Abstract:
Embodiments of the present invention include A head suspension assembly for a data storage device comprising a load beam and a Femto flexure coupled to the load beam, wherein the Femto flexure is a laminate structure comprising a support layer, the flexure comprising a plurality of symmetrical flexure legs, each of the flexure legs substantially hourglass shaped.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to transducer suspension systems and more particularly to a laminated suspension having improved lateral stiffness.  
       BACKGROUND OF THE INVENTION  
       [0002]     Disk drives are information storage devices that utilize at least one rotatable disk with concentric data tracks containing the information, a transducer (or head) for reading data from or writing data to the various tracks, and a transducer positioning actuator connected to the transducer for moving it to the desired track and maintaining it over the track during read and write operations. The transducer is attached to a slider, such as an air-bearing slider, which is supported adjacent to the data surface of the disk by a cushion of air generated by the rotating disk. The transducer can also be attached to a contact-recording type slider. In either case, the slider is connected to a support arm of the transducer-positioning actuator by means of a suspension.  
         [0003]     The suspension must meet several requirements. The suspension must be flexible and provide a bias force in the vertical direction. This is necessary to provide a compensating force to the lifting force of the air bearing in order to keep the slider at the correct height above the disk. Also, vertical flexibility is needed to allow the slider to be loaded and unloaded away from the disk. Another requirement of the suspension is that it must provide a pivotal connection for the slider. Irregularities in operation may result in misalignment of the slider. The slider is able to compensate for these problems by pitching and/or rolling slightly to maintain the proper orientation necessary for the air bearing. Another requirement of the suspension is that it must be rigid in the lateral direction. This is needed to prevent the head from moving side to side, which would result in the head reading the wrong track. Rigidity is also required to maintain slider position during high lateral shock events such as crash stop so that it does not slam into other parts of a disk drive.  
         [0004]     As disk drives have become smaller in size, the recorded track density has increased dramatically. This has necessitated the use of smaller and smaller heads and suspensions. However, these smaller geometries of the suspension and head make manufacture much more difficult. In particular, when moving from a Pico slider to a Femto slider, flexure pitch and roll stiffness and suspension spring rate have been reduced significantly. At the same time it is desirable to continue to use the same Stainless Steel thickness for a Femto flexure as for a Pico flexure due to proven manufacture yield. As a result, it is difficult to maintain acceptable lateral stiffness of the flexure. What is needed is a suspension design and method of manufacture that lends itself to reduced pitch and roll stiffness while simultaneously maintaining acceptable lateral stiffness.  
       SUMMARY OF THE INVENTION  
       [0005]     Embodiments of the present invention include a head suspension assembly for a data storage device comprising a load beam, a hinge, a base plate and a Femto flexure, wherein the Femto flexure is a laminate structure comprising a support layer, the flexure comprising a plurality of symmetrical flexure legs, each of the flexure legs substantially hourglass shaped. Since the embodiments apply to the heavy load-bearing layer of the flexure, which is currently the steel layer, they can as easily be applied to other flexure types including CIS, ILS, CAPS, FOS, etc. They can even be implemented on a wired suspension.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     The above and other objects and advantages of the present invention will be more readily appreciated from the following detailed description when read in conjunction with the accompanying drawings, wherein:  
         [0007]      FIG. 1  is a side view of a disk drive system and a controller unit in block form in accordance with embodiments of the present invention.  
         [0008]      FIG. 2  is a top view of one disk drive system in accordance with embodiments of the present invention.  
         [0009]      FIG. 3  is an illustration of exemplary flexure leg shapes in accordance with embodiments of the present invention.  
         [0010]      FIG. 4  is a top view of suspension assembly with an exemplary flexure leg shape in accordance with embodiments of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]     Reference will now be made in detail to embodiments of the present invention, a system and method for striping data, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.  
         [0012]     Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.  
         [0013]      FIGS. 1 and 2  show a side and a top view, respectively, of a disk drive system designated by the general reference number  110 . The disk drive system  110  comprises a plurality of stacked magnetic recording disks  112  mounted to a spindle  114 . The disks  112  may be conventional particulate or thin film recording disks or, in other embodiments, they may be liquid bearing disks. The spindle  114  is attached to a spindle motor  116 , which rotates the spindle  114  and disks  112 . A chassis  120  provides a housing for the disk drive system  110 . The spindle motor  116  and an actuator shaft  130  are attached to the chassis  120 . A hub assembly  132  rotates about the actuator shaft  130  and supports a plurality of actuator arms  134 . The stack of actuator arms  134  is sometimes referred to as a “comb”. A rotary voice coil motor  140  is attached to chassis  120  and to a rear portion of the actuator arms  134 .  
         [0014]     A plurality of suspension assemblies  150  are attached to the actuator arms  134 . A plurality of transducer heads, or sliders  152  are attached respectively to the suspension assemblies  150 . The sliders  152  are located proximate to the disks  112  so that, during operation, they are in electromagnetic communication with the disks  112  for reading and writing. The rotary voice coil motor  140  rotates actuator arms  134  about the actuator shaft  130  in order to move the suspension assemblies  150  to the desired radial position on disks  112 . The shaft  130 , hub  132 , arms  134 , and motor  140  may be referred to collectively as a rotary actuator assembly.  
         [0015]     A controller unit  160  provides overall control to system  110 . Controller unit  160  typically includes (not shown) a central processing unit (CPU), a memory unit and other digital circuitry, although it should be apparent that one skilled in the computer arts could also enable these aspects as hardware logic. Controller unit  160  is connected to an actuator control/drive unit  166  that in turn is connected to the rotary voice coil motor  140 . This configuration allows controller  160  to control rotation of the disks  112 . A host system  180 , typically a computer system, is connected to the controller unit  160 . The host system  180  may send digital data to the controller  160  to be stored on disks  112 , or it may request that digital data at a specified location be read from the disks  112  and sent to the system  180 . The basic operation of DASD units is well known in the art and is described in more detail in The Magnetic Recording Handbook, C. Dennis Mee and Eric D. Daniel, McGraw-Hill Book Company, 1990.  
         [0016]     When moving from a Pico slider to a Femto slider, the pitch and roll stiffness of a suspension are reduced generally as much as fifty percent or more from the Pico requirements. In order to do so, new laminates could be designed to achieve the desired pitch and roll characteristics. However, as a result, the lateral stiffness is compromised. In addition, the development of new laminates (e.g., 15-10-12 stainless steel-polyimide-copper) laminate results in unknown yields and could cause production problems when working with the new material.  
         [0017]     Embodiments of the present invention use a mass production laminate (20-10-12 stainless steel-polyimide-copper) with known yields. To achieve the desired pitch and roll stiffness that is required of a Femto slider, the stainless steel flexure legs are longer than the flexure legs of a Pico slider and use a novel flexure leg shape of the present invention to maintain a desired lateral stiffness.  FIGS. 3 and 4  illustrate novel shapes of the flexure legs in accordance with embodiments of the present invention.  
         [0018]     The present invention improves lateral stiffness of the flexure legs and keeps the pitch and roll stiffness essentially unchanged. The present invention enables the design of a Femto flexure using a thicker laminates such as 20-10-12 stainless steel-polyimide-copper with low enough pitch and roll stiffness. Simultaneously, the novel flexure leg shape of the present invention improves lateral stiffness of the flexure so that it does not fall below the minimum requirements.  
         [0019]      FIG. 3  is an illustration of exemplary flexure leg shapes in accordance with embodiments of the present invention. Shape one  300 A illustrates an exemplary flexure leg shape comprising a first width taper Y 1   320 , a mid section of minimal width and height H  330  and second width taper Y 2   310 . In one embodiment of the invention, shape one  300 A is approximately an hourglass shape with a mid section width H  330 . In one embodiment of the invention, the first width taper Y 1   320  linearly tapers from the left side towards the mid section H  330  where the first taper Y 1   320  meets a second taper Y 2   310 . In another embodiment of the invention, the second taper Y 2   310  linearly decreases from the right to the mid section H  330  and intersects Y 1   320  at midsection H  330 . Although the tapers are shown as linear, it is understood that they can also be curved.  
         [0020]     In one embodiment of the invention, midsection of minimal width and height H  330  is the narrowest width of the flexure leg. In one embodiment of the invention, the first taper Y 1   320  changes width at the same rate as Y 2   310 . In another embodiment of the invention, the rate of taper between Y 1   320  and Y 2   310  is different. In one embodiment of the invention, shape one  300 A can be manufactured from a laminate comprising 20-micron thick stainless steel and can be used in a Femto flexure. Shape one  300 A, even when made from conventional laminate comprising 20 micron thick stainless steel (conventionally used for manufacture of Pico flexures) provides the necessary pitch and roll stiffness while maintaining the correct lateral stiffness for Femto flexures.  
         [0021]     Shape two  300 B illustrates an exemplary flexure leg shape comprising a first width taper Y 1   320 , a mid section of height H  330  with a width W  340  and a second width taper Y 2   310 . In one embodiment of the invention, shape one  300 B is approximately an hourglass shape with a mid section comprising width H  330  and height H  330 . In one embodiment of the invention, the midsection of shape two  300 B is approximately rectangular. In one embodiment of the invention, the first width taper Y  1   320  linearly tapers from the left side towards the mid section of height H  330  and width W  340  where the first taper Y 1   320  and the second taper Y 2   310  meet at the midsection of width  340  and height  330 .  
         [0022]     In one embodiment of the invention, midsection dimension H  330  is the narrowest width of the flexure leg. In one embodiment of the invention, the first taper Y  1   320  changes width at the same rate as Y 2   310 . In another embodiment of the invention, the rate of taper between Y 1   320  and Y 2   310  is different. In one embodiment of the invention, shape one  300 B can be manufactured from a laminate comprising 20-micron (conventionally used for manufacture of Pico flexures) thick stainless steel and can be used in a Femto flexure. Shape one  300 B, even when made from conventional laminate comprising 20 micron thick stainless steel provides the necessary pitch and roll stiffness while maintaining the correct lateral stiffness for Femto flexures.  
         [0023]      FIG. 4  is a top view of a suspension comprising an exemplary flexure leg shape in accordance with embodiments of the present invention. In one embodiment of the invention, the flexure body  202  comprises a plurality of symmetrical flexure legs  222 . In one embodiment of the invention, the flexure body  202  comprises two symmetrical flexure legs  222 . In one embodiment of the invention, the flexure legs  222  are of shape one  300 A of  FIG. 3 . In this embodiment of the invention, the flexure of shape one  300 A comprises a first taper Y 1   320 , a second taper Y 2   310  and a mid section of height H  330 . In another embodiment of the invention, the flexure legs  222  are of shape two  300 B of  FIG. 3 . In this embodiment of the invention, the flexure of shape one  300 B comprises a first taper Y 1   320 , a second taper Y 2   310  and a mid section of width W  340  and height H  330 .  
         [0024]     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and it&#39;s practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.