Lighting device

1. A lighting device comprising:

a heat sink comprising a top surface, a bottom surface disposed below the top surface and coupling structures which comprise a first coupling structure and a second coupling structure formed on a side surface disposed between the top surface and the bottom surface, the side surface connecting the top surface and the bottom surface;

a light source disposed on the top surface of the heat sink;

a lens unit disposed on the light source and comprising a first coupling portion which is coupled to the first coupling structure formed on the side surface of the heat sink; and

a cover unit comprising an optical member which is disposed on the lens unit, and a second coupling portion which is coupled to the second coupling structure formed on the side surface of heat sink.

2. The lighting device of claim 1 , wherein the side surface is coupled to both sides of the top surface respectively.

3. The lighting device of claim 2 , wherein the first and second coupling structures are a recess, and

wherein a distance from the top surface to the second coupling structure is greater than a distance from the top surface to the first coupling structure.

4. The lighting device of claim 1 , wherein the first coupling portion of the lens unit comprises:

an extension part which is coupled to both sides of the lens unit and is disposed on the top surface of the heat sink; and

a hook which is coupled to the extension part and is inserted into the first coupling structure of the heat sink.

5. The lighting device of claim 1 , wherein the light source comprises a circuit pattern layer disposed on the top surface of the heat sink, and a light emitting device disposed on the circuit pattern layer.

6. The lighting device of claim 5 , wherein the light emitting device comprises a high-voltage (HV) LED chip, and

wherein the HV LED chip has a plurality of light emitting areas.

7. The lighting device of claim 5 , wherein the lens unit comprises a diffuser which is disposed on the light emitting device and diffuses light emitted from the light emitting device, and

wherein a bottom surface of the diffuser has a recess into which the light emitting device is inserted.

8. The lighting device of claim 7 , wherein the lens unit further comprises a guide which is disposed on a bottom surface of the diffuser and guides the light emitting device.

9. The lighting device of claim 1 , wherein the light source comprises a light emitting device,

wherein a plurality of the light emitting devices and a plurality of the lens units are provided, and

wherein the plurality of the lens units are one-to-one or one-to-many correspond to the plurality of the light emitting devices.

10. The lighting device of claim 1 , further comprising:

a power supplier received in a space formed in the heat sink; and

a cap which is coupled to both sides of the heat sink and to both sides of the cover unit and comprises a fixing portion for fixing the power supplier within the space of the heat sink.

11. The lighting device of claim 10 , wherein the fixing portion of the cap protrudes into the space of the heat sink,

wherein the power supplier comprises predetermined parts and a support plate on which the parts are mounted, and

wherein the support plate is coupled to the fixing portion through a screw.

12. A lighting device comprising:

a heat sink having a consistent cross section in a longitudinal direction and comprising a top surface, a bottom surface disposed below the top surface and both side surfaces disposed between the top surface and the bottom surface, each of the side surfaces connecting the top surface and the bottom surface and having a first coupling recess and a second coupling recess which are formed toward the longitudinal direction;

a light source disposed on the top surface of the heat sink;

a lens unit covering the light source and comprising a first coupling portion which is coupled to the first coupling recess of the heat sink; and

a cover unit comprising an optical member covering the lens unit, and a second coupling portion which is coupled to the second coupling recess of the heat sink.

13. The lighting device of claim 12 , wherein the heat sink has a tubular shape with an empty interior.

14. The lighting device of claim 12 , wherein at least a portion of the top surface is upward or downward convex or concave.

15. The lighting device of claim 12 , wherein the heat sink comprises the bottom surface, and

wherein the bottom surface is coupled to the cover unit, so that the lighting device has a cylindrical shape.

16. The lighting device of claim 15 , wherein the top surface, the both side surfaces and the bottom surface define a receiver, and

wherein the lighting device comprises a power supplier disposed in the receiver.

17. The lighting device of claim 12 , wherein the first coupling portion of the lens unit comprises:

an extension part which is coupled to both sides of the lens unit and is disposed on the top surface of the heat sink; and

a hook which is coupled to the extension part and is inserted into the first coupling recess of the heat sink.

18. The lighting device of claim 12 , wherein the light source comprises a circuit pattern layer disposed on the top surface of the heat sink, and a light emitting device disposed on the circuit pattern layer.

19. The lighting device of claim 18 , wherein the light emitting device comprises a high-voltage (HV) LED chip, and

wherein the HV LED chip has a plurality of light emitting areas.

20. The lighting device of claim 18 , wherein the lens unit comprises a diffuser which is disposed on the light emitting device and diffuses light emitted from the light emitting device, and

wherein a bottom surface of the diffuser has a recess into which the light emitting device is inserted.