Display device and local method of controlling local dimming thereof

1. A display device comprising:

a display panel;

a backlight unit including a plurality of blocks for providing light to the display panel, each of the plurality of blocks comprising a plurality of light emitting diodes (LEDs); and

a controller configured to:

obtain backlight control information; and

activate a duty ratio control function for controlling a duty ratio and current flowing in a block during a cycle of one frame, when a low current condition is satisfied based on the obtained backlight control information,

wherein the duty ratio control function is a function for controlling the duty ratio and the current such that a product (a*b) of an increase multiple a of the current flowing in the block and the duty ratio b becomes 1,

wherein the controller is further configured to control the duty ratio and the current such that the duty ratio b becomes ((1/n)×100)% when the increase multiple a is n times, and

wherein the controller is further configured to control the block such that the current flowing in the block is 0 during a half cycle of one frame and the current flowing in the block is n times of a current value of a previous frame during the other half cycle.

2. The display device of claim 1 , wherein the controller is further configured to control the current flowing in the block such that the current decreases to 0 stepwise during a first half-cycle start section of the one frame and control the current flowing in the block such that the current is doubled stepwise during the other half-cycle start section of the one frame.

3. The display device of claim 1 ,

wherein the backlight control information comprises a voltage value applied to the block, and

wherein the controller is further configured to determine a value of the current flowing in the block based on the voltage value, and determine that the low current condition is satisfied, when the determined current value is less than a predetermined value.

4. The display device of claim 1 ,

wherein the backlight control information comprises a Pulse Width Modulation (PWM) dimming duty ratio value, and

wherein the controller is further configured to determine that the low current condition is satisfied, when the PWM dimming duty ratio value is less than a predetermined value.

5. A local dimming control method of a display device comprising a display panel and a backlight unit including a plurality of blocks for providing light to the display panel, the local dimming control method comprising:

obtaining backlight control information;

determining whether a low current condition is satisfied based on the obtained backlight control information; and

activating a duty ratio control function for controlling a duty ratio and current flowing in a block during a cycle of one frame when the low current condition is satisfied,

wherein the duty ratio control function is a function for controlling the duty ratio and the current such that a product (a*b) of an increase multiple a of the current flowing in the block and the duty ratio b becomes 1, and

wherein the local dimming control method further comprises:

controlling the duty ratio and the current such that the duty ratio b becomes ((1/n)×100)% when the increase multiple a is n times; and

controlling the block such that the current flowing in the block is 0 during a half cycle of one frame and the current flowing in the block is n times of a current value of a previous frame during the other half cycle.

6. The local dimming control method of claim 5 , wherein the activating the duty ratio control function comprises:

controlling the current flowing in the block such that the current decreases to 0 stepwise during a first half-cycle start section of the one frame, and

controlling the current flowing in the block such that the current is doubled stepwise during the other half-cycle start section of the one frame.

7. The local dimming control method of claim 5 ,

wherein the backlight control information comprises a voltage value applied to the block, and

wherein the local dimming control method further comprises determining a value of the current flowing in the block based on the voltage value and determining that the low current condition is satisfied when the determined current value is less than a predetermined value.

8. The local dimming control method of claim 5 ,

wherein the backlight control information comprises a Pulse Width Modulation (PWM) dimming duty ratio value, and

wherein the local dimming control method further comprises determining that the low current condition is satisfied, when the PWM dimming duty ratio value is less than a predetermined value.