Patent ID: 7855701

Claim:
An organic electro-luminescence device, comprising: a light-emitting device in a pixel for emitting light; a data line for providing a data voltage; a driving transistor connected to the light emitting device, wherein when the driving transistor is turned on to drive the light-emitting device, a driving voltage applied to the light emitting device reaches a value of a difference between a supply voltage and the data voltage; a power line to supply the supply voltage; a capacitor between the data line and a gate of the driving transistor for storing a voltage of a difference between the data voltage and a threshold voltage of the driving transistor; a first switching device between the data line and the capacitor; a second switching device between the gate of the driving transistor and a drain of the driving transistor; and a third switching device between one of an anode and a cathode of the light-emitting device and a node between the first switching device and the capacitor, wherein the supply voltage is supplied via the power line to an anode of the light-emitting device, wherein the driving transistor includes a negative gain circuit in which the drain of the driving transistor is connected to the gate of the driving transistor by the second switching device, wherein the third switching device is operated by a logic level opposite to the logic level supplied to the first and second switching devices, wherein the driving transistor and the capacitor constitutes a buffer circuit configured to buffer a driving voltage applied to the inside of the pixel, wherein each of the first switching device, the second switching device and the third switching device is a thin film transistor of the type which is identical, wherein the gate and the drain of the driving transistor is equal when the first and second switching devices are turned on, and the third switching device is turned off, the capacitor is charged with the difference between the data voltage and a voltage of the gate, wherein the voltage of the drain of the driving transistor adds the charged voltage of the capacitor to the threshold voltage when the first and second switching devices are turned off, and the third switching device is turned on, wherein the first and second switching devices are operated in response to a first scan signal applied from a first gate line among a plurality of gate lines, the third switching device is operated by a second scan signal applied from a next gate line of the first gate line, and wherein the second scan signal has a period of a low level when the first scan signal has a period of a high level, the second scan signal has a period of a high level when the first scan signal has a period of a low level.