Abstract:
An optical film delivery unit is comprised of an optical film strip having optical films protected by at least one liner. Scores, typically dot-line cuts, in the liners initiate folding. The optical film strip is folded along the scores such that the optical film delivery unit assumes a Z-fold structure that provides several advantages. There is no tension on the strip. The optical films do not create impressions on each other and remain flat. In addition, the optical film unit is relatively small making it more efficient to package and transport.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to optical films. In particular, the present invention relates to delivery formats of optical films.  
         [0002]     Optical displays, such as backlit liquid crystal displays (LCDs), are used in a wide variety of applications including mobile telephones, personal digital assistants (PDAs), electronic games, laptop computers, monitors and television screens. Optical films are stacked within an optical display in order to enhance brightness and improve display performance without sacrificing battery life.  
         [0003]     Currently, individual optical films are placed between protective layers, which are then wound around a reel. Several issues result from using the reel format for delivery of optical films. First, tension is placed on the strip as it is wound in order to create a tightly wound reel. As a result of the increased tension along with the weight of the material itself, optical films layered adjacent to each other around the reel may leave impressions on each other. In addition, the optical films tend to curl when removed from the protective liners. Resolving these problems would reduce damage to the optical films.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     The present invention is an optical film delivery unit and a method of making the optical film delivery unit. Optical films are on a liner, which is scored and folded such that the optical film delivery unit assumes a Z-fold structure. The Z-fold structure has at least one fold and a plurality of pages. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a front view of a representative embodiment of the optical film delivery unit.  
         [0006]      FIG. 2  is a top view of a representative embodiment of the optical film strip.  
         [0007]      FIG. 3  is a schematic illustration of a representative embodiment of the method of making the optical film delivery unit. 
     
    
     DETAILED DESCRIPTION  
       [0008]      FIG. 1  shows a representative embodiment of optical film delivery unit  10 . Unit  10  includes optical film strip  12  with liner  14 , optical films  16 , which may be light directing films, diffuser-type films, turning films, multi-layer polymer films, reflective films, etc. and liner  18 . Liner  14  includes folds  14   a , and liner  18  includes folds  18   a . Optical films  16  are placed between liners  14  and  18 . Liners  14  and  18  fold at folds  14   a  and  18   a , respectively, such that unit  10  forms a Z-fold (accordion fold, zig-zag fold) structure.  
         [0009]     Liners  14  and  18  are protective coverings for films  16  and may be composed of identical or different materials. Optical films  16  are held between liners  14  and  18  by any of a number of ways, such as, for example, adhesive tapes or adhesive coatings.  
         [0010]     It should be noted that unit  10  could also be formed using only one liner. For example, unit  10  may include only liner  14  and optical films  16 . Folding liner  14  at folds  14   a  produces a Z-fold structure where both surfaces of liner  14  protect optical films  16 .  
         [0011]     As discussed above, current delivery formats for optical film strip  12  include winding strip  12  around a reel. Unit  10  provides several advantages over the reel format. Because strip  12  is not wound around a reel, there is no winding tension, which subsequently alleviates impressions that result from optical films layered adjacent to each other. Optical films  16  no longer curl when removed from strip  12 , because strip  12  is not wound. The overall volume of unit  10  is reduced by between about 20% and about 40% compared to the reel format. In addition, unit  10  is easily set up on a working table to remove liners  14  and  18  for assembly of optical film  16  into an optical display, and unit  10  is easy to package and transport.  
         [0012]      FIG. 2  is a representative embodiment of optical film strip  12 . Optical film strip  12  includes optical films  16  (shown in phantom), liner  18 , dot-line cuts  20  with cuts  20   a  and gaps  20   b , and pages  22 . Dot-line cuts  20  define pages  22  and define placement of folds  14   a  and  18   a , shown in  FIG. 1 , by scoring liners  14  and  18 . Dot-line cuts are only one example. Any of a number of types of scores, which are known in the art, besides dot-line cuts may also be used to define placement of folds.  
         [0013]     As shown, dot-line cuts  20  typically extend in parallel lines across most of the width of strip  12 . Tension may be placed on strip  12  while liners  14  and  18  are removed from optical films  16 . In order to prevent splitting along dot-line cuts  20  when tension is placed on strip  12 , dot-line cuts  20  end at least about 0.5 mm from the edges of liners  14  and  18 .  
         [0014]     Depending on the thickness of strip  12 , cuts  20   a  of dot-line cuts  20  vary in length between about 0.5 mm and 30 mm. Typically, the length of cuts  20   a  is between about 1.0 mm and about 2.0 mm. Generally, the length of cut  20   a  increases as the thickness of strip  12  increases. Gap  20   b , which is the spacing between each cut  20   a , has a length between about 0.5 mm and about 30 mm. Typically, gap  20   b  has a length of about 1.0 mm.  
         [0015]     Using two dot-line cuts  20  to define pages  22  usually allows pages  22  of strip  12  to lay flat when strip  12  is in a Z-fold structure. This is illustrated in  FIG. 1 . Depending on the thickness of strip  12 , more dot-line cuts  20  may be used to define pages  22 , however, one dot-line cut  20  may also be used if desired. Less typically, strip  12  can be folded into unit  10  without dot-line cuts  20 , but this would not be as efficient or accurate.  
         [0016]     Depending on the number of dot-line cuts  20  used between pages  22  and the thickness of strip  12 , each set of dot-line cuts  20  is spaced between about 0.1 mm and about 1.0 mm. Typically, spacing between dot-line cuts is greater than the thickness of strip  12 . In addition, each page  22  of strip  12  will generally be of equal size, although this is not required. The size of pages  22  will vary and depends upon the size of optical films  16  and the number of optical films  16  on each page  22 .  
         [0017]      FIG. 3  is a representative embodiment of a method of making optical film delivery unit  10 .  FIG. 3  includes strip  12  with liner  14 , optical films  16  and liner  18 ; dot-line cuts  20 ; blades  24  and collector  26 .  
         [0018]     To produce unit  10 , blades  24  cut through liners  14  and  18  to form dot-line cuts  20  at predetermined intervals along strip  12 . Strip  12  is then fed into collector  26  where it folds along dot-line cuts  20  to form a Z-fold structure. Unit  10  is subsequently packaged and shipped to a manufacturer for assembling optical films  16  into a display.  
         [0019]     Use of unit  10  instead of a reel does not require any special equipment or treatment by the manufacturer. Upon delivery to the manufacturer, strip  12  of unit  10  is fed into a dispenser to remove liner  14  and/or liner  18  from optical films  16 . Removal of liners  14  and  18  entails peeling back these layers from optical films  16  in opposing directions. The same equipment and process are used for the current reel format. Optical films  16  are then either manually or automatically placed into an optical display.  
         [0020]     Optical film delivery unit  10  provides several advantages over the current reel format for packaging and dispensing optical films. Unit  10  alleviates winding tension within strip  12  and impression and curl issues of optical films  16 . Unit  10  has a reduced volume compared to the reel format making it easy to package and transport.  
         [0021]     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.