Abstract: A voice coil motor includes a fixing assembly and a moveable assembly. The fixing assembly includes a fixing frame and at least one magnet positioned on the fixing frame. The moveable assembly is movably received in the fixing assembly. The moveable assembly includes a moveable barrel. The moveable barrel includes a coil and resin filled in gaps of the coil. When the coil is powered on, the moveable barrel is capable of moving along an axis direction of the moveable barrel by a magnetic force generated by the at least one magnet.

Abstract: A voice coil motor (VCM) includes a lens carrier physically connected to a magnetic device, an electromagnetic driving apparatus, constructed by a coil, a magnetic sensing element, a storage media and a controller. The magnetic sensing element detects a location of the lens carrier and outputs the location value relating to the location of the lens carrier via an amplifier. The storage media stores a gain value and an offset compensation value relating to the amplifier. The controller can make the lens carrier move between a top position and a bottom position in which the lens carrier can be moved within the voice coil motor. The lens carrier is moved using the coil interaction with a magnetic field of the magnetic device when current is applied to the coil.

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: Provided are a lens driving motor and an elastic member of the lens driving motor. The elastic member of a lens driving motor, the elastic member includes a first spring and a second spring. The second spring is different from the first spring and disposed together with the first spring on one side of a carrier to support the carrier. A first lead line of a coil and a first external power source are connected to the first spring, and a second lead line of the coil and a second external power source are connected to the second spring to supply power to the coil. Since the carrier can be assembled to other part after a (+) lead line and a (?) lead line of the coil are connected to the first and second springs, respectively, using solder, a process is simple and convenient.

Abstract: An electrodynamic actuator (10), has a flat coil (24) formed by tracks (22, 23) on a face of a circuit board (16) and a permanent magnet (14) the magnetic field of which passes through turns of the flat coil (24).

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: A voice coil motor includes a stationary member, a moveable member, an upper resilient plate, and a lower resilient plate. The stationary member includes a receiving room and a magnetic unit. The magnetic unit consists of two magnets adhering to two sidewalls of the stationary member. The moveable member is received in the first receiving room and spaced from the stationary member. The moveable member includes a frame and coils wrapped around the frame. The coils face the magnets. The magnets and the coils cooperatively drive the moveable member to move upward from an initial position. The upper resilient plate and the lower resilient plate connect the stationary member with the moveable member. The two resilient plates provide a restoring force to drive the moveable member to return to the initial position.

Abstract: A linear motor includes an assembly of three magnets in series coaxially affixed inside of a housing, which results in an air gap therebetween, wherein the assembly includes a middle magnet whose direction of magnetization is opposite to that of the rest of the magnets. A first embodiment of the motor includes a coil carrier having a single electrical coil of two sections wound in the same direction and positioned into the corresponding two winding areas. The carrier is movably positioned into the air gap and further surrounds the assembly, thereby moving along an axial direction of the motor. A second embodiment includes two coils that are wound in a same direction with the respective separated wires and positioned into the respective two winding areas of the coil carrier.

Abstract: A voice coil motor (VCM) includes a moving unit, a fixing unit, an elastic plate, and a conducting pole. The moving unit includes a moving barrel and a coil assembly around the moving barrel. The coil assembly includes a connecting portion. The moving barrel defines a blind hole on an upper surface thereof, one end of a conducting pole being received in the blind hole. The fixing unit defines a through hole receiving the moving unit. The elastic plate is connected between the moving barrel and the fixing unit. The conducting pole provides a stable electrical connection between the elastic plate and the connecting portion notwithstanding movements of the moving barrel.

Abstract: A voice coil motor includes a case, a stationary module, and a movable module. The stationary module is retained within the case, and includes a housing and a number of magnets. The housing and the plurality of magnets are integrally formed. The movable module is movably retained within the case, and includes a barrel and a coil coupled to the barrel. When electric current is applied to the coil, the coil generates a magnetic field and the magnetic field repels the magnets, thereby driving the movable module to move.

Abstract: A voice coil motor (VCM) is disclosed, the VCM including: a stator including a magnet generating a first electromagnetic field; a mover including a bobbin formed with a hollow hole through which light passes and a coil formed on a periphery of the bobbin that generates a second electromagnetic field responsive to the first electromagnetic field; a base fixed at the stator and formed with an opening through which the light passes; and at least one elastic member elastically supporting the bobbin and forming a gap between the bobbin and the base when the coil is not applied with a current.

Abstract: A voice coil motor (VCM) includes a moving unit and a fixing unit, and the moving unit is movably received in the fixing unit. The moving unit includes a moving barrel, a first coil assembly, and a second coil assembly. The moving barrel includes a first outer surface. The first coil assembly is sleeved on the first outer surface. The second coil assembly includes four coils positioned at corners of the first outer surface. The fixing unit includes a fixing frame, a first magnet assembly, and a second magnet assembly. The first coil assembly is opposite to the first magnet assembly, and the second coil assembly is opposite to the second magnet assembly.

Abstract: A voice coil motor housing includes a top wall having an opening and four sidewalls extending from the top wall. The four sidewalls and the top wall cooperatively form a rectangular chamber opened at one end. Each of the sidewalls includes a top portion and a bottom portion. The top portions of the four sidewalls are connected to one another and forming a substantially gapless seam between each two adjacent sidewalls at the top portions. At least one slot is defined in the bottom portions of the sidewalls, the at least one slot is perpendicular to the top wall, and the slot is arranged adjacent to the corresponding gapless seam. At least one snap is arranged on the sidewalls at the corresponding bottom portion thereof, and the at least one snap protrudes inwardly of the chamber.

Abstract: A voice coil motor includes a lens retainer, a wire, and an elastic electrode member. The lens retainer includes an end portion. The wire wraps around the lens retainer and includes a first end and a second end. The elastic electrode member is metal and is mounted to the end portion. The elastic member includes a first elastic metal sheet and a second elastic metal sheet. The first elastic metal sheet includes a first electrode. The second elastic plate is physically separated from the first elastic sheet and includes a second electrode. The first end and the second end are respectively soldered to the first electrode and the second electrode.

Abstract: An actuator includes a bracket, permanent magnetic elements, a fixing barrel, and a movable unit. The actuator forms a central axis. The bracket includes a front frame and a rear frame connected with the front frame. Both the front frame and the rear frame include a supporting plate. Each supporting plate defines a through hole coaxial with the central axis. The permanent magnetic elements are positioned on supporting plates of the front and rear frames and surround through holes of the front and rear frames. The movable unit includes a hollow core member and a coil group wrapping around the core member. A height of the core member is smaller than that of the fixing barrel. The core member is movably received in the fixing barrel. The fixing barrel is housed in the bracket, and is sandwiched between the permanent magnetic elements.

Abstract: An exemplary voice coil motor includes a base, a stationary magnetic field generator, a moveable magnetic field generator, and a case. The base includes a first surface defining a number of cavities. The stationary magnetic field generator is mounted on the first surface, and includes a supporting frame defining a first receiving space. The moveable magnetic field generator is moveably received in the first receiving space, and includes a core member. The core includes a lower surface. A number of flanges extend downwards from the lower surface, and received in a respective one of the cavities. Each of the flanges includes an end surface that is away from the lower surface. The end surface defines two symmetrical sloped surfaces respectively extending slantingly downward from the middle of the end surface to two opposite sides of the flange. The case receives the stationary magnetic field generator, the moveable magnetic field generator.

Abstract: A voice coil motor (VCM) includes a shell, a frame, an elastic member, a moving unit, and a plurality of magnetic members. The shell includes a top plate and sidewall extending from the top plate. The frame is received in the shell and mounted to the top plate. The elastic member is mounted to the frame. The moving unit is received in the shell and includes a lens retainer and coils wrapped around the lens retainer. The frame and the elastic member are arranged on an end surface of the lens retainer. Each of the magnetic members is directly mounted to the sidewall and positioned between the sidewall and the moving unit.

Abstract: A voice coil motor includes a fixing assembly and a piston assembly movably received in the fixing assembly. The fixing assembly includes a fixing frame and one or more magnetic members positioned on the fixing frame. The piston assembly includes a lens and a coil sleeved on the lens. The coil and the lens cooperatively define a receiving groove. The fixing frame forms one or more resisting portions. The fixing frame sleeves on the lens with the resisting portions engaging in the receiving groove, such that the coil together with the lens is capable of moving along the at least one resisting portion utilizing the magnetic force generated by the magnetic members.

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 voice coil motor includes a stationary magnetic field generator having a supporting frame, a moveable magnetic field generator, a case and a double sided adhesive layer. The supporting frame defines a first receiving space receiving the moveable magnetic field generator. The moveable magnetic field generator defines a second receiving space. The case encloses the stationary magnetic field generator, the moveable magnetic field generator and the double sided adhesive layer and includes a bottom plate and side plates. The bottom plate includes a first surface and a second surface facing away the first surface. The side plates extend from the second surface. The bottom plate defines a through hole. A diameter of the through hole is smaller than that of the second receiving space. The double sided adhesive layer is entirely covering the second face.

Abstract: An electromagnetic vibrator includes an electromagnetic provider and a vibration unit, wherein the vibration unit includes a diaphragm unit and an induction coil unit affixing on an inner side of the diaphragm unit, so that when the vibration unit is mounted to the electromagnetic provider, the induction coil is inducted to the electromagnetic to generate an electromagnetic field, so as to axially vibrate the induction coil to vibrate the vibration unit.

Abstract: A VCM is disclosed, the VCM including a rotor including a bobbin arranged at an upper surface of a base formed with an opening, and a driving coil wound on the bobbin, a stator including a driving magnet opposite to the driving coil, and a yoke secured by the driving magnet at an inner surface of a lateral plate, and a tilting unit including a tilt magnet arranged at an outer surface of the lateral plate, a housing fixing the tilt magnet, and a tilt coil unit opposite to the tilt magnet.

Abstract: A voice coil motor (VCM) includes a case, a lens holder, a spring sheet, a coil, a magnet assembly, and a guiding ring. The case includes an inner surface. The lens holder is received in the case. The spring sheet is connected between the case and the lens holder. The coil circles around the lens holder. The magnet assembly is positioned on the inner surface of the case. The guiding ring defines a guiding hole and is positioned on the inner surface of the case, and one end of the lens holder is received in the guiding hole.

Abstract: A linear vibrator includes a casing defining an internal space of the vibrator, a bracket disposed under the casing and having a coil, to which electricity is applied to induce a magnetic field, an oscillator having a magnet received in a hollow portion of a yoke, one end of which is closed, and a cylindrical weight coupled onto the circumference of the yoke, and a spring member coupled with an upper portion of the casing to elastically support the oscillator such that the oscillator is movable in a linear motion, wherein the weight is provided with a plurality of circumferential recesses in which a rotary member is rotatably inserted while being in contact with a sidewall of the casing.

Abstract: A linear motor includes an assembly of two or more sets of magnets and pole pieces wherein the assembly is coaxially affixed inside of a housing, which results in an air gap therebetween. The magnets are positioned so that each magnet has opposite directions of magnetization relative to its adjacent magnet. The embodiment of the motor includes a coil carrier having a single electrical coil of two or more sections with each section wound in the opposite direction to the adjacent section and positioned into the corresponding winding areas of the carrier. The coil carrier is movably positioned into the air gap and further to surround the assembly, thereby moving along an axial direction of the motor when electricity is applied to the coil.

Abstract: The linear vibrator includes a base forming a hollow space, a suspension fixed on the base, and an oscillating portion suspended in the hollow space by the suspension. The suspension defines a flat part, a connecting portion bent downward from the flat part, and a spring portion extended horizontally in a direction parallel to flat part from the end of the connecting portion. The suspension is directly connected with the outside component, thereby transmitting the vibration to the outside component rapidly.

Abstract: An electromagnetic vibration device includes a vibrating plate, a suspending frame, upper and lower basin frames, a voice coil, and a magnetic loop system. Multiple voice coil fixing slots are uniformly distributed on the circumference of the vibrating plate corresponding to the inserting pieces of the voice coil, and the inserting pieces are passed through the voice coil fixing slots of the vibrating plate and fixed to the vibrating plate. One end of the lead of the voice coil is embedded in a groove on back of the vibrating plate and connected to the terminal of the lower basin frame.

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 viscoelastic body is interposed between a vibrating membrane vibrating in association with a piezoelectric vibrator composed of a piezoelectric element and a base and a support member supporting the vibrating membrane. The viscoelastic body attenuates vibration transmitted from the support member to the vibrating membrane and converts vibration of the vibrating membrane in the surface direction parallel to its main surfaces to vibration of the vibrating membrane in the direction nearly perpendicular to the surface direction. The vibrating membrane is annular with an opening at the center, and the base is joined to the vibrating membrane coaxially with opening.

Abstract: The present invention relates to an actuator apparatus of an active accelerator pedal, which can provide a driver with a pressing-force rise mode or a vibration mode in accordance with the operational condition of the accelerator pedal and the traveling condition of the vehicle; therefore, it is possible to improve fuel efficiency and also help safe traveling.

Abstract: A voice coil motor includes a housing, a movable barrel, at least two magnetic elements, and a coil received in the housing. The housing defines an accommodating room, and includes a top panel, at least two peripheral panels perpendicular to the top panel, and at least two fixing plates extending in the accommodating room. The at least two magnetic elements are surrounding the movable barrel. Each magnetic element has a first magnetic pole aligned with a corresponding fixing plate and a second magnetic pole fixed on the housing. The coil is sleeved on the movable barrel and is between the fixing plates and the first magnetic poles.

Abstract: A VCM is disclosed, the VCM including a bobbin formed with a coil at an outer surface thereof; at least one permanent magnet facing the coil formed at the bobbin; a cylindrical yoke encompassing the bobbin and the permanent magnet and including a metal member for blocking a magnetic field generated by the coil; a base coupled to the yoke; and an elastic member including a first elastic member interposed between the yoke and the permanent magnet for elastically supporting the bobbin and a second elastic member interposed between the base and the permanent magnet.

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: A flexible-printed-circuit (FPC) voice-coil assembly configured for integration in a voice-coil motor. The FPC voice-coil assembly includes at least one FPC voice coil. The FPC voice coil includes a coil including at least one coil turn, and a flexible substrate. The flexible substrate is coupled to the coil to form a flexible printed circuit. The FPC voice coil is configured for integration in a voice-coil motor. A voice-coil motor and a disk drive including the FPC voice-coil assembly are also provided.

Abstract: A voice coil motor (VCM) includes a case, a lower plate, a lens holder, a coil, a magnet assembly, and an elastic sheet. The case includes an upper plate and sidewalls extending from edges of the upper plate. Each sidewall includes an inner surface. The lower plate is positioned at one end of the sidewalls and opposite to the upper plate. The lens holder is received in the case. The coil is circled around the lens holder. The magnet assembly consists of a first magnet and a second magnet, the first magnet and the second magnet are plate shaped and respectively positioned on the inner surfaces of opposite two of the sidewalls. The elastic sheet is connected between the lower plate and the lens holder.

Abstract: The invention relates to an electromechanical conversion system comprising: a fixed supporting structure, a movable element with respect to the fixed structure; at least one excitation coil; and at least one permanent magnet for generating an excitation magnetic field. The permanent magnet is integral with the movable element and the coil is integral with the fixed supporting structure. Moreover, a ferromagnetic circuit is provided fixed with respect to the structure and cooperating with the permanent magnet.

Abstract: A voice coil motor housing includes a top wall having an opening and four sidewalls extending from the top wall. The four sidewalls and the top wall cooperatively form a rectangular chamber opened at one end. Each of the sidewalls includes a top portion and a bottom portion. The top portions of the four sidewalls are connected to one another and forming a substantially gapless seam between each two adjacent sidewalls at the top portions. At least one slot is defined in the bottom portions of the sidewalls, the at least one slot is perpendicular to the top wall, and the slot is arranged adjacent to the corresponding gapless seam. At least one snap is arranged on the sidewalls at the corresponding bottom portion thereof, and the at least one snap protrudes inwardly of the chamber.

Abstract: The disclosure relates to an electrodynamic-transducer magnetic motor device (10) having a moving coil comprising a magnetic circuit consisting of a tied angular magnet (11), characterized in that said tied annular magnet has a hollow annular structure, said hollow annular structure comprising an annular cavity (12) connected to an upper portion (13) of an external surface (14) of said hollow annular structure by a first annular channel (15) forming a first gap in which a first winding (17) of the moving coil can move.

Abstract: A voice coil motor includes a lens retainer, a wire, and an elastic electrode member. The lens retainer includes an end portion. The wire wraps around the lens retainer and includes a first end and a second end. The elastic electrode member is metal and is mounted to the end portion. The elastic member includes a first elastic metal sheet and a second elastic metal sheet. The first elastic metal sheet includes a first electrode. The second elastic plate is physically separated from the first elastic sheet and includes a second electrode. The first end and the second end are respectively soldered to the first electrode and the second electrode.

Abstract: A voice coil motor includes a movable receiving cylinder having protrusions formed at an end; a wire coil surrounding the receiving cylinder; a hollow fixing frame receiving the receiving cylinder and the wire coil; magnetic members fixedly received in the fixing frame, top and bottom elastic members. The top elastic member includes a peripheral portion and a resilient central portion, the central portion having a central opening and cutouts. The protrusions of the receiving cylinder are engaged in the cutouts. The peripheral portion is fixed at a lower position than the central portion, thereby forming an elastic force applied to the receiving cylinder when no current is applied to the wire coil. The bottom elastic member is connected to the receiving cylinder and the fixing frame, and is in an undeformed state when no current is applied to the wire coil.

Abstract: A voice coil motor (VCM) includes a fixed assembly and a movable assembly. The fixed assembly includes a fixed bracket and a coil group. The fixed bracket is substantially tri-columnar in shape and includes three sidewalls supporting the coil group thereon, and defines a first receiving cavity between the three sidewalls. The coil group is arranged on the three sidewalls. The movable assembly includes a movable barrel movably received in the first receiving cavity, and a magnet group. The movable barrel is also substantially tri-columnar in shape and includes three external surfaces. The magnet group is arranged on the three external surfaces of the movable barrel and spatially opposite to the coil group.

Abstract: An active eco pedal apparatus with an the actuator which includes a VCM having a pair of first and second coils through which a current flows in opposite directions, and a pair of first and second magnets interacting with the electric field generated by the pair of the first and second coils, in which additional repulsive force is generated from the VCM supplied by the current, in addition to basic moving forces, thereby increasing thrust to push a pedal and thus remarkably improving the efficiency of an eco mode, in which since the actuator is controlled in a single-phase manner by a single-phase driver chip without using a hall sensor having high error possibility, it is possible to improve the reliability of operation, and in which since the number of FETs is reduced, the system is configured to have a compact size, and costs are lowered.

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 VCM is disclosed, the VCM including a base formed with an opening; a bobbin arranged on an upper surface of the base and mounted with a lens therein; a plurality of magnets secured on the base to face a periphery of the bobbin; a coil block encompassing each magnet and the bobbin, and secured to a part of the bobbin exposed between the magnets; and a cover can encompassing the magnets and the coil block.

Abstract: A voice coil motor includes a stationary member, a moveable member, a base, and two guide posts. The stationary member includes a stationary frame and a number of magnets fixed on the stationary frame. The stationary frame defines a first receiving room. The moveable member is received in the first receiving room and includes a barrel holder and a coil. The barrel holder defines a second receiving room for receiving a lens barrel. The coil wraps around the barrel holder. Two through holes extend from a top surface to a bottom surface of the barrel holder. The base supports the stationary member and the moveable member. The guide posts are perpendicularly fixed on the base and pass through the through holes of the moveable 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 electromagnetic linear motor is proposed that features a longitudinal stator, a hollow body of the stator made of a magnetically soft material, a magnetic coil of the stator, a rotor in the stator that is movable linearly relative to the magnetic coil, an axially magnetized permanent magnet of the rotor and an axially variable shape or variable magnetic material properties of the stator.

Abstract: A reciprocating motor and a reciprocating compressor having the same are provided. One side of each of outer and inner cores forming a stator are connected to each other, to prevent a magnetic flux generated by the coil and a magnet from leaking out of the stator. Hence, it is possible to fabricate components of the reciprocating compressor employing such a reciprocating motor by using a relatively low-cost magnetic substance, resulting in a decrease in fabricating costs of the compressor. Also, a length of the magnet may be reduced, which results in a reduction of the cost for the magnet, thereby decreasing fabricating costs of the reciprocating motor and the reciprocating compressor employing the reciprocating motor.

Abstract: A lens actuator includes a housing, a loading plate, a moving unit, four magnetic elements, and an elastic plate. The housing and the loading plate cooperatively form an accommodating room. The housing includes a top panel having four fixing portions. The moving unit is movably received in the accommodating room. The four magnetic elements are received in the accommodating room around the moving unit, and are fixed on four inner sidewalls of the housing. The elastic plate is disposed between the top panel and the moving unit, and the four fixing portions of the housing firmly press the elastic plate on the four magnetic elements.

Abstract: A lens driving apparatus 1 of the present invention includes a substantially cylindrical yoke 3; a base 5 to which the yoke 3 is attached; a carrier 7 having a lens; a coil 10; and a magnet 13, wherein the carrier 7 is moved in a direction of an optical axis of a lens by electromagnetic force generated by passing current through the coil 10, the base 5 is substantially square-shaped as viewed from a plane, the yoke 3 is placed at an inner position of the base 5, the yoke 3 has an outer peripheral wall 3a and an annular inner peripheral wall 3b to be spaced to each other, each magnet is placed between the outer peripheral wall and the inner peripheral wall and at a position corresponding to a base corner portion of the base 5, and a space between the outer peripheral wall 3a and the inner peripheral wall 3b positioned at a base side portion 3e is made narrower than a space between the outer peripheral wall 3a and the inner peripheral wall 3b positioned at the base corner portion.