| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problems that luminance is made hardly degradable in spite of deterioration of an EL element by operating a driving TFT in a saturation region, but by so doing, an increase in voltage, power consumption and heat generation result and if the TFT is driven in the saturation region, luminance unevenness is caused due to the variation in the driving TFT. <P>SOLUTION: A TFT of a high current capacity is used for a high gradation and a TFT of a low current capacity is used for a low gradation as the driving TFT. Since a TFT having a high current capacity can supply a large current even at lower Vgs and therefore the linear region hardly occurs in spite of low Vds. Consequently, even if the EL element is deteriorated, the luminance degradation hardly occurs and the driving with a low voltage is made possible. The current is supplied by applying a higher Vgs to the TFT of the low current capacity. The high Vgs can reduce the influence of the variation in the characteristics of the TFT, particularly the variation in Vth. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
