Optical film having microeplicated structures; and methods

Abstract

An optical film for use in transparent displays, such as reflective LCDs. The optical film has three-dimensional, prismatic structures that reflect incoming light. The prismatic structures are configured so that the reflecting facets orient the reflected light in desired reflective light pattern. The pattern shape and intensity can be controlled by the shape and dimensions of the various reflecting facets. In one embodiment, the height of the prismatic structure varies along two dimensions of the structure.

1 - 11 . (Canceled)  
   
   
       12 . A light directing film comprising a structured surface having a plurality of reflective structures, each of the reflective structures having a ridge extending along a longitudinal direction with a height of the structure varying along the longitudinal direction, the reflective structures having a shape that, in combination with the height variation, scatters a collimated beam of incident light such that the intensity of scattered light versus angle over a desired angular width is substantially flat.  
   
   
       13 . A light directing film comprising a structured surface, the structured surface including a plurality of regularly spaced reflective prismatic structures, each reflective prismatic structure having a plurality of nonlinear facets, wherein a collimated light incident on the structured surface is reflected with a light intensity profile having a substantially flat top.  
   
   
       14 . The light directing film of  claim 13 , wherein the plurality of regularly spaced reflective prismatic structures form ridge-like structures.  
   
   
       15 . The light directing film of  claim 13 , wherein the plurality of regularly spaced reflective prismatic structures include three-dimensional reflective prismatic structures.  
   
   
       16 . The light directing film of  claim 13 , wherein a nonlinear facet of each reflective prismatic structure has a discontinuous slope.  
   
   
       17 . The light directing film of  claim 13 , wherein the flat top is rectangular.  
   
   
       18 . The light directing film of  claim 13 , wherein the structured surface includes quasi-random microstructures superimposed on the prismatic structures.  
   
   
       19 . The light directing film of  claim 13 , wherein the structured surface includes random microstructures superimposed on the prismatic structures.  
   
   
       20 . The light directing film of  claim 13 , wherein the plurality of nonlinear facets include curved facets.  
   
   
       21 . The light directing film of  claim 13 , wherein the plurality of nonlinear facets include a nonlinear facet having at least two sections.  
   
   
       22 . The light directing film of  claim 21 , wherein one of the at least two sections is linear.  
   
   
       23 . The light directing film of  claim 13 , wherein the structured surface is microreplicated.  
   
   
       24 . The light directing film of  claim 13  having a diffuser layer.  
   
   
       25 . The light directing film of  claim 13 , wherein each reflective prismatic structure has a discontinuous slope on its surface.  
   
   
       26 . A light directing film comprising a structured surface and having an x-axis and a y-axis, the structured surface having a plurality of reflective prismatic structures along both the x-axis and the y-axis, a cross-section of the plurality of reflective prismatic structures along each of the x-axis and the y-axis having alternating single are and double arc sections.