Emitter module for an LED illumination device
An illumination device comprises one or more emitter modules having improved thermal and electrical characteristics. According to one embodiment, each emitter module comprises a plurality of light emitting diodes (LEDs) configured for producing illumination for the illumination device, one or more photodetectors configured for detecting the illumination produced by the plurality of LEDs, a substrate upon which the plurality of LEDs and the one or more photodetectors are mounted, wherein the substrate is configured to provide a relatively high thermal impedance in the lateral direction, and a relatively low thermal impedance in the vertical direction, and a primary optics structure coupled to the substrate for encapsulating the plurality of LEDs and the one or more photodetectors within the primary optics structure.
1. An illumination device comprising:
a light emitter configured to emit visible light;
a photodetector in close proximity to the emitter configured to detect at least a portion of the visible light emitted by the light emitter; and
a substrate comprising a top surface and a bottom surface, the light source emitter and the photodetector mounted to the top surface of the substrate; and
a heat sink coupled to the bottom surface of the substrate; and
wherein the substrate comprises:
a bottom dielectric layer coupled to the heat sink and configured for providing a first thermal impedance in a lateral direction, and a second thermal impedance lower than the first thermal impedance in a vertical direction.
2. The illumination device of claim 1 wherein the substrate further comprises:
a first thermally conductive line extending from the light emitter through the dielectric layer to the heat sink; and
a second thermally conductive line extending from the photodetector through the dielectric layer to the heat sink.
3. The illumination device of claim 2 wherein:
the dielectric layer comprises material having relatively low thermal conductivity.
4. The illumination device of claim 3 wherein:
the dielectric layer comprises a material having a thermal conductivity less than about 150 W/(mK).
5. The illumination device of claim 2 wherein:
the light emitter comprises at least one light-emitting diode (LED).
6. The illumination device of claim 5 wherein:
the at least one LED comprises an LED selected from the group consisting of a red LED, a green LED, a blue LED, a yellow LED, or a white LED.
7. The illumination device of claim 2 wherein:
the photodetector comprises at least one light-emitting diode (LED).
8. The illumination device of claim 7 wherein:
the photodetector comprises an LED selected from the group consisting of a red LED, a yellow LED, or an orange LED.
9. The illumination device of claim 2 wherein:
the first thermally conductive line comprises material having a thermal conductivity that ranges between about 200 W/(mK) and about 400 W/(mK).
10. The illumination device of claim 2 wherein:
the second thermally conductive line comprises material having a thermal conductivity that ranges between about 200 W/(mK) and about 400 W/(mK).
11. The illumination device of claim 1 wherein:
the substrate comprises a plurality of substrate layers, each substrate layer comprising an upper routing layer and a lower dielectric layer, the uppermost substrate layer comprising an uppermost routing layer configured to be coupled to an electrical contact of the light emitter and to an electrical contact of the photodetector for connecting the light emitter electrical contact and the photodetector electrical contact to external electrical contacts, the lowermost substrate layer comprising a lowermost dielectric layer coupled to the heat sink, each of the plurality of dielectric layers configured to provide electrical isolation between the light emitter and the heat sink, and to provide electrical isolation between the photodetector and the light emitter; and
wherein the bottom dielectric layer comprises the lowermost dielectric layer.
12. The illumination device of claim 11 wherein:
the plurality of substrate layers comprise an upper substrate layer and a lower substrate layer, the upper substrate layer comprising the uppermost routing layer and an upper dielectric layer, the lower substrate layer comprising a lower routing layer and the lowermost dielectric layer;
the substrate further comprising:
a plurality of thermally conductive lines extending from the lower routing layer through the lowermost dielectric layer to the heat sink.
13. The illumination device of claim 12 wherein:
the upper dielectric layer and the lowermost dielectric layer each comprises material having relatively low thermal conductivity.
14. The illumination device of claim 12 wherein:
the plurality of thermally conductive lines comprise material having a thermal conductivity that ranges between about 200 W/(mK) and about 400 W/(mK).
15. The illumination device of claim 11 wherein:
the light emitter comprises at least one light-emitting diode (LED).
16. The illumination device of claim 15 wherein:
the at least one LED comprises an LED selected from the group consisting of a red LED, a green LED, a blue LED, a yellow LED, or a white LED.
17. The illumination device of claim 11 wherein:
the photodetector comprises at least one light-emitting diode (LED).
18. The illumination device of claim 17 wherein:
the photodetector comprises an LED selected from the group consisting of a red LED, a yellow LED, or an orange LED.
19. The illumination device of claim 11 wherein:
the uppermost dielectric layer is configured to provide high thermal impedance in a lateral direction by using a material with a relatively low thermal conductivity.
20. The illumination device of claim 19 wherein:
the uppermost dielectric layer comprises material having a thermal conductivity that is less than about 150 W/(mK).