Method and apparatus for guiding a moving tape

Abstract

Method and apparatus for guiding a moving tape having a tape edge parallel to a direction of motion of the tape wherein the tape is received tangentially on a curved surface having an edge. Force applied to the tape is increased as the tape drifts farther away from a nominal position so as to move the tape away from the edge of the surface. Lateral motion of the tape is dampened by breaking up an air-cushion between the tape and the curved surface.

1 . A method of guiding a moving tape having a tape edge parallel to a direction of motion of the tape, said method comprising: 
 receiving the tape tangentially on a curved surface having an edge;    applying a force to the tape to move the tape edge away from the edge and towards a nominal position, wherein the force applied increases as the tape drifts farther away from the nominal position; and    dampening lateral motion of the tape by breaking up an air-cushion between the tape and the curved surface.    
   
   
       2 . The method of  claim 1  wherein applying a force to the tape comprises: 
 applying a force that increases approximately linearly with a distance of the tape from the nominal position.    
   
   
       3 . The method of  claim 1  wherein applying a force to the tape comprises: 
 applying a force that increases approximately as a square root of a difference between a square of the nominal distance of the tape edge from the edge of the curved surface and a square of a distance of the tape edge from the edge of the curved surface.    
   
   
       4 . The method of  claim 1  wherein breaking up an air-cushion comprises: 
 directing air away from the curved surface at a plurality of locations.    
   
   
       5 . The method of  claim 4  wherein the plurality of locations is selected from the group consisting of two, three, four, and five.  
   
   
       6 . A tape guide capable of guiding a moving tape having a tape edge parallel to a direction of motion of the tape, said tape guide comprising: 
 means for receiving the tape on a surface having an edge; and    means for applying a force to the tape edge to counter drift as the tape drifts from a nominal position, wherein the force applied increases as the tape drifts farther away from its nominal position.    
   
   
       7 . The tape guide of  claim 6  wherein the force applying means comprises: 
 a curved transition between the edge and the surface.    
   
   
       8 . The tape guide of  claim 6  wherein the force applying means comprises: 
 a curved surface with a uniform radius of curvature.    
   
   
       9 . A tape guide roller comprising: 
 hub having a curved surface;    range restrictors capable of restricting a position of a tape edge on the curved surface of the hub;    dampeners capable of dampening lateral motion of the tape on the curved surface of the hub; and    friction enhancers capable of enhancing friction between the tape and the curved surface of the hub.    
   
   
       10 . The tape guide roller of  claim 9  wherein the range restrictors comprise: 
 first flange extending out from a first end of the hub; and    second flange extending out from a second end of the hub.    
   
   
       11 . The tape guide roller of  claim 10  wherein the dampeners comprise: 
 corners defining an intersection of the curved surface of the hub and the first flange, and an intersection of the curved surface of the hub and the second flange, each corner configured to apply progressively more force to an edge of the tape as the edge of the tape moves through the corner toward a flange.    
   
   
       12 . The tape guide roller of  claim 11  wherein each corner comprises a curve.  
   
   
       13 . The tape guide roller of  claim 12  wherein the curve is circular.  
   
   
       14 . The tape guide roller of  claim 13  wherein the circular curve has a radius substantially in a range of 0.03 mm to 0.5 mm.  
   
   
       15 . The tape guide roller of  claim 11  wherein each corner comprises a chamfer.  
   
   
       16 . The tape guide roller of  claim 9  wherein the friction enhancers comprise a plurality of grooves disposed in the curved surface of the hub.  
   
   
       17 . The tape guide roller of  claim 16  wherein the grooves are V-shaped having a width substantially in the range of 0.2 mm to 0.6 mm and a depth substantially in the range of 0.1 mm to 0.3 mm.  
   
   
       18 . The tape guide roller of  claim 16  wherein the number of grooves is selected from the group consisting of two, three, four, and five.