Liquid crystal display and dimming controlling method thereof

1. A liquid crystal display device comprising:

a liquid crystal display panel;

a drive circuit supplying a data pulse and a gate pulse to the liquid crystal display panel;

a backlight unit divided into a plurality of block including light sources, and irradiating lights of which luminescence is controlled by the blocks, respectively;

a controller analyzing an input video data by the block unit, generating a block dimming value based on a result of the analyzing, repeating a low pass filtering to the block dimming value to generate a local dimming value, applying a predeterminded global dimming value to an average of the local dimming value to generate a dimming signal; and

a backlight driver generating a PWM signal for controlling a luminescence of the light sources by the blocks respectively according to the dimming signal to drive the light sources by the blocks respectively.

2. The device according to the claim 1 , wherein the controller comprises:

a block video analyzer analyzing the digital video data by the blocks respectively to generate a block representative value;

a block dimming decisioner outputting the block dimming value using a look-up table having the block dimming value corresponding to the block representative value;

a low pass filter performing a first low pass filtering to the block dimming value from the block dimming decisioner along to a first direction, performing a second low pass filtering along to a second direction opposite to the first direction, selecting a larger value between results of the first low pass filtering and the second low pass filtering, and repeating the first low pass filtering and the second low pass filtering along to up and down direction and to left and right direction respectively;

a moving average filter averaging the local dimming values outputted from the low pass filter; and

a multiplexer multiplying the averaged local dimming value to the global dimming value.

3. The device according to the claim 2 , wherein the low pass filter includes an infinite-impulse-response filter.

4. The device according to the claim 2 , wherein the low pass filter includes a finite impulse response filter.

5. The device according to the claim 2 , wherein the moving average filter generates the averaged local dimming value by adding previous local dimming values which is corresponding to a plurality of frame period and stored in the local dimming value.

6. The device according to the claim 2 , wherein the moving average filter generates the averaged local dimming value by multiplying a predeterminded weight value to a result of the adding previous local dimming values which is corresponding to a plurality of frame period and stored in the local dimming value.

7. The device according to the claim 6 , wherein the weight value is higher as the frame is closer to a current frame.

8. The device according to the claim 2 , wherein the controller further includes a timing controller controlling an operating timing of the drive circuit.

9. A dimming control method of a liquid crystal display device including a liquid crystal display panel; a drive circuit supplying a data pulse and a gate pulse to the liquid crystal display panel; a backlight unit divided into a plurality of block including light sources, and irradiating lights of which luminescence is controlled by the blocks, respectively; comprising:

generating a block dimming value according to a result of analyzing an input video data by the block respectively;

generating a local dimming value by repeating a low pass filtering to the block dimming value;

generating a dimming signal by applying a predeterminded global dimming value to an average of the local dimming value; and

driving the light sources by generating a PWM signal for controlling a luminescence of the light sources by each blocks of the backlight unit respectively.

10. The method according to the claim 9 , further comprising:

generating a block representative value by analyzing the digital video data in each blocks respectively; and

wherein the generating the block dimming outputs the block dimming value using a look-up table having the block dimming value corresponding to the block representative value.

11. The method according to the claim 10 , wherein generating the local dimming value comprising:

performing a first low pass filtering to the block dimming value along to a first direction;

performing a second low pass filtering along to a second direction opposite to the first direction;

selecting a larger value between results of the first low pass filtering and the second low pass filtering; and

repeating the first low pass filtering and the second low pass filtering along to up and down direction and to left and right direction respectively.

12. The method according to the claim 11 , wherein generating the dimming signal includes multiplying the averaged local dimming value to the global dimming value.

13. The method according to the claim 11 , wherein the low pass filtering includes an infinite-impulse-response filter.

14. The method according to the claim 11 , wherein the low pass filtering includes a finite impulse response filter.

15. The method according to the claim 12 , wherein the generating the dimming signal includes generating the averaged local dimming value by adding previous local dimming values which is corresponding to a plurality of frame period and stored in the local dimming value.

16. The method according to the claim 12 , wherein the generating the dimming signal includes the averaged local dimming value by multiplying a predeterminded weight value to a result of the adding previous local dimming values which is corresponding to a plurality of frame period and stored in the local dimming value.

17. The method according to the claim 16 , wherein the weight value is higher as the frame is closer to a current frame.