| 摘要 |
PROBLEM TO BE SOLVED: To provide an actuator the linearity of which is improved. SOLUTION: A needle 26 is arranged in a yoke 1 on which coils 22 and 24 are mounted. The needle 26 includes a permanent magnet 28, magnetic pole pieces 30 and 32 fixed to the both main faces of the permanent magnet 28, and supporting shaft 34 penetrating the permanent magnet 28 and the magnetic pole pieces 30 and 32. The yoke 12 is provided with an extended part 60 formed, so as to extend to a region interposed by the coil 22 and the magnetic pole piece 30, and an extended part 60 formed so as to extend to a region interposed by the coil 24 and the magnetic pole piece 32. Thus, the existence of the extended part 60 is realized so that a magnetic force can act on the needle 26, even if the needle 26 is displaced in a relatively wide range, and the fluctuations of magnetic flux density in the magnetic circuit can be suppressed.
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