Method of driving a light emitting device

Abstract

The present invention is characterized in that a transistor with its L/W set to 10 or larger is employed, and that |V DS | of the transistor is set equal to or larger than 1 V and equal to or less than |V GS −V th |. The transistor is used as a resistor so that the resistance of a light emitting element can be held by the transistor. This slows down an increase in internal resistance of the light emitting element and the resultant current value reduction. Accordingly, a change with time in light emission luminance is reduced and the reliability is improved.

What is claimed is: 
     
         1 . A method of driving a light emitting device having a light emitting element and a driving transistor, the transistor being connected to the light emitting element, the transistor having a channel width W and a channel length L which satisfy L/W≧10,
 wherein a voltage is applied to a gate electrode of the driving transistor and to a drain electrode or source electrode thereof so that a gate-source voltage V GS , source-drain voltage V DS , and threshold voltage V th  of the driving transistor satisfy 1≦|V DS |≦V GS −V th |.