Bobbin and sewing machine

Abstract

A bobbin detachably installed into an inner hook of a sewing machine is disclosed. The bobbin includes a bobbin shaft; and a pair of flanges that are provided at both axial ends of the bobbin shaft. The bobbin shaft is cylindrical and includes a first opening and a second opening defined on axial ends thereof, the bobbin shaft being provided with a restriction member in a proximity of either of the first and the second opening to allow attachment of the bobbin to the inner hook through the first opening.

1 . A bobbin detachably installed into an inner hook of a sewing machine comprising:
 a bobbin shaft;   a pair of flanges that are provided at both axial ends of the bobbin shaft;   wherein the bobbin shaft is cylindrical and includes a first opening and a second opening defined on the axial ends thereof, the bobbin shaft being provided with a restriction member in a proximity of either of the first and the second opening to allow attachment of the bobbin to the inner hook through the first opening.   
     
     
         2 . The bobbin according to  claim 1 , wherein the restriction member is provided in the proximity of the second opening such that the second opening is narrowed to inhibit attachment of the bobbin. 
     
     
         3 . The bobbin according to  claim 2 , wherein the restriction member is provided on an inner surface of the second opening and comprises one or more protrusions protruding so as to narrow the second opening. 
     
     
         4 . The bobbin according to  claim 1 , wherein the restriction member is provided on an inner surface of the first opening and comprises a spreading section that widens the first opening relative to the second opening to allow attachment of the bobbin to the inner hook. 
     
     
         5 . The bobbin according to  claim 4 , wherein the spreading section comprises a taper that is inclined to spread out toward an opening end thereof. 
     
     
         6 . A sewing machine comprising:
 an inner hook that detachably installs a bobbin provided with a bobbin shaft and a pair of flanges at both axial ends of the bobbin shaft;   wherein the bobbin shaft is cylindrical and includes a first opening and a second opening defined on axial ends thereof, the bobbin shaft being provided with a restriction member in a proximity of either of the first and the second opening to allow attachment of the bobbin to the inner hook through the first opening, and   wherein the inner hook is provided with a first fitting section that fits with the first opening and not with the second opening, the bobbin being attached to the inner hook only through the first opening by the fitting of the first fitting section and the first opening.   
     
     
         7 . The sewing machine according to  claim 6 , further comprising a thread winder that is provided with a thread winding shaft to which the bobbin is detachably attached and that winds the bobbin with a thread supplied from a thread spool by rotating the thread winding shaft, the thread winding shaft being provided with a second fitting section that fits with the first opening and not with the second opening, and the bobbin being attached to the thread winding shaft only through the first opening by the fitting of the second fitting section and the first opening.