Abstract:
In a load/unload type disk drive, when a head for reading/writing information on a disk is retracted outside the disk by a swing arm at the time of stopping the operation of the disk drive, a ramp mechanism holds a lift tab provided at the tip of the swing arm, wherein the ramp mechanism comprises a holding member for holding the lift tab and a mounting member for mounting the holding member thereon, the mounting member having a guide capable of adjusting the mounting position. The holding member mounted on the mounting member is tentatively fastened thereto, with provisions made to be able to adjust the position of the thus mounted holding member by moving it along the guide in a direction conforming to the rotational path of the holding member.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation application based upon and claims priority of International application No. PCT/JP2007/056473, filed on Mar. 27, 2007, the contents being incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present invention relates to a storage device equipped with a ramp mechanism, and more particularly to a storage device, such as a load/unload type magnetic disk drive, that is equipped with a ramp mechanism for holding a slider-mounted magnetic head at a position near the outer diameter of a magnetic disk when the magnetic head is unloaded. 
       BACKGROUND 
       [0003]    Usually, in a computer, data is stored on an external storage device that can hold stored data even when power to the device is removed. Examples of such external storage devices include semiconductor memories, optical disks, and magnetic disk drives, among which magnetic disk drives are in widespread use because of their large storage capacity. Hard disk drives comprising data storage platters coated with a magnetic material and magnetic heads for reading and writing data on the platters are the predominant type of magnetic disk drive in use today. The platters employed with the hard disk drives are composed of a stack of aluminum or glass disks each coated with a magnetic material, and the magnetic heads are used to read and write data on the disks that are being rotated at high speed by a motor. 
         [0004]    There are two types of hard disk drives, the contact start/stop (CSS) type and the load/unload type. In the CSS type, when the magnetic disk is stationary, the magnetic head is in contact with the magnetic disk, but when the magnetic disk starts rotating, the magnetic head moves up and floats above the magnetic disk, and when the magnetic disk stops rotating, the magnetic head again contacts the magnetic disk. In the CSS type, the magnetic head lands on an inner diameter area (CSS zone) other than the data storage area of the magnetic disk. The head slider containing the magnetic head is provided with legs to prevent the entire structure of the slider from contacting the disk and sticking to it when the magnetic head lands on the magnetic disk. 
         [0005]    On the other hand, in the load/unload type, when the magnetic disk is stationary, the magnetic head attached at the tip of a swing arm, i.e., a magnetic head actuator, is unloaded from the magnetic disk surface, and when the magnetic disk starts rotating, the magnetic head is loaded onto the magnetic disk surface. In the load/unload type hard disk drive, a lift tab which is used to lift the magnetic head off the disk surface for unloading is provided in protruding fashion at the tip of the swing arm. A ramp mechanism for guiding and holding the lift tab thereon is provided within the housing of the hard disk drive at a position near the outer diameter of the magnetic disk. 
         [0006]    When the swing arm is turned toward the outer diameter of the magnetic disk to unload the magnetic head from the magnetic disk surface, the lift tab is guided by the ramp mechanism and held thereon thus keeping the magnetic head from contacting the magnetic disk. Such load/unload type hard disk drives are disclosed, for example, in U.S. Pat. No. 5,237,472 and U.S. Pat. No. 5,574,604. Generally, the load/unload type is widely used for magnetic disk drives of which impact resistance is demanded. 
         [0007]    In U.S. Pat. No. 5,237,472, the ramp mechanism is provided outside the outer diameter of the magnetic disk, while in U.S. Pat. No. 5,574,604, the ramp mechanism is located at the inner diameter of the magnetic disk. In U.S. Pat. No. 5,237,472, the ramp mechanism is fixed in a manner that permits it to be finely adjusted using a bolt inserted in a cross-shaped slot, while on the other hand, the ramp mechanism disclosed in U.S. Pat. No. 5,574,604 is rigidly fixed at two points. 
         [0008]    When the ramp mechanism is provided outside the outer diameter of the magnetic disk, as in the case of the ramp mechanism disclosed in U.S. Pat. No. 5,237,472, the ramp mechanism is constructed separately from the base, and the ramp mechanism is fixed by positioning it using two wall faces provided on the base of the housing of the hard disk drive. 
       SUMMARY 
       [0009]    However, with the fine adjustment structure for the ramp mechanism disclosed in patent document 1, the fine adjustment is achievable only in straight line directions, and the direction of the fine adjustment does not match the direction of movement of the magnetic head; on the other hand, when the ramp mechanism is fixed via the two wall faces to the base of the housing, there arises a problem that the mounting position of the ramp mechanism cannot be finely adjusted, resulting in an inability to properly retract the gimbal spring when unloading the head. If the mounting position of the ramp mechanism to the base cannot be optimally adjusted, the position where the lift tab contacts the ramp mechanism in sliding fashion may be displaced from the proper position depending on the accuracy with which the load beam is mounted to the head actuator, and the head slider may strike the magnetic disk surface. To change the ramp mechanism positioning, equipment for assembling the ramp mechanism, etc., has to be changed accordingly, which would involve a great deal of time and cost. 
         [0010]    It is also known that the sliding motion of the lift tab with respect to the ramp mechanism results in the generation of friction particles. In recent magnetic disk drives, since the flying height of the head is extremely small (for example, on the order of 10 nm), any friction particle falling on the magnetic disk could cause a head crash. Therefore, accurately positioning the ramp so as to permit the lift tab to slide along the ramp mechanism under favorable conditions is critical to prevent the generation of friction particles. 
         [0011]    To prevent the generation of friction particles, the area of contact between the ramp mechanism and the lift tab must be made relatively small. This makes it difficult to accurately position the ramp mechanism, and if the lift tab fails to correctly contact the ramp mechanism, excessive force may be applied to the lift tab and the contact point on the ramp mechanism when holding the head in position, and this can result in an inability to suppress the generation of friction particles. In addition to that, if an external impact is applied, the lift tab may, in a worst case, fall off the ramp mechanism. It is therefore important to correctly position the ramp mechanism within the housing so that the ramp can hold the head under favorable conditions. 
         [0012]    In view of the above, it is an object of the present invention to provide a storage device equipped with a ramp mechanism that permits the position of the ramp mechanism relative to the lift tab to be properly adjusted by making provisions so that the position of the holding member of the ramp mechanism for holding the lift tab, relative to the fixing portion provided on the base, can be finely adjusted in corresponding relationship with the movement of the swing arm, i.e., the head actuator, that moves the head. 
         [0013]    A storage device according to the present invention, which achieves the above object, is a storage device which, when in operation, reads and writes information on a storage medium by a head mounted at a tip of a swing arm and, when not in operation, retracts the head onto a ramp mechanism provided near an outer diameter of the storage medium, wherein the ramp mechanism comprises: a holding member having a ramp for holding a lift tab provided at a tip end of the swing arm; a mounting member provided on a base of the storage device and configured to mount the holding member thereon, the mounting member being provided with a guide that is used when moving the holding member in a direction conforming to a rotational path of the lift tab; and a fastening member for fastening the holding member to the mounting member. 
         [0014]    A storage device housing according to the present invention, which achieves the above object, is a housing for encasing a storage device which, when in operation, reads and writes information on a storage medium by a head mounted at a tip of a swing arm and, when not in operation, retracts the head onto a ramp mechanism provided near an outer diameter of the storage medium, wherein when the ramp mechanism includes a holding member having a ramp for holding a lift tab provided at a tip end of the swing arm, a mounting member for mounting the holding member thereon is formed integrally with a base of the housing, and the mounting member is formed by including a guide that is used when moving the holding member in a direction conforming to a rotational path of the lift tab. 
         [0015]    A storage device ramp mechanism according to the present invention, which achieves the above object, is a ramp mechanism for use in a storage device which, when in operation, reads and writes information on a storage medium by a head mounted at a tip of a swing arm and, when not in operation, retracts the head to a position near an outer diameter of the storage medium and holds the retracted head, wherein the ramp mechanism comprises: a holding member having a ramp for holding a lift tab provided at a tip end of the swing arm; a mounting member provided on a base of the storage device and configured to mount the holding member thereon, the mounting member being provided with a guide that is used when moving the holding member in a direction conforming to a rotational path of the lift tab; and a fastening member for fastening the holding member to the mounting member. 
         [0016]    According to the present invention, the position of the ramp mechanism relative to the lift tab can be properly adjusted by finely adjusting the fixing portion of the ramp mechanism relative to the base in relation with the movement of the head actuator that moves the magnetic head. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a plan view depicting one example of a prior art load/unload type hard disk drive. 
           [0018]      FIG. 2  is a perspective view depicting the configuration of a ramp mechanism in the load/unload type hard disk drive depicted in  FIG. 1 . 
           [0019]      FIG. 3  is a diagram illustrating the problem associated with the prior art ramp mechanism depicted in  FIG. 2 . 
           [0020]      FIG. 4  is an assembly diagram depicting the configuration of a ramp mechanism in a load/unload type hard disk drive according to a first embodiment of the present invention. 
           [0021]      FIG. 5  is a plan view depicting, together with the tip of a head actuator, the ramp mechanism of the present invention of  FIG. 4  in an assembled condition. 
           [0022]      FIG. 6  is a diagram depicting the configuration of a modified example of the ramp mechanism according to the first embodiment of the present invention depicted in  FIGS. 4 and 5 . 
           [0023]      FIG. 7  is an assembly diagram depicting the configuration of a ramp mechanism in a load/unload type hard disk drive according to a second embodiment of the present invention. 
           [0024]      FIG. 8  is a perspective view depicting the configuration of a modified example of the ramp mechanism in the load/unload type hard disk drive according to the second embodiment of the present invention. 
           [0025]      FIG. 9  is an assembly diagram depicting the configuration of a ramp mechanism in a load/unload type hard disk drive according to a third embodiment of the present invention. 
           [0026]      FIG. 10  is an assembly diagram depicting the configuration of a ramp mechanism in a load/unload type hard disk drive according to a fourth embodiment of the present invention. 
           [0027]      FIG. 11  is an assembly diagram depicting the configuration of a ramp mechanism in a load/unload type hard disk drive according to a fifth embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0028]    Before describing the preferred embodiments of the invention with reference to the accompanying drawings, the problem associated with the ramp mechanism employed in a typical prior art load/unload type hard disk drive will be described with reference to  FIGS. 1 to 3 . 
         [0029]      FIG. 1  is a diagram depicting one example of the prior art load/unload type hard disk drive  1 . At least one magnetic disk  4  as a storage medium is mounted at one side on a base  2  of the hard disk drive  11  and is rotated by a spindle motor; the magnetic disk  4  is composed of a large number of tracks for data recording. 
         [0030]    At the other side on the base  2  of the hard disk drive  1 , there is located a swing arm  5  that is equipped with a head (not depicted) for reading and writing data by accessing designated tracks on the magnetic disk  4 . The head is attached at the tip of the swing arm  5 . The swing arm  5  is rotatable about its axis of rotation  6 , and a voice coil motor  7  for driving the swing arm  5  is located on the opposite side of the axis of rotation  6  from the swing arm  5 . 
         [0031]    In the load/unload type hard disk drive  1 , the head is moved outside the magnetic disk  4  for unloading. For this purpose, in the load/unload type hard disk drive  1 , a ramp mechanism  30  for holding the tip of the swing arm  5  is provided on the base  2  at a position near the outer diameter of the magnetic disk  4 . The ramp mechanism  30  comprises a holding member  10  for holding the lift tab  9  provided at the tip of the swing arm  5  and a mounting member  20  for fixing the holding member  10  with respect to the base  2 . The mounting member  20  is located outside the magnetic disk  4 , while the holding member  10  is provided so as to partially overlap the magnetic disk  4 . 
         [0032]      FIG. 2  is a diagram depicting the configuration of the ramp mechanism  30  in the load/unload type hard disk drive  1  depicted in  FIG. 1 . The ramp mechanism  30  comprises the holding member  10  made of plastic and the mounting member  20  formed integrally with the base  2 . The mounting member  20  may be formed separately and rigidly fixed to the base  2 . The holding member  10  includes a ramp  11  for holding the lift tab  1  depicted in  FIG. 1  and a base portion  12  for mounting the holding member  10  to the mounting member  20 . The base portion  12  is rigidly fixed with a screw  8  to a notch  21  formed in the mounting member  20 . 
         [0033]      FIG. 3  is a diagram illustrating how the lift tab  9  provided at the tip of the swing arm  5  is held on the ramp  11  of the holding member  10  depicted in  FIG. 2 . The swing arm side of the ramp  11  is formed to provide a circumferential face that conforms to the rotational path T of the swing arm  5 . As a result, the lift tab  9  of the swing arm  5  rides over the ramp  11  as the swing arm  5  rotates, and thus the lift tab  9  is held in position outside the magnetic disk. 
         [0034]    However, in the prior art hard disk drive  1 , since the three axes x, y, and z of the holding member  10  are all fixed to the mounting member  20 , it has not been possible to finely adjust the mounting position of the holding member  10  relative to the mounting member  20 . The inability to finely adjust the mounting position of the holding member  10  has lead to the problem that when the position where the lift tab  9  contacts the ramp  11  in sliding fashion is displaced from the proper position depending on such factors as the mounting accuracy of the suspension attached at the tip of the swing arm  5 , the position cannot be corrected to the proper position. As a result, the prior art has had the problem that if the positioning between the lift tab  9  and the ramp  11  is to be changed, equipment for assembling the ramp mechanism, etc. has to be changed accordingly, and the time and cost involved can be substantial. 
         [0035]    The present invention permits the position of the holding member  10  of the ramp mechanism  30  relative to the fixing portion  20  to be finely adjusted in corresponding relationship with the movement of the swing arm, and typical embodiments of the invention are illustrated in  FIGS. 4 to 11 . In the description of each embodiment of the invention, the same component members as those of the prior art ramp mechanism described with reference to  FIGS. 1 to 3  are designated by the same reference numerals. 
         [0036]      FIG. 4  is an assembly diagram depicting the configuration of a ramp mechanism  30  in a load/unload type hard disk drive according to a first embodiment of the present invention. In the first embodiment, the mounting hole opened through the base portion  12  of the holding member  10  is provided in the form of an elongated hole  13 , and the elongated hole  13  is curved so as to lie on the circumference of a circle centered about the axis of rotation (not depicted) of the swing arm  5  when the holding member  10  is mounted on the mounting member  20 . Further, a rear face  12 A of the base portion  12  which is opposite from the ramp  11  is also formed to provide a circumferential face having the same curvature as the circle centered about the axis of rotation of the swing arm  5 . 
         [0037]    On the other hand, the mounting member  20  comprises a high wall portion  22  and a low wall portion  23 , and is formed so that the base portion  12  of the holding member  10  is placed in the notch  21  bounded by a top face  23 T of the low wall portion  23  and a sidewall of the high wall portion  22 . Then, an inner circumferential face  22 A of the high wall portion  22 , which faces the rear face  12 A of the base portion  12 , is formed as a curved face having the same curvature as the rear face  12 A of the base portion  12 . The top face  23 T of the low wall portion  23  is provided with a screw hole  24  in a position over which the base portion  12  of the holding member  10  is placed. In this embodiment, an inner circumferential face  23 A of the low wall portion  23  is also formed as a curved face having the same curvature as the circle centered about the axis of rotation of the swing arm  5 ; in this case, the rear face side of the ramp  11  should also be formed as a curved face having the same curvature. If the rear face side of the ramp  11  is not a curved face, then the inner circumferential face  23 A need not be limited to any specific shape as long as it does not interfere with the movement of the ramp  11 . 
         [0038]    The thus constructed holding member  10  is placed in the notch  21  of the mounting member  20  by holding the rear face  12 A of the base portion  12  against the inner circumferential face  22 A of the high wall portion  22 . Then, the screw  8  is inserted through a washer  38  into the elongated hole  13 , and threaded into the screw hole  24  formed in the top face  23 T of the low wall portion  23 ; the screw  8  is then gently tightened to tentatively fasten the holding member  10  to the mounting member  20 . This condition is illustrated in  FIG. 5 . 
         [0039]    After that, the holding member  10  is moved for fine adjustment in the direction of arrow B within the notch  21  so that the lift tab  9  will be properly held on the ramp  11  when the swing arm  5  comes to the unload position; then, the screw  8  is securely tightened in the proper position to fix the holding member  10  onto the mounting member  20 . Since the screw hole  13  and the rear face  12 A of the base portion  12 , and thus the inner circumferential face  22 A of the high wall portion  22 , lie on concentric circles centered about the axis of rotation of the swing arm  5 , the movement of the holding member  10  in the direction of arrow B matches the direction of movement of the lift tab  9 . Accordingly, after temporarily fastening the holding member  10  to the mounting member  20 , the position of the ramp  11  can be adjusted to the optimum position along the direction of movement of the lift tab  9 . Generally, the distance over which the ramp  11  is moved for fine adjustment is about 1 to 2 mm. 
         [0040]      FIG. 6  is a diagram depicting the configuration of a modified example of the ramp mechanism  30  according to the first embodiment of the present invention depicted in  FIGS. 4 and 5 . In the ramp mechanism  30  according to the first embodiment of the invention depicted in  FIGS. 4 and 5 , since there is a suitable gap between the screw hole  13  and the shaft of the screw  8 , only the inner circumferential face  22 A of the high wall portion  22  can, in effect, serve as a guide when moving the holding member  10  in the direction of arrow B within the notch  21 , so that the holding member  10  is moved by allowing the rear face  12 A of the base portion  12  to slide along the inner circumferential face  22 A of the high wall portion  22 . 
         [0041]    The modified example depicted in  FIG. 6  provides an additional member that serves as a guide when moving the holding member  10  in the direction of arrow B within the notch  21 . That is, in this modified example, a guide protrusion  14  is provided in protruding fashion on a bottom face  12 B of the base portion  12  of the holding member  10  at a position spaced away from the rear face  12 A, and a guide groove  25  with the same curvature as the circle centered about the axis of rotation of the swing arm  5 , and with the groove width equal to the diameter of the guide protrusion  14 , is formed in the top face  23 T of the low wall portion  23  at a position corresponding to the guide protrusion  14 . 
         [0042]    According to this configuration, since two members, the guide groove  25  and the inner circumferential face  22 A of the high wall portion  22 , serve as the guides when moving the holding member  10  in the direction of arrow B within the notch  21 , the holding member  10  can be moved within the notch  21  in a stable manner. 
         [0043]      FIG. 7  is an assembly diagram depicting the configuration of a ramp mechanism  30  in a load/unload type hard disk drive  1  according to a second embodiment of the present invention. In the second embodiment, as in the first embodiment, the mounting hole opened through the base portion  12  of the holding member  10  is provided in the form of an elongated hole  13  which is curved so as to lie on the circumference of a circle centered about the axis of rotation of the swing arm  5 . In the second embodiment, the rear face  12 A of the base portion  12  which is opposite from the ramp  11  need not be formed as a curved face but may be formed as a planar face. 
         [0044]    On the other hand, in the second embodiment, the bottom face  12 B of the base portion  12  of the holding member  10  is provided with a guide protrusion (rail)  15  that is curved like an arc so that its inner and outer circumferential faces lie on concentric circles centered about the axis of rotation of the swing arm  5 . The mounting member  20  which receives the holding member  10  is constructed from a low wall portion  23 , except for an end portion formed as a stopper wall  22 S that limits the movement of the holding member  10 . The top face  23 T of the low wall portion  23  is provided with a screw hole  24  in a position aligned with the elongated hole  13  of the holding member  10 , and a guide groove  26  as a curved groove whose inner and outer circumferential faces lie on concentric circles centered about the axis of rotation of the swing arm  5 , and along which the guide rail  15  can be moved in sliding fashion, is formed in a portion that faces the guide rail  15 . 
         [0045]    The ramp mechanism  30  of the second embodiment is assembled by inserting the guide rail  15 , provided in protruding fashion on the bottom face  12 B of the base portion  12  of the holding member, into the guide groove  26  formed in the mounting member  20 . Then, the screw  8  is inserted through the washer  38  into the elongated hole  13 , and threaded into the screw hole  24  formed in the top face  23 T of the low wall portion  23 ; the screw  8  is then gently tightened to tentatively fasten the holding member  10  to the mounting member  20 . After that, the holding member  10  can be securely fixed to the mounting member  20  in the same manner as in the first embodiment. 
         [0046]      FIG. 8  is a perspective view depicting the configuration of a modified example of the ramp mechanism  30  in the load/unload type hard disk drive  1  according to the second embodiment of the present invention. The only difference between the modified example depicted in  FIG. 8  and the second embodiment depicted in  FIG. 7  is the shape of the holding member  10 . More specifically, in the holding member  10  of the second embodiment, the arc-shaped guide rail  15  is provided on the bottom face  12 B of the base portion  12 , but in the modified example of the second embodiment, instead of the guide rail  15 , two guide protrusions  16  are provided in protruding fashion on the bottom face  12 B of the base portion  12 . Needless to say, the diameter of each of the two guide protrusions  16  is equal to the groove width of the guide groove  26  formed in the mounting member  20 , and their positions lie on the circumference of the same circle centered about the axis of rotation of the swing arm. 
         [0047]      FIG. 9  is an assembly diagram depicting the configuration of a ramp mechanism  30  in a load/unload type hard disk drive  1  according to a third embodiment of the present invention. In the third embodiment, as in the first embodiment, the mounting hole opened through the base portion  12  of the holding member  10  is provided in the form of an elongated hole  13  which is curved so as to lie on the circumference of a circle centered about the axis of rotation of the swing arm  5 . In the third embodiment, the rear face  12 A of the base portion  12  which is opposite from the ramp  11  need not be formed as a curved face but may be formed as a planar face. 
         [0048]    On the other hand, in the third embodiment, the bottom face  12 B of the base portion  12  of the holding member  10  is provided with a guide groove  17  that is curved like an arc so that its inner and outer circumferential faces lie on concentric circles centered about the axis of rotation of the swing arm  5 . The mounting member  20  which receives the holding member  10  is constructed from a low wall portion  23  except an end portion formed as a stopper wall  22 S that limits the movement of the holding member  10 . The top face  23 T of the low wall portion  23  is provided with a screw hole  24  in a position aligned with the elongated hole  13  of the holding member  10 , and an arc-shaped guide protrusion (rail)  27  whose inner and outer circumferential faces lie on concentric circles centered about the axis of rotation of the swing arm  5 , and which can be inserted in the guide groove  17  and moved along it in sliding fashion, is formed in a portion that faces the guide groove  17 . 
         [0049]    To assemble the ramp mechanism  30  of the third embodiment, the guide rail  27  provided on the mounting member  20  is inserted into the guide groove  17  formed in the bottom face  12 B of the base portion  12  of the holding member. Then, the screw  8  is inserted through the washer  38  into the elongated hole  13 , and threaded into the screw hole  24  formed in the top face  23 T of the low wall portion  23 ; the screw  8  is then gently tightened to tentatively fasten the holding member  10  to the mounting member  20 . After that, the holding member  10  can be securely fixed to the mounting member  20  in the same manner as in the first embodiment. 
         [0050]    Though not depicted or described in detail herein, in a modified example of the configuration of the third embodiment of the present invention, a plurality of guide protrusions may be formed on the top face  23 T of the low wall portion  23  instead of the guide rail  27  provided on the mounting member  20 , just like the guide protrusions  16  depicted in  FIG. 8  are provided instead of the guide rail  15  depicted in  FIG. 7 . 
         [0051]      FIG. 10  is an assembly diagram depicting the configuration of a ramp mechanism in a load/unload type hard disk drive  1  according to a fourth embodiment of the present invention. In the fourth embodiment, the mounting member  20  comprises a low wall portion  23  and a high wall portion  22  higher than the low wall portion  23 , the high wall portion  22  being formed on the inner side of the low wall portion  23  (that is, on the side nearer to the lift tab). The outer circumferential face of the high wall portion  22  is formed as a circumferential face whose center of curvature is at the axis of rotation of the swing arm, the circumferential face thus providing a guide face  22 B. Likewise, the inner circumferential face  22 A of the high wall portion  22  is also formed as a circumferential face whose center of curvature is at the axis of rotation of the swing arm, the circumferential face thus providing a guide face; to match the thus formed face, a rear face  19  of a portion forming the ramp  11  on the holding member  10 , the rear face  19  being a part to be placed against the inner circumferential face (guide face)  22 A of the high wall portion  22 , is formed as a curved face having the same curvature as the inner circumferential face  22 A of the high wall portion  22 . The outer circumferential face  23 B of the low wall portion  23  may also be formed as a circumferential face whose center of curvature is at the axis of rotation of the swing arm, or may be formed as some other curved face or as a planar face. 
         [0052]    On the other hand, an elongated hole  13 , similar to the one formed in the first to third embodiments, is formed through the holding member  10 , and a protruding rail  18  protruding toward the low wall portion  23  is formed along the outer circumferential edge of the bottom face  12 B of the base portion  12 . The inner circumferential face  18 A of the protruding rail  18  is formed so as to match the shape of the outer circumferential face (guide face)  22 B of the high wall portion  22 . A screw hole  24  is formed in the top face  22 T of the high wall portion  22 , and a stopper wall  28  higher than the high wall portion  22  is formed at an end of the high wall portion that is nearer to the disk. 
         [0053]    To assemble the ramp mechanism  30  of the fourth embodiment, the rear face  19  of the portion forming the ramp  11  on the holding member  10  is brought close to the mounting member  20  in such a manner as to slide along the inner circumferential face  22 A of the high wall portion  22 , and the inner circumferential face  18 A of the protruding rail  18  provided on the bottom face  12 B of the base portion  12  of the holding member is made to fit against the outer circumferential face  22 B of the high wall portion  22  of the mounting member  20 . 
         [0054]    As a result, with the inner circumferential face  22 A and outer circumferential face  22 B of the high wall portion  22  serving as guides, the holding member  10  can be fitted onto the mounting member  20  and moved along the circumferential direction of a circle centered about the axis of rotation of the swing arm. Then, the screw  8  is inserted through the washer  38  into the elongated hole  13 , and threaded into the screw hole  24  formed in the top face  23 T of the low wall portion  23 ; the screw  8  is then gently tightened to tentatively fasten the holding member  10  to the mounting member  20 . After that, the holding member  10  can be securely fixed to the mounting member  20  in the same manner as in the first embodiment. 
         [0055]      FIG. 11  is a plan view depicting the configuration of a ramp mechanism in a load/unload type hard disk drive  1  according to a fifth embodiment of the present invention. The fifth embodiment is identical to the first embodiment depicted in  FIG. 5 , except that a moving mechanism  40  for moving the holding member  10  is added at one end of the base portion  12  of the holding member  10  in the ramp mechanism  30  of the first embodiment. Since the configuration of the ramp mechanism  30  of the first embodiment has already been described, the description will not be repeated. 
         [0056]    The moving mechanism  40  for the holding member  10  comprises a rack  41  formed in protruding fashion on the base portion  12  of the holding member  10 , a pinion  42  that has its axis of rotation on the top face  23 T of the low wall portion  23  of the mounting member  20  and engages with the rack  41 , and a driving gear  43  that has its axis of rotation on the top face  23 T of the low wall portion  23  of the mounting member  20  and engages with the pinion  42  for rotation. The rack  41  is curved to conform to the circumference of a circle centered about the axis of rotation of the swing arm. 
         [0057]    In this embodiment, the diameter of the pinion  42  is increased to increase the number of its teeth and the diameter of the driving gear  43  is reduced to reduce the number of its teeth, thereby reducing the number of revolutions of the pinion  42  relative to the number of revolutions of the driving gear  43  so that the movement of the rack  41  can be finely adjusted. Further, the driving gear  43  has a hexagonal slot  44  so that it can be easily rotated from outside by using a tool such as a hexagonal wrench. The larger the ratio of the number of teeth on the pinion  42  to the number of teeth on the driving gear  43 , the easier the fine adjustment. 
         [0058]    The moving mechanism  40  for the holding member  10  can not only be added to the first embodiment, but also be added to the ramp mechanism  30  of any of the second to fourth embodiments. In each of the above embodiments, a screw has been used to fasten the holding member to the mounting member, but the fastener used to fasten the holding member to the mounting member is not limited to a screw, but an adhesive may be used to bond them together if no further adjustment is needed once the position of the holding member relative to the mounting member has been adjusted.