Abstract: A fixing device includes a stationary frame and a number of elongated resilient tabs. The stationary frame defines a central axis and includes four sidewalls for receiving a number of magnets. Each sidewall includes a receiving hole and at least one protrusion formed on each sidewall at a lower portion thereof. A slot is defined in each protrusion. The tabs correspond to the magnets. Each tab includes an engagement portion, an angled portion, and a contact portion. The angled portion is interconnected between the engagement portion and the contact portion. The engagement portions engage in the respective slots. The contact portions resiliently abut against the corresponding magnets. Each tab is configured to apply a force on the corresponding magnet in a direction toward the central axis.

Abstract: A voice coil motor includes a stationary frame defining a first receiving space, a cover, and a base defining a second receiving space. The stationary frame includes a top surface and an opposite bottom surface. The top surface defines at least two first recesses. A first blocking portion is formed between each first recess and the first receiving space. At least two first protruding portions extend from the bottom surface. The cover is mounted to the top surface and includes a first surface facing the top surface. At least two second protruding portions extend from the first surface corresponding to the first recesses. The base supports the bottom surface and includes a second surface facing the bottom surface. The second surface defines at least two second recesses corresponding to the first protruding portions. A second blocking portion is formed between each second recess and the second receiving space.

Abstract: A voice coil motor includes a stationary member and a moveable member. The stationary member defines a central axis. The stationary member includes a first receiving room, four sidewalls surrounding the first receiving room and four guide rails formed on the respective sidewalls and located in the receiving room. The moveable member is received in the stationary frame. The moveable member includes a moveable frame. The moveable frame includes four side surfaces. A plurality of restricting posts extend from each side surface and are aligned in a line parallel to the corresponding guide rail. The restricting posts slidably engage in the corresponding guide rails.

Abstract: An acoustic exciter comprises a suspension made of an elastic material, which is coupled to the opening part of a frame, and a vibrator to which a voice coil disposed in the magnetic gap of a magnetic circuit connected to the suspension is coupled. An elastic body is so disposed between the frame and the vibrator as to be pressed against the frame and the vibrator. Thereby, the exciting efficiency of the vibrator can be increased, and the performance and tone quality of the acoustic exciter can be improved.

Abstract: A voice coil motor includes a stationary magnetic field generator a moveable magnetic field generator, and an elastic assembly. The stationary magnetic field generator includes a supporting frame and permanent magnetic elements mounted to peripheral sides of the supporting frame. The supporting frame has a first receiving space defined therein and includes first stopping portions formed in the first receiving space. The moveable magnetic field generator is moveably received in the first receiving space, and includes a core member and a coil wrapped around the core member. The core member includes second stopping portions. The second stopping portions are configured for engaging with the at least one first stopping portion to prevent the moveable magnetic field generator from rotating about a central axis of the core member. The elastic assembly elastically connects the moveable magnetic field generator and the stationary magnetic field generator.

Abstract: A multifunctional voice coil motor is disclosed, the motor including a rotor including a bobbin and a plurality of magnets arranged at a periphery of the bobbin, a stator including a housing wrapping each magnet and a plurality of coil blocks each arranged at a position corresponding to that of each magnet, a base coupled to the housing, and an elastic member elastically supporting the rotor.

Abstract: A voice coil motor type focusing actuator is disclosed to have a fixed unit, a movable unit and two resilient holding members. The fixed unit has a bracket with two slide shafts and a plurality of magnets mounted in the bracket. The movable unit has a lens holder movably mounted inside the bracket and a coil wound around the lens holder. The lens holder has two lugs. Each lug has a through hole for the slide shaft of the fixed unit to insert thereinto. The resilient holding member is fastened between the bracket of the fixed unit and the lens holder of the movable unit. When a current is supplied to the coil, a magnetic force is produced between the coil and the magnets to move the movable unit. When the current stops, an elastic force due to the resilient holding unit is utilized to pull the movable unit back to its original position.

Abstract: The invention relates to a method of making an actuator comprising a plurality of force elements and an actuator made according to the method. The method comprises providing a coupler for coupling force from the force elements to a load; calculating a transfer function for each force element wherein the transfer functions allow the force provided to the load to be predicted; determining an error functional which is indicative of any undesired dips in the predicted force; calculating the parameters of the force elements which minimise the error functional, and coupling force elements having the calculated parameters to the coupler to make the actuator.

Abstract: Methods and apparatus for increasing the efficiency of a voice coil motor (VCM) are disclosed. According to one aspect of the present invention, a cylindrical and radially symmetric VCM includes a plurality of sets of magnets, and a single coil. The plurality of sets of the magnets are each arranged in an array configuration, and cooperate to form a magnetic field. The coil receives current and has a plurality of windings. A first space is defined within the coil, and the plurality of sets of the magnets are arranged such that a first set of the magnets is positioned within the first space and a second set of the magnets is positioned external to the coil.

Abstract: A hard disk drive including a plurality of magnetic disks and a voice coil motor. The voice coil motor includes a coil and a first damper plate for dampening vibrations generated by the coil. The first damper plate is disposed within the voice coil motor.

Abstract: A magnetic head is controlled more stably when retracted from above a magnetic disk. When a permanent magnet member 10 having a protrusion projecting from the longer periphery to a side opposite to the center of a fan is mounted on a yoke 15, the end part P side where the sum of thicknesses (P1+P2) is the largest, i.e., the upper face side of a magnet matrix 111 on the protrusion side, is higher than the upper face side of the magnet matrix in the other area. Therefore, since the magnet matrix 111 in the protrusion is located closer to a lock pin 21, the magnetic attraction force between the lock pin 21 and the permanent magnet member 10 becomes stronger, so that the permanent magnet member 10 is locked more firmly when retracted from above the magnetic disk (at the time of locking), whereby the stability can be enhanced.

Abstract: A retaining member of a speaker motor may be formed using a mold. The mold may receive a plurality of speaker motor components. The mold may be configured to receive the speaker motor components in a desired arrangement. The mold may receive an injected material. The injected material may fill unoccupied space in the mold. The injected material may be cooled to form a retaining member to retain the speaker components in the desired arrangement subsequent to removal of the speaker motor components from the mold.

Abstract: An exemplary voice coil motor includes a fixed body, a movable barrel, a number of upper rollers, and a number of lower rollers. The fixed body includes a first receiving cavity, a number of upper recesses, and a number of lower recesses. The upper recesses and lower recesses are respectively arranged at opposite ends of the fixed body, and communicate with the first receiving cavity. The movable barrel is movably received in the first receiving cavity. The upper rollers are engagingly received in the corresponding upper recesses, and engage with the movable barrel for applying first friction forces to the movable barrel. The lower rollers are engagingly received in the lower recesses, and engage with the movable barrel for applying second friction forces to the movable barrel.

Abstract: A multi-layer armature for a moving armature receiver. The armature includes a first armature layer and a displacement region. The first armature layer includes a first surface and a second armature layer having a second surface positioned adjacent to the first surface. The displacement region provides relative displacement between the armature layers. The multi-layer construction of the armature in combination with the displacement region creates considerable design freedom in choosing armature geometry outside conventional bounds posed by the above-mentioned constraint between armature cross-sectional area and its mechanical stiffness. The design freedom can be applied to achieve numerous performance benefits for the moving armature receiver such as higher electroacoustic conversion efficiency, increased maximum sound pressure output or smaller overall length of the multi-layer armature.

Abstract: A voice coil motor includes a shell and a driving module in the shell. The shell includes a top plate. The driving module includes many magnets attached on the shell and defining a first receiving cavity, a movable unit movably received in the first receiving cavity, a bottom base, and a guiding post. The movable unit includes a movable barrel for receiving a lens module and a coil on the movable barrel. A central axis of the movable barrel is coaxial with an optical axis of the lens module. The movable barrel includes a first receiving portion. A central axis of the first receiving portion is parallel with the optical axis. The bottom base includes a second receiving portion. One end of the guiding post is received in the first receiving portion, and the other end of the guiding post is received in the second receiving portion.

Abstract: Disclosed is a voice coil motor, the motor including a rotor having a cylindrical bobbin that has a support block protruding from an upper end of an outer circumference thereof and a coil block that is coupled to the outer circumference of the bobbin in a direction from a lower surface to an upper surface of the bobbin and is supported by the support block, a stator having a magnet facing the coil block and a yoke holding the magnet, elastic members coupled to upper and lower surfaces of the bobbin, respectively, a base supporting the stator and the elastic members, and a foreign substance inflow-prevention portion formed on an upper surface of the base in such a way as to protrude around an opening formed in a central portion of the base in a shape of a closed loop.

Abstract: A magnetic circuit system includes a T-shaped yoke, a magnet, and a top plate. The top plate has a center hole, an internal end around the center hole thereof, and two projecting elements provided separately on upper surface and lower surface of the internal end, which improves non-linear distortion of a transducer using the magnetic circuit system.

Abstract: A voice coil motor includes a mount, a movable unit and a number of rollers. The mount includes a through hole, a number of recesses opposing the through hole, and a number of magnetic blocks mounted in the through hole. The movable unit includes a barrel and a coil of wire surrounding the barrel. The movable unit is movably received in the through hole of the frame and surrounded by the magnetic blocks. The rollers are rotatably received in the respective recesses and come in contact with the barrel. The rollers hold the movable unit in position when no magnetic force needed to be applied on the movable unit.

Abstract: A VCM (voice coil motor) is disclosed, the VCM including: a rotor including a lens-accommodating, both ends opened cylindrical bobbin and a coil block including a coil wound on a periphery of the bobbin; a stator including a cylindrical yoke formed with a lens-exposing opening, a plurality of magnets disposed inside the yoke and opposite to the coil block, and a magnet fixing member disposed inside the yoke to fix the plurality of magnets; and an elastic member elastically supporting the bobbin.

Abstract: Disclosed is a voice coil motor, the motor including a mover having a bobbin equipped with a lens and a coil block secured to an outer circumference of the bobbin; a stator having a magnet that is disposed in such a way as to face the coil block; elastic members coupled to a lower end of the bobbin and connected to both ends of the coil block; a base supporting the elastic members and the stator; and a cover can covering the mover, the stator and the base, with an opening being formed in the cover can to expose the lens therethrough, wherein each of the elastic members includes a terminal portion that extends between the cover can and a side surface of the base, the terminal portion including a short-circuit prevention portion so as to prevent a short-circuit between the terminal portion and the cover can.

Abstract: A VCM (voice coil motor) is disclosed, the VCM including: a rotor including a lens-fixing hollow holed bobbin including a coil discharge unit formed from a peripheral upper end to a peripheral bottom end facing the peripheral upper end, and a coil block arranged at a periphery of the bobbin and including a cylindrically wound coil; a stator including a magnet facing the coil block and a yoke fixing the magnet; a case including a bottom case arrange with the bobbin and an upper case coupled to the bottom case and having an opening at a portion corresponding the bobbin; and an elastic member elastically supporting an upper end of the bobbin and a bottom end facing the upper end of the bobbin, wherein a distal end of the coil arranged at an upper end of the coil block employs the coil discharge unit to be discharged to a bottom end of the bobbin.

Abstract: A linear motion control device for use in a linear control system is presented. The linear motion control device includes a coil driver to drive a coil that, when driven, effects a linear movement by a motion device having a magnet. The linear motion control device also includes a magnetic field sensor to detect a magnetic field associated with the linear movement and an interface to connect an output of the magnetic field sensor and an input of the coil driver to an external controller. The interface includes a feedback loop to relate the magnetic field sensor output signal to the coil driver input.

Abstract: A voice coil motor includes a base, a shell, first and second magnetic members, a lens retainer, a coil of wire mounted on the retainer, first and second elastic members. The base includes a bottom and posts extending upwards from the bottom. The shell includes a top and sidewalls cooperatively defining a receiving space therein. The shell is mounted on the base with the posts being received in the receiving space. The first magnetic members are positioned on the bottom of the base, the second magnetic members are positioned on the top of the shell, and each two adjacent of the posts have one of the first magnetic members and one of the second magnetic members located therebetween. The first resilient member and a second resilient member each include fixing portions fixed to the posts, and a spring portion connected to retainer between the first and second magnetic members.

Abstract: A voice coil motor is disclosed, the motor including: a mover including a bobbin including a first bobbin having a lens secured therein and a plurality of second bobbins intermittently protruded from an upper surface of the first bobbin, and a coil block secured to a periphery of the first bobbin; a stator including a magnet facing the coil block and a yoke securing the magnet; a case including a bottom case formed with the bobbin and an upper case coupled to the bottom case and having a portion that is correspondingly opened to the bobbin; and an elastic member elastically supporting the bobbin, wherein any one of the yoke and the upper case is formed with a rotation prevention unit extended to the plurality of second bobbins in order to prevent the bobbin from rotating.

Abstract: The invention relates to a moving part for an electro-dynamic transducer, including at least one mandrel supporting a winding of at least one coiled wire. The mandrel includes at least one first element rigidly connected inside at least one second element for guiding the moving part inside the transducer. The first element has a winding support for the coiled wire so that the coil is located inside the mandrel, as well as vibration transmitter, such as a diaphragm, the vibration being generated by the movement of the coil induced by the flow of current in the coil wire. The invention also relates to an electro-dynamic transducer including such a moving part.

Abstract: A spring plate includes a plate body having a through hole defined at the center thereof, and a terminal perpendicularly extending from the plate body. The plate body includes an outer closed-loop frame, an inner closed-loop frame, and spring parts interconnected between the outer closed-loop frame and the inner closed-loop frame. The terminal has an end portion distal from the plate body with at least one of a through hole and a recess therein.

Abstract: A voice coil motor includes a stationary frame defining a first receiving space, a cover, and a base defining a second receiving space. The stationary frame includes a top surface and an opposite bottom surface. The top surface defines at least two first recesses. A first blocking portion is formed between each first recess and the first receiving space. At least two first protruding portions extend from the bottom surface. The cover is mounted to the top surface and includes a first surface facing the top surface. At least two second protruding portions extend from the first surface corresponding to the first recesses. The base supports the bottom surface and includes a second surface facing the bottom surface. The second surface defines at least two second recesses corresponding to the first protruding portions. A second blocking portion is formed between each second recess and the second receiving space.

Abstract: A voice coil motor (VCM) is disclosed. The VCM includes a base formed with an opening; a movable body including a bobbin arranged on the base and formed with a hollow hole and a coil arranged along a periphery of the bobbin; a stator including a frame-shaped magnet arranged on the base, the magnet being discrete from the coil and wrapping a periphery of the coil; and a case covering an upper surface and an outer surface of the magnet, the case being coupled to the base.

Abstract: The invention relates to a magnetic actor in which the permanent magnets are arranged in a Halbach configuration and inserted into a slide-in frame.

Abstract: Disclosed is a voice coil motor, including a base having an opening, a stator is disposed on the base and including a magnet, a mover including a conductive coil opposing with the magnet, and a cylindrical bobbin in which a conductive coil is installed, a case fixed on the base and covering the stator, and a spacer intervened between the stator and the case and constituted with at least two spacers, each formed with different materials to absorb pressures and shocks transmitted to the stator from external.

Abstract: A shell for housing a voice coil motor (VCM) includes a casing and a cover. The casing defines a rectangular opening and two opening respectively in two opposite edges of the rectangular opening. The casing extends a pair of stripping strips into each opening and towards each other. The cover correspondingly defines two grooves. The cover covers the rectangular opening and each pair of gripping strip is bent into a corresponding groove to grip the cover.

Abstract: An acceleration generator 20 includes: a moving member (21, 25) that performs a periodic translational motion along a particular straight line; a first operating part (24) that applies a first force that varies in magnitude depending on the relative position thereof with respect to the moving member to the moving member in a direction parallel to the particular straight line; and a second operating part (27) that applies a second force that varies in magnitude depending on the relative position thereof with respect to the moving member to the moving member in a direction parallel to the particular straight line. The moving member performs a translational motion in which the acceleration thereof in the positive direction and the acceleration thereof in the negative direction are asymmetric in one period.

Abstract: A voice coil motor with a surface coil includes a set of magnetic sensing elements, a lens carrier physically connected to the set of magnetic sensing elements, a pedestal, and a set of printed circuit boards fixed onto the pedestal. A patterned metal layer is fabricated on the set of printed circuit boards to form the surface coil, a Hall sensor is installed on one of the printed circuit boards and transmits signals (e.g., operation voltages and feedback sensing signals) via traces fabricated on the set of printed circuit boards, so as to achieve simultaneous fabrication of the surface coil and traces, thereby saving space which is conventionally occupied by copper coils. The Hall sensor can sense a variation in a magnetic field resulting from the motion of the set of magnetic sensing elements to determine a motion status of the lens carrier.

Abstract: This invention provides a linear motor at least including an electrically controlled actuator and an elastic member. The electrically controlled actuator at least comprises a fixed element, a movable element, and an electrical unit, and at least provides an axial displacement. The elastic member at least comprises a fixed portion, a movable portion, an elastic portion, and a pair of power supply terminals. The fixed portion of the elastic member is connected to the fixed element of the actuator. The movable portion of the elastic member is connected to the movable element of the actuator. Various portions of the elastic member have different thicknesses depending on desired stiffness of each portion, such that the elastic member can be thinned to facilitate miniaturization of the linear motor. The needs to have an elastic member with desired stiffness and to provide good electrical contact are both met by the present linear motor.

Abstract: A plate spring includes holding section, first attached section, second attached section, first spring section connected between the holding section and the second attached section, and a second spring section connected between the first fixed portion and the second fixed portion. The holding section has a first edge, second edge opposite to the first edge, and a third edge. The first attached section is positioned adjacent to an intersection of the third edge and the second edge. The second attached section is positioned adjacent to an intersection of the third edge and the first edge. The first spring section has a wavy configuration and extends from an end of the first edge to the second attached section. The second spring section also has a wavy configuration and extends from an end of the second to the first attached section. The present disclosure also provides a voice coil motor.

Abstract: A voice coil motor type focusing actuator, which includes a fixed unit, the fixed unit comprises a bracket which is formed by plastic injection molding to wrap a metal part, and a plurality of magnets mounted in the bracket at a plurality of sides. A movable unit, the movable unit comprises a lens holder movably mounted inside the bracket and a coil mounted on a plurality of sides of the lens holder corresponding to the magnets. And a resilient holding unit connected between the fixed unit and the movable unit to hold down the movable unit on the fixed unit.

Abstract: A linear electromagnetic machine is described which comprises first and second substantially cylindrical parts arranged to move relative to each other along a common axis of motion. The first cylindrical part produces a spatially periodic radial magnetic field across an air gap, the magnetic field having a regular alternating polarity along or parallel to the axis of motion. The second cylindrical part comprises a plurality of laminar electrical conductors wrapped into cylindrical form and placed in the air gap to intercept the magnetic field, each of the laminar electrical conductors compromising a regular pattern of electrically conductive paths, the electrically conductive paths of the plurality of laminar electrical conductors being interdigitated together within the air gap.

Abstract: A voice coil motor includes a base, a shell, first and second magnetic members, a lens retainer, a coil of wire mounted on the retainer, first and second elastic members. The base includes a bottom and posts extending upwards from the bottom. The shell includes a top and sidewalls cooperatively defining a receiving space therein. The shell is mounted on the base with the posts being received in the receiving space. The first magnetic members are positioned on the bottom of the base, the second magnetic members are positioned on the top of the shell, and each two adjacent of the posts have one of the first magnetic members and one of the second magnetic members located therebetween. The first resilient member and a second resilient member each include fixing portions fixed to the posts, and a spring portion connected to retainer between the first and second magnetic members.

Abstract: Voice coil motor includes a housing shell, a fixing member, a movable member and elastic members. The fixing member includes a bracket and a number of first magnetic members retained on the bracket. The movable member includes a retainer and a number of second magnetic members mounted thereon. One of the first or the second magnetic member includes a first permanent magnet and a second permanent magnet abutting against the first permanent magnet, with each of the first and second permanent magnets including an N polarity side and an S polarity side. A pair of the first and second permanent magnets facing the same other one of the first and second magnetic members with only the N polarity side of the first permanent magnet and only the S polarity side of the second permanent magnet facing the same the other one of the first and second magnetic member.

Abstract: A voice coil motor assembly includes a housing, a voice coil motor, a cover, and a transparent board. The voice coil motor is received in the housing. The cover is secured to the voice coil motor and resists the top surface of the housing. The cover includes a top surface defining an aperture. A limiting element protrudes from the top surface of the cover. The transparent board is adhered to the top surface of the cover and covers the aperture. The movement of the transparent board is limited by the limiting element.

Abstract: An acceleration generator 20 includes: a moving member (21, 25) that performs a periodic translational motion along a particular straight line; a first operating part (24) that applies a first force that varies in magnitude depending on the relative position thereof with respect to the moving member to the moving member in a direction parallel to the particular straight line; and a second operating part (27) that applies a second force that varies in magnitude depending on the relative position thereof with respect to the moving member to the moving member in a direction parallel to the particular straight line. The moving member performs a translational motion in which the acceleration thereof in the positive direction and the acceleration thereof in the negative direction are asymmetric in one period.

Abstract: A camera module includes a rear lens barrel, a front lens barrel assembled to the rear lens barrel, the front lens barrel and the rear lens barrel together forming a housing space, a lens holder that holds an imaging optical system and is housed in the housing space, a guiding mechanism that movably supports the lens holder along the optical axis of the imaging optical system, and a driving unit that moves the lens holder along the optical axis of the imaging optical system, the driving unit including a magnet provided in the lens holder and a coil that faces the magnet. The rear lens barrel has a bottom wall that faces the housing space. The coil includes first and second coils disposed in the rear lens barrel on opposite sides of the optical axis in the housing space.

Abstract: The present invention relates to an oscillator, particularly for or in a flat loudspeaker, particularly for use in the aerospace field, comprising an oscillating part carrier, a coupling ring for coupling the oscillator to a sound converter of a loudspeaker, wherein the oscillating part carrier and the coupling ring are connected to each other via a detachable quick-release closure, comprising first closing elements for a locked, secure connection in relation to vibrations and second closing elements that are separate from the first closing elements, for a secure connection between the oscillating part carrier and the coupling ring. The invention further relates to a flat loudspeaker comprising such an oscillator and to a vehicle comprising such a flat loudspeaker.

Abstract: The permanent magnet member 10 for a voice coil motor (VCM) in accordance with the present invention comprises a magnet body 1 including a shorter periphery 11, a longer periphery 12 located at a position separated from the shorter periphery 11 by a predetermined distance, and a pair of side peripheries 13, 14 connecting the shorter periphery 11 and longer periphery 12 to each other, the magnet body having a fan-shaped planar form; and a corrosion-resistant film (Ni plating film 2) applied to a surface of the magnet body. The permanent magnet member 10 has a thickness whose maximum and minimum values yield a difference of 10 to 150 ?m therebetween.

Abstract: A direct current motor comprises a magnet assembly having a pair of magnets for generating a magnetic field and a coil assembly located between the pair of magnets, the coil assembly and the magnet assembly being movable relative to each other. The coil assembly further comprises a first coil section and a second coil section which are electrically connected to each other. A current generator is electrically connected to the coil assembly and is operative to provide first, second and third currents that are out of phase with respect to one another. The first current is electrically connected directly to the first coil section and the second current is electrically connected directly to the second coil section whereas the third current is electrically connected to the first and second coil sections at a position connecting the first and second coil sections.

Abstract: An exemplary voice coil motor includes a hollow stationary magnetic field generator, a movable magnetic field generator, two elastic members, a hollow case and a base. The movable magnetic field generator is received in the stationary magnetic field generator. The two elastic members are adjacent to two ends of the stationary magnetic field generator. The case and the base serve as a package for all of the above elements. The case has a top sheet. The movable magnetic field generator has guiding posts slidably received in the top sheet, and stopping bars. The stopping bars of the movable magnetic field generator are capable of limiting the movement of the movable magnetic field generator toward the top sheet by abutting the top sheet.

Abstract: A magnetic circuit system includes a T-shaped yoke, a magnet, and a top plate. The top plate has a centre hole, an internal end around the centre hole thereof, and two projecting elements provided separately on upper surface and lower surface of the internal end, which improves non-linear distortion of a transducer using the magnetic circuit system.

Abstract: A shell for housing a voice coil motor (VCM) includes a casing and a cover. The casing defines a rectangular opening and two opening respectively in two opposite edges of the rectangular opening. The casing extends a pair of stripping strips into each opening and towards each other. The cover correspondingly defines two grooves. The cover covers the rectangular opening and each pair of gripping strip is bent into a corresponding groove to grip the cover.

Abstract: A voice coil motor includes a stationary magnetic field generator a moveable magnetic field generator, and an elastic assembly. The stationary magnetic field generator includes a supporting frame and permanent magnetic elements mounted to peripheral sides of the supporting frame. The supporting frame has a first receiving space defined therein and includes first stopping portions formed in the first receiving space. The moveable magnetic field generator is moveably received in the first receiving space, and includes a core member and a coil wrapped around the core member. The core member includes second stopping portions. The second stopping portions are configured for engaging with the at least one first stopping portion to prevent the moveable magnetic field generator from rotating about a central axis of the core member. The elastic assembly elastically connects the moveable magnetic field generator and the stationary magnetic field generator.

Abstract: A magnetic circuit includes a cylindrical yoke member having an inner circumferential surface and a collar formed at one end thereof and turned back substantially at right angles, and a plurality of permanent magnet segments of a partially circular arc in cross section. Each of the permanent magnets has an outer surface attracted magnetically to the inner circumferential surface of the cylindrical yoke member, and one end face attracted magnetically to the collar of the cylindrical yoke member. The magnetic circuit is applied to an actuator or a speaker.