Curved Automatic-Darkening Filter

EXAMPLE

Liquid Crystal Cell Assembly

[0047]A curved liquid crystal cell for an automatic welding filter was made in the following manner.

[0048]The starting flexible glass layer was a 0.1 mm thick D263T glass from Schott Glass of Schott Glas Export, GmbH, located at Rheinallee 145, 55120 Mainz, Germany. The glass was sputter deposited with indium tin oxide (ITO). The conductivity of the coated ITO was roughly 100 ohm/square. The ITO glass was coated with a thin layer of polymide polymer. A commercially-available polyimide alignment material was coated onto the glass using a spin coating technique. The dried coating thickness was between 80 nanometers (nm) and 200 nm. The thin polymide layer was aligned by brushing it with using a rotating felt cloth. This brushed polymide, ITO/glass piece was cut into pieces for the top and bottom portion of the liquid crystal cell. A first piece (top) of glass was rotated 90° from the orientation of the second (bottom) piece of glass to provide proper alignment.

[0049]The curved, liquid-crystal cell was formed using a metal cylinder that had a radius of approximately 90 millimeters (mm) as the template. The bottom portion of the cell, the ITO glass having the rubbed polyimide coating, was taped to the metal cylinder using 3M Magic Tape™. An edge adhesive (UV curing Norland 68 optical adhesive) was applied to the bottom portion using a syringe and needle. A twisted, nematic, liquid-crystal mixture was combined with 1% by weight of 4 micrometer (μm) ceramic spacer beads. The liquid crystal/spacer bead mixture was placed on the bottom portion of the cell using a pipette. The top portion of the cell was attached to the bottom portion at the leading edge using 3M Removable Tape™. A polyester film, that was attached to the metal cylinder on one end, was used to wrap and curve the top portion of the cell onto the bottom portion. A rubber roll was used to compress the top portion onto the bottom portion. Tension was maintained on the polyester film to keep the components of the cell in close contact. Using a UV light source for 5 minutes, the UV curing edge adhesive was then cured. The completed cell was then removed from the cylinder by removing the polyester film and pieces of tape. Polarizing films were attached to the bottom and top portions using a pressure-sensitive adhesive. The polarizing films were orthogonal to each other and corresponded to the alignment that was rubbed into the polyimide layer. Copper tape, with conductive adhesive, was attached to the ITO on the top portion, and another piece of copper tape with conductive tape was attached to the ITO on the bottom portion. A 10 volt potential was placed across the cell through the copper tape. The cell switched from a light state to a dark state when the voltage was applied. The dimensions of the finished cell were approximately 75 mm wide and 75 mm long (5625 mm2; 56.25 cm2) with a curvature that was slightly less than the 100 mm radius of the original cylinder.

[0050]This invention may take on various modifications and alterations without departing from its spirit and scope. Accordingly, this invention is not limited to the above-described but is to be controlled by the limitations set forth in the following claims and any equivalents thereof.

[0051]This invention also may be suitably practiced in the absence of any element not specifically disclosed herein.

[0052]All patents and patent applications cited above, including those in the Background section, are incorporated by reference into this document in total. To the extent there is a conflict or discrepancy between the disclosure in such incorporated document and the above specification, the above specification will control.