Organic light emitting display device and driving method of the same

An OLED display device comprising:

• a plurality of pixels each including an organic light emitting diode and a pixel driving circuit that drives the organic light emitting diode,
• wherein the pixel driving circuit includes:
• a driving TFT configured to control driving of the organic light emitting diode and including a gate node as a first node, a source node as a second node, and a drain node as a fourth node;
• first, second, and third switching TFTs electrically connected to the driving TFT;
• first and second storage capacitors configured to store a voltage to be applied to the driving TFT;
• and
• a coupling capacitor connected between a third node as a gate node of the third switching TFT and the fourth node,
• wherein a voltage of the fourth node is bootstrapped by the coupling capacitor when a voltage of the third node is in a high stage, and
• the pixel driving circuit operates in a period divided into:
• an initialization period in which a reference voltage is supplied to the first node and an initialization voltage is supplied to the second node;
• a sampling period in which a voltage higher than the reference voltage is supplied to the first node and the voltage higher than the reference voltage minus a threshold voltage is supplied to the second node by the coupling capacitor;
• a programming period in which a data voltage is supplied to the first node and a voltage of the second node is changed by the data voltage;
• and
• an emission period in which a delay of a current involved in emission of the organic light emitting diode is minimized by a voltage bootstrapped to the source node of the driving TFT.