ORGANIC LIGHT EMITTING DIODE DISPLAY DEVICE AND METHOD OF DRIVING THE SAME

• US 20120306947A1
• Filed: 05/31/2012
• Published: 12/06/2012
• Est. Priority Date: 06/01/2011
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: KIM, Hyungjung, Oh, Dong Kyoung, Yu, SangHo, Lee, HyunKi, Lee, MunJun
• Granted Patent: US 8,896,641 B2
• Time in Patent Office: Days
• US Class Current: 345/694
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

An organic light emitting display device includes: a display panel including red, green, blue, and white (RGBW) subpixels; a first data conversion unit configured to convert red, green, and blue (RGB) data signals into RGBW data signals; an average picture level calculation unit configured to calculate an average picture level (APL) for the RGB data signals; a peak luminance controller configured to control luminance of at least one frame by using the APL and a look-up table; and a data compensation unit configured to perform a compensation operation on at least one of the RGB data signals in response to color coordinates of white (W) data signals among the RGBW data signals output from the first data conversion unit being different from a target value.

Claims

1. An organic light emitting display device, comprising:

a display panel comprising red, green, blue, and white (RGBW) subpixels;

a first data conversion unit configured to convert red, green, and blue (RGB) data signals into RGBW data signals;

an average picture level calculation unit configured to calculate an average picture level (APL) for the RGB data signals;

a peak luminance controller configured to control luminance of at least one frame by using the APL and a look-up table; and

a data compensation unit configured to perform a compensation operation on at least one of the RGB data signals in response to color coordinates of white (W) data signals among the RGBW data signals output from the first data conversion unit being different from a target value.

2. The organic light emitting display device of claim 1, wherein the data compensation unit is further configured to:

multiply an arithmetical value, obtained by performing an arithmetical operation on a current APL and a maximum APL, with a difference value corresponding to a difference between a gain of the RGB data signals corresponding to the maximum APL and a gain of the RGB signals corresponding to a target peak luminance APL; and

add the gain of the RGB data signals corresponding to the target peak luminance APL to a result value of the multiplication to calculate correction gain values for the RGB data signals.

3. The organic light emitting display device of claim 2, wherein the data compensation unit is further configured to calculate the correction gain values, based on a gain calculated in accordance with the following equation:

Current gain of data signal selected from among the RGB data signals=(Max APL RGB gain−

Target Peak Lum APL RGB gain)*{(Current APL−

Target Peak Lum APL)/(Max APL−

Target Peak Lum APL)}+Target Peak Lum APL RGB gain+RGB gain weight,

wherein;

Max APL RGB gain is an actual gain measurement value of the RGB data signals corresponding to the maximum APL,

Target Peak Lum APL RGB gain is an actual gain measurement value of the RGB data signals corresponding to the target peak luminance APL,

Current APL is a current APL, Max APL is a maximum APL,

Target Peak Lum APL is a target peak luminance APL, and

RGB gain weight is a gain weight of the RGB data signals.

4. The organic light emitting display device of claim 3, wherein:

the data compensation unit is further configured to apply the gain calculated in accordance with the equation to the green and blue (GB) data signals; and

the gain weights of the RGB data signals are prepared on the basis of actual measurement values obtained by measuring the characteristics of the RGB subpixels on the display panel.

5. The organic light emitting display device of claim 2, wherein the data compensation unit calculates the correction gain value of the green (G) data signal through the following equation:

Current gain of G data signal=(Max APL G gain−

Target Peak Lum APL G gain)*{(Current APL−

Target Peak Lum APL)/(Max APL−

Target Peak Lum APL)}+Target Peak Lum APL G gain,

wherein;

Max APL G gain is an actual gain measurement value of the G data signal corresponding to the maximum APL,

Target Peak Lum APL G gain is an actual gain measurement value of the G data signal corresponding to the target peak luminance APL,

Current APL is a current APL,

Max APL is a maximum APL, and

Target Peak Lum APL is an APL of target peak luminance.

6. The organic light emitting display device of claim 2, wherein the data compensation unit calculates the correction gain value of the blue (B) data signal through the following equation:

Current gain of B data signal=(Max APL B gain−

Target Peak Lum APL B gain)*{(Current APL−

Target Peak Lum APL)/(Max APL−

Target Peak Lum APL)}+Target Peak Lum APL B gain+B gain weight,

wherein;

Max APL B gain is an actual gain measurement value of the B data signal corresponding to the maximum APL,

Target Peak Lum APL B gain is an actual gain measurement value of the B data signal corresponding to the target peak luminance APL,

Current APL is a current APL,

Max APL is a maximum APL,

Target Peak Lum APL is an APL of target peak luminance, and Target Peak Lum APL is an APL of target peak luminance, and

B gain weight is a gain weight of the B data signal.

7. The organic light emitting display device of claim 5, wherein the Target Peak Lum APL is a setter input variable limiting the APL of the target peak luminance.

8. The organic light emitting display device of claim 6, wherein the Target Peak Lum APL is a setter input variable limiting the APL of the target peak luminance.

9. A method of driving an organic light emitting display device, the method comprising:

converting red, green, and blue (RGB) data signals into red, green, blue, and white (RGBW) data signals;

calculating an average picture level (APL) for the RGB data signals;

generating data signals, such that a data signal selected from among the RGB signals is supplied in a display panel in response to color coordinates of the white (W) data signal among the RGBW data signals being different from a target value; and

calculating gain by;

multiplying an arithmetical value, obtained by performing an arithmetical operation on a current APL and a maximum APL, with a value corresponding to a difference between a gain of the RGB data signals corresponding to the maximum APL and a gain of the RGB signals corresponding to a target peak luminance APL; and

adding the gain of the RGB data signals corresponding to the target peak luminance APL to the result value of the multiplication to calculate the correction gain values of the RGB data signals.

10. The method of claim 9, wherein the correction gain values are calculated on the basis of a gain calculated in accordance with the following equation:

Current gain of data signal selected from among the RGB data signals=(Max APL RGB gain−

Target Peak Lum APL RGB gain)*{(Current APL−

Target Peak Lum APL)/(Max APL−

Target Peak Lum APL)}+Target Peak Lum APL RGB gain+RGB gain weight,

wherein;

Max APL RGB gain is an actual gain measurement value of the RGB data signals corresponding to the maximum APL,

Target Peak Lum APL RGB gain is an actual gain measurement value of the RGB data signals corresponding to the target peak luminance APL,

Current APL is a current APL,

Max APL is a maximum APL,

Target Peak Lum APL is a target peak luminance APL, and

RGB gain weight is a gain weight of the RGB data signals.

11. The method of claim 9, further comprising:

controlling luminance of at least one frame on the basis of the correction gain values,

wherein the luminance control value is used for setting a gamma voltage.

12. The method of claim 9, wherein the correction gain value of the green (G) data signal is calculated in accordance with the following equation:

Current gain of G data signal=(Max APL G gain−

Target Peak Lum APL G gain)*{(Current APL−

Target Peak Lum APL)/(Max APL−

Target Peak Lum APL)}+Target Peak Lum APL G gain,

wherein;

Max APL G gain is an actual gain measurement value of the G data signal corresponding to the maximum APL,

Target Peak Lum APL G gain is an actual gain measurement value of the G data signal corresponding to the target peak luminance APL,

Current APL is a current APL,

Max APL is a maximum APL, and

Target Peak Lum APL is an APL of target peak luminance.

13. The method of claim 9, wherein the correction gain value of the blue (B) data signal is calculated in accordance with the following equation:

Current gain of B data signal=(Max APL B gain−

Target Peak Lum APL B gain)*{(Current APL−

Target Peak Lum APL)/(Max APL−

Target Peak Lum APL)}+Target Peak Lum APL B gain+B gain weight,

wherein;

Max APL B gain is an actual gain measurement value of the B data signal corresponding to the maximum APL,

Target Peak Lum APL B gain is an actual gain measurement value of the B data signal corresponding to the target peak luminance APL,

Current APL is a current APL,

Max APL is a maximum APL,

Target Peak Lum APL is an APL of target peak luminance,

Target Peak Lum APL is an APL of target peak luminance, and

B gain weight is a gain weight of the B data signal.

14. The method of claim 12, wherein the Target Peak Lum APL is a setter input variable limiting the APL of the target peak luminance.

15. The method of claim 13, wherein the Target Peak Lum APL is a setter input variable limiting the APL of the target peak luminance.

16. The method of claim 13, wherein the gain weights of the RGB data signals are prepared on the basis of actual measurement values obtained by measuring the characteristics of the RGB subpixels.

17. An organic light emitting display device, comprising:

a display panel comprising red, green, blue, and white (RGBW) subpixels;

a scan driver and a data driver configured to drive scan lines and data lines of the display panel, respectively;

a timing controller configured to control the scan driver and the data driver;

a data extraction unit configured to;

determine a representative value of every pixel in one frame data supplied from the outside; and

average the representative values over all of the pixels;

an average picture level (APL) calculation unit configured to calculate an APL by performing an arithmetical operation on the averaged representative values extracted from the data extraction unit; and

a peak luminance controller configured to control luminance of each of at least one frame by using the APL calculated by the APL calculation unit and a look-up table.

18. The organic light emitting display device of claim 17, wherein the data extraction unit is further configured to:

determine a representative value for each respective pixel, such that a subpixel value comprising a greatest data value among RGB subpixels in a single pixel is determined as a representative value for the single pixel; and

subsequently average the representative values over all of the pixels.

19. The organic light emitting display device of claim 17, wherein the data extraction unit, the APL calculation unit, and the PLC are included in an image processing unit configured to supply frame data to the timing controller.

20. A method of driving an organic light emitting display device, the method comprising:

determining a representative value for each respective pixel, such that a subpixel value comprising a greatest data value among red, green, and blue (RGB) subpixels in a single pixel is determined as a representative value for the single pixel;

subsequently averaging the representative values over all of the pixels;

calculating an average picture level (APL) by performing an arithmetical operation on the extracted averaged representative values; and

controlling the luminance of each of at least one frame by using the calculated APL and a look-up table.

21. The method of claim 20, wherein, in the controlling of luminance, the luminance is controlled in units of a plurality of frames by using the APL.

22. The method of claim 20, wherein, in the calculating of an APL, the averaged representative values are performed in units of Nth frames such that the identical APL is applied to the plurality of frames.