Method for maintaining light characteristics from a multi-chip LED package
The present invention provides a method, system and structure for maintaining light characteristics from a multi-chip LED package. This may be done by selecting a desired light output and restricting light from a plurality of light emitting diodes in the multi-chip LED package. It may also be done by measuring the restricted light, comparing the measured output light to the desired light and by adjusting current to LEDs in the multi-chip LED package based on the measured light.
1. A method of maintaining light characteristics from a multi-chip light emitting diode (LED) package having a plurality of LED chips, comprising:
providing at least one enclosure having a plurality of apertures, each aperture having a respective predetermined size and facing a respective one of said LED chips;
providing a light sensor disposed in said at least one enclosure, said at least one enclosure being arranged such that each of said plurality of apertures channels light from the corresponding respective one of said LED chips to said light sensor;
restricting light received by said light sensor from said corresponding respective one of said LED chips to produce a restricted light signal, said restricting being proportioned at least in part according to the respective predetermined size of the aperture facing said corresponding respective one of said LED chips;
measuring the restricted light signal produced by said light sensor to produce a sensed light signal;
comparing the sensed light signal to a desired light signal to produce a result; and
adjusting current to at least one LED on the multichip LED package based on the result.
2. The method claimed in claim 1 , characterized in that said at least one enclosure is provided with an interior arranged for efficient combining of light from different light sources through different apertures.
3. The method claimed in claim 2 , characterized in that said interior is provided as a white interior.
4. The method claimed in claim 1 , characterized in that the respective predetermined sizes of at least two apertures of said at least one enclosure are mutually different.
5. The method claimed in claim 4 , characterized in that said at least one enclosure is provided with an interior arranged for efficient combining of light from different light sources through different apertures.
6. The method claimed in claim 5 , characterized in that said interior is provided as a white interior.
7. The method claimed in claim 1 , characterized in that at least two said enclosures are provided, each enclosure having a respective sensor disposed therein;
the respective predetermined sizes of at least two apertures of at least one of said enclosures are mutually different;
one of said LED chips is faced by one respective aperture each of said at least two said enclosures; and
a ratio of the mutually different predetermined sizes is determined at least in part by the inverse of the number of times light from said one of said LED chips is measured.
8. The method claimed in claim 7 , characterized in that measuring the restricted light signal comprises a time multiplex sampling.
9. The method claimed in claim 7 , characterized in that said ratio further depends on the distribution of light actually emitted by said LED chips.
10. The method claimed in claim 9 , characterized in that said at least one enclosure is provided with an interior arranged for efficient combining of light from different light sources through different apertures.
11. A system for providing LED-based light having desired characteristics, comprising:
a multi-chip light emitting diode (LED) package having a plurality of LED chips, said package including at least one light sensor; and
means responsive to a sensed light signal from the light sensor for comparing the sensed light signal to a desired light signal to produce a result, and for controlling current to said LED chips based on the result;
characterized in that the LED package further includes:
means for restricting light received by said light sensor to produce a restricted light signal, said means comprising at least one enclosure having a plurality of apertures, each aperture having a respective predetermined size and facing a respective one of said LED chips, and said at least one light sensor being disposed in said at least one enclosure, said at least one enclosure being arranged such that each of said plurality of apertures channels light from the corresponding respective one of said LED chips to said light sensor, and further arranged such that light received by said at least one light sensor is proportioned at least in part according to the respective predetermined size of the aperture facing said corresponding respective one of said LED chips; and
the system further comprises means for measuring the restricted light signal produced by said light sensor to produce the sensed light signal.
12. The system claimed in claim 11 , characterized in that said at least one enclosure is provided with an interior arranged for efficient combining of light from different light sources through different apertures.
13. The system claimed in claim 12 , characterized in that said interior is provided as a white interior.
14. The system claimed in claim 11 , characterized in that the respective predetermined sizes of at least two apertures of said at least one enclosure are mutually different.
15. The system claimed in claim 14 , characterized in that said at least one enclosure is provided with an interior arranged for efficient combining of light from different light sources through different apertures.
16. The system claimed in claim 11 , characterized in that at least two said enclosures are provided, each enclosure having a respective sensor disposed therein;
the respective predetermined sizes of at least two apertures of at least one of said enclosures are mutually different;
one of said LED chips is faced by one respective aperture each of said at least two said enclosures; and
a ratio of the mutually different predetermined sizes is determined at least in part by the inverse of the number of times light from said one of said LED chips is measured.
17. The system claimed in claim 16 , characterized in that measuring the restricted light signal comprises a time multiplex sampling.
18. The system claimed in claim 16 , characterized in that said ratio further depends on the distribution of light actually emitted by said LED chips.
19. The system claimed in claim 18 , characterized in that said at least one enclosure is provided with an interior arranged for efficient combining of light from different light sources through different apertures.
20. The system claimed in claim 19 , characterized in that said interior is provided as a white interior.