Micro light emitting diode display panel and driving method thereof

1. A micro light emitting diode display panel, comprising:

a plurality of micro light emitting diodes, wherein each micro light emitting diode comprises an epitaxy layer, a current spreading layer disposed on the epitaxy layer, and an electrode layer formed on the current spreading layer;

a plurality of pixels, wherein one of the pixels comprises a first sub-pixel that comprises two micro light emitting diodes having different areas of the current spreading layers and controlled independently; and

a control element, controlling driving currents to the two micro light emitting diodes according to a gray level of the first sub-pixel, wherein a ratio of the driving current of the micro light emitting diode with larger current spreading layer to the driving current of the micro light emitting diode with smaller current spreading layer increases as the gray level of the first sub-pixel increases, wherein an area ratio of the current spreading layers between the two micro light emitting diodes in the first sub-pixel ranges from 1.2 to 2.

2. The micro light emitting diode display panel according to claim 1 , wherein only the micro light emitting diode with smaller current spreading layer of the first sub-pixel emits light when the first sub-pixel is in minimum gray level, and only the micro light emitting diode with larger current spreading layer of the first sub-pixel emits light when the first sub-pixel is in maximum gray level.

3. The micro light emitting diode display panel according to claim 1 , wherein the first sub-pixel is a green sub-pixel and the two micro light emitting diodes are green micro light emitting diodes.

4. The micro light emitting diode display panel according to claim 1 , wherein each of the micro light emitting diodes further comprises a passivation layer covering the current spreading layer and the epitaxy layer, the passivation layer has an opening exposing the current spreading layer and another opening exposing the epitaxy layer, the electrode layer has a first electrode contacting the epitaxy layer through the opening exposing the epitaxy layer and a second electrode contacting the current spreading layer through the opening exposing the current spreading layer, and the first electrode and the second electrode are isolated.

5. The micro light emitting diode display panel according to claim 4 , wherein the passivation layer covers the side wall of the epitaxy layer.

6. The micro light emitting diode display panel according to claim 1 , wherein the one of the pixels further comprises a second sub-pixel and a third sub-pixel, and the first sub-pixel, the second sub-pixel and the third sub-pixel are with different colors.

7. The micro light emitting diode display panel according to claim 6 , wherein the third sub-pixel comprises one micro light emitting diode, the second sub-pixel comprises two micro light emitting diodes having different areas of the current spreading layers and controlled independently, and the control element controls driving currents to the two micro light emitting diodes of the second sub-pixel according to a gray level of the second sub-pixel, wherein a ratio of the driving current of the micro light emitting diode with larger current spreading layer to the driving current of the micro light emitting diode with smaller current spreading layer increases as the gray level of the second sub-pixel increases.

8. The micro light emitting diode display panel according to claim 6 , wherein the first sub-pixel, the second sub-pixel and the third sub-pixel are respectively a green sub-pixel, a red sub-pixel and a blue sub-pixel, the red sub-pixel comprises two red micro light emitting diodes having different areas of the current spreading layers and controlled independently and with different light wavelengths, the control element controls driving currents to the two red micro light emitting diodes according to a gray level of the red sub-pixel, wherein a ratio of the driving current of the red micro light emitting diode with larger current spreading layer to the driving current of the red micro light emitting diode with smaller current spreading layer increases as the gray level of the red sub-pixel increases, the blue sub-pixel comprises two blue micro light emitting diodes having different areas of the current spreading layers and controlled independently and with different light wavelengths, the control element controls driving currents to the two blue micro light emitting diodes according to a gray level of the blue sub-pixel, wherein a ratio of the driving current of the blue micro light emitting diode with larger current spreading layer to the driving current of the blue micro light emitting diode with smaller current spreading layer increases as the gray level of the blue sub-pixel increases.

9. The micro light emitting diode display panel according to claim 1 , further comprising a plurality of micro-ICs and a substrate, wherein the plurality of micro-ICs and the plurality of micro light emitting diodes are bonded on the substrate, the plurality of micro-ICs are distributed among the plurality of micro light emitting diodes, and each micro-IC is electrically connected to at least two pixels to control the micro light emitting diodes in the at least two pixels.

10. The micro light emitting diode display panel according to claim 9 , wherein a thickness ratio between the micro-IC and the micro light emitting diode ranges from 0.8 to 1.2.

11. The micro light emitting diode display panel according to claim 10 , wherein a thickness of each micro-IC is 5-10 μm and a thickness of each micro light emitting diode is 5-10 μm.