Patent ID: 7528809

Claim:
An organic light emitting display comprising: a first transistor having a gate electrode connected to a first selection signal, a source electrode connected to a data signal, and a drain electrode connected to a second node; a second transistor having a gate electrode connected to the first selection signal, a source electrode connected to a power voltage, and a drain electrode connected to a first node; a third transistor having a gate electrode connected to a second selection signal, a source electrode connected to a reference voltage, and a drain electrode connected to the second node; a capacitor connected between the first node and the second node; and a fourth transistor having a gate electrode connected to the first node, a source electrode connected to the power voltage, and a drain electrode connected to an organic light emitting diode (OLED), wherein during a first period, the data signal is supplied to the second node by switching the first transistor and the power voltage is supplied to the first node by switching the second transistor, and during a second period, the reference voltage is supplied to the second node by switching the third transistor such that a voltage relating to the power voltage, the data voltage and the reference voltage is charged at the first node, and wherein the reference voltage is different from the power voltage.