Shift register unit, driving method thereof, shift register and display device

1. A shift register unit comprising a first capacitor, a pull-up module, a precharge module and a pull-down module, a first end of the first capacitor being coupled to the pull-up module at a pull-up node, the shift register unit further comprising:

a switch-off module coupled to the pull-up node and to a first node located between the precharge module and the pull-down module, configured to disconnect electrical connections (i) between the pull-up node and the precharge module and (ii) between the pull-up node and the pull-down module at a pull-up stage,

wherein the switch-off module comprises:

a first TFT, a source electrode of the first TFT is coupled to the first node, a gate electrode of the first TFT is coupled to a second clock signal input, and a drain electrode of the first TFT is coupled to the pull-up node; and

a switch-off controlling unit configured to control a source voltage of the first TFT at the pull-up stage so as to enable the first TFT to be in a fully off state, thereby to disconnect the electrical connections (i) between the pull-up node and the precharge module and (ii) between the pull-up node and the pull-down module.

2. The shift register unit according to claim 1 , wherein the switch-off controlling unit comprises:

a feedback capacitor, a first end of the feedback capacitor is coupled to the source electrode of the first TFT, and a second end of the feedback capacitor is coupled to the pull-up module and the pull-down module.

3. The shift register unit according to claim 1 , wherein the switch-off controlling unit further comprises:

a second TFT, a source electrode of the second TFT is coupled to the pull-up module and the pull-down module, a gate electrode of second TFT is coupled to a first clock signal input, and a drain electrode of second TFT is coupled to the source electrode of the first TFT.

4. The shift register unit according to claim 1 , wherein the switch-off controlling unit further comprises:

a second TFT, a source electrode of second TFT is coupled to the pull-up module and the pull-down module, a gate electrode of second TFT is coupled to the source electrode of the second TFT, and a drain electrode of second TFT is coupled to the source electrode of the first TFT.

5. The shift register unit according to claim 1 , wherein the switch-off controlling unit comprises a second TFT, and the switch-off module further comprises a third TFT,

the source electrode of the first TFT is coupled to a drain electrode of the second TFT and a drain electrode of the third TFT

a source electrode of the second TFT is coupled to the pull-up module and the pull-down module, and a gate electrode of the second TFT is coupled to a first clock signal input; and

a source electrode of the third TFT is coupled to the first node, and a gate electrode of the third TFT is coupled to the second clock signal input.

6. The shift register unit according to claim 1 , wherein the pull-up module comprises:

a fourth TFT, a source electrode of the fourth TFT is coupled to a first clock signal input, a gate electrode of the fourth TFT is coupled to the pull-up node, and a drain electrode of the fourth TFT is coupled to a second end of the first capacitor, the pull-down module and a signal output.

7. The shift register unit according to claim 1 , wherein the pull-up module comprises:

a fourth TFT and a fifth TFT,

wherein:

a source electrode of the fourth TFT is coupled to a source electrode of the fifth TFT and a first clock signal input;

a gate electrode of the fourth TFT is coupled to a gate electrode of the fifth TFT and the pull-up node;

a drain electrode of the fourth TFT is coupled to a gate signal output, a second end of the first capacitor and the pull-down module; and

a drain electrode of the fifth TFT is coupled to the switch-off module, the pull-down module and a start signal output.

8. The shift register unit according to claim 1 , wherein the precharge module comprises:

a sixth TFT, a source electrode and a gate electrode of the sixth TFT are coupled to a start signal input, and a drain electrode of the sixth TFT is coupled to the switch-off module and the pull-down module.

9. The shift register unit according to claim 1 , wherein the pull-down module comprises:

a seventh TFT, an eighth TFT, a ninth TFT, and a pull-down controlling unit configured to control an on or off state of the seventh, eighth and ninth TFTs,

wherein:

a source electrode of the seventh TFT is coupled to the precharge module and the switch-off module, a gate electrode of the seventh TFT is coupled to the pull-down controlling unit, a gate electrode of the eighth TFT and a gate electrode of the ninth TFT at a pull-down node, and a drain electrode of the seventh TFT is coupled to a first level signal input;

a source electrode of the eighth TFT is coupled to the pull-up module, the switch-off module and a start signal output, and a drain electrode of the eighth TFT is coupled to the first level signal input; and

a source electrode of the ninth TFT is coupled to the pull-up module, a second end of the first capacitor, and a gate signal output, and a drain electrode of the ninth TFT is coupled to a second level signal input.

10. The shift register unit according to claim 9 , wherein a potential of an input signal from the second level signal input is less than 0 and greater than a potential of an input signal from the first level signal input.

11. The shift register unit according to claim 9 , wherein the pull-down controlling unit comprises a tenth TFT and an eleventh TFT, wherein:

a source electrode and a gate electrode of the tenth TFT are coupled to the second clock signal input, and a drain electrode of the tenth TFT is coupled to the pull-down node, and

a drain electrode of the eleventh TFT is coupled to the pull-down node, a gate electrode of the eleventh TFT is coupled to a start signal input, and a source electrode of the eleventh TFT is coupled to the first level signal input.

12. The shift register unit according to claim 9 , wherein the pull-down controlling unit comprises a third capacitor and a tenth TFT, wherein:

a first end of the third capacitor is coupled to the second clock signal input, and a second end of the third capacitor is coupled to the pull-down node, and

a drain electrode of the tenth TFT is coupled to the pull-down node, a gate electrode of the tenth TFT is coupled to a start signal input, and a source electrode of the tenth TFT is coupled to the first level signal input.

13. The shift register unit according to claim 9 , wherein the pull-down controlling unit comprises a tenth TFT, an eleventh TFT, a twelfth TFT and a thirteenth TFT, wherein:

a source electrode and a gate electrode of the tenth TFT are coupled to the second clock signal input, and a drain electrode of the tenth TFT is coupled to a gate electrode of the eleventh TFT and a drain electrode of the twelfth TFT,

a source electrode of the eleventh TFT is coupled to the second clock signal input, and a drain electrode of the eleventh TFT is coupled to the pull-down node,

a gate electrode of the twelfth TFT is coupled to a start signal input and a gate electrode of the thirteenth TFT, and a source electrode of the twelfth TFT is coupled to the first level signal input and a source electrode of the thirteenth TFT, and

a drain electrode of the thirteenth TFT is coupled to the pull-down node.

14. A method for driving the shift register unit according to claim 1 , the method comprising:

at a precharge stage, pulling up a pull-up node and a first node to a first potential, and enabling a switch-off module to be in an on state;

at a pull-up stage, pulling up the pull-up node and the first node to a second potential greater than the first potential, enabling the switch-off module to be in a fully off state, and disconnecting electrical connections between the pull-up node and a precharge module and between the pull-up node and a pull-down module;

at a resetting stage, enabling the switch-off module to be in the on state, and pulling down the pull-up node and the first node to a third potential less than the first potential; and

at a resetting-maintaining stage, enabling the switch-off module to be in the off state, and maintaining the pull-up node and the first node at the third potential.

15. The method according to claim 14 , wherein:

at the precharge stage, a low level signal is input by a first clock signal input, a high level signal is input by the second clock signal input, and a high level signal is input by a start signal input;

at the pull-up stage, a high level signal is input by the first clock signal input, a low level signal is input by the second clock signal input, and a low level signal is input by the start signal input;

at the resetting stage, a low level signal is input by the first clock signal input, a high level signal is input by the second clock signal input, and a low level signal is input by the start signal input; and

at the resetting-maintaining stage, a high level signal is input by the first clock signal input, a low level signal is input by the second clock signal input, and a low level signal is input by the start signal input.

16. A display device, comprising multi-levels of shift register unit according to claim 1 .

17. A shift register unit comprising: a first capacitor, a pull-up module, a precharge module, and a pull-down module, a first end of the first capacitor being coupled to the pull-up module at a pull-up node, the shift register unit further comprising:

a switch-off module coupled to the pull-up node and to a first node located between the precharge module and the pull-down module, configured to disconnect electrical connections (i) between the pull-up node and the precharge module and (ii) between the pull-up node and the pull-down module at a pull-up stage;

wherein the switch-off module comprises:

a first TFT, a second TFT, and a third TFT,

wherein:

a source electrode of the first TFT is coupled to a drain electrode of the second TFT and a drain electrode of the third TFT, a gate electrode of the first TFT is coupled to a second clock signal input, and a drain electrode of the first TFT is coupled to the pull-up node;

a source electrode of the second TFT is coupled to the pull-up module and the pull-down module, and a gate electrode of the second TFT is coupled to a first clock signal input; and

a source electrode of the third TFT is coupled to the first node, and a gate electrode of the third TFT is coupled to the second clock signal input.