Light emitting device

1. A light-emitting device comprising:

a substrate comprising a top surface and a bottom surface opposite to the top surface; and

a plurality of LED chips disposed on the top surface and configured to generate a top light visible above the top surface and a bottom light visible beneath the bottom surface, each LED chip comprising a plurality of light-emitting surfaces;

wherein the substrate has a thickness greater than 200 μm and comprises aluminum oxide, sapphire, glass, plastic, or rubber,

wherein the plurality of LED chips has an incident light with a wavelength of 420-470 nm, and

wherein the top light and the bottom light have a color temperature difference of not greater than 1500K.

2. The light-emitting device of claim 1 , further comprising a first conductor and a second conductor located on the substrate and electrically connected to the plurality of LED chips.

3. The light-emitting device of claim 2 , wherein the each LED chip comprises a first electrode and a second electrode electrically connected to the first conductor and the second conductor respectively.

4. The light-emitting device of claim 1 , further comprising a wavelength conversion layer comprising a first portion covering the top surface and a second portion covering the bottom surface.

5. The light-emitting device of claim 4 , wherein the first portion of the wavelength conversion layer contacts the plurality of LED chips.

6. The light-emitting device of claim 4 , wherein the first portion and the second portion of the wavelength conversion layer comprise one or more kinds of fluorescent powders.

7. The light-emitting device of claim 1 , wherein the substrate is transparent to a light emitted from the plurality of LED chips.

8. The light-emitting device of claim 1 , wherein the substrate has a transmissivity greater than or equal to 70%.

9. A light-emitting apparatus comprising:

the light-emitting device of claim 1 ; and

a support base coupled to the substrate;

wherein the substrate is inclined with respect to the support base by an angle of from 30° to 150°.

10. The light-emitting apparatus of claim 9 , further comprising a wavelength conversion layer comprising a first portion covering the top surface and a second portion covering the bottom surface.

11. The light-emitting apparatus of claim 9 , wherein the first portion and the second portion of the wavelength conversion layer comprise one or more kinds of fluorescent powders.

12. The light-emitting apparatus of claim 9 , further comprising a support, wherein the light-emitting device is coupled to the support base through the support.

13. The light-emitting apparatus of claim 12 , wherein the support base and the support are physically distinguished from each other.

14. The light-emitting apparatus of claim 9 , wherein the support base has a virtual center axis, the plurality of LED chips does not directly face to the virtual center axis.

15. The light-emitting apparatus of claim 14 , further comprising another light-emitting device of claim 1 , which is coupled to the support base.

16. The light-emitting apparatus of claim 15 , wherein the plurality of LED chips of the another light-emitting device does not directly face to the virtual center axis.

17. The light-emitting apparatus of claim 9 , further comprising a lamp housing covering the light-emitting device and the support base.

18. The light-emitting apparatus of claim 17 , wherein the lamp housing and the light-emitting device are separated from each other by a distance of not equal to zero.

19. The light-emitting apparatus of claim 9 , wherein the substrate has a transmissivity greater than or equal to 70%.