| 摘要 |
PURPOSE:To perform an efficient magnetic circuit without decreasing a magnetic efficiency by first providing a yoke of the shape similar to the coil shape without using a magnet at the outside of the coil. CONSTITUTION:A guide rail 4 is used also as a center yoke to be used also as a guide rail of a guide roller 3. Since a section of a coil 5 is of a circular shape, a center yoke is formed in a circular sectional shape. An intermediate yoke 6 of the circular shape concentric with the coil 5 is disposed, and a magnet 7 is provided at the outside. An outer yoke 8 is disposed at the outside to form a magnetic circuit with an inner yoke 4. With this construction, since a yoke of an arbitrary section can be accurately formed and the same shape as the coil, an air gap can be accurately decided, and the magnetic circuit can be stably formed. |
