Diffusion sheet, laminated prism sheet, and laminated optical sheet

Abstract

Provided is a diffusion sheet having a function for preventing warping, and having excellent optical and diffusion characteristics. A diffusion sheet 1 has a minute roughness pattern formed on the surface thereof, the pattern configured such that first protrusions 3 a having a first height and second protrusions 3 b having a second height lower than the first height are disposed in parallel. A portion of the first protrusions 3 a is bonded to a bonding layer on the rear surface of an upper-layer sheet laminated on the surface of a diffusion sheet 2 , and the second protrusions 3 b are not bonded to said bonding layer. The following relationships are satisfied: h 1 :h 2 =1: 0.5-0.1, and w 1 :w 2 =1:1.0-0.1, where h 1 is the height of the first protrusions 3 a , w 1 is the width of the first protrusions 3 a , h 2 is the height of the second protrusions 3 b , and w 2 is the width of the second protrusions 3 b.

1 - 8 . (canceled) 
     
     
         9 . A laminated prism sheet, comprising:
 at least 2 layer prism sheet having a prism column of a plural number of unit prism of quasi triangle pole being disposed in parallel;   a prism column of a lower layer prism sheet to be laminated to an upper layer prism with a plural number of first prism column having a first height and a plural number of a second prism column having a second height higher than the first height being disposed periodically;   said upper layer prism sheet being furnished by a diffusion layer having a minute convex-concave shape at the back surface thereof;   a vertex portion of said first prism column of said lower layer prism sheet being adhered to an adherence layer laminated on the diffusion layer on the back surface of said upper layer prism sheet, and a vertex portion of said second prism column being not adhered.   
     
     
         10 . A laminated prism sheet as set forth in  claim 9 , further comprising:
 at least one second prism column being disposed in an interim of adjacent first prism columns.   
     
     
         11 . A laminated prism sheet as set forth in  claim 9 , further comprising:
 at least one second prism column being disposed in an interim of first prism column group wherein only a plural number of first prism columns adjacent to each other.   
     
     
         12 . A laminated prism sheet as set forth in  claim 9 , wherein:
 a refractive index of said adhesion layer n b  and a refractive index of said diffusion layer n m  satisfying |n b −n m |>0.1.   
     
     
         13 . A laminated prism sheet as set forth in  claim 9 , wherein:
 a second height of said second prism column being 0.6˜0.9 assuming that a first height of said first prism column being 1.   
     
     
         14 . A laminated prism sheet as set forth in  claim 9 , wherein
 assuming a height of said first prism column to be m 1  and width to be k 1  and further a height of said second column to be m 2  and width to be k 2 , a relationships m 1 :m 2 =1:x (x being 0.6˜0.9) and k 1 :k 2 =1:1 being satisfied.   
     
     
         15 . A laminated prism sheet as set forth in  claim 9 , wherein:
 a shape of a said first prism column forming a shape similar to a shape of said second prism column.   
     
     
         16 - 17 . (canceled) 
     
     
         18 . A laminated prism sheet as set forth in  claim 9 , further comprising:
 a shape of a vertex portion of unit prism of a prism column at said lower layer prism sheet being a curved surface,   said vertex portion of a prism column of said lower layer prism sheet being in contact with a surface of said adhesion layer at a back surface of a prism sheet, preventing penetration.   
     
     
         19 . A prism sheet as set forth in  claim 9 , being laminated on a diffusion sheet and forming at least a portion of a laminated optical sheet. 
     
     
         20 . (canceled) 
     
     
         21 . A laminated optical sheet as set forth in  claim 19 , wherein:
 said prism sheet being a prism sheet for transmitting a P wave and reflecting S wave.   
     
     
         22 . A laminated prism sheet as set forth in  claim 9 , wherein:
 a thickness of said adhesion layer being 0.5˜5 μm.   
     
     
         23 . A diffusion sheet in the laminated optical sheet as set forth in  claim 19 , comprising:
 a first convex portion having a first height being disposed in parallel;   a second convex portion having a random height lower than the height of the first height being disposed periodically or randomly;   having a minute concave and convex configuration at a surface thereof.   
     
     
         24 . A diffusion sheet as set forth in  claim 23 , further comprising;
 a part of a first convex portion being adhered to an adherence layer at a back surface of said upper layer sheet to be laminated to a surface of said diffusion sheet;   a second convex portion being not adhered.   
     
     
         25 . A diffusion sheet as set forth in  claim 23 , wherein:
 a height difference between a height of a first convex portion and a height of a second convex portion being larger than a thickness of said adherence layer.   
     
     
         26 . A diffusion sheet as set forth in  claim 23 , wherein:
 considering a height being h 1  and a width being w 1  for a first convex portion, and a height being h 2  and a width being w 2  for a second convex portion, h 1 :h 2 =1:X (x being 0.5˜0.1) and w 1 :w 2 =1:y (y being 1.0˜0.1) being satisfied.   
     
     
         27 . A diffusion sheet as set forth in  claim 23 , wherein:
 at least one second convex portion being disposed between neighboring first convex portions.   
     
     
         28 . A diffusion sheet as set forth in  claim 23 , further comprising:
 at least one second convex portion being disposed among a first convex portion group consisting of only a first convex portion being neighboring in a plural number.   
     
     
         29 . A diffusion sheet as set forth in  claim 23 , wherein:
 said first convex portion being linear.   
     
     
         30 . A diffusion sheet as set forth in  claim 23 , wherein:
 light diffusive particles being not included in said diffusion sheet.   
     
     
         31 . A diffusion sheet as set forth in  claim 23 , further comprising:
 an interval of neighboring first convex portion being 0.1˜0.6 mm;   an air layer having thickness of 1˜100 μm being disposed between said adhesion layer and a second convex portion at a back surface of said upper layer sheet laminated to a surface of said diffusion sheet.