Illuminating lens designed by extrinsic differential geometry

• US 6,273,596 B1
• Filed: 05/20/1999
• Issued: 08/14/2001
• Est. Priority Date: 09/23/1997
• Status: Expired due to Fees

• Current Assignee: Teledyne Lighting & Display Products, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: Teledyne Lighting & Display Products, Inc. (Teledyne Technologies Incorporated)
• Inventors: Parkyn, William A. Jr.
• Primary Examiner(s): Husar, Stephen
• Assistant Examiner(s): WARD, JOHN A
• Application Number:
  US09/315,262
• Time in Patent Office: 817 Days
• Field of Search: 362/332, 362/522, 362/290, 362/291, 362/292, 362/339, 362/340, 362/342, 362/354
• US Class Current: 362/522
• CPC Class Codes: F21S 43/14 Light emitting diodes [LED]
• CPC Class Codes: F21V 33/006 General building constructions or finishing work for buildings, e.g. roofs, gutters, stairs or floors; Garden equipment; Sunshades or parasols
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21W 2107/20 for water vehicles
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 27/0012 Optical design, e.g. procedures, algorithms, optimisation routines
• CPC Class Codes: G02B 3/02 with non-spherical faces G02B3/10 takes precedence

Abstract

A grid defining illumination cells having areas to pass light from a source for use in generation of a lines, wherein the grid is defined by first lines extending about one axis defined by the source, and second lines emanating from the axis to intersect first lines, each cell having four edges defined by successive of first lines and successive of second lines, the cells having one of the following:

i) equal areas

ii) areas that increase in direction away from the source.

Claims

1. First and second virtual grids each defining illumination cells having areas to pass light from a source, for use in mathematical generation of a lens shape, comprising

a) said virtual grids being spaced apart along an axis, both grids being dome shaped to bulge in the same generally axial direction, each grid defined by first lines and second lines that intersect said first lines,

b) each cell having four edges defined by successive of said first lines and successive of said second lines, each cell having four corners, each corner defined by an intersection of a first said line and a second said line,

c) the respective cells of the first grid having light flux passing one to one correspondence with the respective cells of the second grid all cells of at least one grid having substantially equal areas.

2. The grids of claim 1 wherein said lines define a series of increasingly larger rectangles, certain of said second lines intersecting corners of the rectangles, and of cells, at each grid.

3. The grids of claim 1 wherein for each grid said first lines define circular latitude lines, and said second lines define longitude lines, with respect to said axis.

4. The grids of claim 3 wherein said latitude lines extend about said axis, the spacing between successive latitude lines increasing in directions extending along said longitude lines.

5. The grids of claim 1 wherein the first grid is substantially smaller than the second grid whereby they are spaced apart to define a lens zone therebetween.

6. The lens of claim 1 wherein the lens has a conical base.

7. The lens of claim 6 including a light source coupled with said base.

17. A lens formed by use of two grids as defined in claim 1, the lens located between the grids, one grid located at the light output side of the lens being larger than the other grid located at the light input side of the lens.

18. Multiple lenses as defined in claim 17, and arrayed generally in rows and columns.

8. In combination, a lens having a conical base and diverging from the base toward a light projecting surface, and a light pipe coupled to said base, said lens having overall length and overall width, said length being greater than said width, said lens having an associated grid defining light flux passing cells having substantially equal areas.

9. The combination of claim 8 wherein said light projecting surface has a center region, and stepped ridges diverging away from said center region.

10. The combination of claim 9 wherein said surface has concavely dished zones located between said ridges.

11. The combination of claim 9 wherein said surface has steps between the ridges.

12. A grid defining illumination cells to distribute light from a source, for use in generation of a lens, said grid having an associated pattern of rectangles os successively larger sized, successively larger rectangles extending about said source, all rectangles having coincident centers at said source, said grid having an associated pattern of radial lines emanating from said source to intersect said rectangles at corners thereof and along lines extending between said corners, thereby to define said cells, said grid defining at least one asymmetric dome, said cells having substantially equal flux passing areas.

13. The grid of claim 12 wherein all cells have the same area.

14. The grid of claim 12 wherein successive cells have increasing area.

15. The method of prescribing the design of a lens having a light entrance surface, an interior, and alight exit surface, the steps that include:

a) on the Gaussian sphere of directions of the output beam exiting the surface of the lens, in accordance with the prescribed output pattern, establish a first grid of equal-flux zones of solid angle;

b) on a portion of the Gaussian sphere of directions of the light emitted from the source into the interior of the lens, establish a second grid with the same number of equal-flux zones of solid angles as the first grid, with a coordinate-system topology congruent with that of the first grid, such that the zones of the second grid are in one-to-one correspondence with the zones of the first grid, with the flux of each zone in proportion to its corresponding zone of the first grid, according to the local transmittance of the lens, with either of both of the grids being rotationally non-symmetric;

the flux zones of at least one of said grids defining cells having substantially equal flux passing areas;

c) by correspondence define a flux-redistributing directional mapping function from the first Gaussian sphere to the second Gaussian sphere, whereby any light ray from the source can be assigned a direction in the output beam, according to the zone of the second grid into which the ray falls, so that the redirected ray falls in the corresponding zone of the first grid;

d) establish one or more lens surfaces to redirect the source rays to the output rays, using the vector laws of refraction or reflection to derive a distribution of normal vectors for each surface; and

e) from the distributions of normal vectors, successively generate each lens surface, beginning with that nearest source and progressing outwards, whereby from an initial starting point, calculate the surface coordinates of each surface of the lens by contact-integrating the distribution of surface normal vectors, along an initial strip that follows one principal curvature of the surface and then, by successive contact-integrations, orthogonally outwards from the initial strip, of the grid of surface normals, generate adjacent characteristic geodesic strips outward to the boundary of the second grid.

16. The method of claim 15, including:

g) to ensure that the surface of the lens possesses the surface normals necessary for it to transform the light from the source into an output beam substantially fulfilling the prescription, perform the successive integrations of adjacent characteristic geodesic strips so as to fulfill the integrability condition dictating equality of the crossed second derivatives of the surface of the lens;

h) and determine the overall size of the lens relative to the size of the light source by selecting the distance of the initial point from the source to keep the blurring of the output beam below a level defined by the angular resolution of the prescription.

19. A grid defining illumination cells having substantially equal light flux passing areas to pass light from a source, for using in generation of a lens, comprising:

a) said grid defined by first lines defining a series of rectangles extending about an axis defined by the source and second lines emanating from said axis to intersect said first lines, successive rectangles being larger in directions away from said axis, said rectangles having corners intersected by certain of said second lines,

b) each cell having four edges defined by successive of said first lines and successive of said second lines, each cell having four corners, each corner defined by an intersection of a first said line and a second said line.