| 摘要 |
PURPOSE:To obtain the compact magnetic circuit where sensitivity can be readily adjusted by combining cast magnets and magnets of high coercive force. CONSTITUTION:The cylindrical cast magnet 11 and the cylindrical magnet 13 of high coercive force, and likewise the magnets 12 and 14 are arranged in parallel with each other. The magnets 11 and 13 are held between one end of a core 15 and a magnetic path plate 16, and the magnets 12 and 14 are held between the other end of the core 15 and the magnetic path plate 16. A movable coil 22 which surrounds the core 15 generates a rotating torque in response to the given coil current. When the sensitivity is adjusted by applying the alternating magnetic field in the conventional method, the magnetic forces of the high coercive magnets 13 and 14 are not changed, but the magnetic force of the cast magnets 11 and 12 are reduced, the magnetic flux density of the magnetic circuit at a whole is changed, and the sensitivity can be adjusted. By this method, compact instruments whose fine adjustment is easy can be obtained. |
