Active matrix type liquid-crystal display unit and method of driving the same

• US 6,456,269 B2
• Filed: 05/03/2001
• Issued: 09/24/2002
• Est. Priority Date: 11/07/1995
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hirakata, Yoshiharu
• Primary Examiner(s): LAO, LUN YI
• Application Number:
  US09/848,890
• Publication Number:
  US 20010015710A1
• Time in Patent Office: 509 Days
• Field of Search: 345/87, 345/92, 345/93-96, 345/204, 345/103, 345/208, 345/209, 345/210, 349/41-42, 349/47-48
• US Class Current: 345/92
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0823 used to establish symmetry in driving, e.g. with polarity inversion
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes

Abstract

A data signal having a single polarity is outputted from a data driver of an in-plane switching type liquid-crystal display unit. In a unit pixel, an input transistor and an exhaust transistor T2 are connected to one electrode of a liquid-crystal element LC, and an input transistor and an exhaust transistor are connected to the other electrode. One input transistor and one exhaust transistor connected to the same scanning line are paired, and another input transistor and another exhaust transistor connected to another same scanning line are paired. Those paired transistors are alternately driven, thereby being capable of inverting the potential between electrodes of the liquid-crystal element even when the polarity of the data signal is single.

Claims

1. A display device comprising:

a pair of substrates;

a liquid crystal provided between said substrates;

a pixel having a pair of first and second electrodes holding said liquid crystal therebetween,

a first thin film transistor provided in said pixel and connected to said first electrode at one of source region and drain region thereof;

a second thin film transistor provided in said pixel and connected to said second electrode at one of source region and drain region thereof;

an image write signal line connected to the other of the source region and the drain region of said first thin film transistor;

a reference potential line connected to the other of the source region and the drain region of said second thin film transistor;

a gate line connected to a gate electrode of said first thin film transistor and connected to a gate electrode of said second thin film transistor,

wherein a voltage having single polarity is applied between said first and second electrodes by applying an image write signal to said first electrode and setting said second electrode to a reference potential, and

wherein said first and second electrodes are provided over one of said substrates to effect the application of said voltage in a in-plane switching mode.

2. A device according to claim 1 wherein said first and second thin film transistors are n-type thin film transistors.

3. A device according to claim 1 wherein said first and second thin film transistors are p-type thin film transistors.

4. A device according to claim 1 wherein said liquid crystal comprises a TN liquid crystal.

5. A display device comprising:

a pair of substrates;

a scanning driver provided over one of said substrates;

a data driver provided over said one of said substrates;

a liquid crystal provided between said substrates;

a pixel having a pair of first and second electrodes holding said liquid crystal therebetween,

a first thin film transistor provided in said pixel and connected to said first electrode at one of source region and drain region thereof;

a second thin film transistor provided in said pixel and connected to said second electrode at one of source region and drain region thereof;

an image write signal line connected to the other of the source region and the drain region of said first thin film transistor;

a reference potential line connected to the other of the source region and the drain region of said second thin film transistor;

a gate line connected to a gate electrode of said first thin film transistor and connected to a gate electrode of said second thin film transistor,

wherein a voltage having single polarity is applied between said first and second electrodes by applying an image write signal to said first electrode and setting said second electrode to a reference potential, and

wherein said first and second electrodes are provided over said one of said substrates to effect the application of said voltage in a in-plane switching mode.

6. A device according to claim 5 wherein said data driver is connected with said image write signal line.

7. A device according to claim 5 wherein said scanning driver is connected with said gate line.

8. A device according to claim 5 wherein said scanning driver and said data driver are provided over said one of said substrates monolithically with said first and second thin film transistors.

9. A device according to claim 5 wherein said first and second thin film transistors are n-type thin film transistors.

10. A device according to claim 5 wherein said first and second thin film transistors are p-type thin film transistors.

11. A device according to claim 5 wherein said liquid crystal comprises a TN liquid crystal.

12. A display device comprising:

a pair of substrates;

a liquid crystal provided between said substrates;

a pixel having a pair of first and second electrodes holding said liquid crystal therebetween,

a first thin film transistor provided in said pixel and connected to said first electrode at one of source region and drain region thereof;

a second thin film transistor provided in said pixel and connected to said second electrode at one of source region and drain region thereof;

an image write signal line connected to the other of the source region and the drain region of said first thin film transistor;

a reference potential line connected to the other of the source region and the drain region of said second thin film transistor;

a gate line connected to a gate electrode of said first th in film transistor and connected to a gate electrode of said second thin film transistor,

wherein a voltage having single polarity is applied between said first and second electrodes by applying an image write signal to said first electrode and setting said second electrode to a reference potential,

wherein said first and second electrodes are provided over one of said substrates to effect the application of said voltage in a in-plane switching mode, and

wherein a potential level of said image write signal is always of a single polarity.

13. A device according to claim 12 wherein said first and second thin film transistors are n-type thin film transistors.

14. A device according to claim 12 wherein said first and second thin film transistors are p-type thin film transistors.

15. A device according to claim 12 wherein said liquid crystal comprises a TN liquid crystal.

16. A display device comprising:

a pair of substrates;

a scanning driver provided over one of said substrates;

a data driver provided over said one of said substrates;

a liquid crystal provided between said substrates;

a pixel having a pair of first and second electrodes holding said liquid crystal therebetween,

a first thin film transistor provided in said pixel and connected to said first electrode at one of source region and drain region thereof;

a second thin film transistor provided in said pixel and connected to said second electrode at one of source region and drain region thereof;

an image write signal line connected to the other of the source region and the drain region of said first thin film transistor;

a reference potential line connected to the other of the source region and the drain region of said second thin film transistor;

a gate line connected to a gate electrode of said first thin film transistor and connected to a gate electrode of said second thin film transistor,

wherein a voltage having single polarity is applied between said first and second electrodes by applying an image write signal to said first electrode and setting said second electrode to a reference potential,

wherein said first and second electrodes are provided over said one of said substrates to effect the application of said voltage in a in-plane switching mode, and

wherein a potential level of said image write signal is always of a single polarity.

17. A device according to claim 16 wherein said data driver is connected with said image write signal line.

18. A device according to claim 16 wherein said scanning driver is connected with said gate line.

19. A device according to claim 16 wherein said scanning driver and said data driver are provided over said one of said substrates monolithically with said first and second thin film transistors.

20. A device according to claim 16 wherein said first and second thin film transistors are n-type thin film transistors.

21. A device according to claim 16 wherein said first and second thin film transistors are p-type thin film transistors.

22. A device according to claim 16 wherein said liquid crystal comprises a TN liquid crystal.