IP Library Granted Patent US 7,532,701
Granted Patent B2
US 7,532,701 · App. 11/826,917 · Granted May 12, 2009

Shift register and driving method thereof

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Quick Facts
Patent No.
US 7,532,701
App. No.
11/826,917
Granted
May 12, 2009
Kind
B2
Abstract

A shift register having a plurality of stages for shifting a start pulse and outputting a shifted start pulse to a next stage, each of the plurality of stages includes a pull-up transistor controlled by a first node to apply a first clock signal to an output line, a first pull-down transistor controlled by a second node to apply a first driving voltage to the output line, a controller for controlling the first and second nodes, and a compensating capacitor connected between the first node and an input line of a second clock signal, the second clock signal being different from the first clock signal.

Claims (44)

1. A shift register having a plurality of stages for shifting a start pulse and outputting a shifted start pulse to a next stage, each of the plurality of stages comprising:

a pull-up transistor controlled by a first node to apply a first clock signal to an output line;

a first pull-down transistor controlled by a second node to apply a first driving voltage to the output line;

a controller for controlling the first and second nodes; and

a compensating capacitor connected between the first node and an input line of a second clock signal, the second clock signal being different from the first clock signal,

wherein the controller includes:

a first transistor for applying the start pulse to the first node in response to the second clock signal;

a second transistor for applying a second driving voltage to the second node in response to the second clock signal;

a third transistor for applying the first driving voltage to the second node in response to the first clock signal; and

a fourth transistor for applying the first driving voltage to the third transistor in response to a voltage at the first node.

2. The shift register according to claim 1 , wherein the compensating capacitor has a capacitance greater than the parasitic capacitor.

3. The shift register according to claim 1 , wherein the shift register is formed on a glass substrate.

4. The shift register according to claim 1 , each of the stages further comprising:

a second pull-down transistor controlled by a third node and connected in parallel to the first pull-down transistor between the output line and a supply line of the first driving voltage.

5. A shift register having a plurality of stages for shifting a start pulse and outputting a shifted start pulse to a next stage, each of the plurality of stages comprising: a pull-up transistor controlled by a first node to apply a first clock signal to an output line; a first pull-down transistor controlled by a second node to apply a first driving voltage to the output line; a controller for controlling the first and second nodes; and a compensating capacitor connected between the first node and an input line of a second clock signal, the second clock signal being different from the first clock signal, wherein the controller includes:

a first node controller for applying the start pulse to the first node in response to the second clock signal;

a second node controller for selectively applying a voltage at a fourth node and the first driving voltage in response to the first clock signal and the second clock signal;

a third node controller for applying the voltage at the fourth node and the second driving voltage to a third node in response to the first clock signal and the second clock signal; and

a fourth node controller for selectively applying the first and second driving voltages to the fourth node in response to the first clock signal, the second clock signal and a voltage at the first node.

6. The shift register according to claim 5 , wherein the first node controller includes a first transistor for applying the start pulse to the first node in response to the second clock signal.

7. The shift register according to claim 5 , wherein the fourth node controller includes:

a second transistor for applying a second driving voltage to the fourth node in response to the second clock signal;

a third transistor for applying the second driving voltage to the fourth node in response to the first clock signal; and

a fourth transistor for applying the first driving voltage to the fourth node in response to a voltage at the first node.

8. A method of driving a shift register having a plurality of stages for shifting a start pulse and outputting a shifted start pulse to a next stage, each of the plurality of stages comprising a pull-up transistor controlled by a first node to apply a first clock signal to an output line, a first pull-down transistor controlled by a second node to apply a first driving voltage to the output line, a controller for controlling the first and second nodes, and a compensating capacitor connected between the first node and an input line of a second clock signal, the second clock signal being different from the first clock signal, comprising:

floating the first node;

wherein the controller includes:

a first transistor for applying the start pulse to the first node in response to the second clock signal;

a second transistor for applying a second driving voltage to the second node in response to the second clock signal;

a third transistor for applying the first driving voltage to the second node in response to the first clock signal; and

a fourth transistor for applying the first driving voltage to the third transistor in response to a voltage at the first node.

9. A driving device for a liquid crystal display panel device, comprising:

a shift register having a plurality of stages for shifting a start pulse and outputting a shifted start pulse to a next stage, each of the plurality of stages including:

a pull-up transistor controlled by a first node to apply a first clock signal to an output line;

a first pull-down transistor controlled by a second node to apply a first driving voltage to the output line;

a controller for controlling the first and second nodes; and

a compensating capacitor connected between the first node and an input line of a second clock signal, the second clock signal being different from the first clock signal,

wherein the controller includes:

a first transistor for applying the start pulse to the first node in response to the second clock signal;

a second transistor for applying a second driving voltage to the second node in response to the second clock signal;

a third transistor for applying the first driving voltage to the second node in response to the first clock signal; and

a fourth transistor for applying the first driving voltage to the third transistor in response to a voltage at the first node.

10. The driving device according to claim 9 , wherein the shift register is formed on a glass substrate.

11. The driving device according to claim 9 , wherein the output line of each of the plurality of stages is connected to a gate line of a liquid crystal display panel.

Assignments (1)
CHANGE OF NAME Recorded Jun 19, 2008
From: LG.PHILIPS LCD CO., LTD.
To: LG DISPLAY CO., LTD.
Reel/Frame 021147/0009 →