Dimmable led light fixture maintaining brightness during color temperature change

Abstract

A method of operating an LED lamp coupled with a dimmer switch and includes receiving an input signal from the dimmer switch corresponding to a setting of the dimmer switch within its dimmable range, detecting a change of the setting within the upper portion of the dimmable range, which includes 80% to 100% of a maximum setting of the dimmer switch, and, responsive to detecting the change, adjusting drive current to at least one of a first or a LED light source to change a composite CCT produced by them within a first CCT range including about 3000 Kelvin to about 5000 Kelvin while substantially maintaining a composite brightness produced by the first and second LED light sources.

The invention claimed is: 
     
         1 . An LED lamp for operation with an input signal received from a dimmer switch, the dimmer switch having a dimmable range comprising an upper portion and a lower portion, the input signal corresponding to a setting of the dimmer switch, the LED lamp comprising:
 a first LED light source having a first correlated color temperature (CCT);   a second LED light source having a second CCT different from the first CCT,
 wherein first light emitted from the first LED light source and second light emitted from the second LED light source combine during operation to produce a composite light having a brightness and a composite CCT; and 
   control circuity coupled with the first and second LED light sources and configured to couple with the input signal and drive the first and second LED light sources based thereon, wherein the control circuitry is further configured to:
 substantially maintain the brightness of the composite light while reducing the composite CCT in a first CCT range including about 3000 Kelvin to about 5000 Kelvin responsive to reductions of the setting of the dimmer switch that are within the upper portion of the dimmable range, wherein the upper portion of the dimmable range includes 80% to 100% of a maximum setting of the dimmer switch, and 
 reduce the brightness of the composite light while reducing the composite CCT in a second CCT range including CCTs at or above 2000 Kelvin responsive to reductions of the setting of the dimmer switch that are within the lower portion of the dimmable range. 
   
     
     
         2 . The LED lamp of  claim 1 , wherein the upper portion of the dimmable range comprises the dimmable range above a threshold value, and the lower portion of the dimmable range comprises the dimmable range below the threshold value. 
     
     
         3 . The LED lamp of  claim 2 , wherein the threshold value is about 80% of a maximum setting of the dimmer switch. 
     
     
         4 . The LED lamp of  claim 1 , wherein the first CCT is between 5000 and 6000 Kelvin. 
     
     
         5 . The LED lamp of  claim 4 , wherein the first CCT is about 5000 Kelvin. 
     
     
         6 . The LED lamp of  claim 4 , wherein the first CCT is about 6000 Kelvin. 
     
     
         7 . The LED lamp of  claim 1 , wherein the second CCT is about 2000 Kelvin. 
     
     
         8 . The LED lamp of  claim 1 , wherein the control circuitry is further configured to substantially maintain the brightness of the composite light while increasing the composite CCT responsive to increases of the setting of the dimmer switch that are within the upper portion of the dimmable range. 
     
     
         9 . The LED lamp of  claim 1 , wherein the control circuitry is further configured to increase the brightness of the composite light while increasing the composite CCT responsive to increases of the setting of the dimmer switch that are within the lower portion of the dimmable range. 
     
     
         10 . A method of operating an LED lamp coupled with a dimmer switch and having a first LED light source having a first correlated color temperature (CCT) and a second LED light source having a second CCT different from the first CCT, the dimmer switch having a dimmable range comprising an upper portion and a lower portion, the method comprising:
 receiving an input signal from the dimmer switch, the input signal corresponding to a setting of the dimmer switch within the dimmable range;   detecting a change of the setting within the upper portion of the dimmable range, wherein the upper portion of the dimmable range includes 80% to 100% of a maximum setting of the dimmer switch;   responsive to detecting the change of the setting within the upper portion of the dimmable range, adjusting drive current to at least one of the first or second LED light sources to change a composite CCT produced by the first and second LED light sources within a first CCT range including about 3000 Kelvin to about 5000 Kelvin while substantially maintaining a composite brightness produced by the first and second LED light sources.   
     
     
         11 . The method of  claim 10 , wherein the change of the setting within the upper portion of the dimmable range comprises a reduction of the setting within the upper portion of the dimmable range, and wherein adjusting drive current to at least one of the first or second LED light sources to change the composite CCT produced by the first and second LED light sources while substantially maintaining the composite brightness produced by the first and second LED light sources comprises adjusting drive current to at least one of the first or second LED light sources to reduce the composite CCT produced by the first and second LED light sources while substantially maintaining the composite brightness produced by the first and second LED light sources. 
     
     
         12 . The method of  claim 10 , further comprising:
 detecting a change of the setting within the lower portion of the dimmable range;   responsive to detecting the change of the setting within the second portion of the dimmable range, adjusting drive current to at least one of the first LED or second LED light sources to change the composite CCT produced by the first and second LED light sources within a second CCT range including CCTs at or above 2000 Kelvin while changing the composite brightness produced by the first and second LED light sources.   
     
     
         13 . The method of  claim 12 , wherein the change of the setting within the second portion of the dimmable range comprises a reduction of the setting within the lower portion of the dimmable range, and wherein adjusting drive current to at least one of the first or second LED light sources to change the composite CCT produced by the first and second LED light sources while changing the composite brightness produced by the first and second LED light sources comprises adjusting drive current to at least one of the first or second LED light sources to reduce the composite CCT produced by the first and second LED light sources while reducing the composite brightness produced by the first and second LED light sources. 
     
     
         14 . An LED lamp for operation with an input signal received from a dimmer switch, the dimmer switch having a dimmable range comprising an upper portion and a lower portion, the input signal corresponding to a setting of the dimmer switch, the LED lamp comprising:
 a first LED light source having a first correlated color temperature (CCT);   a second LED light source having a second CCT different from the first CCT, wherein first light emitted from the first LED light source and second light emitted from the second LED light source combine during operation to produce a composite light having a brightness and a composite CCT; and   control circuity coupled with the first and second LED light sources and configured to couple with the input signal and drive the first and second LED light sources based thereon, wherein the control circuitry is further configured to:
 substantially maintain the brightness of the composite light while increasing the composite CCT in a first CCT range including about 3000 Kelvin to about 5000 Kelvin responsive to increases of the setting of the dimmer switch that are within the upper portion of the dimmable range, wherein the upper portion of the dimmable range includes 80% to 100% of a maximum setting of the dimmer switch, and 
 increase the brightness of the composite light while increasing the composite CCT in a second CCT range including CCTs at or above 2000 Kelvin responsive to increases of the setting of the dimmer switch that are within the lower portion of the dimmable range. 
   
     
     
         15 . The LED lamp of  claim 14 , wherein the first CCT is about 5000 Kelvin. 
     
     
         16 . The LED lamp of  claim 14 , wherein the first CCT is about 6000 Kelvin. 
     
     
         17 . The LED lamp of  claim 14 , wherein the second CCT is about 2000 Kelvin. 
     
     
         18 . A method of operating an LED lamp coupled with a dimmer switch and having a first LED light source having a first correlated color temperature (CCT) and a second LED light source having a second CCT different from the first CCT, the dimmer switch having a dimmable range comprising an upper portion and a lower portion, the method comprising:
 receiving an input signal from the dimmer switch, the input signal corresponding to a setting of the dimmer switch within the dimmable range;   detecting a reduction of the setting within the upper portion of the dimmable range, wherein the upper portion of the dimmable range includes 80% to 100% of a maximum setting of the dimmer switch;   responsive to detecting the reduction of the setting within the upper portion of the dimmable range, adjusting drive current to at least one of the first or second LED light sources to reduce a composite CCT produced by the first and second LED light sources within a first CCT range including about 3000 Kelvin to about 5000 Kelvin while substantially maintaining a composite brightness produced by the first and second LED light sources;   detecting an increase of the setting within the upper portion of the dimmable range;   responsive to detecting the increase of the setting within the upper portion of the dimmable range, adjusting drive current to at least one of the first or second LED light sources to increase the composite CCT with in the first CCT range while substantially maintaining the composite brightness produced by the first and second LED light sources;   detecting a reduction of the setting within the lower portion of the dimmable range;   responsive to detecting the reduction of the setting within the lower portion of the dimmable range, adjusting drive current to at least one of the first or second LED light sources to reduce the composite CCT within a second CCT range including CCTs at or above about 2000 Kelvin while reducing composite brightness produced by the first and second LED light sources;   detecting an increase of the setting within the lower portion of the dimmable range; and   responsive to detecting the increase of the setting within the lower portion of the dimmable range, adjusting drive current to at least one of the first or second LED light sources to increase the composite CCT within the second CCT range while substantially increasing the composite brightness produced by the first and second LED light sources.   
     
     
         19 . A method of operating an LED lamp coupled with a dimmer switch and having a first LED light source having a first correlated color temperature (CCT) and a second LED light source having a second CCT different from the first CCT, the dimmer switch having a dimmable range, the method comprising:
 receiving an input signal from the dimmer switch, the input signal corresponding to a setting of the dimmer switch within the dimmable range;   detecting a change of the setting within an upper portion of the dimmable range, wherein the upper portion of the dimmable range comprises the dimmable range above a threshold value;   responsive to detecting the change of the setting within the upper portion of the dimmable range, adjusting drive current to at least one of the first or second LED light sources to change a composite CCT produced by the first and second LED light sources while substantially maintaining a composite brightness produced by the first and second LED light sources.   
     
     
         20 . The method of  claim 19  further comprising:
 detecting a change of the setting within a lower portion of the dimmable range, wherein the lower portion of the dimmable range comprises the dimmable range below a threshold value; 
 responsive to detecting the change of the setting within the lower portion of the dimmable range, adjusting drive current to at least one of the first or second LED light sources to change a composite CCT produced by the first and second LED light sources while changing a composite brightness produced by the first and second LED light sources. 
 
     
     
         21 . The method of  claim 19 , wherein the threshold value is about 80% of a maximum setting of the dimmer switch. 
     
     
         22 . The method of  claim 19 , wherein the composite CCT at the threshold value is about 3000 Kelvin.