Organic light emitting display device and method of fabricating the same

Abstract

An apparatus for providing a driving signal to an organic light emitting diode in an image display device includes gate lines for transferring previous and current gate signals, respectively, in a sequential process for providing the driving signal to the organic light emitting diode, a data line for transferring a data signal for displaying images on the image display device, a first switching transistor including a conduction path for transferring the data signal from the data line in response to the current gate signal; a second switching transistor including a conduction path for transferring a reference signal externally supplied in response to the previous gate signal, a third switching transistor including a conduction path for transferring the data signal provided from the first switching transistor in response to a state of the second switching transistor, and a fourth switching transistor including a conduction path for receiving a bias voltage and generating the driving signal to the organic light emitting diode in response to one of the reference signal from the second switching transistor and the data signal from the third switching transistor. The third and fourth switching transistors have switching characteristics substantially identical to each other.

1 - 35 . (canceled) 
   
   
       34 . The organic light emitting display device of claim  26 , wherein the driving, first and second switching transistors are thin film transistors each having a source and a drain forming a conduction path and a gate receiving a gate signal to control the conduction path. 
   
   
       35 . A method for fabricating a semiconductor device for providing a pixel driving signal in an organic light emitting display device, comprising:
 providing an insulation substrate;   forming on the insulation substrate a first amorphous silicon thin film transistor for providing the pixel driving signal to an organic light emitting diode;   forming on the insulation substrate a second amorphous silicon thin film transistor for transferring a data signal to control a switching function of the first amorphous silicon thin film transistor;   crystallizing the first and second amorphous silicon thin film transistors by performing a laser scan on the first and second amorphous silicon thin film transistor; and   transforming the first and second amorphous silicon thin film transistor into first and second polysilicon thin film transistors, respectively, by consummating the crystallizing step,   wherein the first and second polysilicon thin film transistors have characteristics substantially identical to each other.   
   
   
       36 . The method of  claim 35 , wherein the forming the first amorphous silicon thin film transistor includes forming a gate electrode of the first amorphous silicon thin film transistor in a direction substantially parallel to a laser scan direction, and the forming the second amorphous silicon thin film transistor includes forming a gate electrode of the second amorphous silicon thin film transistor in the direction substantially parallel to the laser scan direction. 
   
   
       37 . The method of  claim 36 , wherein the forming the first amorphous silicon thin film transistor includes forming source and drain electrodes of the first amorphous silicon thin film transistor in a collinear direction substantially perpendicular to the laser scan direction, and the second amorphous silicon thin film transistor includes forming source and drain electrodes of the second amorphous silicon thin film transistor in the collinear direction substantially perpendicular to the laser scan direction. 
   
   
       38 . The method of  claim 35 , wherein the forming the first amorphous silicon thin film transistor includes forming a gate electrode of the first amorphous silicon thin film transistor in a collinear direction substantially perpendicular to a laser scan direction, and the forming the second amorphous silicon thin film transistor includes forming a gate electrode of the second amorphous silicon thin film transistor in the collinear direction substantially perpendicular to the laser scan direction. 
   
   
       39 . The method of  claim 38 , wherein the forming the first amorphous silicon thin film transistor includes forming source and drain electrodes of the first amorphous silicon thin film transistor in a direction substantially parallel to the laser scan direction, and the second amorphous silicon thin film transistor includes forming source and drain electrodes of the second amorphous silicon thin film transistor in the direction substantially parallel to the laser scan direction. 
   
   
       40 . The method of  claim 35 , further including forming a mask that forms a laser beam pattern on the insulation substrate. 
   
   
       41 . The method of  claim 40 , further including exposing a pattern of the mask to the insulation substrate by zooming-out the pattern.