Polymer dispersion type liquid crystal display element and reflection type liquid crystal display device

• US 5,342,545 A
• Filed: 12/31/1992
• Issued: 08/30/1994
• Est. Priority Date: 03/06/1992
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Yamada, Nobuaki, Onishi, Noriaki, Hirai, Toshiyuki, Kohzaki, Shuichi
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US07/999,138
• Time in Patent Office: 607 Days
• Field of Search: 252/299.01, 252/299.1, 252/299.2, 428/1, 359/62, 359/70, 359/265, 359/267, 359/51, 359/53, 359/94, 359/96, 359/99, 359/102
• US Class Current: 252/299.01
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13476 in which at least one liquid crystal cell or layer assumes a scattering state

Abstract

A polymer dispersion type liquid crystal display element includes two layers of polymer dispersion type liquid crystal layers being overlaid and having liquid crystal drops positive in dielectric anisotropy dispersed in a polymer in which light scattering and transmission are controlled electrically, a transparent support element for scattering light between the polymer dispersion type liquid crystal layers, being interposed and a liquid crystal display device having a colored reflector plate disposed on the back of one polymer dispersion type liquid crystal layer. In one of the two layers of polymer dispersion type liquid crystal layers, a liquid crystal layer containing a dichroic dye is dispersed, and coloring and light transmission are electrically controlled, and a white reflector plate is disposed on the back side of one of the polymer dispersion type liquid crystal layers to realize the liquid crystal display device. By composing the liquid crystal display element and liquid crystal display device in such constitutions, both light scattering capacity and contrast may be enhanced at the same time.

Claims

1. A polymer dispersion type liquid crystal display element comprising:

two layers of polymer dispersion type liquid crystal layers which comprise a polymer and liquid crystal drops positively dispersed in dielectric anisotropy in said polymer;

at least said two layers overlaid one over another for controlling the light scattering and transmission electrically with a range of thickness for said polymer dispersion type liquid crystal layers comprising 5 μ

m to 18 μ

m; and

a transparent support element for scattering light interposed between said polymer dispersion type liquid crystal layers with a range of thickness for said transparent support element for scattering light comprising 10 μ

m to 10 mm.

2. A polymer dispersion type liquid crystal display element of claim 1, wherein said range of thickness for said transparent support element for scattering light comprises 50 μ

m to 200 μ

m, and said range of thickness for said polymer dispersion type liquid crystal layers comprises 10 μ

m to 15 μ

m.

5. A polymer dispersion type liquid crystal display element of claim 1, wherein the material of said transparent support element for scattering light comprises a transparent substrate combining a plurality of transparent substrates differing in refractive index sequentially from one transparent substrate having the smallest refractive index to another transparent substrate having the largest refractive index and a microlens having a light diffusion effect.

7. A method of forming a polymer dispersion type liquid crystal display element of claim 1, wherein said thickness range for said polymer dispersion type liquid crystal layers formed at said step (c) comprises 10 μ

m to 15 μ

m.

8. A method of forming a polymer dispersion type liquid crystal display element of claim 1, wherein said thickness range for said transparent support element for scattering light at said step (e) comprises 50 μ

m to 200 μ

m.

9. A method of forming a polymer dispersion type liquid crystal display element of claim 1, further comprising the step of disposing a colored reflector plate on the back side of one of said polymer dispersion type liquid crystal layers.

3. A reflection type liquid crystal display device comprising:

two layers of polymer dispersion type liquid crystal layers which comprise a polymer and liquid crystal drops positively dispersed in dielectric anisotropy in said polymer;

at least said two layers overlaid one over another for controlling the light scattering and transmission electrically with a range of thickness for said polymer type liquid crystal layers comprising 5 μ

m to 18 μ

m;

a transparent support element for scattering light interposed between said polymer dispersion type liquid crystal layers with a range of thickness for said transparent support element for scattering light comprising 10 μ

m to 10 μ

mm; and

a colored reflector plate disposed on the back side of one of said polymer dispersion type liquid crystal

4. A reflection type liquid crystal display device comprising:

a first polymer dispersion type liquid crystal layer dispersing liquid crystal drops in a polymer for controlling the light scatter and transmission electrically with a range of thickness for said first polymer dispersion type liquid crystal layer comprising 5 μ

m to 18 μ

m;

a second polymer dispersion type liquid crystal layer dispersing liquid crystal drops containing dichroic dye in a polymer for controlling the coloring and light transmission electrically with a range of thickness for said second polymer dispersion type liquid crystal layer comprising 5 μ

m to 18 μ

m;

a transparent support element for scattering light interposed between said first and second polymer dispersion type liquid crystal layers with a range of thickness for said transparent support element for scattering light comprising 10 μ

m to 10 mm; and

a white reflector plate disposed on the back side of said first or second polymer dispersion type liquid crystal layer.

6. A method of forming a polymer dispersion type liquid crystal display element, comprising the steps of:

(a) positively dispersing liquid crystal drops in dielectric anisotropy in a polymer with two layers of polymer dispersion type liquid crystal layers comprising said polymer and said liquid crystal drops;

(b) overlaying at least said two layers one over another for controlling the light scattering and transmission electrically;

(c) forming a thickness for said polymer dispersion type liquid crystal layers comprising a range from 5 μ

m to 8 μ

m;

(d) interposing a transparent support element for scattering light between said polymer dispersion type liquid crystal layers; and

(e) forming a thickness for said transport support element for scattering light comprising a range from 10 μ

m to 10 mm.

10. A method of forming a polymer dispersion type liquid crystal display element of claim 6, wherein the material of said transparent support element for scattering light comprises a transparent substrate combining a plurality of transparent substrates differing in refractive index sequentially from one transparent substrate having the smallest refractive index to another transparent substrate having the largest refractive index and a microlens having a light diffusion effect.

11. A method of forming a reflection type liquid crystal display device, comprising the steps of:

(a) overlaying and disposing a first polymer dispersion type liquid crystal layer dispersing liquid crystal drops in a polymer for controlling the light scatter and transmission electrically;

(b) forming a thickness of said first polymer dispersion type liquid crystal layer comprising a range from 5 μ

m to 18 μ

m;

(c) overlaying and disposing a second polymer dispersion type liquid crystal layer dispersing liquid crystal drops containing dichroic dye in a polymer for controlling the coloring and light transmission electrically;

(d) forming a thickness of said second polymer dispersion type liquid crystal layer comprising a range from 5 μ

m to 18 μ

m;

(e) interposing a transparent support element for scattering light between said first and second polymer dispersion type liquid crystal layers;

(f) forming a thickness of said transparent support element for scattering light comprising a range from 10 μ

m to 10 mm; and

(g) disposing a white reflector plate on the back side of said first or second polymer dispersion type liquid crystal layer.