Liquid crystal display having electrodes with apertures wherein the apertures have different shapes

• US 6,342,938 B1
• Filed: 05/19/1999
• Issued: 01/29/2002
• Est. Priority Date: 05/19/1998
• Status: Expired due to Term

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Song, Jang-Kun, Kim, Kyeong-Hyeon, Lee, Hea-Ri, Lee, Kye-Hun
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Chowdhury, Tarifur R.
• Application Number:
  US09/314,293
• Time in Patent Office: 986 Days
• Field of Search: 349/143, 349/139, 349/86, 349/129, 349/130
• US Class Current: 349/143
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• 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
• CPC Class Codes: G02F 1/133753 with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
• CPC Class Codes: G02F 1/133757 with different alignment orientations
• CPC Class Codes: G02F 1/1343 Electrodes reflective electrodes G02F1/133553
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/13712 the liquid crystal having negative dielectric anisotropy
• 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 1/1396 the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell G02F1/141 takes precedence
• CPC Class Codes: G02F 2201/121 common or background

Abstract

A tetragonal ring shape aperture is formed in the common electrode on one substrate and a cross shape aperture is formed at the position corresponding to the center of the tetragonal ring shape aperture in the pixel electrode on the other substrate. A liquid crystal layer between two electrodes are divided to four domains where the directors of the liquid crystal layer have different angles when a voltage is applied to the electrodes. The directors in adjacent domains make a right angle. The tetragonal ring shape aperture is broken at midpoint of each side of the tetragon, and the width of the aperture decreases as goes from the bent point to the edge. Wide viewing angle is obtained by four domains where the directors of the liquid crystal layer indicate different directions, disclination is removed and luminance increases.

Claims

1. A liquid crystal display, comprising:

a first substrate having an inner surface and an outer surface;

a first electrode on the inner surface of said first substrate having a plurality of first apertures;

a second substrate having an inner surface and an outer surface; and

a second electrode on the inner surface of said second substrate having a plurality of second apertures and located at a position corresponding to the first electrode,

wherein boundaries of each of first aperture and each of the second aperture are bent at an obtuse angle and

wherein a respective width of the first aperture and the second aperture tapers from a respective center of the first aperture and the second aperture to a respective end of the first aperture and the second aperture.

2. The liquid crystal display of claim 1, wherein the first aperture is symmetric in shape and the second aperture is symmetric in shape.

3. The liquid crystal display of claim 1, wherein the first aperture and the second aperture form a substantially closed area shaped as polygon having at least four sides.

4. The liquid crystal display of claim 3, wherein the substantially closed area formed by the first aperture and the second aperture is symmetric in shape.

5. The liquid crystal display of claim 3, wherein the respective width of the first aperture and the second aperture is 3-20 μ

m.

6. The liquid crystal display of claim 3, wherein a distance between the first aperture and the second aperture is 5-20 μ

m.

7. The liquid crystal display of claim 1, wherein the respective width of the first aperture and the second aperture gradually decreases from 20 μ

m to 3 μ

m.

8. The liquid crystal display of claim 1, further comprising:

a liquid crystal layer interposed between said first substrate and said second substrate and having a negative dielectric anisotropy;

a first alignment layer on said first electrode;

a second alignment layer on said second electrode;

a first polarizer on the outer surface of said first substrate; and

a second polarizer on the outer surfaces of said second substrate,

wherein said first alignment layer and said second alignment layer respectively align the long axes of liquid crystal molecules in said liquid crystal layer to be perpendicular to said first substrate and said second substrate.

9. The liquid crystal display of claim 8, wherein a polarizing direction of said first polarizer is perpendicular to a polarizing direction of said second polarizer.

10. The liquid crystal display of claim 9, wherein the number of average axial directions of liquid crystal molecules in domains defined by the first aperture and the second aperture is four.

11. The liquid crystal display of claim 10, wherein the average axial directions of liquid crystal molecules are at an angle of 45°

±

10°

with the polarizing directions of said first polarizer and said second polarizer.

12. The liquid crystal display of claim 11, wherein the average axial directions of liquid crystal molecules in the domain cross at a substantially right angle.

13. The liquid crystal display of claim 1, wherein the boundaries of the first aperture and the second aperture are bent at least twice per each domain defined by the first aperture and the second aperture.

14. The liquid crystal display of claim 1, wherein the first aperture and the second aperture form an area that is diametrically symmetric.

15. The liquid crystal display of claim 14, wherein a half of the diametrically symmetric area is trapezoidal in shape.

16. The liquid crystal display of claim 1, further comprising:

a first polarizer attached on the outer surface of said first substrate; and

a compensation film interposed between said first substrate and said first polarizer,

wherein said compensation film is uniaxial or biaxial.

17. The liquid crystal display of claims 16, wherein said compensation film is biaxial, and one of slow axes of said compensation film is substantially parallel to a transmission axis of said first polarizer.

18. A liquid crystal display, comprising:

a first substrate having an inner surface and an outer surface;

a first electrode on the inner surface of said first substrate having a plurality of first apertures;

a second substrate having an inner surface and an outer surface; and

a second electrode on the inner surface of said second substrate having a plurality of second apertures and located at a position corresponding to said first electrode,

wherein the first aperture an the second aperture form a substantially closed area, which has a polygonal shape with at least four sides, and

wherein a respective width of the first aperture and the second aperture tapers from a respective center of the first aperture and the second aperture to a respective end of the first aperture and the second aperture.

19. The liquid crystal display of claim 18, wherein the respective width of the first aperture and the second aperture is 3-20 μ

m.

20. The liquid crystal display of claim 18, wherein the respective width of the first aperture and the second aperture gradually decreases from 20 μ

m to 3 μ

m.