Shift register and liquid crystal display device using same

• US 20080158133A1
• Filed: 12/27/2007
• Published: 07/03/2008
• Est. Priority Date: 12/29/2006
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: Innolux Display Corporation (InnoLux Corporation)
• Inventors: Ieong, Man-Fai, Chen, Sz-Hsiao
• Granted Patent: US 7,986,761 B2
• Time in Patent Office: Days
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/0286 Details of a shift registers arranged for use in a driving circuit
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: G11C 19/00 Digital stores in which the information is moved stepwise, e.g. shift registers
• CPC Class Codes: G11C 19/28 using semiconductor elements G11C19/14, G11C19/36 take precedence

Abstract

An exemplary shift register (20) includes shift register units (S1˜Sn). The shift register units receive a clock signal and an inverse clock signal and output a plurality of shift register signals in sequence. An output of previous adjacent one of the shift register units is an input of the shift register unit.

Claims

1. A shift register for providing a plurality of low level shift register signals, the shift register comprising:

a plurality of shift register units connected in series, each shift register unit comprising a first inversion circuit, a second inversion circuit, and a third inversion circuit;

the first inversion circuit being configured for providing a second output signal according to a clock signal from an external circuit and a first output signal from the third inversion circuit;

the second inversion circuit being configured for providing a control signal according to a first output signal from a previous adjacent one of the shift register units and a second output signal from the previous adjacent shift register unit, except in the case of a first one of the shift register units, wherein the second inversion circuit is configured for providing a control signal according to a first external output signal from an external circuit and a second external out put signal from an external circuit;

the third inversion circuit being configured for providing the first output signal and a shift register signal according to the control signal, the second output signal and an inverse clock signal from the external circuit;

wherein the two first inversion circuits of adjacent shift register units respectively receive the clock signal and the inverse clock signal, the two third inversion circuits of adjacent shift register units respectively receive the clock signal and the inverse clock signal, and the first shift register unit receives a start signal from an external circuit to start the shift register.

2. The shift register in claim 1, wherein the first inversion circuit comprises a first transistor and a second transistor, the source of the first transistor being coupled to a high level voltage, the drain of the first transistor being coupled to the drain of the second transistor, the gate of the first transistor being coupled to the third inversion circuit, the source of the second transistor being coupled to a low level voltage, the gate of the second transistor being coupled to the corresponding external circuit to receive the clock signal, and the drain of the first transistor being configured for providing the second output signal.

3. The shift register in claim 2, wherein the second inversion circuit comprises a third transistor, a fourth transistor, a fifth transistor, and a sixth transistor, the source of the third transistor being coupled to the low level voltage, the drain of the third transistor being coupled to the source of the fourth transistor, the gate of the fourth transistor being coupled to the low level voltage, the source of the sixth transistor being coupled to the high level voltage and being coupled to the source of the fourth transistor via the drain of the sixth transistor and the source and the drain of the fifth transistor, the gate of the fifth transistor being coupled to the drain of the first transistor, and the gate of the third transistor being coupled to the previous adjacent shift register unit to receive the first output signal therefrom, except in the case of the first shift register unit wherein the gate of the third transistor is coupled to the corresponding external circuit.

4. The shift register in claim 3, wherein the third inversion circuit comprises a seventh transistor, an eighth transistor, a ninth transistor, and a tenth transistor, the source of the seventh transistor being coupled to the corresponding external circuit to receive the inverse clock signal and being coupled to the high level voltage via the drain of the seventh transistor and the source and the drain of the ninth transistor, the source of the eighth transistor being coupled to the corresponding external circuit to receive the inverse clock signal and being coupled to the high level voltage via the drain of the eighth transistor and the source and the drain of the tenth transistor, the gates of the seventh and eighth transistors being coupled to the drain of the fourth transistor, the gates of the ninth and tenth transistors being coupled to the gate of the fifth transistor, the drain of the seventh transistor being configured for providing the first output signal, the drain of the eighth transistor being configured for providing the shift register signal.

5. The shift register in claim 4, wherein the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth transistors are P-channel metal oxide semiconductor transistors.

6. The shift register in claim 1, wherein a duty ratio of the clock signal is equal to 50%.

7. The shift register in claim 1, wherein the start signal is a low level signal.

8. A shift register for providing a plurality of low level shift register signals, the shift register comprising a plurality of shift register units connected in series, each shift register unit comprising a first inversion circuit, a second inversion circuit, and a third inversion circuit;

the first inversion circuit comprising a first transistor and a second transistor, a source of the first transistor being coupled to a high level voltage, a drain of the first transistor being coupled to a drain of the second transistor, a source of the second transistor being coupled to a low level voltage, a gate of the first transistor being coupled to the third inversion circuit, and a gate of the second transistor being coupled to a clock signal source;

the second inversion circuit comprising a third transistor, a fourth transistor, a fifth transistor, and a sixth transistor, a source of the third transistor being coupled to the low level voltage, a drain of the third transistor being coupled to a source of the fourth transistor, a gate of the fourth transistor being coupled to the low level voltage, a source of the sixth transistor being coupled to the high level voltage and being coupled to the source of the fourth transistor via a drain of the sixth transistor, a gate of the fifth transistor being coupled to the drain of the first transistor, a drain of the fifth transistor being coupled to a first output of a previous adjacent one of the shift register units, except in the case of a first one of the shift register units, wherein the drain of the fifth transistor coupled to an external circuit;

the third inversion circuit comprising a seventh transistor and an eighth transistor, a source of the seventh transistor being coupled to an inverse clock signal source and being coupled to the high level voltage via a drain of the seventh transistor and a source and a drain of the eighth transistor, a gate of the seventh transistor being coupled to the drain of the fourth transistor, a gate of the eighth transistor being coupled to the gate of the fifth transistor;

wherein the two first inversion circuits of two adjacent shift register units receive the clock signal and the inverse clock signal, and the two third inversion circuits of the two adjacent shift register units receive the clock signal and the inverse clock signal, and the first shift register unit receives a start signal from the external circuit to start the shift register.

9. The shift register in claim 8, wherein the third inversion circuit further comprises a ninth transistor and a tenth transistor, the source of the ninth transistor being coupled to the inverse clock signal source and being coupled to the high level voltage via the drain of the ninth transistor and the source and the drain of the tenth transistor, the gate of the ninth transistor being coupled to the gate of the seventh transistor, and the gate of the tenth transistor being coupled to the gate of the eighth transistor.

10. The shift register in claim 8, wherein the start signal is a low level signal.

11. The shift register in claim 8, wherein a duty ratio of the clock signal is 50%.

12. The shift register in claim 9, wherein the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth transistors are P-channel metal oxide semiconductor transistors.

13. A liquid crystal display comprising:

a liquid crystal panel;

a gate driving circuit; and

a data driving circuit;

each of the gate driving circuit and the data driving circuit comprising at least one shift register, each of the shift registers comprising a plurality of shift register units, each shift register unit comprising a first inversion circuit, a second inversion circuit, and a third inversion circuit;

the first inversion circuit being configured for providing a second output signal according to a clock signal from an external circuit and a first output signal from the third inversion circuit;

the second inversion circuit being configured for providing a control signal according to a first output signal from a previous adjacent one of the shift register units and a second output signal from the previous adjacent shift register unit, except in the case of a first one of the shift register units, wherein the second inversion circuit is configured for providing a control signal according to a first external output signal from an external circuit and a second external output signal from an external circuit;

the third inversion circuit being configured for providing the first output signal and a shift register signal according to the control signal, the second output signal and an inverse clock signal from the external circuit;

wherein the two first inversion circuits of adjacent shift register units respectively receive the clock signal and the inverse clock signal, the two third inversion circuits of adjacent shift register units respectively receive the clock signal and the inverse clock signal, and the first shift register unit receives a start signal from an external circuit to start the shift register.

14. The liquid crystal display in claim 13, wherein all the transistors in the shift register are P-channel metal oxide semiconductor transistors.

15. The liquid crystal display in claim 13, wherein a duty ratio of the clock signal is equal to 50%.

16. The liquid crystal display in claim 13, wherein the start signal is a low level signal.