Method of making a variable density light control apparatus by stretching an unsupported film

• US 5,479,277 A
• Filed: 05/11/1992
• Issued: 12/26/1995
• Est. Priority Date: 10/19/1988
• Status: Expired due to Term

• Current Assignee: Fergason Patent Properties
• Original Assignee: James L. Fergason
• Inventors: Fergason, James L.
• Primary Examiner(s): GROSS, ANITA P
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/881,423
• Time in Patent Office: 1,324 Days
• Field of Search: 359/51, 359/52
• US Class Current: 349/86
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: G02C 7/101 having an electro-optical light valve electro-optical elements per se G02F
• CPC Class Codes: G02C 7/12 Polarisers
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence

Abstract

A method of making a liquid crystal polarizer includes casting an emulsion of liquid crystal material with pleochroic dye in a containment medium, and forming elongate volumes of said liquid crystal material and pleochroic dye in said containment medium. A liquid crystal polarizer device includes liquid crystal material having low birefringence, a containment medium for containing said liquid crystal material in elongate volumes, and means in combination with said liquid crystal material for affecting polarization of light incident thereon; the liquid crystal material being responsive to a prescribed input to change the optical polarization characteristic of the device.

Claims

1. A method of making a liquid crystal polarizer comprising casting an emulsion of liquid crystal material with pleochroic dye in a containment medium to form a film, and forming substantially permanent elongate volumes of said liquid crystal material and pleochroic dye in said containment medium by stretching the film while it is unsupported, and wherein said forming step comprises curing said cast material while stretching said cast material.

2. The method of claim 1, wherein said pleochroic dye is generally colorless.

3. The method of claim 1, further comprising selecting such pleochroic dye to be operative to effect polarization of light incident thereon as a function of alignment of such pleochroic dye in such volumes.

4. The method of claim 3, said liquid crystal having an ordinary index of refraction that is substantially the same as the index of refraction of said containment medium, and wherein said liquid crystal material has a relatively low birefringence characteristic.

5. The method of claim 1, wherein said liquid crystal material has positive dielectric anisotropy.

6. The method of claim 1, said stretching comprising stretching the film in a longitudinal direction.

7. A method of making a liquid crystal polarizer comprising casting an emulsion of liquid crystal material with pleochroic dye in a containment medium to form a film, and forming substantially permanent elongate volumes of said liquid crystal material and pleochroic dye in said containment medium by stretching the film while it is unsupported, and wherein the width of said elongate volumes measured in a direction perpendicular to the axis of elongation is approximately 0.5 to 7 microns.

8. The method of claim 7, wherein the length of said elongate volumes along the axis of elongation is approximately two to five times said width.

9. A liquid crystal polarizer comprising liquid crystal material having low birefringence, a containment medium for containing said liquid crystal material in elongate volumes, and means in combination with said liquid crystal material for affecting polarization of light incident thereon, and wherein the width of said elongate volumes measured in a direction perpendicular to the axis of elongation is approximately 0.5 to 7 microns.

10. The polarizer of claim 9, wherein the length of said elongate volumes along the axis of elongation is approximately two to five times said width.

11. A method of making a liquid crystal polarizer comprising casting liquid crystal material in a containment medium to form a film, and forming substantially permanent elongate volumes of said liquid crystal material by stretching the film while it is unsupported said casting comprising casting an emulsion of liquid crystal material, containment medium and pleochroic dye, allowing the emulsion to at least partially cure, and said forming comprising substantially longitudinally stretching the emulsion in a partially cured state to form substantially permanent elongate volumes of said liquid crystal material and pleochroic dye in said containment medium.

12. A method of making a liquid crystal polarizer comprising casting liquid crystal material in a containment medium to form a film, and forming substantially permanent elongate volumes of said liquid crystal material by stretching the film while it is unsupported, allowing the film to at least partially cure, and said forming comprising substantially longitudinally stretching the film while in the partially cured state.

13. The method of claim 12, allowing the film to complete curing to the extent that the volumes are at least substantially permanently maintained elongate.