LED Filaments and LED Filament Lamps

Abstract

An LED-filament includes a partially light-transmissive substrate; blue LED chips mounted on a front face of the substrate; first broad-band green to red photoluminescence materials and a first narrow-band manganese-activated fluoride red photoluminescence material covering the blue LED chips and the front face of the substrate; and second broad-band green to red photoluminescence materials covering the back face of the substrate. The LED-filament can further include a second narrow-band manganese-activated fluoride red photoluminescence material on the back face of the substrate in an amount that is less than 5 wt % of a total red photoluminescence material content on the back face of the substrate.

1 - 21 . (canceled) 
     
     
         22 . An LED-filament comprising:
 a partially light-transmissive substrate;   a plurality of blue LED chips on a front face of the substrate;   first green to red photoluminescence materials including manganese-activated fluoride red photoluminescence material and covering the plurality of blue LED chips and the front face of the substrate; and   second green to red photoluminescence materials covering the back face of the substrate;   wherein an amount of manganese-activated fluoride red photoluminescence material on the back face of the substrate is less than an amount of manganese-activated fluoride red photoluminescence material on the front face of the substrate.   
     
     
         23 . The LED-filament of  claim 22 , wherein the first green to red photoluminescence materials comprise a two layer structure comprising a first layer containing the manganese-activated red photoluminescence material disposed on the plurality of blue LED chips, and a second layer disposed on the first layer. 
     
     
         24 . The LED-filament of  claim 23 , wherein the first layer comprises a uniform thickness layer on at least a principle light emitting face of the LED chips. 
     
     
         25 . (canceled) 
     
     
         26 . The LED-filament of  claim 22 , wherein the first green to red photoluminescence materials comprise a single layer. 
     
     
         27 . (canceled) 
     
     
         28 . The LED-filament of  claim 22 , wherein the manganese-activated red photoluminescence material is at least one of: K 2 SiF 6 :Mn 4+ , K 2 GeF 6 :Mn 4+ , and K 2 TiF 6 :Mn 4+ . 
     
     
         29 . The LED-filament of  claim 22 , wherein at least one of the first green to red photoluminescence material and the second green to red photoluminescence materials comprises at least one of: a nitride-based phosphor material having a general composition AAlSiN 3 :Eu 2+  where A is at least one of Ca, Sr or Ba; a sulfur-based phosphor material having a general composition (Ca 1-x Sr x )(Se 1-y S y ):Eu 2+  where 0≤x≤1 and 0<y≤1; a silicate-based phosphor material having a general composition (Ba 1-x Sr x ) 3 SiO 5 :Eu 2+  where 0≤x≤1 and combinations thereof. 
     
     
         30 . The LED-filament of  claim 22 , wherein the substrate has a transmittance of at least one of: from 2% to 70%, from 30% to 50%, and from 10% to 30%. 
     
     
         31 . The LED-filament of  claim 22 , wherein the light-transmissive substrate comprises a material selected from the group consisting of: alumina, silica, magnesium oxide, sapphire, quartz glass, diamond, silicon oxide and mixtures thereof. 
     
     
         32 . An LED-filament comprising:
 a partially light-transmissive substrate;   a plurality of blue LED chips on a front face of the substrate;   a first layer comprising a first manganese-activated fluoride red photoluminescence material, wherein the first layer is continuous and is disposed on and covers the plurality of blue LED chips; and   a second layer comprising a first green to red photoluminescence material disposed on the first layer.   
     
     
         33 . The LED-filament of  claim 32 , wherein the substrate has a transmittance in a range from 20% to 100%. 
     
     
         34 . The LED-filament of  claim 32 , wherein the first layer comprises a uniform thickness layer on at least a principle light emitting face of the LED chips. 
     
     
         35 . The LED-filament of  claim 32 , further comprising a third layer comprising a manganese-activated fluoride red photoluminescence material disposed on the back face of the substrate; and a fourth layer comprising a second green to red photoluminescence material disposed on the third layer. 
     
     
         36 . The LED-filament of  claim 32 , wherein the manganese-activated red photoluminescence material is at least one of: K 2 SiF 6 :Mn 4+ , K 2 GeF 6 :Mn 4+ , and K 2 TiF 6 :Mn 4+ . 
     
     
         37 . The LED-filament of  claim 32 , wherein at least one of the first green to red photoluminescence material and the second green to red photoluminescence materials comprises at least one of: a nitride-based phosphor material having a general composition AAlSiN 3 :Eu 2+  where A is at least one of Ca, Sr or Ba; a sulfur-based phosphor material having a general composition (Ca 1-x Sr x )(Se 1-y S y ):Eu 2+  where 0≤x≤1 and 0<y≤1; a silicate-based phosphor material having a general composition (Ba 1-x Sr x ) 3 SiO 5 :Eu 2+  where 0≤x≤1; and combinations thereof. 
     
     
         38 . The LED-filament of  claim 32 , wherein
 the first green to red photoluminescence materials comprises a non-manganese-activated red photoluminescence material and   wherein a content of the non-manganese-activated red photoluminescence material with respect to the total of the manganese-activated red photoluminescence material and non-manganese-activated red photoluminescence material is at least one of: at least 20 wt % at least 30 wt %, at least 40 wt %, and from about 20 wt % to about 60 wt %.   
     
     
         39 - 42 . (canceled) 
     
     
         43 . The LED-filament of  claim 22 , wherein the second green to red photoluminescence materials include a manganese-activated fluoride red photoluminescence material in an amount with respect to the total amount of red photoluminescence material in the second green to red photoluminescence materials from 0 wt % to 5 wt %. 
     
     
         44 . The LED-filament of  claim 23 , wherein the first layer is continuous and covers the plurality of blue LED chips. 
     
     
         45 . The LED-filament of  claim 22 , wherein the first green to red photoluminescence materials comprise a non-manganese-activated red photoluminescence material and wherein a content of the non-manganese-activated red photoluminescence material with respect to the total of the manganese-activated red photoluminescence material and non-manganese-activated red photoluminescence material is at least one of: at least 20 wt %, at least 30 wt %, at least 40 wt %, and from about 20 wt % to about 60 wt %. 
     
     
         46 . An LED-filament comprising:
 a partially light-transmissive substrate;   a plurality of blue LED chips on a front face of the substrate; and   manganese-activated fluoride red photoluminescence material;   wherein there is a lesser amount of manganese-activated fluoride red photoluminescence material on the back face of the substrate than on the front face of the substrate.   
     
     
         47 . The LED-filament of  claim 46 , wherein the manganese-activated red photoluminescence material is at least one of: K 2 SiF 6 :Mn 4+ , K 2 GeF 6 :Mn 4+ , and K 2 TiF 6 :Mn 4+ . 
     
     
         48 . The LED-filament of  claim 46 , further comprising a red photoluminescence material on the back face of the substrate and wherein the amount of manganese-activated fluoride red photoluminescence material with respect to the total amount of red photoluminescence material is from 0 wt % to 5 wt %.