Method of driving a light emitting device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei Yamazaki, Mitsuaki Osame, Jun Koyama
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Abstract
The present invention is characterized in that a transistor with its L/W set to 10 or larger is employed, and that |VDS| of the transistor is set equal to or larger than 1 V and equal to or less than |VGS−Vth|. 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.
Claims1
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 VGS, source-drain voltage VDS, and threshold voltage Vth of the driving transistor satisfy 1≦|VDS|≦VGS−Vth|.
Dependencies are inferred from the claim text.