| 摘要 |
PROBLEM TO BE SOLVED: To assure a sufficiently large adsorbing force and a repulsion force of a rubber sheet generated by an externally applied magnetic force, and also to prevent generation of a damage such as crack or the like for a longer period even if a bending stress is applied continuously. SOLUTION: A second diaphragm 98 is constituted with a double-color molded rubber sheet using a base sheet 114 and a magnetic sheet 116 as the raw materials. The double-color molded rubber sheet is formed by bonding the base sheet 114 and the magnetic sheet 116 through the heating and pressurizing processes under the laminated condition, and by vulcanizing the bonded base sheet 114 and magnetic sheet 116. Accordingly, the center side along the surface direction of the second diaphragm 98 where the base sheet 114 and the magnetic sheet 116 are laminated can be formed as a magnetic region M, and the external circumferential side formed only of the base sheet 114 can be formed as a non-magnetic and highly elastic region E having higher durability. COPYRIGHT: (C)2008,JPO&INPIT
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