A DRIVING SYSTEM FOR A DISPLAY DEVICE, AND DRIVING CIRCUIT APPLICABLE TO OLED

• US 20180158401A1
• Filed: 10/10/2015
• Published: 06/07/2018
• Est. Priority Date: 09/15/2015
• Status: Active Grant

• Current Assignee: Shenzhen China Star Optoelectronics Technology Co., Ltd. (TCL Technology Group Corp.)
• Original Assignee: Shenzhen China Star Optoelectronics Technology Co., Ltd. (TCL Technology Group Corp.)
• Inventors: WANG, Zhenling, HWANG, Tai Jiun
• Granted Patent: US 10,319,292 B2
• Time in Patent Office: Days
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat panels
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

Provided is a driving system for a display device and a driving circuit applicable to an OLED, which belong to the field of display technology, and can eliminate the phenomenon of shortening in lifetime of the OLED caused by a long-term DC bias light-emitting state of the OLED.

Claims

1. A driving circuit applicable to an OLED, which includes a driving unit connected to a scan line and a data line for driving the OLED, and a reverse bias unit connected to the OLED,

wherein the reverse bias unit is used for controlling reverse bias of the OLED when a black picture is inserted between two image frames.

2. The driving circuit according to claim 1, wherein the driving unit includes a first transistor, a second transistor, and a storage capacitor,

wherein an output terminal of the first transistor is connected to a first terminal of the storage capacitor and a control terminal of the second transistor;

wherein a second terminal of the storage capacitor is connected to a first driving signal; and

wherein an output terminal of the second transistor is connected to an anode of the OLED, a cathode of which is connected to a cathode driving signal.

3. The driving circuit according to claim 2, wherein the cathode driving signal is switched between a first level and a second level,

wherein the first level is equal to a high level of the first driving signal, and higher than the second level.

4. The driving circuit according to claim 3, wherein the reverse bias unit includes a third transistor and a fourth transistor,

wherein the third transistor has a control terminal, an input terminal, and an output terminal respectively connected to a first control signal, a second terminal of the storage capacitor, and an input terminal of the second transistor,

wherein the fourth transistor has a control terminal, an input terminal, and an output terminal respectively connected to a second control signal, the anode of the OLED, and a second driving signal,

wherein the second driving signal has an amplitude lower than that of the first driving signal, but higher than that of a signal connected to the control terminal of the second transistor, and

wherein the second transistor and the OLED are reversely biased when the third transistor and the fourth transistor are respectively deactivated and activated, and the cathode driving signal is at the second level.

5. A driving system of a display device, the driving system comprising a driving circuit, which includes a driving unit connected to a scan line and a data line for driving the OLED, and a reverse bias unit connected to the OLED, wherein the reverse bias unit is used for controlling reverse bias of the OLED when a black picture is inserted between two image frames;

and the driving system further comprising;

a processing unit, which caches a data signal from a signal source, performs frame multiplication on the data signal by insertion of a black picture between two adjacent data signal frames, and outputs a frame multiplied data signal to a display panel; and

a control unit, which outputs a reverse bias signal when the processing unit outputs a data signal corresponding to the black picture,

wherein the reverse bias unit of the driving circuit is configured to control reverse bias of the OLED and a driving transistor according to the reverse bias signal.

6. The driving system according to claim 5, wherein the reverse bias signal comprises a first control signal and a second control signal,

wherein the first control signal is supplied to a control terminal of a third transistor in the reverse bias unit, and the second control signal is supplied to a control terminal of a fourth transistor.

7. The driving system according to claim 6, wherein the first control signal and the second control signal have a same frequency and opposite phases.

8. The driving system according to claim 5, wherein the reverse bias signal further comprises a cathode driving signal which is switched between a first level and a second level, the first level being higher than the second level;

and

wherein the cathode driving signal is at a high level when the processing unit outputs the data signal corresponding to the black picture.

9. The driving system according to claim 5, further comprising:

an analysis unit, which analyzes an average image level frame-by-frame; and

a gamma voltage unit, which outputs a first gamma voltage when the average image level output from the analysis unit is higher than a preset value, or otherwise, outputs a second gamma voltage which is higher than the first gamma voltage.