Abstract:
A spindle motor is provided, the motor comprising: a base plate, a PCB on the base plate, a bearing assembly arranged on the base plate, a stator coupled to a periphery of the bearing assembly, a rotor rotationally coupled to the bearing assembly, the rotor including a yoke and a magnet, and a rotation shaft rotationally coupled to the bearing assembly. The base plate includes a planar portion and a protruding portion arranged along with a periphery of the yoke, the protruding portion being apart from the yoke. The base plate is partially covered with the PCB in a region where the stator is arranged. And, a height from the planar portion to an upper surface of the protruding portion is smaller than a height from the planar portion to a lower surface of the periphery of the yoke.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/054,333, filed Oct. 15, 2013, which is a continuation of U.S. patent application Ser. No. 13/299,661, filed Nov. 18, 2011, which claims the benefit under 35 U.S.C. §119 of Korean Application No. 10-2010-0115160, filed Nov. 18, 2010, which are hereby incorporated by reference in their entirety. 
     
    
     BACKGROUND 
       [0002]    The present disclosure generally relates to a spindle motor. 
         [0003]    A spindle motor performs a function of rotating a disk to enable an optical pickup which linearly reciprocates in an optical disk drive ODD and a hard disk to read a large amount of data recorded on the disk. The ODDs have been recently developed to stably rotate an optical disk at a high speed. 
         [0004]    The ODD includes a spindle motor for rotating an optical disk at a high speed, an optical pickup module for reading out data from a disk rotating at a high speed or recording the data on the disk, and a stepping motor for driving the optical pickup module. 
         [0005]    The spindle motor rotating the optical disk at a high speed includes a bearing rotationally supporting a rotation shaft, a bearing housing accommodating the bearing, a stator secured at a periphery of the bearing housing, a rotor rotationally accommodated on the bearing, a base plate fixing the bearing housing and a circuit substrate arranged at an upper surface of the base plate. 
         [0006]    A gap is formed between an upper surface of the base plate and the stator according to a conventional spindle motor to disadvantageously introduce foreign objects. In order to reduce the gap formed between the stator and the upper surface of the base plate, the circuit substrate arranged on the upper surface of the base plate is unnecessarily extended to a bottom surface of the stator. If the circuit substrate is extended to between the stator and the base plate, inflow of foreign objects into the base plate and the stator may be reduced to a certain degree. However, a problem occurs in which an area of the high-priced circuit substrate disadvantageously increases to increase a manufacturing cost of the spindle motor. 
       BRIEF SUMMARY 
       [0007]    Exemplary embodiments of the present disclosure provide a spindle motor configured to reduce a manufacturing cost by dispensing with unnecessary extension of a circuit substrate into between a stator and a base plate and by preventing foreign objects from entering the stator and the base plate. 
         [0008]    In one general aspect of the present disclosure, there is provided a spindle motor, comprising: a base plate; a PCB on the base plate; a bearing assembly arranged on the base plate; a stator coupled to a periphery of the bearing assembly; a rotor rotationally coupled to the bearing assembly, the rotor including a yoke and a magnet; and a rotation shaft rotationally coupled to the bearing assembly, wherein the base plate includes a planar portion and a protruding portion arranged along with a periphery of the yoke, the protruding portion being apart from the yoke, wherein the base plate may be partially covered with the PCB in a region where the stator is arranged, and wherein a height from the planar portion to an upper surface of the protruding portion may be smaller than a height from the planar portion to a lower surface of the periphery of the yoke. 
         [0009]    In some exemplary of the present invention, the PCB may include an exposure unit exposing a part of the base plate opposite to the stator, and the protruding portion prevents foreign objects from entering to the exposure unit. 
         [0010]    In some exemplary of the present invention, the base plate may include a first through hole to be coupled to the bearing assembly, and the PCB includes a second through hole formed at a position corresponding to that of the first through hole and partially opened toward the protruding portion. 
         [0011]    In some exemplary of the present invention, the protruding portion may include a shape of a curved line when viewed in a top plane. 
         [0012]    In some exemplary of the present invention, the protruding portion may have the same curvature as that of a core of the stator. 
         [0013]    In some exemplary of the present invention, the height from the planar portion to the upper surface of the protruding portion may be the same as thickness of the PCB. 
         [0014]    In some exemplary of the present invention, the protruding portion may protrude with a right angle relative to the planar portion. 
         [0015]    In some exemplary of the present invention, the height from the planar portion to the upper surface of the protruding portion may be higher than the thickness of the PCB. 
         [0016]    In some exemplary of the present invention, the protruding portion may protrude with an obtuse angle relative to the planar portion. 
         [0017]    In some exemplary of the present invention, the protruding portion may protrude with an acute angle relative to the planar portion. 
         [0018]    In some exemplary of the present invention, the protruding portion may be integrally formed with the planar portion. 
         [0019]    In some exemplary of the present invention, the protruding portion may be integrally formed with the planar portion by bending a part of the base plate. 
         [0020]    In some exemplary of the present invention, the protruding portion may include a semi-circular shape when viewed in a top plane. 
         [0021]    In some exemplary of the present invention, the bearing assembly may include a bearing housing and a bearing inserted into the bearing housing, the stator may include a core including radially formed core pieces and a coil wound on the core pieces, and the rotor may include the magnet opposite to the core pieces and the yoke fixing the magnet and coupled to the rotation shaft inserted into the bearing. 
         [0022]    In some exemplary of the present invention, the PCB may be formed with a through hole through which the bearing assembly passes, and a diameter of the through hole may be larger than that of the bearing assembly, and the through hole may be partially opened. 
         [0023]    In another general aspect of the present disclosure, there is provided a spindle motor, comprising: a base plate; a PCB on the base plate; a bearing assembly arranged on the base plate; a stator coupled to a periphery of the bearing assembly; a rotor rotationally coupled to the bearing assembly, the rotor including a yoke and a magnet; and a rotation shaft rotationally coupled to the bearing assembly, wherein the yoke may include an upper plate and a lateral plate, wherein the base plate may include a planar portion and a protruding portion arranged along with the lateral plate of the yoke, and wherein the protruding portion may be configured to have a gap between the protruding portion and a lower surface of the lateral plate of the yoke. 
         [0024]    In some exemplary of the present invention, the PCB may be partially arranged on the base plate in a region where the rotor is arranged. 
         [0025]    In some exemplary of the present invention, the base plate may include a first through hole to be coupled to the bearing assembly, and the PCB may include a second through hole formed at a position corresponding to that of the first through hole and partially opened toward the protruding portion. 
         [0026]    In some exemplary of the present invention, the protruding portion may include a shape of a curved line when viewed in a top plane. 
         [0027]    In some exemplary of the present invention, the protruding portion may have the same curvature as that of a core of the stator. 
         [0028]    In some exemplary of the present invention, a height from the planar portion to an upper surface of the protruding portion may be the same as thickness of the PCB. 
         [0029]    In some exemplary of the present invention, a height from the planar portion to an upper surface of the protruding portion may be higher than the thickness of the PCB. 
         [0030]    In some exemplary of the present invention, the protruding portion may protrude with an obtuse angle relative to the planar portion. 
         [0031]    In some exemplary of the present invention, the protruding portion may protrude with an acute angle relative to the planar portion. 
         [0032]    In some exemplary of the present invention, the protruding portion may be integrally formed with the planar portion. 
         [0033]    In some exemplary of the present invention, the protruding portion may be integrally formed with the planar portion by bending a part of the base plate. 
         [0034]    In some exemplary of the present invention, the protruding portion may include a semi-circular shape when viewed in a top plane. 
         [0035]    In some exemplary of the present invention, the bearing assembly may include a bearing housing and a bearing inserted into the bearing housing, the stator may include a core including radially formed core pieces and a coil wound on the core pieces, and the rotor may include the magnet opposite to the core pieces and the yoke fixing the magnet and coupled to the rotation shaft inserted into the bearing. 
         [0036]    In some exemplary of the present invention, the PCB may be formed with a through hole through which the bearing assembly passes, and a diameter of the through hole is larger than that of the bearing assembly, and the through hole may be partially opened. 
         [0037]    The spindle motor according to the exemplary embodiments of the present disclosure has an advantageous effect in that an exposure unit is formed at a part of a PCB interposed between a base plate and a core of a stator to reduce a manufacturing cost of the PCB, and foreign objects introduced through the exposure unit is prevented by a foreign object inflow prevention fence formed at the base plate to avoid the spindle motor from being polluted by the foreign objects. 
         [0038]    Additional advantages, objects, and features of the disclosure will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the disclosure. The objectives and other advantages of the disclosure may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0039]    It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    Accompanying drawings are included to provide a further understanding of arrangements and embodiments of the present disclosure and are incorporated in and constitute a part of this application. In the following drawings, like reference numerals refer to like elements and wherein: 
           [0041]      FIG. 1  is a perspective view of a spindle motor according to an exemplary embodiment of the present disclosure; 
           [0042]      FIG. 2  is a cross-sectional view taken along line  1 - 1 ′ of  FIG. 1 ; 
           [0043]      FIG. 3  is a plane view illustrating a spindle motor of  FIG. 1  removed of a rotation shaft and a rotor; 
           [0044]      FIG. 4  is a partially enlarged perspective view illustrating a spindle motor of  FIG. 3  removed of a stator; and 
           [0045]      FIG. 5  is a lateral view of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0046]    Hereinafter, exemplary embodiments of the present disclosure are described in detail with reference to the accompanying drawings. In the drawings, sizes or shapes of constituent elements may be exaggerated for clarity and convenience. 
         [0047]    Particular terms may be defined to describe the disclosure in the best mode as known by the inventors. Accordingly, the meaning of specific terms or words used in the specification and the claims should not be limited to the literal or commonly employed sense, but should be construed in accordance with the spirit and scope of the disclosure. The definitions of these terms therefore may be determined based on the contents throughout the specification. The meaning will be clear from the context of the description. Like numbers refer to like elements throughout, and explanations that duplicate one another will be omitted. 
         [0048]    As may be used herein, the terms “substantially” and “approximately” provide an industry-accepted tolerance for its corresponding term and/or relativity between items. Such an industry-accepted tolerance ranges from less than one percent to ten percent and corresponds to, but is not limited to, component values, angles, et cetera. 
         [0049]    Any reference in this specification to “one embodiment,” “an embodiment,” “exemplary embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to affect such feature, structure, or characteristic in connection with others of the embodiments. 
         [0050]      FIG. 1  is a perspective view of a spindle motor according to an exemplary embodiment of the present disclosure,  FIG. 2  is a cross-sectional view taken along line  1 - 1 ′ of  FIG. 1 ,  FIG. 3  is a plane view illustrating a spindle motor of  FIG. 1  removed of a rotation shaft and a rotor,  FIG. 4  is a partially enlarged perspective view illustrating a spindle motor of  FIG. 3  removed of a stator, and  FIG. 5  is a lateral view of  FIG. 1 . 
         [0051]    Referring to  FIGS. 1 to 5 , a spindle motor  800  includes a bearing assembly  100 , a stator  200 , a rotation shaft  300 , a rotor  400 , a base plate  500  and a PCB Printed Circuit Board,  700 . In addition, the spindle motor  800  may further include a clamp  600 . 
         [0052]    The bearing assembly  100  includes a bearing housing  110  and a bearing  120 . The bearing housing  110  takes a shape of a hollow hole-formed cylinder, for example, and the bearing housing  110  is formed at an upper corner with a staircase sill  115  for securing a core described later. The bearing housing  110  is protruded at a rear surface with a coupling lug  117  for being coupled with the base plate  500 , described later. 
         [0053]    The bearing housing  110  is arranged at a bottom surface with a support plate  119  for supporting a bottom end of the rotation shaft  300 , described later, and a portion contacting a bottom end of the rotation shaft  300  in the support plate  119  is formed with a thrust bearing  119   a.    
         [0054]    The bearing  120  takes a shape of a cylinder inserted into the bearing housing  110 , and is formed with a rotation shaft hole for being coupled with the rotation shaft. In the exemplary embodiment of the present disclosure, the bearing  120  may include an oil sintered impregnation bearing. 
         [0055]    The stator  200  includes a core  210  and a coil  220 . The core  210  is formed by stacking a plurality of iron pieces each having an opening, and secured to the staircase sill  115  of the bearing housing  100 . In the exemplary embodiment of the present disclosure, the core  210  includes core units  212 , where the core units  212  are formed by being radially protruded, and the core  210  including the core units  212  takes a shape of a disk when viewed in a top plane. 
         [0056]    In the exemplary embodiment of the present disclosure, a part of the core  210  including the core units  212  may be arranged to protrude from an edge of the base plate  500 . The coil  220  is wound on the core unit  212  formed at the core  210 . 
         [0057]    The rotation shaft  300  is inserted into the rotation shaft hole of the bearing  120  at the bearing assembly  100 , and a bottom end of the rotation shaft  300  is brought into contact with the thrust bearing  119   a  supported by the support plate  119 . 
         [0058]    The rotor  400  includes a yoke  410  and a magnet  420 . In addition, the rotor  400  may further include a suction magnet  430 . The yoke  410  may include a yoke upper plate  412  and a yoke lateral plate  414 . 
         [0059]    The yoke upper plate  412 , when viewed from a top plane, takes a shape of a disk, and is centrally formed with a cylindrically shaped yoke burring unit  413  towards an upper surface of the yoke upper plate  412 . The yoke burring unit  413  is press-fitted into the rotation shaft  300 . 
         [0060]    The yoke lateral plate  414  is downwardly extended from the yoke upper plate  412  and a void is formed inside the yoke  410  by the yoke lateral plate  414  and the yoke upper plate  412 . 
         [0061]    The magnet  420  is formed along an inner lateral surface of the yoke lateral plate  414 , and a rotational force is generated on the yoke  410  and the rotation shaft  300  by attractive force and repulsive force generated a magnetic field generated by the coil  220  wound on the core unit  212  of the core  210  and a magnetic field generated by the magnet  420 . The yoke upper plate  412  of the yoke  410  is arranged with a clamp  600  for chucking an optical disk. 
         [0062]    Meantime, a suction magnet  430  may be arranged at any one place of an inner lateral surface of the yoke upper plate  412  and an upper surface of the core  210  opposite to the inner lateral surface of the yoke upper plate  412 . 
         [0063]    In the exemplary embodiment of the present disclosure, the suction magnet  430  may be arranged at the inner lateral surface of the yoke upper plate  412 , for example, and the suction magnet  430  arranged at the inner lateral surface pulls the core  210  using the magnetic force to stably rotate the rotor  400 . 
         [0064]    Referring to  FIGS. 2 ,  3  and  4  again, the base plate  500  is formed by processing a metal plate. The base plate  500  is formed with a through hole  502  corresponding to the hollow hole of the bearing housing  110  at the bearing assembly  100 , as shown in  FIG. 2 . 
         [0065]    The base plate  500  is formed with a lug  510  formed in a shape corresponding to the core  210  of the stator  200 , and the lug  510  may take a semi-disk semi-circular shape when viewed in a top plane. Thus, foreign objects can be initially prevented by the lug  510  from entering an interior of the spindle motor through a bottom surface of the core  210 . 
         [0066]    The PCB  700  is arranged at an upper surface of the base plate  500 , and is mounted with a variety of circuit elements, where the PCB  700  is electrically connected to the coil  220  which is a constituent element of the stator  200 . The PCB  700  is formed with a through hole  505  for preventing an interference with the bearing housing  110 . Size of the through hole  505  formed at the PCB  700  is larger than that of a through hole  502  formed at the base plate  505 . The through hole  505  of the PCB  700  is partially opened and the opened portion of the through hole  505  may be formed with a curvature. 
         [0067]    Referring to  FIGS. 2 and 5 , a bottom surface of the core  210  coupled to the bearing housing  110  of the bearing assembly  100  coupled to the base plate  500  is discrete from an upper surface of the base plate  500  at a predetermined gap, where various foreign objects such as dust, fine particles, oily dust and the like can be introduced into the base plate  500  and the bottom surface of the core  210 , and the foreign objects can be attached to the core  210 , the coil  220 , the bearing and the magnet  420 , and life of the spindle motor  800  can be greatly reduced by the foreign objects attached thereto. 
         [0068]    In order to prevent the foreign objects from introducing into the gap between the upper surface of the base plate  500  and the bottom surface of the core  210 , a partial area of the PCB  700  may be extended to be arranged on the lug  510  of the base plate  500 . 
         [0069]    In a case the PCB  700  covers the semi-disk lug  510  of the base plate  500 , the gap between the upper surface of the base plate  500  and the bottom surface of the core  210  is reduced as much as thickness of the PCB  700  to decrease inflow of the foreign objects. 
         [0070]    However, in a case the high-priced PCB  700  is unnecessarily extended to cover the lug  510  of the base plate  500 , a manufacturing cost of the spindle motor  800  is inevitably increased. 
         [0071]    In the exemplary embodiment of the present disclosure, the PCB  700  is formed with an exposure unit  710  that exposes the semi-disk lug  510  of the base plate  500  as illustrated in  FIG. 5 . The closed through hole  505  formed at the PCB  700  is opened by the exposure unit  710 . 
         [0072]    In the exemplary embodiment of the present disclosure, the frequently used “exposure unit” is defined by a portion exposing the base plate  500  that is formed by removing a part corresponding to a part opposite to the core  210  in the PCB  700  arranged on the base plate  500 . 
         [0073]    A portion corresponding to the semi-disk lug  510  is formed the by exposure unit with a void space not formed with the PCB  700 . In a case the exposure unit  710  exposing a part of the semi-disk shaped lug  510  of the base plate opposite to the core  210  is formed on the PCB  700 , an area of the PCB  700  is reduced whereby a manufacturing cost of the PCB  700  can be decreased but the foreign objects can be introduced in the spindle motor through the exposure unit  710 . 
         [0074]    In the exemplary embodiment of the present disclosure, in order to prevent the foreign objects from entering through the exposure unit  710  of the PCB  700  formed between the upper surface of the base plate  500  and the bottom surface of the core of the stator  200 , a foreign object inflow prevention fence  520  is formed at the base plate  500 . 
         [0075]    The foreign object inflow prevention fence  520  is formed along an edge of the semi-disk shaped lug  510  and takes a shape of curved fence. A distal end of the curvature-shaped foreign object inflow prevention fence  520  is brought into contact with a distal end of the PCB  700  formed by the exposure unit  710 , and the other distal end corresponding to the distal end of the foreign object inflow prevention fence  520  is brought into contact with the other distal end corresponding to the distal end of the PCB  700  formed by the exposure unit  710 . 
         [0076]    In the exemplary embodiment of the present disclosure, a height of the foreign object inflow prevention fence  520  may be substantially same as thickness of the PCB, for example. Alternatively, it should be apparent that the height of the foreign object inflow prevention fence  520  is greater than the thickness of the PCB. 
         [0077]    The foreign object inflow prevention fence  520  may be erected at a right angle relative to the base plate  500 . Alternatively, the foreign object inflow prevention fence  520  may be erected at an obtuse angle or an acute angle relative to the base plate  500 . 
         [0078]    In the exemplary embodiment of the present disclosure, the foreign object inflow prevention fence  520  may be formed by bending an edge of the semi-circular lug  510  of the base plate  500  to a direction facing the core  210 . In the exemplary embodiment of the present disclosure, the foreign object inflow prevention fence  520  formed by bending the edge of the semi-circular lug  510  of the base plate  500  is formed in the shape of a curved plate. 
         [0079]    Although a gap between the base plate  500  and the bottom surface of the core  210  of the stator  200  may increase by the PCB  700  formed with the exposure unit  710  for reducing the manufacturing cost, the foreign objects can be blocked by the foreign object inflow prevention fence  520  formed at the base plate  500  through the formation of the foreign object inflow prevention fence  520  formed at the base plate  500 . 
         [0080]    In the exemplary embodiment of the present disclosure, both distal ends of the foreign object inflow prevention fence  520  are brought into contact with the PCB  700 , whereby inflow of foreign objects are prevented from entering a space formed between the distal end of the foreign object inflow prevention fence  520  and the PCB  700 . 
         [0081]    Although the exemplary embodiments of the present disclosure have illustrated and explained a structure in which a part of the base plate  500  is bent to form the foreign object inflow prevention fence  520 , it should be apparent that the foreign object inflow prevention fence is alternatively formed by a synthetic resin material hardened along an upper edge of the lug  510  of the base plate  500  in a strip shape and coated on the base plate  500  using a dispenser. At this time, it should be apparent that the synthetic resin material has elasticity free from generating a static electricity, such that even if the synthetic resin material is brought into contact with the rotating yoke  410 , no noise and damage can be generated. 
         [0082]    Meanwhile, in order to prevent foreign objects such as dust introduced through the foreign object inflow prevention fence  520  from attaching to essential parts of the spindle motor despite the formation of the foreign object inflow prevention fence  520 , a foreign object attachment member may be arranged at a rear surface of the foreign object inflow prevention fence to which foreign objects introduced into the foreign object inflow prevention fence are attached. The foreign object attachment member may include an adhesive material having viscosity to which foreign objects having passed the foreign object inflow prevention fence  520  are attached. 
         [0083]    Meanwhile, the foreign object inflow prevention fence  520  preventing inflow of foreign objects may be manufactured with a synthetic resin material, and the foreign object inflow prevention fence  520  manufactured with the synthetic resin material may be attached to the base plate by an adhesive. 
         [0084]    As apparent from the foregoing, the spindle motor according to the exemplary embodiments of the present disclosure has an industrial applicability in that an exposure unit is formed at a part of a PCB interposed between a base plate and a core of a stator to reduce a manufacturing cost of the PCB, and foreign objects introduced through the exposure unit is prevented by a foreign object inflow prevention fence formed at the base plate to avoid the spindle motor from being polluted by the foreign objects. 
         [0085]    Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawing and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.