Light-emitting device

Abstract

A-light-emitting device which realizes a high aperture ratio and in which the quality of image is little affected by the variation in the characteristics of TFTs. The channel length of the driving TFTs is selected to be very larger than the channel width of the driving TFTs to improve current characteristics in the saturated region, and a high VGS is applied to the driving TFTs to obtain a desired drain current. Therefore, the drain currents of the driving TFTs are little affected by the variation in the threshold voltage. In laying out the pixels, further, wiring is arranged under the partitioning wall and the driving TFTs are arranged under the wiring in order to avoid a decrease in the aperture ratio despite of an increase in the size of the driving TFT.

1 . (canceled) 
     
     
         2 . A display device comprising:
 a first transistor including a first semiconductor layer, the first transistor being a driving transistor;   a current supply line electrically connected to the driving transistor;   a light-emitting element electrically connected to the first transistor;   a second transistor including a second semiconductor layer, the second transistor electrically connected to a source signal line and a first gate signal line; and   a third transistor including the second semiconductor layer, the third transistor electrically connected to a second gate signal line,   wherein a gate electrode of the first transistor is arranged under and overlaps with the current supply line,   wherein the first semiconductor layer is arranged under and overlaps with the current supply line,   wherein the first semiconductor layer includes a channel-forming region of the first transistor in a shape of a meandering shape, and   wherein the second semiconductor layer includes channel-forming regions of the second transistor and the third transistor and is arranged between the first gate signal line and the second gate signal line.   
     
     
         3 . The display device according to  claim 2 ,
 wherein the first gate signal line and the second gate signal line extend in a first direction,   wherein the source signal line extends in a second direction,   wherein the first gate signal line and the source signal line intersect with each other,   wherein the second gate signal line and the source signal line intersect with each other, and   wherein a first length of the gate electrode along the first direction is shorter than a second length of the gate electrode along the second direction.   
     
     
         4 . The display device according to  claim 2 , wherein the current supply line extends in the same direction as the source signal line. 
     
     
         5 . The display device according to  claim 2 , further comprising a capacitor;
 wherein the capacitor overlaps with the channel-forming region of the first transistor, and   wherein the capacitor includes the gate electrode of the first transistor as one electrode of the capacitor.   
     
     
         6 . An electronic device comprising the display device according to  claim 2 .