Patent Publication Number: US-11031856-B2

Title: Vibration actuator

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is entitled to (or claims) the benefit of Japanese Patent Application No. 2018-035773, filed on Feb. 28, 2018, the disclosure of which including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a vibration actuator. 
     BACKGROUND ART 
     In the related art, a vibration actuator, which is a vibration generation source, is mounted on a mobile device having a vibration function. By driving the vibration actuator to transmit vibration to a user, the user can be notified of an incoming call, or feeling of operation or sensation of reality can be improved. Herein, the mobile device includes a mobile communication terminal such as a mobile phone and a smart phone, a mobile information terminal such as a tablet PC, a mobile game terminal, a stationary game machine controller (a game pad), and a wearable terminal attached to clothes and an arm. 
     As a miniaturized vibration actuator, for example, a vibration actuator used in a pager or the like is known, as disclosed in PTL 1. 
     In the vibration actuator, a pair of plate-shaped elastic bodies is supported by a frame to oppose each other, and a yoke to which a magnet is attached is fixed and supported by a risen middle part of one plate-shaped elastic body having a spiral shape. The yoke configures a magnetic field generator with the magnet, a coil attached to the other plate-shaped elastic body is disposed in the magnetic field generator. A current having a different frequency is switched and applied to the coil through an oscillation circuit, and the pair of plate-shaped elastic bodies is selectively resonated to generate vibration. Consequently, the yoke vibrates in a center axis direction of the frame. 
     CITATION LIST 
     Patent Literature 
     PTL 1 
     Japanese Patent Application Laid-Open No. 10-117472 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, since the mobile device having a vibration function is required to give a user sufficient vibration that is actually felt, there is a call for a vibration actuator which is assembled with a simpler configuration than that of the vibration actuator disclosed in PTL 1, as a vibration actuator that gives stronger vibration. 
     An object of the present invention is to provide a vibration actuator that is easily assembled with a simple configuration and can realize desired vibration output. 
     Solution to Problem 
     In order to achieve the object mentioned above, the present invention provides a vibration actuator, including: a movable body including one of a coil and a magnet disposed on a radially inner side of the coil while being spaced from the coil; a fixing body including the other one of the coil and the magnet; and an elastic support portion supporting the movable body in such a way that the movable body is freely movable with respect to the fixing body, in which the movable body vibrates with respect to the fixing body in a magnetization direction of the magnet in cooperation with the coil to which power is supplied and the magnet, in which: the fixing body includes: a first fixing body disposed on one side of a vibration direction so as to cover the movable body, and a second fixing body that is disposed on a side of the other one of the vibration direction so as to cover the movable body, the second fixing body being bonded to the first fixing body and being configured to accommodate the movable body in such a way that the movable body is capable of vibrating, in which: the elastic support portion is a plate-shaped elastic body that includes one end portion fixed to the movable body and is provided to protrude from an outer periphery of the movable body in a radial direction, and another end portion of the elastic support portion is fixed while being sandwiched between the first fixing body and the second fixing body. 
     Advantageous Effects of Invention 
     According to the present invention, assembly is easy with a simple configuration and desired vibration output can be realized. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a vibration actuator according to an embodiment of the present invention; 
         FIG. 2  is bottom surface side perspective view of the vibration actuator; 
         FIG. 3  is a schematic sectional view illustrating a configuration of important portions of the vibration actuator; 
         FIG. 4  is an upper surface side exploded view illustrating a fixing body and a movable body in the vibration actuator; 
         FIG. 5  is a bottom surface side exploded view illustrating the fixing body and the movable body in the vibration actuator; 
         FIG. 6  is an upper surface side exploded perspective view of an upper fixing body of the vibration actuator; 
         FIG. 7  is a bottom surface side exploded perspective view of the upper fixing body of the vibration actuator; 
         FIG. 8  is an upper surface side exploded perspective view of a lower fixing body of the vibration actuator; 
         FIG. 9  is a bottom surface side exploded perspective view of the lower fixing body of the vibration actuator; 
         FIG. 10  is an upper surface side exploded perspective view of a movable unit of the vibration actuator; 
         FIG. 11  is a bottom surface side exploded perspective view of the movable unit of the vibration actuator; 
         FIG. 12  is a perspective view illustrating a bonding portion between an elastic support portion and a ring core of the movable body; 
         FIG. 13A  is a view illustrating a state where an annular inner peripheral bonding portion is fitted in a bonded end portion of the ring core; 
         FIG. 13B  is a view illustrating a state where the annular inner peripheral bonding portion is bonded to the ring core; and 
         FIG. 14  is a sectional view illustrating a magnetic circuit configuration of the vibration actuator. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 
       FIG. 1  is a perspective view illustrating vibration actuator  10  according to Embodiment of the present invention,  FIG. 2  is a bottom surface side perspective view of this vibration actuator  10 , and  FIG. 3  is a schematic sectional view illustrating a configuration of important portions of this vibration actuator  10 . In addition,  FIGS. 4 and 5  are an upper surface side exploded view and a bottom surface side exploded view, both of which illustrate fixing body  20  and movable body  60  in this vibration actuator  10 . An “upper” side and a “lower” side in Embodiment are given for convenience of description in order to facilitate understanding, and respectively mean one direction and the other direction of a vibration direction of movable body  60  (refer to  FIG. 3 ) in vibration actuator  10 . That is, when mounting vibration actuator  10  onto a device, the upper side and the lower side may be reversed or may be the right and the left. 
     Vibration actuator  10  illustrated in  FIGS. 1 and 2  is mounted as a vibration generation source onto a mobile device such as a smart phone, and realizes a vibration function of the mobile device. Vibration actuator  10  is driven, for example, in a case of notifying a user of an incoming call or giving feeling of operation or sensation of reality. 
     Vibration actuator  10  illustrated in  FIGS. 1 to 5  has movable body  60  that is disposed to freely reciprocate via elastic support portion  50  in case  32  of fixing body  20 , elastic support portion  50 , and fixing body  20 . Vibration actuator  10  has a magnetic circuit configuration that causes movable body  60  to oscillate in cooperation with coil  48  and magnet  65  by coil  48  being electrically connected to a power supply section (not illustrated). 
     Although vibration actuator  10  of Embodiment has a so-called moving magnet type configuration where coil  48  is provided on a fixing body  20  side and magnet  65  is provided on a movable body  60  side, the invention is not limited thereto. A moving coil type configuration where coil  48  is provided in movable body  60  may be adopted. 
     Fixing body  20  of vibration actuator  10  has two units (upper fixing body  30  and lower fixing body  40 ), and movable body  60  and elastic support portion  50  are set as one movable unit  70 . By assembling the three units into one, vibration actuator  10  is easily formed. 
     Fixing body  20  supports movable body  60  of movable unit  70  to be movable in a magnetization direction (which also corresponds to a coil axis direction in Embodiment), which is a sandwiched direction at this time, by the other end portion of elastic support portion  50  of movable unit  70  (outer peripheral bonding portion  502  illustrated in  FIG. 12 ) being sandwiched between upper fixing body (first fixing body)  30  and lower fixing body (second fixing body)  40 . The sandwiched direction corresponds to the vibration direction of movable body  60  in vibration actuator  10 . In addition, elastic support portion  50  is a plate-shaped elastic body, and is a plate spring in Embodiment. Elastic support portion  50  has one end fixed to movable body  60 , and is disposed in a radial direction from an outer periphery of movable body  60 . Details of elastic support portion  50  will be described later. 
     &lt;Upper Fixing Body  30 &gt; 
       FIGS. 6 and 7  are an upper surface side exploded perspective view and a bottom surface side exploded perspective view of upper fixing body  30  of vibration actuator  10  according to Embodiment of the present invention. 
     Upper fixing body  30  is disposed on one side of the vibration direction to cover movable body  60 . 
     As illustrated in  FIGS. 3, 6, and 7 , upper fixing body  30  has case  32 , upper spring fixing portion  34 , shaft  36 , and shock absorbing member  38 . 
     Case  32  configures an appearance of vibration actuator  10 , and accommodates movable body  60  therein. 
     In Embodiment, case  32  configures a hollow cylindrical appearance with base plate  42  of lower fixing body  40 , and accommodates movable unit  70 , that is, elastic support portion  50  and movable body  60  therein. 
     Case  32  is configured of a metal material such as stainless steel (SUS) having shock resistance. Case  32  may be a metal plate molded in a recessed shape through drawing. Case  32  is preferably configured of a metal that is the same type as base plate  42  (for example, stainless steel (SUS) 304). 
     Case  32  has cylindrical peripheral wall portion  324  that hangs from an outer periphery of disk-shaped upper surface portion  322 , and is engaged and fixed to an outer peripheral edge of base plate  42  by means of protruding claw portion  3241  provided at a lower end portion of peripheral wall portion  324 . Claw portion  3241  is fixed to the outer peripheral edge of base plate  42  through swaging or welding, or through both of swaging and welding. Since case  32  and base plate  42  are configured of the same type of metal, the case and the base plate can be firmly fixed through swaging or welding in Embodiment. In particular, in a case of fixing through welding, melting points of both of case  32  and base plate  42  are the same. Thus, both can be more firmly fixed. Case  32  may be a magnetic body, or may be a magnetized body. 
     On the same axis as coil  48 , shaft  36  is suspended in the middle of upper surface portion  322  of case  32 . 
     Movable body  60  is configured to move along shaft  36 . One end portion (an upper end portion, in Embodiment) of the shaft is fixed to upper surface portion  322 , and the other end portion thereof is fixed to base plate  42  of lower fixing body  40 . 
     Shaft  36  is fixed to each of upper surface portion  322  and base plate  42  through any bonding method such as adhesion, welding, and press-fitting. In Embodiment, shaft  36  may be fixed by being inserted into an opening portion formed in each of upper surface portion  322  and base plate  42  through any of adhesion, welding, and press-fitting, or at least two bonding methods. In addition, although shaft  36  is fixed to upper fixing body  30  in  FIGS. 4 to 7 , the shaft may be fixed to base plate  42  on a lower fixing body  40  side. 
     In case  32 , one end portion (upper abutment portion  342 ) of upper spring fixing portion  34  abuts against elastic support portion  50  of movable unit  70  from an upper side of the vibration direction of movable body  60 , and the other end side thereof is in contact with upper surface portion  322 . 
     Specifically, upper spring fixing portion  34  is disposed on an inner peripheral surface of peripheral wall portion  324 , and abuts against and presses outer peripheral bonding portion  502  by means of upper abutment portion  342 . Outer peripheral bonding portion  502  is sandwiched and fixed between upper abutment portion  342  and coil holder (lower spring fixing portion)  44  of lower fixing body  40 . Outer peripheral bonding portion  502  configures an outer peripheral edge of elastic support portion  50  as the other end portion of elastic support portion  50  of movable unit  70 . 
     In addition, a plurality of protruding deflection portions  344  which are plastically deformable or elastically deformable are provided on the other end portion (upper end portion) of upper spring fixing portion  34 , and the upper spring fixing portion abuts against upper surface portion  322  by means of deflection portions  344 . When pressed in a direction where elastic support portion  50  is sandwiched between upper spring fixing portion  34  and coil holder  44 , deflection portions  344  abut against a movable body accommodated side of upper surface portion  322  of case  32  and then deflect. Accordingly, the position of upper spring fixing portion  34  can be adjusted between upper surface portion  322  and elastic support portion  50  in case  32 . That is, deflection portions  344  make the adjustment of a height dimension of upper spring fixing portion  34  that presses elastic support portion  50  possible. 
     In Embodiment, upper spring fixing portion  34  is formed of a deformable resin material. Between case  32  and base plate  42 , elastic support portion  50  is reliably sandwiched between coil holder  44  and the upper spring fixing portion. 
     Shock absorbing member  38  is disposed between movable body  60  that moves and upper surface portion  322  of case  32 , and comes into contact with movable body  60  at the time of a maximum amplitude of movable body  60 . Shock absorbing member  38  is, for example, a damper formed of a sponge or the like, is formed in a ring shape, and is attached to the movable body accommodated side of upper surface portion  322  in a state where shaft  36  is inserted, in Embodiment. In a case where a movable amplitude of movable body  60  in vibration actuator  10  has increased, or when an external shock is applied, shock absorbing member  38  prevents a strange noise from occurring or each component from being damaged by a shock as a result of movable body  60  coming into contact with case  32 . 
     &lt;Lower Fixing Body  40 &gt; 
       FIGS. 8 and 9  are an upper surface side exploded perspective view and a bottom surface side exploded perspective view of lower fixing body  40  of vibration actuator  10  according to Embodiment of the present invention. 
     Lower fixing body  40  is disposed on the other side (the lower side) of the vibration direction to cover movable body  60 , and accommodates movable body  60  to be capable of vibrating by being bonded to upper fixing body  30 . 
     In Embodiment, tubular coil  48  configuring the magnetic circuit with magnet  65  is provided in lower fixing body  40 . 
     In addition to coil  48 , lower fixing body  40  has base plate  42 , coil holder  44 , and shock absorbing member  46 . 
     Base plate  42  configures a bottom surface portion of vibration actuator  10 . Base plate  42  configures a housing of vibration actuator  10  with case  32 . 
     Base plate  42  is formed in a disk shape corresponding to the shape of case  32 , that is, the shape of an opening of peripheral wall portion  324  in case  32 , and has a disk-shaped base main body part opposing upper surface portion  322 . Protruding plate portion  422  which protrudes radially outward from a part of an outer periphery of the base main body part is provided. 
     Base plate  42  is configured of a metal material such as stainless steel (SUS) having shock resistance, and an engaged portion which is engaged with the lower end portion of peripheral wall portion  324  of case  32  is formed on an outer peripheral edge portion thereof. The lower end portion of peripheral wall portion  324  of case  32  is fixed to the engaged portion through one or both of swaging and welding. In Embodiment, base plate  42  is configured of the same type of metal (for example, stainless steel (SUS) 304) as case  32  as described above, and has a structure of being fixed to case  32  and being able to withstand internal vibration of movable body  60 . 
     Coil  48  is provided on base plate  42  via coil holder  44 . 
     Coil holder  44  holds coil  48 , and magnet  65  is positioned on the same axis with a predetermined interval placed on a radially inner side of coil  48 . 
     In addition, coil holder  44  abuts against elastic support portion  50  on the lower side, and functions as the lower spring fixing portion that causes elastic support portion  50  to be sandwiched between upper spring fixing portion  34  and the coil holder. 
     Coil holder  44  is a nonmagnetic body interposed between coil  48  and base plate  42 . In addition, coil holder  44  is preferably configured of a nonconductive material such as a resin. 
     Accordingly, a configuration where coil holder (nonconductive portion)  44  made of a nonconductive material is disposed between base plate  42  and coil  48  is adopted. Coil  48  can be fixed to coil holder  44  in an electrically insulated state when assembling coil  48  into fixing body  20 . In addition, even when coil holder  44  is a resin component and has a bobbin structure, ease of assembly can be achieved. 
     Coil holder  44  has disk-shaped holder main body  442 , lower abutment portion  444  that abuts against elastic support portion  50 , and leading portion  446  that leads wiring connected to coil  48 . 
     Holder main body  442  has an outer diameter that is substantially the same as an inner diameter of case  32 , and is formed in a disk shape to be inserted into case  32 . Holder main body  442  is attached onto the base main body part of base plate  42 . A coil fixing portion having a recessed shape to which coil  48  is fixed is provided in holder main body  442 , and coil  48  is fixed to the coil fixing portion through adhesion or the like. In addition, shaft  36  to be inserted into an opening portion formed in a middle portion is fixed to holder main body  442 . 
     Lower abutment portion  444  abuts against elastic support portion  50 , and is provided to rise from an outer peripheral edge portion of holder main body  442 . Herein, lower abutment portion  444  is formed in an annular peripheral wall shape. Accordingly, elastic support portion  50  is fixed to fixing body  20  at a position of separating away from holder main body  442 . An interval between elastic support portion  50  (specifically, outer side bonding portion  502  of elastic support portion  50 ) and holder main body  442  is a movable range from a normal position of movable body  60  to the other side of the vibration direction. 
     Leading portion  446  leads the wiring connected to coil  48 . Leading portion  446  is provided to protrude from one end portion of holder main body  442 , and is disposed on protruding plate portion  422  of base plate  42 . External power is supplied to coil  48  via the wiring of leading portion  446 . 
     Coil holder  44  and base plate  42  overlap each other in a positioned state where a plurality of sets of positioning protrusion portions  448  and positioning recessed portions  428 , which are respectively provided therein, are fitted to each other. For example, coil holder  44  is molded as a nonmagnetic body made of a resin which is a nonconductive material, and positioning recessed portions  428  of metal base plate  42  are through-holes, in Embodiment. Accordingly, positioning protrusion portions  448  on a coil holder  44  side are inserted and fitted to the through-holes which are positioning recessed portions  428 , and inserted resin positioning protrusion portions  448  are melted and thereby can be easily fixed to the through-holes. 
     Shock absorbing member  46  is disposed between movable body  60  that moves and holder main body  442  of coil holder  44 , and comes into contact with movable body  60  at the time of a maximum amplitude of movable body  60 . The shock absorbing member is, for example, a damper formed of a sponge or the like, is formed in a ring shape, and is attached onto holder main body  442  in a state where shaft  36  is inserted, in Embodiment. In a case where a movable amplitude of movable body  60  in vibration actuator  10  has increased, or when an external shock is applied, shock absorbing member  46  prevents a strange noise from occurring or each component from being damaged by a shock as a result of movable body  60  coming into contact with base plate  42 . 
     In assembled vibration actuator  10 , coil  48  is used in generating a drive source of vibration actuator  10  with magnet  65  with an axial direction thereof (the magnetization direction of magnet  65 ) as the vibration direction. An axis of coil  48  is, for example, disposed on the same axis as at least the axis of magnet  65 , out of those of magnet  65  and shaft  36  to be described later. 
     Both end portions of coil  48  are wired to leading portion  446 , and are connected to the power supply section (not illustrated). Herein, both end portions of coil  48  wired to leading portion  446  are connected to an alternating current power supply section, and alternating current power (alternating current voltage) is supplied to coil  48  from the alternating current power supply section. Accordingly, thrust that allows coil  48  and the magnet to move with respect to each other in the axial directions of each other, that is, in a contact/separation direction can be generated. Specifically, an upper end portion of coil  48  is disposed to oppose a center part of magnet  65  on the radially inner side in the axial direction, and a center part of coil  48  in the axial direction is disposed to oppose center yoke  63 . In a case where magnetization has occurred such that a flat plate core  614  side (the upper side, in Embodiment) and a center yoke  63  side of magnet  65  become an S-pole and an N-pole respectively, a magnetic flux, which is radiated from a bonding part between magnet  65  and center yoke  63  and is incident from the flat plate core  614  side, is formed. Therefore, the magnetic flux crosses from the radially inner side to the outer side of coil  48  with respect to any part of coil  48  disposed to surround magnet  65  and center yoke  63 . Thus, the Lorentz force acts in the same direction (an F-direction or a −F-direction shown in  FIG. 14 ) when electrically connected to coil  48 . 
     &lt;Movable Unit  70 &gt; 
       FIGS. 10 and 11  are an upper surface side exploded perspective view and a bottom surface side exploded perspective view of movable unit  70  of vibration actuator  10  according to Embodiment of the present invention. 
     Movable unit  70  has one of coil  48  and magnet  65 . In Embodiment, movable unit  70  has magnet  65 . 
     Movable unit  70  is supported by elastic support portion  50  to be able to reciprocate between upper surface portion  322  and base plate  42  in a direction where upper surface portion  322  and base plate  42  oppose each other, in case  32  and base plate  42  of fixing body  20 . 
     Movable unit  70  is provided such that elastic support portion  50  radially projects from the outer periphery of movable body  60  formed in a disk shape, and an outer peripheral portion (outer peripheral bonding portion  502 ) of projecting elastic support portion  50  is fixed to fixing body  20  by being sandwiched between upper spring fixing portion  34  and coil holder  44 . 
     In movable unit  70 , elastic support portion  50  is fixed to an end portion of movable body  60  on the lower side (a coil  48  side). 
     Movable body  60  has movable portion core  61 , center yoke  63 , lower bearing  64 , magnet  65 , and upper bearing  67 . 
     Movable portion core  61  is fixed to one of coil  48  and magnet  65 , is disposed to surround both of coil  48  and magnet  65 , and configures the outer periphery of movable body  60 . 
     In Embodiment, movable portion core  61  is a magnetic body having a covered tubular shape, and functions as a yoke. Movable portion core  61  is configured of, for example, the same type of magnetic material as center yoke  63 , and configures the magnetic circuit with coil  48 , magnet  65 , and center yoke  63 . In addition, movable portion core  61  has ring core  612  and flat plate core (corresponds to a top surface portion)  614 , and has a function of serving as a main body portion of movable body  60  as well as a function of serving as a weight, in movable body  60 . 
     Movable portion core  61  is configured by fixing ring core  612  to annular plate-shaped flat plate core  614  having an opening portion into which shaft  36  is inserted at the center such that the movable portion core protrudes downwards from an outer peripheral portion of the flat plate core. Although the movable portion core is formed in a covered tubular shape with ring core  612  and flat plate core  614 , without being limited thereto, the movable portion core may be configured to have an integral structure. However, in a case where movable portion core  61  has the integral structure, cutting is necessary, a large amount of materials are disposed, processing man-hours also increase, and costs increase. On the other hand, since movable portion core  61  of Embodiment is configured with assembling divided tubular ring core  612  and plate-shaped flat plate core  614  into one, it is possible to prepare the movable portion core through pressing, and cost reduction can be better achieved than the integral structure. 
     In movable portion core  61 , specifically, in ring core  612 , flat plate core  614 , magnet  65 , and center yoke  63  are disposed in turn such that respective opening portions in the middle are continuous on the same axis. Shaft  36  is inserted to the continuous opening portions to freely move. 
     Magnet  65  has the axial direction of coil  48  as the magnetization direction, and is disposed toward a magnetized surface. Magnet  65  is formed in a cylindrical shape, and is magnetized in two open directions, that is, the vibration direction (which is the axial direction of shaft  36  and corresponds to the axial direction of coil  48 ). In Embodiment, magnet  65  is disposed to be positioned on the radially inner side of coil  48  with the predetermined interval placed with respect to coil  48 . The predetermined radial interval is an interval allowing magnet  65  and coil  48  to be movable with respect to each other such that the magnet and the coil are taken out or put in the magnetization direction. In Embodiment, magnet  65  is disposed such that an upper end surface of coil  48  of lower fixing body  40  is positioned at a center position of the magnet in the magnetization direction, as illustrated in  FIG. 3 . Magnet  65  may have any shape other than a cylindrical shape insofar as the magnet is disposed on the inner side of coil  48  to face each magnetized surface in the axial direction of coil  48 . 
     Center yoke  63  is disposed to be in close contact with magnet  65 , and a magnetic flux of magnet  65  is concentrated and thereby efficiently passes without leaking out. In Embodiment, center yoke  63  is positioned on the inner side of coil  48  to oppose, in a direction orthogonal to the axial direction, a middle part of coil  48  in the axial direction (the vibration direction). 
     Lower bearing  64  and upper bearing  67  are fitted in opening portions in the middle of center yoke  63  and flat plate core  614  respectively. 
     Shaft  36  is inserted in each of lower bearing  64  and upper bearing  67  in the axial direction to freely move, and movable body  60  itself is made to smoothly and freely move in the vibration direction along shaft  36 . 
     Lower bearing  64  and upper bearing  67  are disposed in center yoke  63  and flat plate core  614  such that magnet  65  is sandwiched therebetween in the axial direction, that is, the vibration direction. 
     Lower bearing  64  and upper bearing  67  are respectively formed in a tubular shape, and outer peripheries of end portions on a magnet  65  side are provided to protrude in the radial direction in a flange shape and configure retaining portions  642  and  672  respectively. 
     When lower bearing  64  is inserted (herein, press-fitted) in the opening portion of center yoke  63 , retaining portion  642  engages with step portion  632  having a recessed shape, which is formed on a surface of the opening portion of center yoke  63  on the magnet  65  side. 
     Accordingly, lower bearing  64  is disposed in a state of being sandwiched between center yoke  63  and magnet  65 , and does not come off center yoke  63  in response to sliding along shaft  36 , an external shock, or driving of vibration actuator  10 . In addition, the lower bearing does not come off at the time of assembly and even when a designed dimension error occurs. 
     When upper bearing  67  is inserted (herein, press-fitted) in the opening portion of flat plate core  614 , retaining portion  672  engages with step portion  6142  having a recessed shape, which is formed in flat plate core  614 . 
     Accordingly, upper bearing  67  is disposed in a state of being sandwiched between flat plate core  614  and magnet  65 , and does not come off flat plate core  614  in response to sliding along shaft  36 , an external shock, or driving of vibration actuator  10 . In addition, the lower bearing does not come off at the time of assembly and even when a designed dimension error occurs. 
     As described above, lower bearing  64  and upper bearing  67  respectively have retaining portions  642  and  672  which are on the side of magnet  65  disposed to be sandwiched therebetween, that is, a center side of movable body  60 . Since retaining portions  642  and  672  of lower bearing  64  and upper bearing  67  engage with step portions  632  and  6142  of center yoke  63  and flat plate core  614  respectively, lower bearing  64  and upper bearing  67  in movable body  60  are disposed in a retained state. 
     Ring core  612  is a tubular body, and is bonded to elastic support portion  50  in Embodiment. Specifically, bonded end portion  6124  of ring core  612 , which is an end portion on a bottom surface side, that is, a reverse side with respect to flat plate core  614 , is bonded to elastic support portion  50 . In Embodiment, bonded end portion  6124  is a lower end portion of ring core  612  which is open, is annularly formed in a circumferential direction along an opening edge portion, and bonds and fixes elastic support portion  50 . Bonded end portion  6124  has tubular swaging claw portion  6124   a  protruding in an opening direction, herein downwards, and fixing stepped surface  6124   b  which is on a base end portion side of swaging claw portion  6124   a  and is orthogonal to swaging claw portion  6124   a.    
     In a part of an outer peripheral surface of ring core  612 , flat surface portion  6128  is provided at a symmetrical position with respect to the center of ring core  612 . Flat surface portion  6128  is a part that can reliably sandwich cylindrical ring core  612  therein by means of a fixing jig that fixes an object by sandwiching the object therein. Even when ring core  612  is cylindrical, ring core  612  can be reliably fixed by flat surface portion  6128  causing the fixing jig to easily sandwich the ring core therein when bonding bonded end portion  6124  to inner peripheral bonding portion  506  of elastic support portion  50 . For example, this process can be stably performed when fixing bonded end portion  6124  to inner peripheral bonding portion  506  of elastic support portion  50  through swaging (so-called, deforming). 
     Ring core  612  is disposed to be adjacent to an outer periphery of a vicinity of a bonding part with elastic support portion  50 , herein, bonded end portion  6124 , and has notched escape portion  6122  for avoiding interference of elastic support portion  50  at the time of deformation. 
     In ring core  612 , swaging claw portion  6124   a  and fixing stepped surface  6124   b  of bonded end portion  6124  are provided on a lower end side of escape portion  6122 . 
     Escape portion  6122  escapes and avoids interference of elastic support portion  50  when movable body  60  moves to a base plate  42  side. Since elastic support portion  50  is bonded to a lower end portion (bonded end portion  6124 ) of movable body  60 , movable body  60  moves in a direction of separating away from the deformed part of elastic support portion  50  even when movable body  60  moves to the flat plate core  614  side. Thus, the escape portion at that time is unnecessary. 
     A length of escape portion  6122  in the axial direction, that is, the vibration direction is set by elastic support portion  50  bonded to an opening end portion of escape portion  6122  on one end side (herein, the lower end side), specifically, a movable range of the spring. 
     A length of escape portion  6122  in the vibration direction (an opening range) is set to the movable range of the plate spring which is elastic support portion  50 , that is, a length of ½ to ⅔ of a movable range of movable body  60  (also referred to as an “escape dimension” which is a dimension for avoiding interference of elastic support portion  50  at the time of deformation). By setting the escape dimension to ½ to ⅔ of the movable range, the vibration actuator can be driven in a state where the mass of movable body  60  is maintained without the interference of the plate spring, which is elastic support portion  50 . 
       FIG. 12  is a perspective view illustrating a bonding portion between elastic support portion  50  and ring core  612  of movable body  60 .  FIGS. 13A and 13B  are views provided for illustrating the bonding portion between elastic support portion  50  and ring core  612  of movable body  60 .  FIG. 13A  illustrates a state where annular inner peripheral bonding portion  506  is fitted in bonded end portion  6124  of ring core  612 .  FIG. 13B  illustrates a state where annular inner peripheral bonding portion  506  is bonded to ring core  612 . First, elastic support portion  50  will be described with reference to  FIG. 12 . 
     Outer peripheral bonding portion  502  which is the other end portion on an outer peripheral side and inner peripheral bonding portion  506  which is one end portion on an inner peripheral side in elastic support portion  50  can be displaced in a thickness direction in response to elastic deformation. Elastic support portion  50  is disposed to be orthogonal to a movement direction of movable body  60  (herein, in a horizontal direction) at normal times. 
     Specifically, elastic support portion  50  is a ring-shaped plate spring having an opening in the middle, and has outer peripheral bonding portion  502  disposed on the outer peripheral side, inner peripheral bonding portion  506  disposed on the inner peripheral side, and arm portion  504  that connects outer peripheral bonding portion  502  to inner peripheral bonding portion  506 . 
     In Embodiment, outer peripheral bonding portion  502  and inner peripheral bonding portion  506  in elastic support portion  50  are respectively formed in an annular shape, and are disposed with an interval placed. Arcuate arm portion  504  disposed within the interval elastically deforms with both end portions of arm portion  504  being connected to outer peripheral bonding portion  502  and inner peripheral bonding portion  506  respectively. Mainly in response to the elastic deformation of arm portion  504 , outer peripheral bonding portion  502  and inner peripheral bonding portion  506  are freely displaced in the thickness direction. Displaced amounts of outer peripheral bonding portion  502  and inner peripheral bonding portion  506  can be adjusted in accordance with a length of arm portion  504 . 
     As illustrated in  FIG. 3 , elastic support portion  50  is bonded to movable body  60  with inner peripheral bonding portion  506  on the inner peripheral side, and is fixed to fixing body  20  with outer peripheral bonding portion  502  on the outer peripheral side. 
     Annular inner peripheral bonding portion  506  of elastic support portion  50  is bonded by being fitted onto bonded end portion  6124  (specifically, swaging claw portion  6124   a ) of ring core  612 , and is fixed to extend from ring core  612  to a radially outer side of ring core  612 . 
     Although welding, adhesion, or the like may be used in bonding elastic support portion  50  to ring core  612 , the other end portion of elastic support portion  50  is bonded by being fitted onto swaging claw portion  6124   a  of ring core  612  and thereby swaging swaging claw portion  6124   a  in Embodiment as illustrated in  FIGS. 13A and 13B . 
     Specifically, as illustrated in  FIG. 13A , inner peripheral bonding portion  506  of elastic support portion  50  is fitted onto lower end portion  6124  of ring core  612 , thereby being positioned on annular fixing stepped surface  6124   b.    
     Next, by striking or tightening swaging claw portion  6124   a , inner peripheral bonding portion  506  is sandwiched between fixing stepped surface  6124   b  and the swaging claw portion and is firmly fastened, as illustrated in  FIG. 13B . 
     Accordingly, inner peripheral bonding portion  506  is reliably fixed by swaging the entire periphery of ring core  612 . Consequently, in a case where adhesion is used, the inner peripheral bonding portion does not come off even when a force that causes the inner peripheral bonding portion to come off at the time of driving is applied. In addition, unlike a case where welding is used, it is not necessary to provide a space for welding in each component of movable body  60  or elastic support portion  50 . Accordingly, design freedom of the plate spring which is elastic support portion  50  does not reduce in order to secure this space. 
     In this manner, the plate spring which is elastic support portion  50  and movable body  60  can be firmly connected to each other, and design freedom of elastic support portion  50  can be increased. 
     The magnetic circuit illustrated in  FIG. 14  is formed in vibration actuator  10 . In addition, coil  48  is disposed, in vibration actuator  10 , to be orthogonal to a magnetic flux from magnet  65  and center yoke  63  of movable body  60 . Therefore, when electrical connection is performed as illustrated in  FIG. 14 , the Lorentz force in the −F-direction is generated in coil  48  in accordance with Fleming&#39;s left hand rule in response to interaction between a magnetic field of magnet  65  and a current flowing in coil  48 . 
     A direction of the Lorentz force in the −F-direction is a direction orthogonal to a direction of the magnetic field and a direction of the current flowing in coil  48  (the base plate  42  side in  FIG. 14 ). Since coil  48  is fixed on the base plate  42  side (coil holder  44 , which is a lower fixing portion), an opposite force to the Lorentz force in the −F-direction is generated as thrust in the F-direction in movable body  60  having magnet  65  according to the law of action-reaction, and a movable body side where there is magnet  65  moves to the F-direction, that is, the flat plate core  614  (upper fixing body  30 ) side. Movable body  60  is driven in accordance with a drive signal, and comes into contact with (specifically, collides with) shock absorbing member  38  when the movable body has moved in the −F-direction depending on drive conditions. 
     In addition, when an electrical connection direction of coil  48  is switched to a reverse direction and then electrical connection to coil  48  is performed, the Lorentz force in the F-direction, which is the reverse direction, is generated. In response to the generation of the Lorentz force in the F-direction, an opposite force to the Lorentz force in the F-direction is generated as thrust (thrust in the −F-direction) in movable body  60  according to the law of action-reaction, and movable body  60  moves in the −F-direction, that is, the base plate  42  (lower fixing body  40 ) side. Movable body  60  is driven in accordance with a drive signal, and comes into contact with (specifically, collides with) shock absorbing member  46  when the movable body has moved in the −F-direction depending on drive conditions. 
     Vibration actuator  10  has fixing body  20  having coil  48  and magnet  65  which is magnetized in the axial direction (AL) of coil  48  and is disposed on the radially inner side of coil  48 , and includes movable body  60  movably disposed on the inner side of coil  48  in the axial direction of coil  48  in a state of being elastically held by elastic support portion  50 . 
     In vibration actuator  10 , outer peripheral bonding portion  502  of elastic support portion  50  which is the plate spring having inner peripheral bonding portion  506  fixed to movable body  60  is fixed by being sandwiched between upper fixing body  30  and lower fixing body  40  which configure fixing body  20 . Accordingly, in a state of being separated away from a top surface (flat plate core  614 ) and a bottom surface (base plate  42 ) of vibration actuator  10 , elastic support portion  50  supports movable body  60  to freely move. 
     Accordingly, since movable unit  70  having movable body  60  is fixed inside the housing of fixing body  20  formed with case  32  and base plate  42  by being sandwiched between upper spring fixing portion  34  and coil holder  44 , desired vibration is obtained, ease of assembly is good, a structure is simple, and process cost reduction can be achieved. In addition, since shaft  36  is included, shock resistance is further enhanced, and vibration that is actually felt can be sufficiently obtained. 
     Herein, vibration actuator  10  is driven by an alternating current wave input from the power supply section (not illustrated) to coil  48 . That is, the electrical connection direction of coil  48  is periodically switched, and thrust in the F-direction of the flat plate core  614  side and thrust in the F-direction on the base plate  42  side alternately act on movable body  60 . Accordingly, movable body  60  vibrates in a winding axis direction of coil  48 , that is, an extension direction of shaft  36 . 
     Hereinafter, a driving principle of vibration actuator  10  will be briefly described. In vibration actuator  10  of Embodiment, in a case where the mass of movable body  60  is indicated with m (kg), and a spring constant of the spring (the plate spring) in a torsional direction is indicated with K sp , movable body  60  vibrates with respect to fixing body  20  at resonant frequency f r  (Hz) calculated by following equation 1. 
     
       
         
           
             
               
                 
                   
                     ( 
                     
                       Equation 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       1 
                     
                     ) 
                   
                   ⁢ 
                   
                       
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     f 
                     r 
                   
                   = 
                   
                     
                       1 
                       
                         2 
                         ⁢ 
                         π 
                       
                     
                     ⁢ 
                     
                       
                         
                           K 
                           sp 
                         
                         m 
                       
                     
                   
                 
               
               
                 
                   [ 
                   1 
                   ] 
                 
               
             
           
         
       
     
     When an alternating current wave having a frequency equal to resonant frequency f r  of movable body  60  is input into coil  48 , movable body  60  comes into a resonance state since movable body  60  is considered to configure a mass part in a vibration model of a spring-mass system. That is, by inputting the alternating current wave having the frequency which is substantially equal to resonant frequency f r  of movable body  60  from the power supply section into coil  48 , movable body  60  can be efficiently vibrated. 
     An equation of motion and a circuit equation expressing the driving principle of vibration actuator  10  are as follows. Vibration actuator  10  is driven based on the equation of motion expressed as following equation 2 and the circuit equation expressed as following equation 3. 
     
       
         
           
             
               
                 
                   
                     ( 
                     
                       Equation 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       2 
                     
                     ) 
                   
                   ⁢ 
                   
                       
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     m 
                     ⁢ 
                     
                       
                         
                           d 
                           2 
                         
                         ⁢ 
                         
                           x 
                           ⁡ 
                           
                             ( 
                             t 
                             ) 
                           
                         
                       
                       
                         dt 
                         2 
                       
                     
                   
                   = 
                   
                     
                       
                         K 
                         f 
                       
                       ⁢ 
                       
                         i 
                         ⁡ 
                         
                           ( 
                           t 
                           ) 
                         
                       
                     
                     - 
                     
                       
                         K 
                         sp 
                       
                       ⁢ 
                       
                         x 
                         ⁡ 
                         
                           ( 
                           t 
                           ) 
                         
                       
                     
                     - 
                     
                       D 
                       ⁢ 
                       
                         
                           dx 
                           ⁡ 
                           
                             ( 
                             t 
                             ) 
                           
                         
                         dt 
                       
                     
                   
                 
               
               
                 
                   [ 
                   2 
                   ] 
                 
               
             
           
         
       
     
     m: mass (kg) 
     x(t): displacement (m) 
     K f : thrust constant (N/A) 
     i(t): current (A) 
     K sp : spring constant (N/m) 
     D: damping coefficient (N/(m/s)) 
     
       
         
           
             
               
                 
                   
                     ( 
                     
                       Equation 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       3 
                     
                     ) 
                   
                   ⁢ 
                   
                       
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     e 
                     ⁡ 
                     
                       ( 
                       t 
                       ) 
                     
                   
                   = 
                   
                     
                       Ri 
                       ⁡ 
                       
                         ( 
                         t 
                         ) 
                       
                     
                     + 
                     
                       L 
                       ⁢ 
                       
                         
                           di 
                           ⁡ 
                           
                             ( 
                             t 
                             ) 
                           
                         
                         dt 
                       
                     
                     + 
                     
                       
                         K 
                         e 
                       
                       ⁢ 
                       
                         
                           dx 
                           ⁡ 
                           
                             ( 
                             t 
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                         dt 
                       
                     
                   
                 
               
               
                 
                   [ 
                   3 
                   ] 
                 
               
             
           
         
       
     
     e(t): voltage (V) 
     R: resistance (Ω) 
     L: inductance (H) 
     K e : back electromotive force constant (V/(rad/s)) 
     That is, mass m (kg), displacement x(t) (m), thrust constant K f  (N/A), current i(t) (A), spring constant K sp  (N/m), and damping coefficient D (N/(m/s)) in vibration actuator  10  can be modified as appropriate within a range that equation 2 is satisfied. In addition, voltage e(t) (V), resistance R (Ω), inductance L (H), and back electromotive force constant K e  (V/(rad/s)) can be modified as appropriate within a range that equation 3 is satisfied. 
     In this manner, in a case where electrical connection to coil  48  is performed by an alternating current wave corresponding to resonant frequency f r  determined by mass m of movable body  60  and spring constant K sp  of elastic support portion  50  which is the plate spring, a large vibration output can be efficiently obtained in vibration actuator  10 . 
     In addition, vibration actuator  10  satisfies equations 2 and 3, and is driven in response to resonance in which a resonant frequency expressed in equation 1 is used. Accordingly, power consumed in a stationary state is only a loss caused by load torque and a loss caused by friction in vibration actuator  10 , and thereby movable body  60  can be driven with low power consumption, that is, can be linearly oscillated with low power consumption. 
     According to Embodiment, vibration actuator  10  can be assembled by elastic support portion  50  of movable unit  70  being sandwiched between upper fixing body  30  having upper spring fixing portion  34  and lower fixing body  40  having coil holder  44 . That is, after assembling upper fixing body  30 , lower fixing body  40 , and movable unit  70  into one in advance at the time of assembly, vibration actuator  10  can be assembled by simply assembling the portions into one. 
     According to Embodiment, a plurality of deflection portions (protrusions)  344  are provided on the other end portion (the upper end portion) of upper spring fixing portion  34  that causes outer peripheral bonding portion  502  of elastic support portion  50  to be sandwiched between one end portion (a lower end portion) and coil holder  44 . Accordingly, at the time of assembly of vibration actuator  10 , it is possible to adjust a height dimension by deflection portions  344  deflecting. That is, deflection portions  344  deflect even in a case where a component (for example, coil holder  44 ) protrudes to the outer side due to a cumulative tolerance of each component when putting outer peripheral bonding portion  502  of elastic support portion  50  projecting from an outer peripheral part of movable unit  70  into case  32  by the outer peripheral bonding portion being sandwiched between upper spring fixing portion  34  and coil holder  44  at the time of assembly of vibration actuator  10 . Therefore, the components can be suitably accommodated and assembled into one, it is not necessary to forcibly perform assembly, and case  32  does not deform. 
     In addition, there is a possibility that the elastic support portion which deforms at the time of movement of the movable body interferes with the movable body in a configuration where the elastic support portion is disposed between the cylindrical movable body and the fixing body disposed to surround the outer periphery thereof and is attached to both of the cylindrical movable body and the fixing body, which is a configuration of the actuator. 
     On the other hand, in vibration actuator  10  of Embodiment, elastic support portion  50  is bonded to one end portion of movable body  60  in the vibration direction, herein, bonded end portion  6124  which is the lower end portion, and escape portion  6122  is provided to be adjacent to bonded end portion  6124 . Accordingly, even when movable body  60  moves and is displaced in the vibration direction, elastic support portion  50  which supports the movable body by deforming this displaced state does not interfere with movable body  60 . 
     In addition, this escape portion  6122  is formed to be depressed at a length of ½ to ⅔ of the movable range of movable body  60  in the vibration direction (the axial direction of coil  48 ). Accordingly, vibration output reduction can be prevented by securing suitable mass in the movable range of movable body  60  without making the mass of ring core  612  which is a part of movable portion core  61  small more than it needs to be in order to form escape portion  6122 . 
     In addition, vibration actuator  10  of Embodiment can be used in an electric beauty equipment such as a facial massage machine that requires vibration, in addition to the aforementioned mobile device. 
     The present invention can be changed in various ways without departing from the spirit of the present invention, and it is evident that the present invention includes the changes. For example, bonding of bonded end portion  6124  to elastic support portion  50  is not limited to swaging of swaging claw portion  6124   a , fixing by applying an adhesive to a contact area between bonded end portion  6124  and elastic support portion  50  or a vicinity thereof, fixing by welding, and fixing by causing elastic support portion  50  to be sandwiched between bonded end portion  6124  and another member may be adopted. 
     INDUSTRIAL APPLICABILITY 
     The vibration actuator according to the present invention is easily assembled with a simple configuration, functions as a vibration generation source which exhibits desired vibration output, and is useful as an actuator mounted onto a mobile device that gives vibration to a user. 
     REFERENCE SIGNS LIST 
     
         
           10  Vibration actuator 
           20  Fixing body 
           30  Upper fixing body (First fixing body) 
           32  Case 
           34  Upper spring fixing portion (Abutment portion) 
           36  Shaft 
           38  Shock absorbing member 
           40  Lower fixing body (Second fixing body) 
           42  Base plate 
           44  Coil holder (Lower spring fixing portion, second fixing body) 
           46  Shock absorbing member 
           48  Coil 
           50  Elastic support portion 
           60  Movable body 
           61  Movable portion core 
           63  Center yoke 
           64  Lower bearing 
           65  Magnet 
           67  Upper bearing 
           70  Movable unit 
           322  Upper surface portion 
           324  Peripheral wall portion 
           342  Upper abutment portion 
           344  Deflection portion (Protrusion) 
           422  Protruding plate portion 
           428  Positioning recessed portion 
           442  Folder main body 
           444  Lower abutment portion 
           446  Leading portion 
           448  Positioning protrusion portion 
           502  Outer peripheral bonding portion 
           504  Arm portion 
           506  Inner peripheral bonding portion 
           612  Ring core 
           614  Flat plate core 
           632  Step portion 
           642 ,  672  Retaining portion 
           3241  Claw portion 
           6122  Escape portion 
           6124  Bonded end portion (Lower end portion) 
           6124   a  Swaging claw portion 
           6124   b  Fixing stepped surface 
           6128  Flat surface portion 
           6142  Step portion