| 摘要 |
PURPOSE:To obtain a magnetic circuit with high reliability by setting the inside peripheral diameter of a resin magnet having a high maximum energy product at the same level of the inside peripheral diameter of a top plate, and joining it with the inside peripheral diameter of a ring shaped ferrite magnet. CONSTITUTION:A top plate 1 and a ring shaped ferrite magnet 2 are stuck and constituted respectively in a state that they are fitted from an outside at a projecting part arranged at the center of a bottom plate 3, and whole of them are mounted at a frame 4 through the top plate 1. A resin magnet 5 is joined with the inside peripheral plane of the ring shaped ferrite magnet 2. The resin magnet 5 is obtained so that a samarium-cobalt system is kneaded in a resin, such as a nylon, a 'Jurakon(R),' a polycarbonate, etc., and a magnetic field is formed, and the energy product is 7-10MGOe. As a result, the inside peripheral diameter of the resin magnet 5 becomes almost equal with that of the top plate 1. In this way, a leakage flux 8 leaked from the inside peripheral side part of the top plate 1 to the projecting part side of the bottom plate 3 can be reduced.
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