Liquid crystal display element and a projection type liquid crystal display apparatus

• US 5,196,952 A
• Filed: 03/26/1992
• Issued: 03/23/1993
• Est. Priority Date: 03/27/1991
• Status: Expired due to Term

• Current Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Original Assignee: AG Technology Co., Ltd.
• Inventors: Niiyama, Satoshi, Gunjima, Tomoki, Hirai, Yoshinori
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/858,025
• Time in Patent Office: 362 Days
• Field of Search: 359/51, 359/52, 359/93, 359/102
• US Class Current: 349/10
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals

Abstract

A liquid crystal display element comprises a pair of substrates provided with electrodes and a liquid crystal and solidified matrix composite material, disposed between the pair of substrates, which includes a nematic liquid crystal dispersed and held in a solidified matrix, the nematic liquid crystal being such that the refractive index of the liquid crystal is changed depending on states of applying a voltage wherein in a state, the refractive index of the liquid crystal substantially coincides with that of the solidified matrix to thereby pass light, and in the other state, the former does not coincide with the latter to thereby cause the scattering of light, wherein the refractive index anisotropy Δn of the liquid crystal used is 0.18 or higher, and the dielectric anisotropy Δε_LC of the liquid crystal used satisfies the relation of 5<Δε_LC <13.

Claims

1. A liquid crystal display element comprising a pair of substrates provided with electrodes and a liquid crystal and solidified matrix composite material, disposed between the pair of substrates, which includes a nematic liquid crystal dispersed and held in a solidified matrix, said nematic liquid crystal being such that the refractive index of the liquid crystal is changed depending on states of applying a voltage wherein in a state, the refractive index of the liquid crystal substantially coincides with that of the solidified matrix to thereby pass light, and in the other state, the former does not coincide with the latter to thereby cause the scattering of light, characterized in that the refractive index anisotropy Δ

n of the liquid crystal used is 0.18 or higher, and the dielectric anisotropy Δ

ε

_LC of the liquid crystal used satisfies the relation of 5<

Δ

ε

_LC <

13.

2. The liquid crystal display element according to claim 1, wherein said liquid crystal and solidified matrix composite material is disposed between the pair of positive dielectric anisotropy is dispersed and held in a polymer matrix wherein the refractive index of the polymer matrix substantially agrees with the ordinary refractive index (n₀) of the liquid crystal used.

3. The liquid crystal display element according to claim 1, wherein the refractive index anisotropy Δ

n of the liquid crystal used is 0.18<

Δ

n<

0.25.

4. The liquid crystal display element according to claim 3, wherein the refractive index anisotropy Δ

n of the liquid crystal used is 0.20 or higher.

5. The liquid crystal display element according to claim 1, wherein the specific dielectric constant ε

_M of the liquid crystal and solidified matrix composite material at a sufficiently low voltage which is lower than its threshold voltage and the dielectric anisotropy of the liquid crystal used satisfy the relation of Δ

ε

_LC <

1.45 ε

_M.

6. The liquid crystal display element according to claim 1, wherein the average particle diameter R (μ

m) of the liquid crystal held in the liquid crystal and solidified matrix composite material satisfies the relation of 0.2<

R·

Δ

n<

0.7.

7. The liquid crystal display element according to claim 1, wherein the viscosity η

(cSt) of the liquid crystal in the liquid crystal and solidified matrix composite material satisfies the relation of Δ

n² /η

>

0.0014.

8. The liquid crystal display element according to claim 6, Wherein the elastic constant K33 (10^-12 N) of the liquid crystal in the liquid crystal and solidified matrix composite material satisfies the relation of 4(K33/η

)⁰.5 >

R>

(K33/Δ

ε

_LC)⁰.5.

9. The liquid crystal display element according to claim 1, wherein one of the pair of substrates provided with electrodes is an active matrix substrate having an active element for each electrode for picture element, the other is a counter electrode substrate provided with a counter electrode.

10. The liquid crystal display element according to claim 1, wherein the solidified matrix in the liquid crystal and solidified matrix composite material is obtained by irradiating light to an uncured mixture of a photo-curable compound and the liquid crystal followed by curing the mixture.

11. The liquid crystal display element according to claim 10, wherein the solidified matrix in the liquid crystal and solidified matrix composite material is obtained by uniformly dissolving the photo-curable compound in the liquid crystal to prepare solution, and by irradiating light to the solution to thereby cure the photo-curable compound.

12. A projection type liquid crystal display apparatus comprising in combination a projection light source, a projection optical system and a liquid crystal display element comprising an active matrix substrate having an active element for each electrode for picture element, a counter electrode substrate provided with a counter electrode and a liquid crystal and solidified matrix composite material, interposed between the active matrix substrate and the counter electrode, which includes a nematic liquid crystal dispersed and held in a solidified matrix, said nematic liquid crystal being such that the refractive index of the liquid crystal is changed depending on states of applying a voltage wherein in a state, the refractive index of the liquid crystal substantially coincides with that of the solidified matrix to thereby pass light, and in the other state, the former does not coincide with the latter to thereby cause the scattering of light, characterized in that the refractive index anisotropy Δ

n of the liquid crystal used for the liquid crystal and solidified matrix composite material is 0.18 or higher, and the dielectric anisotropy Δ

ε

_LC of the liquid crystal used satisfies the relation of 5<

Δ

ε

_LC <

13.

13. The projection type liquid crystal display apparatus according to claim 12, wherein said liquid crystal and solidified matrix composite material is disposed between the active matrix substrates and the counter electrode substrate in which a nematic liquid crystal having a positive dielectric anisotropy is dispersed and held in a polymer matrix wherein the refractive index of the polymer matrix substantially agrees with the ordinary refractive index (n₀) of the liquid crystal used.

14. The projection type liquid crystal display apparatus according to claim 12, wherein the specific dielectric constant ε

_M of the liquid crystal and solidified matrix composite material at a sufficiently low voltage which is lower than its threshold voltage and the dielectric anisotropy Δ

ε

_LC of the liquid crystal used satisfy the relation of Δ

ε

_LC <

1.45 ε

_M.

15. The projection type liquid crystal display apparatus according to claim 12, wherein the average particle diameter R (μ

m) of the liquid crystal held in the liquid crystal and solidified matrix composite material satisfies the relation of 0.2<

R·

Δ

n<

0.7.

16. The projection type liquid crystal display apparatus according to claim 12, wherein the solidified matrix in the liquid crystal and solidified matrix composite material is a photo-curable compound to be cured by the irradiation of light, and said liquid crystal and solidified matrix composite material is obtained by irradiating light to an uncured mixture of the photo-curable compound and the liquid crystal to thereby cure the photo-curable compound.

17. The projection type liquid crystal display apparatus according to claim 12, wherein a device for reducing diffusion light is disposed between the liquid crystal display element and the projection light system, or in the projection light system.

18. The projection type liquid crystal display apparatus according to claim 17, wherein the device for reducing diffusion light is an aperture.

19. The projection type liquid crystal display apparatus according to claim 12, wherein said projection light source comprises a light source and a dichloric means as a color-splitting optical system;

said projection optical system comprises a dichloric means as a color-synthesizing optical system and a projection lens, whereby light is splitted into three kinds of color R, G and B, each color light being passed through each liquid crystal display element, being subjected to color synthesis and the synthesized light being projected through the projection lens.

20. The projection type liquid crystal display apparatus according to claim 19, wherein a single device for reducing diffusion light is disposed near the projection lens.