Scan driver and display device using the same

• US 9,595,219 B2
• Filed: 06/08/2015
• Issued: 03/14/2017
• Est. Priority Date: 06/13/2014
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Choi, Joungmi, Jang, Hyunguk, Shim, Dahye
• Primary Examiner(s): Sternbane, Larry
• Assistant Examiner(s): Michaud, Robert
• Application Number:
  US14/733,271
• Publication Number:
  US 20150364078A1
• Time in Patent Office: 645 Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2310/0286 Details of a shift registers arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/2092 Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165

Abstract

A scan driver and display device using the same are disclosed. The display device includes display panel, a data driver configured to supply a data signal to the display panel, and a scan driver formed in a non-display area of the display panel, including a shift register composed of a plurality of stages and a level shifter formed outside the display panel, and configured to supply a scan signal to the display panel using the shift register and the level shifter. The scan driver comprises: a sensor circuit unit configured to sense internal and external environmental conditions and generate a compensation circuit control signal on the basis of a sensed result; and a compensation circuit unit generating a compensation signal to compensate outputs of the plurality of stages in response to the compensation circuit control signal.

Claims

1. A display device, comprising:

a display panel;

a data driver configured to supply a data signal to the display panel; and

a scan driver formed in a non-display area of the display panel, including a shift register composed of a plurality of stages and a level shifter formed outside the display panel, and configured to supply a scan signal to the display panel using the shift register and the level shifter,

wherein the scan driver comprises;

a sensor circuit unit configured to sense internal and external environmental conditions and to generate a compensation circuit control signal on the basis of a sensed result; and

a compensation circuit unit configured to generate a compensation signal for compensating outputs of the plurality of stages in response to the compensation circuit control signal,

wherein the compensation circuit unit comprises a first transistor having a gate electrode and a first electrode connected to a first output terminal of the sensor circuit unit, and a second electrode connected to a compensation node of the compensation circuit unit.

2. The display device of claim 1, wherein the sensor circuit unit includes one of a temperature sensor for sensing the internal and external environmental conditions, a current sensor for sensing current flowing through a Q node or a QB node of an N-th stage, and a voltage sensor for sensing a voltage of the Q node or the QB node of the N-th stage.

3. The display device of claim 1, wherein the compensation circuit unit is configured to stably output a scan signal at a scan high voltage and a scan signal at a scan low voltage through output terminals of the plurality of stages.

4. The display device of claim 1, wherein the compensation circuit unit is configured to correspond to circuits for controlling Q nodes or QB nodes of the plurality of stages or composed of a number of transistors less than the number of transistors constituting the circuits for controlling Q nodes or QB nodes.

5. The display device of claim 1, wherein the compensation circuit unit further comprises:

a second transistor having a gate electrode connected to the compensation node, a first electrode connected to a low-level power line through which a low-level voltage is provided, and a second electrode connected to the Q node of the N-th stage;

a third transistor having a gate electrode connected to the Q node of the N-th stage, a first electrode connected to the low-level power line, and a second electrode connected to the compensation node; and

a fourth transistor having a gate electrode connected to the compensation node, a first electrode connected to the low-level power line, and a second electrode connected to an output terminal of the N-th stage.

6. The display device of claim 1, wherein the compensation circuit unit further comprises:

a second transistor having a gate electrode connected to a second output terminal of the sensor circuit unit, a first electrode connected to a low-level power line through which a low-level voltage is provided, and a second electrode connected to the compensation node;

a third transistor having a gate electrode connected to the compensation node and a first electrode connected to an (N−

1)-th clock signal line;

a fourth transistor having a gate electrode connected to a second electrode of the third transistor, a first electrode connected to an output terminal of an (N−

1)-th stage, and a second electrode connected to the Q node of the N-th stage;

a fifth transistor having a gate electrode connected to the compensation node and a first electrode connected to an (N+2)-th clock signal line; and

a sixth transistor having a gate electrode connected to a second electrode of the fifth transistor, a first electrode connected to the low-level power line, and a second electrode connected to the output terminal of the N-th stage.

7. The display device of claim 1, wherein the compensation circuit unit outputs the compensation signal when a compensation circuit control signal corresponding to a logic high is output from the sensor circuit unit, and does not output the compensation signal when a compensation circuit control signal corresponding to a logic low is output from the sensor circuit unit.

8. The display device of claim 1, wherein the compensation circuit unit outputs the compensation signal to stabilize a low-level voltage when an on current of transistors of the shift register decreases according to a low-temperature operation.

9. A scan driver, comprising:

a level shifter;

a shift register including a plurality of stages to generate a scan signal on the basis of a signal and power output from the level shifter;

a sensor circuit unit configured to sense internal and external environmental conditions of the shift register and generate a compensation circuit control signal on the basis of a sensed result; and

a compensation circuit unit generating a compensation signal to compensate outputs of the plurality of stages in response to the compensation circuit control signal,

wherein the compensation circuit unit comprises a first transistor having a gate electrode and a first electrode connected to a first output terminal of the sensor circuit unit, and a second electrode connected to a compensation node of the compensation circuit unit.

10. The scan driver of claim 9, wherein the sensor circuit unit includes one of a temperature sensor for sensing the internal and external environmental conditions, a current sensor for sensing current flowing through a Q node or a QB node of an N-th stage, and a voltage sensor for sensing a voltage of the Q node or the QB node of the N-th stage.

11. The scan driver of claim 9, wherein the compensation circuit unit is configured to stably output a scan signal at a scan high voltage and a scan signal at a scan low voltage through output terminals of the plurality of stages.

12. The scan driver of claim 9, wherein the compensation circuit unit is configured to correspond to circuits for controlling Q nodes or QB nodes of the plurality of stages or composed of a number of transistors less than the number of transistors constituting the circuits for controlling Q nodes or QB nodes.

13. The scan driver of claim 9, wherein the compensation circuit unit further comprises:

a second transistor having a gate electrode connected to the compensation node, a first electrode connected to a low-level power line through which a low-level voltage is provided, and a second electrode connected to the Q node of the N-th stage;

a third transistor having a gate electrode connected to the Q node of the N-th stage, a first electrode connected to the low-level power line, and a second electrode connected to the compensation node; and

a fourth transistor having a gate electrode connected to the compensation node, a first electrode connected to the low-level power line, and a second electrode connected to an output terminal of the N-th stage.

14. The scan driver of claim 9, wherein the compensation circuit unit further comprises:

a second transistor having a gate electrode connected to a second output terminal of the sensor circuit unit, a first electrode connected to a low-level power line through which a low-level voltage is provided, and a second electrode connected to the compensation node;

a third transistor having a gate electrode connected to the compensation node and a first electrode connected to an (N−

1)-th clock signal line;

a fourth transistor having a gate electrode connected to a second electrode of the third transistor, a first electrode connected to an output terminal of an (N−

1)-th stage, and a second electrode connected to the Q node of the N-th stage;

a fifth transistor having a gate electrode connected to the compensation node and a first electrode connected to an (N+2)-th clock signal line; and

a sixth transistor having a gate electrode connected to a second electrode of the fifth transistor, a first electrode connected to the low-level power line, and a second electrode connected to the output terminal of the N-th stage.

15. The scan driver of claim 9, wherein the compensation circuit unit outputs the compensation signal when a compensation circuit control signal corresponding to a logic high is output from the sensor circuit unit, and does not output the compensation signal when a compensation circuit control signal corresponding to a logic low is output from the sensor circuit unit.

16. The scan driver of claim 9, wherein the compensation circuit unit outputs the compensation signal to stabilize a low-level voltage when on current of transistors of the shift register decreases according to low-temperature operation.