Noncontact web transporting apparatus

Abstract

A curved area is a jet surface for jetting the air from air jet openings formed in a zigzag state. Two rollers are disposed in parallel with a turn bar so as to be adjacent to both ends of the jet surface in a transporting direction of a web. The roller rotates, contacting with a surface opposite to a levitation surface of the web, when the web is transported. Oscillation of the web is prevented and the web is prevented from coming into contact with the turn bar. Further, the air jetted from the jet surface is prevented from leaking in the transporting direction. The air leaks in a width direction of the web. An air pressure is prevented from lowering at both ends of the jet surface so that a levitation amount of the web becomes uniform.

1 . A noncontact web transporting apparatus for transporting a web in a noncontact manner, said noncontact web transporting apparatus comprising: 
 a turn bar for levitating said web and altering a transport direction thereof, said turn bar having a jet surface formed with a plurality of jet openings from which gaseous matter is jetted, and the gaseous matter jetted from said jet openings being sprayed to a first surface of said web; and    a pair of first rollers disposed so as to be parallel with said turn bar, said first rollers being adjacent to both ends of said jet surface relative to the transport direction of said web to rotate, coming into contact with a second surface of said web opposite to said first surface.    
     
     
         2 . A noncontact web transporting apparatus according to  claim 1 , further comprising: 
 a winding-angle changing mechanism for changing a winding angle of said web of which said second surface is wound on said roller, said winding-angle changing mechanism decreasing said winding angle when said web has high rigidity.    
     
     
         3 . A noncontact web transporting apparatus according to  claim 2 , wherein said winding-angle changing mechanism comprising: 
 a pair of second rollers disposed at a passage of said web located below said turn bar, said second rollers being also disposed so as to be parallel with said turn bar to rotate, coming into contact with said second surface of said web; and    a shifting mechanism for horizontally moving said second roller.    
     
     
         4 . A noncontact web transporting apparatus according to  claim 3 , wherein the pair of said second rollers are disposed at symmetrical positions about said turn bar.  
     
     
         5 . A noncontact web transporting apparatus according to  claim 4 , wherein an interval of said second rollers is longer that an interval of said first rollers.  
     
     
         6 . A noncontact web transporting apparatus according to  claim 5 , wherein said jet openings formed in the jet surface of said turn bar are arranged in a zigzag state.  
     
     
         7 . A noncontact web transporting apparatus according to  claim 6 , wherein said jet surface has a U-shaped cross section in the transport direction of said web.  
     
     
         8 . A noncontact web transporting apparatus according to  claim 7 , wherein said turn bar is provided with a duct for supplying said gaseous matter to the inside thereof.  
     
     
         9 . A noncontact web transporting apparatus according to  claim 7 , wherein said gaseous matter is the air.  
     
     
         10 . A noncontact web transporting apparatus according to  claim 9 , wherein said web is a photosensitive printing plate.