Abstract: Various arrangements are disclosed based on springs formed from a plurality of individual resilient arms, including a spring having a substantially planar form in an unloaded state and rotational symmetry of at east order two about a symmetry axis perpendicular to the plane of the spring, the spring comprising: an inner hub and an outer hub, the inner hub being radially inward with respect to the outer hub; a plurality of resilient connecting arms each connected at an inner end to the inner hub and at an outer end to the outer hub, the plurality of resilient connecting arms being configured to provide a restoring force parallel to the symmetry axis when the inner and outer hubs are displaced relative to each other along the symmetry axis; wherein the inner hub, the outer hub and each of the plurality of resilient connecting arms are formed as physically separate elements and are connected to each other during assembly to form the spring.

Abstract: Various arrangements are disclosed based on springs formed from a plurality of individual resilient arms, including a spring having a substantially planar form in an unloaded state and rotational symmetry of at least order two about a symmetry axis perpendicular to the plane of the spring, said spring comprising: an inner hub and an outer hub, said inner hub being radially inward with respect to said outer hub; a plurality of resilient connecting arms each connected at an inner end to said inner hub and at an outer end to said outer hub, said plurality of resilient connecting arms being configured to provide a restoring force parallel to said symmetry axis when said inner and outer hubs are displaced relative to each other along said symmetry axis; wherein said inner hub, said outer hub and each of said plurality of resilient connecting arms are formed as physically separate elements and are connected to each other during assembly to form said spring.

Abstract: A moving coil transducer which comprises a yoke, permanent magnet and pole piece which are assembled to form a magnet circuit leaving an air gap between two opposing surfaces of the yoke and pole piece for receiving the moving coil. The permanent magnet is positioned between other opposing surfaces of the yoke and pole piece, and its faces are not parallel. Thus the thickness of the magnet increases away from the air gap of the magnetic circuit. In an annular or toroidal design in which the pole piece, permanent magnet and yoke are all annular and define an annular air gap, the magnet may be of conical form, having a thickness which increases away from the air gap. The pole piece and yoke are correpondingly tapered at the portions which meet the permanent magnet. The use of the non-flat magnet allows more magnetic material to be included in the transducer without increasing the overall volume of the transducer.