Display device and method of driving the same

1. A display device comprising:

a display panel which displays an image based on input image data;

a driving controller which generates a voltage control signal for adjusting a first power voltage applied to the display panel in an (N+M)-th frame based on a maximum grayscale value of the input image data of an N-th frame, wherein N is a positive integer, and M is a positive integer; and

a power voltage generator which senses a power current applied to the display panel in the (N+M)-th frame, generates a second power voltage based on the voltage control signal, and controls a voltage level of the first power voltage based on the second power voltage and a current level of the power current.

2. The display device of claim 1 , wherein the driving controller determines a scale factor for adjusting a grayscale value of the input image data of the (N+M)-th frame based on a load of the input image data of the N-th frame and a grayscale adjustment reference value.

3. The display device of claim 2 , wherein the power voltage generator includes:

a power voltage generating block which generates the first power voltage and the second power voltage based on an input voltage and the voltage control signal, and controls the voltage level of the first power voltage based on the second power voltage and an analog voltage;

a power voltage supply which applies the input voltage to the power voltage generating block;

a reference current calculator which calculates a reference current based on a voltage level of the second power voltage and a reference power consumption lookup table;

a current sensing block which senses the power current and generates a voltage drop signal based on the current level of the power current and the reference current;

a voltage code generating block which outputs a power voltage code based on the voltage drop signal and a voltage code lookup table; and

a power voltage digital-to-analog converter block which generates the analog voltage based on the power voltage code.

4. The display device of claim 3 , wherein the reference current calculator receives a reference power consumption from the reference power consumption lookup table, and calculates the reference current by dividing the reference power consumption by the voltage level of the second power voltage.

5. The display device of claim 4 ,

wherein the reference power consumption includes a first reference power consumption, a second reference power consumption greater than the first reference power consumption, and a third reference power consumption greater than the second reference power consumption,

wherein the reference current includes a first reference current, a second reference current, and a third reference current,

wherein the first reference current is calculated by dividing the first reference power consumption by the voltage level of the second power voltage,

wherein the second reference current is calculated by dividing the second reference power consumption by the voltage level of the second power voltage, and

wherein the third reference current is calculated by dividing the third reference power consumption by the voltage level of the second power voltage.

6. The display device of claim 5 , wherein the third reference power consumption is less than or equal to a maximum power consumption of the power voltage supply.

7. The display device of claim 5 , wherein the current sensing block outputs a first voltage drop signal with an activation level when the power current is greater than the first reference current, outputs a second voltage drop signal with an activation level when the power current is greater than the second reference current, and outputs a third voltage drop signal with an activation level when the power current is greater than the third reference current.

8. The display device of claim 3 , wherein the voltage code generating block is which receives the voltage drop signal from the current sensing block, receives a vertical start signal from the driving controller, and calculates an activation start time of the voltage drop signal based on the vertical start signal.

9. The display device of claim 8 , wherein the voltage code generating block outputs the power voltage code corresponding to a type of the voltage drop signal and the activation start time of the voltage drop signal among a plurality of power voltage codes stored in the voltage code lookup table.

10. The display device of claim 9 , wherein the power voltage generating block receives the analog voltage from the power voltage digital-to-analog converter block and controls the voltage level of the first power voltage based on the analog voltage.

11. The display device of claim 2 , wherein the driving controller further includes:

a load sum calculator which receives the input image data of the N-th frame to calculate a sum of all grayscale values of the input image data of the N-th frame; and

a load calculator which receives the sum of all grayscale values of the input image data of the N-th frame to calculate the load of the input image data of the N-th frame.

12. The display device of claim 11 , wherein the driving controller further includes:

a maximum grayscale value calculator which receives the input image data of the N-th frame and calculates the maximum grayscale value of the input image data of the N-th frame.

13. The display device of claim 12 , wherein the driving controller further includes:

a voltage control signal generating block which generates the voltage control signal for adjusting the first power voltage applied to the display panel in the (N+M)-th frame based on the load of the input image data of the N-th frame, the maximum grayscale value of the input image data of the N-th frame, and a voltage control lookup table; and

a grayscale adjuster which determines the scale factor for adjusting the grayscale value of the input image data of the (N+M)-th frame based on the load of the input image data of the N-th frame and the grayscale adjustment reference value.

14. A method of driving a display device, the method comprising:

generating a voltage control signal for adjusting a first power voltage applied to a display panel of the display device in an (N+M)-th frame based on a maximum grayscale value of input image data of an N-th frame, wherein N is a positive integer, and M is a positive integer;

sensing a power current applied to the display panel in the (N+M)-th frame;

generating a second power voltage based on the voltage control signal; and

controlling a voltage level of the first power voltage based on the second power voltage and a current level of the power current.

15. The method of claim 14 , further comprising:

determining a scale factor for adjusting a grayscale value of the input image data of the (N+M)-th frame based on a load of the input image data of the N-th frame and a grayscale adjustment reference value.

16. The method of claim 15 , the controlling the voltage level of the first power voltage includes:

calculating a reference current based on a voltage level of the second power voltage and a reference power consumption lookup table;

generating a voltage drop signal based on the current level of the power current and the reference current;

outputting a power voltage code based on the voltage drop signal and a voltage code lookup table;

generating an analog voltage based on the power voltage code; and

controlling the voltage level of the first power voltage based on the second power voltage and the analog voltage.

17. The method of claim 16 , wherein the reference current is calculated by dividing a reference power consumption received from the reference power consumption lookup table by the voltage level of the second power voltage.

18. The method of claim 17 ,

wherein the reference power consumption includes a first reference power consumption, a second reference power consumption greater than the first reference power consumption, and a third reference power consumption greater than the second reference power consumption,

wherein the reference current includes a first reference current, a second reference current, and a third reference current,

wherein the first reference current is calculated by dividing the first reference power consumption by the voltage level of the second power voltage,

wherein the second reference current is calculated by dividing the second reference power consumption by the voltage level of the second power voltage, and

wherein the third reference current is calculated by dividing the third reference power consumption by the voltage level of the second power voltage.

19. The method of claim 18 , the outputting the power voltage code includes:

outputting a first voltage drop signal with an activation level when the power current is greater than the first reference current;

outputting a second voltage drop signal with an activation level when the power current is greater than the second reference current; and

outputting a third voltage drop signal with an activation level when the power current is greater than the third reference current.

20. The method of claim 16 , the outputting the power voltage code includes:

calculating an activation start time of the voltage drop signal based on a vertical start signal; and

outputting the power voltage code corresponding to a type of the voltage drop signal and the activation start time of the voltage drop signal among a plurality of power voltage codes stored in the voltage code lookup table.