Extremely wide distribution light-emitting diode (LED) lens for thin direct-lit backlight
Disclosed lens designs enable uniform light distribution without hot spot, achieving wider transfer functions of light compared with traditional lenses, with a benefit of reducing the number of light sources needed and overall cost for direct-lit backlight device. A disclosed lens includes a beam shaping element on the top thereof and a backlight device incorporating the lens and the beam shaping element to eliminate a light hot spot produced by the backlight device and obtain a uniform light distribution at the illumination field. The disclosed lens is especially useful when extremely wider transfer function or extremely thin backlight is needed.
1. A system, comprising:
a lens configured to shape light emitted from a light-emitting diode to form shaped light; and
a beam-shaping element coupled to the lens and positioned to receive at least some of the shaped light,
the beam-shaping element including a pattern of reflective elements that are configured to reflect a first portion of the shaped light toward the lens,
the beam-shaping element allowing a second portion of the shaped light to propagate through the beam-shaping element and away from the lens through one or more spaces between adjacent reflective elements in the pattern.
2. The system of claim 1 , wherein the reflective elements are arranged in a substantially rectilinear pattern.
3. The system of claim 1 , wherein the reflective elements are arranged in an irregular pattern.
4. The system of claim 1 , wherein the reflective elements have a same size and a same shape.
5. The system of claim 1 , wherein the reflective elements include at least some substantially circular reflective dots.
6. The system of claim 1 , wherein the pattern of reflective elements is formed in a reflective coating positioned on a surface of the beam-shaping element.
7. The system of claim 6 , wherein the reflective coating includes an aluminum film.
8. The system of claim 1 , wherein the beam-shaping element is positioned and sized to receive only a portion of the shaped light from the lens.
9. The system of claim 1 , wherein the shaped light, at a plane of the beam-shaping element, extends over an area that is larger than an area of the beam-shaping element.
10. The system of claim 1 , wherein the beam-shaping element is positioned and sized to receive only a central portion of the shaped light from the lens.
11. The system of claim 1 , wherein:
the lens defines an optical axis; and
the beam-shaping element is centered on the optical axis.
12. The system of claim 1 , wherein:
the lens is radially symmetric about an optical axis; and
the beam-shaping element is radially symmetric and is centered on the optical axis.
13. The system of claim 1 , further comprising a plurality of protrusions that fasten the beam-shaping element to an exiting surface of the lens.
14. The system of claim 13 , wherein:
the exiting surface of the lens includes a concave central portion surrounded by a convex peripheral portion; and
the plurality of protrusions fasten the beam-shaping element to the convex peripheral portion of the exiting surface of the lens.
15. The system of claim 1 , further comprising a light-emitting diode configured to emit light towards the lens to form the shaped light.
16. A method, comprising:
producing light with a light-emitting diode;
shaping the light with a lens to form shaped light, the shaped light including a central portion and a peripheral portion surrounding the central portion;
reflecting, with a pattern of reflective elements positioned on a beam-shaping element that is coupled to the lens, at least some of the central portion of the shaped light toward the lens; and
transmitting, through one or more spaces between adjacent reflective elements in the pattern, at least some of the central portion of the shaped light through the beam-shaping element and away from the lens.
17. The method of claim 16 , wherein:
the produced light is rotationally symmetric about an optical axis; and
the lens, the shaped light, and the beam-shaping element are rotationally symmetric about the optical axis.
18. The method of claim 16 , further comprising:
directing the peripheral portion of the shaped light around the beam-shaping element, such that the peripheral portion of the shaped light does not strike the beam-shaping element.
19. A system, comprising:
a light-emitting diode configured to emit light that is centered around an optical axis;
a lens configured to shape the emitted light to form shaped light, the lens being rotationally symmetric about the optical axis; and
a beam-shaping element coupled to the lens,
the beam-shaping element being rotationally symmetric about the optical axis,
the beam-shaping element being positioned and sized to receive only a central portion of the shaped light,
the beam-shaping element including a pattern of reflective elements that are configured to reflect a first portion of the shaped light toward the lens,
the beam-shaping element allowing a second portion of the shaped light to propagate through the beam-shaping element and away from the lens through one or more spaces between adjacent reflective elements in the pattern.
20. The system of claim 19 , further comprising a plurality of protrusions that fasten the beam-shaping element to the exiting surface of the lens.