| 摘要 |
PURPOSE:To prevent the transition into a demagnetized state due to the external force such as vibration, shocks, and the like, by limiting the rotating position energyzed by a permanent magnet, which puts the magnetizing surface of a magnetic- circuit block into an energyzed state, by the magnetic torque toward a stopper. CONSTITUTION:The permanent magnet holding device 30 is constituted by a pair of magnetic members 32, the magnetic circuit block 36 comprising a nonmagnetic plate 34 which is arranged in said magnetic members 32 and incorporated as one body, and a permanent magnet 38. A through hole 50 is formed to a bore 40 having a circular cross section in the magnetic member 32, so that the stopper 52 can be inserted into said through hole 50. The tip of said stopper 52 is extruded into the bore 40 so as to contact with one side of an extruded portion 46. The tip of the stopper 52 stops the clockwise rotation of the magnet 38 in the block 36. When an operating knob 48, which rotates the magnet 38, is operated in the counterclockwise direction, the side of the extruded portion 46 is contacted with the tip of the stopper 52, the rotation of the magnet 38 larger than the specified angle is stopped, and the transition into the demagnetized state by the external force can be prevented. |
