Rotation mechanism

Abstract

A rotation mechanism includes a shaft portion, a bearing portion, a protruding portion, and a stopper. The bearing portion configured to rotate with respect to a predetermined axis as a center of rotation and configured to slide relative to an outer periphery of the shaft portion. The protruding portion protrudes from the shaft portion. The stopper is integrally formed the bearing portion. The stopper faces the protruding portion. A length of the protruding portion in a direction in which the protruding portion protrudes is larger than a distance from the center of rotation to a sliding portion where the bearing portion slides relative to the outer periphery of the shaft portion.

What is claimed is: 
     
         1 . A rotation mechanism comprising:
 a shaft portion;   a bearing portion configured to rotate with respect to a predetermined axis as a center of rotation;   a first protruding portion protruding from the shaft portion;   a plurality of second protruding portions protruding from the bearing portion to the shaft portion and configured to slide relative to an outer periphery of the shaft portion; and   a stopper integrally formed with the bearing portion, the stopper facing the first protruding portion.   
     
     
         2 . The rotation mechanism according to  claim 1 , wherein the plurality of second protruding portions includes three second protruding portions. 
     
     
         3 . The rotation mechanism according to  claim 2 , wherein
 the three second protruding portions are in contact with the shaft portion at first point, second point and third point, respectively and   the center of rotation exists inside a triangle formed from the first point, the second point and the third point.   
     
     
         4 . The rotation mechanism according to  claim 3 , wherein two second protruding portions among the three second protruding portions are arranged in the vicinity of an opening of the bearing portion. 
     
     
         5 . The rotation mechanism according to  claim 4 , wherein a length of the first protruding portion in a direction in which the first protruding portion protrudes is larger than a distance from the center of rotation to a sliding portion where each of the plurality of second protruding portions slides relative to the outer periphery of the shaft portion. 
     
     
         6 . The rotation mechanism according to  claim 1 , wherein the plurality of second protruding portions includes two second protruding portions. 
     
     
         7 . The rotation mechanism according to  claim 6 , wherein the two second protruding portions are arranged in the vicinity of an opening of the bearing portion. 
     
     
         8 . The rotation mechanism according to  claim 7 , wherein a length of the first protruding portion in a direction in which the first protruding portion protrudes is larger than a distance from the center of rotation to a sliding portion where each of the plurality of second protruding portions slides relative to the outer periphery of the shaft portion. 
     
     
         9 . A rotation mechanism comprising:
 a shaft portion;   a bearing portion configured to rotate with respect to a predetermined axis as a center of rotation;   a first protruding portion protruding from the shaft portion;   a plurality of second protruding portions protruding from the shaft portion to the bearing portion and configured to slide relative to an inner surface of the bearing portion; and   a stopper integrally formed with the bearing portion, the stopper facing the first protruding portion.   
     
     
         10 . The rotation mechanism according to  claim 9 , wherein the plurality of second protruding portions includes three second protruding portions. 
     
     
         11 . The rotation mechanism according to  claim 10 , wherein
 the bearing portion includes a first area, a second area and a third area,   the first area, the second area and the third area is configured to slide with the three second protruding portions, respectively, and   a distance between the center of rotation and the inner surface of the bearing portion in the first area, a distance between the center of rotation and the inner surface of the bearing portion in the second area, and a distance between the center of rotation and the inner surface of the bearing portion in the third area are different.   
     
     
         12 . The rotation mechanism according to  claim 11 , wherein the three second protruding portions have different heights, respectively. 
     
     
         13 . The rotation mechanism according to  claim 9 , wherein the plurality of second protruding portions includes two second protruding portions. 
     
     
         14 . The rotation mechanism according to  claim 9 , wherein a length of the first protruding portion from the center of rotation is shorter than a length of at least one of the plurality of second protruding portion from the center of rotation. 
     
     
         15 . A rotation mechanism comprising:
 a shaft portion;   a bearing portion configured to rotate with respect to a predetermined axis as a center of rotation and configured to slide relative to an outer periphery of the shaft portion;   a first protruding portion protruding from the shaft portion; and   a stopper integrally formed with the bearing portion, the stopper facing the first protruding portion,   wherein an edge of the stopper has a forked shape having two sub-edges protruding to the first protruding portion.   
     
     
         16 . The rotation mechanism according to  claim 15 , wherein
 a surface of the first protruding portion has a convex curved shape,   the edge of the stopper has a concave curved shape between the two sub-edges of the forked shape, and   a radius of curvature of the convex curved shape is larger than a radius of curvature of the concave curved shape.