Method of local dimming of display light source and apparatus performing same
In a machine-implemented method of local dimming a light source of a light source block for driving the light source block to provide a plurality of image regions with light, duty ratios of a first light source and a second light source adjacent to the first light source are initially determined by using a first target luminance value of a first image region closest to the first light source and a second target luminance value of a second image region closest to the second light source. The initially determined duty ratios are compensated by using a target luminance value of a remaining image region excluding the first and second image regions among the image regions receiving the light generated from the first and second first light sources. The first and second first light sources are driven by using the compensated duty ratios.
1. A machine-implemented method of controlling local dimming of a plurality of light sources each corresponding to a respective light source block, where each light source block provides backlighting for an associated plurality of image regions, the method comprising:
(a) initially determining first respective duty ratios for respectively driving a first of the light sources and a second of the light sources, where the first and second of the light sources neighbor one another, where said initial determining uses a first target luminance value of a first image region that is closest to the first light source and a second target luminance value of a second image region that is closest to the second light source, and where the initial determining thereby establishes the first respective duty ratios as current respective duty ratios;
(b) second determining if the combination of the established current respective duty ratios expectedly provide sufficient minimal backlighting for a third image region to support a corresponding third target luminance value of the third image region, and if not adjusting the current respective duty ratios to thereby increase the expected backlighting for a third image region, where the adjusting is based on a difference between the third target luminance value and the expected contribution from the first and second light sources when driven in accordance with the pre-adjustment current respective duty ratios; and
(c) driving the first and second first light sources in accordance with the first respective duty ratios if the second determining determines that the first respective duty ratios are sufficient,
wherein said adjusting of the current respective duty ratios comprises:
a machine-implemented calculating of M-th compensation values corresponding to an M-th image region by calculating an M-th expected luminance value by using the current respective duty ratios;
calculating a luminance difference between the M-th expected luminance value and an M-th target luminance value; and
if the M-th expected luminance value is smaller than the M-th target luminance value, calculating the M-th compensation values by using the luminance difference.
2. The machine-implemented method of claim 1 , further comprising:
determining respective target luminance values for corresponding ones of the image regions, where each of the target luminance values is determined by using a maximum grayscale data value extracted from among grayscale data values to be displayed by the respective image region.
3. The machine-implemented method of claim 1 , wherein the initially determined first duty ratios repeatedly have compensations added to them N times when the number of remaining image regions beyond the first and second image regions is M, where M and N are whole numbers greater than zero, and
the first and second first light sources are driven by using the N times compensated duty ratio values, wherein N is no more than M+1.
4. The machine-implemented method of claim 1 , wherein said adjusting of the current respective duty ratios further comprises:
adding the M-th compensation values to the current respective duty ratios to thereby define potentially more current respective duty ratios.
5. The method of claim 4 , wherein the M-th compensation values are not added to the current respective duty ratios to thereby define the potentially more current respective duty ratios if such additions will cause the potentially more current respective duty ratios to be smaller than the current respective duty ratios.
6. The method of claim 1 , wherein the M-th compensation values are not calculated when the M-th expected luminance value is equal to or larger than the M-th target luminance value.
7. The method of claim 1 , wherein the M-th compensating values (ΔPa, ΔPb) are calculated by automatically solving the following Equations:
(
Xa
×
Δ
P
a
)
+
(
Xb
×
Δ
Pb
)
=
Δ
Y
(
Ka
×
Δ
P
a
)
=
(
Kb
×
Δ
Pb
)
Ka
=
ⅆ
a
ⅆ
t
Kb
=
ⅆ
b
ⅆ
t
wherein Xa is the ratio of a luminance that is measured in the center of the M-th image region to a luminance that is measured in the center of the first light source La, Xb is the ratio of a luminance that is measured in the center of the M-th image region to a luminance that is measured in the center of the second light source Lb, Ka is the ratio of a total distance, dt between the first light source La and the second light source Lb the included distance da between the first light source La and the center of the M-th image region, Kb is the ratio of the total distance, dt and the included distance db between the second light source Lb and the center of the M-th image region.
8. A light source apparatus comprising:
a light source module comprising a plurality of light source blocks, each of the light source blocks including a light source providing light to a plurality of image regions; and
a local dimming driving part that drives first and second light sources of first and second light source blocks by using duty ratios determined based on target luminance values of the image regions receiving light from the first light source block and the second light source block adjacent to the first light source block,
wherein the local dimming driving part comprises:
a duty determining part firstly determining duty ratios of a first light source and a second light source adjacent to the first light source by using a first target luminance value of a first image region facing the first light source and a second target luminance value of a second image region facing the second light source;
a duty compensating part compensating the firstly determined duty ratios by using a target luminance value of a remaining image region excluding the first and second image regions among the image regions receiving light of the first and second first light sources; and
a light source driving part that drives the first and second first light sources by using the compensated duty ratios, and
wherein the duty compensating part calculates M-th compensation values based on a luminance difference between an M-th expected luminance value and an M-th target luminance value of an M-th image region of the remaining image region, and applying the M-th compensation value to pre-determined duty ratios to redetermine the duty ratios.
9. The light source apparatus of claim 8 , wherein the light source blocks are aligned in one direction.
10. The light source apparatus of claim 8 , further comprising
an image analyzing part determining the target luminance values of the image regions,
wherein each of the target luminance values is determined by using a maximum grayscale data is extracted among grayscale data of the image regions.
11. The light source apparatus of claim 8 , wherein the duty compensating part repeatedly compensates the firstly (initially) determined duty ratios in N times when the number of the remaining image regions is M, wherein N is no more than M+1, and N and M are natural number.
12. The light source apparatus of claim 8 , wherein the duty compensating part does not apply the M-th compensation value to the pre-determined duty ratios when the duty ratios to which the M-th compensation value has been applied is smaller than the pre-determined duty ratios.
13. The light source apparatus of claim 8 , wherein the duty compensating part further comprising:
a first calculating part that automatically calculates the M-th expected luminance value by using the pre-determined duty ratios;
a second calculating part that automatically calculates a luminance different between the M-th expected luminance value and the M-th target luminance value; and
a third calculating part that automatically calculates the M-th compensation values by using the luminance difference.
14. The light source apparatus of claim 13 , wherein the third calculating part does not calculate the M-th compensation values when the M-th expected luminance value is larger than the M-th target luminance value.
15. The light source apparatus of claim 13 , wherein the third calculating part automatically calculates the M-th compensating values (ΔPa, ΔPb) by the following Equations:
(
Xa
×
Δ
P
a
)
+
(
Xb
×
Δ
Pb
)
=
Δ
Y
(
Ka
×
Δ
P
a
)
=
(
Kb
×
Δ
Pb
)
Ka
=
ⅆ
a
ⅆ
t
Kb
=
ⅆ
b
ⅆ
t
wherein Xa is the ratio of a luminance that is measured in the center of the M-th image region to a luminance that is measured in the center of the first light source La, Xb is the ratio of a luminance that is measured in the center of the M-th image region to a luminance that is measured in the center of the second light source Lb, Ka is the ratio of a distance dt between the first light source La and the center of the M-th image region to a distance da between the first light source La and the second light source Lb, Kb is the ratio of a distance dt between the second light source Lb and the center of the M-th image region to a distance db between the first light source La and the second light source Lb.
16. A display apparatus comprising:
a light source module comprising a plurality of light source blocks, each of the light source blocks including a light source generating light;
a display panel receiving the light generated from the light source module, and comprising of a plurality of image regions, the number of the image regions being greater than the number of the light source blocks; and
a local dimming driving part that drives first and second light sources of first and second light source blocks by using duty ratios determined based on target luminance values of the image regions receiving light from the first light source block and the second light source block adjacent to the first light source block,
wherein the local dimming driving part comprises:
a duty determining part firstly determining duty ratios of a first light source and a second light source adjacent to the first light source by using a first target luminance value of a first image region adjacent to the first light source and a second target luminance value of a second image region adjacent to the second light source;
a duty compensating part compensating the firstly determined duty ratios by using a target luminance value of a remaining image region excluding the first and second image regions among the image regions receiving light of the first and second first light sources; and
a light source driving part that drives the first and second first light sources by using the compensated duty ratios, and
wherein the duty compensating part calculates M-th compensation values based on a luminance difference between an M-th expected luminance value and an M-th target luminance value of an M-th image region of the remaining image region, and applying the M-th compensation value to pre-determined duty ratios to redetermine the duty ratios.
17. The display apparatus of claim 16 , wherein the number of the image regions is a multiple of the number of the light source blocks.
18. The display apparatus of claim 17 , wherein the number of the image regions is substantially equal to a difference between the multiple of the number of the light source blocks and the number of image regions commonly corresponding to adjacent light source blocks.
19. The display apparatus of claim 17 , wherein the number of the image regions is smaller than the multiple of the number of the light source blocks by one.
20. The display apparatus of claim 16 , wherein the number of the image regions is a multiple of the number of a gate driving circuit.
21. The display apparatus of claim 16 , wherein the duty compensating part further comprising:
a first calculating part that automatically calculates the M-th expected luminance value by using the pre-determined duty ratios;
a second calculating part that automatically calculates a luminance different between the M-th expected luminance value and the M-th target luminance value; and
a third calculating part that automatically calculates the M-th compensation values by using the luminance difference.