Reel

Abstract

A reel in which the planarity of a reel plate after insert molding may be ensured. The reel plate is formed into a concave shape, and by insert molding, the reel plate is made substantially flat. When a reel plate is insert molded, the reel plate is deformed in the direction to protrude in the direction to the outside of the reel by shrinkage stress of resin after molding. Therefore, by concaving the reel plate in advance into a concave shape, even if the reel plate is protruded by the shrinkage stress of the resin after insert molding, the amount of protruding may be absorbed by the amount of concaving, and the shape of the reel plate may be made substantially flat. That is to say, the planarity of the reel plate may be obtained. By doing so, the meshing of the reel gear that surrounds the reel plate with the drive gear on the rotation shaft side of the drive device may be improved.

1 . A reel comprising:
 a hub, for winding recording tape thereon, the hub being substantially a bottomed cylindrical shape;   a reel plate, being magnetically attachable to a rotation shaft on a drive device side, being formed into a concave shape, and being insert molded to the bottom surface of the hub and;   the reel plate surface being substantially flat after being insert molded.   
   
   
       2 . The reel according to  claim 1 , wherein an amount of concavity of the reel plate is such that the reel plate is configured to be flattened within the range of elastic deformation of the reel plate. 
   
   
       3 . The reel according to  claim 1 , wherein an amount of concavity of the reel plate is determined according to the material, thickness and/or outline shape of the reel plate. 
   
   
       4 . A reel comprising:
 a hub, for winding recording tape thereon, the hub being substantially a bottomed cylindrical shape;   a reel plate;   a flange, wherein   the reel plate is initially formed into a concave shape when viewed in cross-section, and after the reel is molded the reel plate is substantially flat in cross-section.   
   
   
       5 . A recording tape cartridge comprising a reel according to  claim 1  or  claim 4 . 
   
   
       6 . A reel manufacturing method for a reel comprising a bottomed cylindrical hub, a reel plate, and a flange, the method comprising:
 forming the reel plate into a concave shape;   inserting the reel plate into a mold; and   integrally forming the reel plate with the hub and the flange.