Abstract:
A linear vibration motor according to an aspect of the invention may include: a case having a cavity to receive a mass therein; a movable part generating a magnetic field inside the case and moving in a transverse direction while being secured to the mass; a coil part generating a force, by which the mass performs a linear reciprocating motion, by interaction with the magnetic field generated from the movable part upon receiving power; and a support plate dividing the cavity in which the coil part is mounted to face the movable part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 10-2009-0022049 filed on Mar. 16, 2009, 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 vibration motor, and more particularly, to a linear vibration motor that vibrates in the transverse direction within a mobile terminal to thereby reduce the thickness of the mobile terminal. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, vibration motors convert electrical energy into mechanical vibrations by generating an electromagnetic force. Vibration motors have gradually been reduced in size and weight. These smaller vibration motors are mounted in mobile terminals and provide silent incoming call alerts and various vibration functions. 
         [0006]    Touch screen LCDs have been employed for the purposes of size reduction and high quality of mobile terminals. Increasing emphasis has been placed on improving vibration motors. For example, when a user touches a touch screen, a mobile phone will vibrate. 
         [0007]    In recent years, linear vibration motors have been used to allow touch screen phones to vibrate. Linear vibration motors are not based on the rotation principle of motors. However, linear vibration motors are driven by an electromagnetic force with resonance frequency determined using a spring provided within the vibration motor and a mass hanging from the spring to thereby generate vibrations. 
         [0008]    Here, the electromagnetic force is generated through interaction between a magnet located on the moving mass, and a coil part located at a position corresponding to the magnet and supplying a current having a predetermined frequency. 
         [0009]    The linear vibration motor is designed to generate vibrations in a direction perpendicular to the LCD screen. However, in case the linear vibration motor vibrates in the vertical direction, the linear vibration motor can generate vibrations when the mass moves while ensuring vertical displacement. This limits the thickness of the mobile terminal. 
         [0010]    That is, when the terminal has the reduced thickness, the amount of vibration being generated from the linear vibration motor may not increase. 
       SUMMARY OF THE INVENTION 
       [0011]    An aspect of the present invention provides a linear vibration motor that has a coil part provided on a support plate dividing a cavity of a case so that a mass within the cavity moves in the transverse direction to generate vibrations, and a movable part facing the coil part and secured to the mass and causing the mass to move in the transverse direction in conjunction with the coil part. 
         [0012]    According to an aspect of the present invention, there is provided a linear vibration motor including: a case having a cavity to receive a mass therein; a movable part generating a magnetic field inside the case and moving in a transverse direction while being secured to the mass; a coil part generating a force, by which the mass performs a linear reciprocating motion, by interaction with the magnetic field generated from the movable part upon receiving power; and a support plate dividing the cavity in which the coil part is mounted to face the movable part. 
         [0013]    The linear vibration motor may further include an elastic member interposed between the case and the mass and controlling the horizontal displacement of the mass moving in the transverse direction. 
         [0014]    The elastic member may be a coil spring, a torsion spring or a plate spring. 
         [0015]    The mass may be separated into two parts on the basis of the support plate, the movable part and a connection member may be connected and fixed at the top and bottom of the mass, respectively, and the support plate may be arranged between the movable part and the connection member. 
         [0016]    The mass may be separated into two parts on the basis of the support plate, a connection member and the movable part may be connected and fixed at the top and bottom of the mass, respectively, and the support plate may be arranged between the movable part and the connection member. 
         [0017]    The elastic member may be a coil spring, and the coil spring may have a large enough diameter to make contact between the movable part and the connection member. 
         [0018]    The mass may be separated into two parts on the basis of the support plate, and a connection member may be connected and fixed at the top or bottom of the mass, and the movable part may be arranged on the connection member. 
         [0019]    The movable part may include: magnets generating magnetic flux; and a yoke collecting the magnetic flux generated from the magnets being arranged on the yoke at predetermined intervals. 
         [0020]    The movable part may be arranged above or under the support plate and fixed to the mass, and the coil part may be arranged on the top or bottom of the support plate and faces the movable part. 
         [0021]    The support plate may include non-magnetic materials. 
         [0022]    A flexible substrate may be arranged on the support plate so as to supply power to the coil part from an external source. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    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: 
           [0024]      FIG. 1  is a partially exploded view illustrating a linear vibration motor according to an exemplary embodiment of the present invention; 
           [0025]      FIG. 2  is an exploded perspective view illustrating a linear vibration motor according to an exemplary embodiment of the present invention; 
           [0026]      FIG. 3  is a schematic cross-sectional view illustrating the internal structure of a linear vibration motor from which a mass is removed according to an exemplary embodiment of the present invention; 
           [0027]      FIG. 4  is a schematic perspective view illustrating a mass and a movable part according to an exemplary embodiment of the present invention; 
           [0028]      FIG. 5  is a side cross-sectional view schematically illustrating a linear vibration motor according to an exemplary embodiment of the present invention; 
           [0029]      FIG. 6  is a bottom perspective view illustrating a linear vibration motor according to an exemplary embodiment of the invention; 
           [0030]      FIG. 7  is a schematic cross-sectional view illustrating the internal structure of a linear vibration motor from which a mass is removed according to another exemplary embodiment of the present invention; 
           [0031]      FIG. 8  is a schematic perspective view illustrating a mass and a movable part according to another exemplary embodiment of the present invention; 
           [0032]      FIG. 9  is a schematic perspective view illustrating a mass and a movable part according another exemplary embodiment of the present invention; and 
           [0033]      FIGS. 10A and 10B  are plan views schematically illustrating a mass of a linear vibration motor performing a linear reciprocating motion inside a case. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0034]    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 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. In the drawings, the shapes and dimensions may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components 
         [0035]      FIG. 1  is a partially exploded view illustrating a linear vibration motor according to an exemplary embodiment of the invention.  FIG. 2  is an exploded perspective view illustrating a linear vibration motor according to an exemplary embodiment of the invention. 
         [0036]      FIG. 3  is a schematic cross-sectional view illustrating the internal structure of a linear vibration motor from which a mass is removed according to an exemplary embodiment of the invention.  FIG. 4  is a schematic perspective view illustrating a mass and a movable part according to an exemplary embodiment of the invention. 
         [0037]      FIG. 5  is a side cross-sectional view schematically illustrating a linear vibration motor according to an exemplary embodiment of the invention.  FIG. 6  is a bottom perspective view illustrating a linear vibration motor according to an exemplary embodiment of the invention. 
         [0038]    Referring to  FIGS. 1 through 6 , a linear vibration motor according to this embodiment may include a case  12 , a movable part  40 , a coil part  55  and a support plate  50 . 
         [0039]    The case  12  has a cavity therein to receive internal components in the cavity. A mass  20  is received in the cavity. An electromagnetic force, generated between the coil part  55  and the movable part  40 , allows the mass  20  to move in a transverse direction inside the case  12 . 
         [0040]    The case  12  may be a rectangular parallelepiped. Here, the direction in which the rectangular parallelepiped has a large length is referred to as the longitudinal direction, while the direction in which it has a short length is referred to as the transverse direction. However, when the case  12  is a cube, the longitudinal direction and the transverse direction are the same. 
         [0041]    The longitudinal length of the case  12  may be larger to increase the horizontal displacement of the mass  20 . 
         [0042]    The movable part  40  generates a magnetic field inside the case  12  and moves in the transverse direction while being secured to the mass  20 . 
         [0043]    The movable part  40  includes a magnet  44  generating magnetic flux and a yoke  42  collecting the magnetic flux generated from the magnet  44 . 
         [0044]    The magnet  44  may include one or a plurality of magnets. A plurality of magnets may be placed on the yoke  42  at predetermined intervals. 
         [0045]    The cavity of the case  12  may be separated into two parts in the vertical direction by a support plate  50 . The two parts, divided by the support plate  50 , are not necessarily equal to each other and can vary in design according to the distance between the movable part  40  and the coil part  55 . 
         [0046]    The movable part  40  and the coil part  55  may include various arrangements while interposing the support plate  50  therebetween so as to generate an electromagnetic force by which the mass  20  can move in the transverse direction. 
         [0047]    Referring to  FIG. 3 , the movable part  40  is disposed above the support plate  50  and secured to the mass  20 . The coil part  55  is arranged on the top of the support plate  50  and faces the movable part  40 . 
         [0048]    The coil part  55  is arranged on the top of the support plate  50 . Here, a plurality of coil parts  55  may be arranged to increase an electromagnetic force generated between the movable part  40  and the coil parts  55 . 
         [0049]    When AC power is applied to the coil part  55  from an external source, the direction of current flowing through the coil part  55  changes. Here, as the direction of the current changes, the movable part  40  starts to move right and left in the transverse direction. Since the mass  20  is secured to the movable part  40 , the mass  20  moves in the transverse direction in conjunction with the movable part  40  that is moving in the transverse direction. 
         [0050]    An elastic member  60  is arranged between the case  12  and the mass  20 . The elastic member  60  may use a spring such as a coil spring, a torsion spring or a plate spring. 
         [0051]    In order to increase utilization of internal space of the case  12 , as shown in  FIG. 4 , the mass  20  is separated into two parts on the basis of the support plate  50  in the case  12 . Since the mass  20  has a smaller length than the case  12 , the mass  20  can freely move inside the case  12 . 
         [0052]    Referring to  FIG. 4 , the movable part  40  and a connection member  26  are connected and fixed at the top and bottom of the mass  20 , respectively. Further, the support plate  50  is arranged between the movable part  40  and the connection member  26 . 
         [0053]    The connection member  26  and the mass  20  may be formed of the same or different material. When the connection member  26  and the mass  20  are formed of the same material, they may form a single body. 
         [0054]    The movable part  40  and the connection member  26  may have a smaller length than the longitudinal length of the mass  20  so that a space is formed at both ends of the mass  20  to receive the elastic member  60  therein. 
         [0055]    The elastic member  60  may be formed of a coil spring encompassing the support plate  50 . Here, the coil spring may have a large enough diameter to make contact with the movable part  40  and the connection member  26 . 
         [0056]    As the coil spring increases in diameter, points of support between the mass  20  and the elastic member  60  are widened, thereby ensuring the stable movement of the mass  20  in the transverse direction. 
         [0057]    Preferably, the support plate  50  may be formed of non-magnetic materials so as not to be affected by the magnet  44  of the movable part  40  located above the support plate  50 . Here, since the magnet  44  is distant from the base  14  formed of magnetic materials while interposing the support plate  50 , formed of non-magnetic materials, therebetween, the magnet  44  may be prevented from moving down toward the base  14 . 
         [0058]    A flexible substrate  56  may be disposed on the support plate  50  to supply external power to the coil part  55 . The linear vibration motor according to this embodiment is connected to an external substrate through a contact spring  18  to receive power from an outer source. The external power, being supplied through the contact spring  18 , moves to the coil part  55  of the support plate  50  through the flexible substrate  56 . 
         [0059]    The flexible substrate  56  is connected to the outside of the case  12  through a substrate passing hole  16  formed in the case  12  at a position corresponding to the support plate  50 , and as shown in  FIG. 6 , extends to the contact spring  18  located under the base  14 . 
         [0060]      FIG. 7  is a schematic cross-sectional view illustrating the internal structure of a linear vibration motor from which a mass is removed according to another exemplary embodiment of the invention.  FIG. 8  is a schematic perspective view illustrating a mass and a movable part according to another exemplary embodiment of the invention. 
         [0061]    Referring to  FIGS. 7 and 8 , a specific configuration is illustrated in which the coil part  55  is arranged on the bottom of the support plate  50 . 
         [0062]    A linear vibration motor according to an exemplary embodiment of the invention, shown in  FIGS. 7 and 8 , is identical to the linear vibration motor, shown in  FIGS. 3 and 4 , except that the coil part  55  is arranged on the bottom of the support plate  50  and faces the movable part  40 . 
         [0063]    Therefore, the detailed description of the linear vibration motor according to the embodiment, shown in  FIGS. 7 and 8 , will be replaced by the description of the linear vibration motor, illustrated with reference to  FIGS. 3 and 4 . 
         [0064]      FIG. 9  is a schematic perspective view illustrating a mass and a movable part according another exemplary embodiment of the invention. 
         [0065]    Referring to  FIG. 9 , the mass  20  of the linear vibration motor, shown in  FIG. 9 , is separated into two parts on the basis of the support plate  50  (see  FIGS. 10A and 10B ). The connection member  26  is connected and fixed at the top or bottom of the mass  20 , and the movable part  40  is arranged on the connection member  26 . 
         [0066]    Since the other components of the linear vibration motor, shown in  FIG. 9 , may be the same or similar components of the above-described embodiments, a detailed description thereof will be omitted. The way in which power is supplied to coils can be easily determined by a person skilled in the art. 
         [0067]      FIGS. 10A and 10B  are plan views schematically illustrating a mass of a linear vibration motor that performs a linear reciprocating motion within a case. 
         [0068]    The movement of a linear vibration motor according to an exemplary embodiment of the invention will be described in brief with reference to  FIGS. 10A and 10B . A linear vibration motor generating linear vibration according to an exemplary embodiment of the invention is provided on a board of a mobile phone. Here, power flows along the flexible substrate  56  through the contact spring  18  toward the coil part  55  on the support plate  50 . 
         [0069]    Here, since AC power is applied as the external power, the direction of current flowing through the coil part  55  is reversed. The movable part  40 , to which a force is applied according to the direction of the current flowing through the coil part  55 , moves right and left in the transverse direction. 
         [0070]    The movement of the movable part  40  causes a movement of the mass  20  secured to the movable part  40 . When the mass  20  horizontally moves right and left and alternates between tension and compression, the elastic member  60  transmits vibration to the case  12  and the mobile phone including the case  12 . 
         [0071]    As set forth above, according to exemplary embodiments of the invention, since a mass of a linear vibration motor generates vibration in a transverse direction, the thickness of the terminal is not limited. Accordingly, the thickness of the terminal can be reduced. 
         [0072]    The terminal having the reduced thickness can increase in length to ensure horizontal displacement of the mass, thereby increasing the amount of vibration. 
         [0073]    Furthermore, since the mass can be designed to fit the entire space of the case, space utilization can be increased. Since a spring can be arranged inside the mass along the transverse direction, the diameter of the spring can be increased. 
         [0074]    In addition, the spring increases in diameter to widen points of support between the mass and the spring, so that the mass can stably move in the transverse direction. 
         [0075]    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.