Abstract:
Transducers are oriented differently to address the skew phenomenon. This enables a greater area of the medium to be utilized for data storage, thereby increasing the storage capacity of the device implementing embodiments of the present invention.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to data storage, and more particularly to overcoming constraints resulting from skew angle phenomena.  
       BACKGROUND OF THE INVENTION  
       [0002]     In data storage systems where disc-shaped media are used, the media is generally rotated during operations. Data can thus be recorded in the form of one or more curved or circular tracks. Often, the transducers used for recording and retrieving data from the media are supported and moved in arcuate paths by an actuator which has an axis of rotation that does not coincide with the axis of rotation of the media. It follows that when the actuator is significantly skewed relative to the track tangent, the writer may overwrite to an adjacent track.  
         [0003]     It is not easy to overcome such skew angle phenomena. One known method involves spacing adjacent tracks sufficiently apart to avoid overwriting to adjacent tracks, but this means that the overall storage capacity of the media will be reduced. To compound the problem, the skew angle is different for different orientations of the actuator.  
         [0004]     The present invention therefore proposes a new approach to address this and other problems, thus offering advantages over the prior art.  
       SUMMARY OF THE INVENTION  
       [0005]     Embodiments of the present invention include providing at least two similar transducers oriented in different directions such that adverse effects of the skew phenomenon can be reduced. Optionally, the plurality of transducers are spaced apart on the same support so as to reach further parts of the medium without the need to increase the range of movement of the support. Overall, a greater area of the medium can be utilized for data storage, which means that the maximum amount of data that can be stored in a device can be increased.  
         [0006]     These and various other features as well as advantages which characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a schematic drawing of a data storage device employing a disc-shaped medium.  
         [0008]      FIG. 2  is a schematic view of a slider from the medium.  
         [0009]      FIG. 3 . is a schematic view of the slider according to some embodiments of the present invention.  
         [0010]      FIG. 4  is a schematic view of a slider according to alternative embodiments of the present invention.  
         [0011]      FIG. 5  is a flowchart according to other embodiments of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0012]     For ease of understanding and without intention to be limiting, embodiments of the present invention will be described with reference to a disc drive  100 , such as one schematically presented in  FIG. 1 .  
         [0013]     A medium  102  in this example is flat and annular, with an inner edge  104  and an outer edge  106  bounding at least one surface  108  which can be formatted for storing data. Data can generally be stored in one or more tracks  110 . Depending on the mechanism used, the tracks  110  may be a continuous spiral or a plurality of generally concentric circles. In any case, the curvature of the track  110  changes as one moves in a radial direction  112  across the medium  102 . For example, as one moves from the inner edge  104  to the outer edge  106 , one encounters decreasing track curvature, and vice versa.  
         [0014]     The medium  102  is mounted to a first motor  120 , operably coupled  122  to circuitry  124  so that it can be rotated  125  at desired speeds during operation. Also secured to the disc drive housing  126  is a second motor  128 , operably coupled  122  to circuitry  124 , for controllably driving an actuator  130 . The actuator  130  may include an arm  132  and a suspension assembly  134  supported at a distal end  136  of the arm  132 . The suspension assembly  134  may include a flexibly supported slider  200 , which in turn carries transducers (not shown) for recording data to the medium  102  or for retrieving data from the medium  102 . In this manner, transducers can be supported and moved to different tracks  110 , that is, to different radial locations of the medium  102 .  
         [0015]      FIG. 2  illustrates a schematic view of the slider  200  from the medium  102 . The slider  200  includes a body  202  with a surface  204  (referred to generally as the air bearing surface) that opposes the medium  102  when in use. When the disc drive  100  is in operation, the medium  102  and the slider  200  will be in relative motion to each other. For example, the second motor  128  may hold the actuator  130  somewhat stationary while the first motor  120  keeps the medium  102  in rotation. At such a time, a point on the track will first see the leading edge  206  of the slider followed by the air bearing surface  204 , and finally the trailing edge  208  of the slider.  
         [0016]     The slider  200 , and in particular the air bearing surface  204 , may be shaped to promote stability of the slider  200  in the resulting airflow. For example, the slider  200  may be shaped to be thicker at the two opposing sides  210  (referred to as side rails) which extend generally from the leading edge  206  to the trailing edge  208 . Some sliders  200  have one or more recessed areas  212  or protruding areas  214  generally at the center of the air bearing surface. In some cases, the trailing edge is at a chamfer  216 . Air bearing surface configurations come in great variety, and the examples mentioned here are solely for illustration and not intended to be limiting.  
         [0017]     The slider  200  is provided with at least two transducers  300  oriented in different directions  302 . Alternatively described, the transducers  300  are angularly displaced from one another, such that not all of the writers on the same slider face the same direction at any one time.  
         [0018]     In the example of  FIG. 3 , when the slider  200  is skew at an angle β relative to the direction of the track of interest (or track tangent)  302 , a first transducer  310  shows a smaller angular displacement of α 1  from the same track tangent  302 , and a second transducer  320  shows a larger angular displacement of α 2  from that track tangent  302 . The disc drive includes circuitry  330  configured to selectively operate the transducers  310 ,  320 . Here, the transducer having the smaller skew angle relative to the track tangent will be used for writing to that track, while the other transducer will be switched off or left out of operation. The result is that the disc drive operates with a smaller effective skew angle at this track.  
         [0019]     Previously, tracks near the edges  104 ,  106  of the medium  102  are not used because the skew angle β would have been very large, thus requiring wide spacing between adjacent tracks  110  to avoid overwriting and data corruption among other problems. However, by implementing an embodiment of the present invention, even the effective skew angles near the edges of the medium can be reduced. Thereby making it feasible to use these previously unusable areas. In this fashion, the overall data storage capacity of a medium, and accordingly of the entire data storage device, can be increased.  
         [0020]     Various embodiments may be implemented to suit the configuration of the data storage device. For example, the transducer support  400  of  FIG. 4  is provided with at least one transducer  410  that is aligned with the transducer support orientation  420  and at least one other transducer  430  that is fixed at an angular displacement  440  from the transducer support orientation  420 . Further, the appended drawings show the transducers positioned near the trailing edge because most sliders are configured such that their trailing edges will be closest to the medium. However, this does not exclude other possible locations for the transducers if so desired.  
         [0021]     The examples show the transducers in question to be configured for interacting with the same piece of medium  102  or contiguous recordable parts of a medium  102 . In some cases, the area or range of the medium  102  that may be affected by a first transducer (such as  310 ,  410 ) may overlap with that of a second transducer (such as  320 ,  430 ) which is oriented at a substantially non-zero angle (such as represented by α 1 -α 2  or  440 ) relative to the first transducer (such as  310 ,  410 ).  
         [0022]      FIG. 5  is a flowchart  500  of another embodiment of the present invention which provides a system capable of determining the writer that would have the smallest effective skew angle relative to the tangent of the track of interest, and selecting that writer for operation. As the actuator seeks out a track for the next operation  510 , the system makes the appropriate switch to the writer that will have the best skew angle value  520 .  
         [0023]     According to other embodiments of the present invention, the transducers  300  are spaced apart on the slider  200 . As shown in  FIG. 2 , at least one transducer  300  may be found at each of the side rails  210 . Thus, the transducers  300  can write to a bigger area without the need to increase the range of movement of the actuator  130 . This is particularly advantageous in systems where the slider  200  is likely to become unstable if it is too near the outer edge  106  of the medium  102 .  
         [0024]     It is to be understood that the foregoing disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, in some embodiments, a transducer may comprise separate apparatus for writing data to the medium (writers) and for reading data from the medium (readers). Alternatively, a transducer may comprise a single apparatus capable of both recording and retrieving data.