Patent Publication Number: US-2007101348-A1

Title: Shaft adjusting device for optical pickup unit

Description:
This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 094137813 filed in Taiwan, Republic of China on Oct. 28, 2005, the entire contents of which are thereby incorporated by reference.  
     FIELD OF THE INVENTION  
      The present invention relates to a shaft adjusting device for an optical pickup unit, and more particularly to a shaft adjusting device of which assembly is simple and production cost is decreased.  
     DESCRIPTION OF RELATED ART  
      Please refer to  FIGS. 1 and 2 .  FIG. 1  is an exploded view showing a conventional shaft adjusting device for an optical pickup unit, and  FIG. 2  is a partly enlarged view showing the conventional shaft adjusting device shown in  FIG. 1 .  
      As  FIG. 1  shows, an optical pickup transmission structure of a conventional optical disc drive mainly comprises an optical pickup module  1  used for reading data on an optical disc, a driving motor set (not shown in the figure) for driving the optical pickup module  1 , a pair of shafts  11 ,  11  used for mounting and guiding the optical pickup module  1 , and a loader  20  used for mounting a spindle motor  21  and the shafts  11 ,  11 . The operation of the transmission structure is as follows: the driving motor set installed at one side of the loader  20  drives the optical pickup module  1  to move it along the shafts  11 ,  11  to and fro so as to read data stored on the optical disc.  
      In the optical disc drive, the laser beam emitted from the optical pickup module  1  is more perpendicular to the surface of the optical disc, the reading accuracy is better. As the optical pickup module  1  is mounted on the shafts  11 ,  11 , after the drive is assembled, the height of the end portion of the shaft  11  is adjusted by a shaft adjusting device to make sure that the laser beam emitted from the optical pickup module  1  is perpendicular to the surface of the optical disc.  
      The conventional shaft adjusting device, as  FIG. 2  shows, is installed on the loader  20  adjacent to the end of the shaft  11 . The structure of the conventional shaft adjusting device mainly comprises a leaf spring  22  and a screw  23 . One end of the leaf spring  22  is fixed on the loader  20  and another end thereof is a free end used for supporting the end of the shaft  11 . The screw  23  is fixed on the loader  20  and used for locking the shaft  11  on the loader  20  so that the end of the shaft  11  is clamped between the screw  23  and the leaf spring  22 . The height of the end of the shaft is adjusted by screwing the screw  23  up or down.  
      However, the leaf spring  22  is easily over-pressed by screwing the screw  23  into the loader  20  too much. The elastic fatigue of the leaf spring  22  will happen, and the leaf spring  22  will lose its function to clamp the end of the shaft  11  with the screw  23 . Relatively, the reading accuracy of the optical disc drive is bad.  
      In order to solve the elastic fatigue problem of leaf spring, the leaf spring  22  is replaced with a coil spring. Please refer to  FIG. 3 .  FIG. 3  is a partly exploded view showing a conventional shaft adjusting device using a coil spring.  
      The end of the shaft  11  is clamped by a coil spring  30  and the screw  23 . In order to fix the coil spring  30  on the loader  20 , an additional mounting element  201  is installed on the loader  20 . The mounting element  201  has a through hole  202 , and the coil spring  30  is placed in the through hole  202 . According to the conventional shaft adjusting device using the coil spring, the component number increases and the assembly cost and time increase too.  
      Therefore, how to fix a spring stably on a loader without increasing the number of components and the assembly costs is a topic on which the present invention makes an effort.  
     SUMMARY OF THE INVENTION  
      One object of the present invention is to provide a shaft adjusting device for an optical pickup unit, which can effectively adjust the hieght of the end of the shaft through a simple structure, and number of elements is reduced owing to the simple structure so that the costs and the time for manufacturing and assembly can be lowered down.  
      For attaining the object mentioned above, the present invention proposes a shaft adjusting device for an optical pickup unit, which is installed on a loader of an optical disc drive and near the end of a shaft, and comprises a spring, a first locking element, and a second locking element. The spring is fixed on the loader for supporting the end of the shaft and has a first hook portion extendedly formed from one end thereof. The first locking element is disposed on the loader and clamps the end of the shaft with the spring. The second locking element passes through the first hook portion and is locked into the loader for fixing the spring on the loader.  
      According to the preferred embodiment of the present invention, it can further comprise an auxiliary positioning structure. The auxiliary positioning structure is a raised block disposed on the loader and near the end of the shaft, the outer diameter of the block is matched with the inner diameter of the spring, and the spring is put around the raised block so as to fix the spring on the loader more stably.  
      As mentioned above, the auxiliary positioning structure can be a second hook portion formed extendedly from the end of the first hook portion and is hooked in the first locking element to further position the spring on the loader more stably.  
      According to the preferred embodiment of the present invention, a sleeve for receiving the first locking element in and out is further disposed on the loader, and the second hook portion also can be hooked in the sleeve.  
      According to the preferred embodiment of the present invention, when the first locking element is locked into the loader and presses the shaft, the shaft in turn presses the spring to deform the spring and lower the end of the shaft. When the first locking element is screwed out of the loader, the end of the shaft is ascended through the elastic force of the spring. Therefore, the height of the end of the shaft is controlled by the locked depth of the first locking element in the loader, and furthermore, the laser beam emitted from the optical pickup unit can be normal to the surface of the optical disc to ensure the best reading quality of the optical pickup unit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention can be more fully understood by reference to the following description and accompanying drawings, in which:  
       FIG. 1  is an exploded view showing a conventional shaft adjusting device for an optical pickup unit;  
       FIG. 2  is a partly enlarged perspective view showing the conventional shaft adjusting device shown in  FIG. 1 ;  
       FIG. 3  is a partly enlarged exploded view showing another conventional shaft adjusting device for an optical pickup unit;  
       FIG. 4  is an exploded view showing a shaft adjusting device for an optical pickup unit according to a first preferred embodiment of the present invention;  
       FIG. 5  is a partly enlarged exploded view showing the shaft adjusting device of  FIG. 4 ;  
       FIG. 6  is a partly enlarged perspective view showing the shaft adjusting device of  FIG. 4 ;  
       FIG. 7  is a partly enlarged exploded view showing a shaft adjusting device for an optical pickup unit according to a second preferred embodiment of the present invention; and  
       FIG. 8  is a partly enlarged exploded view showing a shaft adjusting device for an optical pickup unit according to a third preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Please refer to  FIGS. 4, 5  and  6 .  FIG. 4  is an exploded view showing a shaft adjusting device for an optical pickup unit according to a first preferred embodiment of the present invention.  FIG. 5  is a partly enlarged exploded view showing the shaft adjusting device of  FIG. 4 .  FIG. 6  is a partly enlarged perspective view showing the shaft adjusting device of  FIG. 4 .  
      As  FIGS. 4, 5  and  6  show, the present invention provides a shaft adjusting device for an optical pickup unit, in which a spindle motor  41  and an optical pickup module  42  are installed on a loader  40 . Two shafts  43  are respectively installed at two sides of the optical pickup module  42 . The optical pickup module  42  is mounted and moved on the shafts  43  and slid on the loader  40  to read the data on an optical disc. Moreover, a pair of ribs  401  is protruded on the loader  40  at a position near at least one end of the shaft  43  and integrated formed with the loader  40 . The end of shaft  43  is placed between and restrained by the ribs  401 . The shaft adjusting device of the first preferred embodiment of the present invention is installed on the loader  40  at a position near at least one end of the shaft  43 . Alternatively, the shaft adjusting devices can be installed on the loader  40  in one or more places near one or two ends of each shaft  43 . The shaft adjusting device is used for adjusting the height of the end of shafts  43  relative to the loader  40  to allow a laser beam emitted from the optical pickup module  42  to be perpendicular to the surface of the disc.  
      The shaft adjusting device comprises a first locking element  50 , a spring  60 , and a second locking element  70 , in which the first locking element  50  is fixed on the loader  40  and used for pressing the end of the shaft  43 , and a sleeve  402  for receiving the first locking element  50  in or out is provided on the loader  40 . The sleeve  402  is integrated formed with the loader  40 .  
      The spring  60  is installed on the loader  40  near one end of the shaft  43 . The spring  60  is placed under the end of the shaft  43  (as  FIG. 6  shows) and clamps the end of the shaft  43  with the first locking element  50 . One end of the spring  60  is further extendedly formed with a first hook portion  61 ; and the second locking element  70  is disposed on the loader  40  and passes through the first hook portion  61  so as to fix the spring  60  on the loader  40 . When the first locking element  50  is locked into the loader  40 , the end of the shaft  43  is pressed by the first locking element  50  to press the spring  60  and lower its height. Moreover, when the first locking element  50  is screwed out of the loader  40 , the elastic force of the spring  60  props up against the end of shaft  43  and lifts the end of shaft  43 , and the height of the end of shaft  43  is, therefore, increased.  
      Please refer again to  FIGS. 5 and 6 , according to the first preferred embodiment of the present invention, when assembling the shaft  43  on the loader  40 , the spring  60  is first placed on the loader  40  at a position near the end of the shaft  43 . Thereafter, the second locking element  70  is passed through the first hook portion  61  of the spring  60  to fix the spring  60  on the loader  40 . Then, the end of the shaft  43  is placed between ribs  401  and on the spring  60 . Finally, the first locking element  50  is locked into the sleeve  402  and clamps the end of the shaft  43  with the spring  60 .  
      After assembling, when the first locking element  50  is further locked into the sleeve  402 , it can press the shaft  43  down to deform the spring  60 , and the height of the end of shaft  13  is decreased. Alternatively, when the first locking element  50  is screwed out from the sleeve  402 , the spring  60  props up against the shaft  43  and increases the height of the end of shaft  43 . Whereby, the effect for adjusting the height of the end of the shaft  43  can be attained. Therefore, by means of the first hook portion  61  formed extendedly from the spring  60 , the present invention can effectively attain the purpose for fixing the spring  60  without additional components.  
      Please refer to  FIG. 7 .  FIG. 7  is a partly enlarged exploded view showing the shaft adjusting device for an optical pickup unit according to a second preferred embodiment of the present invention.  
      As the figure shows, the structure of shaft adjusting device is similar to which shown in  FIG. 5 . The different is that the shaft adjusting device in this embodiment further comprises an auxiliary positioning structure. The auxiliary positioning structure is a second hook portion  62  further formed extendedly from the end of the first hook portion  61 . The second hook portion  62  is hooked with the first locking element  50  or the sleeve  402  for fixing the spring  60  on the loader  40  more stably and preventing the spring  60  from being slid on the loader  40  under an uneven force pressed by the shaft  43 .  
      Finally, please refer to  FIG. 8 .  FIG. 8  is a partly enlarged exploded view, showing a shaft adjusting device for an optical pickup unit according to a third preferred embodiment of the present invention.  
      As the figure shows, the structure of shaft adjusting device is similar to which shown in  FIG. 5 . The different is that the shaft adjusting device in this embodiment further comprises an auxiliary positioning structure. The auxiliary positioning structure in this embodiment is a raised block  403 . The raised block  403  is integrated formed on the loader  40  near the end of the shaft  43 ; the outer diameter of the raised block  403  is matched with the inner diameter of the spring  60 . The spring  60  is put around the raised block  403  to prevent the spring  60  from being slid on the loader  40  under the uneven force pressed by the shaft  43 .  
      Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.