Organic light-emitting diode display device and pixel circuit thereof

1. An OLED pixel circuit, comprising:

a first switch transistor, a driving transistor and an OLED, wherein the first switch transistor, the driving transistor and the OLED are connected in series between a first operating voltage terminal and a second operating voltage terminal, the first switch transistor is controlled by a first signal, and a first terminal and a second terminal of the driving transistor are coupled to the first switch transistor and the OLED respectively, and the driving transistor has a control terminal;

a second switch transistor, coupled between the first terminal and the control terminal of the driving transistor and controlled by a second signal;

a third switch transistor, controlled according to a signal at a scan line to convey a signal from a data line to a circuit node;

a first capacitor, coupled between the circuit node and the control terminal of the driving transistor; and

a switch circuit, controlled according to a third signal to couple the second terminal of the driving transistor to a control voltage level,

wherein the first signal comprises a first stage enable interval and a second stage enable interval;

the first stage enable interval of the first signal is prior to an enable interval of the second signal;

the second stage enable interval of the first signal is later than a pixel data write interval;

an enable interval of the third signal cover the first stage enable interval of the first signal and the enable interval of the second signal; and

the control voltage level is fixed at a specific voltage level during the enable interval of the second signal to pull down a voltage level at the second terminal of the driving transistor.

2. The OLED pixel circuit as claimed in claim 1 , wherein the switch circuit comprises:

a fourth switch transistor, controlled according to the third signal to couple the second terminal of the driving transistor to the control voltage level,

wherein the specific voltage level for setting the control voltage level is provided by a reference power source or the first signal.

3. The OLED pixel circuit as claimed in claim 1 , wherein:

the enable interval of the third signal covers the pixel data write interval.

4. The OLED pixel circuit as claimed in claim 1 , wherein:

an enable interval of the signal at the scan line covers the first stage enable interval of the first signal, the enable interval of the second signal and the pixel data write interval; and

a voltage data of the specific voltage level is conveyed by the data line during the first stage enable interval of the first signal and the enable interval of the second signal and a pixel data is conveyed by the data line during the pixel data write interval.

5. The OLED pixel circuit as claimed in claim 1 , wherein the switch circuit comprises:

a fourth switch transistor, controlled according to the third signal to couple the circuit node to the control voltage level; and

a fifth switch transistor, controlled according to the third signal to couple the second terminal of the driving transistor to the control voltage level,

wherein the specific voltage level for setting the control voltage level is provided by a reference power source or the signal at the scan line.

6. The OLED pixel circuit as claimed in claim 1 , wherein the switch circuit comprises:

a fourth switch transistor, controlled according to the third signal to couple the circuit node to the control voltage level; and

a fifth switch transistor, controlled according to the third signal to couple the circuit node to the second terminal of the driving transistor,

wherein the specific voltage level for setting the control voltage level is provided by a reference power source or the signal at the scan line.

7. The OLED pixel circuit as claimed in claim 1 , wherein the switch circuit comprises:

a fourth switch transistor, controlled according to the third signal to coupled to the second terminal of the driving transistor to the control voltage level; and

a fifth switch transistor, controlled according to the third signal to couple the circuit node to the second terminal of the driving transistor,

wherein the specific voltage level for setting the control voltage level is provided by a reference power source or the signal at the scan line.

8. The OLED pixel circuit as claimed in claim 1 , further comprising:

a second capacitor, coupled between the second terminal of the driving transistor and the circuit node.

9. The OLED pixel circuit as claimed in claim 8 , wherein both the first and second capacitors are greater than a parasitic capacitor at the control terminal of the driving transistor.

10. The OLED pixel circuit as claimed in claim 1 , further comprising:

a coupling capacitor, coupled between the first terminal of the driving transistor and a control terminal of the second switch transistor.

11. The OLED pixel circuit as claimed in claim 1 , further comprising:

a coupling capacitor, coupling the first terminal of the driving transistor to the first operating voltage terminal or to the second operating voltage terminal or to a reference power source.

12. An OLED display device, comprising:

a pixel array, comprising the pixel circuit of claim 1 ;

a driver module, driving the pixel array; and

a microcontroller, controlling the driver module to drive the pixel array.