Light emitting device with high color rendering index and high luminescence efficiency
A light emitting device comprises two light-emitting diode (LED) groups, a group of luminophor layers, and an input terminal. The first LED group includes at least one blue LED emitting light having a dominant wavelength in a range between 400 nm and 480 nm, and the second LED group includes at least one red-orange LED emitting light having a dominant wavelength in a range between 610 nm and 630 nm. The group of luminophor layers, which are selected from one of silicates, nitrides, and nitrogen oxides, are positioned above the first LED group and partially converts the light emitted by the first LED group into light having a dominant wavelength in a range between 500 nm and 555 nm. The input terminal is connected to the two LED groups for providing desired electric energy thereto.
1. A light emitting device, comprising:
a first light emitting diode (LED) group including at least a blue light LED, the blue light LED emitting light having a dominant wavelength in a range between 400 nm and 480 nm;
a second LED group including at least a red-orange light LED, the red-orange light LED emitting light having a dominant wavelength in a range between 610 nm and 630 nm;
a group of luminophor layers located above the first LED group, being able to be excited by a portion of the light emitted by the first LED group to emit light having a dominant wavelength in a range between 500 nm and 555 nm;
a transparent layer located above the first LED group and the second LED group;
an anti-reflective coating above the transparent layer; and
an input terminal connected to the first LED group and the second LED group, for providing energy to enable the first LED group and the second LED group to emit light;
wherein a mixture of light of the light emitted by the first LED group and fluorescence emitted by exciting the group of luminophor layers falls in an area constructed of six point coordinates and six line segments within the CIE 1931 color space, the six coordinates being sequentially a first point (0.359, 0.481), a second point (0.320, 0.520), a third point (0.220, 0.320), a fourth point (0.260, 0.285), a fifth point (0.359, 0.379), and a sixth point (0.319, 0.399), and the six line segments including a first line segment connecting the first point and the second point, a second line segment connecting the second point and the third point, a third line segment connecting the third point and the fourth point, a fourth line segment connecting the fourth point and the fifth point, a fifth line segment connecting the fifth point and the sixth point, and a sixth line segment connecting the sixth point and the first point.
2. The light emitting device of claim 1 , wherein the first LED group is parallelly connected to the second LED group.
3. The light emitting device of claim 1 , wherein the first LED group is serially connected to the second LED group.
4. The light emitting device of claim 1 , wherein the first LED group and the second LED group include at least an LED unit respectively.
5. The light emitting device of claim 4 , wherein the LED units located respectively in the first LED group and the second LED group are parallelly connected.
6. The light emitting device of claim 4 , wherein the LED units located respectively in the first LED group and the second LED group are serially connected.
7. The light emitting device of claim 4 , wherein the sizes of the LED units located respectively in the first LED group and the second LED group are different.
8. The light emitting device of claim 1 , wherein the first LED group and the second LED group are controlled separately.
9. The light emitting device of claim 1 , wherein the group of luminophor layers are selected from at least one of silicates, nitrides and oxides.
10. The light emitting device of claim 1 , wherein the group of luminophor layers includes at least a fluorescent layer.
11. The light emitting device of claim 1 , further comprising a concave structure with a reflective inner surface, the first LED group and the second LED group being disposed on the reflective inner surface of the concave structure, and the reflective inner surface of the concave structure being able to reflect the light emitted by the first LED group, the second LED group and the group of luminophor layers.
12. The light emitting device of claim 1 , wherein the anti-reflective coating includes at least one transparent material of nitrocellulose, cellulose esters, cellulose acetate, cellulose acetate butyrate, Teflon, Cytop, SiO 2 , SiN x , SiO x N y , TiO 2 , MgO, or MgF 2 .
13. The light emitting device of claim 1 , wherein the anti-reflective coating is formed by at least one of spin-coating, dip-coating, chemical vapor deposition (CVD), thermal evaporation coating, and e-beam evaporation coating.
14. The light emitting device of claim 1 , further comprising:
a diffusion layer located above the first LED group, the second LED group and the group of luminophor layers, enabling the light emitted by the first LED group, the second LED group and the group of luminophor layers to be mixed more uniformly.
15. A light emitting device, comprising:
a base;
a first light emitting diode (LED) group including at least a blue light LED, the blue light LED emitting light having a dominant wavelength in a range between 400 nm and 480 nm;
a second LED group including at least a red-orange light LED, the red-orange light LED emitting light having a dominant wavelength in a range between 610 nm and 630 nm;
a first transparent layer coated on the first LED group and the second LED group;
a group of luminophor layers located above the first transparent layer, being able to be excited by a portion of light emitted by the first LED group to emit light having a dominant wavelength in a range between 500 nm and 555 nm;
an anti-reflective coating disposed between the first transparent layer and the group of luminophor layers; and
an input terminal connected to the first LED group and the second LED group, for providing energy to enable the first LED group and the second LED group to emit light;
wherein a mixture of light of the light emitted by the first LED group and fluorescence emitted by exciting the group of luminophor layers falls in an area constructed of six point coordinates and six line segments within the CIE 1931 color space, the six coordinates being sequentially a first point (0.359, 0.481), a second point (0.320, 0.520), a third point (0.220, 0.320), a fourth point (0.260, 0.285), a fifth point (0.359, 0.379), and a sixth point (0.319, 0.399), and the six line segments including a first line segment connecting the first point and the second point, a second line segment connecting the second point and the third point, a third line segment connecting the third point and the fourth point, a fourth line segment connecting the fourth point and the fifth point, a fifth line segment connecting the fifth point and the sixth point, and a sixth line segment connecting the sixth point and the first point.
16. The light emitting device of claim 15 , wherein the base has a reflective surface, the first LED group and the second LED group are disposed on the reflective surface of the base, and the reflective surface reflects light emitted by the first LED group, the second LED group and the group of luminophor layers.
17. The light emitting device of claim 15 , wherein the first LED group is parallelly connected to the second LED group.
18. The light emitting device of claim 15 , wherein the first LED group is serially connected to the second LED group.
19. The light emitting device of claim 15 , wherein the first LED group and the second LED group include at least an LED unit respectively.
20. The light emitting device of claim 19 , wherein the LED units located respectively in the first LED group and the second LED group are parallelly connected.
21. The light emitting device of claim 19 , wherein the LED units located respectively in the first LED group and the second LED group are serially connected.
22. The light emitting device of claim 19 , wherein the LED units located respectively in the first LED group and the second LED group are controlled separately.
23. The light emitting device of claim 15 , wherein the first LED group and the second LED group are controlled separately.
24. The light emitting device of claim 23 , wherein the surface of the group of luminophor layers is hemispherical, convex, or planar.
25. The light emitting device of claim 15 , wherein the group of luminophor layers are selected from one of silicates, nitrides and nitrogen oxides.
26. The light emitting device of claim 15 , wherein the group of luminophor layers includes at least a fluorescent layer.
27. The light emitting device of claim 15 , wherein the first transparent layer includes at least one transparent material of epoxy, silicone, polyimide, glass, quartz, acryl, polycarbonate (PC), or parylene.
28. The light emitting device of claim 15 , wherein the first transparent layer is hemispherical, convex, tapered or Fresnel-lens-shaped.
29. The light emitting device of claim 15 , wherein the anti-reflective coating includes at least one transparent material of nitrocellulose, cellulose esters, cellulose acetate, cellulose acetate butyrate, Teflon, Cytop, SiO 2 , SiN x , SiO x N y , TiO 2 , MgO, or MgF 2 .
30. The light emitting device of claim 15 , wherein the anti-reflective coating is formed by at least one of spin-coating, dip-coating, chemical vapor deposition (CVD), thermal evaporation coating, and e-beam evaporation coating.
31. The light emitting device of claim 15 , further comprising:
a hollow layer disposed between the first transparent layer and the group of luminophor layers, the thickness of the hollow layer being between 0.01 mm and 10 mm.
32. The light emitting device of claim 31 , wherein the hollow layer includes air.
33. The light emitting device of claim 15 , further comprising:
a diffusion layer located above the group of luminophor layers, enabling light emitted by the first LED group, the second LED group and the group of luminophor layers to be mixed more uniformly.
34. The light emitting device of claim 33 , further comprising:
a second transparent layer disposed between the diffusion layer and the group of luminophor layers, being configured to further protect the group of luminophor layers and a structure thereunder from an influence of moisture.
35. The light emitting device of claim 34 , wherein the second transparent layer is hemispherical, convex, tapered or Fresnel-lens-shaped.
36. The light emitting device of claim 15 , further comprising a transparent packaging layer located above the group of luminophor layers.
37. The light emitting device of claim 36 , wherein the transparent packaging layer includes at least one transparent material of epoxy, silicone, polyimide, glass, quartz, acryl, polycarbonate (PC), or parylene.
38. The light emitting device of claim 36 , wherein the transparent packaging layer is hemispherical, convex, tapered or Fresnel-lens-shaped.
39. The light emitting device of claim 15 , wherein the base is formed of a semiconductor, a metal, a ceramics or a metal matrix composite.