PIXEL

• US 20120280634A1
• Filed: 06/08/2011
• Published: 11/08/2012
• Est. Priority Date: 05/02/2011
• Status: Active Grant

• Current Assignee: University-Industry Foundation Yonsei University
• Original Assignee: University-Industry Foundation Yonsei University
• Inventors: Kwon, Oh-Kyong
• Granted Patent: US 8,674,907 B2
• Time in Patent Office: Days
• US Class Current: 315/240
• CPC Class Codes: G09G 2300/0871 with level shifting
• CPC Class Codes: G09G 2300/0885 Pixel comprising a non-linear two-terminal element alone in series with each display pixel element
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

Disclosed is a pixel capable of finely controlling the amount of current and increasing the voltage range of a data signal. A pixel includes an organic light emitting diode, a first transistor, a storage capacitor, a load and an amplifier. The first transistor is coupled between a scan line and a data line, and supplies a data signal supplied to the data line to a first node when a scan signal is supplied to the scan line. The storage capacitor is coupled between the first node and a first power source, and charges a voltage corresponding to the data signal. The load is coupled between the organic light emitting diode and the first power source. The amplifier controls a voltage applied to the load corresponding to the voltage charged in the storage capacitor.

Claims

1. A pixel comprising:

an organic light emitting diode;

a first transistor coupled between a scan line and a data line, the first transistor supplying a data signal supplied to the data line to a first node when a scan signal is supplied to the scan line;

a storage capacitor coupled between the first node and a first power source, the storage capacitor charging a voltage corresponding to the data signal;

a load coupled between the organic light emitting diode and the first power source; and

an amplifier that controls a voltage applied to the load corresponding to the voltage charged in the storage capacitor.

2. The pixel according to claim 1, wherein the amplifier is a second transistor having a gate electrode coupled to the first node, a first electrode coupled to the load and a second electrode coupled to the organic light emitting diode.

3. The pixel according to claim 2, wherein the load is a diode-coupled third transistor.

4. The pixel according to claim 3, wherein gate and second electrodes of the third transistor are coupled to the first electrode of the second transistor, and a first electrode of the third transistor is coupled to the first power source.

5. The pixel according to claim 4, wherein the second transistor controls a voltage applied to the gate and second electrodes of the third transistor corresponding to the voltage at the first node.

6. A pixel comprising:

an organic light emitting diode;

a storage capacitor coupled between a first node and a first power source;

a first load coupled between the organic light emitting diode and the first power source;

an amplifier that controls a voltage applied to the first load corresponding to the voltage applied to the first node;

a bias circuit that controls the voltage applied to the first node corresponding to a data signal supplied from a data line; and

a first transistor coupled between the bias circuit and the first node, the first transistor being turned on when a first scan signal is supplied to a first scan line,

wherein the voltage applied to the first node is set to have a voltage range narrower than that of the data signal by the bias circuit.

7. The pixel according to claim 6, wherein the amplifier is a second transistor having a gate electrode coupled to the first node, a first electrode coupled to the first load and a second electrode coupled to the organic light emitting diode.

8. The pixel according to claim 7, wherein the first load is a third transistor having gate and second electrodes coupled to the first electrode of the second transistor and a first electrode coupled to the first power source.

9. The pixel according to claim 6, wherein the bias circuit comprises:

a second load coupled between the first power source and a third node; and

a variable load coupled between the third node and a third power source lower than the first power source, the variable load having resistance changed corresponding to the data signal.

10. The pixel according to claim 9, further comprising a sixth transistor having a first electrode coupled to the variable load and a second electrode coupled to the third power source, the sixth transistor being turned on when a second scan signal is supplied to a second scan line.

11. The pixel according to claim 10, wherein the sixth transistor is turned on before the first transistor is turned on, and the sixth transistor is turned off after the first transistor is turned off.

12. The pixel according to claim 10, wherein the second load is a fourth transistor having a first electrode coupled to the first power source, a second electrode coupled to the third node and a gate electrode coupled to the first electrode of the sixth transistor.

13. The pixel according to claim 12, wherein the variable load is a fifth transistor having a first electrode coupled to the third node, a second electrode coupled to the first electrode of the sixth transistor and a gate electrode coupled to the data line.

14. The pixel according to claim 13, wherein the fourth transistor is formed to have a resistance lower than that of the fifth transistor.

15. The pixel according to claim 9, wherein the first transistor is coupled between the third node and the first node.

16. A pixel comprising:

an organic light emitting diode;

a current source that generates current varied depending on a difference between a predetermined first voltage and a variable second voltage and supplies the generated current to the organic light emitting diode; and

a bias circuit that outputs the second voltage depending on an input data voltage and controls a variable amplitude of the second voltage with respect to the amplitude of the input data voltage using a variable load.

17. The pixel according to claim 16, wherein the variable load outputs the second voltage while changing resistance corresponding to the input data voltage.