Optical control devices and methods of making
Herein are disclosed methods by which a layer of oriented chromonic material may be transferred from a flexible substrate to a receiving substrate, so as to form a subassembly for use in the assembly of liquid crystal cells. The oriented chromonic material layer may function as an alignment layer for aligning liquid crystal material, and may also incorporate a pleochroic dye so to function as a polarizing layer. An oriented chromonic material layer of relatively large area can be transferred, which enables the production of relatively large liquid crystal cells for use in, e.g., autodarkening filters such as used for eye protection in welding operations. Curved liquid crystal cells are also disclosed.
1. An optical control device comprising:
an optically clear first substrate comprising at least a curved first major surface;
a conductive layer adjacent the curved first major surface of the first substrate;
an alignment-polarizer layer adjacent the conductive layer,
wherein the alignment-polarizer layer comprises an oriented chromonic material that further comprises at least one pleochroic dye;
an optically clear second substrate comprising at least a curved first major surface,
wherein the curved first major surface of the first substrate, and the curved first major surface of the second substrate, are mated so as to define a cavity therebetween; and,
a liquid crystal material layer between the alignment-polarizer layer and the curved first major surface of the second substrate and the liquid crystal material layer being in contact with the alignment-polarizer layer;
wherein the conductive layer is disposed on the curved first major surface of the first substrate and wherein the alignment-polarizer layer is bonded to the conductive layer by a layer of cured optically clear adhesive therebetween,
and wherein the optically clear first substrate is a glass substrate and wherein the optical control device is a curved autodarkening filter of an eye protection apparatus.
2. The device of claim 1 wherein the optically clear first substrate comprises an oppositely-facing second major surface and wherein the optical control device is a part of the eye protection apparatus that is arranged such that, when the apparatus is worn by a user, the curved first major surface of the first substrate faces inward toward the eyes of the user and the second major surface of the first substrate faces outward away from the eyes of the user.
3. The device of claim 1 wherein the curved first major surface of the first substrate, the conductive layer, and the alignment-polarizer layer, comprise at least a coextensive area of at least 20 cm 2 .
4. The device of claim 3 wherein the curved first major surface of the first substrate is a concave surface comprising a radius of curvature of between 40 and 200 mm.
5. The device of claim 4 wherein the concave first major surface of the first substrate and the curved first major surface of the second substrate are mated so as to provide a cavity therebetween that is generally uniform in thickness over at least 80 percent of the area of the concave first major surface of the first substrate.
6. The device of claim 4 wherein the first substrate comprises differing radii of curvature over the concave first major surface of the first substrate.
7. The device of claim 1 wherein the second substrate comprises an oppositely-facing second major surface and wherein the device further comprises a second conductive layer adjacent the curved first major surface of the second substrate, and an alignment layer adjacent the second conductive layer and in contact with the liquid crystal material layer, and a polarizer layer adjacent the curved first major surface of the second substrate or the oppositely-facing second major surface of the second substrate.
8. The device of claim 7 wherein the alignment layer adjacent the second conductive layer, and the polarizer layer adjacent the curved first major surface of the second substrate or the oppositely-facing second major surface of the second substrate, comprise a single second alignment-polarizing layer that is between the second conductive layer and the liquid crystal material layer and that is in contact with the liquid crystal material layer, and wherein the single second alignment-polarizer layer comprises an oriented chromonic material comprising at least one pleochroic dye.
9. The device of claim 8 further comprising a layer of cured optically clear adhesive between the single second alignment-polarizer layer and the curved first major surface of the second substrate.
10. The device of claim 1 wherein the autodarkening filter comprises an optical pathway that provides a viewing area for a wearer of the eye protection apparatus and wherein the conductive layer, the alignment-polarizer layer, the liquid crystal material layer, and the cured optically clear adhesive layer are all coextensive with each other at least within the viewing area of the autodarkening filter.
11. The device of claim 1 wherein the eye protection apparatus is part of a welding helmet.
12. The device of claim 1 wherein the device further comprises an ultraviolet radiation filter layer.
13. The device of claim 1 wherein the optically clear first substrate is glass sheeting with a thickness of about 1 mm or greater.
14. The device of claim 1 wherein the cured optically clear adhesive is a hard and rigid network with a Shore D hardness of at least about 40.
15. The device of claim 1 wherein the cured optically clear adhesive is not a pressure-sensitive adhesive.