Patent Abstract:
There is provided a linear vibrator including: a housing having an internal space formed therein; a magnetic field unit including a yoke disposed in the internal space and having a magnet and a magnet insertion part formed therein, and interacting with a coil to which power is applied to linearly move in the internal space, the magnet insertion part determining an insertion position of the magnet; and an elastic member disposed in a space between the housing and the magnetic field unit and elastically supporting linear movement of the magnetic field unit.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of Korean Patent Application No. 10-2010-0045655 filed on May 14, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a linear vibrator, and more particularly, to a linear vibrator having increased internal component density and vibration force. 
     2. Description of the Related Art 
     A linear vibrator, a component converting electrical energy into mechanical vibrations using the principle of generating electromagnetic force, is mounted in an electronic apparatus such as a mobile communications terminal, a portable game machine, or the like, to be used for silently notifying a user of call reception by transferring vibrations thereto. 
     In accordance with the recent trend for compactness and slimness in mobile communications terminals, a compact, multi-functional linear vibrator has also been mounted therein. 
     A stator and a vibrator vibrated due to electromagnetic interaction therebetween are disposed in an internal space of the linear vibrator, according to the related art. 
     Components forming the vibrator and the stator, that is, an elastic member and a yoke, are surface-contacted with each other, thereby having difficulty in securing concentricity. 
     In addition, it has been difficult to increase the density of the linear vibrator due to the thickness of individual internal components. 
     As a result, there has been a limitation in increasing a size of a mass body within the internal space and it has been difficult to increase vibration strength. 
     Accordingly, there is a demand for research into a linear vibrator having a mass body increased in size. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention provides a linear vibrator having increased internal component density and vibration force. 
     According to an aspect of the present invention, there is provided a linear vibrator including: a housing having an internal space formed therein; a magnetic field unit including a yoke disposed in the internal space and having a magnet and a magnet insertion part formed therein, and interacting with a coil to which power is applied to linearly move in the internal space, the magnet insertion part determining an insertion position of the magnet; and an elastic member disposed in a space between the housing and the magnetic field unit and elastically supporting linear movement of the magnetic field unit. 
     The yoke may include a flat part having the magnet insertion part formed therein, a mass body fixing part being bent from the flat part in a mounting direction of the magnet to fix a mass body, and a claw part being bent from the mass body fixing part to support a bottom of the mass body. 
     One of the flat part and the elastic member may be provided with a protrusion part and the other may be provided with a protrusion part receiving hole, and the protrusion part may be fixedly coupled to the protrusion part receiving hole. 
     The magnet insertion part may include a dented part dented from the yoke to protrude from the yoke. 
     The dented part may be formed such that an outer surface thereof may be press-fitted into a dented part insertion part formed in the elastic member. 
     One of the elastic member and the flat part around the dented part may be provided with a protrusion part and the other may be provided with a protrusion part receiving hole, and the protrusion part may be fixedly coupled to the protrusion part receiving hole. 
     The housing may include a cylindrical upper case of which a lower portion is open and a bracket closing the lower portion of the upper case and having the coil mounted thereon. 
     A yoke plate may be provided on a surface opposite to a contact surface between the magnet and the yoke. 
     The coil may have a cylindrical shape such that a space in which the magnetic field unit moves is formed, and the magnetic fluid preventing a contact between the magnetic field unit and the coil may be provided in a clearance therebetween. 
     The housing may include a damper formed on a surface thereof, the damper preventing the magnetic field unit from contacting the housing due to vibrations. 
     According to another aspect of the present invention, there is provided a linear vibrator, including: a cylindrical upper case of which a lower portion is open; a bracket fixed to the open lower portion of the upper case to thereby form an internal space and having a coil fixed thereto, the coil having external power applied thereto; a magnetic field unit including a yoke disposed in the internal space and having a magnet and a magnet insertion part formed therein, and interacting with the coil to linearly move in the internal space when the power is applied to the coil, the magnet insertion part determining an insertion position of the magnet; and an elastic member configured of a ring-shaped housing fixing part fixed to the upper case, a yoke fixing part fixed to the other surface of the yoke, and a plurality of spiral connecting strip parts disposed such that an elastic space is formed between the housing fixing part and the yoke fixing part. 
     The yoke may include a flat part having the magnet insertion part formed therein, a mass body fixing part being bent from the flat part in a mounting direction of the magnet to fix a mass body, and a claw part being bent from the mass body fixing part to support a bottom of the mass body. 
     The yoke fixing part may have a flat plate shape, one of the flat part and the yoke fixing part may be provided with a protrusion part and the other may be provided with a protrusion part receiving hole, and the protrusion part may be fixedly coupled to the protrusion part receiving hole. 
     The yoke fixing part may have a through hole formed therein, the magnet insertion part may include a dented part dented from the yoke to protrude from the yoke, and the dented part may be press-fitted into the through hole to be fixed thereto. 
     One of an outer surface of the dented part and the yoke fixing part may be provided with a protrusion part and the other may be provided with a protrusion part receiving hole, and the protrusion part may be fixedly coupled to the protrusion part receiving hole. 
     The yoke fixing part may be fixedly bonded to the flat part, and an area of a bonding surface between the yoke fixing part and the flat part may be smaller than that of the yoke fixing part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a partially cut-away perspective view schematically showing a linear vibrator according to an exemplary embodiment of the present invention; 
         FIG. 2  is a cross-sectional view schematically showing the linear vibrator of  FIG. 1 ; 
         FIG. 3  is a perspective view schematically showing an elastic member according to an exemplary embodiment of the present invention; 
         FIG. 4  is an enlarged cross-sectional view showing a first modified example of part A of  FIG. 2 ; 
         FIG. 5  is a perspective view schematically showing an elastic member applied to  FIG. 4 ; 
         FIG. 6  is an enlarged cross-sectional view showing a second modified example of part A of  FIG. 2 ; 
         FIG. 7  is a perspective view schematically showing an elastic member applied to  FIG. 6 ; 
         FIG. 8  is a cross-sectional view showing a third modified example of  FIG. 2 ; 
         FIG. 9  is a cross-sectional view showing a fourth modified example of  FIG. 2 ; and 
         FIG. 10  is a perspective view schematically showing an elastic member applied to  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, it should be noted that the spirit of the present invention is not limited to the embodiments set forth herein and those skilled in the art and understanding the present invention could easily accomplish retrogressive inventions or other embodiments included in the spirit of the present invention by the addition, modification, and removal of components within the same spirit, but those are to be construed as being included in the spirit of the present invention. 
     Further, throughout the drawings, the same or similar reference numerals will be used to designate the same or like components having the same functions in the scope of the similar idea. 
       FIG. 1  is a partially cut-away perspective view schematically showing a linear vibrator according to an exemplary embodiment of the present invention;  FIG. 2  is a cross-sectional view schematically showing the linear vibrator of  FIG. 1 ; and  FIG. 3  is a perspective view schematically showing an elastic member according to an exemplary embodiment of the present invention. 
     In addition,  FIG. 4  is an enlarged cross-sectional view showing a first modified example of part A of  FIG. 2 , and  FIG. 5  is a perspective view schematically showing an elastic member applied to  FIG. 4 . 
     Referring to  FIGS. 1 through 5 , a linear vibrator  1  according to an exemplary embodiment of the present invention may include a housing  10 , a magnetic field unit  20 , and an elastic member  40 . 
     The housing  10  may have an internal space formed therein, wherein the internal space has internal components forming the vibrator disposed therein. The housing  10  may be implemented by various methods, and particularly, should be provided such that the internal components may be easily disposed therein. 
     The housing  10  according to an exemplary embodiment of the present invention may include a cylindrical upper case  12  of which a lower portion is open and a bracket  14  closing the lower portion of the upper case  12  and having a coil mounted thereon. 
     The magnetic field unit  20  may generate a magnetic field having a predetermined strength, and may include a yoke  22  and a magnet  24  that are disposed in the internal space of the housing  10 . In addition, the magnet  24  may include a yoke plate  26  formed on a surface opposite to a contact surface between the magnet  24  and the yoke  22 . 
     The yoke  22  may have a magnet insertion part  25  determining an insertion position of the magnet  24  in order to secure concentricity between the yoke  22  and the magnet  24 . 
     The yoke  22  has a cylindrical shape in which an upper portion thereof is closed and a lower portion thereof is opened, and more specifically, may include a flat part  222  having the magnet insertion part  25  formed therein, a mass body fixing part  224  formed to be bent from the flat part  222  in a mounting direction of the magnet  24  to fix a mass body  30 , and a claw part  226  formed to be bent from the mass body fixing part  224  to support a bottom of the mass body  30 . 
     The magnet  24  may be bonded and fixed to one surface of the yoke  22  using an adhesive. 
     A diameter of an inner circumferential surface of the yoke  22  is larger than that of an outer circumferential surface of the magnet  24 , such that an air gap (AG) having a predetermined size may be formed between the inner circumferential surface of the yoke  22  and the outer circumferential surface of the magnet  24 . 
     The coil  50 , allowing current to flow in a magnetic field formed by the magnetic field unit  20  and vibrate the magnetic field unit  20 , may be disposed within the air gap (AG). 
     The coil  50  may have a cylindrical shape so that a space in which the magnetic field unit  20  can move is formed, and the magnetic fluid  54  preventing the contact between the magnetic field unit  20  and the coil  50  may be provided in a clearance therebetween. 
     A damper  55  may be formed in an upper surface of the bracket  14  and prevent the magnetic field unit  20  from contacting the housing  10  due to vibration. The damper  55  may be made of a rubber material, or the like; however, a material of the damper may be variously selected. 
     The elastic member  40  may include a housing fixing part  42  fixed to any portion of the upper case  12 , a yoke fixing part  46  surface-contacting a surface opposite to the contact surface between the magnet  24  and the yoke  22 , and a plurality of connecting strip parts  44  disposed such that an elastic space  45  is formed between the housing fixing part  42  and the yoke fixing part  46 . 
     The housing fixing part  42  is a fixed end of the elastic member  40  fixed to the housing  10  that is not vibrated, and the yoke fixing part  46  is a free end of the elastic member  40  vibrated due to the vibration of the magnetic field unit  20 . 
     The elastic member  40  may be a spring member, the yoke fixing part  46  may have a flat plate shape, the housing fixing part  42  may have an annular rim shape of which the center is open, and the connecting strip parts  44  may have a spiral shape connecting the yoke fixing part  46  and the housing fixing part  42 . 
     Herein, the yoke fixing part  46  may be bonded and fixed to the flat part  222 . An area of a bonding surface formed by the bonding of the yoke fixing part  46  and the flat part  222  may be smaller than that of the yoke fixing part  46 . 
     When the area of the yoke fixing part  46  is larger than that of the bonding surface, assembly tolerance for the bonding may be secured to improve assembling efficiency. 
     The yoke  22  may have the magnet insertion part  25  determining the insertion position of the magnet  24  in order to secure concentricity between the yoke  22  and the magnet  24 , and may have a protrusion structure introduced in order to secure concentricity between the yoke  22  and the elastic member  40 . 
     One of the flat part  222  of the yoke  22  and the elastic member  44  is provided with a protrusion part  60 , and the other is provided with a protrusion part receiving hole  62 , wherein the protrusion part  60  may be fixedly coupled to the protrusion part receiving hole  62 . 
     Meanwhile, the magnet insertion part  25  may include a dented part  250  dented from the yoke  22  to protrude from the yoke  22 . 
     The exemplary embodiment of  FIGS. 2 and 3  shows a case in which the dented part  250  surface-contacts the yoke fixing part  46  to be fixed thereto, and the exemplary embodiment of  FIGS. 4 and 5  show a case in which the protrusion part  60  is formed in the dented part  250 , the protrusion part receiving hole  62  is formed in the elastic member  40 , and the protrusion part  60  is coupled to the protrusion part receiving hole  62  to match the concentricity between the yoke  20  and the elastic member  40 . 
       FIG. 6  is an enlarged cross-sectional view showing a second modified example of part A of  FIG. 2 , and  FIG. 7  is a perspective view schematically showing an elastic member applied to  FIG. 6 . 
     Referring to  FIGS. 6 and 7 , the dented part  250  may be dented from the flat part  222  of the yoke  22  to protrude to an upper portion of the flat part  222 . 
     The magnet insertion part  25  may include the dented part  250  dented from the yoke  22  to protrude from the yoke  22 . 
     The dented part  250  may be formed such that an outer surface thereof is press-fitted into a dented part insertion part  47  formed in the elastic member  40 . Accordingly, the concentricity between the elastic member  40  and the yoke  22  may be not only secured, but also the vibratory displacement of the magnetic field part  20  may be further secured, as compared to a case in which the dented part  250  surface-contacts the yoke fixing part  46  to be fixed thereto. 
     Herein, the magnetic fluid may applied to an upper surface of the elastic member  40  to dampen contact impacts between the elastic member  40  and the upper case  12 . 
       FIG. 8  is a cross-sectional view showing a third modified example of  FIG. 2 ;  FIG. 9  is a cross-sectional view showing a fourth modified example of  FIG. 2 ; and  FIG. 10  is a perspective view schematically showing an elastic member applied to  FIG. 9 . 
     Referring to  FIGS. 8 through 10 , one of the elastic member  40  and the flat part  222  around the dented part  250  is provided with the protrusion part  60 , and the other is provided with the protrusion part receiving hole  62 , wherein the protrusion part  60  may be fixedly coupled to the protrusion part receiving hole  62 . 
     The exemplary embodiment of  FIG. 8  shows a case in which the protrusion part  60  is formed in the elastic member  40 , and the exemplary embodiment of  FIG. 9  shows a case in which the protrusion part  60  is formed in the flat part  222 . 
     In the case of  FIG. 9 , the protrusion part receiving hole  62  may be formed in the yoke fixing part  46 . 
     As set forth above, according to the exemplary embodiment of the present invention, concentricity between a yoke and an elastic member and between the yoke and a magnet may be secured to avoid interference between the magnet or the yoke and the inner diameter or the outer diameter of a coil during the generation of external impacts, whereby the disconnection of the coil may be prevented. 
     Further, the yoke and the elastic member may be integrally formed to increase the internal space of a linear vibrator housing, whereby the size and the inner displacement of a mass body may be secured. 
     Further, the size and the inner displacement of the mass body may be secured, whereby the vibration force of the linear vibrator may be increased. 
     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.

Technology Classification (CPC): 1