Liquid crystal display and fabrication method

• US 6,233,034 B1
• Filed: 05/29/1998
• Issued: 05/15/2001
• Est. Priority Date: 12/29/1997
• Status: Expired due to Term

• Current Assignee: BOE HYDIS Technology Company Limited (SK Hynix Inc.)
• Original Assignee: Hyundai Electronics Industries Co. Ltd. (SK Hynix Inc.)
• Inventors: Lee, Jung Yeal, Lee, Seung Hee, Lee, Seok Lyul, Choi, Woo Ho
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US09/087,422
• Time in Patent Office: 1,082 Days
• Field of Search: 349/141, 349/143, 349/43
• US Class Current: 349/141
• 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

Abstract

Disclosed is a liquid crystal display comprising: a first substrate and a second substrate, the first substrate being disposed opposite the second substrate and being disposed a first distance apart, each of the substrates having an inner surface and an outer surface opposite the inner surface; a liquid crystal layer sandwiched between the inner surfaces of the substrates, the liquid crystal layer including a plurality of liquid crystal molecules; a first electrode formed on the inner surface of the first substrate, the first electrode having a first width; and a second electrode formed on the inner surface of the first substrate, the second electrode having a second width, and spaced apart from the first electrode by a second distance, the first electrode and the second electrode being capable of aligning the liquid crystal molecules using an electric field produced between the first electrode and the second electrode, wherein the first distance is greater in length than the second distance, and the first and second electrodes each has a width to such a degree that the liquid crystal molecules above the first and second electrodes are substantially aligned by the electric field.

Claims

1. A liquid crystal display comprising:

a first and second substrates, said first substrate being disposed opposite said second substrate a first distance apart, each of said substrates having an inner surface and an outer surface opposite the inner surface;

a liquid crystal layer sandwiched between the inner surfaces of the two substrates, said liquid crystal layer including a plurality of liquid crystal molecules;

a first electrode formed on the inner surface of the first substrate, the first electrode having a squared frame structure;

a second electrode formed on the inner surface of the first substrate, the second electrode comprising a plurality of strips, the strips each being disposed to overlap with the first electrode and to have a first width and a second distance therebetween, wherein surface of the first electrode is partially exposed through spaces between the strips, the exposed portions of the first electrode each having a width of the second distance; and

an insulating layer for insulating the first electrode and second electrode from each other,

wherein the first and second electrodes each is made of a transparent conductor,

wherein the first distance between the first and second substrates is greater than a thickness of the insulating layer, and the second distance and the first width are such that the liquid crystal molecules above the exposed portions of the first electrode and the strips of the second electrode are substantially aligned by the electric field produced between the exposed portions of the first electrode and the strips of the second electrode.

2. The liquid crystal display in claim 1, wherein the transparent conductor is ITO.

3. The liquid crystal display in claim 2, wherein a ratio of the width of the strip to the second distance between the strips of the second electrode is approximately in a range of 0.2 to 5.

4. The liquid crystal display in claim 3, wherein the width of the strip is approximately in a range of 1 μ

m to 8 μ

m.

5. The liquid crystal display in claim 4, wherein a ratio of the interval between the strips of the second electrode to the first distance between the first and second substrates is approximately in a range of 0.1 to 5.

6. The liquid crystal display in claim 5, wherein the first electrode further comprises a first connecting portion parallel to the first direction, for connecting one sided ends of the strips to each other, the first connecting portion being overlapped with the second electrode.

7. The liquid crystal display in claim 6, wherein the first electrode further comprises a second connecting portion parallel to the first direction, for connecting the other sided ends of the strips to each other, said second connecting portion being overlapped with said second electrode.

8. The liquid crystal display in claim 6, further comprising a first alignment layer formed on the inner surface of the first substrate and a second alignment layer formed on the inner surface of the second substrate, the first alignment layer having a first rubbing axis which differs by a first selected angle from the electric field direction, and aligning the liquid crystal molecules to a direction of the first rubbing axis in an absence of the electric field, and the second alignment layer having a second rubbing axis which differs by a second selected angle from the electric field direction, and arranging the liquid crystal molecules to a direction of the second rubbing axis in the presence of the electric field.

9. The liquid crystal display in claim 8, wherein the liquid crystal molecules have a pretilt angle, the pretilt angle being approximately in a range of 0 degree to 10 degrees.

10. The liquid crystal display in claim 9, wherein the first rubbing axis of the first alignment layer differs by 180 degree from the second rubbing axis of the second alignment layer.

11. The liquid crystal display in claim 10, further comprising a polarizer disposed on the outer surface of the first substrate and an analyzer disposed on the outer surface of the second substrate, the polarizer having a polarizing axis in a given direction, the polarizing axis being optically related with the liquid crystal layer, the analyzer having an absorbing axis in a given direction, the absorbing axis being optically related with the polarizer.

12. The liquid crystal display in claim 11, wherein an angle between the polarizing axis of the polarizer and the first rubbing axis of the first alignment layer is approximately in a range of 0 degree or 90 degrees, and an angle between the absorbing axis of the analyzer and the polarizing axis of the polarizer is approximately 90 degrees.

13. The liquid crystal display in claim 12, wherein when an angle between the first rubbing axis and the electric field direction is approximately in a range of 0 degree to 45 degrees, dielectric anisotropy of the liquid crystal layer is negative, while when an angle between the first rubbing axis and the electric field direction is approximately in a range of 45 degrees to 90 degrees, dielectric anisotropy of the liquid crystal is positive.

14. The liquid crystal display in claim 13, wherein the liquid crystal layer is a nematic liquid crystal, and a product of the anisotropy of the refractive index of the liquid crystal molecules in the liquid crystal layer and the first distance is approximately in a range of 0.2 μ

m to 0.6 μ

m.

15. The liquid crystal display in claim 1, wherein the liquid crystal layer is a nematic liquid crystal, and a product of the anisotropy of the refraction index of the liquid crystal molecules in the liquid crystal layer and the first distance is approximately in a range of 0.2 μ

m to 0.6 μ

m.

16. The liquid crystal display in claim 1, wherein the gate bus lines, data bus lines, and common signal lines are formed of one element metal or alloy of at least two elements selected from a group being comprised of Al, Mo, Ti, W, Ta, and Cr.

17. A method for fabricating a liquid crystal display, the method comprising:

providing a first transparent substrate;

forming a first transparent conductive layer on the first transparent substrate;

forming a first metal film on the first transparent conductive material;

patterning the first metal film such that said first transparent conductive layer is exposed, to form a plurality of gate bus lines and a common signal line;

patterning the first transparent conductor to form a plurality of second electrodes;

forming a gate insulator on the resulting structure including the gate bus lines, common signal lines, and second electrodes;

forming a channel layer on a selected portion of the gate insulating layer;

forming a second transparent conductive layer on the gate insulator;

patterning the second transparent conductive layer to overlap with the second electrode, to form a plurality of first electrodes;

depositing a second metal film on the gate insulating layer and then patterning the second metal film to form a plurality of data bus lines, sources and drains; and

forming a first alignment layer on the resultant structure.

18. The method in claim 17, wherein the first and second transparent conductive material is ITO.

19. A method for fabricating a liquid crystal display, the method comprising:

providing a first transparent substrate;

forming a first transparent conductive layer on the first transparent substrate;

patterning the first transparent conductive layer to form a plurality of second electrodes;

forming a first metal film on the first transparent conductive layer;

patterning the first metal film to form a plurality of gate bus lines and a common signal line such that the common signal line is contact with each of the second electrodes;

forming a gate insulating layer on the resultant structure including the gate bus lines, the common signal line, and the second electrodes;

forming a channel layer on a selected portion of the gate insulating layer;

forming a second transparent conductive layer on the gate insulating layer;

patterning the second transparent conductive layer to overlap with the second electrode, to form a plurality of first electrodes;

depositing a second metal film on the gate insulating layer and then patterning the second metal film, to form a plurality of data bus lines, sources and drains; and

forming a first alignment layer on the resultant structure,

wherein the forming a first metal film on the first transparent conductive layer and patterning the first metal film to form a plurality of gate bus lines and a common signal line, is exchangeable with the forming a first transparent conductive layer on the first transparent substrate and patterning the first transparent conductive layer to form a plurality of second electrodes.

20. The method of claim 19, wherein the first and second transparent conductive material is ITO.