Organic light-emitting diode display device and driving method thereof

1. An organic light-emitting diode display device, comprising:

a data line;

first and second gate lines crossing the data line;

an emission line crossing the data line;

an organic light-emitting diode device having an anode electrode and a cathode electrode;

a high-level potential driving voltage source for supplying a high-level potential driving voltage to the anode electrode;

a first switch element for connecting a cathode electrode of the organic light-emitting diode device to a first node;

a second switch element for connecting the data line to a second node;

a third switch element for connecting the second node to a ground voltage source;

a driving element for adjusting a current flowing between the cathode electrode of the organic light-emitting diode device and the second node in accordance with a voltage of the first node;

a first capacitor connected between the second gate line and the first node; and

a second capacitor connected between the first node and the second node,

wherein the driving element includes a gate electrode connected to the first node, a source electrode connected to the second node, and a drain electrode connected to the cathode electrode of the organic light-emitting diode device.

2. The organic light-emitting diode display device as recited in claim 1 , wherein the first switch element includes a gate electrode connected to the first gate line, a source electrode connected to the first node, and a drain electrode connected to the cathode electrode of the organic light-emitting diode device.

3. The organic light-emitting diode display device as recited in claim 1 , wherein the second switch element includes a gate electrode connected to the second gate line, a source electrode connected to the data line, and a drain electrode connected to the second node.

4. The organic light-emitting diode display device as recited in claim 1 , wherein the third switch element includes a gate electrode connected to the emission line, a source electrode connected to the ground voltage source, and a drain electrode connected to the second node.

5. A method of driving an organic light-emitting diode display device having a data line, first and second gate lines crossing the data line, an emission line crossing the data line, an organic light-emitting diode device having an anode electrode and a cathode electrode, a first switch element, a second switch element, a third switch element, a driving element, a first capacitor and a second capacitor, comprising:

supplying a high-level potential driving voltage to the anode electrode from a high-level potential driving voltage source;

connecting a cathode electrode of the organic light-emitting diode device to a first node through the first switch element in response to a first scanning pulse from the first gate line;

connecting the data line to a second node through the second switch element in response to a second scanning pulse from the second gate line;

connecting the second node to a ground voltage source through the third switch element in response to an emission pulse from the emission line;

adjusting a current flowing between the cathode electrode of the organic light-emitting diode device and the second node through the driving element in accordance with a voltage on the first node; and

emitting light from the organic light-emitting diode device,

wherein the first and second scanning pulses are at an active logic voltage during a first period, and the first and second scanning pulses are maintained at the active logic voltage during a second period.

6. The method of driving an organic light-emitting diode display device as recited in claim 5 , wherein the emission pulse is maintained at a non-active logic voltage during the first and second periods.

7. The method of driving an organic light-emitting diode display device as recited in claim 5 , further comprising:

supplying a pre-charge voltage to the data line during the first period, the pre-charge voltage is defined by a difference voltage between the high-level potential driving voltage and the threshold voltage of the organic light-emitting diode device such that the pre-charge voltage is charged onto the first node by turning-on the second switch element during the first period.

8. The method of driving an organic light-emitting diode display device as recited in claim 5 , further comprising:

supplying an up-scaling current I data defined by the following equation to the data line during the second period such that the up-scaling current is charged onto the second node by turning-on the second switch element during the second period,

I

data

=

I

OLED

=

K

DR

⁡

(

Vgs

-

Vth

)

2

Vgs

=

I

data

K

DR

+

Vth

I OLED represents a current of the organic light-emitting diode device, Vgs represents a voltage applied between the gate electrode and the source electrode of the driving element, Vth represents a threshold voltage of the driving element and k DR represent a constant defined by mobility and a parasitic capacitance of the driving element.

9. The method of driving an organic light-emitting diode display device as recited in claim 8 , wherein the up-scaling current is generated as a current larger than an integer multiple of a current flowing into the organic light-emitting diode device; and the integer multiple in a lower gray scale of a digital video data is larger than that in a higher gray scale of a digital video data, the low gray scale is less than a predetermined reference gray scale and the high gray scale is equal or larger than the predetermined reference gray scale.

10. The method of driving an organic light-emitting diode display device as recited in claim 5 , further comprising:

changing the first and second scanning pulses into a non-active logic voltage during a third period, and maintained the first and second scanning pulses in a non-active logic voltage during a fourth period.

11. The method of driving an organic light-emitting diode display device as recited in claim 10 , wherein during the third period, the first and second switch elements are turned-off in response to the non-active voltages of the scanning pulses; and

a voltage Vgs between the gate and the source of the driving element is changed as much as ΔVgs defined by the following equation, and a current I OLED flowing into the organic light-emitting diode device is changed by the following equation,

Δ

⁢

⁢

Vgs

=

C

⁢

⁢

1

C

⁢

⁢

1

+

C

⁢

⁢

2

⁢

(

Δ

⁢

⁢

Vgate

⁢

⁢

2

-

Δ

⁢

⁢

Vs

)

I

OLED

=

k

DR

⁡

(

Vgs

-

Δ

⁢

⁢

Vgs

-

Vth

)

2

k DR represents a constant defined by mobility and a parasitic capacitance of the driving element, Vgs represents a voltage applied between the gate electrode and the source electrode of the driving element, ΔVgs represents a variation of Vgs, Vth represents a threshold voltage of the driving element, C 1 is a capacitance of the first capacitor, C 2 is a capacitance of the second capacitor, ΔVgate 2 represents a variation of a logic voltage of the second scanning pulse S 21 , and ΔVs represents a variation of a source voltage of the driving element.

12. The method of driving an organic light-emitting diode display device as recited in claim 10 , further comprising:

maintaining the emission pulse at a non-active logic voltage during the third period.

13. The method of driving an organic light-emitting diode display device as recited in claim 12 , further comprising:

changing the emission pulse into an active voltage during the fourth period.

14. The method of driving an organic light-emitting diode display device as recited in claim 13 , wherein the third switch element is turned-on in response to an active voltage of the emission pulse to electrically form a current path between the driving element and the ground voltage source during the fourth period.