The disclosed device and method relate to an actuator. The actuator includes a field structure assembly having an arrangement of permanent magnets and magnetically soft components, and a moving coil assembly. The arrangement of permanent magnets includes a conical magnet and a plurality of segmented ring magnets.
1. An actuator comprising a field structure assembly comprising an arrangement of permanent magnets and magnetically soft components, and a moving coil assembly; wherein the arrangement of permanent magnets comprises a conical magnet and a plurality of ring magnet segments; a cylindrical field structure having a closed end and an open end wherein a magnetic assembly and a pole piece are provided inside the cylindrical field structure; wherein the pole piece includes a centrally-located hole, and wherein the pole piece receives a retaining screw in the centrally-located hole.
2. The actuator according to claim 1 , wherein the moving coil assembly comprises a cylindrical coil assembly having a closed end and an open end and comprising one or more terminals and a coil.
3. The actuator according to claim 1 , wherein an air gap is defined between a remaining portion of the outer surface of the pole piece and an inside surface of the open end of the field structure and wherein the open end of the coil assembly is operable to fit into the air gap between the outer surface of the pole piece and the inside surface of the open end of the field structure.
4. The actuator according to claim 1 , wherein the field structure assembly magnet is disposed at the closed end of the field structure.
5. The actuator according to claim 1 , wherein the conical magnet has an inclined circumferential face.
6. The actuator according to claim 1 , wherein an upper face of the conical magnet abuts a lower surface of the pole piece and a lower face of the conical magnet abuts an inward-facing surface of the closed end of the cylindrical field structure.
7. The actuator according to claim 1 , wherein each segmented ring magnet has an inner radial surface that abuts an outer surface of the cylindrical field structure and an outer radial surface that abuts an inner wall of the cylindrical field structure.
8. The actuator according to claim 5 , wherein each segmented ring magnet has an inclined lower surface that mates with the inclined circumferential face of the conical magnet.