Led lamp with current-regulated warm dimming

Abstract

In one embodiment, an LED filament lamp for warm dimming is presented that includes a dimmable LED driver circuit; a first channel LED filament having a first forward voltage drop which emits a first white light of a first correlated color temperature; and a second channel LED filament having a second forward voltage drop and which emits a second white light of a second correlated color temperature warmer than the first correlated color temperature. In another embodiment, an LED filament for warm dimming lamps is presented that includes a light-transmissive substrate; at least one LED die and one non-light-emitting current regulator mounted thereon and connected in series; and an adhesive bead with fluorescent particles suspended therein affixed to the light-transmissive substrate, wherein illuminating the fluorescent particles with the at least one LED die causes the LED filament to emit white light of a predetermined correlated color temperature.

What is claimed is: 
     
         1 . An LED filament lamp for warm dimming, comprising:
 a dimmable LED driver circuit;   a first channel LED filament having a first forward voltage drop which emits a first white light of a first correlated color temperature; and   a second channel LED filament having a second forward voltage drop and which emits a second white light of a second correlated color temperature warmer than the first correlated color temperature.   
     
     
         2 . The LED lamp of  claim 1 , wherein the LED filaments comprise:
 a light-transmissive substrate formed of a transparent or translucent material;   more than one LED die mounted on the light-transmissive substrate;   adhesive beads adhering to opposite sides of the light-transmissive substrate; and   fluorescent particles suspended within the adhesive bead, which when illuminated by the LED dies, cause the filament to emit white light.   
     
     
         3 . The LED lamp of  claim 1 , wherein the second channel LED filament comprises a non-light-emitting current regulator mounted on a light transmissive substrate. 
     
     
         4 . The LED lamp of  claim 1 , wherein the second forward voltage drop is lower than the first forward voltage drop, to cause preferential illumination of the second channel LED filament over the first channel LED filament when the current supplied by the dimmable LED driver circuit is low. 
     
     
         5 . The LED lamp of  claim 1 , wherein the second forward voltage drop is lower than the first forward voltage drop, to cause illumination of the first channel LED filament in addition to illumination of the second channel LED filament when the current supplied by the dimmable LED driver circuit is high. 
     
     
         6 . The LED lamp of  claim 1 , wherein the second forward voltage drop is lower than the first forward voltage drop, to cause an aggregate of the first and second white lights to warm towards the second correlated color temperature as current supplied by the dimmable LED driver circuit is reduced from high to low and the first channel filament dims to an unilluminated state before the second channel filament begins dimming. 
     
     
         7 . The LED lamp of  claim 1 , wherein the dimmable LED driver circuit is a single channel LED driver circuit powering both the first channel LED filament and the second channel LED filament. 
     
     
         8 . The LED lamp of  claim 1 , further comprising:
 an envelope;   a support mount that extends into a cavity within the envelope along an axis of the envelope;   upper and lower conductive supports extending outward into the cavity, wherein the first and second channel LED filaments are conductively and mechanically attached between the conductive supports; and   a base cap affixed to a base of the LED lamp, wherein the dimmable LED driver circuit is concealed within the base cap.   
     
     
         9 . The LED lamp of  claim 8 , wherein the envelope and support mount are each made of glass, and the envelope and support mount are sealed together in an airtight seal. 
     
     
         10 . The LED lamp of  claim 1 , wherein the envelope is frosted or given a soft white coating. 
     
     
         11 . The LED lamp of  claim 1 , wherein the LED lamp has a reflector form factor or parabolic aluminized reflector form factor. 
     
     
         12 . The LED lamp of  claim 1 , wherein the LED lamp has a decorative form factor. 
     
     
         13 . The LED lamp of  claim 1 , further comprising a translucent plastic envelope. 
     
     
         14 . The LED lamp of  claim 1 , wherein the first channel LED filament is connected in parallel with the second channel LED filament. 
     
     
         15 . The LED lamp of  claim 1 , further comprising an additional first channel LED filament or an additional second channel LED filament. 
     
     
         16 . The LED lamp of  claim 1 , further comprising
 a third channel LED filament having a third forward voltage drop and which emits a third white light of a third correlated color temperature warmer than the second correlated color temperature,   wherein the third channel LED filament is connected in parallel with the first channel LED filament and the second channel LED filament; and   wherein the third forward voltage drop is lower than the second forward voltage drop, to cause an aggregate correlated color temperature of the first, second, and third white lights to warm towards an aggregate correlated color temperature of the second and third white lights as current supplied by the dimmable LED driver circuit is reduced from high to low and the first channel filament dims to an unilluminated state before the second channel filament begins dimming.   
     
     
         17 . An LED filament for warm dimming lamps, comprising:
 a light-transmissive substrate;   at least one LED die mounted on the light-transmissive substrate;   at least one non-light-emitting current regulator mounted on the light-transmissive substrate, wherein the current regulator is connected in series with the at least one LED; and   an adhesive bead with fluorescent particles suspended therein affixed to the light-transmissive substrate, wherein illuminating the fluorescent particles with the at least one LED die causes the LED filament to emit white light of a predetermined correlated color temperature.   
     
     
         18 . The LED filament of  claim 17 , wherein the LED filament is incorporated in an LED filament lamp in parallel with another LED filament that has no non-light-emitting current regulator and emits white light of a different predetermined correlated color temperature. 
     
     
         19 . The LED filament of  claim 17 , wherein the adhesive beads include silicone resin. 
     
     
         20 . The LED filament of  claim 17  further comprising a second adhesive bead with the fluorescent particles suspended therein affixed to a second face of the light-transmissive substrate.