Color mixing optics for LED lighting

Abstract

Color mixing optics for a multi-color LED lamp comprise an outer reflector having a paraboloidal surface of revolution and a total inner reflection (TIR) lens having an outer contour with a paraboloidal surface of revolution. The outer reflector and the TIR lens are centered around a common center axis. A common focal point of the outer reflector and the TIR lens is provided for placing a LED assembly. Such LED lamps produce uniform color throughout the entire light beam while the outer dimensions are such that the optics fit into conventional lamp housings.

The invention claimed is: 
     
       1. A color mixing optics for LED lighting comprising:
 an outer reflector having a paraboloidal surface of revolution centered around a center axis and defining a reflector focal point;   a total inner reflection lens having a concave light entrance surface with a radius of curvature to enable light to enter the total inner reflection lens at a right angle, and the total inner reflection lens having an outer contour with a paraboloidal surface of revolution centered around the center axis and defining a total inner reflection lens focal point, wherein   the outer contour with a paraboloidal surface of revolution of the total inner reflection lens is held a spaced distance within the outer reflector; and   wherein the reflector focal point is in close proximity to the total inner reflection lens focal point.   
     
     
       2. The color mixing optics according to  claim 1 , wherein the total inner reflection lens has a concave light entrance surface oriented towards the total inner reflection lens focal point. 
     
     
       3. The color mixing optics according to  claim 2 , wherein the concave light entrance surface has a spherical shape. 
     
     
       4. The color mixing optics according to  claim 1 , wherein the total inner reflection lens is positioned within the outer reflector. 
     
     
       5. The color mixing optics according to  claim 1 , wherein the total inner reflection lens is attached to a cover located on the outer reflector. 
     
     
       6. The color mixing optics according to  claim 1 , wherein the total inner reflection lens is part of a cover located on the outer reflector. 
     
     
       7. The color mixing optics of  claim 1 , wherein a radius of an upper aperture of the total inner reflection lens is substantially equal to a radius of a lower aperture of the outer reflector. 
     
     
       8. The color mixing optics of  claim 1 , wherein a depth of the total inner reflection lens extends to a point where the total inner reflection lens parabola intersects a line extending between a source point on the center axis and an edge point of the outer reflector. 
     
     
       9. A multi-color LED lamp comprising:
 an outer reflector having a paraboloidal surface of revolution centered around a center axis and defining a reflector focal point;   a total inner reflection lens having a concave light entrance surface with a radius of curvature to enable light to enter the total inner reflection lens at a right angle, and the total inner reflection lens having an outer contour with a paraboloidal surface of revolution centered around the center axis and defining a total inner reflection lens focal point; wherein the outer contour with a paraboloidal surface of revolution of the total inner reflection lens is held a spaced distance within the outer reflector; wherein the reflector focal point is in close proximity to the total inner reflection lens focal point; and an LED assembly comprising a plurality of LEDs and being mounted in close proximity to the reflector focal point and the total inner reflection lens focal point.   
     
     
       10. The multi-color LED lamp according to  claim 9 , wherein the LED assembly or parts thereof are covered by a LED lens. 
     
     
       11. The multi-color LED lamp according to  claim 10 , wherein the LED lens has a spherical shape. 
     
     
       12. The multi-color LED lamp according to  claim 9 , wherein the LED assembly has a LED surface plane which is mounted in close proximity to the total inner reflection lens focal point. 
     
     
       13. The multi-color LED lamp according to  claim 9 , wherein the center of the LED assembly is mounted in close proximity to the center axis. 
     
     
       14. The multi-color LED lamp according to  claim 9 , wherein the LED assembly is mounted on a base. 
     
     
       15. The multi-color LED lamp according to  claim 9 , wherein a housing is provided surrounding the outer reflector. 
     
     
       16. The multi-color LED lamp according to  claim 9 , wherein the total inner reflection lens is attached to a cover located on the housing. 
     
     
       17. The multi-color LED lamp according to  claim 9 , wherein the total inner reflection lens is part of a cover located on the housing. 
     
     
       18. A method for generating a mixed beam of light by generating light at multiple wavelengths by a LED assembly comprising a plurality of LEDs and:
 reflecting a first portion of said light by an outer reflector having a paraboloidal surface of revolution centered around a center axis and defining a reflector focal point;   while reflecting a second portion of said light forwarded from the plurality of LEDs at an angle relative to the center axis that is less than the first portion of said light forwarded from the plurality of LEDs, wherein the second portion is reflected from a total inner reflection lens having a concave light entrance surface with a radius of curvature to enable light to enter the total inner reflection lens at a right angle, and the total inner reflection lens having an outer contour with a paraboloidal surface of revolution centered around the center axis and defining a total inner reflection lens focal point; and   wherein the reflector focal point is in close proximity to the total inner reflection lens focal point.   
     
     
       19. The method as recited in  claim 18 , wherein said reflecting consists of avoiding any refraction. 
     
     
       20. A lamp comprising:
 a hollow parabolic reflective surface disposed about a central axis;   a transparent cover member disposed coaxially along the central axis, proximate a first end of the hollow parabolic reflective surface; and   a total internal reflection (TIR) lens having an external surface, the TIR lens disposed coaxially along the central axis inside the hollow parabolic reflective surface;   wherein an exit surface of the TIR lens is disposed proximate the transparent cover;   wherein the transparent cover member spaces the external surface of the TIR lens apart from the hollow parabolic reflective surface to provide a gab between the TIR lens and the reflective surface;   wherein the TIR lens and the hollow parabolic reflective surface have a common focal point; and   wherein the lamp is configured to accommodate a light-emitting diode (LED) light source disposed at the common focal point such that light emitted by the LED light source either: enters the TIR lens at a normal angle and passes through the TIR lens; or reflects from the hollow parabolic reflective surface without passing through the TIR lens.    
     
     
       21. The lamp of  claim 20  wherein the TIR lens comprises a conic frustum.  
     
     
       22. The lamp of  claim 20  wherein the TIR lens comprises a paraboloidic frustum.  
     
     
       23. The lamp of  claim 22  wherein an entrance surface of the TIR lens comprises a concave entrance surface and the exit surface of the TIR lens comprises a planar exit surface.  
     
     
       24. The lamp of  claim 23 :
 wherein the hollow parabolic reflective surface includes:
 a lower aperture; and 
 an upper aperture: and 
   wherein a radius of the exit surface of the TIR lens is approximately equal to a radius of the lower aperture of the hollow parabolic reflective surface.    
     
     
       25. The lamp of  claim 24 , wherein the transparent cover member is affixed to the exit surface of the TIR lens.  
     
     
       26. The lamp of  claim 24  wherein the transparent cover is formed integral with the TIR lens.  
     
     
       27. The lamp of  claim 23  wherein the LED light source includes:
 a light-emitting diode (LED) assembly having a central axis disposed coaxially with the TIR lens and the hollow parabolic reflective surface, the LED assembly including:
 a plurality of LEDs distributed as a matrix about the central axis; and 
 a hemispherical lens disposed about the central axis, the hemispherical lens covering the plurality of LEDs, the hemispherical lens spaced apart from the concave entrance surface of the TIR lens by an air gab.  
 
 
     
     
       28. The lamp of  claim 27  wherein the LED assembly comprises a planar LED array having a center point disposed at the common focal point of the TIR lens and the hollow parabolic reflective surface.  
     
     
       29. The lamp of  claim 28  wherein the LED assembly further comprises a photodiode disposed proximate the plurality of LEDs, the photodiode positioned such that the hemispherical lens covers the photodiode.  
     
     
       30. The lamp of  claim 29  wherein the plurality of LEDs and the photodiode are mounted on a common printed circuit board.  
     
     
       31. The lamp of  claim 30  wherein the plurality of LEDs comprises a 2×2 matrix of LEDs consisting of:
 one red LED, one blue LED, one green LED, and one white LED.  
 
     
     
       32. A lamp comprising:
 a light-emitting diode (LED) array;   a reflector adjacent to the LED array to collimate a portion of light emitted by the LED array; and   a total internal reflection (TIR) lens coaxially disposed within the reflector, wherein the remaining portion of light emitted by the LED array enters the TIR lens without refraction and passes through the TIR lens, and wherein the TIR lens and the reflector have a common focal point.    
     
     
       33. The lamp of  claim 32 , further comprising a transparent cover engaging an upper aperture of the reflector and an upper aperture of the TIR lens.  
     
     
       34. The lamp of  claim 33 , wherein a radius of the upper aperture of the TIR lens is substantially equal to a radius of a lower aperture of the reflector.  
     
     
       35. The lamp of  claim 33 , wherein a depth of the TIR lens extending from the cover toward the LED array is less than a depth of the reflector extending from the cover to the lower aperture of the reflector.  
     
     
       36. The lamp of  claim 35 , wherein the depth of the TIR lens is sufficient to ensure the portion of light emitted by the LED array which does not pass through the TIR lens is collimated by the reflector.  
     
     
       37. The lamp of  claim 32 , wherein the LED array, the reflector, and the TIR lens are each aligned along a common central axis.  
     
     
       38. The lamp of  claim 32 , wherein the TIR lens has a concave light entrance.  
     
     
       39. The lamp of  claim 32 , wherein an interior surface of the reflector is parabolic reflective surface.