Abstract:
There is provided a linear vibrator including a housing providing an internal space; a magnetic field part having a yoke disposed in the internal space and a magnet magnetized on a surface of the yoke and vibrating in the internal space by an interaction with a coil to which power is applied; an elastic member connecting the yoke and the housing and allowing the magnetic field part to be elastically supported in the internal space; and a magnetic flux collecting part collecting magnetic flux of the magnetic field part and allowing the magnetic field part to move towards the coil.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 10-2010-0057089 filed on Jun. 16, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a linear vibrator and an electronic device having the same, and more particularly, to a linear vibrator preventing or rapidly removing minute vibrations that may be caused by external impacts and an electronic device having the same. 
         [0004]    2. Description of the Related Art 
         [0005]    A linear vibrator is a device transforming electrical energy into mechanical vibrations using a principle of generating electromagnetic force. The linear vibrator is mounted on an electronic device such as a mobile communication terminal, a game machine, or the like, for soundless call reception notification and vibration transfer. 
         [0006]    In recent years, a mobile communication terminal has been small and slim, and the linear vibrator mounted thereon has also been reduced in size and improved in functionality. 
         [0007]    A linear vibrator according to the related art has an internal space including a stator and a vibrator vibrating by electromagnetic interaction. 
         [0008]    Since internal components forming the vibrator and the stator are disposed in the internal space in such a manner as to realize a high-density configuration, there is interference between the internal components due to the vibrations of the vibrator. 
         [0009]    Also, when an impact is applied to the linear vibrator, the vibrator hung within the internal space makes repeated contact and non-contact with the other components to thereby cause minute vibrations. 
         [0010]    Therefore, research into a linear vibrator capable of removing minute vibrations, even if the high-density internal space thereof has been realized, is necessary. 
       SUMMARY OF THE INVENTION 
       [0011]    An aspect of the present invention provides a linear vibrator including a magnetic flux collecting part. The magnetic flux collecting part is fixed to a coil providing a vibrating space, in which a magnet vibrates while being supported by an elastic member, and collects the magnetic flux of magnetic fluid provided between the magnet and the coil. 
         [0012]    An aspect of the present invention also provides an electronic device having the linear vibrator mounted thereon. 
         [0013]    According to an aspect of the present invention, there is provided a linear vibrator including: a housing providing an internal space; a magnetic field part having a yoke disposed in the internal space and a magnet magnetized on a surface of the yoke and vibrating in the internal space by an interaction with a coil to which power is applied; an elastic member connecting the yoke and the housing and allowing the magnetic field part to be elastically supported in the internal space; and a magnetic flux collecting part collecting magnetic flux of the magnetic field part and allowing the magnetic field part to move towards the coil. 
         [0014]    The linear vibrator may further include a coil damping portion provided between the coil and the magnet and relieving an impact generated when the magnetic field part and the coil are in contact with each other due to magnetic action of the magnetic flux collecting part. 
         [0015]    The coil damping portion may include a magnetic fluid band formed along an outer surface of the magnet. 
         [0016]    The coil may be wound so as to form a space in which the magnetic field part vibrates and moves, and the magnetic flux collecting part may be provided on the coil. 
         [0017]    The magnetic flux collecting part may include a metallic piece and may be adhesively fixed to an upper portion or inner circumferential surface of the coil. 
         [0018]    The coil may be shaped as a cylinder so as to form a space in which the magnetic field part vibrates and moves, and the magnetic flux collecting part may include a plurality of metallic pieces formed on a ring-shaped rim portion fixed to the coil. 
         [0019]    The magnetic flux collecting part may include magnetic powder and may be adhesively fixed to an upper portion or inner circumferential surface of the coil. 
         [0020]    The magnetic flux collecting part may include magnetic liquid and may be adhesively fixed to an upper portion or inner circumferential surface of the coil. 
         [0021]    The coil may be shaped as a cylinder so as to form a space in which the magnetic field part vibrates and moves, and the magnetic flux collecting part may be forcibly fitted around the coil. 
         [0022]    The yoke may include a magnet fixing portion having the magnet fixed thereto; a mass body fixing portion bent from the magnet fixing portion in a direction in which the magnet is magnetized and having a mass body fixed thereto; and a claw portion bent from the mass body fixing portion and supporting a lower portion of the mass body. 
         [0023]    The housing may include an upper case shaped as a cylinder having an open lower portion; and a bracket sealing the lower portion of the upper case and having the coil magnetized thereon. 
         [0024]    The magnetic field part may further include a yoke plate fixed to a surface of the magnet opposite to a surface thereof in contact with the yoke and preventing magnetic leakage. 
         [0025]    The housing may include a bracket damper on a surface thereof, the bracket damper preventing the magnetic field part from making contact with the housing due to vibrations of the magnetic field part. 
         [0026]    According to another aspect of the present invention, there is provided a linear vibrator including: an upper case shaped as a cylinder having an open lower portion; a bracket fixed to the open lower portion of the upper case to form an internal space and having a coil fixed thereto, the coil receiving power applied thereto from an external source; a magnetic field part including a yoke disposed in the internal space, a magnet magnetized on a surface of the yoke, and a yoke plate provided on a surface of the magnet opposite to a surface thereof in contact with the yoke, and vibrating in a space within the coil; an elastic member connecting the upper case and the yoke and allowing the magnetic field part to be elastically supported in the internal space; and a magnetic flux collecting part collecting magnetic flux of the magnetic field part while breaking a balance of the magnetic flux from the magnetic field part to the coil, and provided on part of an upper portion or inner surface of the coil. 
         [0027]    The linear vibrator may further include a magnetic fluid band provided along an outer surface of the magnet and relieving an impact generated when the magnetic field part and the coil are in contact with each other due to magnetic action of the magnetic flux collecting part. 
         [0028]    The magnetic flux collecting part may include a metallic piece adhesively fixed to the coil. 
         [0029]    The magnetic flux collecting part may include a plurality of metallic pieces formed on a ring-shaped rim portion fixed to the coil, and the metallic pieces may cause eccentricity in the magnetic flux. 
         [0030]    The magnetic flux collecting part may include magnetic powder adhesively fixed to the coil. 
         [0031]    The magnetic flux collecting part may include magnetic liquid fixedly applied to the coil. 
         [0032]    The magnetic flux collecting part may include a metallic piece forcibly fitted around the coil. 
         [0033]    The yoke may include a magnet fixing portion having the magnet fixed thereto; a mass body fixing portion bent from the magnet fixing portion in a direction in which the magnet is magnetized and having a mass body fixed thereto; and a claw portion bent from the mass body fixing portion and supporting a lower portion of the mass body. 
         [0034]    The linear vibrator may further include a bracket damper provided on the bracket so as to prevent the magnetic field part from making contact with the bracket due to vibrations of the magnetic field part. 
         [0035]    According to another aspect of the present invention, there is provided an electronic device including: the linear vibrator; a circuit board having the linear vibrator mounted thereon; and a case having the circuit board in an internal space thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0037]      FIG. 1  is a partially cut-away perspective view schematically illustrating a linear vibrator according to an exemplary embodiment of the present invention; 
           [0038]      FIG. 2  is a schematic cross-sectional view illustrating the linear vibrator of  FIG. 1 ; 
           [0039]      FIG. 3  is an enlarged cross-sectional view of portion A of  FIG. 2 ; 
           [0040]      FIG. 4  is a plan view illustrating the linear vibrator of  FIG. 1  with the exception of an upper case and a magnetic field part; 
           [0041]      FIG. 5  is a schematic perspective view illustrating an elastic member according to an exemplary embodiment of the present invention; 
           [0042]      FIG. 6  is a plan view of the linear vibrator of  FIG. 1  to which a first modified example of a magnetic flux collecting part provided on a coil is applied; 
           [0043]      FIG. 7  is an enlarged cross-sectional view of portion A of  FIG. 2  illustrating a second modified example of the magnetic flux collecting part provided on the coil; 
           [0044]      FIG. 8  is an enlarged cross-sectional view of portion A of  FIG. 2  illustrating a third modified example of the magnetic flux collecting part provided on the coil; 
           [0045]      FIG. 9  is a schematic cross-sectional view illustrating a phenomenon in which magnetic flux generated in a magnetic field part is collected in a magnetic flux collecting part; and 
           [0046]      FIG. 10  is an exploded perspective view schematically illustrating an electronic device including a linear vibrator according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0047]    Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0048]    Throughout the drawings, the same reference numerals will be used to designate the same or like elements. 
         [0049]    Linear Vibrator 
         [0050]      FIG. 1  is a partially cut-away perspective view schematically illustrating a linear vibrator according to an exemplary embodiment of the present invention.  FIG. 2  is a schematic cross-sectional view illustrating the linear vibrator of  FIG. 1 .  FIG. 3  is an enlarged cross-sectional view of portion A of  FIG. 2 .  FIG. 4  is a plan view illustrating the linear vibrator of  FIG. 1  with the exception of an upper case and a magnetic field part.  FIG. 5  is a schematic perspective view illustrating an elastic member according to an exemplary embodiment of the present invention. 
         [0051]    With reference to  FIGS. 1 through 5 , a linear vibrator  1  according to an exemplary embodiment of the invention may include a housing  10 , a magnetic field part  20 , an elastic member  40  and a magnetic flux collecting part  60 . 
         [0052]    The housing  10  may have an internal space in which internal components are disposed. The housing  10  may be configured in various manners. Particularly, the housing  10  should allow the internal components to be easily arranged and assembled therein. 
         [0053]    The housing  10  in the present embodiment may include an upper case  12  having the form of a cylinder of which a lower portion is open, and a bracket  14  sealing the lower portion of the upper case  12  and having a coil  50  magnetized thereon. 
         [0054]    A printed circuit board  52  may be mounted on the bracket  14 . The printed circuit board  52  may be manufactured as a flexible printed circuit board (FPCB). 
         [0055]    The printed circuit board  52  may include a connection terminal portion  56  allowing the linear vibrator  1  to be connected to a circuit board  110  of an electronic device  100  of  FIG. 10 . 
         [0056]    The magnetic field part  20  may generate a magnetic field of a certain strength and have a yoke  22  and a magnet  24  disposed in the internal space of the housing  10 . The magnet  24  is coupled with a yoke plate  26  on a surface of the magnet  24  opposite to a surface thereof in contact with the yoke  22  to prevent magnetic leakage. 
         [0057]    The yoke  22  may have the form of a cylinder of which a top portion is sealed and a lower portion is open. Specifically, the yoke  22  may include a magnet fixing portion  222  having the magnet  24  fixed thereto, a mass body fixing portion  224  bent from the magnet fixing portion  222  in a direction in which the magnet  24  is magnetized and having a mass body  30  fixed thereto, and a claw portion  226  bent from the mass body fixing portion  224  and supporting a lower portion of the mass body  30 . 
         [0058]    The yoke  22  and the magnet  24  may be fixed in a manner such that the magnet  24  is bonded onto a surface of the yoke  22  by an adhesive. 
         [0059]    An inner circumferential surface of the yoke  22  has a diameter larger than an outer circumferential surface of the magnet  24 . An air gap AG of a certain size may be formed between the inner circumferential surface of the yoke  22  and the outer circumferential surface of the magnet  24 . 
         [0060]    The coil  50  may be disposed in the air gap AG and may allow current to flow in the magnetic field generated by the magnetic field part  20  to thereby cause the magnetic field part  20  to vibrate. 
         [0061]    The coil  50  may have the form of a cylinder in which a space for the movement of the magnetic field part  20  is formed. That is, the coil  50  may be wound while allowing for the formation of the space in which the magnetic field part  20  vibrates and moves. Further, a coil damping portion  80  may be provided in a gap between the magnetic field part  20  and the coil  50  so as to relieve an impact when the magnetic field part  20  and the coil  50  are in contact with each other. 
         [0062]    The coil damping portion  80  may be a magnetic fluid band  82  formed along an outer surface of the magnet  24 . 
         [0063]    A bracket damper  55  may be formed on the upper surface of the bracket  14  to prevent the magnetic field part  20  from making contact with the housing  10  due to the vibrations of the magnetic field part  20 . The bracket damper  55  may be modified to have various shapes, and the bracket damper  55  may be formed of rubber. 
         [0064]    The elastic member  40  may be a spring member such as a plate spring or a coil spring. The elastic member  40  may include a housing fixing portion  42  fixed to a surface of the upper case  12 , a yoke fixing portion  46  being in contact with a surface of the yoke  22  opposite to the surface thereof in contact with the magnet  24 , and a plurality of connection strip portions  44  disposed to form an elastic space  45  between the housing fixing portion  42  and the yoke fixing portion  46 . 
         [0065]    The housing fixing portion  42  is a stationery portion of the elastic member  40 , which is fixed to the non-vibrating housing  10 . The yoke fixing part  46  is a free portion of the elastic member  40 , which vibrates due to the vibrations of the magnetic field part  20 . 
         [0066]    In order to relieve an impact generated when the magnetic field part  20  installed in the free portion of the elastic member  40  makes contact with the upper surface of the elastic member  40  due to the vibrations of the magnetic field part  20 , an upper case damper  43  may be installed in at least one of upper and lower portions of the elastic member  40 . 
         [0067]    The upper case damper  43  may include magnetic fluid and be fixed to the upper surface of the elastic member  40  by leakage flux of the magnet  24 . 
         [0068]    The yoke fixing portion  46  may be a flat circular plate, and the housing fixing portion  42  may be a ring-shaped rim portion having an opening in the center thereof. The connection strip portion  44  may have a spiral shape allowing for the connection between the yoke fixing portion  46  and the housing fixing portion  42 . 
         [0069]    The magnetic flux collecting part  60  collects the magnetic flux of the magnetic field part  20  and allows the magnetic field part  20  to move towards the coil  50 . That is, the magnetic flux collecting part  60  disturbs the balance of the magnetic flux between the magnetic field part  20  and the coil  50 . In order to break the balance of the magnetic flux from the magnetic field part  20  to the coil  50 , the magnetic flux collecting part  60  may collect part of the magnetic flux of the magnetic field part  20 . 
         [0070]      FIG. 9  is a schematic cross-sectional view illustrating a phenomenon in which the magnetic flux generated in the magnetic field part is collected in the magnetic flux collecting part. With reference to  FIG. 9 , it is better understood that the magnetic flux of the magnetic field part  20  is collected in the magnetic flux collecting part  60  provided on the coil  50 . 
         [0071]    The magnetic flux collecting part  60  may be installed in anyplace affecting the magnetic flux of the magnetic field part  20 . The magnetic flux collecting part  60  may be installed in the internal space by the use of a separate member, or may be installed on a structure present in the outside of the magnetic field part  20 . 
         [0072]    Here, the magnetic flux collecting part  60  may be provided on part of the upper portion or inner surface of the coil  50  present in the outside of the magnetic field part  20 . 
         [0073]    The magnetic flux collecting part  60  of  FIGS. 1 through 4  according to the present embodiment may be a metallic piece  62  formed on the upper portion of the coil  50 . The metallic piece  62  may be fixed to the coil  50  by an adhesive in order to prevent separation therebetween. 
         [0074]    Also, a flexible metallic thin film may be used in a manner such that it is adhesively fixed to the inner circumferential surface of the coil  50 . 
         [0075]    Modified Examples of Magnetic Flux Collecting Part 
         [0076]      FIG. 6  is a plan view of the linear vibrator of  FIG. 1  to which a first modified example of a magnetic flux collecting part provided on a coil is applied.  FIG. 7  is an enlarged cross-sectional view of portion A of  FIG. 2  illustrating a second modified example of a magnetic flux collecting part provided on a coil.  FIG. 8  is an enlarged cross-sectional view of portion A of  FIG. 2  illustrating a third modified example of a magnetic flux collecting part provided on a coil. 
         [0077]    The magnetic flux collecting part  60  of  FIG. 6  may be a plurality of metallic pieces  62  formed on the ring-shaped rim portion  64  fixed to the coil  50 . The rim portion  64  may be fixed to the coil  50  by an adhesive or another coupling portion. 
         [0078]    Here, the metallic pieces  62  may be disposed on the rim portion  64  having uniform or non-uniform intervals therebetween. The metallic pieces  62  may cause eccentricity in the magnetic flux from the magnetic field part  20  to the coil  50 . 
         [0079]    The magnetic flux collecting part  60  of  FIG. 7  may be a metallic piece  65  in which both side portions thereof are forcibly fitted around the coil  50 . 
         [0080]    In addition, the metallic piece  62  may also be fixed to the coil  50  by an adhesive for tight bonding. 
         [0081]    The magnetic flux collecting part  60  of  FIG. 8  may include magnetic liquid  66  fixedly applied to the coil  50 . The magnetic liquid  66  may be a mixture of magnetic powder and an adhesive serving as a binder, but is not limited thereto. 
         [0082]    Also, the magnetic flux collecting part  60  may be fixed to the coil  50  through only the use of magnetic powder. 
         [0083]    Electronic Device 
         [0084]      FIG. 10  is an exploded perspective view schematically illustrating an electronic device including a linear vibrator according to an exemplary embodiment of the present invention. 
         [0085]    The internal configuration of the linear vibrator  1  according to the embodiment of the invention may be applicable to various electronic devices requiring vibrations as well as a structure requiring vibrations such as a speaker. 
         [0086]    With reference to  FIG. 10 , the electronic device  100  according to an exemplary embodiment of the invention may include the linear vibrator  1 , a case  120 , and the circuit board  110 . 
         [0087]    The linear vibrator  1  may be mounted on the circuit board  110  disposed in the internal space of the case  120  through the use of various methods. The connection terminal portion  56  of the linear vibrator  1  and a connection terminal portion  112  of the circuit board  110  are connected to exchange signals. 
         [0088]    As set forth above, in a linear vibrator according to exemplary embodiments of the invention, when vibrations are generated in a vibrator (a magnetic field part) hung within an internal space due to external impacts, the vibrating magnetic field part makes contact with a coil, and thus minute vibrations generated in the magnetic field part can be rapidly removed. 
         [0089]    Also, since the minute vibrations caused by the external impacts are rapidly removed, this contributes to a reduction of noise and a reduction of interference between components, thereby achieving reliability in terms of durability. 
         [0090]    Furthermore, when magnetic fluid is injected between the magnetic field part and the interfering component in order to relieve an impact therebetween, minute vibrations can be reduced by a magnetic flux collecting part, whereby damping performance can be improved even when a small amount of magnetic fluid is injected. 
         [0091]    In addition, since the amount of the magnetic fluid is reduced, improved characteristics of the vibrator in relation to an amount of vibrations can be obtained. 
         [0092]    While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.