BACKLIGHT SPLIT CONTROL APPARATUS AND BACKLIGHT SPLIT CONTROL METHOD USING THE SAME

• US 20100283802A1
• Filed: 08/26/2009
• Published: 11/11/2010
• Est. Priority Date: 05/08/2009
• Status: Active Grant

• Current Assignee: Korea Electronics Technology Institute (Government of South Korea)
• Original Assignee: Korea Electronics Technology Institute (Government of South Korea)
• Inventors: Lee, Hyungsu, Jung, Hyedong, Jeon, Kiman
• Granted Patent: US 8,665,204 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 5/10 Intensity circuits

Abstract

A backlight split control apparatus and a backlight split control method using the same are provided. The backlight split control apparatus, which is a split control apparatus of the backlight divided into a plurality of sections, includes an image signal processor for calculating a section luminance control value which is a representative luminance value of the section, from an image signal; a control signal generator for calculating a backlight control value which is a control signal of the backlight, by correcting a section luminance calculation value using a difference between the section luminance control value and the section luminance calculation value acquired from a section luminance distribution value of a light source of the backlight; and an image signal regulator for adjusting the image signal using the backlight control value.

Claims

1. A split control apparatus of a backlight which is divided into a plurality of sections, comprising:

an image signal processor for calculating a section luminance control value which is a representative luminance value of the section, from an image signal;

a control signal generator for calculating a backlight control value which is a control signal of the backlight, by correcting a section luminance calculation value using a difference between the section luminance control value and the section luminance calculation value acquired from a section luminance distribution value of a light source of the backlight; and

an image signal regulator for adjusting the image signal using the backlight control value.

2. The split control apparatus of claim 1, wherein the representative luminance value is a maximum luminance value or an average luminance value of the section.

3. The split control apparatus of claim 2, wherein the section luminance control value is a section maximum luminance control value when the representative luminance value is the maximum luminance value of the section, and

the section maximum luminance control value is expressed by the following equation:

B_m^rep=maxi|i ∈

m-th section

where B_m^rep denotes a section maximum luminance control value of an m-th section, and i denotes a luminance value in the section.

4. The split control apparatus of claim 3, wherein the section luminance calculation value is expressed by the following equation:

5. The split control apparatus of claim 3, wherein the corrected backlight control value is expressed by the following equation:

b_m^[n]=b_m<sup>[n−

1]</sup>+(B_m^rep−

B<sup>[n−

1]</sup>(x_m,y_m))ρ

_m

where b_m^[n] denotes a luminance control signal value corrected for n times of an m-th section, b_m<sup>[n−

1]</sup> denotes the luminance control signal value corrected for (n−

1) times of the m-th section, B_m^rep denotes a section maximum luminance control signal of the m-th section, B<sup>[n−

1]</sup>(x_m,y_m) denotes a luminance value at coordinates (x_m,y_m) in the m-th section with the (n−

1)-time correction, and ρ

_m denotes a weight according to a position of the m-th section.

6. The split control apparatus of claim 5, wherein ρ

_m is a ratio of the number of actually affecting sections to the total number of the sections of the backlight.

7. The split control apparatus of claim 3, further comprising:

a control signal verifier for verifying the backlight control value.

8. The split control apparatus of claim 7, wherein the control signal verifier verifies whether the backlight control value meets the following equation:

|B(x,y)−

I(x,y)|≦

ε

(x,y)

where B(x,y), I(x,y) and ε

(x,y) denote the luminance value at the coordinates (x,y) in the backlight, a required luminance value of an input image signal, and an allowable error value respectively.

9. The split control apparatus of claim 8, wherein the control signal verifier recalculates the backlight control signal to meet the following equation when |B(x,y)−

I(x,y)| is greater than ε

(x,y);

B_m^rep=max(B(x,y)∥

B(x,y)−

I(x,y)|>

ε

(x,y),B(x,)≦

I(x,y))

where B_m^rep denotes an m-th section maximum luminance control value.

10. A split control method of a backlight which is divided into a plurality of sections, comprising:

calculating a section luminance control value which is a representative luminance value of the section, from an image signal;

calculating a backlight control value which is a control signal of the backlight, by correcting a section luminance calculation value using a difference between the section luminance control value and the section luminance calculation value acquired from a section luminance distribution value of a light source of the backlight; and

adjusting the image signal using the backlight control value.

11. The split control method of claim 10, wherein the representative luminance value is a maximum luminance value or an average luminance value of the section.

12. The split control method of claim 10, further comprising:

verifying the generated backlight control value.

13. The split control method of claim 12, wherein the verifying of the backlight control value further comprises:

determining whether a luminance value at certain coordinates (x,y) in the backlight and a required luminance value of the input image signal exceed an allowable error value.

14. The split control method of claim 11, wherein the section luminance control value is a section maximum luminance control value when the representative luminance value is the maximum luminance value of the section, and

when the luminance value at the certain coordinates (x, y) in the backlight and the required luminance value of the input image signal exceed the allowable error value, the backlight control value is recalculated using B_m^rep which meets the following equation:

B_m^rep=max(B(x,y)∥

B(x,y)−

I(x,y)|>

ε

(x,y),B(x,)≦

I(x,y))

where B(x,y), I(x,y) and ε

(x,y) denote the luminance value at the coordinates (x,y) in the backlight, the required luminance value of the input image signal, and the allowable error value respectively, and B_m^rep denotes an m-th section maximum luminance control value.