OLED PIXEL DRIVING CIRCUIT AND OLED DISPLAY

• US 20200135107A1
• Filed: 11/01/2018
• Published: 04/30/2020
• Est. Priority Date: 06/21/2018
• Status: Active Grant

• Current Assignee: Wuhan China Star Optoelectronics Semiconductor Display Technology Co., Ltd. (TCL Technology Group Corp.)
• Original Assignee: Wuhan China Star Optoelectronics Semiconductor Display Technology Co., Ltd. (TCL Technology Group Corp.)
• Inventors: YAN, Weinan, LI, Jun
• Granted Patent: US 10,714,014 B2
• Time in Patent Office: Days
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0823 used to establish symmetry in driving, e.g. with polarity inversion
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element

Abstract

An organic light emitting diode (OLED) pixel driving circuit and an OLED display are provided. The OLED pixel driving circuit includes a first thin-film transistor (TFT), a second TFT, a third TFT, a fourth TFT, a fifth TFT, a sixth TFT, a capacitor, a first OLED, and a second OLED. A drain of the third TFT is connected to an anode of the first OLED, a cathode of the second OLED, and a source of the sixth TFT. A drain of the fifth TFT is connected to a cathode of the first OLED, an anode of the second OLED, and a source of the fourth TFT. A drain of the sixth TFT and a drain of the fourth TFT both receiving a power supply negative voltage.

Claims

1. An organic light emitting diode (OLED) pixel driving circuit, comprising:

a first thin-film transistor (TFT), a second TFT, a third TFT, a fourth TFT, a fifth TFT, a sixth TFT, a capacitor, a first OLED, and a second OLED;

a gate of the first TFT receiving a scanning signal;

a source of the first TFT receiving a data signal;

a drain of the first TFT connected to a gate of the second TFT and one terminal of the capacitor;

a source of the second TFT and the other terminal of the capacitor both receiving a power supply positive voltage;

a drain of the second TFT connected to a source of the third TFT and a source of the fifth TFT;

a gate of the third TFT, a gate of the fourth TFT, a gate of the fifth TFT, and a gate of the sixth TFT all receiving a controlling signal;

a drain of the third TFT connected to an anode of the first OLED, a cathode of the second OLED, and a source of the sixth TFT;

a drain of the fifth TFT connected to a cathode of the first OLED, an anode of the second OLED, and a source of the fourth TFT;

a drain of the sixth TFT and a drain of the fourth TFT both receiving a power supply negative voltage;

wherein the first TFT, the second TFT, the third TFT, and the fourth TFT are all N-type TFTs;

the fifth TFT and the sixth TFT are both P-type TFTs;

when a current frame of image is displayed, the controlling signal is at a high voltage level;

when a following frame of image is displayed, the controlling signal is at a low voltage level.

2. The OLED pixel driving circuit of claim 1, wherein the OLED pixel driving circuit further comprises a seventh TFT and an eighth TFT;

the controlling signal comprises a first controlling signal and a second controlling signal;

the data signal comprises a first data signal and a second data signal;

a gate of the seventh TFT receives the first controlling signal;

a source of the seventh TFT receives the first data signal;

a gate of the eighth TFT receives a second controlling signal;

a source of the eighth TFT receives a second data signal;

the source of the first TFT is connected to a drain of the seventh TFT and a drain of the eighth TFT;

the gate of the third TFT and the gate of the fourth TFT both receive the first controlling signal;

the gate of the fifth TFT and the gate of the sixth TFT T6 both receive the second controlling signal.

3. The OLED pixel driving circuit of claim 2, wherein the seventh TFT and the eighth TFT are both N-type TFTs.

4. The OLED pixel driving circuit of claim 2, wherein when the current frame of image is displayed, the first controlling signal is at a high voltage level and the second controlling signal is at a low voltage level;

when the following frame of image is displayed, the second controlling signal is at a high voltage level and the first controlling signal is at a low voltage level.

5. The OLED pixel driving circuit of claim 2, wherein the first controlling signal and the second controlling signal are both signals with a square wave;

the period of the first controlling signal is the same as the period of the second controlling signal;

the polarity of the first controlling signal is opposite to the polarity of the second controlling signal.

6. The OLED pixel driving circuit of claim 2, wherein the first data signal and the second data signal are set according to the brightness of the first OLED and the brightness of the second OLED at the same grayscale level;

the brightness of the first OLED is the same as the brightness of the second OLED at the same grayscale level.

7. The OLED pixel driving circuit of claim 1, wherein the first TFT, the second TFT, the third TFT, the fourth TFT, the fifth TFT, and the sixth TFT all are low temperature polysilicon TFTs, oxide semiconductor TFTs, or amorphous silicon (a-Si) TFTs arbitrarily.

8. An organic light emitting diode (OLED) pixel driving circuit, comprising:

a first thin-film transistor (TFT), a second TFT, a third TFT, a fourth TFT, a fifth TFT, a sixth TFT, a capacitor, a first OLED, and a second OLED;

a gate of the first TFT receiving a scanning signal;

a source of the first TFT receiving a data signal;

a drain of the first TFT connected to a gate of the second TFT and one terminal of the capacitor;

a source of the second TFT and the other terminal of the capacitor both receiving a power supply positive voltage;

a drain of the second TFT connected to a source of the third TFT and a source of the fifth TFT;

a gate of the third TFT, a gate of the fourth TFT, a gate of the fifth TFT, and a gate of the sixth TFT all receiving a controlling signal;

a drain of the third TFT connected to an anode of the first OLED, a cathode of the second OLED, and a source of the sixth TFT;

a drain of the fifth TFT connected to a cathode of the first OLED, an anode of the second OLED, and a source of the fourth TFT;

a drain of the sixth TFT and a drain of the fourth TFT both receiving a power supply negative voltage.

9. The OLED pixel driving circuit of claim 8, wherein the first TFT, the second TFT, the third TFT, and the fourth TFT are all N-type TFTs;

the fifth TFT and the sixth TFT are both P-type TFTs.

10. The OLED pixel driving circuit of claim 8, wherein when a current frame of image is displayed, the controlling signal is at a high voltage level;

when a following frame of image is displayed, the controlling signal is at a low voltage level.

11. The OLED pixel driving circuit of claim 8, wherein the OLED pixel driving circuit further comprises a seventh TFT and an eighth TFT;

the controlling signal comprises a first controlling signal and a second controlling signal;

the data signal comprises a first data signal and a second data signal;

a gate of the seventh TFT receives the first controlling signal;

a source of the seventh TFT receives the first data signal;

a gate of the eighth TFT receives a second controlling signal;

a source of the eighth TFT receives a second data signal;

the source of the first TFT is connected to a drain of the seventh TFT and a drain of the eighth TFT;

the gate of the third TFT and the gate of the fourth TFT both receive the first controlling signal;

the gate of the fifth TFT and the gate of the sixth TFT T6 both receive the second controlling signal.

12. The OLED pixel driving circuit of claim 11, wherein the seventh TFT and the eighth TFT are both N-type TFTs.

13. The OLED pixel driving circuit of claim 11, wherein when the current frame of image is displayed, the first controlling signal is at a high voltage level and the second controlling signal is at a low voltage level;

when the following frame of image is displayed, the second controlling signal is at a high voltage level and the first controlling signal is at a low voltage level.

14. The OLED pixel driving circuit of claim 13, wherein the first controlling signal and the second controlling signal are both signals with a square wave;

the period of the first controlling signal is the same as the period of the second controlling signal;

the polarity of the first controlling signal is opposite to the polarity of the second controlling signal.

15. The OLED pixel driving circuit of claim 11, wherein the first data signal and the second data signal are set according to the brightness of the first OLED and the brightness of the second OLED at the same grayscale level;

the brightness of the first OLED is the same as the brightness of the second OLED at the same grayscale level.

16. The OLED pixel driving circuit of claim 8, wherein the first TFT, the second TFT, the third TFT, the fourth TFT, the fifth TFT, and the sixth TFT all are low temperature polysilicon TFTs, oxide semiconductor TFTs, or amorphous silicon (a-Si) TFTs arbitrarily.

17. An organic light emitting diode (OLED) display, comprising an OLED pixel driving circuit, the OLED pixel driving circuit comprising:

a first thin-film transistor (TFT), a second TFT, a third TFT, a fourth TFT, a fifth TFT, a sixth TFT, a capacitor, a first OLED, and a second OLED;

a gate of the first TFT receiving a scanning signal;

a source of the first TFT receiving a data signal;

a drain of the first TFT connected to a gate of the second TFT and one terminal of the capacitor;

a source of the second TFT and the other terminal of the capacitor both receiving a power supply positive voltage;

a drain of the second TFT connected to a source of the third TFT and a source of the fifth TFT;

a gate of the third TFT, a gate of the fourth TFT, a gate of the fifth TFT, and a gate of the sixth TFT all receiving a controlling signal;

a drain of the third TFT connected to an anode of the first OLED, a cathode of the second OLED, and a source of the sixth TFT;

a drain of the fifth TFT connected to a cathode of the first OLED, an anode of the second OLED, and a source of the fourth TFT;

a drain of the sixth TFT and a drain of the fourth TFT both receiving a power supply negative voltage.

18. The OLED display of claim 17, wherein the first TFT, the second TFT, the third TFT, and the fourth TFT are all N-type TFTs;

the fifth TFT and the sixth TFT are both P-type TFTs.

19. The OLED display of claim 17, wherein when a current frame of image is displayed, the controlling signal is at a high voltage level;

when a following frame of image is displayed, the controlling signal is at a low voltage level.

20. The OLED display of claim 17, wherein the OLED pixel driving circuit further comprises a seventh TFT and an eighth TFT;

the controlling signal comprises a first controlling signal and a second controlling signal;

the data signal comprises a first data signal and a second data signal;

a gate of the seventh TFT receives the first controlling signal;

a source of the seventh TFT receives the first data signal;

a gate of the eighth TFT receives a second controlling signal;

a source of the eighth TFT receives a second data signal;

the source of the first TFT is connected to a drain of the seventh TFT and a drain of the eighth TFT;

the gate of the third TFT and the gate of the fourth TFT both receive the first controlling signal;

the gate of the fifth TFT and the gate of the sixth TFT T6 both receive the second controlling signal.