupled with a face of said planar first waveguide.

24. The apparatus of claim 23 further comprising a reflecting sheet at the second edge of the first waveguide disposed to reflect light within the first waveguide.

25. The apparatus of claim 23 further comprising a light source optically coupled with said second waveguide and remote from said first waveguide.

26. The apparatus of claim 23 wherein the second waveguide is a bundle of fiber optic cables.