| 摘要 |
PROBLEM TO BE SOLVED: To enable improvement of propelling efficiency per unit volume by forming each part to allow formation of the square external shape of a cylindrical moving coil arranged within the cylindrical gap between an external yoke and an internal yoke. SOLUTION: An internal yoke 1 is fixed to a yoke holder 10 via a fitting screw 11, a square pole is formed by forming a square external shape of an internal yoke 1 and the first and second permanent magnetic groups 20, 21 consisting of the plate type permanent magnet pieces 3a, 3b are formed at the external circumference of the internal yoke 1. A cylindrical moving coil 5 provided in a cup type coil holder 6 is arranged within the cylindrical gap 4 formed between the internal yoke 1 and external yoke 30. This cylindrical moving coil 5 is formed of a first and a second cylindrical moving coil pieces 5a, 5b corresponding to the first and second permanent magnet groups 20, 21 via the gap 50. Here, when an energizing signal is fed to the cylindrical moving coil pieces 5a, 5b, a coil holder 6 and an output shaft 36 are moved linearly.
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