Layered phosphor in glass
A phosphor in glass (PiG) cover is provided to modulate the color emitted from an LED chip. The PiG cover includes an active layer including glass and phosphor, and a secondary layer including glass and free of phosphor. The active layer is stacked on the secondary layer to form the PiG cover. Alternately the PiG includes an active layer sandwiched between two secondary layers. Two or more active layers can be stacked to each other or disposed side-by-side. An LED chip is arranged under the PiG cover to form an LED package.
1. A phosphor in glass (PiG) cover including an active layer comprising a glass and phosphor, and a secondary layer contacting the active layer and including the glass and being free of phosphor, wherein the glass comprises 20-60 mol % SiO 2 , 14-50 mol % ZnO, 3-28 mol % B 2 O 3 and 1-21 mol % K 2 O.
2. The PiG cover according to claim 1 , further comprising a second active layer in direct contact with the active layer, wherein the second active layer comprises the glass and phosphor.
3. The PiG cover according to claim 2 , wherein the active layer and the second active layer are stacked together.
4. The PiG cover according to claim 2 , wherein the active layer and the second active layer are disposed side-by-side.
5. The PiG cover according to claim 2 , wherein the phosphor in the second active layer is different from the phosphor in the first active layer.
6. The PiG cover according to claim 1 , further comprising a second secondary layer free of phosphor, wherein the active layer is sandwiched between the secondary layer and the second secondary layer.
7. The PiG cover according to claim 2 , further comprising a second secondary layer free of phosphor, wherein the active layer is sandwiched between the secondary layer and the second secondary layer.
8. The PiG cover according to claim 1 , wherein the glass has a refractive index of about 1.55-1.60.
9. An LED package including the PiG cover according to claim 1 , and an LED chip that emits light through the PiG cover.
10. The LED package according to claim 9 , wherein the LED chip is positioned underneath the PiG.
11. The LED package according to claim 9 , wherein the secondary layer of the PiG is arranged on the same side of the active layer as the LED chip.
12. The LED package according to claim 9 , wherein the glass in the PiG cover has a refractive index of about 1.55-1.60.
13. The PiG cover according to claim 1 , wherein the glass further comprises:
about 1-25 mole % Na 2 O;
up to 20 mole % (Li 2 O+Cs 2 O+Rb 2 O);
up to 25 mole % (BaO+MgO+CaO+SrO);
up to 5 mole % (Sb 2 O 3 +CeO 2 +SnO 2 );
up to 40 mole % (Y 2 O 3 +Al 2 O 3 );
up to 25 mole % (La 2 O 3 +Lu 2 O 3 +Pr 2 O 3 +Gd 2 O 3 +Tb 2 O 3 +Eu 2 O 3 );
up to 25 mole % (TiO 2 +ZrO 2 ); and
up to 25 mole % of anion modifiers.
14. The PiG cover according to claim 13 , wherein the anion modifier comprises F+S+Se.
15. The PiG cover according to claim 1 , wherein the size of the phosphor ranges 5-30 micron.
16. The PiG cover according to claim 1 , wherein a refractive index of the phosphor is same as or differ by ±0.01-0.3 from the refractive index of the glass of the active layer.
17. The PiG cover according to claim 1 , wherein the active layer has thickness of about 120 μm, and the secondary layer has thickness of about 25-100 μm.
18. The PiG cover according to claim 1 , further comprising inorganic filler selected from alumina, anorthite, bismuth oxide, boron oxide, fused silica, crystalline silica (i.e., quartz), magnesium cobalt spinel, molybdenum oxide, titania, titanates, magnesium silicate, calcium silicate, strontium silicate, barium silicate, magnesium titanate, calcium titanate, strontium titanate, barium titanate, eucryptite (both the α- and β-forms are suitable), cordierite, cobalt oxide, chromium oxide, tungsten oxide, zinc oxide, cristobalite (both the α- and β-forms are suitable), zircon, or zirconia.