LED light engine kernel and method of making the kernel
View Patent ↗A light engine kernel for a light emitting diode (LED) includes a solid body of transparent material having an index of refraction of at least 1.5. The body has a domed, light-emitting top that is an inverted parabola of revolution, a reflective sidewall that is a compound parabolic concentrator (CPC), and a cavity at a focus of the CPC that is adapted to receive an LED. The domed top may include a phosphor coating of a yellow-emitting phosphor. The cavity may be adapted to receive only a single LED or plural LEDs of the same or different colors on a board. The kernel and LED are not integrally formed, reducing thermal degradation of the phosphor coating and improving application flexibility.
1. A light engine kernel for a light emitting diode (LED), the kernel comprising: a solid body of transparent material having an index of refraction of at least 1.5, said body having a domed, light-emitting top that is an inverted parabola of revolution, an internally reflective sidewall that is a compound parabolic concentrator (CPC), and a bottom having a cavity therein at a focus of the CPC that is adapted to receive an LED, the CPC being defined by
y
=
(
x
-
δ
)
2
4
h
where δ is a half width and h is a height of said cavity.
2. The kernel of claim 1 , in combination with an LED in said cavity, wherein said cavity is larger than said LED.
3. The kernel of claim 1 , wherein said cavity is adapted to removably receive the LED.
4. The kernel of claim 1 , wherein a focal point of the inverted parabola of revolution is located at a top of said cavity.
5. The kernel of claim 1 , further comprising a reflective coating on an exterior surface of said sidewall.
6. The kernel of claim 1 , further comprising a phosphor coating on an exterior surface of said domed top.
7. The kernel of claim 6 , wherein said phosphor coating comprises at least one of a yellow-emitting, green-emitting, and red-emitting phosphor.
8. The kernel of claim 6 , in combination with a blue-emitting LED in said cavity, wherein said phosphor coating comprises a yellow-emitting phosphor.
9. The kernel of claim 1 , in combination with an LED in said cavity, wherein the index of refraction of said transparent material is substantially the same as an index of refraction of said LED.
10. The kernel of claim 1 , in combination with only a single LED in said cavity.
11. The kernel of claim 1 , in combination with a plurality of LEDs on an LED board in said cavity.
12. The kernel of claim 1 , wherein said transparent material is one of a polymer and glass.
13. The kernel of claim 1 , in combination with a plurality of LEDs on an LED board in said cavity, wherein the CPC comprises a plurality of parabolic surfaces each extending from a side of the LED board and intersecting with each other at a corner of the board.
14. A light engine kernel, comprising:
a solid body of transparent material having an index of refraction of at least 1.5, said solid body having a domed, light-emitting top that is an inverted parabola of revolution, an internally reflective sidewall that is a compound parabolic concentrator (CPC), and a bottom having a cavity therein at a focus of the CPC;
a phosphor coating on an exterior surface of said domed top; and
a light emitting diode (LED) mounted in said cavity, said cavity being adapted to receive said LED,
wherein a focal point of the inverted parabola of revolution is located at a top of said LED, and
wherein the CPC is defined by
y
=
(
x
-
δ
)
2
4
h
where δ is a half width and h is a height of said LED.
15. The kernel of claim 14 , wherein said LED is a blue-emitting LED and said phosphor coating comprises a yellow-emitting phosphor.
16. The kernel of claim 15 , wherein the index of refraction of said transparent material is substantially the same as an index of refraction of said blue-emitting LED.
17. The kernel of claim 14 , in combination with a plurality of LEDs on an LED board in said cavity, wherein the CPC comprises a plurality of parabolic surfaces each extending from a side of the LED board and intersecting with each other at a corner of the board.
18. A method of making a light engine kernel containing a light emitting diode (LED), the method comprising the steps of:
forming a kernel with a solid body of transparent material having an index of refraction of at least 1.5, the body having a domed, light-emitting top that is an inverted parabola of revolution, an internally reflective sidewall that is a compound parabolic concentrator (CPC), and a bottom having a cavity therein at a focus of the CPC, the CPC being defined by
y
=
(
x
-
δ
)
2
4
h
where δ is a half width and h is a height of said cavity; and
thereafter inserting the LED into the formed kernel.
19. The method of claim 18 , further comprising the step of adding a phosphor coating on an exterior surface of the domed top before inserting the LED into the cavity.