Liquid crystal display device

• US 20050046763A1
• Filed: 07/19/2004
• Published: 03/03/2005
• Est. Priority Date: 08/29/2003
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Ono, Kikuo, Oke, Ryutaro
• Granted Patent: US 7,256,852 B2
• Time in Patent Office: Days
• US Class Current: 349/39
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel

Abstract

A liquid crystal display device includes a first electrode to which a signal is supplied through a first switching element and a second electrode to which a signal is supplied through a second switching element in each pixel region on a substrate, wherein liquid crystal is driven in response to a potential difference between the first electrode and the second electrode. In such a constitution, the first electrode is formed as one electrode of a first holding capacitance which is constituted by sandwiching an insulation film between the first electrode and a signal line and, at the same time, the second electrode is formed as one electrode of a second holding capacitance which is constituted by sandwiching an insulation film between the second electrode and a signal line.

Claims

1. A liquid crystal display device comprising:

a first electrode to which a signal is supplied through a first switching element and a second electrode to which a signal is supplied through a second switching element in each pixel region on a substrate, wherein liquid crystal is driven in response to a potential difference between the first electrode and the second electrode, wherein

the first electrode is formed as one electrode of a first holding capacitance which is constituted by sandwiching an insulation film between the first electrode and a signal line, and the second electrode is formed as one electrode of a second holding capacitance which is constituted by sandwiching an insulation film between the second electrode and a signal line.

2. A liquid crystal display device according to claim 1, wherein the first electrode and the second electrode are formed of a light transmitting conductive film, the first electrode and the second electrode are formed as different layers by way of an insulation film, one electrode is formed on a most portion of the pixel region, and another electrode is formed of a group of electrodes which are overlapped to one electrode.

3. A liquid crystal display device according to claim 1, wherein a signal line which constitutes another electrode of the first holding capacitance is a first drain signal line, and a signal line which constitutes another electrode of the second holding capacitance is a second drain signal line.

4. A liquid crystal display device according to claim 1, wherein a signal line which constitutes another electrode of the first holding capacitance and a signal line which constitutes another electrode of the second holding capacitance are formed of a capacitance signal line.

5. A liquid crystal display device according to claim 4, wherein a capacitance value of the first holding capacitance is substantially equal to a capacitance value of the second holding capacitance.

6. A liquid crystal display device according to claim 5, wherein the first electrode and the second electrode are formed of a light transmitting conductive film, the first electrode and the second electrode are formed as different layers by way of an insulation film, one electrode is formed on a most portion of the pixel region, and another electrode is formed of a group of electrodes which are overlapped to one electrode.

7. A liquid crystal display device comprising:

a first electrode to which a signal is supplied from a first drain signal line through a first switching element and a second electrode to which a signal is supplied from a second drain signal line through a second switching element in each pixel region on a substrate, wherein liquid crystal is driven in response to a potential difference between the first electrode and the second electrode, wherein

the first electrode and the second electrode are formed on different layers by way of an insulation film with respect to the first drain signal line and the second drain signal line,

and portions of the first electrode and the second electrode are overlapped to the first drain signal line and the second drain signal line.

8. A liquid crystal display device according to claim 7, wherein the first electrode has portions thereof overlapped to the first drain signal line and the second drain signal line respectively, and the second electrode has portions thereof overlapped to the first drain signal line and the second drain signal line respectively.

9. A liquid crystal display device according to claim 8, wherein the portions of the first electrode which are overlapped to the first drain signal line and the portions of the second electrode which are overlapped to the first drain signal line are substantially at the same positions, and the portions of the first electrode which are overlapped to the second drain signal line and the portions of the second electrode which are overlapped to the second drain signal line are substantially at the same positions.

10. A liquid crystal display device according to claim 8, wherein the portions of the first electrode which are overlapped to the first drain signal line, the portions of the second electrode which are overlapped to the first drain signal line, the portions of the first electrode which are overlapped to the second drain signal line, and the portions of the second electrode which are overlapped to the second drain signal line respectively constitute holding capacitances.

11. A liquid crystal display device according to claim 8, wherein values of respective holding capacitances formed by the portions of the first electrode which are overlapped to the first drain signal line, the portions of the second electrode which are overlapped to the first drain signal line, the portions of the first electrode which are overlapped to the second drain signal line, and the portions of the second electrode which are overlapped to the second drain signal line fall all together within a scope of 50% to 200%.

12. A liquid crystal display device according to claim 11, wherein the capacitance value of the holding capacitance of the portions of the first electrode which are overlapped to the first drain signal line and the capacitance value of the holding capacitance of the portions of the first electrode which are overlapped to the second drain signal line are substantially equal and, at the same time, the capacitance value of the holding capacitance of the portions of the second electrode which are overlapped to the first drain signal line and the capacitance value of the holding capacitance of the portions of the second electrode which are overlapped to the second drain signal line are substantially equal.

13. A liquid crystal display device according to claim 8, wherein the portions of the first electrode which are overlapped to the first drain signal line and the portions of the second electrode which are overlapped to the first drain signal line as well as the portions of the first electrode which are overlapped to the second drain signal line and the portions of the second electrode which are overlapped to the second drain signal line are arranged in a staggered manner.

14. A liquid crystal display device comprising:

a first electrode to which a signal is supplied from a first drain signal line through a first switching element and a second electrode to which a signal is supplied from a second drain signal line through a second switching element in each pixel region on a substrate, wherein liquid crystal is driven in response to a potential difference between the first electrode and the second electrode, wherein

the liquid crystal display device includes holding capacitance signal lines,

the holding capacitance signal lines are overlapped to a plurality portions of the first electrodes by way of a first insulation film, and

the holding capacitance signal lines are overlapped to the second electrodes at regions between a plurality portions of the first electrodes by way of a first insulation film and a second insulation film.

15. A liquid crystal display device according to claim 14, wherein with respect to overlapped areas where the holding capacitance signal line is overlapped with the first electrode and the second electrode, the overlapped area where the holding capacitance signal line is overlapped with the second electrode is larger than the overlapped area where the holding capacitance signal line is overlapped with the first electrode.

16. A liquid crystal display device according to claim 14, wherein the holding capacitance formed by the holding capacitance signal line and the first electrode and the holding capacitance formed by the holding capacitance signal line and the second electrode are substantially equal.

17. A liquid crystal display device according to claim 14, wherein the first electrode and the second electrode are formed of a light transmitting conductive film, the first electrode and the second electrode are formed as different layers by way of an insulation film, one electrode is formed on a most region of the pixel region, and another electrode is formed of a group of electrodes which are overlapped to one electrode.