Method of dimming backlight assembly

• US 9,099,049 B2
• Filed: 12/02/2013
• Issued: 08/04/2015
• Est. Priority Date: 03/22/2010
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Jung, Tae Kwon, Yeo, Dongmin, Yang, Byungchoon, Kwon, Yong-Hoon
• Primary Examiner(s): Mengistu, Amare
• Assistant Examiner(s): Figueroa-Gibson, Gloryvid
• Application Number:
  US14/094,153
• Publication Number:
  US 20140085351A1
• Time in Patent Office: 610 Days
• Field of Search: 345/82, 345/87, 345/90, 345/102, 345/690
• US Class Current: 1/1
• 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 location parameter value of the gray-scale values;

calculating a kurtosis and a skewness using the location parameter 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 location parameter value to output at least one of the variance, the standard deviation, the central moment, and the image moment as a second calculated value;

calculating a maximum value of the gray-scale values;

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,

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

×

m+(1−

α

)×

P−

β

γ

₁,

wherein

m denotes the location parameter value, P denotes the maximum value,

γ

₁ denotes the kurtosis, γ

₂ denotes the skewness,

2. The method of claim 1, 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.

3. The method of claim 1, 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.

4. The method of claim 1, wherein the location parameter is one of a mean, a median, or a mode.

5. 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 location parameter value of the gray-scale values;

calculating a kurtosis and a skewness using the location parameter 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 location parameter 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,

wherein the representative gray-scale value GRE is represented by the following formula;

6. The method of claim 5, further comprising calculating a minimum value or a maximum value of the gray-scale values.

7. The method of claim 5, 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.

8. The method of claim 5, 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.

9. The method of claim 5, wherein the location parameter is one of a mean, a median, or a mode.

10. 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 location parameter value of the gray-scale values;

calculating a kurtosis and a skewness using the location parameter 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 location parameter value to output at least one of the variance, the standard deviation, the central moment, and the image moment as a second calculated value;

calculating a maximum value of the gray-scale values;

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,

wherein the representative gray-scale value GRE is represented by the following formula;

11. The method of claim 10, 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.

12. The method of claim 10, 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.

13. The method of claim 10, wherein the location parameter is one of a mean, a median, or a mode.

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 location parameter value of the gray-scale values;

calculating a kurtosis and a skewness using the location parameter 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 location parameter value to output at least one of the variance, the standard deviation, the central moment, and the image moment as a second calculated value;

calculating a maximum value of the gray-scale values;

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,

wherein the representative gray-scale value GRE is represented by the following formula;

A≦

T₁,GRE=m,

A≧

T₂,GRE=P,

wherein

when 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 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

_ij|)},

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 a 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 location parameter value,

P denotes the maximum value,

γ

₁ denotes the kurtosis, γ

₂ denotes the skewness,

T₁ and T₂ are predetermined threshold values,

α

=Kγ

₁γ

₂, β

=−

Kγ

₁γ

₂, and

K denotes a predetermined constant.

15. The method of claim 14, 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.

16. The method of claim 14, 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.

17. The method of claim 14, wherein the location parameter is one of a mean, a median, or a mode.