Organic light emitting display and driving method thereof

• US 20080158218A1
• Filed: 09/04/2007
• Published: 07/03/2008
• Est. Priority Date: 01/03/2007
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Group)
• Original Assignee: Samsung Mobile Display Company Limited (Samsung Group)
• Inventors: Kim, Do-ik
• Granted Patent: US 7,986,317 B2
• Time in Patent Office: Days
• US Class Current: 345/212
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/3225 using an active matrix

Abstract

An display and a driving method thereof are capable of displaying images of desired luminance. The display includes a scan driver connected to scan lines, a data driver connected to data lines, pixels connected to the scan lines and the data lines, the pixels being adapted to generate light while supplying an electric current from a first power source to a second power source, a power source unit for generating the first power source, and a compensating unit adapted to control a voltage value of the first power source.

Claims

1. A organic light emitting display, comprising:

a scan driver connected to scan lines;

a data driver connected to data lines;

pixels connected to the scan lines and the data lines, the pixels being adapted to generate light while applying an electric current from a first power source to a second power source through an organic light emitting diode;

a power source unit adapted to generate the first power source; and

a compensating unit adapted to control a voltage value of the first power source.

2. The organic light emitting display as claimed in claim 1, wherein the compensating unit is adapted to control the voltage of the first power source according to an amount of the electric current applied to the pixels.

3. The organic light emitting display as claimed in claim 2, wherein the compensating unit is adapted to control the voltage of the first power source at least once when the first and second power sources are applied to the display.

4. The organic light emitting display as claimed in claim 3, wherein the compensating unit includes:

a resistor between the power source unit and the pixels;

an amplifier adapted to amplify a voltage across the resistor;

a reference voltage generator adapted to generate a reference voltage;

a comparator adapted to compare the amplified voltage with the reference voltage;

a counter adapted to generate a counter signal counting up or down a count according to a comparison result of the comparator; and

a controller adapted to supply a feedback signal to the power source unit, the feedback signal being generated in accordance with the counter signal.

5. The organic light emitting display as claimed in claim 4, wherein the compensating unit is adapted to apply the reference voltage across the resistor when the pixels emit full white light during an initial drive, and to set the reference voltage to be substantially identical to the voltage amplified by the amplifier.

6. The organic light emitting display as claimed in claim 4, wherein the comparator is adapted to generate the counter signal so that the amplified voltage from the amplifier becomes substantially identical to the reference voltage.

7. The organic light emitting display as claimed in claim 4, wherein the compensating unit includes:

a temperature sensor adapted to measure a temperature of a panel; and

a look-up table adapted to store control values corresponding to the temperature measured by the temperature sensor.

8. The organic light emitting display as claimed in claim 7, wherein the control values are set to be reduced as the temperature is increased.

9. The organic light emitting display as claimed in claim 7, wherein the controller is adapted to extract a control value from the look-up table according to the temperature, and the controller is adapted to sum up the extracted control value and the counter signal to generate the compensating signal.

10. The organic light emitting display as claimed in claim 4, wherein the power source unit is adapted to control a voltage of the first power source according to the feedback signal.

11. The organic light emitting display as claimed in claim 2, wherein the power source unit includes:

a red power source unit adapted to generate a first red power source supplied to red pixels;

a green power source unit adapted to generate a first green power source supplied to green pixels; and

a blue power source unit adapted to generate a first blue power source supplied to blue pixels.

12. The organic light emitting display as claimed in claim 11, wherein the compensating unit includes:

a red compensating unit adapted to control the voltage of the first red power source;

a green compensating unit adapted to control the voltage of the first green power source; and

a blue compensating unit adapted to control the voltage of the first blue power source, when a power source is input to the organic light emitting display.

13. The organic light emitting display as claimed in claim 12, wherein each of the red compensating unit, the green compensating unit, and the blue compensating unit includes:

a resistor between the red power source unit, the green power source unit, or the blue power source unit and the pixels;

an amplifier adapted to amplify a voltage across the resistor;

a reference voltage generator adapted to generate a reference voltage;

a comparator adapted to compare the amplified voltage from the amplifier with the reference voltage;

a counter adapted to generate a counter signal counting up or down a count according the comparison result of the comparator;

a controller adapted to transfer the counter signal to a digital-to-analog converter as a compensating signal; and

the digital-to-analog converter adapted to convert the compensating signal into an analog signal.

14. The organic light emitting display as claimed in claim 13, wherein the comparator is adapted to generate the counter signal so that the amplified voltage from the amplifier becomes substantially identical to the reference voltage.

15. The organic light emitting display as claimed in claim 13, wherein the compensating unit includes:

a temperature sensor adapted to measure a temperature of a panel; and

a look-up table installed in each of the red compensating unit, the green compensating unit, and the blue compensating unit, the look-up table being adapted to store control values corresponding to the temperature measured by the temperature sensor.

16. The organic light emitting display as claimed in claim 15, wherein the compensating unit is adapted to set the control values to be reduced as the temperature is increased.

17. The organic light emitting display as claimed in claim 16, wherein the controller is adapted to extract the control values from the look-up table according to the temperature, and to sum up the extracted control values and the counter signal to generate the compensating signal.

18. A method for driving an organic light emitting display including pixels for generating light using an electric current from a first source to a second power source through an organic light emitting diode, the method comprising:

(i) generating the first power source by a power source unit;

(ii) amplifying a voltage across a resistor installed between the first power source and the pixels;

(iii) comparing the amplified voltage with a reference voltage, and generating a counter signal according to the comparison result so that the amplified voltage becomes identical with the reference voltage;

(iv) transferring the counter signal to a digital-analog converter as a compensating signal;

(v) supplying the compensating signal converted into a digital signal by the digital-analog converter to the power source unit; and

(vi) controlling a voltage of the first power source by the power source unit according to the compensating signal.

19. The method as claimed in claim 18, wherein the reference voltage is set to be substantially the same voltage as the amplified voltage during an initial drive.

20. The method as claimed in claim 18, further comprising:

measuring a temperature of a panel; and

extracting a control value stored in a look-up table corresponding to the measured temperature of the panel; and

summing the control value and the counter signal to generate the compensating signal.

21. The method as claimed in claim 20, wherein the control value is reduced as the temperature is increased.