Abstract:
A disk apparatus includes a disk in which information is recorded, a carriage arm having a head slider provided at a tip thereof, the head slider moving over the disk during a read/write operation and being placed at an evacuated position outside an area of the disk during a halt of the disk apparatus, and a support base. An inertia latch mechanism slides on the support base from an original position to a latch position in response to an impacting force so as to latch the carriage arm when the disk apparatus is impacted, and slides on the support base from the latch position to the original position by disengaging from the carriage arm after dissipation of the impacting force. The support base and the inertia latch mechanism are in contact with each other through at least one raised portion that prevents a single surface-to-surface contact from being dominant between the support base and the inertia latch mechanism.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to disk apparatuses, and particularly relates to a disk apparatus provided with a carriage arm that has a head slider at the tip thereof and are supported by a chassis so as to be able to swing. 
     2. Description of the Related Art 
     Hard-drives that magnetically store information therein are typically used as built-in components inside computers. Notebook-type portable computers often suffer impact when they are accidentally hit or dropped. Hard-drives provided as built-in components inside the notebook-type computers are therefore required to have a structure that is more robust against impact than the hard-drives provided in desktop-type computers. 
     The hard-drives that are built-in components of notebook-type computers employ a ramp-load scheme in which a head slider is evacuated out of the disk space when the hard-drive comes to a halt, thereby improving an anti-impact performance. In addition, an inertia latch mechanism is employed that operates when relatively great impact is applied in a direction in which the carriage arm moves. The inertia latch latches the carriage arm so as to prevent the rotation thereof, thereby preventing the head slider from jumping on to the halted disk and sliding thereon to destroy data recorded in the disk. 
     The inertia latch mechanism needs to operate reliably when there is impact, and also needs to release the carriage arm reliably thereafter. If releasing is not complete, the carriage arm cannot swing when a load command is supplied, resulting in a malfunction of the hard-drive. 
     FIGS. 1A and 1B are illustrative drawings showing a related-art inertia latch mechanism that is provided in a hard-drive. A chassis base  10 , a cover  11 , and a latch arm  12  for latching a carriage arm are shown. The latch arm  12  has a bearing  12   a  thereof that engages in a fixed axis  13  standing on the chassis base  10 , so that the latch arm  12  can swing around the fixed axis  13 . 
     The latch arm  12  is attracted by a magnetic flux leaking from a magnetic circuit of the actuator so as to stay at a latch release position. When relatively great impact is applied, the latch arm  12  swings and reaches a latch position where it latches the carriage arm, thereby preventing the carriage arm from rotating. When an impact force dissipates, the latch arm  12  is attracted by the magnetic flux again to return to its original position. 
     The bearing  12   a  of the latch arm  12  has circular flat surfaces  12   a   1  and  12   a   2  on the lower and upper ends thereof, respectively. The circular flat surface  12   a   1  is placed upon a circular flat surface  13   a   1  of a flange portion  13   a  of the fixed axis  13 . In this manner, the bearing  12   a  of the latch arm  12  maintains a surface-to-surface contact with the flange portion  13   a  of the fixed axis  13 . The latch arm  12  swings by sliding, overcoming the resistance caused by friction of the surface contact. The circular flat surface  12   a   1  of the latch arm  12  and the circular flat surface  13   a   1  of the flange portion  13   a  have relatively large friction caused by the surface contact. This may undesirably prevent smooth rotation of the latch arm  12 . 
     If the rotation of the latch arm  12  returning to its original position after the dissipation of an impacting force is not complete, the releasing of the carriage arm by the latch ends up being incomplete. This results in the carriage arm failing to swing when a load command is supplied, thereby causing a malfunction of the hard-drive. 
     SUMMARY OF THE INVENTION 
     It is a general object of the present invention to provide a disk apparatus that substantially obviates one or more of the problems caused by the limitations and disadvantages of the related art. 
     Features and advantages of the present invention will be set forth in the description which follows, and in part will become apparent from the description and the accompanying drawings, or may be learned by practice of the invention according to the teachings provided in the description. Objects as well as other features and advantages of the present invention will be realized and attained by a disk apparatus particularly pointed out in the specification in such full, clear, concise, and exact terms as to enable a person having ordinary skill in the art to practice the invention. 
     To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a disk apparatus according to the present invention includes a disk in which information is recorded, a carriage arm having a head slider provided at a tip thereof, the head slider moving over the disk during a read/write operation and being placed at an evacuated position outside an area of the disk during a halt of the disk apparatus, a support base, and a inertia latch mechanism which slides on the support base from an original position to a latch position in response to an impacting force so as to latch the carriage arm when the disk apparatus is impacted, and slides on the support base from the latch position to the original position by disengaging from the carriage arm after dissipation of the impacting force, wherein the support base and the inertia latch mechanism are in contact with each other through at least one raised portion that prevents a single surface-to-surface contact from being dominant between the support base and the inertia latch mechanism. 
     The raised portion or portions prevent a single surface-to-surface contact from being dominant between the support base and the inertia latch mechanism by establishing a point contact, a line contact, or a plurality of discontinuous surface contacts, thereby reducing an area of contact between the inertia latch mechanism and the support base. This reduces slide friction, and facilitates smooth sliding movement, thereby improving the reliability of an inertia latch mechanism. 
     According to another aspect of the present invention, a disk apparatus includes a disk in which information is recorded, a carriage arm having a head slider provided at a tip thereof, the head slider moving over the disk during a read/write operation and being placed at an evacuated position outside an area of the disk during a halt of the disk apparatus, a magnetic circuit which drives the carriage arm, a support base, and a inertia latch mechanism which slides on the support base from an original position to a latch position in response to an impacting force so as to latch the carriage arm when the disk apparatus is impacted, and slides on the support base from the latch position to the original position in response to an attraction force by disengaging from the carriage arm after dissipation of the impacting force, the inertia latch mechanism including a portion thereof made of a synthetic resin mixed with metal particles that respond to magnetism generated by the magnetic circuit so as to generate the attraction force. 
     In the disk apparatus described above, a portion of the inertia latch mechanism is made of a synthetic resin mixed with metal particles, and can thus be molded into any desired shape and size with sufficient accuracy. Use of this portion makes it possible to arrange mechanical parts accurately, so that a gap between this portion and the magnetic circuit can be made small, thereby increasing the force by which the magnetic circuit attracts the inertia latch mechanism. 
     Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are illustrative drawings showing a related-art inertia latch mechanism that is provided in a hard-drive; 
     FIGS. 2A and 2B are illustrative drawings showing a hard-drive according to an embodiment of the present invention; 
     FIG. 3 is an illustrative drawing showing an inertia latch mechanism of the present invention; 
     FIG. 4 is a cross-sectional view of the inertia latch mechanism taken along a line IV—IV in FIG. 2A; 
     FIGS. 5A through 5C are illustrative drawings showing the operation of the inertia latch mechanism when the hard-drive is impacted; 
     FIGS. 6 and 6B are illustrative drawings showing the operation of the inertia latch mechanism after dissipation of an impacting force; 
     FIGS. 7A and 7B are illustrative drawings showing a first variation of a bearing; 
     FIGS. 8A and 8B are illustrative drawings showing a second variation of the bearing; 
     FIGS. 9A and 9B are illustrative drawings showing a third variation of the bearing; 
     FIGS. 10A through 10C are illustrative drawings showing a variation of an axis member and a cover; 
     FIG. 11 is an illustrative drawing showing a variation of a latch arm; and 
     FIGS. 12A and 12B are illustrative drawings showing an inertia latch mechanism in operation where the variation of the latch arm is used. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, embodiments of the present invention will be described with reference to the accompanying drawings. 
     FIGS. 2A and 2B are illustrative drawings showing a 2.5-inch hard-drive  20  according to an embodiment of the present invention. This hard-drive is provided as a built-in component in a notebook-type computer. FIG. 2A shows the hard-drive  20  with a cover thereof removed. FIG. 2B shows a cross-sectional view of the hard-drive  20  taken along the line B—B in FIG.  2 A. X 1 -X 2  indicates a longitudinal direction, and Y 1 -Y 2  indicates a transverse direction, with Z 1 -Z 2  representing a direction along the height. 
     The hard-drive  20  includes a chassis base  21  having a shallow concave portion, a spindle motor  22  on the chassis base  21 , two disks  23  having a diameter of 2.5 inches and fixed to the rotor of the spindle motor  22 , a carriage arm  26  supported in such a manner as to swing around an axis  25  provided on the chassis base  21 , a head slider  27  provided at the tip of the carriage arm  26 , an actuator  28  provided on the upper surface of the chassis base  21  and having a voice-coil-motor configuration to swing the carriage arm  26  back and fourth, a ramp member  39  fixedly mounted to the chassis base  21 , and an inertia latch mechanism  29  provided on the upper surface of the chassis base  21 . The chassis base  21  and a upper cover  30  together make a disk enclosure  31 , which is a sealed space. The disks  23  are contained in the disk enclosure  31 . The actuator  28  includes a lower yolk  35 , a magnet  36  fixedly mounted on the yolk  35 , an upper yolk  37  covering the magnet  36 , and a coil  38  having substantially a rectangular shape and provided as an integral portion of a base part  26   a  of the carriage arm  26 . The yolk  35 , the magnet  36 , and the yolk  37  together constitute a magnetic circuit. The head slider  27  has a magnetic head on an end surface thereof. 
     The hard-drive  20  is used as a built-in component of notebook-type personal computers, and receives electric power from a buttery to operate. The operation will be described as follows. 
     The disks  23  is rotated at a few thousands rpm in a direction A by the spindle motor  22 . The actuator  28  swings the carriage arm  26  in a direction B 1 -B 2 , so that the head slider  27  moves in a radial direction over the upper surface of the disks  23  by flying in the air. This makes it possible to scan a truck to be scanned, thereby allowing the magnetic head to perform the writing/reading of information. 
     When an unload command is supplied from the notebook-type personal computer, the carriage arm  26  swings in the direction towards B 1  so as to be placed at an evacuation position as shown in FIG.  2 A. The tip of the carriage arm  26  is supported by the ramp member  39 , so that the head slider  27  is in an evacuated state, being out of the area of disks  23 . Further, the spindle motor  22  halts operation thereof, thereby putting the hard-drive  20  in a suspension mode. 
     If a load command is supplied during the suspension mode, the spindle motor  22  starts rotating and the actuator  28  starts being driven. As a result, the carriage arm  26  is swung in the B 2  direction, and is released from the ramp member  39 , so that the head slider  27  is loaded onto the disks  23  that are rotating. The head slider  27  flies in the air over the surface of the disks  23 , thereby attending to the writing and reading of information. 
     In the following, the inertia latch mechanism  29  will be described. 
     FIG. 3 is an illustrative drawing showing the inertia latch mechanism  29 . The inertia latch mechanism  29  includes an inertia balancing arm  50  and a latch arm  51  serving as a latch member. The latch arm  51  latches the carriage arm  26 . The inertia balancing arm  50  stays at the same position when impact is given to the hard-drive  20  in such a direction as to swing the carriage arm  26 , i.e., when the impact is given in the direction parallel to the X-Y plane in which the chassis base  21  extends. As a result, the latch arm  51  that moves together with the chassis base  21  is swung around an axis member  80 . 
     The basis portion  26   a  of the carriage arm  26  has a horn portion  26   b  that projects substantially in the X 2  direction in FIG.  2 A. The latch arm  51  engages in the horn portion  26   b.    
     As shown in FIG. 3, the latch arm  51  is a molded product made of synthetic resin, and includes a bearing  60 , an arm  61  extending from the bearing  60  in one direction, an arm  62  extending from the bearing  60  in the opposite direction, a protrusion  61 a projecting in the Z 2  direction at the tip of the arm  61 , a protrusion  62   a  projecting in the Z 1  direction at the tip of the arm  62 , and a protrusion  62   b  projecting in the Z 1  direction at the base of the arm  62 . The protrusion  62   b  at the base of the arm  62  has a U-shape steel member  63  engaged therein. 
     The end of the bearing  60  on the Z 2  side has a protrusion  60   a  projecting in the Z 2  direction with a cross-sectional profile being a semicircle of a radius r 1  and having a ring shape as shown in FIG.  4 . 
     The end of the bearing  60  on the Z 1  side has a protrusion  60   b  projecting in the Z 1  direction with a cross-sectional profile being a semicircle of a radius r 2  and having a ring shape as shown in FIG.  4 . 
     The latch arm  51  is supported such as to be able to swing around the axis member  80  having the flange portion  80   a  where the axis member  80  sticks out from the chassis base  21  with a base thereof being buried therein as shown in FIG.  2 A and FIG.  4 . When the latch arm  51  swings counterclockwise to approach the actuator  28 , the arm  61  comes into a trajectory  90  along which the horn portion  26   b  moves when the carriage arm  26  swings counterclockwise. 
     As shown in FIG. 3, the inertia balancing arm  50  includes an elongated arm body  70 , a bearing  71  made of synthetic resin and forming an integral part of the arm body  70  near the end thereof facing the Y 2  direction, a weight  72  fixed to the bottom surface of the arm body  70  at the end thereof facing the Y 2  direction, and pins  73  and  74  fixedly attached to the Y 1  end of the arm body  70  and at some distance from the Y 1  end, respectively. The inertia balancing arm  50  has a size and shape that are balanced around the bearing  71  with respect to swinging movement, and has a relatively large inertia moment. 
     The Z 2  end of the bearing  71  has a protrusion  71   a  projecting in the Z 2  direction with a cross-sectional profile being a semicircle of a radius r 3  and having a ring shape as shown in FIG.  4 . 
     The Z 1  end of the bearing  71  has a protrusion  71   b  projecting in the Z 1  direction with a cross-sectional profile being a semicircle of a radius r 4  and having a ring shape as shown in FIG.  4 . 
     As shown in FIG.  2 A and FIG. 4, the inertia balancing arm  50  is supported to swing around an axis member  81  having a flange portion  81   a  that sticks out from the chassis base  21  with a base portion thereof buried therein. The inertia balancing arm  50  is positioned close to the actuator  28 . The plane in which the inertia balancing arm  50  swings is the same X-Y plane in which the carriage arm  26  swings. 
     In the following, the operation of the inertia latch mechanism  29  will be described. 
     The inertia latch mechanism  29  operates when the impact on the hard-drive  20  is given in such a direction to swing the carriage arm  26  counterclockwise during the suspension mode of the hard-drive  20  shown in FIG.  2 A. 
     When the hard-drive  20  is in the suspension mode, the inertia latch mechanism  29  is positioned as shown in FIG.  2 A and FIG.  5 A. The latch arm  51  is urged clockwise as the steel member  63  is attracted by the magnetic flux leaking from the magnetic circuit of the actuator  28 , so that the protrusion  61   a  comes into contact with a step  21   a  of the chassis base  21 , and the latch arm  51  is restricted from swinging further. The arm  61  is situated outside the trajectory  90 . The pin  74  of the inertia balancing arm  50  is in contact with the X 2 -side lateral surface of the arm  61 . A portion close to the Y 1  end of the arm body  70  crosses the arm  62 , and the pin  73  faces the X 1 -side lateral surface of the arm  62 . 
     When impact is given to the hard-drive  20  in the X-Y plane to prompt a swing movement counterclockwise, the carriage arm  26  tries to swing counterclockwise from the position shown in FIG.  2 A and FIG.  5 A. 
     As shown in FIG. 5B, however, the inertia balancing arm  50  tries to stay in its original position because of its own inertia, so that latch arm  51  is swung counterclockwise by the pin  74 , resulting in the arm  61  coming into the trajectory  90 . The carriage arm  26  having started swinging counterclockwise is latched when the horn portion  26   b  engages in the protrusion  61   a  of the arm  61  as shown in FIG. 5C, and, thereafter, a further swinging movement is stopped. AS a result, the head slider does not jump on to the halted disks  23  to destroy data recorded in the disks  23 . 
     After the impacting force dissipates, the steel member  63  is attracted by the magnetic flux leaking from the magnetic circuit of the actuator  28 , resulting in the latch arm  51  swinging clockwise, with the associated movement of the inertia balancing arm  50  swinging counterclockwise, as shown in FIG.  6 A. In the end, the inertia latch mechanism  29  will return to its original position as shown in FIG.  6 B. As the latch arm  51  swings, the latching of the horn portion  26   b  is disengaged, and the arm  61  moves out of the trajectory  90 , with a resulting state in which the carriage arm  26  can swing clockwise. 
     The protrusion  60   a  of the latch arm  51  is in contact with the flange portion  80   a  of the axis member  80 , so that a circular line contact  100  as shown in FIG. 4 is provided. In the same manner, the protrusion  71   a  of the inertia balancing arm  50  is in contact with the flange portion  81   a  of the axis member  81 , so that a circular line contact  101  is provided. 
     When the inertia latch mechanism  29  returns from the state of FIG. 5C to the state of FIG. 6B via the state of FIG. 6A after the dissipation of impact, the latch arm  51  swings by sliding, overcoming the friction caused by the circular line contact between the protrusion  60   a  and the flange portion  80   a . This slide friction is smaller than the slide friction that is caused by the surface-to-surface contact as shown in the related-art configuration of FIG.  1 . Further, the inertia balancing arm  50  swings by sliding, overcoming the friction caused by the circular line contact between the protrusion  71   a  and the flange portion  81   a . This slide friction is smaller than the slide friction that is caused by the surface-to-surface contact. With this provision, therefore, sliding of the latch arm  51  and the inertia balancing arm  50  is smoothly made, so that the inertia latch mechanism  29  can return from the state of FIG. 5C to the state of FIG. 6B via the state of FIG. 6A without failure. Accordingly, the carriage arm  26  swings in response to a load command, insuring a reliable operation of the hard-drive  20 . 
     Further, since the cross-sectional profile of the protrusions  61   a  and  71   a  is a semicircular shape rather than a triangular shape, wearing does not take place as much, thereby producing little dust generated by wearing. 
     If the inertia balancing arm  50  is positioned upside down, the latch arm  51  has the protrusion  60   b  thereof in contact with the interior surface of the cover  30 , so that a circular line contact  110  is established. By the same token, the inertia balancing arm  50  has the protrusion  71   b  thereof in contact with the interior surface of the cover  30 , thereby providing a circular line contact  111 . Accordingly, the latch arm  51  and the inertia balancing arm  50  are subjected to friction that is smaller than that of a surface-to-surface contact. Sliding of the latch arm  51  and the inertia balancing arm  50  can thus be smoothly made, thereby insuring that the inertia latch mechanism  29  returns from the state of FIG. 5C to the state of FIG. 6B via the state of FIG.  6 A. 
     The configuration of the present invention that reduces the friction of sliding movement is applicable to a case in which a member for latching the carriage arm  26  travels along a straight line rather than swinging around a given axis. 
     In the following, variations of bearings of the latch arm  51  and the inertia balancing arm  50  will be described. 
     FIGS. 7A and 7B are illustrative drawings showing a first variation of the bearing. FIG. 7A shows a bearing  120 , which provides a discontinuous line contact. The bearing  120  includes protrusions  121   a ,  121   b , and  121   c , which are not continuous with each other. The protrusions  121   a ,  121   b , and  121   c  have a cross-sectional profile of a semicircular shape, and form arcs arranged at equal intervals along the circumference. This bearing  120  comes in contact with the flange portion  80   a  on arcs  122   a ,  122   b ,  122   c  as shown in FIG. 7B, which provide discontinuous line contact. The friction of the bearing  120  sliding on the flange portion  80   a  is reduced compared with that of a surface-to-surface contact. 
     FIGS. 8A and 8B are illustrative drawings showing a second variation of the bearing. FIG. 8A shows a bearing  130 , which provides point contacts. The bearing  130  includes hemispheres  131   a ,  131   b , and  131   c  arranged at equal intervals along the perimeter. The bearing  130  comes in contact with the flange portion  80   a  on points  132   a ,  132   b ,  132   c  as shown in FIG. 8B, which provide point contacts. The friction of the bearing  130  sliding on the flange portion  80   a  is reduced compared with that of a surface-to-surface contact. 
     FIGS. 9A and 9B are illustrative drawings showing a third variation of the bearing. FIG. 9A shows a bearing  140  that includes arc surface portions  142   a ,  142   b , and  142   c  having flat top surfaces, which are separated by recesses  141  arranged at equal intervals on the rim. The arc surface portions  142   a ,  142   b , and  142   c  are discontinuous with each other. The bearing  140  comes in contact with the flange portion  80   a  on discontinuous surfaces  143   a ,  143   b ,  143   c  as shown in FIG.  9 B. The friction of the bearing  140  sliding on the flange portion  80   a  is reduced compared with that of a surface-to-surface contact. 
     In the following, a variation of the cover and the axis member that supports the latch arm will be described with reference to FIGS. 10A through 10C. 
     This variation is directed to a configuration that provides line contact by forming protrusions on the axis member and the cover. 
     As shown in FIGS. 10A,  10 B, and  10 C, the bearing  12   a  of the latch arm  12  has the circular flat surfaces  12   a   1  and  12   a   2  at the bottom end and at the top end, respectively. 
     As shown in FIGS. 10B and 10C, an axis member  80 A provided with a flange portion  80 Aa has a protrusion  80 Aa 1  formed on the flange portion  80 Aa where the protrusion  80 Aa 1  has a ring shape and a cross-sectional profile of a semicircular shape projecting in the Z 1  direction. The circular flat surface  12   a   2  of the bearing  12   a  of the latch arm  12  is in contact with the ring-shape protrusion  80 Aa 1 , thereby establishing line contact. In this case, friction of the bearing  12   a  sliding on the flange portion  80 Aa is reduced compared with that of a surface-to-surface contact. 
     As shown in FIGS. 10A and 10B, a cover  30 A has a ring-shape protrusion  30 Aa formed at a position facing the bearing  12   a  where the ring-shape protrusion  30 Aa has a cross-sectional profile of a semicircle projecting in the Z 2  direction. 
     If the hard-drive is situated upside down, the circular flat surface  12   a   1  of the bearing  12   a  of the latch arm  12  comes in contact with the ring-shape protrusion  30 Aa, thereby establishing a line contact. In this case, friction of the bearing  12   a  sliding on the cover  30 A is reduced compared with that of a surface-to-surface contact. 
     In what follows, a variation of the latch arm will be described with reference to FIG.  11 . 
     A latch arm  51 A of FIG. 11 is configured such that an increased attracting force is effected clockwise when the latch arm  51 A is attracted by the magnetic flux leaking from the actuator  28 . 
     The latch arm  51 A has substantially the same configuration as the latch arm  51  as shown in FIG. 3, and counterpart components are designated by the same reference numerals with a suffix “A”. The latch arm  51  is a two-part molded product. A portion excluding a protrusion  62 Ab is made by molding synthetic resin first, and, then, the protrusion  62 Ab shown by shading is made by molding a synthetic resin mixed with metal particles that exhibit magnetism. No U-shape steel member  63  as shown in FIG. 3 is employed in this configuration. 
     Since the protrusion  62 Ab is molded in the cast, it is possible to form any shape, which provides greater latitude than use of an engaged structure of the steel member  63 . Also, this provides a basis for improving the precision of shape and size. In the normal and routine position as shown in FIG. 12A, therefore, a gap g 10  between the protrusion  62 Ab and the actuator  28  can be set narrower than a gap g 1  shown in FIG.  5 A. In proportion, a gap g 11  as shown in FIG. 12B between the protrusion  62 Ab and the actuator  28  observed when the inertia latch mechanism  29  is in operation upon impact is narrower than a gap g 2  shown in FIG.  5 C. As a result, the magnetic flux leaking from the actuator  28  attracts the latch arm  51 A clockwise with a stronger force than in the case of FIG. 3 in which the latch arm  51  is used. 
     Accordingly, the latch arm  51 A swings and returns to its original position as shown in FIG. 12A after the dissipation of an impacting force. 
     Further, the present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention. 
     The present application is based on Japanese priority application No. 2001-343655 filed on Nov. 8, 2001, with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.