Liquid crystal display element with electrode having concave-convex surface at liquid crystal side

• US 5,283,675 A
• Filed: 08/28/1992
• Issued: 02/01/1994
• Est. Priority Date: 08/30/1991
• Status: Expired due to Fees

• Current Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Original Assignee: AG Technology Co., Ltd.
• Inventors: Niiyama, Satoshi, Ooi, Yoshiharu, Hirai, Yoshinori, Wakabayashi, Tsuneo
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/936,633
• Time in Patent Office: 522 Days
• Field of Search: 359/40, 359/41, 359/51, 359/87
• US Class Current: 349/86
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133397 for suppressing after-image or image-sticking
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/1343 Electrodes reflective electrodes G02F1/133553
• CPC Class Codes: G02F 2203/30 Gray scale

Abstract

A liquid crystal display element comprises a liquid crystal and solidified matrix composite, in which liquid crystal is dispersed and held in a solidified matrix, which is interposed between a pair of substrates with electrodes at least one of which is transparent, wherein at least one of the substrates with electrodes has a fine concave-convex electrode surface at the side for the liquid crystal and solidified matrix composite.

Claims

1. A liquid crystal display element comprising a pair of substrates, at least one of which is transparent, and a pair of electrodes in opposition to each other, at least one of which is transparent, and a liquid crystal and solidified matrix composite, in which liquid crystal is dispersed and held in a solidified matrix, which is interposed between said pair of electrodes, characterized in that the distances between the electrodes differ at various portions, wherein at least one of the electrodes has a fine concave-convex surface at the side facing the liquid crystal and solidified matrix composite, and the relation 0.03·

G<

Ra<

0.3·

G is satisfied where G is the mean electrode gap and Ra is the mean distance from a peak convex portion of said concave-convex surface to a plane parallel to said pair of substrates and cutting through the concave-convex surface such that the amount of the surface above the plane is the same as that below the plane, and the pitch P of said concave-convex surface is two or more times as large as the means diameter R_LC of liquid crystal droplets of said liquid crystal dispersed in said solidified matrix.

2. The liquid crystal display element according to claim 1, wherein the size L of each picture element is in a range of from about 30 μ

m to 200 μ

m, and the pitch P of said concave-convex surface is 100 μ

m or less and smaller than the size L.

3. The liquid crystal display element according to claim 1, wherein the refractive index of the solidified matrix agrees with the ordinary refractive index (n₀) of the liquid crystal used when a voltage is applied to the liquid crystal and solidified matrix composite.

9. The liquid crystal display element according to claim 1 or 4, wherein said electrode having said concave-convex surface has substantially thin and uniform thickness and is formed at a front surface of the substrate upon which incident light is projected.

10. The liquid crystal display element according to claim 1 or 4, wherein said liquid crystal and solidified matrix composite has a specific resistance greater than or equal to 5×

10⁹ Ω

·

cm.

11. The liquid crystal display element according to claim 1 or 4, wherein the refractive index anisotropy of the liquid crystal is greater than 0.18.

12. The liquid crystal display element according to claim 11, wherein the ordinary refractive index n₀ o the liquid crystal and the refractive index n_p of the solidified matrix satisfy the following relation:

space="preserve" listing-type="equation">n.sub.0 -0.03<

n.sub.p <

n.sub.0 +0.05.

13. The liquid crystal display element according to claim 1 or 4, wherein the volume fraction of the liquid crystal to the liquid crystal and solidified matrix composite is greater than 20%.

14. The liquid crystal display element according to claim 1 or 4, wherein the volume fraction of the liquid crystal to the liquid crystal and solidified matrix composite is greater than 35%.

15. The liquid crystal display element according to claim 1 or 4, wherein the volume fraction of the liquid crystal to the liquid crystal and solidified matrix composite is greater than 45% but less than 70%.

16. The liquid crystal display element according to claim 1 or 4, wherein said liquid crystal and solidified matrix composite are formed of a photo-curable compound.

17. The liquid crystal display element according to claim 16, wherein said photo-curable compound is an acryl compound.

18. The liquid crystal display element according to claim 16, wherein said photo-curable compound includes an acryl oligomer.

19. The liquid crystal display element according to claim 1 or 4, wherein a photo-sensitive layer is laminated to the substrate for use in optical recording.

20. The liquid crystal display element according to claim 1 or 4, wherein G is in the range of 8 μ

m to 12 μ

m.

21. The liquid crystal display element according to claim 20, wherein Ra is in the range of 0.3 μ

m to 3 μ

m.

22. The liquid crystal display element according to claim 20, wherein Ra is in the range of 0.4 μ

m to 1.5 μ

m.

4. A liquid crystal display element comprising a first transparent substrate having a transparent first electrode, and a second substrate having a second electrode in opposition to the first electrode, and a liquid crystal and solidified matrix composite which is interposed between said first and second electrodes, wherein liquid crystal is dispersed and held in a solidified matrix, characterized in that the distances between the electrodes differ at various portions, wherein the first electrode has a concave-convex electrode surface, and the second substrate has a reflecting layer, and the relation 0.03·

<

Ra<

0.3·

G is satisfied where G is the mean electrode gap and Ra is the mean distance from a peak portion of said concave-convex surface to a plane parallel to said pair of substrates and cutting through the concave-convex surface such that the amount of the surface above the plane is the same as that below the plane, and the pitch P of said concave-convex surface is two or more times as large as the means diameter R_LC of liquid crystal droplets of the liquid crystal dispersed in said solidified matrix.

5. The liquid crystal display element according to claim 4, wherein the size L of each picture element is in a range of from about 30 μ

m to 200 μ

m, and the pitch P of the concave-convex surface is 100 μ

m or less and smaller than the size L.

6. The liquid crystal display element according to claim 4, wherein said liquid crystal display element includes an optical interference multilayer disposed at the outer surface side of the substrate having a concave-convex surface, wherein said optical interference multilayer has low reflection.

7. The liquid crystal display element according to claim 4, wherein the second electrode is a reflection electrode formed of metal.

8. The liquid crystal display element according to claim 4, wherein the reflection of light is obtained by a combination of the second electrode, which is transparent, and a reflection layer.

23. A liquid crystal display apparatus comprising a liquid crystal display element which has a pair of substrates, a pair of electrodes, at least one of which is transparent, and a liquid crystal and solidified matrix composite disposed between the pair of electrodes, wherein the liquid crystal and solidified matrix composite includes liquid crystal dispersed and held in a solidified matrix, and a driving circuit to drive the liquid crystal display element, characterized in that the distances between the electrodes differ at various portions wherein at least one of the electrodes has a concave-convex surface at the side facing the liquid crystal and solidified matrix composite, wherein the relation 0.03·

G<

Ra<

0.3·

G is satisfied where G is the means electrode gap and Ra is the mean distance from a peak convex portion of said concave-convex surface to a plane parallel to said pair of substrates and cutting through the concave-convex surface such that the amount of the surface above the plane is the same as that below the plane, and the pitch P of said concave-convex surface is two or more times as large as the means diameter R_LC of liquid crystal droplets of said liquid crystal dispersed in said solidified matrix.

24. The liquid crystal display apparatus according to claim 23, wherein the liquid crystal display element is a reflection type liquid crystal display element in which one of the pair of substrates with electrodes is a substrate with a transparent electrode and having a concave-convex electrode surface, the other is a substrate having a flat surface and a reflection layer on that.

25. The liquid crystal display element according to claim 23 or 24, wherein one electrode is the transparent electrode and the other electrode is a reflective electrode formed of metal.

26. The liquid crystal display element according to claim 23 or 24, wherein one electrode is the transparent electrode, and reflection of light is obtained by a combination of the other electrode, which is transparent, and a reflection layer.

27. A projection type liquid crystal display apparatus which comprises:

a liquid crystal display element comprising a liquid crystal and solidified matrix composite, in which liquid crystal is dispersed and held in a solidified matrix composite, which is interposed between a pair of substrates with electrodes, at least one of which is transparent, characterized in that at least one of the electrodes has a concave-convex electrode surface at the side facing the liquid crystal and solidified matrix composite,

a driving circuit to drive the liquid crystal display element,

a projection light source for emitting light to the liquid crystal display element, and

a projection optical system for projecting the light from the liquid crystal display element onto a projection screen, wherein the relation 0.03·

G<

Ra<

0.3·

G is satisfied, where G is the mean electrode gap, and Ra is the mean distance from a peak convex portion of said concave-convex surface to a plane parallel to said pair of substrates and cutting through the concave-convex surface such that the amount of the surface above the plane is the same as that below the plane, and the pitch P of said concave-convex surface is two or more times as large as the mean diameter R_LC of liquid crystal droplets of the liquid crystal dispersed in said solidified matrix.

28. The projection type liquid crystal display apparatus according to claim 27, wherein the liquid crystal display element is a reflection type liquid crystal display element in which one of the pair of substrates with an electrode is a substrate with a transparent electrode and having a concave-convex electrode surface, the other is a substrate having a reflection layer.

29. The projection type liquid crystal display apparatus according to claim 28, wherein said projection type liquid crystal display apparatus includes an optical interference multilayer disposed at the outer surface side of the substrate having a concave-convex surface of the liquid crystal display element, wherein said optical interference multilayer has low reflection.

30. The projection type liquid crystal display apparatus according to claim 28, wherein the refractive index of the solidified matrix agrees with the ordinary refractive index (n₀) of the liquid crystal used when a voltage is applied to the liquid crystal and solidified matrix composite.

31. The projection type liquid crystal display apparatus according to claim 28, wherein a device for reducing diffusion light is disposed in a path of light from the liquid crystal display element.

32. The projection type liquid crystal display apparatus according to claim 27 or 28, wherein the size L of each picture element of the liquid crystal display element is in a range of rom about 30 μ

m to 200 μ

m, and the pitch P of said concave-convex surface is 100 μ

m or less and smaller than the size L.