Process of producing multicolor optical element

• US 20030025858A1
• Filed: 07/01/2002
• Published: 02/06/2003
• Est. Priority Date: 07/05/2001
• Status: Active Grant

• Current Assignee: Dai Nippon Printing Company Limited
• Original Assignee: Dai Nippon Printing Company Limited
• Inventors: Itoh, Norihito
• Granted Patent: US 6,836,307 B2
• Time in Patent Office: Days
• US Class Current: 349/106
• CPC Class Codes: G02B 5/201 in the form of arrays
• CPC Class Codes: G02F 1/133516 Methods for their manufacture, e.g. printing, electro-deposition or photolithography

Abstract

A cholesteric liquid crystal coating film 13′ is formed on an alignment layer 12 provided on a glass substrate 11 (FIG. 1(a)), and is subjected to a thermal alignment process at a temperature equal to or higher than the liquid crystalline phase transition temperature of a chiral nematic liquid crystal that constitutes the coating film (FIG. 1(b)). Active rays capable of activating optically active groups in the chiral nematic liquid crystal are applied to the cholesteric liquid crystal coating film 13′ to deactivate the optically active groups, thereby forming a cholesteric layer 13 having color-indicating regions with the desired areas and indication colors that have been created according to the active-rays-applied area and to the amount of active rays applied to the area (FIG. 1(c)). Thereafter, this cholesteric layer 13 is subjected to a thermal alignment process at a temperature lower than the liquid crystalline phase transition temperature of the chiral nematic liquid crystal (FIG. 1(d)). Lastly, a predetermined amount of ultraviolet light was applied to the cholesteric layer 13 in an atmosphere in which the optically active groups are inactive, thereby three-dimensionally crosslinking the cholesteric layer 13 for curing (FIG. 1(e)).

Claims

1. A process of producing a multi color optical element, comprising the steps of:

preparing a liquid crystal layer comprising a liquid crystal having a cholesteric regularity, the liquid crystal containing, as its constituents, monomers having optically active groups;

applying an active ray to the liquid crystal layer to deactivate the optically active groups, thereby forming a cholesteric layer having color-indicating regions with desired areas and indication colors that have been created according to an applied area of the active ray and to an amount of active ray applied to the area;

subjecting the cholesteric layer having the color-indicating regions to a thermal alignment process at a temperature lower than a liquid crystalline phase transition temperature of the liquid crystal; and

three-dimensionally crosslinking and curing the cholesteric layer subjected to the thermal alignment process.

2. The process according to claim 1, further comprising, before the step of applying the active ray to the liquid crystal layer, the step of subjecting the liquid crystal layer to a thermal alignment process at a temperature equal to or higher than the liquid crystalline phase transition temperature of the liquid crystal.

3. The process according to claim 1, wherein the cholesteric layer having the color-indicating regions is formed by applying an active ray to the liquid crystal layer through a photomask including regions that have different transmittances and areas corresponding to the color-indicating regions to be created.

4. The process according to claim 1, wherein the active ray is an ultraviolet ray.

5. The process according to claim 1, wherein the liquid crystal constituting the cholesteric layer is a chiral nematic liquid crystal, and the cholesteric layer subjected to the thermal alignment process is three-dimensionally crosslinked and cured by application of an ultraviolet ray or an electron beam.

6. A process of producing a multicolor optical element, comprising the steps of:

preparing a liquid crystal layer comprising a liquid crystal having a cholesteric regularity, the liquid crystal containing, as its constituents, monomers having optically active groups;

applying an active ray to the liquid crystal layer to deactivate the optically active groups, thereby forming a cholesteric layer having color-indicating regions with desired areas and indication colors that have been created according to an applied area of the active ray and to an amount of active ray applied to the area;

partially three-dimensionally crosslinking and curing the cholesteric layer having the color-indicating regions;

subjecting the partially three-dimensionally crosslinked cholesteric layer to a thermal alignment process at a temperature equal to or higher than a liquid crystalline phase transition temperature of the liquid crystal; and

three-dimensionally crosslinking and curing the cholesteric layer subjected to the thermal alignment process.

7. The process according to claim 6, further comprising, before the step of applying the active ray to the liquid crystal layer, the step of subjecting the liquid crystal layer to a thermal alignment process at a temperature equal to or higher than the liquid crystalline phase transition temperature of the liquid crystal.

8. The process according to claim 6, wherein the cholesteric layer having the color-indicating regions is formed by applying an active ray to the liquid crystal layer through a photomask including regions that have different transmittances and areas corresponding to the color-indicating regions to be created.

9. The process according to claim 6, wherein the active ray is an ultraviolet ray.

10. The process according to claim 6, wherein the liquid crystal constituting the cholesteric layer is a chiral nematic liquid crystal, and the cholesteric layer subjected to the thermal alignment process is three-dimensionally crosslinked and cured by application of an ultraviolet ray or an electron beam.