LCD-cell including one spacer exhibiting a dimension and a material property different from another spacers dimension and material property

• US 6,876,423 B2
• Filed: 04/23/2002
• Issued: 04/05/2005
• Est. Priority Date: 04/30/2001
• Status: Expired due to Term

• Current Assignee: AEG Gesellschaft
• Original Assignee: AEG Gesellschaft Fuer Moderne Informationssysteme Mbh
• Inventors: Bader, Otto, Bitter, Thomas, Bayrle, Reiner
• Primary Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US10/128,069
• Publication Number:
  US 20020171799A1
• Time in Patent Office: 1,078 Days
• Field of Search: 349/155, 349/156
• US Class Current: 349/155
• CPC Class Codes: G02F 1/13392 spacers dispersed on the cell substrate, e.g. spherical particles, microfibres

Abstract

A liquid crystal display (LCD) cell is provided having transparent plates that are substantially parallel to each other and contain a liquid crystal display material. A plurality of spacers are interposed between the transparent plates to define a distance between the plates. At least one of the spacers exhibits dimensions and properties different than another of the spacers. The different dimensions and properties operate to control the distance at various temperatures to prevent non-uniform color effects and vacuum void formations.

Claims

1. An LCD-cell having transparent plates sealingly connected with a liquid crystal material disposed between the transparent plates, the LCD-cell comprising:

a plurality of spacers interposed between the transparent plates, at least one of the spacers exhibiting a first dimension and a first material property, at least one other spacer exhibiting a second dimension different from the first dimension and a second material property different from the first material property, the plurality of spacers cooperable to define a distance between inner surfaces of the transparent plates;

wherein a sum of an average value of a heated expansion of the at least one spacer perpendicular to the inner surfaces and a one to threefold variance thereof is smaller than a difference of an average value of a heated expansion of the at least one other spacer perpendicular to the inner surfaces and a one to threefold variance thereof expressed by the formula

μ

₁+i·

σ

₁<

μ

₂−

i·

σ

₂,

where i=1, 2, 3;

μ

₁ and μ

₂ are the average of the dimensions of the spacers; and

σ

₁ and σ

₂ designate variance.

2. The LCD-cell of claim 1, wherein the first dimension of the at least one spacer is substantially equal to the distance between the inner surfaces when the LCD-cell is at a temperature substantially equal to an external ambient temperature.

3. The LCD-cell of claim 1, wherein the first material properly has a greater structural strength than the liquid crystal material.

4. The LCD-cell of claim 3, wherein the greater structural strength is at least equivalent to a structural strength of glass.

5. The LCD-cell of claim 1, wherein the first material property has a heat expansion coefficient less than the liquid crystal material.

6. The LCD-cell of claim 1, wherein the at least one spacer is adhesively affixed on at least one of the inner surfaces.

7. The LCD-cell of claim 1, wherein the second dimension of the at least one other spacer is greater than the distance between the inner surfaces when the LCD-cell is heated to a temperature above an external ambient temperature.

8. The LCD-cell of claim 1, wherein the second material property has a structural strength less than the first material property.

9. The LCD-cell of claim 8, wherein the transparent plates are disposed substantially parallel to each other, the second material property exhibiting the lesser structural strength at least in a direction perpendicular to the transparent plates.

10. The LCD-cell of claim 1, wherein the second material property has a higher heat expansion coefficient than the first material property.

11. The LCD-cell of claim 1, wherein the plurality of spacers are interposed between the transparent plates such that the transparent plates exhibit a pre-determined elasticity.

12. The LCD-cell of claim 11, wherein the at least one spacer, upon cooling of the LCD-cell to a temperature less than an external ambient temperature, prevents a vacuum void formation in the liquid crystal material.

13. The LCD-cell of claim 1, wherein the plurality of spacers are interposed between the transparent plates such that the transparent plates exhibit a pre-determined heat expansion capability.

14. The LCD-cell of claim 1, wherein the plurality of spacers are dispersed in the liquid crystal material disposed between the transparent plates such that the at least one spacer is smaller than the at least one other spacer in a direction between the inner surfaces.

15. The LCD-cell of claim 14, wherein the plurality of spacers are a plurality of first spacers and a plurality of second spacers, the pluralities of first and second spacers dispersed in the liquid crystal material between the transparent plates such that a majority of the first spacers is smaller in the direction between the inner surfaces than a majority of the second spacers when the LCD-cell is at or above an external ambient temperature.

16. The LCD-cell of claim 1, wherein the plurality of spacers exhibit a reduced density in their entirety, the reduced density configured to reduce light dispersion and absorption and improve optical quality of the LCD-cell.

17. An LCD-cell having transparent plates sealingly connected with a liquid crystal material disposed between the transparent plates, the LCD-cell comprising:

a plurality of spacers interposed between the transparent plates, at least one of the spacers exhibiting a first dimension and a first material property, at least one other spacer exhibiting a second dimension different from the first dimension and a second material property different from the first material property, the plurality of spacers cooperable to define a distance between inner surfaces of the transparent plates;

wherein a sum of an average value of an expansion of the at least one spacer perpendicular to the inner surfaces and a variance thereof is smaller than a difference of an average value of an expansion of the at least one other spacer perpendicular to the inner surfaces and a variance thereof express by the formula;

μ

₁+i·

σ

₁<

μ

₂−

i·

σ

₂,

where i=1;

μ

₁ and μ

₂ are the average of the dimensions of the spacers; and

σ

₁ and σ

₂ designate variance.

18. The LCD-cell of claim 17, wherein the first dimension of the at least one spacer is substantially equal to the distance between the inner surfaces when the LCD-cell is at a temperature substantially equal to an external ambient temperature.

19. The LCD-cell of claim 17, wherein the first material properly has a greater structural strength than the liquid crystal material.

20. The LCD-cell of claim 19, wherein the greater structural strength is at least equivalent to a structural strength of glass.

21. The LCD-cell of claim 17, wherein the first material property has a heat expansion coefficient less than the liquid crystal material.

22. The LCD-cell of claim 17, wherein the at least one spacer is adhesively affixed on at least one of the inner surfaces.

23. The LCD-cell of claim 17, wherein the second dimension of the at least one other spacer is greater than the distance between the inner surfaces when the LCD-cell is heated to a temperature above an external ambient temperature.

24. The LCD-cell of claim 17, wherein the second material property has a structural strength less than the first material property.

25. The LCD-cell of claim 24, wherein the transparent plates are disposed substantially parallel to each other, the second material property exhibiting the lesser structural strength at least in a direction perpendicular to the transparent plates.

26. The LCD-cell of claim 17, wherein the second material property has a higher heat expansion coefficient than the first material property.

27. The LCD-cell of claim 17, wherein the plurality of spacers are interposed between the transparent plates such that the transparent plates exhibit a pre-determined elasticity.

28. The LCD-cell of claim 27, wherein the at least one spacer, upon cooling of the LCD-cell to a temperature less than an external ambient temperature, prevents a vacuum void formation in the liquid crystal material.

29. The LCD-cell of claim 17, wherein the plurality of spacers are interposed between the transparent plates such that the transparent plates exhibit a pre-determined heat expansion capability.

30. The LCD-cell of claim 17, wherein the plurality of spacers are dispersed in the liquid crystal material disposed between the transparent plates such that the at least one spacer is smaller than the at least one other spacer in a direction between the inner surfaces.

31. The LCD-cell of claim 30, wherein the plurality of spacers are a plurality of first spacers and a plurality of second spacers, the pluralities of first and second spacers dispersed in the liquid crystal material between the transparent plates such that a majority of the first spacers is smaller in the direction between the inner surfaces than a majority of the second spacers when the LCD-cell is at or above an external ambient temperature.

32. The LCD-cell of claim 17, wherein the plurality of spacers is a mixture, consisting of the at least one spacer and the at least one other spacer, such that the density of spacers is reduced to yield improved optical characteristics.