Packaging and handling method for optical films

Abstract

The invention is directed to a new packaging method in which several optical films are bundled together before insertion into the display frame. This bundling makes handling of the films easier, reduces the number of steps required for assembly of the display device, reduces the chance of damaging the films and increases yields. At least two of the films in the stack are bonded together using a zero-gap bond. The zero-gap bond lies outside the viewing area of the film.

1 . A method for stacking optical films for an optical display, comprising: 
 providing first and second optical films with respective viewing areas; and    bonding the first and second optical films with a zero-gap bond outside viewing areas of the first and second optical films.    
     
     
         2 . A method as recited in  claim 1 , wherein the zero-gap bond is only outside the viewing areas of the first and second optical films.  
     
     
         3 . A method as recited in claim 1 , wherein bonding the first and second optical films includes bonding peripheral tabs on the first and second optical films.  
     
     
         4 . A method as recited in  claim 1 , wherein bonding the first and second optical films includes bonding at least portions of peripheral edges of the first and second optical films.  
     
     
         5 . A method as recited in  claim 1 , further comprising overlapping the first and second optical films, welding the first and second optical films together, and cutting the first and second optical films to a desired size.  
     
     
         6 . A method as recited in  claim 1 , further including stripping first and second liner layers from the respective first and second optical films.  
     
     
         7 . A method as recited in  claim 5 , wherein cutting the first and second optical films includes cutting through the first and second optical films to a depth that leaves a liner layer associated with the second optical film uncut.  
     
     
         8 . A method as recited in  claim 5 , wherein welding the first and second optical films together includes thermally welding the first and second optical films  
     
     
         9 . A method as recited in  claim 5 , wherein thermally welding includes applying heat through radiative heat transfer.  
     
     
         10 . A method as recited in  claim 5 , wherein thermally welding includes applying heat through conductive heat transfer.  
     
     
         11 . A method as recited in  claim 5 , wherein thermally welding includes applying heat through convective heat transfer.  
     
     
         12 . A method as recited in  claim 5 , wherein thermally welding includes generating heat through friction.  
     
     
         13 . A method as recited in  claim 5 , wherein cutting the first and second optical films includes passing the first and second optical films through a die roller.  
     
     
         14 . A method as recited in  claim 5 , wherein the first optical film is a prismatic film having prismatic ribs in a first orientation and the second optical film is a prismatic film having prismatic ribs in a second orientation non-parallel to the first orientation.  
     
     
         15 . A method as recited in  claim 1 , wherein providing the first and second optical films includes pulling at least one of the first and second optical films off a roll containing the at least one of the first and second optical films.  
     
     
         16 . A method as recited in  claim 1 , wherein providing the first and second optical films includes disposing at least one of the first and second optical films out of a sheet feeder that contains individual sheets of the at least one and second optical films.  
     
     
         17 . A method as recited in  claim 1 , wherein providing the first and second optical films includes providing at least a third optical film and further comprising bonding the at least a third optical film to one of the first and second optical films.  
     
     
         18 . A method as recited in  claim 1 , further comprising stacking at least two optical film sheets, bonding the two or more optical film sheets and then cutting the bonded film sheets into film stacks.  
     
     
         19 . A method as recited in  claim 1 , wherein at least one of the first and second optical films includes a prismatic structure on at least one surface.  
     
     
         20 . A light management film package for managing light within a display, comprising: 
 a first optical film having a first surface; and    a second optical film disposed over the first optical film, the second optical film having a first surface bonded to the first surface of the first optical film at a zero-gap film bond, a center viewing portion of the second optical film remaining unbonded to the first optical film.    
     
     
         21 . A film package as recited in  claim 20 , wherein the first and second optical films each have at least one respective peripheral tab outside the respective viewing areas, the at least one peripheral tabs of the first and second optical films being in registration and bonded together to form the zero-gap film bond.  
     
     
         22 . A film package as recited in  claim 20 , further comprising a third optical film bonded to the second optical film via a zero-gap bond.  
     
     
         23 . A film package as recited in  claim 22 , wherein the first and second optical films are prismatic, light directing films, and the third optical film is a reflecting polarizer.  
     
     
         24 . A film package as recited in  claim 20 , wherein the first and second optical films each have respective peripheral edges in registration, at least a portion of at least one peripheral edge of the first optical film being bonded together with at least one peripheral edge of the second optical film to form the zero-gap bond.  
     
     
         25 . A film package as recited in  claim 20 , wherein the zero-gap bond is a thermal bond between the first and second optical films.  
     
     
         26 . A film package as recited in  claim 26 , wherein the thermal bond is an ultrasonic bond.  
     
     
         27 . A film package as recited in  claim 26 , wherein the thermal bond is a laser-welded bond.  
     
     
         28 . A film package as recited in  claim 26 , wherein the thermal bond is formed by a hot press.  
     
     
         29 . A film package as recited in  claim 20 , wherein the zero-gap bond is a chemical bond between the first and second optical films.  
     
     
         30 . A film package as recited in  claim 20 , wherein the zero-gap bond is a mechanical bond between the first and second optical films.  
     
     
         31 . A film package as recited in  claim 20 , wherein the first optical film is a prismatic, light directing film having a prismatically structured surface oriented towards the second optical film.  
     
     
         32 . A film package as recited in  claim 31 , wherein the second optical film is a prismatic, light directing film having a substantially flat surface oriented towards the first optical film and a prismatically structured surface with ribs oriented substantially perpendicular to ribs of the prismatically structured surface of the first optical film.  
     
     
         33 . A film package as recited in  claim 20 , further comprising a display element, the stack of at least first and second optical films being attached to the display element.  
     
     
         34 . A film package as recited in  claim 20 , further comprising a backlight unit, the stack of at least first and second optical films being attached to the backlight unit.  
     
     
         35 . A display system, comprising: 
 an illumination unit;    a display unit; and    a light management unit disposed between the illumination unit and the display unit to manage light passing from the illumination unit to the display unit, the light management unit comprising a stack of at least first and second optical films, the first optical film having a first surface and the second optical film being disposed over the first optical film, the second optical film having a first surface bonded to the first surface of the first optical film at a zero-gap film bond, a center viewing portion of the second optical film remaining unbonded to the first optical film.    
     
     
         36 . A system as recited in  claim 35 , further comprising a control unit coupled to the display unit to control an image displayed by the display unit.  
     
     
         37 . A system as recited in  claim 35 , wherein the display unit includes a liquid crystal display layer.  
     
     
         38 . A system as recited in  claim 37 , further comprising an absorbing polarizer layer on a viewing side of the liquid crystal display layers and an absorbing polarizer on a light source side of the liquid crystal display layer.  
     
     
         39 . A system as recited in  claim 35 , wherein the illumination unit includes one or more light sources illuminating a light guide panel, light from the one or more light sources entering the light guide panel and passing through a surface of the light guide panel to the light management unit.  
     
     
         40 . A system as recited in  claim 35 , further comprising a frame holding the illumination unit, the light management unit and the display unit.  
     
     
         41 . A system as recited in  claim 40 , wherein at least the first and second optical films of the light management unit include one or more peripheral alignment tabs for locating the light management unit within the frame, the one or more peripheral alignment tabs being bonded together to form the zero gap bond.  
     
     
         42 . A light management film package for managing light within a display, comprising: 
 a first optical film having a first surface; and    a second optical film disposed over the first optical film, the second optical film having a first surface bonded to the first surface of the first optical film by a zero-gap bonding means for bonding the first and second optical films together, a center viewing portion of the second optical film remaining unbonded to the first optical film.    
     
     
         43 . A light management film package for managing light within a display, comprising: 
 a stack of at least first and second optical films having respective first and second viewing areas in alignment to form a stack viewing area, zero-gap bond means for bonding films between the first and second optical films being disposed outside the first and second viewing areas.