Organic light emitting display with compensation for transistor threshold variation
View Patent ↗An organic light emitting display is disclosed. The display includes a scan line, a data line, and a pixel coupled to the scan line and the data line. The pixel is configured to at least partially compensate for transistor threshold variation and for IR-drop in a power supply line, where the pixel includes no more than three transistors and no more than two capacitors.
1. An organic light emitting display, comprising:
a scan line;
a data line; and
a pixel coupled to the scan line and the data line;
wherein the pixel comprises:
a first switching transistor including a control electrode coupled to the scan line, and a first electrode coupled to the data line;
a driving transistor connected between a first power supply line and a second power supply line, the driving transistor including a control electrode coupled to the first switching transistor;
a first storage capacitor connected to the first switching transistor, the first power supply line and the driving transistor;
a second switching transistor connected between the first power supply line and the driving transistor, the second switching transistor comprising a control electrode coupled to an emission control line;
a second storage capacitor connected to the first switching transistor and connected to the first storage capacitor and connected to the second switching transistor and connected to the driving transistor; and
an organic light emitting diode coupled between the driving transistor and the second power supply line,
wherein the second storage capacitor is not a parasitic capacitor of the driving transistor.
2. The organic light emitting display as claimed in claim 1 , wherein the first switching transistor includes an electrode coupled to the control electrode of the driving transistor.
3. The organic light emitting display as claimed in claim 1 , wherein the first switching transistor is configured to transfer data from the data line to the driving transistor while the control electrode of the first switching transistor receives a scan signal from the scan line.
4. The organic light emitting display as claimed in claim 1 , wherein the control electrode of the driving transistor is coupled to the first switching transistor, the driving transistor including a first electrode coupled to the second switching transistor, and a second electrode coupled to an anode of the organic light emitting diode.
5. The organic light emitting display as claimed in claim 1 , wherein the driving transistor is configured to control a driving current from the first power supply line according to a data signal at the control electrode of the driving transistor.
6. The organic light emitting display as claimed in claim 1 , wherein the first storage capacitor includes a first electrode coupled to the first power supply line, and a second electrode coupled to the first switching transistor and the control electrode of the driving transistor.
7. The organic light emitting display as claimed in claim 1 , wherein the first storage capacitor includes a first electrode coupled to the first power supply line and a second electrode coupled to the second storage capacitor.
8. The organic light emitting display as claimed in claim 1 , wherein the control electrode of the second switching transistor is coupled to the emission control line, and the second switching transistor includes a first electrode coupled to the first power supply line, and a second electrode coupled to the driving transistor.
9. The organic light emitting display as claimed in claim 1 , wherein the control electrode of the second switching transistor is coupled to the emission control line, and the second switching transistor includes a first electrode coupled to the first power supply line, and a second electrode coupled to the second storage capacitor.
10. The organic light emitting display as claimed in claim 1 , wherein the first electrode of the second storage capacitor is coupled to the second switching transistor and the driving transistor, and the second electrode of the second storage capacitor is coupled to the first storage capacitor, the first switching transistor, and the driving transistor.
11. The organic light emitting display as claimed in claim 1 , wherein the second storage capacitor is coupled between the control electrode of the driving transistor and a first electrode of the driving transistor.
12. The organic light emitting display as claimed in claim 1 , wherein the organic light emitting diode includes an anode coupled to the driving transistor and a cathode coupled to the second power supply line.
13. The organic light emitting display as claimed in claim 1 , wherein a second power supply voltage of the second power supply line is lower than a first power supply voltage of the first power supply line.
14. The organic light emitting display as claimed in claim 1 , wherein the second power supply voltage of the second power supply line is a ground voltage.
15. The organic light emitting display as claimed in claim 1 , wherein during a period for displaying one frame, while the first switching transistor and the second switching transistor are turned on, a data voltage from the data line is applied to the first storage capacitor, the second storage capacitor, and the control electrode of the driving transistor, after which the first power supply voltage from the first power supply line is applied to the first storage capacitor and to the second storage capacitor.
16. The organic light emitting display as claimed in claim 1 , wherein during a period for displaying one frame, while the first switching transistor is turned on, and the second switching transistor is turned off, a data voltage from the data line is applied to the first storage capacitor, the second storage capacitor, and the control electrode of the driving transistor, after which the first power supply voltage from the first power supply line is applied to the first storage capacitor.
17. The organic light emitting display as claimed in claim 1 , wherein during a period for displaying one frame, while the first switching transistor is turned off, and the second switching transistor is turned on, the first power supply line, the driving transistor, and the organic light emitting diode are coupled one another, and a current flows from the anode of the organic light emitting diode to the cathode of the organic light emitting diode.
18. The organic light emitting display as claimed in claim 1 , wherein an emission control switching transistor is included between the driving transistor and the organic light emitting diode.
19. The organic light emitting display as claimed in claim 18 , wherein the emission control switching transistor includes a control electrode coupled to the emission control line, a first electrode coupled to the second electrode of the driving transistor, and a second electrode coupled to the anode of the organic light emitting diode.