Organic light emitting display having uniform brightness

1. An organic light emitting display, comprising:

a display panel having a display region and a non-display region;

a plurality of sub pixels defined by perpendicularly intersecting a plurality of gate lines and a plurality of data lines formed in the display region of the display panel; and

a power source supply pad unit provided in the non-display region of the display panel for supplying a power source voltage to the plurality of sub pixels;

wherein a resistance value of sub pixels arranged in a first region adjacent to the power source supply pad unit is higher than a resistance value of sub pixels of a second region which is separated from the power source supply pad unit, with the first region interposed therebetween,

wherein one of the sub pixels comprises:

an organic light emitting diode (OLED) for displaying an image by means of a driving current;

a driving switching element for transmitting the driving current in correspondence to a data signal supplied from a data line to the OLED; and

a power source supply switching element for transmitting a power source voltage of a power source wiring line, electrically coupled to the power source supply pad unit, to the driving switching element in response to an emission control signal of an emission control wiring line, and

wherein an area of a first active layer, which forms the power source supply switching element of the first region, is smaller than an area of a second active layer, which forms the power source supply switching element of the second region.

2. The organic light emitting display as claimed in claim 1 , wherein the sub pixel in the first region has a resistance value corresponding to a reduced voltage of the sub pixels of the second region.

3. The organic light emitting display as claimed in claim 1 , wherein the resistance value of the sub pixels gradually increases from the second region toward the first region adjacent to the power source supply pad unit.

4. The organic light emitting display as claimed in claim 1 , wherein, when a resistance value of a power source wiring line of the first region is R 2 , a resistance value of a power source wiring line of a region adjacent to the first region is R 4 , and resistance values of power source supply switching elements are R 1 , R 3 and R 5 from the first region toward the second region, wherein R 1 >R 3 >R 5 .

5. The organic light emitting display as claimed in claim 4 , wherein R 1 =R 2 +R 3 .

6. The organic light emitting display as claimed in claim 4 , wherein R 1 =R 2 +R 4 +R 5 and R 3 =R 4 +R 5 .

7. The organic light emitting display as claimed in claim 1 , wherein voltages transmitted to the driving switching element for all of the sub pixels are the same.

8. The organic light emitting display as claimed in claim 1 , wherein a resistance value of the power source supply switching element of the first region is higher than a resistance value of the power source supply switching element of the second region.

9. The organic light emitting display as claimed in claim 1 , wherein a resistance value of the power source supply switching element of the first region corresponds to a reduced voltage of the power source supply switching element of the second region.

10. The organic light emitting display as claimed in claim 1 , wherein a resistance value of the power source supply switching element gradually increases from the second region toward the first region adjacent to the power source supply pad unit.

11. The organic light emitting display as claimed in claim 1 , wherein the resistance value of the sub pixel provided in the first region is designed by controlling a resistance value of the power source supply switching element of the sub pixel provided in the first region.