METHOD OF DIMMING BACKLIGHT ASSEMBLY

• US 20140085351A1
• Filed: 12/02/2013
• Published: 03/27/2014
• Est. Priority Date: 03/22/2010
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Yeo, Dongmin, Yang, Byungchoon, Kwon, Yong-Hoon, JUNG, TAE KWON
• Granted Patent: US 9,099,049 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127

Abstract

A plurality of gray-scale values is extracted from image signals corresponding to a dimming area to calculate a mean value of the gray-scale values, and at least one of a variance, a standard deviation, a kurtosis, a skewness, a central moment, and an image moment is calculated using the mean value. Then, a representative gray-scale value corresponding to the dimming area is determined using the calculated values, and a dimming function for the light sources included in the dimming area is determined based on the representative gray-scale value. Then, the light sources included in the dimming area are driven based on the dimming function.

Claims

1. A method of dimming a backlight assembly of a display panel comprising a plurality of light sources divided into at least one dimming area, the method comprising:

providing image signals to the display panel;

extracting a plurality of gray-scale values from image signals corresponding to the dimming area to calculate a mean value of the gray-scale values;

calculating a kurtosis and a skewness using the mean value to output the kurtosis and the skewness as a first calculated value;

calculating at least one of a variance, a standard deviation, a central moment, and an image moment using the mean value to output at least one of the variance, the standard deviation, the central moment, and the image moment as a second calculated value;

determining a representative gray-scale value corresponding to the dimming area using the first and the second calculated values;

determining a dimming function for the light sources included in the dimming area based on the representative gray-scale value; and

driving the light sources included in the dimming area based on the dimming function.

2. The method of claim 1, further comprising calculating a minimum value or a maximum value of the gray-scale values.

3. The method of claim 2, wherein determining the dimming function comprises:

extracting a target brightness value corresponding to the representative gray-scale value using a target gamma curve;

extracting a light-emitting brightness value of the light sources using the target brightness value; and

determining the dimming function for the light sources included in the dimming area in response to the light-emitting brightness value.

4. The method of claim 2, wherein the representative gray-scale value is determined by a function of a first degree or higher of the first and the second calculated values.

5. The method of claim 4, wherein said function includes a log function of the first and the second calculated values.

6. The method of claim 4, wherein said function includes an exponential function of the first and the second calculated values.

7. The method of claim 2, wherein the image moment comprises a raw image moment of an n-th degree or lower, where n is a number of the gray-scale values.

8. The method of claim 2, wherein the image moment comprises a central image moment of an n-th degree or lower, where n is a number of the gray-scale values.

9. The method of claim 2, wherein the image moment comprises a raw image moment of an n-th degree or lower and a central image moment of the n-th degree or lower, where n is a number of the gray-scale values.

10. The method of claim 9, wherein the representative gray-scale value GRE is represented by the following formula:

γ

₂≧

0,GRE=α

×

m+(1−

α

)×

P,

γ

₂<

0,GRE=α

×

+(1−

α

)×

P−

β

γ

₁,

wherein m denotes the mean value, P denotes the maximum value, γ

₁ denotes the kurtosis, γ

₂ denotes the skewness,

11. The method of claim 9, wherein the representative gray-scale value GRE is represented by the following formula:

12. The method of claim 9, wherein the representative gray-scale value GRE is represented by the following formula:

13. The method of claim 9, wherein the representative gray-scale value GRE is represented by the following formula:

A≦

T₁,GRE=m,

A≧

T₂,GRE=P,

wherein A is greater than T₁ and less than T₂ (T₁<

A<

T₂), the representative gray-scale value satisfies GRE=α

×

m+(1−

α

)×

P when the kurtosis γ

₁ is greater than zero (γ

₁>

0), the representative gray-scale value satisfies a condition of GRE=(1−

β

)×

m+β

×

P when the kurtosis γ

₁ is equal to or smaller than zero (γ

₁≦

0),

wherein A=| x|+| y|+√

{square root over (|μ

₁₁|)}, x denotes an x-axis average raw image moment of the gray-scale values, y denotes a y-axis average raw image moment of the gray-scale values, μ

_ij denotes the central image moment of an i-th degree along the x-axis and of a j-th degree along the y-axis, m denotes the mean value, P denotes the maximum value, γ

₁ denotes the kurtosis, T, and T₂ are predetermined threshold values, α

=Kγ

₁γ

₂, β

=−

Kγ

₁γ

₂, K denotes a predetermined constant, and γ

₂ denotes the skewness.

14. A method of dimming a backlight assembly of a display panel comprising a plurality of light sources divided into at least one dimming area, the method comprising:

providing image signals to the display panel;

extracting a plurality of gray-scale values from image signals corresponding to the dimming area to calculate a median value of the gray-scale values;

calculating a kurtosis and a skewness using the mean value to output the kurtosis and the skewness as a first calculated value;

calculating at least one of a variance, a standard deviation, a central moment, and an image moment using the median value to output at least one of the variance, the standard deviation, the central moment, and the image moment as a second calculated value;

determining a representative gray-scale value corresponding to the dimming area using the first and the second calculated values;

determining a dimming function for the light sources included in the dimming area based on the representative gray-scale value; and

driving the light sources included in the dimming area based on the dimming function.

15. The method of claim 14, further comprising calculating a minimum value or a maximum value of the gray-scale values.

16. The method of claim 15, wherein the representative gray-scale value is determined by a function of a first degree or higher of the first and the second calculated values.

17. The method of claim 16, wherein said function includes a log function of the first and the second calculated values.

18. The method of claim 16, wherein said function includes an exponential function of the first and the second calculated values.

19. A method of dimming a backlight assembly of a display panel comprising a plurality of light sources divided into at least one dimming area, the method comprising:

providing image signals to the display panel;

extracting a plurality of gray-scale values from image signals corresponding to the dimming area to calculate a mode value of the gray-scale values;

calculating a kurtosis and a skewness using the mean value to output the kurtosis and the skewness as a first calculated value;

calculating at least one of a variance, a standard deviation, a central moment, and an image moment using the mode value to output at least one of the variance, the standard deviation, the central moment, and the image moment as a second calculated value;

determining a representative gray-scale value corresponding to the dimming area using the first and the second calculated values;

determining a dimming function for the light sources included in the dimming area based on the representative gray-scale value; and

driving the light sources included in the dimming area based on the dimming function.

20. The method of claim 19, further comprising calculating a minimum value or a maximum value of the gray-scale values.

21. The method of claim 20, wherein the representative gray-scale value is determined by a function of a first degree or higher of the first and the second calculated values.

22. The method of claim 21, wherein said function includes a log function of the first and the second calculated values.

23. The method of claim 21, wherein said function includes an exponential function of the first and the second calculated values.