| 摘要 |
PURPOSE:To obtain a low cost holding magnet which has the stable minimum attracting and holding voltage characteristic of a movable iron core by covering either a fixed iron core or the movable iron core with a non-magnetic material film. CONSTITUTION:A fixed iron core 1 made of a soft magnetic material, a movable iron core 2 which is made of the soft magnetic material and can move freely to approach to or separate from the fixed core 1, an electric winding wound around the magnetic path made of the fixed core 1 and the movable core 2 and a spring which works as mechanical drag force to separate the pole face 2a of the movable core 2 from the pole face 1a of the fixed core 1 when the current in the winding is less than a definite value are provided. Here, either the fixed core 1 or the movable core 2 is covered with a non-magnetic material film (copper plating) 5. This enables low cost mass production, the little dispersion of film thickness, the improvement of the precision of the dimension of the gap of the non-magnetic material between the pole faces when the pole face 1a of the fixed core 1 and the pole face 2a of the movable core 2 are attracted and stabilizing the minimum attracting and holding voltage of the movable core.
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