A micro motor for a timepiece comprises a curved magnetic core, a coil winding wound on the magnetic core, a stator connected to the magnetic core to define therewith a closed magnetic flux path and having an opening therein in which a rotor is rotatably disposed. The stator comprises a pair of stator pieces each connected at one end to a respective end portion of the curved magnetic core and the stator pieces have curved portions extending at least partly along the curvature of said curved magnetic core to thereby form a compact overall assembly.
A bipolar stepping motor includes, a single stator sheet, an air gap between the ends of the stator sheet, a rotor between the ends of the stator sheet, and a coil which encompasses a portion of the stator sheet. The stator sheet is of essentially annular configuration and is surrounded over a substantial portion of its periphery by a coil carrier. The coil is applied on the carrier in the form of a ring core winding. A carrier plate is attached to the stator sheet in the vicinity of the air gap. This plate carries a shaft of the rotor and serves as means for attaching the motor to another structure.
A stator for a stepping motor comprises a cylindrical coil of compact size formed by winding wire directly on the center portion of a core. This center portion is coated with a film formed of a hard, compact insulating material adhering strongly to the core. An electrophoresis operation is used to obtain a film of minimum thickness in an efficient manner. The core includes end lugs which are bare on one face so that metallic contact can be established with the pole pieces of the stator. Prior to electrophoresis, the faces of the lugs intended to be bare are covered with a mask of synthetic material, preferably deposited while dissolved in a suitable solvent.
A small synchronous motor is provided with a stator winding wound around a stator core. Conversion efficiency is improved by setting the ratio of the coil length (L) to the thickness between the center of the core and the outer most periphery of the coil (R) to be L/R to 40.
A reversible two-phase electromechanical transducer comprises a stator (2) extending primarily over three levels and a rotor (38) including a multipolar permanent magnet (48) located between first and second principal stator parts (4, 8). The first stator part defines a stator hole and first and second principal magnetic poles (80, 82) magnetically coupled to secondary magnetic poles formed by the castellations (70) of a circular gapped crown located on the edge of the stator hole. The second principal stator portion defines at least one third principal magnetic pole (90), such second principal stator portion being magnetically coupled to each of the first and second principal magnetic poles by means of respective first and second magnetic flux guidance legs (12, 13), each bearing an energization winding (28, 29).
Motor-driven movement for timepieces wherein stator block core is formed in ring-shape with a magnetic material of a rounded bar, magnetic poles formed at both core ends are disposed as directed radially inward of the core and rotary shaft of minute hand wheel of output gear train meshing with a rotor disposed between the poles is radially displaced from the center of the core to the side opposite the magnetic poles, whereby internal space of the ring-shaped core having a coil wound thereon is efficiently utilized for arranging all internal components substantially within dimensions of the coil and minimizing the entire size of the movement.
