Driving circuit for full-color organic light-emitting diode pixel and driving method of the driving circuit

• US 10,102,805 B2
• Filed: 11/10/2015
• Issued: 10/16/2018
• Est. Priority Date: 05/13/2015
• Status: Active Grant

• Current Assignee: Beijing BOE Optoelectronics Technology Co Ltd. (BOE Technology Group Co., Ltd.), BOE Technology Group Co., Ltd.
• Original Assignee: Beijing BOE Optoelectronics Technology Co Ltd. (BOE Technology Group Co., Ltd.), BOE Technology Group Co., Ltd.
• Inventors: Yang, Shengji, Dong, Xue, Wang, Haisheng, Li, Changfeng, Liu, Wei, Liu, Yingming, Liu, Peng, Xue, Hailin
• Primary Examiner(s): Lee, Jr., Kenneth B
• Application Number:
  US15/037,746
• Publication Number:
  US 20170132976A1
• Time in Patent Office: 1,071 Days
• Field of Search: None
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• CPC Class Codes: G09G 2300/0871 with level shifting
• CPC Class Codes: G09G 2310/0245 Clearing or presetting the whole screen independently of waveforms, e.g. on power-on G09G2310/063 takes precedence
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• 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
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths

Abstract

A driving circuit for a full-color OLED pixel and a driving method of the driving circuit. The full-color OLED pixel comprises at least two color thin film layers stacked (Color1, Color2, Color3) and insulating layers (Ins1, Ins2) arranged between any two adjacent thin film layers. The driving circuit comprises at least two driving sub-circuits, the at least two driving sub-circuits share a data line (DATA) and a light-emitting control terminal (EM), and each of the driving sub-circuits is connected to a scanning control terminal corresponding thereto (SCAN1, SCAN2, SCAN3) and is configured to drive the color thin film layer corresponding thereto. The at least two driving sub-circuits read data signals on the data line in sequence under the control of the respective scanning control terminals, and drive the respective color thin film layers to emit light concurrently under the control of the light-emitting control terminal. Full-color display of the full-color OLED pixel is achieved by reading in sequence corresponding data signals for the at least two color thin film layers stacked and controlling the at least two color thin film layers to emit light concurrently.

Claims

1. A driving circuit for a full-color OLED pixel comprising at least two color thin film layers stacked and insulating layers arranged between any two adjacent thin film layers, comprising:

at least two driving sub-circuits which share a data line and a light-emitting control terminal, each of the driving sub-circuits connected to a scanning control terminal corresponding thereto and configured to drive the color thin film layer corresponding thereto,

wherein the at least two driving sub-circuits read data signals on the data line in sequence under the control of the respective scanning control terminals, and drive the respective color thin film layers to emit light concurrently under the control of the light-emitting control terminal,

wherein the at least two color thin film layers comprise a first color thin film layer, a second color thin film layer and a third color thin film layer, and

the at least two driving sub-circuits comprise;

a first driving sub-circuit connected to a first scanning control terminal, the data line and the light-emitting control terminal and configured to drive the first color thin film layer;

a second driving sub-circuit connected to a second scanning control terminal, the data line and the light-emitting control terminal and configured to drive the second color thin film layer; and

a third driving sub-circuit connected to a third scanning control terminal, the data line and the light-emitting control terminal and configured to drive the third color thin film layer,

wherein the first driving sub-circuit, the second driving sub-circuit and the third driving sub-circuit read the data signals on the data line in sequence under the control of the first scanning control terminal, the second scanning control terminal and the third scanning control terminal; and

the first driving sub-circuit, the second driving sub-circuit and the third driving sub-circuit drive the first color thin film layer, the second color thin film layer and the third color thin film layer respectively to emit light concurrently under the control of the light-emitting control terminal.

2. The driving circuit of claim 1, wherein each of the driving sub-circuits comprises:

a data-reading module for reading and storing a data signal on the data line, and

a light-emitting driving module for driving a color thin film layer corresponding thereto to emit light.

3. The driving circuit of claim 2, wherein the data-reading module is further configured to store a threshold voltage of a driving transistor in the light-emitting driving module, and the data-reading module comprises:

a first switching transistor having a gate connected to the first scanning control terminal, a first electrode connected to the data line and a second electrode connected to a second electrode of the driving transistor;

a second switching transistor having a gate connected to the first scanning control terminal and a second electrode connected to a first electrode of the driving transistor; and

a capacitor having a first electrode connected to a first electrode of the second switching transistor and a second electrode connected to a first level supply terminal.

4. The driving circuit of claim 3, wherein the light-emitting driving module comprises:

a third switching transistor having a gate connected to the light-emitting control terminal, a first electrode connected to the first level supply terminal, and a second electrode connected to the first electrode of the driving transistor and the second electrode of the second switching transistor;

a fourth switching transistor having a gate connected to the light-emitting control terminal, a first electrode connected to the second electrode of the driving transistor, and a second electrode connected to a first electrode of the color thin film layer corresponding thereto; and

the driving transistor having a gate connected to the first electrode of the capacitor.

5. The driving circuit of claim 2, wherein the at least two driving sub-circuits further share a resetting control terminal, and each of the driving sub-circuits further comprises:

a resetting module for resetting the data-reading module in the driving sub-circuit to its initial state under the control of the resetting control terminal.

6. The driving circuit of claim 5, wherein the resetting module comprises:

a fifth switching transistor having a gate connected to the resetting control terminal, a first electrode connected to the first electrode of the capacitor and the gate of the driving transistor, and a second electrode connected to a second level supply terminal.

7. The driving circuit of claim 6, wherein

the first level supply terminal is a high level supply terminal, the second level supply terminal is a low level supply terminal;

and

for each of the color thin film layers, the first electrode is an anode, and the second electrode is a cathode and is connected to the second level supply terminal.

18. A full-color OLED display comprising an array of full-color OLED pixels, wherein each of the full-color OLED pixels comprises the driving circuit of the full-color OLED pixel of claim 1.

8. A driving method of a driving circuit of a full-color OLED pixel comprising at least two color thin film layers stacked and insulating layers arranged between any two adjacent thin film layers, the driving circuit comprising at least two driving sub-circuits which share a data line and a light-emitting control terminal and each of which is connected to a scanning control terminal corresponding thereto and is configured to drive the color thin film layer corresponding thereto, the driving method comprising:

during a data-reading period, the at least two driving sub-circuits reading data signals on the data line in sequence under the control of the respective scanning control terminals; and

during a light-emitting period, the at least two driving sub-circuits driving the respective color thin film layers respectively to emit light concurrently under the control of the light-emitting control terminal,

wherein the at least two color thin film layers comprise a first color thin film layer, a second color thin film layer and a third color thin film layer, and the at least two driving sub-circuits comprise a first driving sub-circuit, a second driving sub-circuit and a third driving sub-circuit, the first driving sub-circuit is connected to a first scanning control terminal, the data line and the light-emitting control terminal, the second driving sub-circuit is connected to a second scanning control terminal, the data line and the light-emitting control terminal, and the third driving sub-circuit is connected to a third scanning control terminal, the data line and the light-emitting control terminal,

wherein the at least two driving sub-circuits reading data signals on the data line in sequence under the control of the respective scanning control terminals during the data-reading period comprises;

during a first data-reading period, the first driving sub-circuit reading and storing a first data signal on the data line under the control of the first scanning control terminal;

during a second data-reading period, the second driving sub-circuit reading and storing a second data signal on the data line under the control of the second scanning control terminal; and

during a third data-reading period, the third driving sub-circuit reading and storing a third data signal on the data line under the control of the third scanning control terminal,

wherein the at least two driving sub-circuits driving the respective color thin film layers respectively to emit light concurrently under the control of the light-emitting control terminal during the light-emitting period comprises;

during the light-emitting period, the first driving sub-circuit, the second driving sub-circuit and the third driving sub-circuit drive the first color thin film layer, the second color thin film layer and the third color thin film layer respectively to emit light concurrently under the control of the light-emitting control terminal.

9. The driving method of claim 8, after the light-emitting period or before the data-reading period, the driving method further comprises:

during a resetting period, resetting each of the at least two driving sub-circuit to its initial state.

10. The driving method of claim 8, wherein

during the first data-reading period, the first scanning control terminal is at a low level, the second scanning control terminal and the third scanning control terminal are at a high level, and the light-emitting control terminal is at a high level;

during the second data-reading period, the second scanning control terminal is at a low level, the first scanning control terminal and the third scanning control terminal are at a high level, and the light-emitting control terminal is at a high level;

during the third data-reading period, the third scanning control terminal is at a low level, the first scanning control terminal and the second scanning control terminal are at a high level, and the light-emitting control terminal is at a high level; and

during the light-emitting period, the first scanning control terminal, the second scanning control terminal and the third scanning control terminal are at a high level, and the light-emitting control terminal is at a low level.

11. The driving method of claim 9, wherein the at least two driving sub-circuits further share a resetting control terminal, the resetting control terminal is at a low level during a resetting period and is at a high level during the data-reading period and the light-emitting period, wherein

during the resetting period, the respective scanning control terminals and the light-emitting control terminal are at a high level.

12. The driving method of claim 8, wherein each of the driving sub-circuits comprises a data-reading module and a light-emitting driving module,

the data-reading module comprises:

a first switching transistor having a gate connected to the first scanning control terminal, a first electrode connected to the data line and a second electrode connected to a second electrode of a driving transistor in the light-emitting driving module;

a second switching transistor having a gate connected to the first scanning control terminal and a second electrode connected to a first electrode of the driving transistor; and

a capacitor having a first electrode connected to a first electrode of the second switching transistor and a second electrode connected to a first level supply terminal;

the light-emitting driving module comprises;

a third switching transistor having a gate connected to the light-emitting control terminal, a first electrode connected to the first level supply terminal, and a second electrode connected to the first electrode of the driving transistor and the second electrode of the second switching transistor;

a fourth switching transistor having a gate connected to the light-emitting control terminal, a first electrode connected to the second electrode of the driving transistor, and a second electrode connected to a first electrode of the color thin film layer corresponding thereto; and

the driving transistor having a gate connected to the first electrode of the capacitor.

13. The driving method of claim 12, wherein the driving sub-circuits share a resetting control terminal, and each of the driving sub-circuits further comprises a resetting module for resetting the data-reading module to its initial state,

the resetting module comprises a fifth switching transistor having a gate connected to the resetting control terminal, a first electrode connected to the first electrode of the capacitor and the gate of the driving transistor, and a second electrode connected to a second level supply terminal.

14. The driving method of claim 12, wherein the at least two color thin film layers comprise a first color thin film layer, a second color thin film layer and a third color thin film layer, and the at least two driving sub-circuits comprise a first driving sub-circuit, a second driving sub-circuit and a third driving sub-circuit, the first driving sub-circuit is connected to a first scanning control terminal, the data line and the light-emitting control terminal, the second driving sub-circuit is connected to a second scanning control terminal, the data line and the light-emitting control terminal, and a third driving sub-circuit is connected to a third scanning control terminal, the data line and the light-emitting control terminal,

wherein the at least two driving sub-circuits reading data signals on the data line in sequence under the control of the respective scanning control terminals during the data-reading period comprises:

during a first data-reading period, the first scanning control terminal is at a low level, the second scanning control terminal and the third scanning control terminal are at a high level, and the light-emitting control terminal is at a high level, a data signal on the data line is a first data signal, the first switching transistor and the second switching transistor in the first driving sub-circuit are turned on, the driving transistor in the first driving sub-circuit is turned on such that the capacitor stores the first data signal and the threshold voltage of the driving transistor;

during the second data-reading period, the second scanning control terminal is at a low level, the first scanning control terminal and the third scanning control terminal are at a high level, and the light-emitting control terminal is at a high level, a data signal on the data line is a second data signal, such that the capacitor in the second driving sub-circuit stores the second data signal and the threshold voltage of the driving transistor in the second driving sub-circuit, the capacitor in the first driving sub-circuit keeps the voltage across its two electrodes unchanged;

during the third data-reading period, the third scanning control terminal is at a low level, the first scanning control terminal and the second scanning control terminal are at a high level, and the light-emitting control terminal is at a high level, a data signal on the data line is a third data signal, such that the capacitor in the third driving sub-circuit stores the third data signal and the threshold voltage of the driving transistor in the third driving sub-circuit, the capacitor in the first driving sub-circuit keeps the voltage across its two electrodes unchanged and the capacitor in the second driving sub-circuit keeps the voltage across its two electrodes unchanged;

wherein the at least two sub-circuits driving the respective color thin film layers to emit light concurrently under the control of the light-emitting control terminal during the light-emitting period comprises;

during the light-emitting period, the first scanning control terminal, the second scanning control terminal and the third scanning control terminal are at a high level, and the light-emitting control terminal is at a low level, the driving transistor in the first driving sub-circuit is turned on and drives the first color thin film layer to emit light, the driving transistor in the second driving sub-circuit is turned on and drives the second color thin film layer to emit light, and the driving transistor in the third driving sub-circuit is turned on and drives the third color thin film layer to emit light.

15. The driving method of claim 13, wherein

during the resetting period, the respective scanning control terminals and the light-emitting control terminal are at a high level, the resetting control terminal is at a low level, the fifth switching transistor in the resetting module of each of the driving sub-circuits is turned on, such that a voltage of the first electrode of the capacitor in each of the driving sub-circuits is reset to a voltage at the second level supply terminal.

16. The driving method of claim 14, wherein

for each of the driving sub-circuits, during the data-reading period corresponding thereto, a first current origins from the data line, flows through the first switching transistor, the driving transistor and the second switching transistor in sequence, and arrives at the first electrode of the capacitor in the driving sub-circuit;

and during the light-emitting period, a second current origins from the first level supply terminal, flows through the third switching transistor, the driving transistor and the fourth switching transistor in sequence, and arrives at the first electrode of the color thin film layer corresponding to the driving sub-circuit.

17. The driving method of claim 16, wherein

for each of the driving sub-circuits, during the data-reading period corresponding thereto, the first current flows from the second electrode of the driving transistor to the first electrode of the driving transistor, during the light-emitting period, the second current flows from the first electrode of the driving transistor to the second electrode of the driving transistor;

and

for each of the driving sub-circuits, during the light-emitting period, the color thin film layer corresponding thereto is driven to emit light by the data voltage corresponding thereto and the threshold voltage of the driving transistor corresponding thereto stored by the capacitor in the driving sub-circuit, so as to compensate for effect of drift of the threshold voltage of the driving transistor on luminance of the color thin film layer.