Active matrix liquid crystal display element and projection type active matrix liquid crystal display device

• US 5,150,232 A
• Filed: 09/27/1989
• Issued: 09/22/1992
• Est. Priority Date: 10/04/1988
• Status: Expired due to Term

• Current Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: Gunkima, Tomoki, Yoshikawa, Yukio, Shidoji, Eiji, Yuki, Masanori, Hirai, Yoshinori, Kunigita, Masaya
• Primary Examiner(s): James, Andrew J.
• Assistant Examiner(s): Crane, Sara W.
• Application Number:
  US07/413,072
• Time in Patent Office: 1,091 Days
• Field of Search: 350/333, 357/23.7, 359/51, 359/53, 359/81, 359/94
• 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

Abstract

An active matrix liquid crystal display element and a projection type active matrix liquid crystal display device by which a display can be obtained which is good in color balance and high in brightness and also in contrast ratio. The display element includes a liquid crystal material held between an active matrix substrate and a counter electrode substrate. The liquid crystal material is formed from a liquid crystal polymer composite wherein nematic liquid is contained dispersively in a polymer matrix having a refractive index which coincides with the ordinary refractive index of the liquid crystal used, and a silicon thin film transistor is used as an active element on the active matrix substrate. The display device includes such an active matrix liquid crystal display element, a light source for projection light, and an optical system of projection.

Claims

1. A projection type active matrix liquid crystal display device of the type which includes an active matrix liquid crystal display element wherein a liquid crystal polymer composite comprised of nematic liquid crystal dispersively contained in a polymer matrix having a refractive index which is substantially equal to the ordinary refractive index (n_o) of the liquid crystal used 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, a light source for projection light, and an optical system of projection, characterized in that the anisotropy of refractive index Δ

n of the nematic liquid crystal used is greater than 0.18, and the average particle diameter R(μ

m) of the liquid crystal dispersively contained in the polymer matrix and the distance d(μ

m) between the active matrix substrate and the counter electrode substrate satisfy the relationships of

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

R·

Δ

n 0.7 (1)

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

d<

8 R (2)

2. A projection type active matrix liquid crystal display device as set forth in claim 1, characterized in that the maximum root mean square of applied voltage V(V) applied to the liquid crystal polymer composite satisfies the relationship of

19. An active matrix liquid crystal display element as set forth in claim 1, characterized in that the polymer used for the liquid crystal polymer composite is a light curable vinyl polymer, and the liquid crystal polymer composite used is obtained by irradiating light to solution in which the liquid crystal and the light curable vinyl polymer are dissolved uniformly to cause the resin to cure.

3. A projection type active matrix liquid crystal display device which includes an active matrix liquid crystal display element wherein a liquid crystal material 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, a light source for projection light, and an optical system of projection, characterized in that the liquid crystal material used is a liquid crystal polymer composite wherein nematic liquid crystal is dispersively contained in a polymer matrix having a refractive index which coincides with the ordinary refractive index (n_o) of the liquid crystal used, and the anisotropy of refractive index Δ

n of the nematic liquid crystal used in greater than 0.18 while the average particle diameter R(μ

m) of the liquid crystal dispersively contained in the polymer matrix and the distance d(μ

m) between the active matrix substrate and the counter electrode substrate satisfy the relationships of

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

R·

Δ

n<

0.7 (1)

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

d<

8 R (2)

4. A projection type active matrix liquid crystal display device as set forth in claim 3, characterized in that a polysilicon thin film transistor is used as the active element.

20. An active matrix liquid crystal display element as set forth in claim 3, characterized in that the polymer used for the liquid crystal polymer composite is a light curable vinyl polymer, and the liquid crystal polymer composite used is obtained by irradiating light to solution in which the liquid crystal and the light curable vinyl polymer are dissolved uniformly to cause the resin to cure.

5. A projection type active matrix liquid crystal display device of the type which includes a plurality of colored light sources, a plurality of active matrix liquid crystal display elements for individually receiving light from said colored light sources, and an optical system of projection for combining light emerging from said active matrix liquid crystal display elements and projecting the thus combined light, characterized in that each of said active matrix liquid crystal display elements is constituted such that nematic liquid crystal is dispersively contained in a polymer matrix 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, and the refractive indices of the resin matrices substantially coincide with the ordinary refractive indices (n_o) of the liquid crystal used and the anisotropies of refractive index Δ

n of the liquid crystal used are greater than 0.18 while the average particle diameters R_x (μ

m) of the liquid crystal of the individual colors dispersively contained in the polymer matrices, the distances d_x (μ

m) between the active matrix substrates and the counter electrodes and the dominant wavelengths λ

_x of the colors of the individual light sources have the following relationship to the average particle diameter R_G (μ

m) and the electrode distance d_G (μ

m) where the dominant wavelength λ

_G of the light source of green is λ

_G =540 nm ##EQU9##

6. A projection type active matrix liquid crystal display device as set forth in claim 5, characterized in that said liquid crystal display device is composed of three colored light sources of red, green and blue and three active matrix liquid display elements, and the average particle diameters R_R, R_G and R_B of the liquid crystal of the three colored liquid crystal display elements, the electrode distances d_R, d_G and d_B and the dominant wavelengths λ

_R, λ

_G and λ

_B of the colors of the individual light sources satisfy the relationships of ##EQU10##

7. A projection type active matrix liquid crystal display device as set forth in claim 5, characterized in a polysilicon thin film transistor is used as the active element.

8. A projection type active matrix liquid crystal display device as set forth in claim 5, characterized in that a device for reducing diffused light is interposed in said optical system of projection or between said optical system of projection and a projection screen.

21. An active matrix liquid crystal display element as set forth in claim 5, characterized in that the polymer used for the liquid crystal polymer composite is a light curable vinyl polymer, and the liquid crystal polymer composite used is obtained by irradiating light to solution in which the liquid crystal and the light curable vinyl polymer are dissolved uniformly to cause the resin to cure.

9. A projection type active matrix liquid crystal display device of the type which includes a plurality of colored light sources, a plurality of active matrix liquid crystal display elements for individually receiving light from said colored light sources, and an optical system of projection for combining light emerging from said active matrix liquid crystal display elements and projecting the thus combined light, characterized in that each of said active matrix liquid crystal display elements is constituted such that nematic liquid crystal having a positive dielectric anisotropy is dispersively contained in a polymer matrix 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, and the refractive index of the polymer matrix substantially coincides with the ordinary refractive index (n_o) of the liquid crystal used and the anisotropy of refractive index Δ

n of the liquid crystal used is greater than 0.18 while the average particle diameters R(μ

m) of the liquid crystals of the individual colors dispersively contained in the polymer matrices, the electrode distances d_x (μ

m) for the colors and the dominant wavelengths λ

_x of the colors of the individual light sources have the following relationship to the electrode distance d_G (μ

m) where the dominant wavelength λ

_G of the light source of green is λ

_G =540 nm ##EQU11##

10. A projection type active matrix liquid crystal display device as set forth in claim 9, characterized in that said liquid crystal display device is composed of three colored light sources of red, green and blue and three active matrix liquid display elements, and the electrode distances d_R, d_G and d_B of said liquid crystal display elements for the three colors and the dominant wavelengths λ

_R, λ

_G and λ

_B of the colors of the individual light sources satisfy the following relationship ##EQU12##

11. A projection type active matrix liquid crystal display device as set forth in claim 9, characterized in a polysilicon thin film transistor is used as the active element.

12. A projection type active matrix liquid crystal display device as set forth in claim 9, characterized in that a device for reducing diffused light is interposed in said optical system of projection or between said optical system of projection and a projection screen.

22. An active matrix liquid crystal display element as set forth in claim 9, characterized in that the polymer used for the liquid crystal polymer composite is a light curable vinyl polymer, and the liquid crystal polymer composite used is obtained by irradiating light to solution in which the liquid crystal and the light curable vinyl polymer are dissolved uniformly to cause the resin to cure.

13. An active matrix liquid crystal display element of the type which includes a plurality of color filters disposed therein, characterized in that nematic liquid crystal having a positive dielectric anisotropy is dispersively contained in a polymer matrix 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, and the refractive index of the polymer matrix substantially coincides with the dominant refractive index (n_o) of the liquid crystal used and the anisotropy of refractive index Δ

n of the liquid crystal used is greater than 0.18 while the average particle diameter R(μ

m) and the electrode distances d_x (μ

m) of the liquid crystal of the individual colors dispersively contained in the polymer matrix and the dominant wavelengths λ

_x of transmission light through the individual color filters have the following relationships to the electrode distance d_G (μ

m) where the dominant wavelength λ

_G of the light source of green is λ

_G =540 nm ##EQU13##

14. A projection type active matrix liquid crystal display device as set forth in claim 13, characterized in that said liquid crystal display element is an active matrix liquid crystal display element having three color filters for red, green and blue, and the electrode distances d_R, d_G and d_B of the liquid crystal display element corresponding to the three color filters and the dominant wavelengths λ

_R, λ

_G and λ

_B of transmission lights through the individual color filters satisfy the following relationship ##EQU14##

16. A projection type active matrix liquid crystal display device as set forth in claim 13, characterized in that said liquid crystal display device is composed of three color filters of red, green and blue and three active matrix liquid crystal display elements, and the electrode distances d_R, d_G and d_B of the liquid crystal display elements for the three colors and the dominant wavelengths λ

_R, λ

_G and λ

_B of transmission lights of the individual color filters satisfy the following relationship ##EQU16##

18. A projection type active matrix liquid crystal display device as set forth in claim 16, characterized in that a device for reducing diffused light is interposed in said optical system of projection or between said optical system of projection and a projection screen.

23. An active matrix liquid crystal display element as set forth in claim 13, characterized in that the polymer used for the liquid crystal polymer composite is a light curable vinyl polymer, and the liquid crystal polymer composite used is obtained by irradiating light to solution in which the liquid crystal and the light curable vinyl polymer are dissolved uniformly to cause the resin to cure.

15. A projection type active matrix liquid crystal display device of the type which includes a projection light source, an active matrix liquid crystal display element having a plurality of color filters disposed thereon, and an optical system of projection for projecting light emerging from said active matrix liquid crystal display element, characterized in that said active matrix liquid crystal display element is composed of nematic liquid crystal having a positive dielectric anisotropy and dispersively contained in a polymer matrix 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, and the refractive index of the polymer matrix substantially coincides with the ordinary refractive index (n_o) of liquid crystal used and the anisotropy of refractive index Δ

n of the liquid crystal used is greater than 0.18 while the average particle diameter R(μ

m) and the electrode distances d_x (μ

m) of the liquid crystal of the individual colors dispersively contained in the polymer matrix and the dominant wavelength λ

_x of transmission light through the individual color filters have the following relationship to the electrode distance d_G where the dominant wavelength λ

_G of the light source of green is λ

_G =540 nm ##EQU15##

17. A projection type active matrix liquid crystal display device as set forth in claim 15, characterized in that a polysilicon thin film transistor is used as the active element.

24. An active matrix liquid crystal display element as set forth in claim 15, characterized in that the polymer used for the liquid crystal polymer composite is a light curable vinyl polymer, and the liquid crystal polymer composite used is obtained by irradiating light to solution in which the liquid crystal and the light curable vinyl polymer are dissolved uniformly to cause the resin to cure.