LED driving circuit and method

1. A LED driving circuit used to generate a driving current to drive the LED during a grayscale period according to a grayscale signal, comprising:

a high bit driving circuit coupled to a high bit signal of the grayscale signal determining a first current continuously driven during the grayscale period according to a value of the high bit signal of the grayscale signal, wherein the first current is invariant during the grayscale period;

a low bit driving circuit coupled to a low bit signal of the grayscale signal determining a second current driven in at least two time intervals during the grayscale period according to a value of the low bit signal of the grayscale signal; and

a driving output terminal coupled to the high bit driving circuit and the low bit driving circuit outputting the driving current added by the first current and the second current;

wherein a ratio of the first current to a constant current is m/(2 k ), m is the value of the high bit signal, and k is a bit number of the high bit signal.

2. The LED driving circuit according to claim 1 , wherein the grayscale signal has n−bit, n is a positive integer greater than 1, the grayscale period is divided into 2 n or (2 n −1) grayscale steps, k is a positive integer smaller than n, wherein the value of the low bit signal is p, the value of the grayscale signal corresponds to a product of the constant current and a time during the grayscale period, the product is (m×2 (n−k) +p)×T 1 ×I, I is the constant current, and T 1 is the grayscale step.

3. The LED driving circuit according to claim 1 , wherein the grayscale signal has n-bit, n is a positive integer greater than 1, the grayscale period is divided into 2 n or (2 n− 1) grayscale steps, and the product of the second current and the time is p×T 1 ×the constant current during the grayscale period, wherein p is the value of the low bit signal, and T 1 is the grayscale step.

4. The LED driving circuit according to claim 1 , wherein a ratio of the second current to the constant current is 1/(2 k ).

5. The LED driving circuit according to claim 4 , wherein the total turn-on time of the at least two time intervals of the second current is the value of the low bit signal ×2 k ×the grayscale step.

6. The LED driving circuit according to claim 1 , wherein the LED driving circuit outputs a black insertion signal between the at least two time intervals.

7. The LED driving circuit according to claim 1 , wherein an amount of the at least two time intervals is 2 k .

8. The LED driving circuit according to claim 1 , further comprising: a control circuit configured to transmit the high bit signal to the high bit driving circuit, and to transmit the low bit signal to the low bit driving circuit.

9. A method of driving a LED used to generate a driving current to drive the LED during a grayscale period according to a grayscale signal, comprising:

defining a grayscale signal to be a high bit signal and a low bit signal;

determining a first current continuously driven during a grayscale period according to a value of the high bit signal; wherein the first current is invariant during the grayscale period;

determining a second current driven in at least two time intervals during the grayscale period according to a value of the low bit signal; and

outputting the driving current added by the first current and the second current

wherein a ratio of the first current to a constant current is m/(2 k ), m is the value of the high bit signal, and k is a bit number of the high bit signal.

10. The method according to claim 9 , wherein the grayscale signal has n-bit, n is a positive integer greater than 1, the grayscale period is divided into 2 n or (2 n −1) grayscale steps, k is a positive integer smaller than n, wherein the value of the low bit signal is p, the value of the grayscale signal corresponds to a product of the constant current and a time during the grayscale period, the product is (m×2 (n−k) +p)×T 1 ×I, I is the constant current, and T 1 is the grayscale step.

11. The method according to claim 9 , wherein the grayscale signal has n-bit, n is a positive integer greater than 1, the grayscale period is divided into 2 n or (2 n −1) grayscale steps, and the product of the second current and the time is p×T 1 ×the constant current during the grayscale period, wherein p is the value of the low bit signal, and T 1 is the grayscale step.

12. The method according to claim 9 , wherein a ratio of the second current to the constant current is 1/(2 k ).

13. The method according to claim 12 , wherein the total turn-on time of the at least two time intervals of the second current is the value of the low bit signal ×2 k ×the grayscale step.

14. The method according to claim 9 , further comprising: outputting a black insertion signal between the at least two time intervals.

15. The method according to claim 9 , wherein an amount of the at least two time intervals is 2 k .

16. A LED driving circuit used to generate a driving current to drive the LED during a grayscale period according to a grayscale signal, wherein the LED driving circuit adjusts an initial current value of the driving current according to a high bit signal of the grayscale signal and increases the driving current in at least two time intervals according to a low bit signal of the grayscale signal to enable the driving current to be greater than the initial current value in the at least two time intervals; wherein the initial current value is ≥0;

wherein the initial current value is a first current determined by the high bit signal, the low bit signal determines a second current, and the driving current in the at least two time intervals is a summation of the first current and the second current; and

wherein a ratio of the first current to a constant current is m/(2 k ), m is a value of the high bit signal, and k is a bit number of the high bit signal.

17. The LED driving circuit according to claim 16 , wherein the LED driving circuit outputs a black insertion signal between the at least two time intervals.