Spontaneous alignment method for manufacturing cholesteric reflective polarizer

• US 6,721,030 B2
• Filed: 09/10/2002
• Issued: 04/13/2004
• Est. Priority Date: 05/01/2002
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Kuo, Hui-Lung, Hsieh, Pao-Ju, Chu, Wen-Bing, Wu, Ping-Yao
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US10/237,789
• Publication Number:
  US 20030206259A1
• Time in Patent Office: 581 Days
• Field of Search: 349/191, 349/185, 349/187, 349/189
• US Class Current: 349/191
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers

Abstract

To form a brightness enhancement film of cholesteric liquid crystal, a photopolymerizable liquid crystal is first formed on a first substrate. A second substrate then is formed on the liquid crystal substance to form a sandwich structure. The sandwich structure is subsequently submitted to a lamination process that generates shear stress thereon. Finally, an energetic irradiation including UV irradiation is performed to solidify the layer of liquid crystal into a liquid crystal polymer film. The second substrate then is selectively removed. The above steps are repeated until a desired reflected wavelength range of the liquid crystal film is obtained.

Claims

1. A spontaneous alignment method for manufacturing cholesteric reflective polarizer, comprising:

(1) providing a first substrate;

(2) forming a photopolymerizable liquid crystal substance on the first substrate, the photopolymerizable liquid crystal substance being within in a liquid crystal state;

(3) covering the liquid crystal substance with a second substrate, thereby forming a sandwich structure;

(4) performing a lamination process that generates shear stress on the sandwich structure;

(5) solidifying the oriented liquid crystal into a liquid crystal polymer film via energetic irradiation including UV irradiation;

(6) selectively removing the second substrate, the selective removal being performed when step (7) is to be performed, otherwise the second substrate is either removed or kept as desired; and

(7) repeating steps (2)˜

(6) until a desired reflected wavelength range is obtained.

2. The method of claim 1, wherein the first substrate is either a highly transparent film or a compensation film.

3. The method of claim 1, wherein the second substrate is either a compensation film or a film of a same material as the first substrate.

4. The method of claim 1, wherein the liquid crystal substance is formed on the first substrate via slot die or roll coating.

5. The method of claim 1, wherein the liquid crystal substance is a cholesteric liquid crystal phase liquid crystal chemical compound or mixture.

6. The method of claim 1, wherein not all of the photopolymerizable liquid crystal substance is photopolymerizable, and a portion is comprised of oligomer substance.

7. The method of claim 1, wherein the liquid crystal state is within about 10°

C. through 160°

C., maintained via a hot melt treatment.

8. The method of claim 1, wherein the lamination process is achieved via two rollers rotating with counter directions and defining a spacing there between where the sandwich structure is passed through, the spacing between the rollers controlling a thickness of the liquid crystal, wherein the rollers are maintained at a given temperature, thereby ensuring the application of a shear stress on the liquid crystal.