Liquid crystal display device

• US 6,734,924 B2
• Filed: 09/07/2001
• Issued: 05/11/2004
• Est. Priority Date: 09/08/2000
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hirakata, Yoshiharu, Satake, Rumo, Hamamoto, Yuriko
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): STEVENSON, ANDRE C
• Application Number:
  US09/949,415
• Publication Number:
  US 20020063841A1
• Time in Patent Office: 977 Days
• Field of Search: 349/39, 349/43, 349/46, 349/141, 257/79
• US Class Current: 349/39
• CPC Class Codes: G02F 1/1333 Constructional arrangements; Manufacturing methodsG02F1/135, G02F1/136 take precedence
• 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 1/13373 Disclination line; Reverse tilt
• CPC Class Codes: G02F 1/133776 having structures locally influencing the alignment, e.g. unevenness
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element

Abstract

Disclination of an active matrix liquid crystal display device is reduced. Portions of pixel electrodes are formed so as to mutually overlap with a convex portion. If the height of the convex portion is too tall, the amount of light leakage increases due to liquid crystals orienting diagonally with respect to a substrate surface. (See FIG. 1C.) If the height of the convex portion is low, the disclination reduction effect is low. The optimal convex portion height is thus determined.

Claims

1. A liquid crystal display device comprising:

a convex portion selectively formed below a pixel electrode formed on a first substrate;

a first region of the pixel electrode formed overlapping with an upper edge portion of the convex portion;

a second region of the pixel electrode formed in a side portion of the convex portion; and

a third region of the pixel electrode contacting the second region of the pixel 4.5 μ

m electrode;

wherein;

the distance from an opposing electrode formed on a second substrate to the third region of the pixel electrode is greater than or equal to 3.0 μ

m, and less than or equal to 4.5 μ

m; and

the height of the convex portion is greater than or equal to 4.4% of the distance, and less than or equal to 15.6% of the distance.

14. A liquid crystal display device according to any one of claims 1 to 13, wherein the width over which the first region of the pixel electrode and the convex portion overlap is greater than or equal to 0.5 μ

m.

15. A liquid crystal display device according to any one of claims 1 to 13, wherein the width over which the first region of the pixel electrode and the convex portion overlap is greater than or equal to 1.0 μ

m.

16. A liquid crystal display device according to any one of claims 1 to 15, wherein the liquid crystal display device has the first regions of the mutually adjacent pixel electrodes in the upper edge portions of the convex portions, and the distance between the first regions of the pixel electrodes is less than or equal to 4.0 μ

m.

17. A liquid crystal display device according to any one of claims 1 to 15, wherein the liquid crystal display device has the first regions of the mutually adjacent pixel electrodes in the upper edge portions of the convex portions, and the distance between the first regions of the pixel electrodes is less than or equal to 2.0 μ

m.

2. A liquid crystal display device comprising:

a convex portion selectively formed below a pixel electrode formed on a first substrate;

a first region of the pixel electrode formed overlapping with an upper edge portion of the convex portion;

a second region of the pixel electrode formed in a side portion of the convex portion; and

a third region of the pixel electrode contacting the second region of the pixel electrode;

wherein;

the distance from an opposing electrode formed on a second substrate to the third region of the pixel electrode is less than or equal to 3.0 μ

m; and

the height of the convex portion is less than or equal to 15.6% of the distance.

3. A liquid crystal display device comprising:

a convex portion selectively formed below a pixel electrode formed on a first substrate;

a first region of the pixel electrode formed overlapping with an upper edge portion of the convex portion;

a second region of the pixel electrode formed in a side portion of the convex portion; and

a third region of the pixel electrode contacting the second region of the pixel electrode;

wherein;

the distance from an opposing electrode formed on a second substrate to the third region is less than or equal to 3.0 μ

m; and

the height of the convex portion is less than or equal to 6.7% of the distance.

4. A liquid crystal display device comprising:

a convex portion on a level surface in a first substrate;

a first region of a pixel electrode formed overlapping with an upper edge portion of the convex portion;

a second region of the pixel electrode formed in a side portion of the convex portion; and

a third region of the pixel electrode formed on the level surface;

wherein;

the distance from an opposing electrode formed on a second substrate to the third region of the pixel electrode is greater than or equal to 3.0 μ

m, and less than or equal to 4.5 μ

m; and

the height of the convex portion is greater than or equal to 4.4% of the distance, and less than or equal to 15.6% of the distance.

5. A liquid crystal display device comprising:

a convex portion on a level surface in a first substrate;

a first region of a pixel electrode formed overlapping with an upper edge portion of the convex portion;

a second region of the pixel electrode formed in a side portion of the convex portion; and

a third region of the pixel electrode formed on the level surface;

wherein;

the distance from an opposing electrode formed on a second substrate to the third region of the pixel electrode is less than or equal to 3.0 μ

m; and

the height of the convex portion is less than or equal to 15.6% of the distance.

6. A liquid crystal display device comprising:

a convex portion on a level surface in a first substrate;

a first region of a pixel electrode formed overlapping with an upper edge portion of the convex portion;

a second region of the pixel electrode formed in a side portion of the convex portion; and

a third region of the pixel electrode formed on the level surface;

wherein;

the distance from an opposing electrode formed on a second substrate to the third region of the pixel electrode is less than or equal to 3.0 μ

m; and

the height of the convex portion is less than or equal to 6.7% of the distance.

7. A liquid crystal display device comprising:

a convex portion having a first height, and a convex portion having a second height, selectively formed below a pixel electrode formed on a first substrate;

a first region of the pixel electrode formed overlapping an upper edge portion of the convex portion having the first height, and an upper edge portion of the convex portion having the second height, in the pixel electrode;

a second region of the pixel electrode formed in a side portion of the convex portion having the first height, and a side portion of the convex portion having the second height; and

a third region of the pixel electrode contacting the second region of the pixel electrode;

wherein;

the convex portion having the first height is relatively higher than the convex portion having the second height;

the distance from an opposing electrode formed on a second substrate to the third region of the pixel electrode is greater than or equal to 3.0 μ

m, and less than or equal to 4.5 μ

m; and

the height of the convex portion having the first height and the height of the convex portion having the second height are greater than or equal to 4.4% of the distance, and less than or equal to 15.6% of the distance.

8. A liquid crystal display device comprising:

a convex portion having a first height, and a convex portion having a second height, formed on a level surface on a first substrate;

a first region of a pixel electrode formed overlapping an upper edge portion of the convex portion having the first height, and an upper edge portion of the convex portion having the second height;

a second region of the pixel electrode formed in a side portion of the convex portion having the first height, and a side portion of the convex portion having the second height;

a third region of the pixel electrode formed on the level surface; and

an opposing electrode formed on a second substrate;

wherein;

the convex portion having the first height is relatively higher than the convex portion having the second height;

the distance from the opposing electrode formed on the second substrate to the third region of the pixel electrode is greater than or equal to 3.0 μ

m, and less than or equal to 4.5 μ

m; and

the height of the convex portion having the first height and the height of the convex portion having the second height are greater than or equal to 4.4% of the distance, and less than or equal to 15.6% of the distance.

9. A liquid crystal display device comprising:

a convex portion having a first height, and a convex portion having a second height, selectively formed below a pixel electrode formed on a first substrate;

a first region of the pixel electrode formed overlapping an upper edge portion of the convex portion having the first height, and an upper edge portion of the convex portion having the second height, in the pixel electrode;

a second region of the pixel electrode formed in a side portion of the convex portion having the first height, and a side portion of the convex portion having the second height; and

a third region of the pixel electrode contacting the second region of the pixel electrode;

wherein;

the convex portion having the first height is relatively higher than the convex portion having the second height;

the distance from an opposing electrode formed on a second substrate to the third region of the pixel electrode is less than or equal to 3.0 μ

m; and

the height of the convex portion having the first height and the height of the convex portion having the second height are less than or equal to 15.6% of the distance.

10. A liquid crystal display device comprising:

a convex portion having a first height, and a convex portion having a second height, formed on a level surface on a first substrate;

a first region of a pixel electrode formed overlapping an upper edge portion of the convex portion having the first height, and an upper edge portion of the convex portion having the second height;

a second region of the pixel electrode formed in a side portion of the convex portion having the first height, and a side portion of the convex portion having the second height;

a third region of the pixel electrode formed on the level surface; and

an opposing electrode formed on a second substrate;

wherein;

the convex portion having the first height is relatively higher than the convex portion having the second height;

the distance from the opposing electrode formed on the second substrate to the third region of the pixel electrode is less than or equal to 3.0 μ

m; and

the height of the convex portion having the first height and the height of the convex portion having the second height are less than or equal to 15.6% of the distance.

11. A liquid crystal display device comprising:

a convex portion having a first height, and a convex portion having a second height, selectively formed below a pixel electrode formed on a first substrate;

a first region of the pixel electrode formed overlapping an upper edge portion of the convex portion having the first height, and an upper edge portion of the convex portion having the second height, in the pixel electrode;

a second region of the pixel electrode formed in a side portion of the convex portion having the first height, and a side portion of the convex portion having the second height; and

a third region of the pixel electrode contacting the second region of the pixel electrode;

wherein;

the convex portion having the first height is relatively higher than the convex portion having the second height;

the distance from an opposing electrode formed on a second substrate to the third region of the pixel electrode is less than or equal to 3.0 μ

m; and

the height of the convex portion having the first height and the height of the convex portion having the second height are less than or equal to 6.7% of the distance.

12. A liquid crystal display device comprising:

a convex portion having a first height, and a convex portion having a second height, formed on a level surface on a first substrate;

a first region of a pixel electrode formed overlapping an upper edge portion of the convex portion having the first height, and an upper edge portion of the convex portion having the second height;

a second region of the pixel electrode formed in a side portion of the convex portion having the first height, and a side portion of the convex portion having the second height;

a third region of the pixel electrode formed on the level surface; and

an opposing electrode formed on a second substrate;

wherein;

the convex portion having the first height is relatively higher than the convex portion having the second height;

the distance from the opposing electrode formed on the second substrate to the third region of the pixel electrode is less than or equal to 3.0 μ

m; and

the height of the convex portion having the first height and the height of the convex portion having the second height are less than or equal to 6.7% of the distance.

13. A liquid crystal display device comprising:

a pixel electrode formed on;

a convex portion formed on a level surface on a first substrate;

a side face of the convex portion; and

the level surface; and

an opposing electrode formed on a second substrate.