Patent ID: 7812799

Claim:
A display device, comprising: an insulating substrate; a switching thin film transistor and a driving thin film transistor formed on the insulating substrate, the driving thin film transistor including a semiconductor layer; a first electrode electrically connected with the driving thin film transistor; a light emitting layer formed on the first electrode; a second electrode which supplies a common voltage at a predetermined level to the light emitting layer; and a data driver which supplies a data voltage to the switching thin film transistor, the data voltage ranging from a first voltage to a second voltage and wherein the first voltage, the second voltage and the common voltage satisfy the following equations: First voltage−common voltage−voltage dropped by light emitting layer=black voltage±|black voltage−white voltage|*0.1 [Equation 1] Second voltage−common voltage−voltage dropped by light emitting layer=white voltage±|black voltage−white voltage|*0.1, [Equation 2] wherein the black voltage refers to a gate-source voltage (V GS ) that expresses the lowest gradation and the white voltage refers to a gate-source voltage V GS that expresses the highest gradation.