| 摘要 |
The invention relates to a limited rotation galvanometer having a shaft adapted to be deflected in accordance with an electrical drive signal applied to the galvanometer, the galvanometer comprising a stator assembly formed of at least one stationary permanent magnet and at least one pole piece cooperatively arranged about a hollow bore, a rotor associated with the shaft and mounted to turn in the hollow bore, and an electrical winding wound about the pole piece and adapted to receive the drive signal, this stator assembly and rotor defining magnetic circuitry for operation of the galvanometer, the deflection of the rotor being dependent upon the rigidity of the stator assembly and the value of the torque applied between the stator assembly the rotor by the application of the drive signal to the winding. According to the invention the galvanometer includes a molded, hoop-like outermost layer of rigid, reinforced stress-resistant synthetic resin material extending continuously around the exterior of the galvanometer, the synthetic resin material having the property of shrinking at least 1% during solidification, or preferably, the synthetic resin material being nylon, the layer engaging the outer surfaces of the winding, the magnet, and the pole piece, the molded hoop-like layer residing under substantial pre-stress hoop tension as the result of shrinkage during solidification of the synthetic resin material during molding, the molded hoop-like external layer applying stress to the stator assembly, thereby to force the magnet and the pole piece against one another, thereby imparting rigidity to the stator assembly and contributing to the accuracy of the deflection of the galvanometer.
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