Vertical alignment active matrix liquid crystal display device

• US 20060066791A1
• Filed: 09/28/2005
• Published: 03/30/2006
• Est. Priority Date: 09/30/2004
• Status: Abandoned Application

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Yamaguchi, Minoru, Mizusako, Ryota, Nakajima, Yasushi
• Application Number:
  US11/238,027
• Publication Number:
  US 20060066791A1
• Time in Patent Office: Days
• US Class Current: 349/123
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• 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 1/133742 for homeotropic alignment

Abstract

A liquid crystal display device comprises a TFT substrate where TFTs are formed, an opposing substrate (CF substrate), a liquid crystal with a negative dielectric anisotropy filled between both substrates, a pixel electrode, and an auxiliary electrode formed around the pixel electrode. The pixel electrode has a recess portion formed by etching a gate insulation film. The liquid crystal molecules are aligned tilted toward the center of a pixel according to the shape of the recess portion.

Claims

1. A liquid crystal display device comprising:

a first substrate provided with a first electrode;

a second substrate which is provided with at least one second electrode arranged opposite to the first electrode with a predetermined gap therebetween, and forming individual pixel regions with that region which faces the first electrode;

an auxiliary electrode formed on that surface of the second substrate on which the second electrode is provided, along at least a periphery of the pixel region;

a vertical alignment film formed on each of opposing inner surfaces of the first electrode and the second electrode;

a liquid crystal layer with a negative dielectric anisotropy filled between the first and second substrates;

at least one of a recess portion and a projecting portion, which is formed on at least one of the first and second electrodes, at a position corresponding to substantially a center of the pixel region, for aligning liquid crystal molecules of the liquid crystal layer according to a shape of the at least one of the recess portion and the projecting portion.

2. The liquid crystal display device according to claim 1, wherein the recess portion is formed at substantially a center of the second electrode.

3. The liquid crystal display device according to claim 1, wherein the projecting portion is formed at a position corresponding to the center of the pixel region of the first electrode.

4. The liquid crystal display device according to claim 3, wherein the projecting portion formed at the position corresponding to the center of the pixel region of the first electrode is a projection made of an insulating material formed on the first electrode.

5. The liquid crystal display device according to claim 3, wherein a projection comprising a light shielding film is formed at that portion of the first substrate which corresponds to the projecting portion formed at the position corresponding to the center of the pixel region of the first electrode.

6. The liquid crystal display device according to claim 3, wherein a color filter corresponding to each pixel region, and a black mask of a light-shielding resin are formed on the first substrate for each pixel region, the black mask being located at a position where the black mask covers around each pixel region, and

the projecting portion formed at the position corresponding to the center of the pixel region of the first electrode is formed by a projection of a resin for forming the black mask formed between the first substrate and the color filter.

7. The liquid crystal display device according to claim 1, wherein a peripheral projecting portion extending along a peripheral portion of the pixel region is further formed on the second substrate.

8. The liquid crystal display device according to claim 7, wherein the peripheral projecting portion formed on the second substrate comprises an insulation film formed in such a way that an edge of the insulation film overlies a part of the auxiliary electrode.

9. A liquid crystal display device comprising:

a first substrate provided with a first electrode;

a second substrate which is provided with at least one second electrode arranged opposite to the first electrode with a predetermined gap therebetween, and forming individual pixel regions with that region which faces the first electrode;

an auxiliary electrode formed on that surface of the second substrate on which the second electrode is provided, along at least a periphery of the pixel region;

a vertical alignment film formed on each of opposing inner surfaces of the first electrode and the second electrode;

a liquid crystal layer with a negative dielectric anisotropy filled between the first and second substrates;

at least one of a recess portion and a projecting portion, which is formed on at least one of the first and second electrodes, at a position corresponding to substantially a center of the pixel region, for defining a center position of alignment of liquid crystal molecules to be aligned spirally toward a center from a peripheral portion by an electric field to be applied between the second electrode and the auxiliary electrode.

10. The liquid crystal display device according to claim 9, wherein the recess portion is formed on the second electrode of the second substrate.

11. The liquid crystal display device according to claim 9, wherein the recess portion is formed at a center of the second electrode of the second substrate, and a peripheral projecting portion extending formed along a peripheral portion of the pixel region is further provided on the second substrate.

12. The liquid crystal display device according to claim 9, wherein the projecting portion is formed at a position corresponding to the center of the pixel region of the first electrode.

13. The liquid crystal display device according to claim 9, wherein the projecting portion is provided on the first substrate at a position corresponding to the center of the pixel region, and

a peripheral projecting portion extending along a peripheral portion of the pixel region is further formed on the second substrate.

14. The liquid crystal display device according to claim 9, wherein a color filter corresponding to the pixel region is formed on that surface of the first substrate which faces the second substrate, and

the projecting portion formed on the first electrode comprises a projection provided at the color filter.

15. The liquid crystal display device according to claim 9, wherein the auxiliary electrode is set to a potential lower than that of the second electrode.

16. The liquid crystal display device according to claim 9, wherein the auxiliary electrode comprises a compensating-capacitor electrode which overlies a peripheral portion of the second electrode and forms a compensating capacitor between the compensating-capacitor electrode and the second electrode.

17. The liquid crystal display device according to claim 9, wherein a projecting portion comprising an insulation film and a metal film for shielding light transmitting a center of the projecting portion are formed on an inner surface of the first substrate at a position corresponding to the center of the pixel region.

18. The liquid crystal display device according to claim 9, wherein the projecting portion comprises a spacer for adjusting a gap between the first electrode and the second electrode.

19. A liquid crystal display device comprising:

a first substrate provided with a first electrode;

a second substrate which is provided with at least one second electrode arranged opposite to the first electrode with a predetermined gap therebetween, and forming individual pixel regions with that region which faces the first electrode;

an auxiliary electrode formed on that surface of the second substrate on which the second electrode is provided, along at least a periphery of the pixel region;

a vertical alignment film formed on each of opposing inner surfaces of the first electrode and the second electrode; and

a liquid crystal layer with a negative dielectric anisotropy filled between the first and second substrates,

wherein at least one of the first and second electrodes is formed inclined toward a peripheral portion of the pixel region from a center thereof in such a way that molecular long axes of liquid crystal molecules of the liquid crystal layer are aligned tilted toward the center of the pixel region.

20. The liquid crystal display device according to claim 19, wherein a color filter having a cross section formed in such a way that a center portion is thicker than a peripheral portion is provided on that surface of the second substrate which faces the first substrate.