Organic light emitting display device using an adjustable power source voltage and driving method thereof

Patent metadata

Field	Value
Publication number	US-9368060-B2
Application number	US-201314040925-A
Country	US
Kind code	B2
Filing date	Sep 30, 2013
Priority date	Feb 27, 2013
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A power system for an organic light emitting diode (OLED) display includes a power supplier and a power source controller. The power supplier respectively supplies a first power source voltage and a second power source voltage to first and second power source voltage application lines. The power source controller calculates a reference power source voltage corresponding to a maximum average grayscale using a distribution for each grayscale of first to third image data, models each voltage drop of the first and second power source voltages for first to third subpixels, and reflects the voltage drop to the reference power source voltage to change the second power source voltage.

First claim

What is claimed is:

1. An organic light emitting diode (OLED) display including a plurality of data lines, a plurality of scan lines, and a plurality of pixels connected to a corresponding data line, a corresponding scan line, a first power source voltage application line, and a second power source voltage application line, wherein the plurality of pixels respectively include first to third subpixels emitting light according to first image data for a first color, second image data for a second color, and third image data for a third color, comprising:
a power supplier respectively to supply a first power source voltage and a second power source voltage to the first and second power source voltage application lines; and
a power source controller to calculate a reference power source voltage corresponding to a maximum average grayscale by using a distribution for each grayscale of the first to third image data, to calculate a ratio of a current that is a sum of second to fourth currents flowing respectively through the first to third subpixels when the first to third subpixels respectively emit light having a first grayscale value to a first current flowing through the first to third subpixels when the first to third subpixels simultaneously emit light with the first grayscale value, to model a first voltage drop of the first power source voltage and a second voltage drop of the second power source voltage for the first to third subpixels and to reflect the first and second voltage drops to the reference power source voltage to change the second power source voltage.

2. The organic light emitting diode (OLED) display of claim 1 , wherein the power source controller includes:
a histogram analyzer to divide a total grayscale number of the first to third image data into a plurality of regions and calculates an average grayscale value for each region for the first to third image data;
a reference voltage setter to calculate a saturation voltage value of the second power source voltage respectively corresponding to the average grayscale value and sets a lowest value among saturation voltage values as the reference power source voltage;
a voltage drop calculator to add currents corresponding to remaining average grayscale values, excluding the average grayscale value that is set to be the reference power source voltage, to calculate a compensation current and generates an equivalent model of the first to third subpixels to calculate a resistance value of an equivalent resistor, thereby calculating the first and second voltage drops of the first and the second power source voltages; and
a power source voltage calculator to reflect the first and second voltage drops to the reference power source voltage to calculate a predicted value of the second power source voltage.

3. The organic light emitting diode (OLED) display of claim 2 , further comprising a lookup table storing an average grayscale value for each region for the first to third image data.

4. The organic light emitting diode (OLED) display of claim 2 , further comprising a lookup table storing the saturation voltage values of the second power source voltage for each grayscale for the first to third image data.

5. The organic light emitting diode (OLED) display of claim 2 , further comprising a third lookup table storing a current value for each grayscale for the first to third image data.

6. The organic light emitting diode (OLED) display of claim 2 , wherein
the equivalent model includes:
a first equivalent organic light emitting diode (OLED) corresponding to a first OLED of the first subpixel, the first OLED emitting light of the first color according to the first image data;
a second equivalent organic light emitting diode (OLED) corresponding to a second OLED of the second subpixel, the second OLED emitting light of the second color according to the second image data;
a third equivalent organic light emitting diode (OLED) corresponding to a third OLED of the third subpixel, the third OLED emitting light of the third color according to the third image data;
first to third equivalent driving transistors corresponding to first to third driving transistors of the first to third subpixels, respectively, the first to third driving transistors respectively driving the first to third organic light emitting diodes (OLED);
a top equivalent resistor corresponding to a resistor of the first power source voltage application line, the top equivalent resistor commonly connected to the first to third equivalent driving transistors; and
a bottom equivalent resistor corresponding to a resistor of the second power source voltage application line, the bottom equivalent resistor commonly connected to the first to third equivalent organic light emitting diodes (OLED).

7. The organic light emitting diode (OLED) display of claim 6 , wherein
the voltage drop calculator calculates the ratio of the current that is a sum of the second to fourth currents flowing when the first to third organic light emitting diodes (OLED) respectively emit light having the first grayscale value to the first current flowing when the first to third organic light emitting diodes (OLED) simultaneously emit light with the first grayscale value as a top voltage drop ratio by the top equivalent resistor.

8. The organic light emitting diode (OLED) display of claim 7 , wherein
the voltage drop calculator calculates the first to third driving currents by multiplying the top voltage drop ratio by the second to fourth currents and calculates a resistance value of the bottom equivalent resistor using the saturation voltage values of the second power source voltage respectively corresponding to the first to third driving currents, and the first to third driving currents.

9. The organic light emitting diode (OLED) display of claim 8 , wherein
the voltage drop calculator divides a voltage value that is equivalent to the saturation voltage value of the second power source voltage corresponding to the first grayscale subtracted from a highest saturation voltage value among the saturation voltage values of the second power source voltage respectively corresponding to the first to third driving currents by a sum of the remaining driving currents excluding the driving current corresponding to the highest saturation voltage value among the first to third driving currents to calculate a resistance value of the bottom equivalent resistor.

10. The organic light emitting diode (OLED) display of claim 8 , wherein
the voltage drop calculator multiples the compensation current and the resistance value of the bottom equivalent resistor to calculate the second voltage drop by the bottom equivalent resistor.

11. The organic light emitting diode (OLED) display of claim 10 , wherein
the voltage drop calculator calculates a total voltage drop value by multiplying the top voltage drop ratio by the second voltage drop by the bottom equivalent resistor.

12. The organic light emitting diode (OLED) display of claim 11 , wherein
the voltage drop calculator calculates a voltage that is decreased by the total voltage drop value to the reference power source voltage as a predicted value of the second power source voltage.

13. A method of driving an organic light emitting diode (OLED) display including a plurality of data lines, a plurality of scan lines, and a plurality of pixels connected to a corresponding data line, a corresponding scan line, a first power source voltage application line, and a second power source voltage application line, wherein the plurality of pixels respectively include first to third subpixels emitting light according to first image data display

Assignees

• Samsung Display Co Ltd

Inventors

• Chae Se-Byung
• Lee Wook
• Shin Jeong-Hwan

Classifications

• G09G2360/16

  Calculation or use of calculated indices related to luminance levels in display data · CPC title

• G09G2330/02

  Details of power systems and of start or stop of display operation · CPC title

• G09G3/3696

  Generation of voltages supplied to electrode drivers · CPC title

• G09G2320/0233

  Improving the luminance or brightness uniformity across the screen · CPC title

• G09G3/3225 Primary

  using an active matrix · CPC title