LIQUID CRYSTAL WINDOW AND OPTICAL ELEMENT COMPRISING IT

Abstract

The present invention relates to a liquid crystal window, a method of manufacturing the same, an optical element comprising the liquid crystal window, and a use thereof. The liquid crystal window of the present invention and its manufacturing method have excellent fixing property of a spacer and thus excellent cell gap maintaining characteristics, and can effectively prevent thermal damage of a base layer and be economical in manufacturing processes.

Claims

1. A liquid crystal window for an optical element comprising a liquid crystal layer containing a liquid crystal compound; alignment films which are positioned on both sides of said liquid crystal layer and induce orientation of said liquid crystal compound; and spacers formed so as to be capable of maintaining gaps of layers existing in the upper and lower portions of said liquid crystal layer, and embedded in and fixed to any one of the alignment films positioned on both sides of said liquid crystal layer.

2. The liquid crystal window for an optical element according to claim 1, wherein the liquid crystal compound is a smectic, nematic or cholesteric liquid crystal compound, the liquid crystal layer further comprises an anisotropic dye having a dichroic ratio in a range of 1 to 30, and the liquid crystal layer has a thickness in a range of 5 to 30 m.

3. The liquid crystal window for an optical element according to claim 1, further comprising a base layer positioned in one side or both side directions of the liquid crystal layer; and an electrode layer formed on the base layer.

4. The liquid crystal window for an optical element according to claim 1, wherein the alignment film is a coating layer of a composition comprising an orientable compound and spacers, and the spacer is contained in the composition in a range of 0.1 to 5% by weight.

5. The liquid crystal window for an optical element according to claim 1, wherein the spacer is a ball type spacer and the spacer has a diameter in a range of 1 to 100 m.

6. The liquid crystal window for an optical element according to claim 1, wherein the spacer comprises any one selected from the group consisting of a thermosetting or ultraviolet curable resin; glass fiber; and silica.

7. The liquid crystal window for an optical element according to claim 1, wherein the spacer is a white or black spacer.

8. The liquid crystal window for an optical element according to claim 1, wherein the spacer is partially embedded in the alignment film and the penetration depth of the spacer in the alignment film is 0.1 to 50% as compared with the diameter of the spacer.

9. An optical element comprising a first substrate; a first polarizing layer positioned on said first substrate; and the liquid crystal window of claim 1 positioned on said first polarizing layer.

10. The optical element according to claim 9, switching between a transmissive mode in which a transmittance of the visible light region is 15% or more and a blocking mode in which a transmittance of the visible light region is 3% or less, depending on whether or not external action is applied.

11. The optical element according to claim 9, wherein the liquid crystal window further comprises a base layer positioned in one side or both side directions of the liquid crystal layer, the first polarizing layer is attached to the liquid crystal window via a pressure-sensitive adhesive layer or an adhesive layer, and the pressure-sensitive adhesive layer is a fluid pressure-sensitive adhesive layer having a freezing point of 40 C. or lower and a boiling point of 150 C. or higher.

12. The optical element according to claim 9, wherein the liquid crystal window further comprises a base layer positioned only in any one side direction of the liquid crystal layer and the first polarizing layer is in direct contact with the liquid crystal window.

13. The optical element according to claim 9, wherein the first polarizing layer is in direct contact with the first substrate, or is attached to the first substrate via a pressure-sensitive adhesive layer or an adhesive layer.

14. The optical element according to claim 9, wherein any one surface of the first polarizing layer is in direct contact with the first substrate and the other surface is in direct contact with the liquid crystal window.

15. The optical element according to claim 9, further comprising a second substrate positioned on the liquid crystal window.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0199] FIG. 1 is a diagram showing a structure in which spacers in a liquid crystal window of the present invention are embedded in an alignment film.

[0200] FIGS. 2 to 4 are each one illustrative diagram showing an optical element according to the present invention.

[0201] FIG. 5 shows SEM cross-sectional photographs and orientation states of spacers in liquid crystal windows according to Examples and Comparative Examples.

[0202] FIG. 6 shows the lamination test results for the liquid crystal windows according to Examples and Comparative Examples.

MODE FOR INVENTION

[0203] Hereinafter, the present invention will be described in more detail by way of examples, but they are only examples limited to the gist of the present invention. Furthermore, it is apparent to those skilled in the art that the present invention is not limited to the process conditions set forth in the following examples and the conditions may be optionally selected within the range of conditions necessary for achieving the object of the present invention.

Example 1

[0204] A composition for forming an alignment film containing 1 wt % of spacers was coated on a polycarbonate film, on which an ITO electrode layer having a size of 100100 mm was formed, using a Meyer bar (#4), and then dried in an oven at 80 C. for 2 minutes and irradiated with polarized UV to form an alignment film. Thereafter, 1 g of liquid crystal (MDA-14-4145) was coated thereon to form a liquid crystal layer/alignment film/ITO electrode layer/polycarbonate film structure. Finally, the alignment film surface of the polycarbonate film on which the alignment film/ITO electrode layer were sequentially formed, and the surface of the liquid crystal layer were laminated together to manufacture a liquid crystal window.

[0205] As shown in FIG. 5, it can be confirmed that the spacer according to Example 1 is partly embedded in the alignment film to be included in a fixed state.

Comparative Example 1

[0206] An isopropyl alcohol solution containing 1 wt % of spacers was coated on a polycarbonate film, on which an alignment film/an ITO electrode layer having a size of 100 mm100 mm were sequentially formed, using a Meyer bar (#4), and then dried and fixed in an oven at 120 C. for 10 minutes to form spacers fixed on the alignment film. Thereafter, 1 g of liquid crystal (MDA-14-4145) was coated on the surface of the alignment film on which the spacers were formed to form a liquid crystal layer/alignment film/ITO electrode layer/polycarbonate film structure. Finally, the alignment film surface of the polycarbonate film on which the alignment film/ITO electrode layer were sequentially formed, and the surface of the liquid crystal layer were laminated together to manufacture a liquid crystal window.

[0207] As shown in FIG. 5, it can be confirmed that the spacer according to Comparative Example 1 is fixed on the alignment film.

Test Example 1: Lamination Test

[0208] A lamination test of the liquid crystal windows according to Example 1 and Comparative Example 1 was carried out.

[0209] Specifically, the lamination test was performed in such a manner that the manufactured liquid crystal window was passed between upper/lower rubber rolls to apply pressure, and the result was shown in FIG. 6.

[0210] As shown in FIG. 6, the spacer according to Example 1 was embedded in the alignment film to have excellent fixation with being in a state of little change, but the spacer according to Comparative Example 1 was fixed on the alignment film to have a low fixation degree enough to visually confirm black dots. Accordingly, it could be confirmed that the liquid crystal window of the present invention is excellent in terms of the fixing property of the spacer.