Abstract:
An optical pickup transferring apparatus including a slider having a base, a floating portion elastically coupled to the base, the floating portion having on one side thereof at least one protuberance inserted into the external thread of a lead screw, and an elastic element located on the top of the base and the floating portion. The elastic element includes a first elastic portion to push the floating portion toward the lead screw so that the protuberance is inserted into the external thread, and a second elastic portion to push the floating portion toward the screw groove to thereby prevent the protuberance from escaping from the external thread when the floating portion is transformed elastically.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims the priority of Korean Patent Application No. 2003-28598, filed on May 6, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an optical pickup transferring apparatus and, more particularly, to an optical pickup transferring apparatus of an optical disk drive with an improved slider which supports an optical pickup.  
           [0004]    2. Description of the Related Art  
           [0005]    Generally, an optical disk drive to write information on and read information from an optical disk such as a compact disk (CD) and a digital versatile disk (DVD) includes a sub-chassis assembly which has an optical pickup to emit a beam onto the optical disk and then to collect light reflected therefrom in order to write or read information.  
           [0006]    [0006]FIG. 1 is a plan view of an example of a conventional sub-chassis assembly of an optical disk drive. FIG. 2 is a perspective view of the slider of a conventional sub-chassis assembly shown in FIG. 1.  
           [0007]    Referring to FIG. 1, a sub-chassis assembly  100  comprises a sub-chassis  101 , a turntable  110  to accommodate an optical disk  103  which is rotated by a spindle motor (not shown), an optical pickup  120  to write and read information on and from the optical disk  103 , and an optical pickup transferring apparatus to rectilinearly shift the optical pickup  120  in a radial direction of the optical disk  103 .  
           [0008]    The optical pickup transferring apparatus comprises a pair of guide rails  141  and  142  to allow the optical pickup  120  to move rectilinearly in a radial direction of the optical disk  103 , a lead screw  151  installed in parallel with the guide rails  141  and  142  and having an external thread  152 , a driving motor  150  to rotate the lead screw  151 , and a slider  160  mounted on the lead screw  151  and performing motion along the lead screw  151  in accordance with the rotation of the lead screw  151  in order to rectilinearly move the optical pickup  120  in a radial direction of the radius of the optical disk  103 .  
           [0009]    The slider  160  comprises a base  161 , a support  163 , a floating portion  165 , and a spring  169 , as shown in FIG. 2.  
           [0010]    The base  161  is connected to the optical pickup  120 . The floating portion  165 , coupled to the support  163 , has two protuberances  167  inserted into the external thread  152  of the lead screw  151 . The support  163  is integrally coupled with the floating portion  165  which thereby supportably approaches or departs from the base  161 . The spring  169  is installed between the support  163  and the floating portion  165  so as to elastically bias the floating portion  165  toward the lead screw  151  with respect to the base  161 .  
           [0011]    When the lead screw  151  is rotated by the driving motor  150 , the slider  160  rectilinearly shifts the optical pickup  120  in a radial direction of the radius of the optical disk  103  by the protuberances  167  inserted into the external thread  152  of the lead screw  151 .  
           [0012]    In the conventional optical pickup transferring apparatus constructed as above, if the driving motor  150  is rotated abruptly, the floating portion  165  is drifted suddenly toward the base  161  so that the protuberances  167  may escape from the external thread  152  of the lead screw  151 . This effect mainly happens when the distance between the external thread  152  and the protuberances  167  becomes wider over time because of wear. Such a result may be further aggravated when the elasticity of the spring  169  weakens.  
           [0013]    When the protuberances  167  of the slider  160  escape from the external thread  152 , the slider  160  slips on the lead screw  151 , which causes difficulty in configuring the firmware contained in the optical disk drive to accurately control the position and intensity of a laser beam to write and read information on and from the optical disk  103 . If the strength of the spring  169  is reinforced, the protuberances  167  may be prevented from escaping from the external thread  152 . However, this increases the friction between the external thread  152  and the protuberances  167  thereby causing the lead screw  151  to not rotate smoothly.  
           [0014]    In addition to the fact that the optical pickup  120  is difficult to accurately control, the spring  169  simply pushes the floating portion  165  toward the lead screw  151  and thereby causes the protuberances  167  to be inserted into the external thread  151 . Therefore, accounting of the contact load between the protuberances  167  and the external thread  152  during the servo control of the optical disk drive is difficult.  
         SUMMARY OF THE INVENTION  
         [0015]    The present invention provides an optical pickup transferring apparatus with an improved structure in which a contact force between a slider and a lead screw is doubly controlled to thereby reduce a contact load, and to prevent the slider from separating from the lead screw, to efficiently control the motion of the optical pickup.  
           [0016]    According to an aspect of the present invention, an optical pickup transfer apparatus comprises a lead screw having an external thread, and a slider, coupled with the optical pickup, to rectilinearly move the optical pickup in a radial direction of the optical disk in accordance with a rotation of the lead screw, wherein the slider includes a base, a floating portion elastically coupled to the base, having on one side thereof at least one protuberance inserted into the external thread of the lead screw, and an elastic element located on top of the base and the floating portion.  
           [0017]    According to another aspect of the present invention, the elastic element comprises a first elastic portion to push the floating portion toward the lead screw so that the protuberance is inserted into the external thread; and a second elastic portion to push the floating portion toward the external thread to thereby prevent the protuberance from escaping from the external thread when the floating portion is transformed elastically.  
           [0018]    Additional and/or other aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
         [0020]    [0020]FIG. 1 is a plan view of one example of a conventional sub-chassis assembly;  
         [0021]    [0021]FIG. 2 is a perspective view of the slider of the conventional sub-chassis assembly shown in FIG. 1;  
         [0022]    [0022]FIG. 3 is a plan view of one embodiment of a sub-chassis assembly having an optical pickup transferring apparatus according to an embodiment of the present invention;  
         [0023]    [0023]FIG. 4 is a perspective view of the slider shown in FIG. 3;  
         [0024]    [0024]FIG. 5 is a rear view of the slider shown in FIG. 3;  
         [0025]    [0025]FIG. 6 is a front view of the slider shown in FIG. 3; and  
         [0026]    [0026]FIG. 7 is an enlarged perspective view of the elastic element of the slider shown in FIG. 4. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.  
         [0028]    Referring to FIG. 3, a sub-chassis assembly according to an embodiment of the present invention comprises a sub-chassis  201 , a spindle motor  210  to rotate an optical disk D, that is, an optical recording medium, an optical pickup  220  to emit light onto the optical disk D while rectilinearly shifting in a radial direction of the optical disk D, and to receive the light reflected therefrom in order to write and/or read information, and an optical pickup transferring apparatus to allow the optical pickup  220  to slide in the radial direction of the optical disk D.  
         [0029]    The optical pickup transferring apparatus comprises a pair of guide rails  241  and  242  to allow the optical pickup  220  to rectilinearly move in the radial direction of the optical disk D, a lead screw  251  installed in parallel with the guide rails  241  and  242  and having an external thread  252 , a driving motor  250  to rotate the lead screw  251 , and a slider  260  to convert the rotation of the lead screw into rectilinear motion and to rectilinearly shift the optical pickup  220  in the radial direction of the optical disk D.  
         [0030]    The slider  260  comprises a base  261 , a floating portion  263 , and an elastic element  267 , as shown in FIGS. 4 through 7.  
         [0031]    The base  261  is mounted on the optical pickup  220  and is fastened by a coupling element (not shown), through a plurality of piercing holes  262  formed through a side of the slider. In various embodiments of the invention, other fastening elements may be employed in mounting the base  261 .  
         [0032]    The floating portion  263  protrudes from one side of the base  261  and is elastically formed with a plurality of protuberances  264  provided aslant at a predetermined angle with one side  263   a  facing the lead screw  251 . The protuberances  264  are inserted into the external thread  252  of the lead screw  251 , and shift the optical pickup  220  in the radial direction of the disk D while sliding along the external thread  252  when the lead screw  251  is rotated.  
         [0033]    On the top surface  263   c  of the floating portion  263 , a slot  265  is formed where the elastic element  267  is positioned. On the other side  263   b  of the floating portion, i.e., the side facing the base  261  and opposite to the one side  263   a  where the protuberances  264  are formed, a bump  266  is protruded toward the base  261 . The operation of the bump  266  will be explained later.  
         [0034]    The elastic element  267  is located on the base  261  and the floating portion  263  and is fixed onto the base  261  by a fastening element (not shown) through a plurality of holes  267   a  formed on one side. The other side of the elastic element  267  has first and second elastic portions  268  and  269  on the top surface  263   c  of the floating portion at a predetermined interval. The elastic element  267  may be fixed to the base  261  in a variety of ways according to various embodiments of the invention. In this embodiment of the invention, the fastening element (not shown) includes holes  262  and  267   a  provided respectively in the base  261  and the elastic element  267 .  
         [0035]    The first elastic portion  268  is formed in the shape of a plate spring. The end of the first elastic portion  268  is bent to penetrate the slot  265  and then to make contact with the side  263   b  of the floating portion  263 , which is opposite to the side from which the protuberances  264  protrude. The first elastic portion  268  has an elasticity which is sufficient to push the floating portion  263  toward the lead screw  251  and to thereby allow the protuberances  264  to be inserted into the external thread  252  of the lead screw  251 .  
         [0036]    The second elastic portion  269  is plate-spring shaped and therefore similar to the first elastic portion  268 . The end of the second elastic portion  269  is also bent to penetrate the slot  265  and then to be spaced at a predetermined distance by the bump  266 .  
         [0037]    The second elastic portion  269  is wider than the first elastic portion  268  in order to enlarge the elasticity coefficient k of the second elastic portion  269  as compared to than that of the first elastic portion  268 .  
         [0038]    The distance between the second elastic portion  269  and the bump  266  prevents the floating portion  263  from receiving an excessive restraining force from the first and second elastic portions  268  and  269  when the first and second elastic portions  268  and  269  substantially simultaneously make contact with the floating portion  263 . As a result, the first and second elastic portions  268  and  269  do not deteriorate or otherwise suffer damage over the lifetime of the apparatus. This arrangement facilitates the guiding of the optical pickup  220  (with reference to FIG. 3) in the direction of the radius of the disk D. The detachment of the protuberances  264  from the external thread  252  may be prevented by the second elastic portion  269  making contact with the bump  266  to hinder the floating portion  263  from being elastically deformed toward the base  261 .  
         [0039]    In this case, the distance between the second elastic portion  269  and the bump  266  is shorter than the depth the protuberances  264  are inserted into the external thread  252 . This prevents the protuberances  264  from being detached from the external thread  252  as the bump  266  comes into contact with the second elastic portion  269 .  
         [0040]    The locations of the first and second elastic portions  268  and  269  are not confined to the embodiment depicted in FIGS. 4 through 7 but may have inverted positions.  
         [0041]    Hereinafter, the operation of the optical pickup transferring apparatus according an embodiment of to the present invention will be described with reference to the attached drawings.  
         [0042]    As shown in FIG. 3, after the slider  260  is installed in the optical pickup  220  with the protuberances  264  inserted into the external thread  252 , the optical pickup  220  is moved in a radial direction of the disk D when the lead screw  251  is rotated by the this situation driving motor  250 . In this situation, the first elastic portion  268  makes contact with the side  263   a  of the floating portion  263 , which is opposite to the side from which the protrusions  264  protrude, to push the floating portion toward the lead screw  251  and thereby insert the protuberances  264  into the external thread  252 .  
         [0043]    When the protuberances  264  tend to escape from the external thread  252  due to an external force, the floating portion  263  is elastically deformed to drift toward the base  261 . Accordingly, the floating portion  263  is prevented from drifting by the elastic nature of the second elastic portion  269  that makes contact with the bump  266 .  
         [0044]    As is described above, the optical pickup transferring apparatus of the present invention facilitates the control of the optical pickup by doubly controlling the contact force between the lead screw and the slider, as well as the prevention of the optical pickup from departing from the lead screw.  
         [0045]    Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.