Disk drive including a latch configured to lock an actuator in response to an external force

A disk drive. The disk drive includes: a head for accessing a data recording area of a disk; an actuator for pivoting to move the head; a voice coil motor; and, a latch configured to lock the actuator from pivoting toward the data recording area in response to an external force. The voice-coil motor includes a voice coil, a magnet, and a yoke. The latch is positioned at a closed position when the actuator is positioned at a stand-by position, and is configured to pivot by application of a magnetic bias force with pivoting of the actuator from the stand-by position into proximity with the data recording area such that the latch is configured to stop at an open position. The yoke includes a protrusion which protrudes toward the magnetic body at the open position.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from the Japanese Patent Application No. 2008-315114, filed Dec. 10, 2008, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

Embodiments of the present invention relate to a disk drive including a latch mechanism for locking an actuator which pivots by an external force in the disk drive.

BACKGROUND

In a hard disk drive (HDD), which is an example of a disk drive, a magnetic-recording head held by an actuator is positioned to a given track on a spinning magnetic-recording disk to read and write data. On the magnetic-recording disk, a data area where data are to be recorded is defined. At the shut-down of the HDD in a given utilization period, the magnetic-recording head is moved to a predetermined stand-by position outside the data area by the actuator, and is retained at the stand-by position during non-operation of the HDD to protect data on the data area.

If an HDD receives any impact from an external force during non-operation, the actuator may pivot by the impact so that the magnetic-recording head may return to the data area. At this time, the magnetic-recording head may destroy data. Therefore, HDDs have latch mechanisms for locking actuators to retain the actuators outside the data area, as is known in the art. Moreover, as representative latch mechanisms, magnetic latches and mechanical latches are known in the art.

Engineers and scientists engaged in HDD manufacturing and development are interested in the design of HDDs that employ latch mechanisms to preserve data integrity on the magnetic-recording disk to meet the rising demands of the marketplace for increased performance, and reliability.

SUMMARY

Embodiments of the present invention include a disk drive. The disk drive includes: a head for accessing a data recording area of a disk; an actuator for supporting the head and for pivoting to move the head; a voice coil motor; and, a latch configured to lock the actuator from pivoting on a pivot shaft toward the data recording area in response to an external force. The voice-coil motor includes a voice coil, a magnet, and a yoke. The yoke is disposed so as to overlap with the voice coil attached to the actuator in a direction parallel to the pivot axis of the actuator such that the yoke is configured to move the actuator in response to an electrical current flowing through the voice coil interacting with a magnetic field of the magnet. The latch is positioned at a closed position while being supported by a portion of the actuator when the actuator is positioned at a stand-by position, and is configured to pivot by application of a magnetic bias force which is induced by magnetic flux leakage from the voice coil motor such that the magnetic bias force magnetic bias force is configured to act on a magnetic body of the latch with pivoting of the actuator from the stand-by position into proximity with the data recording area such that the latch is configured to stop at an open position. The yoke includes a protrusion which protrudes toward the magnetic body at the open position and is located at a lower position than the magnetic body. The protrusion includes a tip increasing in height in the direction in which the magnetic body is configured to move toward the open position.

DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to the alternative embodiments of the present invention. While the invention will be described in conjunction with the alternative embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.

Furthermore, in the following description of embodiments of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it should be noted that embodiments of the present invention may be practiced without these specific details. In other instances, well known methods, procedures, and components have not been described in detail as not to unnecessarily obscure embodiments of the present invention. Throughout the drawings, like components are denoted by like reference numerals, and repetitive descriptions are omitted for clarity of explanation if not necessary.

Description of Embodiments of the Present Invention for a Disk Drive Including a Latch Configured to Lock an Actuator in Response to an External Force

With relevance to embodiments of the present invention, a typical magnetic latch includes a mechanism for holding an actuator by a magnet embedded in a rubber portion attracting an iron slug attached to the distal end of the actuator. Sufficient magnetic force is provided to the magnetic latch to continue attracting the actuator so as to hold the actuator in the event of an impact. On the other hand, to reduce the amount of materials used, the magnet in a voice coil motor (VCM) may be reduced in size.

The smaller the magnet, the less the torque constant in the VCM. Thus, an HDD with a smaller VCM torque constant may not be able to exert sufficient torque for pulling the actuator away from the magnetic latch at the start-up of the HDD. On the other hand, if the attracting force is reduced so that the attracting force is no longer adequate to pull the actuator away from the magnetic latch, an issue may arise that the actuator cannot be held against an impact.

Mechanical latches lock actuators mechanically, so the functions are not affected by VCM magnets like the magnetic latches. Two-piece mechanical latches are known in the art as typical mechanical latches. A two-piece mechanical latch includes a mechanism in which a long lever and a short bar are combined and can cope with both clockwise and counterclockwise external impacts. The long lever pivots by an inertial force induced by an external force; and, the short bar engaged with the long lever opens and closes with the motion of the long lever to lock the actuator.

In the two-piece mechanical latch, however, when an HDD is vibrating, the long lever may start vibrating exacerbating the vibration of the HDD. Moreover, for free pivotal movement of the long lever and because of a small mounting space for the long lever, a common long lever is not fixed in the axial direction but has an amount of play, which may cause large vibration. Such vibration of the mechanical latch may induce vibration of the actuator or the magnetic-recording head to cause an error in the HDD.

One-piece mechanical latches, which are referred to herein by the term of art, “single latches,” can reduce the above-described issue of vibration in two-piece mechanical latches. A single latch may include a hook for engaging with the actuator; and, the one-piece structure that includes the hook pivots the actuator by magnetic force, or inertial force to open the single latch, or close the single latch, which in turn locks the actuator from pivoting in response to application of an external force, which is a force applied to the disk drive from outside, or external to, the disk drive, as is known in the art. Since a single latch does not have a component equivalent to the long lever, the single latch can suppress occurrence of vibration harmful to head positioning, even if the HDD is vibrating.

A typical single latch is closed when the actuator is at a stand-by position, locking the actuator which has a tendency to pivot toward the magnetic-recording disk because of an external impact. A torque in the direction to open the latch is constantly applied to the single latch by magnetic flux leakage from a VCM and a magnetic pin mounted on the single latch. In loading the actuator onto the magnetic-recording disk, as the actuator pivots, the single latch pivots together with the actuator because of the torque, turning from a closed state to an opened state.

To lock the actuator against various impacts from the external environment, a long time is provided for the single latch to be positioned where the single latch is able to lock the actuator. Reducing XY torque to act in the direction to open the single latch by magnetic flux leakage allows extending the time for the latch closure.

On the other hand, vibration in the pivot axis direction, which is the Z direction, may be suppressed even with a single latch. While the actuator is positioned in proximity with the magnetic-recording disk, vibration of the single latch is minimized to reduce the effect on head positioning. To suppress the Z-direction vibration of the open single latch, enhancement of a Z-direction attracting force caused by magnetic flux leakage from the VCM has useful effects on latch performance.

The force caused by the magnetic flux leakage from the VCM acts on a magnetic pin attached to the single latch. Changing the size and position of this magnetic pin provides a stronger Z-direction attracting force, but simultaneously, causes a stronger XY torque. To increase the vibration proof characteristics without degrading the latch function for locking the actuator, embodiments of the present invention reinforce the Z-direction attracting force without increasing the XY torque to act on the single latch.

In accordance with embodiments of the present invention, a disk drive includes a head for accessing a data recording area of a disk, an actuator for supporting the head and pivoting to move the head, a voice coil motor, and a latch configured to lock the actuator from pivoting on a pivot shaft toward the data recording area in response to an external force. In accordance with embodiments of the present invention, the voice-coil motor includes a voice coil, a magnet, and a yoke. In accordance with embodiments of the present invention, the yoke is disposed so as to overlap with the voice coil attached to the actuator in a direction parallel to the pivot axis of the actuator such that the yoke is configured to move the actuator in response to an electrical current flowing through the voice coil interacting with a magnetic field of the magnet. In accordance with embodiments of the present invention, the latch is positioned at a closed position while being supported by a portion of the actuator when the actuator is positioned at a stand-by position. In accordance with embodiments of the present invention, the latch is configured to pivot by application of a magnetic bias force which is induced by magnetic flux leakage from the VCM such that the magnetic bias force magnetic bias force is configured to act on a magnetic body of the latch with the pivot of the actuator from the stand-by position to above the data recording area such that the latch is configured to stop at an open position. In accordance with embodiments of the present invention, the yoke includes a protrusion which protrudes toward the magnetic body at the open position and is located at a lower position than the magnetic body. In accordance with embodiments of the present invention, the protrusion includes a tip increasing in height in the direction in which the magnetic body is configured to move toward the open position. Thus, in accordance with embodiments of the present invention, the protrusion having the above-described structure can prevent vibration of the latch while suppressing adverse effects on the latching capability of the latch for locking the latch.

In one embodiment of the present invention, the tip of the protrusion includes an end face of a slant increasing in height in the direction in which the magnetic body is configured to move toward the open position. Thus, in an embodiment of the present invention, vibration of the latch can be prevented while effectively suppressing adverse effects on the latching capability. Moreover, in an embodiment of the present invention, the protrusion includes an arm extending from a plate of the yoke toward the latch and a tab bent upward from the arm such that an end face of the tab is the end face of the slant. Thus, in an embodiment of the present invention, the position and angle of the end face can be easily set to a designated state.

In one embodiment of the present invention, the slant angle of the end face of the slant ranges from 30° to 45°. Thus, in an embodiment of the present invention, vibration of the latch can be prevented while effectively suppressing adverse effects on the latching capability. In an embodiment of the present invention, the normal to the slant is disposed toward a tangential direction to a path of the magnetic body at the open position. Thus, in an embodiment of the present invention, adverse effects on the latching capability can be reduced further.

In another embodiment of the present invention, the tip of the protrusion includes an apex at a highest position. Thus, in an embodiment of the present invention, vibration of the latch can be prevented while effectively suppressing adverse effects on the latching capability.

In another embodiment of the present invention, the tip of the protrusion includes a first-tier face and a second-tier face which is located next to the first-tier face in the direction of movement of the magnetic body toward the open position and is disposed at a higher position than the first-tier face. In another embodiment of the present invention, the protrusion includes an arm extending from a plate of the yoke toward the latch and a tab bent upward from the arm such that the end face of the tab includes the first-tier face and the second-tier face. Alternatively, in another embodiment of the present invention, the protrusion includes a horizontally extending arm and a pin standing on the top surface of the arm at a location away from the end of the arm such that the end of the top face of the arm is the first-tier face and the top face of the pin is the second-tier face. Thus, in an embodiment of the present invention, vibration of the latch can be prevented while effectively suppressing adverse effects on the latching capability.

Embodiments of the present invention provide suppression of vibration of a single latch for locking an actuator while suppressing an adverse effect on the latching capability of the single latch. In accordance with embodiments of the present invention, a HDD is subsequently described as an example of a disk drive, by way of example without limitation thereto. In accordance with embodiments of the present invention, the HDD includes a mechanical latch for locking an actuator from pivoting due to an inertial force induced by an external force. In an embodiment of the present invention, the mechanical latch is a one-piece mechanical latch that is a single latch. In an embodiment of the present invention, the single latch stops the pivotal movement of an actuator from pivoting toward a data area due to an inertial force induced by an external force to lock the actuator. In another embodiment of the present invention, a structure is provided in which a magnetic bias force is applied to a magnetic substance in the single latch. In an embodiment of the present invention, a yoke, which the VCM includes as a component portion, for the actuator includes a protrusion whose tip has a specific shape. In an embodiment of the present invention, this structure can suppress vibration of the latch while suppressing an adverse effect on the latching capability of the single latch. In accordance with embodiments of the present invention, before proceeding to describe in detail the structure of the single latch and the yoke for applying a magnetic bias force to the single latch, the configuration of a HDD within which the single latch is mounted is next described.

With reference now toFIG. 1, in accordance with an embodiment of the present invention, a plan view is shown that schematically depicts a configuration of HDD1with a mechanical latch18mounted within HDD1. A base10of a disk enclosure (DE) is secured with a top cover (not shown), and houses components of HDD1in the DE. A spindle motor (SPM)13spins a magnetic-recording disk11at a specific angular rate. The magnetic-recording disk11, an example of a disk for storing data, is attached to a rotatable spindle shaft for SPM13. A head-slider12, an example of a head, includes a slider and write and read elements of a magnetic-recording head attached to the slider.

An actuator14is pivotally held by a pivot shaft15and is driven by a VCM16. The actuator14holds the head-slider12and pivots on the pivot shaft15to move the head-slider12. The actuator14includes components of a suspension141, an arm142which supports the suspension141and includes a bore for receiving the pivot shaft15, a coil support143, and a flat coil144on the inner peripheral side of the coil support143, which are connected in this order from the distal end of the actuator14where the head-slider12is disposed. The VCM16includes the flat coil144and two magnets (not shown inFIG. 1) disposed so as to sandwich the flat coil144between the two magnets with space allowed for the rotary motion of the actuator14, to which the flat coil144is attached, upon passage of an electrical current through the flat coil144. The VCM includes a voice coil, which is the flat coil144, at least one magnet, and a yoke. The yoke is disposed so as to overlap with the voice coil, which is the flat coil144, attached to the actuator14in a direction parallel to the pivot axis of the actuator14such that the yoke is configured to move the actuator14in response to an electrical current flowing through the voice coil, which is the flat coil144, interacting with a magnetic field of the magnet, or magnets.FIG. 1shows an upper yoke161for holding the upper magnet. In this regard, however, only one magnet may be disposed on either a lower or an upper side.

As exemplified inFIG. 1, the actuator14moves the head-slider12over the data area of the spinning magnetic-recording disk11to allow the head-slider12to access the data recording area. As used herein, “access” is a term of art that refers to operations in seeking a data track of a magnetic-recording disk11and positioning a magnetic-recording head on the data track for both reading data from, and writing data to, a magnetic-recording disk11. Pivotal movement of the actuator14allows the head-slider12to move along a nominally radial direction of the surface of the magnetic-recording disk11. Typically, the head-slider12flies in proximity to the magnetic-recording disk11.

A ramp17is disposed at the outer periphery of the magnetic-recording disk11, along side of the magnetic-recording disk11. When HDD1does not access data that is when HDD1does not read data or write data, such as during non-operation or in an idling state, the actuator14is at a stand-by position on the ramp17. In unloading the head-slider12, the actuator14pivots away from being in proximity with the data area of the magnetic-recording disk11toward the ramp17, which is clockwise inFIG. 1; a tab145at the distal end of the actuator14slides and moves over the ramp17; and, the actuator14stops at the stand-by position. At this time, the head-slider12is positioned away from the magnetic-recording disk11. In loading, the actuator14pivots in the direction reverse from the one in unloading to move the head-slider12into proximity with the data area of the magnetic-recording disk11.

When the actuator14is at the stand-by position and HDD1receives an impact from an external force, the actuator14may pivot by an inertial force so that the actuator14and the head-slider12may move into proximity with the data area of the magnetic-recording disk11. If the actuator14is suddenly loaded from the ramp17, the head-slider12vibrates severely. Then, the data in the data area, the head-slider12, or the suspension141is more likely to be damaged. A single latch18, which is referred to herein as a latch, latches the actuator14from pivotal movement, so that the head-slider12or the suspension141will not move into proximity with the data area of the magnetic-recording disk11because of the external force.

With reference now toFIGS. 2(a) and2(b), in accordance with an embodiment of the present invention, a plan view is shown inFIG. 2(a) that schematically depicts an actuator14brought into proximity with the magnetic-recording disk11and the latch18still in an open state; and, inFIG. 2(b), a plan view is shown that schematically depicts an actuator14parking at the stand-by position on the ramp17and the latch18still in a closed state. The latch18pivots on a pivot shaft181. As shown inFIG. 2(a), when the actuator14is brought into proximity with the magnetic-recording disk11, the latch18is open. In contrast, when the actuator14is positioned at the stand-by position, the latch18is closed as shown inFIG. 2(b). The closed latch18when the actuator14stays at the stand-by position enables the latch18to lock the actuator14more securely when an external impact is applied.

When the latch18is on the path of the actuator14, the latch18is in a closed state; and when the latch18is off the path, the latch18is in an open state. Accordingly, while the actuator pivots from the stand-by position into proximity with the magnetic-recording disk, the latch18pivots; and in the course of the pivotal movement, the latch18is switched from the closed state into the open state. When the actuator14is parking at the stand-by position, the position, which is a state, of the latch18which is still in the closed state is referred to by the term of art, “stand-by closed position,” which is a state of the latch18. When the actuator14is in proximity with the data area of the magnetic-recording disk, the position, which is a state, of the latch18which is still in the open state is referred to by the term of art, “still open position,” which is a state of the latch18.

When the actuator14, to which the head-slider12is attached, is unloaded from being in proximity with the magnetic-recording disk to the stand-by position (moved from the position shown inFIG. 2(a) to that shown inFIG. 2(b)), the edge on the magnetic-recording disk11side of the coil support143makes contact with and pushes a bar182of the latch18. The actuator14pivoting clockwise pushes the latch18to pivot counterclockwise, causing the latch18in the still open state to turn into the stand-by closed state.

With reference now toFIGS. 3(a),3(b),3(c) and3(d), in accordance with an embodiment of the present invention, perspective views are shown that illustrate the structure of the latch18.FIGS. 3(a) and3(c) illustrate the structure of the latch18on the opposite side to the inner wall of the base.FIGS. 3(b) and3(d) illustrate the structure of the latch18on the opposite side to the actuator14. InFIGS. 3(a) and3(b), the lower side of each figure corresponds to the bottom side of the base10and the upper side corresponds to the top cover side. InFIGS. 3(c) and3(c), the upper side of each figure corresponds to the bottom side of the base10and the lower side corresponds to the top cover side.

The latch18is a one-piece mechanical latch and includes: a bar182, a body183, an arm184, a latch hook185, a counter weight186, and a pin187made of a magnetic substance. The components except for the pin187form a one-piece structure, which is typically formed by integrally molding a resin such as polyacetal. A bore188is formed in the body183to receive the pivot shaft181for the latch18.

The bar182for contacting the coil support143in unloading, which was described referring toFIGS. 2(a) and2(b), includes an arm821protruding from the body183toward the actuator14and a tab822extending vertically downward from the arm, where the reference numerals are shown inFIG. 3(b). Specifically, the coil support143makes contact with the tab822of the bar182. Since the contact surface of the tab822to the coil support143is curved, even if pivotal movement of the actuator14displaces the contact point to the coil support143, proper contact can be achieved at any position.

The arm184extends from the body183in a direction vertical to the pivot shaft181and a latch hook185is formed at the end of the arm184, extending vertically downward. The latch hook185engages with the hook146of the actuator14to lock the actuator14which pivots toward the magnetic-recording disk11when an external force is applied to HDD1. As shown inFIGS. 2(a) and2(b), the actuator hook146is formed on the coil support143. More specifically, the actuator hook146is located at the rear end on the magnetic-recording disk11side of the coil support143. The pivot shaft15for the actuator14is located between the head-slider12and the actuator hook146.

The latch hook185and the tab822of the bar182are formed to have a specific angle around the bore188for the pivot shaft. The counter weight186is formed at the opposite side of the latch hook185across the pivot shaft181and places the center of gravity of the entire latch18within the diameter of the bore188for the pivot shaft.

A pin187is inset near the bar182. The pin187is a magnetic substance such as iron, nickel, or an alloy of iron and nickel, and is attracted by the magnetic force of the magnets in the VCM16. Referring toFIGS. 2(a) and2(b), the latch18receives a bias force which pivots the latch18clockwise on the pivot shaft182. This bias force maintains the latch18in the still open state when the actuator14is brought into proximity with the magnetic-recording disk11as shown inFIG. 2(a). InFIG. 2(a), the latch18is in the most open state and the latch hook185is at the position closest to a side wall101of the base10. Specifically, the tip of the latch hook185is in contact with the protrusion on the side wall101of the base10.

As shown inFIG. 2(b), the latch18is maintained at a stand-by closed position with the coil support143being in contact with the bar182of the latch18at the stand-by position. The latch hook185extends vertically downward and the arm184supporting the latch hook185is above the actuator hook146formed on the coil support143so as to overlap each other three-dimensionally.

The method of loading the actuator14from the stand-by position is next described. After HDD1has been booted up and the magnetic-recording disk11has reached steady rotation, the actuator14starts pivoting from the stand-by position counterclockwise inFIGS. 2(a) and2(b) on the pivot shaft15at a specific speed. The latch18pivots clockwise by the magnetic bias force acting from the VCM16to the pin187with pivotal movement of the actuator14so that the latch hook185is maintained in contact with the inner side wall101of the base10(FIG. 2(a)).

The method of unloading the actuator14from being in proximity with the magnetic-recording disk is next described. The actuator14pivots clockwise on the pivot shaft15, rides on the ramp17, and stops at the stand-by position. In the pivotal movement of the actuator14, the left end of the coil support143makes contact with the bar182of the latch18to pivot the latch18counterclockwise. In the stand-by position, the latch hook185is placed on the motion path of the actuator hook146so that the latch18is in a closed state (FIG. 2(b)). In this way, in the stand-by position, the latch hook185is disposed so as to prevent the actuator14from pivoting in the direction of loading the head-slider12from above the ramp17to being in proximity with the magnetic-recording disk11.

The behavior of the latch18and the actuator14when HDD1in a non-operational state receives an external force is next described. The external force includes various directional components of force and also moment for rotating HDD1. When the actuator14receives such moment, the actuator14pivots toward the magnetic-recording disk11, which is a counterclockwise pivotal movement, or pivots away from the magnetic-recording disk11, which is a clockwise pivotal movement, depending on the direction of the moment. In this way, the actuator14can pivot in either direction by an inertial force induced by an external force; but, the actuator pivoting clockwise hits a crash stop and pivots counterclockwise as a bounce. The latch18locks these counterclockwise pivotal movements of the actuator14.

If the actuator14pivots toward the magnetic-recording disk11, the latch18, as described above, pivots in the direction to open, which is clockwise, by magnetic bias force. However, if the actuator receives an external force and starts pivoting counterclockwise, the latch hook also pivots counterclockwise even though the magnetic bias is applied clockwise. The latch hook185is on the movement path of the actuator hook146and is in a closed state. Then, the latch hook185can catch the actuator hook146, so that the head-slider12will not be loaded into proximity with the magnetic-recording disk11.

In this way, the operation of the latch18is based on the time duration for the latch18to pivot from the stand-by closed state to an open state. The open state in this situation indicates an open state when the pivoting latch18turns from a closed state into an open state. In loading, slower pivotal movement of the actuator14relative to the time duration for opening of the latch18allows the latch18to be released. When HDD1receives an external impact, the latch18locks the actuator14on the basis of a sufficiently shorter time duration of pivotal movement of the actuator14than the above-described time duration, namely a faster pivoting speed, at an impact, and counterclockwise pivotal movement of the latch18in response to the impact.

With reference now toFIGS. 4(a) and4(b), in accordance with an embodiment of the present invention, drawings are shown that show the latch in an open state and the latch in a closed state, respectively, in a method of application of a magnetic bias force from the VCM16to the latch18.FIG. 4(a) is a partial enlarged view of HDD1, showing the latch18in the still open position when the actuator14is in proximity with the magnetic-recording disk.FIG. 4(b) is a partial enlarged view of HDD1, showing the latch18being still at the stand-by close position when the actuator14is at the stand-by position. InFIGS. 4(a) and4(b), the actuator14is not shown to facilitate the discussion. As described above, in loading the actuator14, which is moving the actuator14into proximity with the magnetic-recording disk, the latch18pivots in response to a magnetic bias force induced by magnetic flux leakage from the VCM16, turning from the stand-by closed state (FIG. 4(b)) into the still open state (FIG. 4(a)).

High performance is provided for the latch18by the following two performance attributes: one is latching capability for locking the actuator14which pivots from the stand-by position toward the magnetic-recording disk11by an external force, and the other is vibration proof characteristics. The vibration of itself caused by an external impact or vibration may become a vibratory source harmful to head positioning. The magnetic bias force from the VCM16is a factor for determining these two properties.

To increase the latching capability, the time is extended when the latch18stays in the closed state, which is the state allowing the actuator14to be latched. To this end, in an embodiment of the present invention, the XY torque of the latch caused by the magnetic bias force is small. The magnetic bias force is a force for attracting the latch18into an open state. Accordingly, the XY torque is a torque when the latch18pivots on the pivot shaft181to open; and, reduction in XY torque provides a longer time for the latch to be closed.

On the other hand, to increase the vibration proof characteristics, the Z-direction component in the magnetic bias force may be increased. The latch18is inserted into the shaft181from the top cover side and the undersurface of the latch18is in contact with a mounting surface of the base. Accordingly, increase in the Z-direction magnetic bias force toward the bottom of the base leads to restriction of small movement of the latch18, preventing occurrence of vibration harmful to head positioning. When the actuator14, which is attached to the head-slider12, is in proximity with the magnetic-recording disk, the latch18is in the still open state (FIG. 4(a)). Accordingly, the Z-direction component of the magnetic bias force to the latch18is increased in the still open state.

As understood from the above description, the magnetic bias force from VCM16to act on the latch18has a large Z-direction component on the latch18in the still open state. On the other hand, even if the Z-direction magnetic bias force on the latch18in the still open state is increased, the XY torque to turn the latch18from a closed state to an open state is not increased, or the amount of increase in the XY torque is minimized.

With reference now toFIGS. 5(a) and5(b), in accordance with an embodiment of the present invention, drawings are shown that illustrate the positional relationship between the latch in an open state and a protrusion of a lower yoke, and the positional relationship between the latch in a closed state and the protrusion of the lower yoke, respectively.FIG. 5(a) is a cross-sectional view cut along the line A-A inFIG. 4(a), andFIG. 5(b) is a cross-sectional view cut along the line B-B inFIG. 4(b). The magnetic bias force to the latch18acts between magnetic flux leakage from VCM16and the magnetic pin187attached to the latch18. VCM16includes an upper yoke161, a lower yoke162, and a magnet163. The magnet163is in contact with the upper yoke161and is affixed to the upper yoke161, and is located between the upper yoke161and the lower yoke162. The number of magnets may be one or two depending on the design.

Between the upper yoke161and the lower yoke162, or between the magnet163and the lower yoke162, magnetic flux is generated. The magnetic flux leakage from the upper yoke161and the lower yoke162, or between the magnet163and the lower yoke162, acts on the magnetic pin187so that a bias force acts to attract the magnetic pin187toward the VCM16so that the latch pivots to open (clockwise inFIGS. 4(a) and4(b)). As shown inFIGS. 5(a) and5(b), the lower yoke162includes a protrusion62. There exists magnetic flux leakage from the protrusion62to generate magnetic flux leakage around the lower yoke162. The magnetic pin187receives a large bias force by the magnetic flux leakage from the protrusion62.

With reference now toFIGS. 6(a) and6(b), in accordance with an embodiment of the present invention, drawings are shown that illustrate the positional relationship between a magnetic pin of the latch in an open state and the protrusion of the lower yoke, and the positional relationship between the magnetic pin of the latch in a closed state and the protrusion of the lower yoke, respectively.FIGS. 6(a) and6(b) shows the position of the magnetic pin187at the still open position and the position of the magnetic pin187at a stand-by closed position, respectively.FIGS. 6(a) and6(b) are the drawings in which only the magnetic pin187in the latch18has been extracted fromFIGS. 5(a) and5(b), respectively. The magnetic pin187has a rugged appearance and is embedded and affixed in the body of the latch.

The protrusion62includes an arm621protruding outward, which is toward the latch18, from a plate620of the lower yoke162and a tab622bending upward from the arm621. In the configuration shown in the drawings, the arm621extends horizontally, which is vertical to the pivot shaft181, from the plate620. In one embodiment of the present invention, during manufacture, the arm621is horizontal, but may be slanted upward or downward. The tab622extends from the arm621toward the underside of the magnetic pin187. An end face623is disposed at the tip of the tab622, which is the tip of the protrusion62. The end face623is slanted relative to a horizontal plane, which is a parallel plane to the recording surface of a magnetic-recording disk, or a vertical plane to the latch pivot shaft181.

In application of an attracting force in the direction to open the latch to the magnetic pin187by the magnetic flux leakage from the protrusion62, if the actuator14is brought into proximity with the magnetic-recording disk and the latch18is in the still open state (FIG. 6(a)), the vibration proof characteristics is increased by applying a large attracting force in the Z direction, which is the direction along the latch pivot shaft181. On the other hand, for a satisfactory latching capability, in an embodiment of the present invention, the XY torque in the attracting force caused by the magnetic flux leakage is small so that the speed of pivotal movement of the latch from a closed state to an open state will not be too fast.

As shown inFIGS. 6(a) and6(b), the end face623of the protrusion62is slanted downward from the inside of VCM16toward the outside. Hence, the position in height of the end face623, which is the position in the Z direction such that the base bottom is a lower side and the top cover is an upper side, becomes higher as the magnetic pin187moves in the latch opening direction and becomes closer to VCM16. The slant of the end face623results in that the Z-direction distance between the underside871of the magnetic pin187and the end face623becomes smaller as the magnetic pin187moves in the latch opening direction and becomes closer to VCM16, and the protrusion62.

The smaller the distance in the XY plane between the magnetic pin187and the end face623, the stronger the Z-direction force to act on the magnetic pin187. Moreover, the smaller the Z-direction distance between the underside871of the magnetic pin187and the end face623, the stronger the Z-direction force to act on the magnetic pin187. Accordingly, a stronger Z-direction force can be applied to the magnetic pin187at the still open position. Thus, in an embodiment of the present invention, when the actuator14, which is attached to the head-slider12, is brought into proximity with the magnetic-recording disk, vibration of the latch18in the still open state can be effectively suppressed.

In the configuration example ofFIG. 6(a), when viewed in the Z direction, the edge closest to the magnet on the underside871of the magnetic pin187and the edge closest to the magnet on the end face623of the protrusion are substantially overlapped. The Z-direction force gradually increases while the latch18turns from a closed state to an open state and becomes strongest with the latch18in the open state.

On the other hand, the XY torque increases as the distance in the XY plane to the end face623decreases. The XY torque also increases as the Z-direction distance between the underside871of the magnetic pin187and the end face623decreases, but the increasing rate is smaller than that of the Z-direction force. Hence, the Z-direction force to the magnetic pin187at the still open position significantly increases because of the end face623, but increase in the XY torque can be suppressed and made small. In this way, the above-described slanted end surface623of the tab622can increase the Z-direction magnetic bias force on the latch18at the still open position for suppressing vibration of the latch18, and furthermore, can suppress increase in the XY torque for preventing the degradation of the latching capability, as well.

With reference now toFIGS. 7(a),7(b) and7(c), in accordance with an embodiment of the present invention, perspective views are shown that depict the structure of the protrusion62.FIG. 7(b) is an enlarged view of the portion circled inFIG. 7(a). In the protrusion62, the tab622is formed by bending relative to the arm621using a mechanical press. In one embodiment of the present invention, the slanted end face623may be formed by cutting; but, in another embodiment of the present invention, for manufacturing efficiency, the slanted end face623may be formed by using a mechanical press. In one embodiment of the present invention, the protrusion62has an arm622to adjust the position and angle of the end face623; but, in another embodiment of the present invention, such a component equivalent to the arm may not be provided. This is the same in the other protrusion structures, which are subsequently described.

The manufacture of the lower yoke162forms a protrusion protruding straight from the plate620and bends the tip, so that the protrusion having the arm621, the tab622and the end face623shown in the drawings can be formed easily. Adjustment of the length and the bend angle of the tab622yields the adjustment of the position in height, which is the position in the Z direction, of the center of the end face623and the slant angle. In this way, the arm621and the tab622allows easy positioning of the end face623at a designated position and slant. As understood from the above description, the slant angle of the end face623(a inFIG. 7(c)) is an important element for determining the Z-direction force and the XY torque to the latch18.

With reference now toFIG. 8, in accordance with an embodiment of the present invention, a bar graph is shown of simulation data indicating the Z-direction magnetic bias force and the XY torque when the slant angle α is 45° or 30° with reference to the structure having the slant angle α of 0°, which is a horizontal end face. As seen in the graph ofFIG. 8, at the slant angle α of 45° and 30°, the respective Z-direction forces are greater than and the respective XY torques are substantially the same as the references. Within the range of the slant angle α from 30° to 45°, in one embodiment of the present invention, the magnetic bias force can be applied to the latch18.

With reference now toFIGS. 9(a) and9(b), in accordance with an embodiment of the present invention, perspective views are shown that depict other shapes of the protrusion62. The protrusion62ofFIG. 9(a) is bent obliquely along the path of the magnetic pin187drawing a circle. In other words, the tab622is bent upward in the Z direction and bent within the XY plane as well. Thus, in one embodiment of the present invention, the direction, which is obtained by projecting the normal of the end face623to the XY plane, can be brought closer to a tangential direction to a path of the magnetic pin187at the point when the magnetic pin187is at a still open position. Slanting the tab along the path of the magnetic pin187provides a long distance between the pin and the protrusion at a closed position so that the XY torque can be reduced. The protrusion62may be formed by cutting so as to be bent in the XY plane and subsequently bent in the Z direction.

The protrusion62ofFIG. 9(b) includes a triangular prism, protruding from the plate620of the lower yoke162and being bent upward. Hence, the top apex624is positioned at the uppermost end. Similar to the protrusion shape shown inFIGS. 7(a) and9(a), the Z-direction distance between the magnetic pin187and the protrusion62becomes smaller as the latch18is brought closer to the still open position. Moreover, the apex624, which is a point at an end, is at the highest position such that stronger Z-direction force can be applied to the magnetic pin187at the still open position.

With reference now toFIGS. 10(a) and10(b), in accordance with an embodiment of the present invention, perspective views are shown that depict yet other shapes of the protrusion62. The aforementioned protrusions62have a slant face but the present protrusion62includes a plurality of horizontal faces different in height. To increase the Z-direction force at the still open position without degrading the latching capability, in an embodiment of the present invention, a structure for the protrusion includes a slant continuously changing the height of the structure. However, a plurality of tiered faces different in height provides the latch18with a magnetic bias force appropriate for the position of the latch.

In the configuration ofFIG. 10(a), the protrusion62includes a first horizontal face626and a second horizontal face625as the end faces of the tab622. The second face625is located closer to the plate620than the first face626and the second face625is disposed next to the first face626in the direction where the magnetic pin187moves from the closed position to the open position. The second face625is located higher than the first face626. Pressing a portion of the flat end face of the tab yields the easy formation of the first face626.

Since the magnetic pin187at the still open position is close to the second face625, the magnetic pin187receives a stronger Z-direction force. When the magnetic pin187is away from the still open position, the distance between the outer first face626and the magnetic pin187is larger than the distance between the second face625and the magnetic pin187, so that the degradation in latching capability can be prevented. In an embodiment of the present invention, to enhance the Z-direction force, the magnetic pin187at the still open position is overlapped with at least a portion of the second face625when viewed in the Z direction.

In the configuration inFIG. 10(a), the first face626and the second face625are horizontal, but these faces626and625may be slanted by slanting the tab622. Thus, the faces625and626have the same effect as the slanted end face623shown inFIG. 7. Alternatively, three or more faces different in height may be formed at the tip of the tab622.

In the configuration inFIG. 10(b), the protrusion62includes a pin627standing on the top face of the horizontally extending arm621. The pin627can be affixed easily onto the top face of the arm621by hammering. The top face271of the pin627is horizontal and is located higher than the top face211of the arm621. To the magnetic pin187at a stand-by close position, a portion of the top face211of the arm621is closer than the top face271of the pin627. The magnetic pin187at the still open position gets closer to the top surface271of the pin627, so that the magnetic pin187receives a stronger Z-direction force.

The pin627is affixed away from the end of the arm621. When the pin627is away from the still open position, the distance between the top face211of the arm621and the magnetic pin187is larger than the distance between the top face271of the pin627and the magnetic pin187, so that the degradation of latching capability can be prevented. To increase the Z-direction force, in another embodiment of the present invention, the magnetic pin187at the still open position overlaps at least a portion of the top face271of the pin627when viewed in the Z direction.

As set forth above, embodiments of the present invention have been described by way of examples; but, embodiments of the present invention are not limited to the above-described examples. The above-described examples may be easily modified, added to, and converted within the spirit and scope of embodiments of the present invention. For example, in accordance with embodiments of the present invention, a HDD using a magnetic-recording disk has been described as a disk drive, by way of example without limitation thereto, as other recording methods that utilize alternative types of disk including alternative recording media within a disk drive are also within the spirit and scope of embodiments of the present invention. For another example, in accordance with embodiments of the present invention, the latch may be applied to a HDD employing a contact start and stop (CSS) scheme in which the actuator parks at an inner area of the magnetic-recording disk.