Structure of roters in stepping motors

Abstract

The objects of the present invention is to provide a stepping motors capable of rotating with not only high speed but also less undesired vibration and noises, and moreover enabling a simpler, smaller manufacturing equipment thereof to be constructed. A magnetic component 5 of the present invention comprises a magnetic component potions 6 and 7 , of which circumferential surface portions each are magnetized in multipole along their circumferential surfaces or magnetized radially in the radial direction, and the magnetic component portions are set up together in the axial direction. As the magnetic component portions 6 and 7 of the magnetic component 5 in the rotor 2 are formed ring-like, the distribution curve of the magnetic flux in the magnetic field is a sine wave, thus this type of stepping motor is capable of reducing undesired vibration and noises as compared with others that have a rotor with teeth on its circumferential surface. In addition, it has less inertia so that it has a high quality capable of responding faster. The magnetic component 5 comprises a first and second magnetic component portions 6 and 7 that are to be combined together, thus they are capable of receiving magnetic force independently, proving themselves to be more controllable with two-phase type. And also it is possible to construct a smaller manufacturing equipment, because the physical size of the magnetizing apparatus for the magnetic components can be determined on the basis of the size of the first and second magnetic component portions 6 and 7.

What is claimed is:  
     
         1 . A structure of a rotor in a stepping motor having a rotor comprising magnetic component whose circumferential part is magnetized in multipole along the circumferential surface thereof, said stepping motor being capable of forcing said rotor to rotate by magnetic force provided between magnetic poles of said rotor and excited salient poles of a stator, characterized in that said magnetic component comprises two magnetic component portions each shaped as an approximate ring, and said two magnetic component portions are either combined with each other or set up separately at an appropriate spacing between them.  
     
     
         2 . A structure of a rotor in a stepping motor according to  claim 1  wherein said two magnetic component portions have a plurality of N-poles and S-poles arranged alternately at appropriate spacing inbetween, said magnetic components are arranged so that contrary poles face each other.  
     
     
         3 . A structure of a rotor in a stepping motor having a rotor comprising magnetic component magnetized in its radial direction, said stepping motor being capable of forcing said rotor to rotate by magnetic force provided between magnetic poles of said rotor and excited salient poles of a stator, characterized in that said magnetic component comprises two magnetic component portions each shaped as an approximate gear, and said two magnetic component portions have, on their circumferential surface, convex portions that extend in the axial direction and are disposed at appropriate spacing, and said two magnetic component portions are either combined with each other or set up separately at appropriate spacing between them.  
     
     
         4 . A structure of a rotor in a stepping motor according to  claim 3 , wherein said convex portions are radially magnetized so that said convex portions on one magnetic component portion have the opposite pole to said convex portions on the other magnetic component portion, and said convex portions are so arranged that they are in aligned arrangement, when viewed in the axial direction.  
     
     
         5 . A structure of a rotor in a stepping motor according to  claim 3  wherein said two magnetic component portions are magnetized with poles contrary to each other and, 
 wherein said two magnetic component portions have convex portions opposing to concave portions when viewed in the axial direction.