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

• US 6,122,021 A
• Filed: 11/30/1994
• Issued: 09/19/2000
• Est. Priority Date: 10/04/1988
• Status: Expired due to Fees

• Current Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: Yoshikawa, Yukio, Yuki, Masanori, Kunigita, Masaya, Niiyama, Satoshi, Shidoji, Eiji, Gunjima, Tomoki, Hirai, Yoshinori
• Primary Examiner(s): TON, MINH TOAN T
• Application Number:
  US08/350,175
• Time in Patent Office: 2,120 Days
• Field of Search: 359/51, 359/52, 359/102, 349/86, 349/89, 349/93, 349/10
• US Class Current: 349/10
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 2202/40 Materials having a particular birefringence, retardation
• CPC Class Codes: G09F 19/18 involving the use of optical projection means, e.g. projection of images on clouds projection apparatus per se G03B
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3144 Cooling systems cooling of liquid crystal cells in general G02F1/133382; cooling of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/16

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 device comprising:

a liquid crystal display element comprising;

(i) a first substrate with a pixel electrode drive by an active element for said pixel electrode;

(ii) a second substrate with a counter electrode; and

(iii) a liquid crystal polymer composite, held between said first substrate and said second substrate comprised of a nematic liquid crystal dispersively contained in a polymer matrix having a refractive index which is substantially equal to the ordinary index (no) of said nematic liquid crystal used,

wherein said nematic liquid crystal has an anisotropy of refractive index 0.18≦

Δ

n; and

wherein the anisotropy of relative dielectric constant (Δ

ε

_LC) is 5<

Δ

ε

_LC <

13.

2. The liquid crystal display device of claim 1, wherein said liquid crystal polymer composite comprises a polymer matrix having a large number of fine holes formed therein wherein said liquid crystal fills in the holes of said polymer matrix to form microcapsules.

3. The liquid crystal display device of claim 2, wherein said microcapsules, are completely independent of each other.

4. The liquid crystal display device of claim 2, wherein said microcapsules are connected partially with each other.

5. The liquid crystal display device of claim 2, wherein said nematic liquid crystal has an anisotropy of relative dielectric constant (Δ

ε

_LC)≧

11.6.

6. The liquid crystal display device of claim 5, wherein said nematic liquid crystal has an anisotropy of relative dielectric constant (Δ

ε

_LC) of about 10.

7. The liquid crystal display device of claim 1, wherein the average particle diameter R(μ

m) of the liquid crystal dispersively contained in said polymer matrix satisfies the relationship

space="preserve" listing-type="equation">0.3<

R·

Δ

n<

0.7 (1B).

8. The liquid crystal display device of claim 1, wherein the distance d (μ

m) between said pixel electrode and said counter-electrode satisfies the relationship

space="preserve" listing-type="equation">4R<

d<

8R (2B).

9. The liquid crystal display device of claim 1, wherein the maximum root mean square of applied voltage for said liquid crystal polymer composite is ≧

10 volts,.

10. The liquid crystal display device of claim 1, wherein said nematic liquid crystal has an anisotropy of relative dielectric constant (Δ

ε

_LC)≧

11.6.

11. The liquid crystal display device of claim 10, wherein said nematic liquid crystal has an anisotropy of relative dielectric constant (Δ

ε

_LC) of about 10.

12. A liquid crystal display element comprising:

(i) a first substrate with a first electrode;

(ii) a second substrate with a second electrode; and

(iii) a liquid crystal polymer composite, held between said first substrate and said second substrate comprised of a nematic liquid crystal dispersively contained in a polymer matrix having a refractive index which is substantially equal to the ordinary index (n_o) of said nematic liquid crystal used,

wherein said nematic liquid crystal has an anisotropy of refractive index 0.18≦

Δ

n;

the average particle diameter R(μ

m) of the liquid crystal dispersively contained in said polymer matrix satisfies the relationship

space="preserve" listing-type="equation">0.3<

R·

Δ

n<

0.7 (1B); and

the distance d (μ

m) between said first electrode and said second electrode satisfies the relationship

space="preserve" listing-type="equation">4R<

d<

8R (2B).

13. The liquid crystal display element of claim 12, wherein said liquid crystal polymer composite comprises a polymer matrix having a large number of fine holes formed therein wherein said liquid crystal fills in the holes of said polymer matrix to form microcapsules.

14. The liquid crystal display device of claim 13, wherein said microcapsules, are completely independent of each other.

15. The liquid crystal display device of claim 13, wherein said microcapsules are connected partially with each other.

16. The liquid crystal display device of claim 12, wherein the maximum root mean square of applied voltage for said liquid crystal polymer composite is ≦

10 volts.

17. The liquid crystal display device of claim 12, wherein the maximum root mean square of applied voltage V(V) applied to the liquid crystal polymer composite satisfies the relationship

18. An active matrix type liquid crystal display element comprising:

(i) a first substrate with a pixel electrode drive by an active element for said pixel electrode;

(ii) a second substrate with a counter electrode; and

(iii) a liquid crystal polymer composite, held between said first substrate and said second substrate comprised of a nematic liquid crystal dispersively contained in a polymer matrix having a refractive index which is substantially equal to the ordinary index (n_o) of said nematic liquid crystal used,

wherein a specific resistance of said liquid crystal polymer composite is >

5×

10⁹ Ω

·

cm;

the average particle diameter R(μ

m) of the liquid crystal dispersively contained in said polymer matrix is substantially uniform and 1.5 to 2.5 μ

m;

the distance d (μ

m) between said first electrode and said second electrode is 8 to 13 μ

m; and

the maximum root mean square of applied voltage for said liquid crystal polymer composite is ≦

10 volts.

19. The liquid crystal display element of claim 18, wherein said liquid crystal polymer composite comprises a polymer matrix having a large number of fine holes formed therein wherein said liquid crystal fills in the holes of said polymer matrix to form microcapsules which are completely independent of each other.

20. The liquid crystal display element of claim 18, wherein said liquid crystal polymer composite comprises a polymer matrix having a large number of fine holes formed therein wherein said liquid crystal fills in the holes of said polymer matrix to form microcapsules which are connected partially with each other.

21. The liquid crystal display element of claim 18, wherein said liquid crystal display element is provided with reflective means and used as a reflection type liquid crystal display element.

22. A projection liquid crystal display apparatus comprising a light source,

an optical system of projection;

and a liquid crystal display device comprising an active matrix liquid crystal element wherein a liquid crystal/polymer composite is held between an active matrix substrate on which an active element is provided for each pixel electrode and a counter electrode substrate on which a counter electrode is provided, said liquid crystal/polymer composite comprising a liquid crystal material having a positive dielectric constant and an anisotropy of refractive index An which is greater than or equal to 0.18, and having a volume fraction which is greater than or equal to 62% and less than 70%, the polymer matrix of the liquid crystal/polymer composite comprising polymerized units of acrylate and acrylic oligomer, and having pores formed therein; and

wherein

the specific resistance of said liquid crystal/polymer composite is higher than 5×

10⁸ Ω

cm;

the haze value of said liquid crystal/polymer composite is higher than 80% in a scattering condition and the transmittance is higher than 70%, and wherein the contrast ratio of said display is greater than 100.

23. The display apparatus according to claim 22 wherein the active element is a thin film transistor.

24. The display apparatus according to claim 22, wherein said display is a reflection display.

25. A composition comprising a liquid crystal and a photocurable acrylate monomer, said composition being useful for preparing a liquid crystal/polymer composite capable of exhibiting transparent and light scattering states, wherein Δ

n and Δ

ε

of said liquid crystal satisfy the following relationships;

Δ

n≧

0.18;

5<

Δ

ε

<

13.

26. The composition according to claim 25, wherein Δ

ε

<

11.6.

27. The composition according to claim 25, wherein Δ

n≧

0.20.

28. The composition according to claim 25, wherein Δ

n<

0.25.

29. The composition of claim 25, wherein said photocurable acrylate is a urethane acrylate oligomer.

30. The composition of claim 25, further comprising a photoinitiator.

31. The composition of claim 25, wherein Δ

n² /η

>

0.0014 wherein η

(cSt) is the viscosity of said liquid crystal.

32. The composition according to claim 25, wherein the volume fraction of liquid crystal in said composition is greater than 45%.

33. A liquid crystal optical element comprising:

a pair of substrates provides with electrodes, and

a liquid crystal and solidified matrix composite material, disposed between the pair of substrates, said composite material being capable of exhibiting transparent and scattering states, wherein Δ

n and Δ

ε

of said liquid crystal satisfy the following relationships;

Δ

n≧

0.18;

5<

Δ

ε

<

13.

34. A liquid crystal optical element according to claim 33, further comprising multiplex driving means for driving for said liquid crystal and solidified matrix composite.

35. A liquid crystal optical element according to claim 33, further comprising a static driving means for driving for said liquid crystal and solifified matrix composite.

36. A laser shutter device comprising a liquid crystal optical element according to claim 33.

37. A laser shutter device comprising a liquid crystal optical element according to claim 33.

38. A laser shutter device comprising a liquid crystal optical element according to claim 35.