| 摘要 |
PURPOSE:To make a frictional force of a sliding plane caused by a vertical drag small, and to facilitate a control by making the distribution of magnetic flux density of a permanent magnet nearly point symmetry. CONSTITUTION:When the plastic permanent magnet 14 is formed, gate positions G1 and G2 are provided in the position of point symmetry by the number of multiple of two. Thus, the increase and decrease of the magnetic flux density caused by the unevenness of the slope of magnetic powder which occurs in the gate position and a welding position at the time of forming can be reduced and an unbalanced magnetic attractive force (vertical drag) which occurs at the time of arranging the permanent magnet 14 in a yoke 6, can be made small, so that an objective lens driving device which is excellent in sliding characteristics, that means, the control of which is easy can be obtained.
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