Abstract:
A head actuator supporting a data head for read or write operations. The actuator includes a head support excitation shield along a flow path to a leading edge of the slider (or head) to isolate the head support from flow induced excitation and vibration. A method for reading or writing data on a disc via a data head supported by a head support including rotating the disc to create an airflow stream and diverting the air flow stream to shield the head support from excitation.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    The present application claims priority to U.S. Provisional Application Ser. No. 60/126,345, filed Mar. 26, 1999 and entitled “PIVOT HOUSING MODIFICATION TO ADDRESS FLOW INDUCED VIBRATION OF THE HEAD GIMBAL ASSEMBLY”. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to a data storage system. In particular, the present invention relates to a head support shield for shielding the head support from excitation and vibration to, inter alia, limit off-track errors.  
         BACKGROUND OF THE INVENTION  
         [0003]    Disc drives are used to store digitally encoded information on discs. Data heads read data from or write data to data tracks of a disc supported for rotation by a spindle motor or drive. Data heads are supported by a head actuator and include transducer elements for reading data from or writing data to a disc. Typically, data heads “fly” above the disc surface for read and write operations. The transducer elements are supported on a slider of the data head and rotation of the discs creates an air flow under an air bearing surface of the slider to lift the slider above the disc surface for read or write operations. Near contact and contact recording are also known.  
           [0004]    The head actuator includes a rigid actuator arm supporting a flexible suspension assembly. Data heads are supported at an extended end of the suspension assembly. The head actuator is rotated or actuated by a voice coil motor to position data heads relative to selected data tracks for read or write operations. During operation, the spindle drive rotates the disc creating an air flow path along the rigid actuator arm and flexible suspension to the air bearing of the slider. Spindle rotation speed of disc drives is increasing to provide faster seek times. Increased spindle rotation increases disc air flow along the rigid actuator arm and flexible suspension to the air bearing. Increased air flow can create more air turbulence causing excitation or vibration of the head support. Depending upon the nature and frequency of the excitation force, excitation or vibration can induce torsional mode resonance, sway mode resonance or bending mode resonance. Vibration or resonance of the head support can induce off-track movement of the data heads. Disc drive data density (or tracks per inch) is increasing and thus drive performance is more sensitive to off-track errors. The present invention addresses these and other problems, and offers other advantages over prior art.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention relates to a head actuator assembly including a head support excitation shield along the flow path to a leading edge of the head for protecting the head support from flow induced vibration and excitation. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a perspective illustration of a rotary disc drive.  
         [0007]    [0007]FIG. 2 is a perspective illustration of a head actuator supporting data heads.  
         [0008]    [0008]FIG. 3 is a detailed illustration of data heads coupled to a suspension assembly.  
         [0009]    [0009]FIG. 4 is a detailed illustration of a prior art head actuator including a head support aligned along an air flow path to a leading edge of a data head.  
         [0010]    [0010]FIG. 5 is a cross-sectional view taken along line  5 - 5  of FIG. 1.  
         [0011]    [0011]FIG. 6 is a velocity profile of an air flow stream for a prior art head actuator.  
         [0012]    [0012]FIG. 7 is a detailed illustration of an embodiment of a head actuator of the present invention including a head support excitation shield along a flow path to a leading edge of the data head.  
         [0013]    [0013]FIG. 8 is a velocity profile of an air flow stream for the head actuator illustrated in FIG. 7.  
         [0014]    [0014]FIG. 9 is a flow chart for a method of operation for reading or writing data to a disc. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    [0015]FIG. 1. illustrates a rotary disc drive  50  including a disc chassis  52 , discs  54  and a head actuator  56 . Discs  54  are rotationally coupled to chassis  52  via a disc spindle drive  57  (illustrated diagrammatically) for rotation, as illustrated by arrow  58 . Discs store data on concentric data tracks. The head actuator  56  supports data heads  60  relative to a disc surface and in FIG. 1 is rotated to move heads  60  along an arcuate path as illustrated by arrow  62  to position heads  60  relative to selected data tracks for read or write operations via operation of voice coil motor (VCM)  64 .  
         [0016]    [0016]FIG. 2 is a perspective illustration of an embodiment of a head actuator  56  supporting heads  60 . As shown in FIG. 2, head actuator  56  includes a voice coil  66 , a bearing channel  68  and a plurality of stacked head supports  70 . Voice coil  66  is supported for operation in a backiron assembly  72  (illustrated in FIG. 1) to form the VCM  64  for moving head actuator  56  along path  62 . A bearing cartridge  74  is supported in bearing channel  68  to rotationally connect head actuator  56  to chassis  52 . Heads  60  are supported by head supports  70  relative to surfaces of discs in a disc stack for read or write operations.  
         [0017]    In the embodiment shown, head supports  70  include a flexible suspension assembly  76  connected to and supported by a rigid actuator arm  78 . The suspension assembly  76  includes an elongated flexible load member  80  and a gimbal spring  82 , as shown in FIG. 3. Heads  60  include a slider  84  having leading and trailing edges  86 ,  88  and opposed side edges  90 ,  92 . Slider supports transducer elements  93  (shown diagrammatically) at the trailing edge  88 . Transducer elements  93  may be inductive, magnetorestive or magneto-optical transducer elements. Slider  84  is coupled to suspension assembly  76  via gimbal spring  82  and is supported so that the leading edge  86  of the slider  84  (or data head  60 ) faces the head support  70  and opposed side edges  90 ,  92  extend in longitudinal alignment with the head support  70  or suspension assembly  76 . Gimbal spring  82  supports the slider  84  or head to pitch and roll relative to the disc surface to follow the topography of the disc surface.  
         [0018]    For operation, discs  54  are rotated by spindle drive  57  which, as shown in FIG. 4, creates an air flow stream as illustrated by arrows  94  along the head support  70  to the leading edge  86  of the slider  84  (head  60 ) for proximity or near proximity recording. Interference of the head support  70  with the air flow stream can create turbulence. For example, as shown in FIG. 5, the thickness and height of the actuator arm  78  restricts air flow over the disc surface because of the limited spacing  94  between the actuator arm  78  and disc surface  54 . The restricted air flow can create a turbulent flow stream as illustrated in the flow velocity profile shown in FIG. 6 which can excite or vibrate the head support  70 .  
         [0019]    As shown in FIG. 6, constricted air flow along head support  70  (actuator arm  78 ) produces a turbulent air flow region  100  proximate to an extended tip  104  of the actuator arm  78 . As illustrated in FIG. 4, a base of suspension assembly  76  is mounted to the tip  104  of the actuator arm  78  proximate to the turbulent flow region  100 . The turbulent flow region  100  can interfere or excite motion of the suspension assembly  76 . The suspension assembly  76  illustrated in FIG. 4 includes a plurality of struts  106 ,  108  at the base of the suspension assembly which are particularly sensitive to vibration and excitation. Excitation or vibration of the head support  70  can induce off-track movement of the data heads  60  and can excite torsional, bending or sway mode resonance. Vibration or excitation of the head support  70  can induce head-disc contact due to bending or in-plane movement of the head  60 . The present invention relates to a head support shield to divert turbulent air flow and limit vibration or excitation of the head support  70 .  
         [0020]    FIGS.  7 - 8  illustrate an embodiment of a head support excitation shield  110  of the present invention. The excitation shield  110  illustrated in FIGS.  7 - 8  alters the restricted air flow to shift turbulent flow region  100 - 1  away from the head support  70  to limit excitation or vibration of the head support  70 . In the embodiment shown, shield includes an air flow extension or finger  112  on the tip  104  of the actuator arm  78  to divert or shift the turbulent flow region  100  from the base of the suspension assembly  76 .  
         [0021]    As shown in FIG. 7, finger  112  extends from a windward edge (facing the air flow stream) of tip  104 . finger  112  protrudes beyond sides of the actuator arm  78  and suspension assembly  76  to form a channel boundary for the turbulent air flow stream spaced from the head support  70 . The spaced turbulent air flow boundary protects the head support  70  from excitation and vibration. FIG. 7 illustrates a simulated velocity profile of air flow along actuator arm  78  and finger  112 . As shown, the turbulent air flow stream  100 - 1  is shifted away from the base of the suspension assembly  76  to reduce excitation of the assembly.  
         [0022]    As illustrated in FIGS.  7 - 8 , finger  112  includes a flat end face  116  and a sloped edge face  118 . The sloped edge  118  angles away from tip  104  of actuator arm  78  in the direction of the air flow stream to direct turbulent air flow away from the head support  70 . The thickness -t- of finger  112  is similar to the thickness -t- of the actuator arm  78  illustrated in FIG. 5. Finger  112  can be constructed of aluminum and formed with the actuator arm  78 . Finger  112  can be separately formed, for example, on a mounting plate of the suspension assembly and swaged to the tip of the actuator arm  78 . Preferably, the finger  112  includes a smooth outer windward edge (edge  118 ) to limit friction at the boundary walls along the flow channel to provide smooth air flow therealong. In FIGS.  7 - 8 , finger  112  extends from a tip of the actuator arm  78  to shift turbulent flow at the tip of the actuator arm  78 . Fingers  112  can be located in other regions of the head support (actuator arm or suspension) to protect the head support  70  from flow induced vibration along the flow path to the leading edge of the slider.  
         [0023]    Although a particular shaped finger  112  is shown, alternately shaped formations can be used to shift turbulence from the head support  70  and application is not limited to the exact shape and orientation shown. As shown in FIG. 9 for operation, the disc is rotated to create an air flow stream along the head support to the leading edge of the slider for recording as illustrated by block  120 . Air flow is constricted along the head support as illustrated by block  122  and is diverted from the head support to shield the head support from excitation as illustrated by block  124 . Air flow is diverted to shift turbulent air flow from the head support  70  so that the turbulent air flow does not excite or vibrate the head support  70 .  
         [0024]    A head actuator assembly  56  for a data head  60  for disc drive including at least one head support  70  extending in longitudinal alignment with opposed sides  90 ,  92  of the data head. The head gimbal support  70  including a base and an extended end for supporting the data head with the leading edge  86  of the head facing the head support  70  and a longitudinal extent of the head support being generally aligned along a flow path to a leading edge  86  of the data head  60 . The head actuator including a head support excitation shield  110  along the flow path to the leading edge  86  of the head to limit excitation of the head support  70 .  
         [0025]    It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this 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, the particular elements may vary depending on the particular application while maintaining substantially the same functionality without departing from the scope and spirit of the present invention. In addition, although the preferred embodiment described herein is directed to a magnetic disc drive system, it will be appreciated those skilled in the art that the teachings of the present invention can be applied to other systems, such as an optical disc drive system, without departing from the scope and spirit of the present invention.