Abstract:
A support structure with enhance vibrational response. In accordance with some embodiments, an apparatus includes a data storage medium and a magnetic head to write to or read from the medium. The head has a first side and a second side opposite the first side, the first side being closer to a center of the medium than the second side. An actuator is adapted to tilt the first side of the head closer to a surface of the medium than the second side of the head.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2009-0037111, filed on Apr. 28, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     1. Field of the Invention 
     The present general inventive concept relates to a hard disk drive, and more particularly, to a hard disk drive including a head stack assembly (HSA) having reduced off-track. 
     2. Description of the Related Art 
     A hard disk drive is an auxiliary memory device used in computers, MP3 players, or mobile phones that reads data stored in a disk. During operation of the hard disk drive, the head slider floats a predetermined distance above the disk and reads the data stored in the disk, or writes data into the disk, by using a magnetic head in the head slider to reproduce the data. A head stack assembly supports the head slider which is mounted on a front edge thereof and moves the head slider to a predetermined position on the disk. 
     When the hard disk drive is physically disturbed or when the head stack assembly accidentally vibrates, the magnetic head may skip from a certain track. A situation in which the magnetic head skips from the track it is supposed to be reading from or writing to is referred to as off-track. 
       FIG. 1  is a diagram illustrating an off-track caused by disk vibration. 
     Referring to  FIG. 1 , when a writing or reading operation is performed, the magnetic head  127 ( d   0 ) on the head slider  27  and a certain track T(d 0 ) located on a concentric circle about the center of the disk  10  may both be located on a vertical line VL. Since the magnetic head  127 ( d   0 ) and the track T(d 0 ) are located along the same plane in a horizontal direction at this time, off-track of the head slider  27 , or more specifically, of the magnetic head  127 ( d   0 ), is 0. When the hard disk drive vibrates, an outer circumference of the disk  10  and the head slider  27  of the head stack assembly vibrate in a vertical direction to cause the magnetic head  127  to move off-track. In particular, when the disk  10  and the head slider  27  vibrate downward, a track T(d 1 ) moves toward the outer circumference of the disk  10  while the magnetic head  127 ( d   1 ) moves toward the center of the disk  10 , causing the magnetic head  127  to move off-track. 
     In the above example, the element label  127 ( d   0 ) indicates that the magnetic head  127  is located at a certain distance from the center of the disk  10  in a resting state (d 0 ). When the disk  10  vibrates downward, the magnetic head  127  moves a distance from the center of the disk  10  and is in a first vibration state (d 1 ). The track T(d 1 ) may move due to slight amounts of flexion or expansion of the disk  10  during vibration, for example. 
     On the other hand, when the disk  10  and the head slider  27  vibrate upward, a track T(d 2 ) moves toward the center of the disk  10  while the magnetic head  127 ( d   2 ) moves toward the outer circumference of the disk  10 , so that the magnetic head is forced off-track. Movement of the track T(d 2 ) may be caused by a slight compression of the disk surface during vibration, for example. A positioning error signal (PES) caused by the off-track adversely affects reliability of data writing/reading qualities of the hard disk drive. 
     SUMMARY 
     The present general inventive concept is generally directed to a support structure with enhanced vibrational response. In accordance with some embodiments, an apparatus includes a data storage medium and a magnetic head to write to or read from the medium. The head has a first side and a second side opposite the first side the first side being, closer to a center of the medium than the second side. An actuator is adapted to tilt the first side of the head closer to a surface of the medium than the second side of the head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present general inventive concept will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a diagram illustrating an off-track caused by disk vibrations; 
         FIG. 2  is a plan view of a hard disk drive according to an embodiment of the present inventive concept; 
         FIGS. 3 and 4  are expanded perspective views of a part of a head stack assembly according to an embodiment of the present inventive concept, wherein  FIG. 3  is an upper side perspective view and  FIG. 4  is a bottom perspective view; 
         FIG. 5  is a diagram illustrating an off-track reducing effect of the head stack assembly shown in  FIG. 4 ; 
         FIG. 6  illustrates a head stack assembly according to an embodiment of the present general inventive concept; 
         FIGS. 7A and 7B  illustrate a computing unit and an interface according to an embodiment of the present general inventive concept; 
         FIGS. 8A and 8B  illustrate a head slider and a magnetic head according to the present general inventive concept; 
         FIGS. 9A and 9B  illustrate a method of manufacturing a head stack assembly according to an embodiment of the present general inventive concept; and 
         FIGS. 10A and 10B  illustrate a method of manufacturing a head stack assembly according to another embodiment of the present general inventive concept. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present inventive concept will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The inventive concept may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Like reference numerals refer to like elements throughout. 
     Referring to  FIGS. 2 through 4 , the hard disk drive  100  includes a spindle motor  105 , a data storage medium  107 , such as a disk, and a head stack assembly  110  in a housing including a base member  101  and a cover member (not shown) coupled to the base member  101 . The spindle motor  105  rotates the disk  107  at a high speed, and is attached to the base member  101 . The disk  107  is coupled to the spindle motor  105  to rotate in a direction denoted by an arrow at high speed. Due to the high speed rotation, an air flow which flows in the same direction as the direction denoted by the arrow is induced on a surface of the disk  107 . 
     The head stack assembly  110  (also referred to herein as an “actuator”) includes a head slider  130  on which a magnetic head (not shown) performing operations of writing/reading data is located. The head slider  130  records data onto the disk  107  or reproduces (reads) data from the disk  107  after moving to a certain track on the disk  107 . The head stack assembly  110  includes a swing arm  113  in which a pivot bearing  111  is inserted to he rotatably mounted on the base member  101 . a connecting plate  115  coupled to a front edge of the swing arm  113 . a suspension  120  coupled to the connecting plate  115  to vibrate finely, and the head slider  130  mounted on a front edge of the suspension  120 . In addition, the head stack assembly  110  includes an over-mold  134  which is coupled to the swing arm  113  and includes wound voice coil  135 . 
     A magnet  137  and a yoke  138  supporting the magnet  137  are located on upper and lower portions of the over-mold  134 . The magnet  137 , the yoke  138 , and the voice coil  135  of the head stack assembly  110  form a voice coil motor to provide a driving force for rotating the head stack assembly  110 . 
     When the air flow caused by the high speed rotation of the disk  107  passes over the surface of the disk  107  and a surface of the head slider  130  facing the disk  107 , a lifting force is applied to the head slider  130 . The head slider  130  maintains the floating status at a height where the lifting force and the elastic compressing force of the suspension  120  which compresses the head slider  130  toward the disk  107  are balanced. During the floating status of the head slider  130 , the magnetic head (not shown) on the head slider  130  performs the recording or reproducing function of the data with respect to the disk  107 . The hard disk drive  100  may further include a flexible printed circuit (FPC)  145  which electrically connects the head stack assembly  110  to a main circuit board (not shown) under the base member  101 . 
     The connecting plate  115  connects the front edge portion of the swing arm  113  to the suspension  120 , and the front edge portion of the swing arm  113  and the connecting plate  115  may be connected to each other by a swaging operation using a swaging hole  118 . 
     The hard disk drive  100  further includes a pair of hinges  123  and  124  which connect the connecting plate  115  to the suspension  120 . The hinges  123  and  124  are located on both sides of a center line CL of the suspension  120 . The center line CL extends in a length direction of the suspension  120 , and the center line CL is a virtual straight line extending from the head slider  130  to the pivot bearing  111 . The first hinge  123  is located on a side which is relatively closer to the center of the disk  107 , or to the spindle motor  105 , than the center line CL is. The second hinge  124  is located on a side which is relatively farther from the center of the disk  107 , or the spindle motor  105 , than the center line CL is. 
     Referring to  FIG. 3 , a thickness T 1  of the first hinge  123  may be greater than a thickness T 2  of the second hinge  124 . Processes of fabricating the connecting plate  115  and the pair of hinges  123  and  124  will be described as follows. An insulating layer  126  is deposited on a surface of a first metal layer  125  which is formed of a metal material such as stainless steel, and a second metal layer  127  is deposited on a surface of the insulating layer  126 . A plate (not shown) may be connected to the connecting plate  115  and the pair of hinges  123  and  124  by using a pressing operation. In addition, a region where the second hinge  124  is formed may be etched to remove the second metal layer  127  and the insulating layer  126 , and accordingly, the connecting plate  115  and the pair of hinges  123  and  124  may be formed. 
     The connecting plate  115 , the first hinge  123 , and the second hinge  124  may all include the first metal layer  125 . In addition, the connecting plate  115  and the first hinge  123  each include the insulating layer  126  deposited on the first metal layer  125  and the second metal layer  127  deposited on the insulating layer  126 . However, the second hinge  124  does not include the insulating layer  126  and the second metal layer  127 . Therefore, the thickness T 2  of the second hinge  124  is less than the thickness T 1  of the first hinge  123 . In the embodiment illustrated in  FIGS. 3 and 4 , the thickness T 1  of the first hinge  123  is the same as a thickness of the connecting plate  115 . However, the present inventive concept is not limited to the above example. 
     Although it is not shown in the drawings, the suspension  120  may include a load beam which elastically biases the head slider  130  toward the surface of the disk  107  and a flexure supported by the load beam and attaching the head slider  130  to the surface facing the disk  107 . The load beam may be coupled to the pair of hinges  123  and  124 . 
       FIG. 5  is a diagram illustrating the off-track reducing effect of the head stack assembly shown in  FIGS. 3 and 4 . Referring to  FIG. 5 , when the disk  107  shakes, the head slider  130  shakes along a normal line NL to the surface of the head slider  130  facing the disk  107 . Since the first hinge  123  (refer to  FIG. 4 ) is thicker than the second hinge  124  (refer to  FIG. 4 ), the normal line NL is slightly slanted with respect to vertical lines VL 1 , VL 2 , and VL 3 . 
     When the disk  107  and the head slider  130  shake due to the vibrations applied to the hard disk drive  100  (refer to  FIG. 2 ), the magnetic head  127 ( d   0 ) formed on the head slider  130  and a certain track T(d 0 ) may be located on the first vertical line VL 1  in a state where the disk  107  is in a horizontal mode (refer to (i) of  FIG. 5 ). Therefore, at this time, the off-track may be 0. On the other hand, when the disk  107  is in a downward vibration mode, that is, an outer circumference of the disk  107  is descended (refer to (ii) of  FIG. 5 ), the magnetic head  127 ( d   1 ) formed on the head slider  130  and the certain track T(d 1 ) may be located on the second vertical line VL 2 . Although the magnetic head  127 ( d   1 ) and the certain track T(d 1 ) are not located on the first vertical line VL 1 , they are located on the second vertical line VL 2 , and accordingly, the off-track may be 0. Also, when the disk  107  is in an upward vibration mode, that is, the outer circumference of the disk  107  is ascended (refer to (iii) of  FIG. 5 ), the magnetic head  127 ( d   2 ) and the certain track T(d 2 ) may be located on the third vertical line VL 3 , and accordingly, the off-track may still be 0. When comparing the case shown in  FIG. 5  with the conventional head slider shown in  FIG. 1 , since the head slider  130  shakes along the normal line NL, the off-track may be reduced compared to the conventional head stack assembly regardless of the vibrations of the disk  107 . 
     The first hinge  123  may be biased toward the disk  107  to cause a first side of the head slider  130  closer to the center of the disk  107  to tilt closer to the disk surface than a second side of the head slider  130  opposite the first side. Since the first hinge  123  is thicker than the second hinge  124 , the first hinge  123  is also less flexible than the second hinge  124 , which causes the first side of the head slider  130  to remain tilted toward the surface of the disk  107 , even when the disk  107  and head stack assembly  110  vibrate. 
     As illustrated in  FIG. 6 . the second hinge  124  may be part of the connecting plate  115 , but it may he bent so that the portion of the second hinge  124  that contacts the suspension  120  is on an opposite surface of the suspension  120  than the first hinge  123 . The second hinge  124  may be biased away from a surface of the disk  107  to keep the first side of the head slider  130  tilted toward a surface of the disk  107 . Although  FIG. 6  illustrates the second hinge  124  having a first metal layer  125 . an insulation layer  126 . and a second metal layer  127 , the second hinge  124  may include only the first metal layer  125 . as illustrated in  FIG. 4 . 
       FIG. 7A  illustrates a computing unit  700  including a hard disk drive  100  according to an embodiment of the present general inventive concept. The computing unit  700  may include a controller  702  to control read and write operations of the hard disk drive and an interface  704  to direct the controller  702  to access the hard disk drive  100 . The interface  704  may include a data port such as a USB, Ethernet, Firewire, cable, telephone, or wireless data port, or any other port capable of transmitting data. The interface  704  may be connected to an external device  706  via the data port. 
     Alternatively, as shown in  FIG. 7B , the interface  704  may include a sensory interface, such as a display  708  to display data from the hard disk  100  or to display options to control the controller  704 . The interface  704  may also include a data input device such as a keypad  710  to allow a user to select options for reading from and/or writing to the hard disk drive  100 . Other user interfaces may include light indicators, LED&#39;s, audio output devices such as speakers, a keyboard, a button, a switch, or any other means to allow a user to interact with the computing device to access the hard disk drive. 
       FIGS. 8A and 8B  illustrate a relationship between the head slider  130 , the magnetic head  127 , and the disk  107 . As shown in  FIGS. 8A and 8B , a first side  801  of the magnetic head is closer to a center of the disk  107  than a second side  802 . When the magnetic head  127  is tilted, as in  FIG. 8B , the first side  801  is tilted towards the disk  107  and may be closer to the disk  107  than the second side  802 , which is tilted away from the disk  107 . 
       FIGS. 9A-10B  illustrate methods of manufacturing a head stack assembly  110 , and in particular a connecting plate  115  or the head stack assembly  110 .  FIG. 9A  illustrates forming a connecting plate  115  with a single metal layer. The connecting plate  115  includes first and second hinges  123 ,  124 . The first hinge  123  may be biased towards a disk direction by a bending process, for example. The first hinge  123  may also be treated to have a flexibility less than the flexibility of the second hinge  124 . For example, the first hinge  123  may be treated by heat, or by forming the first hinge  123  of less flexible materials than the second hinge  124 .  FIG. 9B  illustrates connecting the plate  115  to the swing arm  113  and the suspension  120 . The suspension  120  is connected to an end of the first and second hinges  123 ,  124 . 
       FIGS. 10A and 10B  illustrate the method of manufacturing the head stack assembly  110  illustrated in  FIG. 4 . The connecting plate  115  is formed by forming a first metal layer  125 , forming an insulation layer  126  on the first metal layer  125 , and forming a second metal layer  127  on the insulation layer  126 . Alternatively, the connecting plate  115  may be formed with additional layers or only two layers. As illustrated in  FIG. 10B , the second metal layer  127  and the insulation layer  126  are removed from the second hinge  124 . The layers  126 ,  127  may be removed by etching, for example. The connecting plate  115  may then be connected to the swing arm  113  and suspension  120  as illustrated in  FIG. 4 . The processes of adding layers to the connecting plate  115  and removing layers from the connection plate  115  may be performed either before or after the connecting plate  115  is connected to the swing arm  113  and/or the suspension  120 . 
     While the present general inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.