| 摘要 |
<p>The invention intends to provide an electromagnetic transducer which can improve conversion efficiency by reducing the weight of a rotor and thinning a rotor shaft, and which has succeeded in reduction of both size and weight. An electromagnetic transducer includes a rotor comprising a plurality of magnets with N and S poles arrayed alternately in the direction of rotation of the rotor, and a back yoke for supporting the plurality of magnets. The back yoke is formed such that an area of a section area of the back yoke sectioned by a plane passing the center of each magnet as viewed in plan and the rotor shaft is smaller than a sectional area of another portion of the back yoke depending on distribution of magnetic force lines generated inside the back yoke between the N and S poles of the adjacent magnets. With such a reduction of the sectional area of the back yoke, the weight of the back yoke and hence the overall weight of the rotor can be reduced while the magnetic force lines flowing into the magnet are prevented from being saturated. <IMAGE></p> |
