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

• US 5,386,306 A
• Filed: 05/22/1992
• Issued: 01/31/1995
• 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, Shidoji, Eiji, Gunjima, Tomoki, Yuki, Masanori, Hirai, Yoshinori, Kunigita, Masaya
• Primary Examiner(s): Crane, Sara W.
• Application Number:
  US07/886,946
• Time in Patent Office: 984 Days
• Field of Search: 359/51, 359/52, 359/45, 359/94, 359/106
• US Class Current: 349/89
• 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 crystal 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. An active matrix type liquid crystal display element wherein liquid crystal polymer composite in which a nematic liquid crystal is dispersed and held in a polymer matrix having a refractive index which is substantially equal to an ordinary refractive index (n₀) of the liquid crystal is held between a first substrate on which at least a pixel electrode with an active element is provided and a second substrate on which at least a counter electrode is provided, wherein said polymer matrix is made of a light curable type polymer, said liquid crystal polymer composite layer is obtained by irradiating light to the solution in which the liquid crystal and the light curable type polymer are dissolved uniformly to cause the solution to cure, a specific resistance of said liquid crystal polymer composite is higher than 5×

10⁹ Ω

cm, an average particle diameter R(μ

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

m, an electrode substrate distance d₀ is substantially 8 to 13 μ

m, and a maximum root mean square of applied voltage for said liquid crystal polymer composite is lower than or equal to 10 volts.

2. An active matrix type liquid crystal display element as set forth in claim 1, wherein said polymer is a light curable vinyl polymer.

3. An active matrix type liquid crystal display element as set forth in claim 1, wherein the light irradiating for the solution is ultraviolet ray.

4. An active matrix type liquid crystal display element as set forth in claim 1, wherein said active element is a polysilicon thin film transistor.

5. An active matrix type liquid crystal display element as set forth in claim 1, wherein said active element is a MIM element.

6. An active matrix type liquid crystal display element as set forth in claim 1, wherein said active element is a PIN diode.

7. An active matrix type liquid crystal display element as set forth in claim 1, wherein said electrode is a reflective electrode and used as of the reflection type liquid crystal display element.

8. An active matrix type liquid crystal display element as set forth in claim 1, further comprising:

color filters to combine with the liquid crystal display element to make a color display.

9. A projection type active matrix type liquid crystal display element comprising:

a liquid crystal display element having a liquid crystal polymer composite in which a nematic liquid crystal is dispersed and held in a polymer matrix having a refractive index which is substantially equal to an ordinary refractive index (n₀) of the liquid crystal is held between a first substrate on which at least a pixel electrode with an active element is provided and a second substrate on which at least a counter electrode is provided, wherein said polymer matrix is made of a light curable type polymer, said liquid crystal polymer composite layer is obtained by irradiating light to the solution in which the liquid crystal and the light curable type polymer are dissolved uniformly to cause the solution to cure, a specific resistance of said liquid crystal polymer composite is higher than 5×

10⁹ Ω

cm, an average particle diameter R(μ

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

m, an electrode substrate distance d₀ is substantially 8 to 13 μ

m, and a maximum root mean square of applied voltage for said liquid crystal polymer composite is lower than or equal to 10 volts.

10. A projection type active matrix type liquid crystal display device as set forth in claim 9, further comprising:

a projection light source for projecting light onto said liquid crystal display element;

an optical system of projection for projecting an image from said liquid crystal display element; and

a device for reducing diffused light located in the optical system of projection or between the optical system of projection and a projection screen.

11. A projection type active matrix type liquid crystal display device as set forth in claim 9, further comprising:

a projection light source for projecting light onto said liquid crystal display element;

an optical system of projection for projecting an image from said liquid crystal display element; and

a device for reducing diffused light located in the optical system of projection or between the optical system of projection and a projection screen, wherein said device for reducing diffused light is an aperture or a spot disposed on a passage of light.

12. A projection type active matrix type liquid crystal display device as set forth in claim 9, further comprising:

a projection light source for projecting light onto said liquid crystal display element;

an optical system of projection for projecting an image from said liquid crystal display element; and

a device for reducing diffused light located in the optical system of projection or between the optical system of projection and a projection screen wherein the device for reducing diffused light is a mirror having a small surface area which is disposed on a passage of light.

13. A projection type active matrix type liquid crystal display device as set forth in claim 9, further comprising:

a projection light source for projecting light onto said liquid crystal display element;

an optical system of projection for projecting an image from said liquid crystal display element; and

a device for reducing diffused light located in the optical system of projection or between the optical system of projection and a projection screen, the projection screen further comprising;

means for separating light from the projection light source into lights of three colors of R, G and B;

means for passing the light of three colors through respective active matrix liquid crystal display elements; and

means for synthesizing light emitted from the liquid crystal display elements to project them through the optical system of projection.