Granted Patent B2

US 6,923,559 · App. 10/427,337 · Granted Aug 2, 2005

Abstract

Claims (24)

1. A method for designing a light guide, comprising:

a) determining a generated radiation pattern for a source, said source being considered an approximate point source;

b) setting a largest dot size of said light guide;

c) setting a smallest dot size of said light guide proximate to said source;

d) setting an array of monotonically increasing dot sizes intermediate in size and location between said smallest and said largest dot sizes along a radius of said approximate point source; and

e) verifying that all dots in said array increase monotonically in size with distance from said source.

2. The method of claim 1 comprising setting said largest dot size proximate to the perimeter of said light guide.

3. The method of claim 1 comprising setting said monotonically increasing dot sizes between said smallest and said largest dot sizes along orthogonal rectangular axes.

4. The method of claim 1 wherein said approximate point source generates a radiation pattern having a primary directionality with intensity decreasing radially from said primary directionality of said approximate point source.

5. The method of claim 4 wherein said source comprises at least one light emitting diode (LED).

6. The method of claim 1 further comprising:

f) terminating said method of designing when all dots in said array are verified to increase monotonically in size with distance from said source, and otherwise repeating b) through e) of said method.

7. An apparatus for illumination, comprising:

a light source operable to generate a directional radiation pattern, said directional radiation pattern having maximum intensity along a first radius directed from said source at a first angle and lower relative intensity along radii from said source angularly offset relative to said first radius;

a light guide adjacent said light source, said light guide operable to be illuminated by said directional radiation pattern, said light guide comprising an array of varying sized dots operable to diffusely reflect said directional illuminating radiation pattern, said dot array comprising monotonically increasing dot sizes intermediate between said smallest and said largest dot sizes, said dot array pattern determined by said directional radiation pattern such that said smallest dot size is proximate to said light source and said largest dot size is distal from said light source.

8. The apparatus of claim 7 wherein said light source comprises at least one light emitting diode (LED).

9. The apparatus of claim 7 wherein said largest dot size is proximate to the perimeter of said light guide.

10. The apparatus of claim 7 wherein said monotonically increasing dot sizes between said smallest and said largest dot size are located along radii centered at said light source.

11. The apparatus of claim 7 wherein said monotonically increasing dot sizes between said smallest and said largest dot size are located along orthogonal rectangular axes.

12. The apparatus of claim 7 wherein said dots comprise a diffusely reflective coating material.

13. The apparatus of claim 12 wherein said diffusely reflective coating material comprises a polymer-based white ink.

14. The apparatus of claim 7 wherein said dots of varying size have shapes selected from the group consisting of cylindrical, hemispherical, polygonal, or pyramidal shapes.

15. The apparatus of claim 7 wherein said light guide is formed by injection molding.

16. The apparatus of claim 15 wherein said dots of varying size are injection molded integrally with said light guide.

Assignments (17)