Drive unit

Abstract

In order to reduce load supported by a support mechanism for supporting a movable part so as to prevent the movable part from moving in a horizontal direction when stress is generated thereon in the horizontal direction, there is provided a drive unit including a primary side having a magnetic body around which a coil is wound, and a secondary side having a plurality of permanent magnets, the primary side including magnetic poles and step portions provided on the magnetic poles. The width of each step portion is smaller than the width of each permanent magnet.

What is claimed is:  
     
         1 . A drive unit comprising: 
 a primary side comprising a magnetic body around which a coil is wound; and    a secondary side comprising a plurality of permanent magnets, an irregular magnetic plate, or a conductor plate; wherein 
 the primary side includes a magnetic pole in which a step portion is provided.  
   
     
     
         2 . A drive unit comprising: 
 a first core having first opposed portions;    a second core having second opposed portions;    a primary side including the first core and the second core, around which primary side a coil is wound; and    a secondary side disposed between the first opposed portions and between the second opposed portions; wherein 
 the primary side is provided with a step portion.  
   
     
     
         3 . A drive unit comprising: 
 a first core having first opposed portions;    a second core having second opposed portions;    a primary side including the first core and the second core, around which primary side a coil is wound; and    a secondary side disposed between the first opposed portions and between the second opposed portions; wherein 
 at least one of the first opposed portions and the second opposed portions is provided with a step portion.  
   
     
     
         4 . The drive unit according to  claim 1 , wherein 
 the height of the step portion is larger than the distance of an air gap between the primary side and the secondary side.    
     
     
         5 . The drive unit according to  claim 2 , wherein 
 the height of the step portion is larger than the distance of an air gap between the primary side and the secondary side.    
     
     
         6 . The drive unit according to  claim 3 , wherein 
 the height of the step portion is larger than the distance of an air gap between the primary side and the secondary side.    
     
     
         7 . The drive unit according to  claim 2 , wherein 
 each of the first core and the second core comprises an upper magnetic pole tooth and a lower magnetic pole tooth, the height of the step portion being smaller than the width of the upper magnetic pole tooth or the lower magnetic pole tooth.    
     
     
         8 . The drive unit according to  claim 3 , wherein 
 each of the first core and the second core comprises an upper magnetic pole tooth and a lower magnetic pole tooth, the height of the step portion being smaller than the width of the upper magnetic pole tooth or the lower magnetic pole tooth.    
     
     
         9 . The drive unit according to  claim 1 , wherein 
 the secondary side comprises a permanent magnet, the width of the step portion being smaller than the width of the permanent magnet.    
     
     
         10 . The drive unit according to  claim 2 , wherein 
 the secondary side comprises a permanent magnet, the width of the step portion being smaller than the width of the permanent magnet.    
     
     
         11 . The drive unit according to  claim 3 , wherein 
 the secondary side comprises a permanent magnet, the width of the step portion being smaller than the width of the permanent magnet.    
     
     
         12 . The drive unit according to  claim 3 , wherein 
 each of the first core and the second core comprises an upper magnetic pole tooth and a lower magnetic pole tooth,    the secondary side comprises a permanent magnet,    the step portion comprises a protrusion provided on the upper magnetic pole tooth or and a lower magnetic pole tooth so as to protrude therefrom toward the secondary side, the height of the protrusion being smaller than the widths of the upper magnetic pole tooth and the lower magnetic pole tooth, the width of the protrusion being smaller than the width of the permanent magnet.