Patent ID: 7781924

Claim:
A motor comprising: a cylindrical magnet that is circumferentially multipolar-magnetized, said magnet having inner and outer peripheral surfaces; a rotor made of a soft magnetic material and fixed to the inner peripheral surface of said magnet, said rotor including a rotary shaft; a first stator having first and second outer magnetic pole portions disposed at respective positions which are phase-shifted from each other by a predetermined angle with respect to a rotation center of said magnet, said first and second outer magnetic pole portions being opposed to the outer peripheral surface of said magnet with a predetermined gap therebetween; a second stator having third and fourth outer magnetic pole portions disposed at positions circumferentially close to said first and second outer magnetic pole portions, respectively, said third and fourth outer magnetic pole portions being opposed to the outer peripheral surface of said magnet with a predetermined gap therebetween; a first bearing that bears one end of the rotary shaft of said rotor and made of soft magnetic material; a second bearing that bears the other end of the rotary shaft of said rotor and made of soft magnetic material; a first annular coil that excites said first and third outer magnetic pole portions; and a second annular coil that excites said second and fourth outer magnetic pole portions, wherein said first and second stators comprise first and second flat plate portions, respectively, extending orthogonally to said rotary shaft of said rotor, wherein said first and second outer magnetic pole portions extend from said first flat plate portion opposing said third and fourth outer magnetic pole portions, respectively, and said third and fourth outer magnetic pole portions extend from said second flat plate portion opposing said first and second outer magnetic pole portions, respectively, wherein said first stator holds said first bearing, and said second stator holds said second bearing, with said second flat plate portion of said second stator extending over said rotor and supporting the rotary shaft of the rotor via the second bearing, and wherein said first and second stators are magnetically coupled to each other via said second bearing, the rotary shaft of said rotor, said core, and said first bearing.