Abstract:
There is provide a flat-type vibration motor capable of significantly reducing the generation of injection burrs during an injection molding process of an injection molding material, the flat-type vibration motor according to the present invention including: a rotor including a first substrate having a circuit pattern formed on a surface thereof and a holder coupled to the first substrate by injection molding; and a shaft including the rotor rotatably coupled thereto and forming a rotational axis of the rotor, wherein the circuit pattern may include a sealing pattern formed along an outline of the holder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 10-2011-0141639 filed on Dec. 23, 2011, 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 flat-type vibration motor, and more particularly, to a flat-type vibration motor capable of significantly reducing the generation of injection burrs during an injection molding process of an injection molding material. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, various types of vibration generation devices have been mounted in portable electronic devices such as portable phones, game machines, portable information terminals, and the like, in order to prevent inconvenience to surrounding people due to audible sounds therefrom. 
         [0006]    In addition, generally, since a flat-type vibration motor may sufficiently vibrate in a state in which miniaturization, lightness, and slimness are implemented, the flat-type vibration motor has been widely used as a means for notifying a user of call reception in a portable terminal. 
         [0007]    Meanwhile, recently, a touch screen in which signals are simply input by touching characters or other icons displayed on a screen, a display device of the portable terminal, with a hand or a pen has been mainly used. 
         [0008]    In addition, in order to allow a user to feel a touch sense at the time of touching a screen of the portable terminal, an apparatus for generating vibrations may be installed in the portable terminal. 
         [0009]    As an apparatus for generating vibrations, various vibration motors are used as a vibration source, wherein the vibration motor may be divided into a flat-type vibration motor and a cylinder-type vibration motor according to a shape thereof and be divided into a brush-type vibration motor and a brushless-type vibration motor according to the presence and absence of a brush. 
         [0010]    Among them, since a brush flat-type vibration motor may be manufactured to have a relatively small thickness, the brush flat-type vibration motor may be advantageous for miniaturization of a mobile phone, such that the brush flat-type vibration motor is now widely used. 
         [0011]    Generally, in the flat-type vibration motor, a rotor having a coil and a weight body eccentrically disposed on a substrate rotates about a rotational shaft, to generate vibrations. In this case, the rotational shaft and the rotor are coupled to each other by a holder formed of a resin material on the substrate. 
         [0012]    This holder may be coupled to the substrate through injection molding. However, in the flat-type vibration motor according to the related art, an injection molding material may be leaked to the outside of a mold during an injection molding process of forming this holder. The reason is that a gap is formed in a portion in which the substrate and the mold interlock with each other due to a circuit pattern formed on the substrate. 
         [0013]    Since the injection molding material leaked to the outside of the mold through this gap may spread across the entire substrate, the leaked injection molding material is interposed between the substrate and the coil or the weight body, causing the coil or the weight body to be seated inaccurately. 
         [0014]    Therefore, a structure of a flat-type vibration motor capable of suppressing leakage of an injection molding material has been required. 
       Related Art Document  
     (Patent Document 1) Korean Patent Laid-Open Publication No. 2011-0011417 
     SUMMARY OF THE INVENTION 
       [0015]    An aspect of the present invention provides a flat-type vibration motor capable of preventing an injection molding material from being leaked to the outside of a mold to thereby spread on a substrate during a manufacturing process according to the present invention. 
         [0016]    According to an aspect of the present invention, there is provided a flat-type vibration motor including: a rotor including a first substrate having a circuit pattern formed on a surface thereof and a holder coupled to the first substrate by injection molding; and a shaft including the rotor rotatably coupled thereto and forming a rotational axis of the rotor, wherein the circuit pattern may include a sealing pattern formed along an outline of the holder. 
         [0017]    The rotor may include a winding coil attached to the surface of the first substrate; and a weight body eccentrically attached to the surface of the first substrate. 
         [0018]    The rotor may further include a bearing interposed between the holder and the shaft to rotatably support the shaft. 
         [0019]    The flat-type vibration motor may further include a bracket including a shaft fixed to a central portion thereof and a second substrate and a magnet that are attached to an upper surface thereof; a case covering an upper portion of the bracket and providing an inner space; and a brush having one end fixed to a second substrate and the other end electrically connected to the rotor. 
         [0020]    The holder may be extended toward one end portion of the first substrate to thereby be coupled to the first substrate while enclosing a side surface of the first substrate. 
         [0021]    The rotor may include a winding coil attached to the surface of the first substrate, and the circuit pattern may be electrically connected to the winding coil. 
         [0022]    The sealing pattern may be a dummy pattern only formed in a vicinity of the holder. 
         [0023]    According to another aspect of the present invention, there is provide a flat-type vibration motor including: a first substrate including a weight body coupled thereto and a circuit pattern formed on a surface thereof; and a holder coupled to the first substrate, wherein the circuit pattern may be disposed between the holder and the first substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    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: 
           [0025]      FIG. 1  is a cross-sectional view of a flat-type vibration motor according to an embodiment of the present invention; 
           [0026]      FIG. 2  is a top perspective view showing a rotor of the flat-type vibration motor shown in  FIG. 1 ; 
           [0027]      FIG. 3  is a bottom perspective view of  FIG. 2 ; and 
           [0028]      FIG. 4  is a partially enlarged plane view of part A of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0029]    Hereinafter, embodiments of the present invention will 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. In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. 
         [0030]      FIG. 1  is a cross-sectional view of a flat-type vibration motor according to an embodiment of the present invention,  FIG. 2  is a top perspective view showing a rotor of the flat-type vibration motor shown in  FIG. 1 , and  FIG. 3  is a bottom perspective view of  FIG. 2 . 
         [0031]    A flat-type vibration motor  100  according to the embodiment of the present invention may include a bracket  110 , a case  120 , a rotor  130 , and a brush  150 . 
         [0032]    The bracket  110  may support other components of the vibration motor  100  and be assembled with the case  120  to provide a predetermined inner space. To this end, the bracket  110  may have a disk shape having a predetermined thickness and include a shaft  114  fixed to a central portion thereof and a lower substrate  116 , a second substrate, and a magnet  118  that are attached on an upper surface thereof. 
         [0033]    The bracket  110  may have a burring part  112  formed thereon and protruding upwardly to fix the shaft  114  thereto. Therefore, the shaft  114  may be press-fitted into the burring part  112  at a lower end thereof to thereby be fixedly coupled to the bracket  110 . 
         [0034]    The lower substrate  116  may supply power to a winding coil  138  to be described below. To this end, the lower substrate  116  may include a terminal part (not shown) electrically connected to external power. 
         [0035]    The lower substrate  116  may be attached to the upper surface, that is, an inner surface of the bracket  110 . In this case, the lower substrate  116  may be electrically connected to one end of the brush  150  to be described below. 
         [0036]    Meanwhile, although the case in which the lower substrate  116  and the bracket  110  are individually formed and then be coupled to each other is shown in the drawings, the present invention is not limited thereto, and various embodiments thereof may be provided. For example, the bracket and the lower substrate maybe manufactured integrally with each other to configure one component. 
         [0037]    The magnet  118  may be provided to generate a magnetic field having a predetermined amount of strength to rotate the rotor  130  by interaction with the winding coil  138 . The magnet  118  may be adhered to an upper portion of the lower substrate  116  through an adhesive member, or the like. 
         [0038]    In addition, the magnet  118  may be annularly disposed based on the shaft  114  fixed to the bracket  110  in a vertical manner, and may be a permanent magnet alternately magnetized so as to have a plurality of magnetic poles in a circumferential direction thereof. In this case, the magnet  118  maybe attached to face the winding coil  138  to be described below. 
         [0039]    The case  120 , a member protecting the vibration motor  100  from the outside and providing a rotational space of the rotor  130 , that is, the inner space, maybe coupled to the bracket  110  in such a manner that the case covers an upper portion of the bracket  110  to provide the inner space. 
         [0040]    Here, the case  120  may be formed of a magnetic material having a high degree of permeability such that magnetic paths of magnetic flux generated in the magnet  118  and the winding coil  138  of the rotor  130  may be formed, while having strong strength such that the rotor may be not restricted by case deformation due to external force. 
         [0041]    In addition, in the center of an inner portion of the case  120 , a friction reducing member (not shown) capable of directly contacting the rotor  130  to reduce friction and noise may be provided. 
         [0042]    Meanwhile, the case in which the bracket  110  is formed to have the disk shape, and the case  120  has a cylindrical shape corresponding thereto and is coupled to the bracket  110 , thereby providing the inner space is described by way of example in the embodiment. However, the present invention is not limited thereto, but may have any shape as needed as long as the rotor  130  may smoothly rotate in the inner space. 
         [0043]    The rotor  130 , provided to rotate eccentrically to generate vibrations, may be configured to include an upper substrate  132 , a first substrate, a holder  136 , the winding coil  138 , a weight body  140 , and a bearing  142 . 
         [0044]    The upper substrate  132  is provided to support components of the rotor  130  and transmit power to the winding coil  138  and may include a through-hole formed in a central portion thereof such that the shaft  114  and the bearing  142  may be inserted thereinto. 
         [0045]    Here, a commutator  134  may be divided into a plurality of segments, and the plurality of segments of the commutator  134  may be formed in an annular manner based on the through-hole in a lower surface of the upper substrate  132 . The commutator  134  may serve to contact the brush  150  to be described below, and to transmit power to the winding coil  138 . The commutator  134  may be formed by a pattern printing method, a plating method, or the like. 
         [0046]    Further, the upper substrate  132  according to the embodiment may include a circuit pattern  132   a  formed on an upper surface thereof. The circuit pattern  132   a  may be used as a path electrically connecting the commutator  134  and the winding coil  138 . 
         [0047]    Particularly, the circuit pattern  132   a  according to the embodiment of the present invention may include a sealing pattern  132   b  formed on the upper substrate  132  to have a shape corresponding to an outline of a holder  136  to be described below. 
         [0048]      FIG. 4 , an exploded plan view of part A of  FIG. 2 , shows the upper surface of the upper substrate  132  to which the holder  136  according to the embodiment of the present invention is coupled. Referring to  FIGS. 1 to 4 , the sealing pattern  132   b  according to the embodiment of the present invention may be continuously formed along a contact surface between the holder  136  and the upper substrate  132  while being interposed therebetween on the upper surface of the upper substrate  132 . 
         [0049]    As the sealing pattern  132   b  is interposed between the holder  136  and the upper substrate  132  as described above, since a gap is not formed in the contact surface between the holder  136  and the upper substrate  132 , the holder  136  and the upper substrate  132  may be firmly coupled to each other. 
         [0050]    A configuration of the circuit pattern  132   a  as described above is provided in order to prevent an injection molding material from being leaked to the outside of a mold during a process of coupling the holder  136  to the upper substrate  132 . A detailed description thereof will be provided in the following description of the holder  136 . 
         [0051]    The holder  136  may be provided in order to fix the bearing  142  to the upper substrate  132 . 
         [0052]    Therefore, the holder  136  may include a groove therein such that the bearing  142  is insertedly fixed thereto. 
         [0053]    The holder  136  may not be formed on the entire area of the upper substrate  132  but be partially formed in the vicinity of an area of the upper substrate  132  into which the bearing  142  is inserted. 
         [0054]    Further, in order to firmly fix the holder  136  to the upper substrate  132 , the holder  136  may be extended toward one end portion of the upper substrate  132  to enclose a side surface of the upper substrate  132 . 
         [0055]    Meanwhile, the bearing  142  according to the embodiment of the present invention may be lengthily formed in a length direction of the shaft  114  so as to be stably coupled to the shaft  114 . Therefore, the holder  136  supporting the bearing  142  may have a height corresponding to a length of the bearing  142 . 
         [0056]    More specifically, the holder  136  according to the embodiment of the present invention may be formed in such a manner that a portion thereof formed in the vicinity of the bearing  142  protrudes from the upper surface of the upper substrate  132  to a height corresponding to the length of the bearing  142  in order to cover the length of the bearing  142 . In addition, the holder  136  may penetrate through the through-hole of the upper substrate  132  to protrude downwardly of the upper substrate  132 . 
         [0057]    The holder  136  according to the embodiment of the present invention as described above may be fixedly coupled to the upper substrate  132  through an injection molding process. 
         [0058]    That is, the holder  136  may be formed by a method of disposing the upper substrate  132  in a mold, injecting a resin solution into the mold, and hardening the injected resin solution, and at time same time, the holder  136  may be coupled to the upper substrate  132 . 
         [0059]    Meanwhile, during this process, the resin solution injected into the mold may be leaked to the outside of the mold as in the related art. However, in the vibration motor  100  according to the embodiment of the present invention, leakage of the resin solution to the outside of the mold may be suppressed using the circuit pattern  132   a  formed on the upper substrate  132 . 
         [0060]    As described above, in the upper substrate  132  according to the embodiment of the present invention, the sealing pattern  132   b  of the circuit pattern  132   a  may be continuously formed along the outline of the holder  136 . Therefore, when the upper substrate  132  is disposed in the mold during the injection molding process, the mold may interlock with the sealing pattern  132   b  of the upper substrate  132 . 
         [0061]    Accordingly, the gap may not be formed between the upper substrate  132  and the mold, such that leakage of the injection molding material to the outside of the mold during the injection molding process may be prevented. 
         [0062]    When power is applied through the commutator  134  contacting the brush  150 , the winding coil  138 , provided to generate an electromagnetic field having a predetermined amount of strength during the application of power, may generate the electromagnetic field and generate electromagnetic force through interaction with the magnetic field generated in the magnet  118 , thereby rotating the rotor  130 . 
         [0063]    Here, at least one winding coil  138  may be attached to the upper surface of the upper substrate  132  using an adhesive member such as an adhesive or a double-side tape. 
         [0064]    The weight body  140  is provided to add a predetermined mass such that the rotor  130  may rotate eccentrically, and at least one weight body  140  may be attached to the upper surface of the upper substrate  132  using the above-mentioned adhesive member. 
         [0065]    The weight body  140  may be formed of a metal having a high specific gravity such as tungsten, or the like. 
         [0066]    The weight body  140  may be disposed on the outermost circumference of the rotor  130 . In this case, since an offset distance from the center of the shaft to the center of gravity of the rotor  130  increases, an amount of eccentricity may increase. 
         [0067]    The bearing  142 , rotatably supported by the shaft  120  to rotate, may be inserted into the holder  136 . In this case, the bearing  142  may be fixedly coupled to the holder  136  while being forcedly fitted thereto or be fixedly adhered to the holder  136  using an adhesive. 
         [0068]    In the rotor  130  according to the embodiment of the present invention configured as described above, the holder  136  may be coupled to the upper substrate  132  by the injection molding process in a state in which the winding coil  138  and the bearing  142  are not present. 
         [0069]    Therefore, defects such as damage or deformation of the winding coil  138  or the bearing  142 , by injection pressure and injection temperature during the injection molding process, or the like, may be prevented. 
         [0070]    In addition, in the vibration motor  100  according to the embodiment of the present invention, the injection molding process is performed using a strip or an array state of the upper substrate  132 , such that a plurality of holder-upper substrate assemblies may be formed in a one-time injection molding process. In this case, injection molding productivity may be increased (That is, manpower for injection molding may be decreased and injection molding products may be increased). 
         [0071]    The brush  150 , provided to apply power to the commutator  134 , may have one end fixedly coupled to the upper surface of the lower substrate  116  and the other end elastically contacting the commutator  134  formed on the lower surface of the upper substrate  132 . 
         [0072]    In the flat-type vibration motor according to the embodiment of the present invention configured as described above, since the holder is initially formed on the upper substrate by the injection molding process and then the winding coil and the bearing are attached, damage to or deformation of the winding coil or the bearing due to a high injection temperature and injection pressure may be prevented. 
         [0073]    In addition, according to the present invention, since the holder is not formed on the entire area of the upper substrate but formed to have a significantly small size in a range in which the bearing may be fixed, material costs may be reduced. 
         [0074]    Further, according to the present invention, the circuit pattern of the upper substrate may have a shape corresponding to the outline of the holder. Therefore, since the mold is firmly interlocked with the circuit pattern of the upper substrate during the injection molding process, the gap may not be formed between the upper substrate and the mold, such that leakage of the injection mold material to the outside of the mold during the injection molding process may be prevented. 
         [0075]    The flat-type vibration motor according to the present invention as described above is not limited to the above-mentioned embodiments, but various modifications may be made by those skilled in the art without departing from the spirit and scope of the present invention. 
         [0076]    For example, the case in which the circuit pattern is formed to correspond to the outline of the holder is described byway of example in the above-mentioned embodiments. However, the present invention is not limited thereto. That is, the present invention may be variously applied. For example, a dummy pattern may be formed along the outline of the holder, separately from the circuit pattern. 
         [0077]    In addition, although the case in which the circuit pattern is formed to correspond to the entire outline of the holder is described by way of example in the above-mentioned embodiments, the present invention is not limited thereto. That is, the circuit pattern may be partially only formed in a portion in which the winding coil and the weight body are disposed. 
         [0078]    In the case in which the circuit pattern is configured as described above, the resin solution may be partially leaked during the injection molding process in a portion in which the mold does not interlock with the circuit pattern. However, since the leaked resin solution may spread in a direction approximately opposite to that in which the winding coil or the weight body is disposed, substantially, the leaked resin solution does not directly affect the winding coil or the weight body. 
         [0079]    Further, although the case in which the sealing pattern has a uniform width is described by way of example in the above-mentioned embodiments, the present invention is not limited thereto. That is, the sealing pattern may have various thicknesses as long as it may be formed along the outline of the holder, and a shape of the sealing pattern may be variously modified according to positions. 
         [0080]    Further, although the case of the upper substrate and the holder provided in the flat-type vibration motor is described by way of example in the above-mentioned embodiments, the present invention is not limited thereto, but may be variously used in any electronic device manufactured by coupling an injection molding material to a substrate through the injection molding process. 
         [0081]    As set forth above, in the flat-type vibration motor according to the present invention, since the holder is first formed on the upper substrate by the injection molding process and then the winding coil and the bearing are attached thereon, damage or deformation of the winding coil or the bearing by high injection temperature and injection pressure can be prevented. 
         [0082]    In addition, according to the present invention, since the holder is not formed in the entire area of the upper substrate but formed to be significantly small within a range of area in which the bearing may be fixed, material costs may be reduced. 
         [0083]    Further, according to the present invention, the circuit pattern of the upper substrate may have a shape corresponding to the outline of the holder. Therefore, since the mold is firmly interlocked with the circuit pattern of the upper substrate during the injection molding process of the holder, the gap may not be formed between the upper substrate and the mold, such that leakage of the injection mold material to the outside of the mold during the injection molding process can be prevented. 
         [0084]    While the present invention has been shown and described in connection with the 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.