Light control film with turning film and lenticular diffuser for view enhancement in the horizontal plane

Abstract

Optical system including a lightguide; a turning film, including a first smooth surface perpendicular to a display axis and a first structured surface including a plurality of first microstructures defining a first plurality of parallel grooves, where the turning film is optically coupled to the lightguide, where the turning film outputs light collimated in a first plane parallel to the display axis; and a lenticular diffuser, including a second smooth surface perpendicular to the display axis and a second structured surface comprising a plurality of second microstructures defining a second plurality of parallel grooves extending along a plane perpendicular to the display axis, where the lenticular diffuser is optically coupled to the turning film, where the lenticular diffuser reflects or refracts collimated light toward a second plane perpendicular to the first plane; where the first plurality of parallel grooves is perpendicular to the second plurality of parallel grooves.

We claim: 
     
         1 . An optical system, comprising:
 a liquid crystal display,   a backlight light guide,   a light control film disposed between the backlight light guide and the liquid crystal display, the light control film comprising:   a turning film, comprising:
 a first substantially smooth surface substantially perpendicular to a display axis; and 
 a first structured surface comprising a plurality of first microstructures defining a first plurality of substantially parallel grooves, 
 wherein the turning film outputs light substantially collimated in a first plane; and 
   a lenticular diffuser, comprising:
 a second substantially smooth surface substantially perpendicular to the display axis; and 
 a second structured surface comprising a plurality of second microstructures each comprising a hybrid lenticular prism, wherein a cross section of each hybrid lenticular prism extends along a plane substantially parallel to the display axis in a direction from the second substantially smooth surface to a vertex, wherein the plurality of second microstructures defines a second plurality of substantially parallel grooves on the second structured surface extending along a plane substantially perpendicular to the display axis; and 
 a first material having a first refractive index, wherein the first material forms the plurality of second microstructures, 
 wherein the lenticular diffuser is optically coupled to the turning film and the liquid crystal display; 
   wherein the first plurality of substantially parallel grooves is substantially perpendicular to the second plurality of substantially parallel grooves.   
     
     
         2 . An optical system mounted in a vehicle, comprising:
 a vehicle; and   a display system mounted in the vehicle, the display system comprising:
 a liquid crystal display; 
 a backlight light guide; 
 a turning film, comprising:
 a first substantially smooth surface substantially perpendicular to a display axis; and 
 a first structured surface comprising a plurality of first microstructures defining a first plurality of substantially parallel grooves, 
 wherein the turning film is adjacent to the backlight light guide, wherein the turning film outputs light substantially collimated in a first plane; and 
 
   a lenticular diffuser, comprising:
 a second substantially smooth surface substantially perpendicular to the display axis; and 
 a second structured surface comprising a plurality of second microstructures each comprising a hybrid lenticular prism, wherein a cross section of each hybrid lenticular prism extends along a plane substantially parallel to the display axis in a direction from the second substantially smooth surface to a vertex, wherein the plurality of second microstructures defines a second plurality of substantially parallel grooves on the second structured surface extending along a plane substantially perpendicular to the display axis; and 
 a first material having a first refractive index, wherein the first material forms the plurality of second microstructures, 
 wherein the lenticular diffuser is optically coupled to the turning film and the liquid crystal display; 
 wherein the first plurality of substantially parallel grooves is substantially perpendicular to the second plurality of substantially parallel grooves. 
   
     
     
         3 . An optical system, comprising:
 (a) a turning film, comprising:
 a first substantially smooth surface substantially perpendicular to a display axis; and 
 a first structured surface comprising a plurality of first microstructures defining a first plurality of substantially parallel grooves, 
 wherein the turning film outputs light substantially collimated in a first plane; and 
   (b) a lenticular diffuser, comprising:
 a second substantially smooth surface substantially perpendicular to the display axis; and 
 a second structured surface comprising a plurality of lenticular prisms defining a second plurality of substantially parallel grooves extending along a plane substantially perpendicular the display axis, 
 wherein the second structured surface comprising a plurality of lenticular prisms comprises a plurality of two-sided substantially straight-facet prisms having rounded tips separated by a substantially flat land area, 
 wherein a cross section of each lenticular prism extends along a plane substantially parallel to the display axis in a direction from the second substantially smooth surface to a vertex, 
 wherein the lenticular diffuser is optically coupled to the turning film, and wherein the lenticular diffuser reflects or refracts light substantially collimated in the first plane toward a second plane substantially perpendicular to the first plane; 
   wherein the first plurality of substantially parallel grooves is substantially perpendicular to the second plurality of substantially parallel grooves.   
     
     
         4 . The optical system of  claim 3 , wherein the lenticular diffuser further comprises a first material having a first refractive index and a second material having a second refractive index, wherein the first material forms the plurality of lenticular prisms, the second material is adjacent the first material and the first refractive index is greater than the second refractive index. 
     
     
         5 . The optical system of  claim 4 , wherein the difference between the first refractive index and the second refractive index is between about 0.05 and about 0.6. 
     
     
         6 . The optical system of  claim 5 , wherein the difference between the first refractive index and the second refractive index is between about 0.1 and about 0.3. 
     
     
         7 . The optical system of  claim 6 , wherein the difference between the first refractive index and the second refractive index is between about 0.15 and about 0.25. 
     
     
         8 . The optical system of  claim 3 , wherein the lenticular prisms have a pitch (p) and a land width (w) and the second structured surface has a fill fraction of about 0.6 to about 0.95, wherein the fill fraction equals (p−w)/p. 
     
     
         9 . The optical system of  claim 8  wherein the second structure surface has a fill fraction of about 0.8 to about 0.9. 
     
     
         10 . The optical system of  claim 3 , wherein the lenticular prisms have sidewall base angles (α 1  and α 2 ) of about 75 degrees to about 80 degrees. 
     
     
         11 . The optical system of  claim 10 , wherein the lenticular prisms have sidewall base angles of about 77 degrees to about 79 degrees. 
     
     
         12 . The optical system of  claim 3 , wherein the lenticular prisms have a tip radius (R tip ) of about 2 μm or less. 
     
     
         13 . The optical system of  claim 12 , wherein the lenticular prisms have a tip radius of about 1 μm or less. 
     
     
         14 . The optical system of  claim 3 , wherein the lenticular prisms have a tip fraction of less than about 0.1, wherein the tip fraction equals R tip /p. 
     
     
         15 . The optical system of  claim 14 , wherein the lenticular prisms have a tip fraction of less than about 0.035. 
     
     
         16 . The optical system of  claim 3 , wherein the aspect ratio is about 1.8 to about 2.5. 
     
     
         17 . The optical system of  claim 3 , wherein the first substantially smooth surface is adjacent the second substantially smooth surface. 
     
     
         18 . The optical system of  claim 3 , wherein the first substantially smooth surface is adjacent the second structured surface. 
     
     
         19 . The optical system of  claim 3 , wherein the lenticular diffuser is configured to provide greater than about ±40 degrees half width at half maximum (HWHM) luminance from an input light beam less than about ±30 degrees HWHM. 
     
     
         20 . The optical system of  claim 3 , wherein the lenticular diffuser is configured to provide greater than about ±50 degrees half width at half maximum (HWHM) luminance from an input light beam less than about ±20 degrees HWHM. 
     
     
         21 . The optical system of  claim 3 , further comprising a backlight light guide adjacent to the turning film, wherein the backlight light guide outputs substantially collimated light. 
     
     
         22 . A liquid crystal display system, comprising:
 (a) a liquid crystal display,   (b) a backlight guide, and   (c) a light control film disposed between the backlight light guide and the liquid crystal display, the light control film comprising the optical system of  claim 3 .   
     
     
         23 . An optical system mounted in a vehicle, comprising:
 (a) a vehicle; and   (b) a liquid crystal display system of  claim 22  mounted in the vehicle.