Method and apparatus for providing a passive color control scheme using blue and red emitters

Abstract

A lighting device capable of generating warm or neutral white light using blue light-emitting diodes (“LEDs”), red LEDs, and/or luminescent material that responds to blue LED emission is disclosed. The lighting device includes multiple first solid-state light-emitting structures (“SLSs”), second SLSs, and balancing resistor element. The first SLS such as a string of blue LED dies connected in series is able to convert electrical energy to blue optical light, which is partially turned into longer wavelength emission by the luminescent material. The second SLS such as a red LED die is configured to convert electrical energy to red optical light, wherein the second SLSs are connected in series. While the first SLSs and second SLSs are coupled in parallel, the balancing resistor element provides load balance for current redistribution between the first and second SLSs in response to fluctuation of operating temperature.

What is claimed is: 
     
       1. A light-emitting device, comprising:
 a plurality of first solid-state light-emitting structures (“SLSs”) configured to convert electrical energy to first optical light, wherein the plurality of first SLSs is connected in series, the plurality of first SLSs comprising multiple light emitters able to generate light having a range of wavelength from 400 nm to 500 nm, the plurality of first SLSs comprising light-emitting diodes (“LEDs”) with phosphor configured to convert a portion of blue photons into photons in yellow or green spectral region; 
 a plurality of second SLSs configured to convert electrical energy to second optical light, wherein the plurality of second SLSs is connected in series; 
 a first balancing resistor element coupled to the plurality of first SLSs in series and configured to provide load balance between the plurality of first SLSs and the plurality of second SLSs, wherein the plurality of first SLSs including the first balancing resistor element and the plurality of second SLSs are coupled in parallel allowing current redistribution in response to fluctuation of operating temperature due to the temperature dependent characteristics of the first balancing resistor element; and 
 a second balancing resistor element coupled to the plurality of second SLSs in series, wherein the second balancing resistor element is capable of redistributing current passing through the plurality of second SLSs to compensate differential voltage drop between the plurality of first SLSs and the plurality of second SLSs. 
 
     
     
       2. The device of  claim 1 , wherein the plurality of first SLSs is an array of light-emitting diode (“LED”) chips. 
     
     
       3. The device of  claim 1 , wherein the plurality of first SLSs includes at least one light-emitting diode (“LED”) chip having multiple junctions. 
     
     
       4. The device of  claim 1 , wherein the phosphor is deposited in proximity of the blue LED chips. 
     
     
       5. The device of  claim 1 , wherein the phosphor is located remotely from the blue LED chips. 
     
     
       6. The device of  claim 1 , wherein a plurality of second SLSs configured to convert electrical energy to second optical light includes multiple light emitters capable of generating light in the red or orange wavelength region having a range from 580 nm to 700 nm. 
     
     
       7. The device of  claim 1 , wherein the first balancing resistor element coupled to the plurality of first SLSs and configured to provide load balance between the plurality of first SLSs and the plurality of second SLSs further includes a passive resistor element having a predefined value based on physical properties of blue light-emitting diodes (“LEDs”) and red LEDs wherein combined blue to red light flux generated by blue LEDs and red LEDs together with phosphor conversion generate a predefined desirable color point. 
     
     
       8. A light-emitting device, comprising:
 a plurality of first solid-state light-emitting structures (“SLSs”) configured to convert electrical energy to first optical light, wherein the plurality of first SLSs is connected in series; 
 a plurality of second SLSs configured to convert electrical energy to second optical light, wherein the plurality of second SLSs is connected in series; 
 a first balancing resistor element coupled to the plurality of first SLSs in series and configured to provide load balance between the plurality of first SLSs and the plurality of second SLSs, wherein the plurality of first SLSs including the first balancing resistor element and the plurality of second SLSs are coupled in parallel allowing current redistribution in response to fluctuation of operating temperature due to the temperature dependent characteristics of the first balancing resistor element, wherein the first balancing resistor element includes a passive resistor element having a predefined value based on physical properties of blue light-emitting diodes (“LEDs”) and red LEDs wherein combined blue to red light flux generated by blue LEDs and red LEDs together with phosphor conversion generate a predefined desirable color point; and 
 a second balancing resistor element coupled to the plurality of second SLSs in series and capable of redistributing current passing through the plurality of second SLSs to compensate differential voltage drop between the plurality of first SLSs and the plurality of second SLSs. 
 
     
     
       9. The device of  claim 8 , wherein the plurality of first SLSs is an array of light-emitting diode (“LED”) chips. 
     
     
       10. The device of  claim 8 , wherein the plurality of first SLSs includes at least one light-emitting diode (“LED”) chip having multiple junctions. 
     
     
       11. The device of  claim 8 , wherein the plurality of first SLSs configured to convert electrical energy to first optical light includes multiple light emitters able to generate blue light having a range of wavelength from 400 nm to 500 nm. 
     
     
       12. The device of  claim 11 , wherein the plurality of first SLSs includes blue light-emitting diodes (“LEDs”) having phosphor conversion able to convert a portion of blue photons into photons in yellow or green spectral region. 
     
     
       13. The device of  claim 12 , wherein the phosphor is deposited in proximity of the blue LED chips. 
     
     
       14. The device of  claim 12 , wherein the phosphor is located remotely from the blue LED chips. 
     
     
       15. The device of  claim 11 , wherein a plurality of second SLSs configured to convert electrical energy to second optical light includes multiple light emitters capable of generating light in the red or orange wavelength region having a range from 580 nm to 700 nm. 
     
     
       16. A light-emitting device, comprising:
 a plurality of first solid-state light-emitting structures (“SLSs”) configured to convert electrical energy to first optical light, wherein the plurality of first SLSs is connected in series; 
 a plurality of second SLSs configured to convert electrical energy to second optical light, wherein the plurality of second SLSs is connected in series; and 
 a first balancing resistor element coupled to the plurality of first SLSs in series and configured to provide load balance between the plurality of first SLSs and the plurality of second SLSs, wherein the plurality of first SLSs and the plurality of second SLSs are coupled in parallel allowing current redistribution in response to fluctuation of operating temperature due to the temperature dependent characteristics of the first balancing resistor element, wherein the first balancing resistor element includes a passive resistor element having a predefined value based on physical properties of blue light-emitting diodes (“LEDs”) and red LEDs wherein combined blue to red light flux generated by blue LEDs and red LEDs together with phosphor conversion generate a predefined desirable color point. 
 
     
     
       17. The device of  claim 16 , further comprising a second balancing resistor element coupled to the plurality of second SLSs in series and capable of redistributing current passing through the plurality of second SLSs to compensate differential voltage drop between the plurality of first SLSs and the plurality of second SLSs. 
     
     
       18. The device of  claim 16 , wherein the plurality of first SLSs is an array of light-emitting diode (“LED”) chips. 
     
     
       19. The device of  claim 16 , wherein the plurality of first SLSs includes at least one light-emitting diode (“LED”) chip having multiple junctions. 
     
     
       20. The device of  claim 16 , wherein the plurality of first SLSs configured to convert electrical energy to first optical light includes multiple light emitters able to generate blue light having a range of wavelength from 400 nm to 500 nm. 
     
     
       21. The device of  claim 20 , wherein the plurality of first SLSs includes blue light-emitting diodes (“LEDs”) having phosphor conversion able to convert a portion of blue photons into photons in yellow or green spectral region. 
     
     
       22. The device of  claim 21 , wherein the phosphor is deposited in proximity of the blue LED chips. 
     
     
       23. The device of  claim 22 , wherein the phosphor is located remotely from the blue LED chips. 
     
     
       24. The device of  claim 20 , wherein a plurality of second SLSs configured to convert electrical energy to second optical light includes multiple light emitters capable of generating light in the red or orange wavelength region having a range from 580 nm to 700 nm.