Abstract:
Techniques for reducing weight while maintaining sufficient stiffness of a suspension assembly in provided. The suspension assembly includes a surface having a proximal end and distal end. A length is defined between the proximal end and the distal end. At least one support member (such as an edge rail) is formed to provide stiffness. The support member is contoured. In a specific embodiment, a portion of at least one cutout is disposed in at least one support member, and extends from the horizontal portion of the load beam member vertically into the at least one support member.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application claims priority from U.S. provisional patent application No. 60/510,315, filed Oct. 8, 2003, entitled “HDD Suspension Employing Contoured Rail and Mass Reduction Ports,” which disclosure is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to disk drives. More particularly, the invention provides a suspension assembly having weight reduction features while maintaining sufficient stiffness, which will result in improved suspension resonance, operational shock, and flow induced windage off-track. Merely by way of example, the invention is applied to hard disk drive apparatus, but it would be recognized that the invention has a much broader range of applicability. 
   A hard disc drive (HDD) unit generally uses a spinning storage medium (e.g., a disk or platter) to store data. A read-write head is positioned in close proximity to the spinning storage medium by a head stack assembly (HSA). Mounted on the HSA, a suspension assembly commonly includes a base plate, a load beam, and a flexure trace gimbal to which a slider is mounted. The slider supports the read-write head element. The load beam is generally composed of an actuator mounting section, a spring region and a rigid region. The spring region gives the suspension a spring force or preload counteracting the aerodynamic lift force created by the spinning medium during reading or writing. A gimbal is mounted at the distal end of the load beam and supports the slider allowing the head to have pitch and roll movement in order to follow the irregularities of the disk surface. 
   Demand generally requires increased HDD storage capacity, which generally compels higher track densities. Data tracks often become narrower and the spacing between data tracks on the storage medium decreases. An obstacle associated with increased track densities is accurate positioning of the read/write head over the desired track due to turbulent air streams generated by the spinning storage medium. It is therefore desirable to produce suspension assemblies with suitable stiffness and stability. 
   As can be seen from the above, improved techniques for a suspension assembly are needed. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention relates to disk drives. More particularly, the invention provides a suspension assembly having weight reduction features while maintaining sufficient stiffness. Merely by way of example, the invention is applied to hard disk drive apparatus, but it would be recognized that the invention has a much broader range of applicability. 
   The present invention according to an embodiment provides improved rails having a contoured height. This feature enables better utilization of mass, while providing the necessary stiffness in the center of the rail length, where bending stresses are generally maximum, and a decreasing height rail toward each end, where bending stresses generally taper off. Additionally, another embodiment of the present invention provides mass reduction cutouts, thereby improving stiffness to mass ratio of a load beam. Vibrational bending stresses are typically minimal at the base (forming radius location) of a formed rail, so these cutouts occupy a space that plays a small role in contributing stiffness to the suspension. These cutouts also allow air flows induced by the spinning storage medium to pass through the suspension assembly instead of being impeded as with a conventional rail. Accordingly, flow induced windage off-track can be reduced. These cutouts can be disposed in either or both the flat portion of the load beam and into the rails. 
   In an embodiment of the present invention, a load beam for a suspension assembly is provided. The load beam includes a flat portion having a proximal end and distal end. A length is defined between the proximal end and the distal end. First and second support members (such as rails) are formed on opposite edges of the load beam to provide stiffness. At least one cutout is disposed in each of the first and second support members. 
   In another embodiment of the present invention, a load beam for a hard disk drive apparatus includes a flat portion having a proximal end and distal end. First and second support members are formed on opposite edges of the load beam to provide stiffness. The first and second support members are each contoured as a curve in a direction perpendicular to the flat portion. 
   In yet another embodiment of the present invention, a hard disk drive apparatus is provided. The hard disk apparatus includes a voice coil motor, an arm member, and a load beam. The arm member has a first arm end and a second arm end, the second arm end being connected to the voice coil motor. The first arm end connects to a second end of the load beam. First and second edge rails of the load beam, to increase stiffness, each have an edge contoured as a curve and at least one aperture. An aperture, which includes without limitation a cutout, can be of any arbitrary shape. The hard disk apparatus also includes a read/write head connected to a first end of the load beam via a gimbal. 
   Many benefits are achieved by way of the present invention over conventional techniques. For example, the present technique provides an easy to use process that relies upon conventional technology. Additionally, the present invention uses a novel technique to reduce mass and flow induced windage off-track. Depending upon the embodiment, one or more of these benefits may be achieved. These and other benefits will be described in more throughout the present specification and more particularly below. 
   Various additional objects, features, and advantages of the present invention can be more fully appreciated with reference to the detailed description and accompanying drawings that follow. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a simplified hard disk drive apparatus according to an embodiment of the present invention; 
       FIG. 2  shows a simplified suspension assembly according to an embodiment of the present invention; 
       FIG. 3  shows a simplified suspension assembly according to an embodiment of the present invention; 
       FIGS. 4A and 4B  show top and bottom views of a load beam according to an embodiment of the present invention; and 
       FIGS. 5A ,  5 B, and  5 C shows views of a load beam according to an embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention relates to disk drives. More particularly, the invention provides a suspension assembly having weight reduction features while maintaining sufficient stiffness. Merely by way of example, the invention is applied to hard disk drive apparatus, but it would be recognized that the invention has a much broader range of applicability. 
     FIG. 1  is a simplified diagram of a disk drive apparatus  100  according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize other variations, modifications, and alternatives. Apparatus  100  includes at least one disk  102  (e.g., one, two, three, or more disks), at least one actuator arm  104  (e.g., one, two, three, or more actuator arms), and at least one suspension assembly  106  (e.g., one, two, three, or more suspension assemblies). Each suspension assembly is composed of a load beam  108 , flexure trace gimbal assembly (HGA)  110 , and base plate  112  (not shown). In this embodiment, load beam  108  includes contoured rails. Load beam  108  is generally a metal and, in a specific embodiment, stainless steel, although any suitable material could be employed. Base plate  112  connects the suspension assembly to an actuator arm  104 . Actuator arm  104  is generally aluminum. This diagram, as well as other diagrams provided herein, is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many other variations, modifications, and alternatives.  FIG. 1 , by example, depicts a desktop or server type of disk drive application, whereas a mobile disk drive may look substantially different, but would also benefit from the features of the present invention. 
   Disk  102 , commonly called a platter, rotates about a fixed axis (or spindle) from about 3,000 rpm up to about 15,000 rpm depending upon the embodiment. Disk  102  stores information and thus often includes a magnetic medium such as a ferromagnetic material. But, it can also include optical materials, common coated on surfaces of the disk, which become active regions for storing digital bit information. 
   The aggregate storage capacity of disk  102  will vary with track density and disk diameter. Disk  102  stores information in tracks which can be in a range of about 50,000 tracks per inch (TPI) to about 200,000 TPI, or more. The diameter of disk  102  can be 5.12 inches (e.g., for a 5.25 inch drive), 3.74 inches (e.g., for a 3.5 inch drive), or less than 2.5 inches, or even less than 1.8 inches or 1.0 inches, or even 0.85 inches. 
   Suspension assembly  106 , which overlies (or underlies) a surface of disk  102 , operates and controls a slider coupled to a read/write head (not shown). Flexure trace gimbal assembly  110  is attached to suspension assembly  106  which is in turn is connected to actuator arm  104 . Actuator arm  104  is connected to a voice coil motor or VCM, which moves suspension assembly  106  about a pivot point in an annular manner. The VCM can move at frequencies from DC up to about 1 kHz. Preferably, for higher track density, e.g., 200,000 TPI, the control bandwidth can approach 5 kHz, but can also be greater in certain embodiments. 
     FIG. 2  shows a simplified suspension assembly  200  according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize other variations, modifications, and alternatives. Load beam  202  includes support members  204 ,  206  formed on opposite edges. Support members  204 ,  206  substantially extend in a longitudinal direction from a proximal portion  208  to a distal portion  210 . In alternative embodiments, support members may extend along an entire length of load beam  202 , or any shortened portion thereof. A length of a support member can range from about 5 mm to about 15 mm according to a specific embodiment. 
   A height of the support members  204 ,  206  from surface  212  varies. In this specific embodiment, the height is contoured as an arc or curve, or polyline, combination of radii. Shaping support members in this way reduces the mass of the support members while retaining much of the stiffness of a conventional rail. It should be noted that in other specific embodiments, support members can be contoured in any arbitrary shape (such as non-linear shapes) to reduce mass. In addition, the support members are substantially perpendicular to a flat portion of the load beam. In another specific embodiment, the support member can be angled in a range from about 70 degrees to about 85 degrees, or more, with respect to surface  212 . 
   Referring again to  FIG. 2 , load beam  202  includes cutouts  214 . Cutouts  214  are disposed in a portion of support members  204 ,  206  (or side rails), as well as portion of surface  212 . Alternatively, cutouts can be disposed entirely within support members  204 ,  206 . Cutouts  214  reduce the mass of load beam  202  for improved shock and vibration frequency performance. In addition, cutouts  214  allow air flows generated by a spinning storage medium (such as a disk or platter) to pass through load beam  202  with less obstruction, thereby reducing flow induced windage off-track. In this specific embodiment, each support member  204 ,  206  includes two cutouts. In alternative embodiments, a support member may have one, three, four, or more cutouts. It should be noted that each support member of a load beam need not have an equal number of cutouts. For example, a first support member can include two cutouts, while a second support member can include three cutouts. Cutouts can also be offset with respect to the length of the load beam, between support members  204  and  206 . The dimensions of a cutout can vary with a specific application. In order to retain sufficient stiffness in a support member, a length of an individual cutout can range from about 0.2 mm to about 0.6 mm according to a specific embodiment. The aggregate length of all cutouts in a support member is preferably in a range of about 20% to 60% of the length of the support member according to another specific embodiment. Cutouts can be formed by mechanical milling, ion milling, laser ablating, and/or chemical etching portions of the load beam. 
     FIG. 3  shows a simplified suspension assembly  300  according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize other variations, modifications, and alternatives. In this specific embodiment of the present invention, load beam  302  at proximal portion  304  couples to unamount actuator arm  308 . Support members  310  extend from proximal portion  304  to distal portion  306 , before lift tip  312 . 
   Support members  310  includes a plurality of cutouts  314 . Cutouts  314  are disposed, at least partially, in support members  310 . Each of cutouts  314  are rectangular; however, in other embodiments, cutouts can take any arbitrary shape to reduce weight of the load beam and allow air flow to pass through the load beam. The distribution of cutouts along a length of a support member need not be even. In  FIG. 3 , the number of cutouts are weighted to proximal portion  304 . A set of seven cutouts  314  are separated by region  316  from a second set of three cutouts  314 . The absence of cutouts in region  316  provides additional stiffness in region  316 , where a different cutout serves a different purpose (lead edge axial limiter). 
     FIGS. 4A and 4B  show top and bottom views of a load beam  402  according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize other variations, modifications, and alternatives. A thin sheet of stainless steel can be used to manufacture load beam  402  having cutouts  414 . This sheet can be etched by photochemical etching to form the general shape of load beam  402  (or a plurality of load beams, which are later singulated). A forming operation (and/or a bending operation) is carried out on the metal sheet to permanently set the support members  410  to near a vertical position. Other features in the load beam  402  can also be formed in this step. 
     FIGS. 5A ,  5 B, and  5 C shows views of a load beam  500  according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize other variations, modifications, and alternatives. In this specific embodiment, cutouts disposed on the support members are slanted at an angle. Cutouts according to embodiments of the present invention may be at any arbitrary angle. 
   One of ordinary skill in the art would recognize many other variations, modifications, and alternatives. The above examples are merely illustrations, which should not unduly limit the scope of the claims herein. It is also understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims.