Light directing sheeting and systems employing the same

Abstract

An optically transmissive light directing sheeting and a method of making the same are disclosed. The light directing sheeting includes a core sheet of an elastic material that can be laminated onto other surfaces or sandwiched between sheets of various rigid materials. The core sheet includes a plurality of deep and narrow parallel channels configured to direct light by means of a total internal reflection. The method includes a step of slitting of a soft, optically transmissive plastic sheet with a blade and forming at least one array of substantially parallel linear slits in a surface of the sheet, a step of stretching the sheet in a direction perpendicular to the linear slits, and a step of bonding the sheet to a different sheet of an optically transmissive, rigid material. Various light directing devices employing the light directing sheeting are also disclosed.

What is claimed is: 
     
         1 . Light directing sheeting, comprising:
 a sheet of an optically transmissive and elastic material defined by a first major surface and an opposing second major surface extending parallel to said first major surface, said sheet of an optically transmissive and elastic material comprising a plurality of narrow channels extending between said first and second major surfaces, wherein each of the plurality of narrow channels comprises a first wall and an opposing second wall that are configured to reflect light by means of a total internal reflection.   
     
     
         2 . Light directing sheeting as recited in  claim 1 , wherein the material of said sheet comprises optically clear or translucent plasticized polyvinyl chloride. 
     
     
         3 . Light directing sheeting as recited in  claim 1 , wherein the material of said sheet comprises optically clear or translucent thermoplastic polyurethane. 
     
     
         4 . Light directing sheeting as recited in  claim 1 , wherein the material of said sheet is selected from the group of polymeric materials consisting of optically clear or translucent thermoplastic elastomers, optically clear or translucent polyurethanes, and optically clear or translucent silicones. 
     
     
         5 . Light directing sheeting as recited in  claim 1 , wherein said optically transmissive and elastic material has a durometer hardness below 95 Shore A. 
     
     
         6 . Light directing sheeting as recited in  claim 1 , wherein said optically transmissive and elastic material has an elastic range of at least 10% relatively to its original length. 
     
     
         7 . Light directing sheeting as recited in  claim 1 , wherein said optically transmissive and elastic material has an elastic range of at least 30% relatively to its original length. 
     
     
         8 . Light directing sheeting as recited in  claim 1 , wherein said sheet of an optically transmissive and elastic material is sandwiched between a first sheet of a rigid material and a second sheet of a rigid material. 
     
     
         9 . Light directing sheeting as recited in  claim 6 , wherein the material of at least one of said first and second sheets of a rigid material is selected from the group of optically transmissive materials consisting of glass, poly(methyl methacrylate), polycarbonate, polystyrene, rigid polyvinyl chloride, polyester, and cyclic olefin copolymer. 
     
     
         10 . Light directing sheeting as recited in  claim 6 , further comprising at least one layer of optically clear adhesive for bonding together said sheet of an optically transmissive and elastic material and at least one of said first and second sheets of a rigid material. 
     
     
         11 . Light directing sheeting as recited in  claim 1 , wherein each of the plurality of channels is aligned parallel to a predefined reference line. 
     
     
         12 . Light directing sheeting as recited in  claim 1 , wherein said plurality of narrow channels is formed by a first array of said channels aligned parallel to a first reference line and a second array of said channels aligned parallel to a second reference line, said first and second reference lines being perpendicular to each other. 
     
     
         13 . Light directing sheeting as recited in  claim 1 , wherein said sheet includes a first layer and a second layer, and wherein a first array of the plurality of said channels is formed in said first layer and a second array of the plurality of said channels is formed in said second layer. 
     
     
         14 . Light directing sheeting as recited in  claim 13 , wherein channels of the first array are generally perpendicular to the channels of the second array. 
     
     
         15 . Light directing sheeting as recited in  claim 1 , wherein a root mean square surface profile roughness parameter of each of said walls is at most about 60 nanometers at a sampling length of between 20 and 100 micrometers. 
     
     
         16 . Light directing sheeting as recited in  claim 1 , wherein a root mean square surface profile roughness parameter of at least a substantial portion of the surface of each of said walls is at least about 10 nanometers at a sampling length of between 20 and 100 micrometers. 
     
     
         17 . Light directing sheeting as recited in  claim 1 , wherein the thickness of said intermediate sheet is between 200 micrometers and 2 millimeters. 
     
     
         18 . Light directing sheeting as recited in  claim 1 , wherein at least one edge of said sheet material is made impermeable to moisture and/or air. 
     
     
         19 . Light directing sheeting as recited in  claim 1 , further comprising light diffusing features. 
     
     
         20 . Light directing sheeting as recited in  claim 1 , further comprising surface microstructures.