Ex parte MIYAZAWA et al. - Page 3

          Appeal No. 1997-3279                                       Page 3           
          Application No. 08/240,702                                                  

          motor's efficiency.  The disposition of the stator's magnetic               
          poles simplifies assembly.                                                  

               Claim 21, which is representative for our purposes,                    
                    21. A brushless DC motor comprising:                              
                    a rotor having a rotor yoke and a rotor magnet                    
               forming a plurality of magnetic poles in a                             
               circumferential direction disposed on the rotor                        
                    a stator having a stator yoke with a plurality                    
               of magnetic poles alternately disposed at regular                      
               intervals in the circumferential direction on the                      
               stator yoke having a constant air gap next to the                      
               rotor magnet,                                                          
                    a coil unit disposed on the stator yoke and                       
               having a magnetic field coil for exciting the                          
               magnetic poles of the stator,                                          
                    a magnetic pole sensing element set at a                          
               position shifted in the circumferential direction                      
               from an intermediate position of one magnetic pole                     
               of the rotor magnet for detecting a pole of the                        
               rotor magnet,                                                          
                    wherein an open angle of the magnetic poles of                    
               the stator is set at no less than 75% but less than                    
               100% of an open angle per magnetic pole of the rotor                   
               so that a static stable point position where the                       
               rotor stops by a cogging torque in a magnetic                          
               circuit consisting of the rotor and stator is in                       
               vicinity of a maximum point of torque generated by                     

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Last modified: November 3, 2007