Light modulating device with polarizer and liquid crystal interspersed as spherical or randomly distorted droplets in isotropic polymer

• US 5,264,950 A
• Filed: 01/06/1992
• Issued: 11/23/1993
• Est. Priority Date: 01/06/1992
• Status: Expired due to Term

• Current Assignee: Kent State University
• Original Assignee: Kent State University
• Inventors: West, John, Carrell, J. Craig
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/818,720
• Time in Patent Office: 687 Days
• Field of Search: 359/51, 359/52, 359/63
• US Class Current: 349/87
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133531 characterised by the arrangement of polariser or analyser axes

Abstract

The invention provides an improvement in light modulating devices employing birefringent liquid crystal interspersed in isotropic polymer. A polarizer disposed on a surface of the liquid crystal device produces haze-free viewing for all viewing angles in the plane orthogonal to the polarization direction of the light passed by the polarizer.

Claims

1. A light modulating device comprising:

a) a film formed of a birefringent liquid crystal interspersed as spherical or randomly distorted droplets in isotropic polymer, and

b) a polarizer which is effective to absorb one direction of polarization and thereby provide haze-free viewing through the material at all angles in a plane orthogonal to the direction of polarization passed by the polarizer.

2. A light modulating device as claimed in claim 1, wherein said device has an incident surface and a transmitting surface and said polarizer is disposed on said incident surface.

3. A light modulating device as claimed in claim 1 including a second polarizer having a polarization direction parallel to that of said first mentioned polarizer, said film being interposed between said polarizers.

4. In a light modulating device including a light modulating material formed of a birefringent liquid crystal interspersed as spherical or randomly distorted droplets in isotropic polymer having matched indices of refraction and electrodes for establishing a field through said material, the improvement comprising a polarizer which is effective to absorb one direction of polarization of light and thereby produce haze-free viewing at all angles in a plane of view orthogonal to the direction of polarization passed by the polarizer.

5. The improvement according to claim 4, wherein said light modulating device has an incident surface and a transmitting surface and said polarizer is disposed on said incident surface.

6. The improvement according to claim 4 further comprising a second polarizer having a polarization direction parallel to that of said first mentioned polarizer, said film being interposed between said polarizers.

7. In a light modulating liquid crystal device including a birefringent liquid crystal interspersed as spherical or randomly distorted droplets in isotropic polymer, wherein the ordinary index of refraction of the liquid crystal is matched to the index of refraction of the polymer, said device having an incident surface and a transmitting surface, the improvement comprising a polarizer disposed at said incident surface to provide haze-free viewing at all angles in a plane of view orthogonal to the direction of polarization of light passed by said polarizer.

8. A method of providing haze-free viewing at all angles in a selected plane of view from a light modulating material formed of a birefringent liquid crystal interspersed as spherical or randomly distorted droplets in isotropic polymer, comprising disposing a polarizer which is effective to absorb one direction of polarization adjacent a surface of said material and arranging said polarizer so that said direction of polarization is orthogonal to the plain of view selected to be haze-free.

9. The method according to claim 8 further comprising disposing said polarizer adjacent an incident surface of said material.

10. The method according to claim 9 further comprising disposing a second polarizer effective to absorb one polarization direction on an a surface of said material opposite said first mentioned polarizer and arranging said second polarizer to be parallel to said first mentioned polarizer.