| 摘要 |
Solenoid apparatus. First and second electrical windings are supplied current and the current flow through each of the windings induces respective magnetic fields the strengths of which are functions of the average current flow therethrough and the magnetic fields combine to produce a net magnetic field. An armature is movable in either of two directions between a first position and a second position through a predetermined number of discrete intermediate positions. The armature is biased toward one of the intermediate positions constituting a reference position and the position of the armature at any one time is determined by the strength of the net magnetic field and a biasing force on the armature. A current source supplies current to the windings and the current source is controllable to vary the average current flow in each winding to produce movement of the armature from one position to another. The average current flow in each winding is variable between a minimum and a maximum value in steps and the predetermined number of intermediate positions to which the armature is movable corresponds to the number of these steps.
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