Vertical alignment active matrix liquid crystal display device

• US 20060114405A1
• Filed: 11/29/2005
• Published: 06/01/2006
• Est. Priority Date: 11/29/2004
• Status: Abandoned Application

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Yamaguchi, Minoru, Mizusako, Ryota, Nishino, Toshiharu
• Application Number:
  US11/288,522
• Publication Number:
  US 20060114405A1
• Time in Patent Office: Days
• US Class Current: 349/178
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G02F 2202/42 Materials having a particular dielectric constant

Abstract

A vertical-alignment liquid crystal display device is constituted by a first substrate on which a first electrode is formed, a second substrate on which a second electrode opposed to the first electrode is formed and which is opposed to the first substrate, alignment films respectively on mutually opposing inner surfaces of the first and second substrates, and a liquid crystal layer sealed between the first and second substrates and having negative dielectric anisotropy. On the second electrode, dielectric films having a dielectric constant different from another dielectric constant of the liquid crystal layer in the layer thickness direction of the liquid crystal layer when a voltage is applied between the first and second electrodes are provided at positions respectively corresponding to the center portions of plural pixels.

Claims

1. A liquid crystal display device comprising:

a pair of substrates opposed to each other with a predetermined gap maintained therebetween;

electrodes provided respectively on mutually opposing inner surfaces of the pair of substrates, and defining plural pixels by mutually opposing regions, the plural pixels being arrayed in a matrix;

dielectric films provided respectively corresponding to substantial center portions of regions of one of the substrates, the regions corresponding to the plural pixels;

vertical-alignment films provided respectively on the inner surfaces of the paired substrates, covering the electrodes and the dielectric films; and

a liquid crystal layer having negative dielectric anisotropy and sealed in the gap between the pair of substrates.

2. The liquid crystal display device according to claim 1, wherein the dielectric film is formed at the substantial center of each pixel formed on one of the substrates, and has a dielectric constant different from another dielectric constant of the liquid crystal layer in a layer thickness direction of the liquid crystal layer when a voltage is applied between electrodes of the pair of substrates.

3. The liquid crystal display device according to claim 2, wherein the dielectric films are formed of a dielectric material having a smaller dielectric constant than the another dielectric constant of the liquid crystal layer in the layer thickness direction thereof when the voltage is applied between the electrodes.

4. The liquid crystal display device according to claim 2, wherein the dielectric films are formed of a dielectric material having a dielectric constant which is smaller than further another dielectric constant of liquid crystal in a direction vertical to major axes of molecules of the liquid crystal.

5. The liquid crystal display device according to claim 2, wherein the dielectric films are formed of a dielectric material having a dielectric constant which is smaller than further another dielectric constant of liquid crystal in a direction perpendicular to major axes of molecules of the liquid crystal and is greater than still further another dielectric constant of the liquid crystal in a direction parallel to the major axes of molecules of the liquid crystal.

6. The liquid crystal display device according to claim 2, further comprising auxiliary electrodes formed at least along peripheries of the pixels are provided on a surface of one of the substrates opposed to the other substrate, the surface being provided with the electrode.

7. The liquid crystal display device according to claim 6, wherein the auxiliary electrode is set to a lower potential than the electrode formed on the other one of the substrates.

8. The liquid crystal display device according to claim 6, wherein the auxiliary electrodes are provided, partially overlapping peripheral portions of the electrodes formed on the one of the substrates.

9. The liquid crystal display device according to claim 1, wherein the dielectric films form projecting parts at the substantial centers of the pixels respectively, the projecting parts include the electrodes formed on the dielectric films and a vertical-alignment film formed on the electrodes.

10. The liquid crystal display device according to claim 9, further comprising a plurality of recess parts provided on the inner surface of the other substrate opposed to the one of the substrates on which the projecting parts are formed, the recess parts corresponding to the plurality of aid projecting parts provided on the inner surface of the one of the substrates.

11. A liquid crystal display device comprising:

a first substrate on which at least one electrode is provided;

a second substrate which is opposed to the first substrate with a predetermined gap maintained from the first substrate, and on which at least one second electrode is provided, each of the at least one the second electrode defining a pixel by a region opposed to the first electrode, to array the plural pixels in a matrix;

auxiliary electrodes formed at least along peripheries of regions of the pixels, on a surface of the second substrate where the second electrode is provided;

dielectric films which are provided respectively corresponding to substantial center portions of pixels of the first substrate and have a dielectric constant different from another dielectric constant of a liquid crystal layer in a layer thickness direction when a voltage is applied between the first and second electrodes;

vertical-alignment films provided respectively on mutually opposing inner surfaces of the first and second substrates, covering the first and second electrodes and the dielectric films; and

the liquid crystal layer sealed between the first and second substrates and having negative dielectric anisotropy.

12. The liquid crystal display device according to claim 11, wherein the dielectric films are formed on the first electrode provided on the first substrate, and the vertical-alignment film is formed on the dielectric films.

13. The liquid crystal display device according to claim 11, wherein the dielectric films are formed of a dielectric material having a smaller dielectric constant than another dielectric constant of the liquid crystal layer in a layer thickness direction thereof when a voltage is applied between the electrodes.

14. The liquid crystal display device according to claim 11, wherein the dielectric films are formed of a dielectric material having a dielectric constant which is smaller than another dielectric constant of liquid crystal in a direction vertical to major axes of molecules of the liquid crystal.

15. The liquid crystal display device according to claim 11, wherein the dielectric films are formed of a dielectric material having a dielectric constant which is smaller than another dielectric constant of liquid crystal in a direction vertical to major axes of molecules of the liquid crystal and is greater than still another dielectric constant of the liquid crystal in a direction parallel to the major axes of molecules of the liquid crystal.

16. The liquid crystal display device according to claim 11, wherein the auxiliary electrodes are formed substantially throughout the whole peripheries of the second electrode.

17. The liquid crystal display device according to claim 11, wherein an active element connected to each of the at least one second electrode to supply the second electrode with a voltage is provided on the second substrate, and

the auxiliary electrodes each are constituted by a compensating-capacitor electrode which is provided partly overlapping a peripheral portion of the second electrode formed on the second substrate, to form a compensating capacitor between the second electrode and the auxiliary electrode.

18. The liquid crystal display device according to claim 17, wherein the compensation auxiliary electrode is set to a potential equal to that of the first electrode.

19. A liquid crystal display device comprising:

a first substrate on which at least one electrode is provided;

a second substrate which is opposed to the first substrate with a predetermined gap maintained from the first substrate, and on which at least one second electrode is provided, each of the at least one the second electrode forming a pixel by a region opposed to the first electrode, to array the plural pixels in a matrix;

auxiliary electrode formed at least along peripheries of regions of the pixels, on a surface of the second substrate where the second electrode is provided;

dielectric films which are formed between the first electrode and the first substrate, respectively corresponding to substantial center portions of regions of the first substrate, the regions corresponding to the plural pixels, thereby to form convex portions on a surface of the first electrode;

vertical-alignment films provided respectively on mutually opposing inner surfaces of the first and second substrates, covering the first and second electrodes; and

the liquid crystal layer sealed between the first and second substrates and having negative dielectric anisotropy.

20. The liquid crystal display device according to claim 19, wherein plural concave parts are provided at positions on the second substrate opposed to the first substrate on which the convex parts are formed, the positions respectively corresponding to the plural convex parts.