Method and apparatus for testing light-emitting device

1. A method for testing a light-emitting device comprising the steps of:

providing a light-emitting device comprising a plurality of light-emitting diodes;

driving the plurality of the light-emitting diodes with current;

generating an image of the light-emitting device;

determining a luminous intensity of each of the light-emitting diodes with the image; and

comparing the luminous intensity of each of the light-emitting diodes with a pre-determined luminous intensity for determining whether each of the light-emitting diodes is a defective light-emitting diode or not.

2. The method as claimed in claim 1 , wherein the magnitude of the current is a substantially constant value with the current density of each of the light-emitting diodes smaller than or equal to about 300 mA/mm2.

3. The method as claimed in claim 1 , wherein the magnitude of the current is a variant value and is increased with time.

4. The method as claimed in claim 1 , wherein the luminous intensity is determined according to a gray level of the image.

5. The method as claimed in claim 1 , wherein the step of generating the image of the light-emitting device comprises providing an image receiving device and receiving the image of the light-emitting device from the image receiving device.

6. The method as claimed in claim 5 , wherein the image receiving device is a microscope.

7. The method as claimed in claim 5 , wherein the image receiving device further comprises an image sensor to capture the image of the light-emitting device.

8. The method as claimed in claim 5 , wherein the image receiving device further comprises a filter for filtering off a specific range of the wave length of light.

9. The method as claimed in claim 1 , wherein the step of determining the luminous intensity of each of the light-emitting diodes with the image is performed manually by a human being with eyes.

10. The method as claimed in claim 1 , wherein the step of determining the luminous intensity of each of the light-emitting diodes with the image is performed automatically by an automated equipment.

11. The method as claimed in claim 1 , further comprising generating an intensity map showing the position of each of the light-emitting diodes and its corresponding luminous intensity.

12. The method as claimed in claim 1 , further comprising comparing the number of defective light-emitting diodes with a pre-determined number for determining whether the light-emitting device is qualified or not.

13. The method as claimed in claim 12 , further comprising testing the light-emitting device of a wafer form; and generating an qualification status map showing the position of tested area in the wafer and its qualification status, wherein the qualification status comprises a qualified status or an unqualified status.

14. The method as claimed in claim 12 , further comprising marking the unqualified light-emitting device and/or when the luminous intensity is determined automatically by an automated equipment, reconfirming the unqualified light-emitting device manually by a human being with eyes.

15. The method as claimed in claim 1 , wherein the plurality of light-emitting diodes is monolithically formed as a chip.

16. The method as claimed in claim 1 , wherein the plurality of light-emitting diodes is connected in series, parallel, or both series and parallel.

17. An apparatus for testing a light-emitting device comprising a plurality of light-emitting diodes comprising:

a current source to provide a current to drive the plurality of the light-emitting diodes;

an image receiving device for receiving an image of the light-emitting device in the driven state;

a processing unit for determining a luminous intensity of each of the light-emitting diodes with the image; and

a comparing unit to compare the luminous intensity of each of the light-emitting diodes with a pre-determined luminous intensity for determining whether each of the light-emitting diodes is a defective light-emitting diode or not.

18. The apparatus as claimed in claim 17 , wherein the image receiving device further comprises a filter for filtering off a specific range of the wave length of light.