Pixel Circuit, Light Emitting Display Device, and Driving Method Thereof

A light emitting display device comprising:

• a display panel that includes a plurality of data lines, a plurality of gate lines, a plurality of emission lines, and a plurality of pixels which are connected to the plurality of data lines, the plurality of gate lines, and the plurality of emission lines;
• a data driver that supplies a data signal to the plurality of data lines;
• a gate driver that supplies a gate signal to the plurality of gate lines and supplies an emission signal to the plurality of emission lines;
• and
• a timing controller that controls the data driver and the gate driver,
• wherein each pixel includes:
• a first transistor having:
• a first electrode connected to a first node which is coupled to a first power supply line supplying a first source voltage,
• a second electrode connected to a second node, and
• a gate electrode connected to a third node,
• a second transistor having:
• a first electrode connected to the first node,
• a second electrode connected to the third node, and
• a gate electrode connected to a first gate line,
• a light emitting diode coupled to the first transistor,
• a first capacitor having:
• a first electrode connected to the third node, and
• a second electrode connected to a conductive line and an anode electrode of the light emitting diode, the conductive line coupled to a second power supply line supplying an initialization voltage, and
• a second capacitor having:
• a first electrode connected to the third node, and
• a second electrode connected to a constant voltage source which supplies a DC voltage.

A light emitting display device comprising:

• a substrate;
• a semiconductor layer that is disposed on the substrate;
• a gate insulating film that is disposed on the semiconductor layer;
• a gate electrode that is disposed to overlap the semiconductor layer on the gate insulating film;
• an interlayer insulating film that is disposed on the gate electrode;
• a first power supply line that is disposed on the interlay insulating film and supplies a first source voltage, at least a part of the first power supply line overlapping the gate electrode;
• a source electrode that is disposed on the interlayer insulating film and is in contact with the semiconductor layer via a first contact hole;
• a drain electrode that is disposed on the interlayer insulating film and is in contact with the semiconductor layer via a second contact hole;
• a protection layer that is disposed on the first power supply line, the source electrode, and the drain electrode;
• and
• a conductive film that is disposed on the protection layer, at least a part of the conductive film overlapping the gate electrode.

A method of driving a light emitting display device including a plurality of pixels, in each of the pixels, a drive current is supplied to a light emitting diode in response to a voltage which is applied to a gate electrode of a first transistor, the method comprising:

• initializing the pixel;
• writing a data voltage to the pixel;
• sampling a threshold voltage of the first transistor;
• and
• supplying the drive current to the light emitting diode,
• wherein the gate electrode of the first transistor is capacitively coupled to a constant voltage source that supplies a DC voltage.