Abstract:
One aspect of the embodiments utilizes a disk apparatus employing a ramp loading method, which includes a ramp member having an overlapping portion with which a part of a disk having an information recording surface and a lateral side overlaps, and a groove is formed on the entire lateral side of the disk. The disk apparatus includes a protrusion formed on a portion of the overlapping portion of the ramp member that is opposed to the lateral side of the disk and the protrusion protrudes into the groove.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority to Japanese Patent Application No. 2007-304582, filed on Nov. 26, 2007, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The embodiments discussed herein are directed to a disk apparatus. More specifically, an aspect of the invention relates to a disk apparatus employing a ramp loading method for loading heads onto and unloading the heads from disks. 
         [0004]    2. Description of Related Art 
         [0005]    Hard disk drives (HDDs) are commonly used for computers as information recording apparatuses. Disk apparatuses, or the HDDs, read information from and write information onto disks with read/write heads. For the HDDs, the head is moved to a target position by an actuator with the head lifted above a recording surface of the disk that is spinning to read or write information. 
         [0006]    While the HDD is not in operation, in brief, the disks do not spin, and the heads are retracted to a position other than the recording surface of the disk to prevent the heads from contacting the recording surfaces. There have been two methods to retract the heads: one is the contact start-stop (CSS) method; and the other is the ramp loading method. The CSS method provides a parking zone at an internal radius of the disk where information is not written, then stops the heads by abutting the heads against the parking zone. The ramp loading method provides a ramp outside of the disk and retracts the heads onto the ramp. 
         [0007]    However, the CSS method has a disadvantage in that the disk and the head may deflect and crash upon an impact given externally. The head crash may damage the heads, deteriorating the head&#39;s read-write performance. 
         [0008]    Whereas, with the ramp loading method, the head is retracted within the ramp while the disk does not spin. Hence the head does not crash against the disk. Therefore, the ramp loading method is a natural choice for disk apparatuses such as portable HDDs used in a condition having a high frequency of vibration. 
         [0009]    Recently, magnetic disk apparatuses employing the ramp loading method used for portable devices such as laptop personal computers or music players have become smaller and thinner. As the devices and the players become more compact, clearances between recording surfaces of magnetic disks and ramps have become narrower. 
         [0010]    When a shock or a vibration is given externally to the magnetic disk apparatus, magnetic disks may crash against the ramp due to play of the fixed parts of the magnetic disks fixed onto the spindle or deflection of the magnetic disks. In addition to external causes, the magnetic disks may contact the ramp due to wobble of the magnetic disks called fluttering that is caused by airflow generated within the magnetic disk apparatus by the spinning disks. 
         [0011]    Due to contact and collisions between the magnetic disks and the ramp, the recording surfaces of the magnetic disks may be damaged. Additionally, the magnetic disks or the ramp may become worn and generate dust particles. If the dust particles collide with the heads, the heads may be damaged. 
         [0012]    To surmount this problem, there is a technique in which a ramp is designed to have protrusions formed on overlapping portions with which the edges of disks may contact (Cf. Patent document 1). With this technique, recording surfaces of the disks do not contact the ramp when the disks wobble. Instead, the tapered edges of the disks contact the protrusions of the ramp first. 
         [0013]    There have been other techniques in which a ramp is designed to have recesses formed on portions where the outermost edges of disks contact inner planes of the ramp, or where the outermost portions of the disks are tapered outwardly (Cf. patent document 2). This creates wider clearances between the disks and the ramp at those portions to keep the disks from contacting the ramp. 
         [0014]    [Patent document 1] Japanese Laid-open Patent 2006-12405 
         [0015]    [Patent document 2] Japanese Laid-open Patent 2006-323939 
         [0016]    For the technique disclosed in patent document 1, dust particles may be generated where the chamfered edges of the disks contact the protrusions of the ramp. In this case, the dust particles may be generated in the vicinity of the recording surfaces of the disks, and hence the dust particles may spread over the recording surfaces, and collide against the heads. 
         [0017]    For the technique disclosed in patent document 2, the disks may contact the ramp having the recesses therein to keep the outermost edges of the disk from contacting the ramp where the disks deflect greatly. Even if the outermost edges of the disks are tapered, the ramp may contact the disks with portions not tapered where the disks deflect the most. As the clearances between the disks and the ramp in the overlapping portions become narrower, inevitably, the disks may contact the ramp. 
         [0018]    The technique disclosed in the present embodiment is provided to address the problems mentioned above. An object of the embodiment is to provide the disk apparatus and the disk with which the recording surface of the disk may not be damaged due to contact with the ramp, and if dust particles are generated on the contact, the dust particles may not collide against the head. 
       SUMMARY 
       [0019]    In keeping with one aspect of an embodiment of this technique, a disk apparatus employing a ramp loading method includes a ramp member having an overlapping portion with which a part of a disk having an information recording surface and a lateral side overlaps, and a groove formed on the entire lateral side of the disk. The ramp includes a protrusion formed on a portion of the overlapping portion of the ramp member that is opposed to the lateral side of the disk, and the protrusion protrudes into the groove. 
         [0020]    Additional objects and advantages of the embodiments will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the embodiment. The object and advantages of the embodiment will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
         [0021]    It is to be understood that both the foregoing general description and the following detailed descriptions are exemplary and explanatory only and are not restrictive of the embodiment, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a plan view of the hard disk drive; 
           [0023]      FIG. 2  illustrates the ramp member and the periphery thereof; 
           [0024]      FIG. 3  is a perspective view of the ramp member and the periphery; 
           [0025]      FIG. 4  is a sectional view briefly illustrating the ramp member in which the magnetic disk is inserted; and 
           [0026]      FIG. 5  is a sectional view of the magnetic disk having rectangular-shaped groove on its lateral side. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    Referring to  FIGS. 1 and 2 , a structure of the disk apparatus in an embodiment of the present technique, a hard disk drive, will be disclosed.  FIG. 1  is a brief plan view illustrating the interior of the hard disk drive.  FIG. 2  is an enlarged plan view of the ramp member and the periphery shown  FIG. 1 . 
         [0028]    A hard disk drive  1  has an enclosure  2  in a box-shape, having a flat rectangular solid space therein. The enclosure  2  accommodates one or more magnetic disks  3  therein as information recording disks. The magnetic disks  3  are mounted onto a rotary shaft of a spindle mortar  4 . The spindle mortar  4  rotates the magnetic disks  3  at high speed, for example, 7,200 rpm or 10,000 rpm. The enclosure  2  has a lift, or a cover, not shown in  FIG. 1 , with which the internal space is sealed within the enclosure  2  and the cover. 
         [0029]    Within the enclosure  2 , carriages  5  whose tips are opposed to the recording surfaces of the magnetic disks  3  are accommodated. The carriage  5  has swing arms  7  which rotate about a spindle  6  and suspension arms  9  attached to the ends of the swing arms  7  supporting each of the head sliders  8  at their tips. The swing arms  7  are driven by an electromagnetic actuator  10  such as a voice coil mortar (VCM). As the swing arms  7  moves, the head sliders  8  traverse the magnetic disks  3  in a radial direction. Thus, a head slider  8  is positioned on a targeted recording track of the magnetic disk  3 . Typically, on both sides of the swing arm  7 , two head sliders  8  and therefore two head suspensions  9  are attached so as to be opposed to the neighboring magnetic disks  3  where a plurality of the magnetic disks  3  is mounted in the enclosure  2 . 
         [0030]    The load beams  11  are attached to the tips of the suspension arms  9  that are attached to the ends of the carriages  5 , extending forward from the suspension arms  9 . As the swing arms  7  move, the load beams  11  move together with the head sliders  8  in the radial direction of the magnetic disks  3 . 
         [0031]    Near the magnetic disks  3 , a ramp member  12  is provided on a path of the load beam  11  movement. When the head sliders  8  reach the rims of the magnetic disks  3 , load beam tips  11   a  of the load beams  11  slide on slopes  12   a  provided on the ramp member  12 . As the load beams  11  move away from the magnetic disks further, the load beam tips  11   a  of the load beams  11  slide up the slopes  12   a  gradually, and therefore the head sliders  8  are distanced from the magnetic disks  3 . After sliding up the slopes  12   a,  the load beam tips  11   a  of the load beams  11  moving in the radial direction outward are withdrawn into the recesses  12   b  and then stop. In this way, the head sliders  8  are retracted, and kept from contacting the magnetic disks  3  while the magnetic disks  3  do not spin. When the head sliders  8  move toward the magnetic disks  3 , the load beams  11  move in the radial direction of the magnetic disks  3  inward, sliding down the slopes  12   a  with the load beam tips  11   a  of the load beams  11 . Finally, the load beam tips  11   a  lift off the slopes  12   a  and the head sliders  8  are positioned over the magnetic disks  3 . Since the magnetic disks  3  spin at high speed while the heads is moving, the head sliders  8  are lifted with the airflow generated by the spinning magnetic disks  3 . As described above, a load-unload system is implemented by the load beams  11  and the ramp member  12 . 
         [0032]      FIG. 3  is the perspective view of the ramp member and the periphery. For simplification, only one of the suspension arms  9  is drawn in  FIG. 3 . The ramp member  12  has end portions  12   c  protruding over and under the outermost portions of the magnetic disks  3  so as to sandwich the disks. An overlapping portion  12   d  is formed between a pair of the end portions  12   c.  In other words, the magnetic disks  3  are rotatably supported with their edges inserted in the overlapping portions  12   d.  The portion near the edge is an area where no information is recorded. Thus, the head sliders  8  with magnetic heads fly over the recording surfaces of the magnetic disks  3  when the load beam tips  11   a  of the load beams  11  slide down the slopes  12   a  provided for the ramp member  12  and move away from the ramp member  12 . 
         [0033]    The ramp member  12  is typically made of resin, more specifically, a polyacetal resin whose coefficient of friction is low such as delrin. In general, the magnetic disk  3  is made of, from bottom to top, an aluminum or glass substrate, an underlayer, a magnetic layer, a protective layer, and a lubricant layer. 
         [0034]    In this embodiment, the grooves are formed on the lateral sides of the magnetic disks  3  circumferentially so that the protrusions formed in the overlapping portions  12   d  of the ramp member  12  protrude into the groove. The grooves and the protrusions will be disclosed with reference to  FIG. 4 .  FIG. 4  is the sectional view illustrating briefly the ramp member  12  in which the rim of the magnetic disk  3  is inserted. 
         [0035]    As described above, grooves  20  are formed on the lateral sides  3   a  of the magnetic disks  3  circumferentially without discontinuity. The grooves are formed in a tapered shape, viewed from the lateral side, gradually inclining inward, having flat bottom planes  20   a.    
         [0036]    The bottom planes  12   e  of the overlapping portions  12   d  are opposed to the lateral sides  3   a  of the magnetic disks  3  with only a slight clearance therebetween. 
         [0037]    In the middle of the bottom plane  12   e  of the overlapping portion  12   d,  a protrusion  22  that protrudes toward the groove  20  formed on the lateral side of the magnetic disk  3  is formed. Similar to the groove  20 , the profile of the protrusion  22  is in a tapered shape. Between the groove  20  and the side surfaces of the protrusion  22 , a clearance of a given dimension d is provided. 
         [0038]    The dimension D clearance between the magnetic disk  3  and the inner surfaces  12   f  of the overlapping portion  12   d  is greater than the dimension d of the clearance between the inner sides of the groove  20  and the side planes of the protrusion  22 . Thus, the dimensions are D&gt;d. As a result, the inside of the groove  20  formed on the lateral side of the magnetic disk  3  contacts the protrusion  22  if the magnetic disk  3  deflects or tilts to prevent the magnetic disk from deflecting or tilting further. Since the magnetic disk  3  cannot deflect or tilt further, a recording surface  3   b  of the magnetic disk  3  does not contact the ramp member  12 . Thus, the recording surface  3   b  of the magnetic disk  3  is kept from suffering damages. 
         [0039]    In the case where the thickness of the magnetic disk  3  ranges from 0.7 mm to 1.8 mm, the width of the portion of the magnetic disk  3  that is overlapped by the overlapping portion  12   d  of the ramp member  12  may be, for example, 1 mm. In this instance, the rim of the magnetic disk  3  1.2 mm to 1.3 mm inside from the lateral side  3   a  is the non-recording area, and the area inside the non-recording area is the recording area. Where the dimension D is 0.2 mm and the dimension d is 0.05 mm to 0.1 mm, D&gt;d is satisfied. Thus, the deflection and the tilt of the magnetic disk  3  are prevented effectively. 
         [0040]    Typically, the recording surface  3   b  of the magnetic disk  3  is coated with lubricant to reduce possible friction with the head slider to prevent damages to the magnetic disks  3 . In this embodiment, the lubricant is coated inside the grooves  20  and on the internal surfaces including the bottom planes. The lubricant reduces friction even if contact between the protrusion  22  and the inner surfaces of the groove  20  occurs. Thus, the protrusion  22  slides inside of the groove  20  smoothly. Therefore, damages to the contact portions and the generation of dust particles may be reduced. 
         [0041]    If dust particles are generated by contact with the groove  20  and the protrusion  22 , the dust particles may attach to the inner surfaces of the groove  20  on which the lubricant is coated. Thus, the dust particles may not gather over the recording surface  3   b  of the magnetic disk  3 , and collisions against the head slider or the magnetic head are prevented. 
         [0042]    Accordingly, the magnetic disk drive in this embodiment of the present technique prevents the deflection and tilt of the magnetic disk due to the vibration or shock, and therefore the damages to the recording surface  3   b  of the magnetic disk  3  may be reduced. Additionally, the magnetic disk  3  may contact the ramp member  12  with its groove  20  formed on the lateral side  3   a,  not on the recording surface  3   b.  Thus, the dust particles may not spread over the recording surface  3   b,  and so collisions with the magnetic head are reduced. Accordingly, a dust-resistant magnetic disk drive may be achieved. 
         [0043]    The profile of the groove  20  and the protrusion  22  are formed in a tapered shape. As such, the bottom basal portion of the protrusions  2  is thicker than its top portion, obtaining an increased strength. Since there is a possibility that the protrusion  22  contacts the magnetic disk  3 , the protrusion may be broken on contact if adequate strength is not ensured. In terms of shock-resistance, the tapered protrusion  22  is resistant to impacts because its basal portion is thicker. The angles of the tapered portions may be determined based on shapes or dimensions of the magnetic disk  3  or the ramp member. 
         [0044]    However, the profiles of the groove  20  and the protrusion  22  are not to be considered limited to the tapered shape as shown in  FIG. 4 . Alternatively, the profiles may be a rectangular shape as shown in  FIG. 5 . The inner surfaces of the groove  20  and the bottom plane  20   a  and the side surfaces and the top of the protrusion  22  are not necessarily flat, but may also be curvilinear. 
         [0045]    Where the profiles of the groove  20  and the protrusion  22  are formed in a rectangular shape, the protrusion may be extended to an allowable length in strength to increase the area of the side surfaces of the protrusion  22  that contacts the inner surfaces of the groove  20 . As the contact area increases, contact pressure per unit area decreases. The more friction between the disk  3  and the ramp member  12  is reduced, the more the dust particles decrease. 
         [0046]    In this embodiment, the magnetic disk drive is disclosed as a disk apparatus. However, this technique is applicable not only to magnetic disk apparatuses, but also to magneto-optical disk apparatuses or optical disk apparatuses. In other words, the technique disclosed in this application may be applicable not only to magnetic disks but also to information recording disks, for example, magneto-optical disks and optical disks. 
         [0047]    According to this technique, the recording surface of the disk may not contact the ramp member because the protrusion formed in the ramp member keeps the recording surface of the disk from contacting the ramp member. Further, if the protrusion of the ramp member contacts the inner surfaces of the groove and the dust particles are generated, the dust particles may stay in the groove. Therefore, dust collisions between the recording area and the head may be reduced. Accordingly, a vibration-proof and shock-resistant disk apparatus may be accomplished. 
         [0048]    Although the embodiments of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.