Broad spectrum light source calibration systems and related methods
Systems and methods are disclosed for light sources that use the photo-sensitivity of one or more colored LEDs to determine at least a portion of the emission spectrum of a white light source or other broad spectrum light emitter. As described herein, a white LED or other broad spectrum light emitter can be used as the light source, if desired, along with one or more additional colored LEDs, and the same colored LEDs can be used to emit light and to adjust a color point produced by the light source. Applications for the disclosed embodiments include but are not limited to general lighting, LCD backlighting, projectors, and direct emission displays such as OLEDs and digital billboards.
1. A light source having an adjustable color point, comprising:
a broad spectrum light emitter;
an LED with a peak emission wavelength within a spectrum of the broad spectrum light emitter; and
a controller configured to use the LED as a wavelength selective light sensor to measure a portion of the spectrum of the broad spectrum light emitter and to use the LED as a light emitter to produce illumination to adjust a color point of the light source.
2. The light source as recited in claim 1 , wherein the LED is a first LED, and further comprising a second LED, wherein the controller is configured to compare a signal induced on the first LED by light from the broad spectrum light emitter to a signal induced on the first LED by light from the second LED.
3. The light source as recited in claim 2 , wherein the broad spectrum light emitter is a white LED.
4. The light source as recited in claim 3 , wherein the white LED comprises a blue LED.
5. The light source as recited in claim 3 , wherein the white LED comprises a material to convert light from one wavelength to other wavelengths.
6. The light source as recited in claim 5 , wherein the material to convert light from one wavelength to other wavelengths is in physical contact with a blue LED.
7. The light source as recited in claim 3 , wherein a peak emission wavelength of the second LED is within the spectrum of the white LED.
8. The light source as recited in claim 7 , wherein the peak emission wavelength of the second LED is shorter than the peak emission wavelength of the first LED.
9. The light source as recited in claim 8 , wherein the controller is further configured to combine a signal produced by the first LED in response to light from the white LED and a signal produced by the first LED in response to light from the second LED to produce a ratio, and wherein the controller is also configured to compare the ratio to a desired ratio.
10. The light source as recited in claim 9 , wherein the controller is configured to adjust a relative light intensity produced by the broad spectrum light emitter and by the first LED so that the ratio and the desired ratio are substantially equal.
11. The light source as recited in claim 10 , wherein the first LED is green and the second LED is blue.
12. The light source as recited in claim 3 , further comprising a third LED with a peak emission wavelength longer than the first LED peak emission wavelength.
13. The light source as recited in claim 12 , wherein the controller is further configured to combine a signal produced by the third LED in response to light from the white LED and a signal produced by the third LED in response to light from the first LED or second LED to produce a ratio, and wherein the controller circuitry is further configured to compare the second ratio to a desired ratio.
14. The light source as recited in claim 13 , wherein the controller is further configured to adjust a relative light intensity produced by the light source and the first LED or third LED or both the first LED and third LED such that the ratio and the desired ratio are substantially equal.
15. A method for adjusting a color point for a light source, comprising emitting a spectrum of light with a broad spectrum light emitter;
using an LED, having a peak emission wavelength within the spectrum of the broad spectrum light emitter, as a wavelength selective light sensor to measure a portion of the spectrum of the broad spectrum light emitter; and
using the LED as a light emitter to produce illumination to adjust a color point of the light source.
16. The method as recited in claim 15 , further comprising comparing a signal induced on the first LED by light from the broad spectrum light emitter to a signal induced on the first LED by light from a second LED.
17. The method as recited in claim 16 , wherein the broad spectrum light emitter is a white LED.
18. The method as recited in claim 17 , wherein the white LED comprises a blue LED.
19. The method as recited in claim 17 , wherein the white LED comprises a material to convert light from one wavelength to other wavelengths.
20. The method as recited in claim 19 , wherein the material to convert light from one wavelength to other wavelengths is in physical contact with the blue LED.
21. The method as recited in claim 17 , further comprising using a second LED having a peak emission wavelength within the spectrum of the white LED.
22. The method as recited in claim 21 , wherein the peak emission wavelength of the second LED is shorter than the peak emission wavelength of the first LED.
23. The method as recited in claim 22 , further comprising combining a signal produced by the first LED in response to light from the white LED and a signal produced by the first LED in response to light from the second LED to produce a ratio, and comparing the ratio to a desired ratio.
24. The method as recited in claim 23 , further comprising adjusting a relative light intensity produced by the light source and by the first LED so that the ratio and the desired ratio are substantially equal.
25. The method as recited in claim 24 , wherein the first LED is green and the second LED is blue.
26. The method as recited in claim 17 , further comprising providing a third LED with a peak emission wavelength longer than the first LED peak emission wavelength.
27. The method as recited in claim 26 , further comprising combining a signal produced by the third LED in response to light from the white LED and a signal produced by the third LED in response to light from the first LED or second LED to produce a ratio, and comparing the second ratio to a desired ratio.
28. The method as recited in claim 27 , further comprising adjusting a relative light intensity produced by the light source and the first LED or by the lights source and the third LED or the lights source and the first and third LEDs such that the ratio and the desired ratio are substantially equal.
29. A controller for a light source having an adjustable color point, comprising:
control circuitry configured to be coupled to a broad spectrum light emitter and an LED with a peak emission wavelength within a spectrum of the broad spectrum light emitter, the control circuitry being configured to use the LED as a wavelength selective light sensor to measure a portion of the spectrum of the broad spectrum light emitter; and
output driver circuitry configured to be coupled to the broad spectrum light emitter and the LED and to use the LED as a light emitter to adjust a color point for light emitted from the broad spectrum light emitter and the LED.
30. The controller as recited in claim 29 , wherein the LED is a first LED, and wherein the control circuitry is further configured to be coupled to a second LED, and wherein the control circuitry is configured to compare a signal induced on the first LED by light from the broad spectrum light emitter to a signal induced on the first LED by light from the second LED.
31. The controller as recited in claim 30 , wherein the control circuitry is further configured to combine a signal produced by the first LED in response to light from the broad spectrum light emitter and a signal produced by the first LED in response to light from the second LED to produce a ratio, and wherein the control circuitry is also configured to compare the ratio to a desired ratio.
32. The controller as recited in claim 31 , wherein the control circuitry is configured to adjust a relative light intensity produced by broad spectrum light emitter and by the first LED so that the ratio and the desired ratio are substantially equal.