Device for winding and/or unwinding a film at a constant speed

Abstract

A device for winding and/or unwinding a film at a constant speed includes a reel comprising two coaxial annular support areas, having the same diameter, which are separated by a concavity and which are spaced out from one another by a distance that is slightly smaller than the width of the film. The two support areas pivot freely. Guide means guide the film laterally in order to wind the film on the reel such that the lateral edges thereof rest on the two support areas of the reel respectively. Two parallel drive belts are supported respectively on said edges, along the length of an arc of circle with a predetermined angle at the center. The invention applied to a film in an optoelectronic apparatus, such as a scanning and analysis device.

1 . A device for winding and/or unwinding a film at a constant speed, including: 
 a reel comprising two coaxial annular support areas, of equal diameter, which are separated from each other by a concavity and which are spaced out from one another by a distance that is slightly smaller than a width of the film, the two support areas pivoting freely,    guide means which guide the film laterally in order to wind it onto the reel such that lateral edges of the film bear on the two respective support areas of the reel, and    two parallel drive belts supported on said respective edges along a length of an arc of a circle subtending a predetermined angle at a center.    
     
     
         2 . The device as claimed in  claim 1 , wherein said support areas are connected to each other.  
     
     
         3 . The device as claimed in  claim 1 , wherein said support areas are independent of each other in rotation.  
     
     
         4 . The device as claimed in  claim 1 , wherein said belts are driven by a motor.  
     
     
         5 . The device as claimed in  claim 1 , wherein the reel is a necked reel comprising two circular lateral ends on which the lateral edges of the film rest.  
     
     
         6 . The device as claimed in  claim 5 , wherein said necked reel comprises an axisymetric concave form situated between two ends.  
     
     
         7 . The device as claimed in  claim 1 , wherein said reel comprises a spindle on which it rotates.  
     
     
         8 . The device as claimed in  claim 7 , wherein said spindle is able to move translationally and is guided along an oblong drilling.  
     
     
         9 . The device as claimed in  claim 8 , wherein a main spindle of said drilling is oriented perpendicular to a tangential plane of application of the belts to the edges of the film.  
     
     
         10 . The device as claimed in  claim 1 , wherein said guide means comprise guide arms mounted around the reel.  
     
     
         11 . The device as claimed in  claim 10 , wherein at least one of said guide arms pivots about an axis.