Abstract:
A data storage disk capable of limiting a crack from extending during operation is provided. The data storage disk has a center, an outer edge, an inner edge, and at least one slot. The slot is disposed between the outer edge and the inner edge. When a crack occurs in the disk, the slot disperses a stress which forces the crack to extend. Therefore, the slot hinders extension of the crack to prevent the disk from break.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to Taiwan Patent Application No. 091134056 entitled “Anti-Crack Data Storage Disk”, filed Nov. 22, 2002. 
     
    
     
       FIELD OF INVENTION  
         [0002]    The present invention generally relates to a data storage disk, and more particularly, to a data storage disk capable of limiting breakage caused by a crack during operation in a disk driver.  
         BACKGROUND OF THE INVENTION  
         [0003]    Recently, the revolution per minute (RPM) of a spindle motor in a disk driver has been continuously increased due to the increase of information-recording density of the data storage disk. However, problems regarding the high-speed spin of the data storage disk have been exposed, for example, the increase in breakage of the disk during operation, and most seriously, injuries caused by cracked disks flying out of the disk driver. Therefore, to design a disk capable of limiting breakage is the focus of development in the industry.  
           [0004]    [0004]FIG. 1 illustrates a conventional disk. It is known by those skilled in the art that when the disk spins at a high speed, the disk has a highest stress in the inner edge  103 . Therefore, a crack is generally generated on the inner edge and advances to the outer edge  101 .  
           [0005]    When the crack generated in the disk reaches the critical crack length, the advance of the crack increases substantially to make the disk break. It is also known that as the spin speed increases the critical crack length decreases.  
           [0006]    The commercial high-speed disk driver generally has a speed of 48x or 52x. According to David Nowell&#39;s experiments and theory, when the speed is 48x, the critical crack length is about 1.72 cm; when calculating by the destructive mechanics, the theoretical critical crack length becomes about 0.83 cm, which is about one half of the experimental value. When the speed is 52x, the experimental critical crack length is about 1.25 cm, and the theoretical critical crack length is about 0.6 cm, which is about one half of the experimental value. The factors of differences between experimental and theoretical values have been discussed in David Nowell&#39;s article and will not be elaborated herein.  
           [0007]    Therefore, there is a need to provide a disk suitable for operating at a high spin speed and capable of hindering a crack from advancing over the experimental critical crack length.  
         SUMMARY OF THE INVENTION  
         [0008]    It is one aspect of the present invention to provide a data storage disk capable of limiting breakage caused by a crack during operation in a disk driver.  
           [0009]    It is another aspect of the present invention to provide a data storage disk suitable for use in a high-speed disk driver.  
           [0010]    In an exemplary embodiment, the present invention provides a data storage disk having a gravity center, an outer edge, an inner edge, and at least one slot disposed between the outer edge and the inner edge. When a crack occurs in the data storage disk, the slot disperses a stress which forces the crack to extend. Therefore, the slot hinders an extension to the crack from extending to the outer edge so- as to keep the crack under the critical crack length and prevent breakage of the disk.  
           [0011]    The data storage disk further includes a data storage region for recording information. The data storage region is arranged between the outer edge and the inner edge, and the slot is disposed between the data storage region and the inner edge.  
           [0012]    In one embodiment, multiple slots are formed on the data storage disk. A geometry center of these slots coincides with the gravity center of the data storage disk. Furthermore, the slots is thus configured that a straight normal line drawn from the center toward any point at the outer edge intersects with at least one of the slots. Therefore, a crack generated on the inner edge is effectively hindered from advancing to the outer edge. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0014]    [0014]FIG. 1 illustrates a conventional data storage disk;  
         [0015]    [0015]FIG. 2A illustrates a data storage disk in a first embodiment of the present invention;  
         [0016]    [0016]FIG. 2B illustrates a data storage disk in a second embodiment of the present invention;  
         [0017]    [0017]FIG. 3A illustrates exemplary slots disposed between the data storage region and the inner edge;  
         [0018]    [0018]FIG. 3B illustrates exemplary slots disposed in the data storage region;  
         [0019]    [0019]FIG. 3C illustrates exemplary slots disposed between the data storage region and the outer edge;  
         [0020]    [0020]FIG. 4 illustrates a data storage disk in a third embodiment of the present invention;  
         [0021]    [0021]FIG. 5 illustrates a data storage disk in a fourth embodiment of the present invention; and  
         [0022]    [0022]FIG. 6 illustrates a data storage disk in a fifth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    The present invention provides a data storage disk  100 , which is capable of limiting breakage caused by a crack during operation in a disk driver. The data storage disk  100  can be any disk for storing information, such as video compact disk (VCD), digital-video-disk (DVD), mini disk, or the like.  
         [0024]    [0024]FIG. 2A illustrates an exemplary data storage disk  100  of the present invention. As shown in FIG. 2A, the data storage disk  100  has a center  400 , an outer edge  101 , an inner edge  103 , and at least one slot  200 . The slot  200  is disposed between the outer edge  101  and the inner edge  103 . In a preferred embodiment, the maximum distance “d” (not shown) between one of the slots  200  and the inner edge  103  is less than 1.25 cm.  
         [0025]    It is noted that though six slots  200  are shown in FIG. 2A, the number of slots  200  is not limited thereto. For example, four slots  200  are illustrated in FIG. 2B.  
         [0026]    As shown in FIG. 2A, the slot  200  defines an inner rim  201  of a smooth close loop. In other words, the inner rim  201  has no angled or sharp point so as to prevent stress from concentrating on the point where a crack might be induced when a force is exerted on the data storage disk  100 .  
         [0027]    When a crack occurs in the data storage disk  100 , it generally advances toward the outer edge  101 . When the crack advances to the slot  200 , the stress of forcing the crack to advance is dispersed to the inner rim  201  of the slot  200 . In other words, the slot  200  effectively hinders further extension of the crack and keeps the crack under the critical crack length so as to prevent breakage of the disk  100 .  
         [0028]    When the data storage disk  100  is operated, the crack is generally generated on the inner edge  103  and advances toward the outer edge  101  because the stress is higher around the inner edge  103 . In a preferred embodiment, the maximum distance “d” between one of the slots  200  and the inner edge  103  is less than 1.25 cm to ensure that the crack remains under the critical crack length when spinning under a high speed, such as 52x.  
         [0029]    As shown in FIG. 3A, the data storage disk  100  further includes a data storage region  303  for storing data. The data storage region  303  is arranged between the outer edge  101  and the inner edge  103 . In this embodiment, the slot  200  is disposed between the data storage region  303  and the inner edge  103 . In other embodiments, the slot  200  can be disposed within the data storage region  302  or between the data storage region  303  and the outer edge  101 , as shown in FIGS. 3B and 3C, respectively.  
         [0030]    As shown in FIG. 3A, the exemplary data storage disk also includes a center hollow portion  301  and a non-recording portion  305 . The center hollow portion  301  surrounded by the inner edge  103  is a hole around the center  400  of the disk. The data storage disk  100  engages with the disk driver by a spindle passing through the center hollow portion  301 . In this embodiment, the center hollow portion  301  is a hole in a round shape; however, the center hollow portion can be in other shapes such as square, oval, or the like, and is not limited thereto.  
         [0031]    The non-recording portion  305  is disposed between the center hollow portion  301  and the data storage region  303 . The disk driver holds the non-recording portion  305  so as to provide a driving force for spinning the data storage disk  100 . The slot can be disposed in the non-recording portion  305  and hinder the crack from advancing to the outer edge  101  so as to prevent the breakage of the data storage disk  100 .  
         [0032]    As shown from FIG. 2A to FIG. 3B, the slot is in a curved shape. Multiple slots  200  are disposed circumferentially around the center  400  of the data storage disk  100 . In such arrangement, the slots  200  are arranged around the center  400  in a configuration similar to the rotation direction of the data storage disk  100 . However, in other embodiments, the slots  200  can be in a different shape, for example, in bar shape as shown in FIG. 4.  
         [0033]    As shown from FIG. 2A to FIG. 3B, the data storage disk  100  has a center  400 , and the center  400  can be the center of mass, center of rotation, center of geometry, or other physically or geometrically defined center. The slots  200  are in a curved shape, and the center of the slots  200  is coincided with the center  400  of the data storage disk  100  as shown from FIG. 2A to FIG. 4.  
         [0034]    In addition, the slots  200  can be asymmetrically disposed around the center  400  as shown in FIGS. 5 and 6. It is noted that the center of geometry of slots  200  is not required to coincide with the center  400  of the data storage disk  100 . As shown in FIG. 6, the center of geometry of slots  200  does not coincide with the center  400  of the data storage disk  100 . By adjusting the center of gravity of the data storage disk  100 , it still can maintain the balance when spinning at a high speed.  
         [0035]    As shown from FIG. 2A to FIG. 3B, a straight normal line drawn from the center  400  or any point at the inner edge  103  toward any point at the outer edge  101  intersects with at least one of the slots  200 . In such arrangement, the slots  200  can effectively hinder most cracks generated on the inner edge  103  from advancing to the outer edge  101 .  
         [0036]    Although specific embodiments have been illustrated and described, it will be obvious to those skilled in the art that various modifications may be made without departing from what is intended to be limited solely by the appened claims.