Hard disk drive

A hard disk drive includes a base, an actuator arm pivotably installed on the base, and a latch device to latch the actuator arm at a parking position. The latch device includes a latch stop that protrudes from a side wall of the base and has an inclined surface, and a latch lever pivotably installed on the base and contacts and slides along the inclined surface of the latch stop during the rotation in an unlatching direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2009-0102787, filed on Oct. 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 inventive concept relates to a hard disk drive, and more particularly, to the structure of a latch device of a hard disk drive.

2. Description of the Related Art

Hard disk drives (HDDs) are one of information storage devices. The HDD records data on a disk, or reads the data stored in the disk, by using a magnetic head. In the HDD, while flying at a predetermined height above a recording surface of a rotating disk, the magnetic head is moved by an actuator arm to a desired position to perform the above functions.

When the HDD is not in operation, that is, the rotation of a disk is stopped, the magnetic head is parked at a position out of the recording surface of the disk to prevent the magnetic head from colliding against the recording surface of the disk. The parking system of the magnetic head may include a contact start stop (CSS) method and a ramp loading method. In the CSS method, a parking zone where data is not recorded is provided at the inner circumferential side of the disk and the magnetic head is parked in the parking zone by contacting the parking zone. In the ramp loading method, a ramp is installed outside the disk and the magnetic head is parked on the ramp.

When the magnetic head is parked in the parking zone of a disk or on the ramp as described above, an external shock or vibration is applied to the HDD so that the actuator arm is freely moved and thus the magnetic head escapes from the parking zone or ramp to move over the recording surface of the disk. In this case, the magnetic head contacts the recording surface of the disk so that the magnetic head or the recording surface of the disk may be damaged. Thus, when the rotation of the disk is stopped and the magnetic head is parked in the parking zone or on the ramp, there is a need to latch the actuator arm at the parking position not to be freely rotated. To this end, a variety of latch devices are provided in the HDD.

A latch device includes a latch lever pivotably installed on a base of the HDD to confine a rear end portion of the actuator arm at the parking position. The latch lever is arranged between the base and a top yoke of a voice coil motor (VCM). A predetermined clearance (hereinafter, referred to as the upper clearance of the latch lever) for smooth rotation of the latch lever exists between the latch lever and the top yoke.

Although the upper clearance of the latch lever is necessary for the smooth rotation of the latch lever, the latch lever may be shaken in a vertical direction or vibrate when an external shock or vibration is applied to the HDD. As the latch lever is shaken in a vertical direction or vibrates, the latch lever collides against the base and/or the top yoke. An internal shock caused by the above collision may generate an error during a recording operation or reading operation of the HDD.

SUMMARY

The inventive concept provides a hard disk drive which may prevent a phenomenon in which an error is generated during the recording operation or reading operation of the HDD due to the internal shock that is generated as the latch lever is shaken in the vertical direction or vibrates, in the state in which a latch device is unlatched.

According to an aspect of the inventive concept, there is provided a hard disk drive including a base, an actuator arm pivotably installed on the base, and a latch device to latch the actuator arm at a parking position, wherein the latch device includes a latch stop protruding from a side wall of the base and having an inclined surface, and a latch lever pivotably installed on the base and contacting and sliding along the inclined surface of the latch stop during the rotation in an unlatching direction.

The inclined surface of the latch stop may be a flat surface.

The inclined surface of the latch stop may have an inclination angle within a range of 15-25 degrees.

The inclined surface of the latch stop may be a curved surface that is curved inwardly toward the base.

An accommodation groove in which the latch lever is accommodated may be formed in the inclined surface of the latch stop to stably maintain an ascending position of the latch lever in an unlatching state.

The accommodation groove of the latch stop may have a V shape.

The latch lever may include a latch arm having a contact end portion contacting the latch stop in the unlatching state, and a counterbalance disposed at the opposite side of the latch arm with respect to a rotation center of the latch lever.

The contact end portion of the latch arm may have a chamfer surface to allow the latch lever to smoothly ascend along the inclined surface of the latch stop during the rotation in the unlatching direction.

Torque to rotate the latch lever in the unlatching direction may be provided by a magnetic force acting between a steel core provided in the counterbalance and a magnet provided in a voice coil motor.

The latch lever may ascend along the inclined surface of the latch stop to a position where an upper clearance of the latch lever is removed during the rotation in the unlatching direction.

The latch lever may be arranged between a top yoke of a voice coil motor and the base, and the upper clearance is a gap between the latch lever and the top yoke

DETAILED DESCRIPTION OF THE EMBODIMENTS

The attached drawings for illustrating embodiments of the inventive concept are referred to in order to gain a sufficient understanding of the inventive concept and the merits thereof. Hereinafter, the inventive concept will be described in detail by explaining embodiments of the inventive concept with reference to the attached drawings. Like reference numerals in the drawings denote like elements.

FIG. 1is a plan view schematically illustrating the latched state of an HDD1according to an exemplary embodiment of the inventive concept.FIG. 2is a plan view schematically illustrating the unlatching state of the HDD1ofFIG. 1.FIG. 3is a partially plan view illustrating the latch device of the HDD1ofFIG. 1.FIG. 4is a partially sectioned perspective view taken along line IV-IV ofFIG. 3.FIG. 5is a partially sectioned perspective view taken along line V-V ofFIG. 3.FIGS. 6A and 6Bare schematic views for explaining the operation of the latch device in the HDD1ofFIG. 1.

Referring toFIGS. 1 and 2, the HDD1of the present exemplary embodiment includes a disk10for recording data, a spindle motor20for rotating the disk10, a head stack assembly (HSA)30to move a magnetic head (not shown) that records data on the disk10or reads the data from the disk10, to a predetermined position on the disk10, a ramp50provided in an area outside the disk10to park the magnetic head in a state in which the rotation of the disk10is stopped, a latch device100to latch the HSA30to a parking position, a base40providing a frame where constituent elements are installed, and a cover (not shown) for covering the base40.

FIGS. 1 and 2illustrate a state in which the cover covering the base40is removed. A top yoke38a(refer toFIG. 4) of a voice coil motor (VCM)39is removed for easy understanding of the structure of the HSA30.

Referring toFIGS. 1 and 2, one or more number of the disk10may be vertically stacked on a hub (not shown) of the spindle motor20. When a plurality of disks are provided as the disk10, the disks are separated by a ring shaped spacer (not shown) from each other and supported by the hub of the spindle motor20. The disk10is fixed to the hub of the spindle motor20by a clamp21arranged in the central area of the disk10.

Referring toFIGS. 1-3, the HSA30includes a slider31having the magnetic head to record data on the disk10or read the data from the disk10and to allow the magnetic head to fly above the disk10, a suspension32to elastically support the slider31against the surface of the disk10, an actuator arm34to support the suspension32and pivotably installed on the base40to allow the magnetic head to access a desired position on the disk10, a pivot shaft33pivotably supporting the actuator arm34, and the VCM39functioning as an actuator to drive the actuator arm34.

Although it is not illustrated in the accompanying drawings, the magnetic head is mounted on a lower side of the slider31and records data on the disk10by magnetizing the surface of the disk10or reads the data from the disk10by sensing the magnetic field formed on the surface of the disk10. The magnetic head substantially includes a write head to magnetize the disk10and a read head to sense the magnetic field of the disk10.

Referring toFIGS. 3-5, the VCM39includes a VCM coil36provided at the rear end portion of the actuator arm34, top and bottom yokes38aand38bfixedly installed at the base40to respectively cover the upper and lower portions of the VCM coil36, and upper and lower magnets37aand37brespectively attached to the top and bottom yokes38aand38b, thereby facing the VCM coil36. However, only one magnet may be arranged at either the upper portion or the lower portion of the VCM coil36.

The VCM39is controlled by a servo control system. The actuator arm34is rotated in a direction following the Fleming's left hand rule by reciprocal action between current input to the VCM coil36and the magnetic field formed by the magnets37aand37b.

In the above structure, when the power of the HDD1is on and thus the disk10starts to rotate, the VCM39rotates the actuator arm34counterclockwise around the pivot shaft33so as to move the magnetic head to a predetermined position on the disk10(refer toFIG. 2). The magnetic head flies above the recording surface of the disk10with a predetermined clearance therebetween by a lift force generated during the rotation of the disk10. In doing so, the magnetic head records data on the disk10or read the data from the disk10.

In contrast, when the power of the HDD1is off and thus the rotation of the disk1stops, the VCM39rotates the actuator arm34clockwise around the pivot shaft33to make the magnetic head out of the disk10. The magnetic head is parked on the ramp50as an end tap32aformed at a leading end portion of the suspension32is supported by the ramp50.

When an external shock or vibration is applied to the HDD1in which the magnetic head is at a parking position or the actuator arm34is at a parking position, the end tap32aescapes from the ramp50and the actuator arm34rotates counterclockwise so that the magnetic head may escape from the ramp50and move over the recording surface of the disk10. Since the rotation of the disk10is stopped, the magnetic head does not fly above the recording surface of the disk10, but collides against the disk10, thereby damaging the magnetic head and/or the disk10and deteriorating reliability of performance of the HDD1.

To prevent the phenomenon in which the magnetic head escapes from the ramp50due to an external shock or vibration to move over the recording surface of the disk10in the state in which the rotation of the disk10is stopped, that is, in the parking state, the HDD1according to the present exemplary embodiment includes the latch device100. In other words, the latch device100is a constituent element to latch the actuator arm34at a parking position by locking the actuator arm34to maintain the magnetic head installed at the actuator arm34to be parked on the ramp50.

Referring toFIGS. 1-5, the latch device100includes a latch lever110pivotably installed on the base40to confine the rear end portion of the actuator arm34in a latched state, a latch rotation axis150installed on the base40to penetrate the latch lever110, thereby providing the rotation center of the latch lever110, and a latch stop140protruding from a side wall41of the base40and contacting and supporting the latch lever110in the unlatching state.

The latch lever110, as illustrated inFIGS. 4 and 5, is arranged between the base40and the top yoke38aof the VCM39. A predetermined clearance C exists between the latch lever110and the top yoke38afor smooth rotation of the latch lever110, which is referred to as the upper clearance C of the latch lever110.

The latch lever110, which is pivotably installed on the base40to confine the read end portion of the actuator arm34in the latched state, includes a latch arm120extending toward one side from the rotation center of the latch lever110and a counterbalance130extending toward the other side from the rotation center of the latch lever110.

The latch arm120includes a hook (not shown) perpendicularly and downwardly bent and extending from the top end of the latch arm120and caught by a notch34aof the actuator arm34in the latched state as illustrated inFIG. 1, and a contact end portion121contacting the latch stop140in the unlatching state as illustrated inFIG. 2.

A steel core135that is a magnetic body formed of a SUS material is provided in the counterbalance130. The steel core135of the counterbalance130provides torque to rotate the latch lever110in an unlatching direction (clockwise) by reciprocal action with the magnets37aand37bprovided in the VCM39. In other words, the latch lever110receives a force to rotate in the unlatching direction (clockwise) around the latch rotation axis150by a magnetic force acting between the steel core135of the counterbalance130and the magnets37aand37bof the VCM39. For reference, the “unlatching direction” of the latch lever110signifies a direction in which the latch lever110rotates during the unlatching operation of the latch device100. In the present exemplary embodiment, the unlatching direction denotes the clockwise direction because the latch device100is installed in the lower left area of the base40.

The latch stop140protrudes from the side wall of the base40and is separated a predetermined distance from the latch arm120of the latch lever110in the latched state as illustrated inFIG. 1. As illustrated inFIG. 2, when the latch lever110rotates in the unlatching direction (clockwise) and enters in the unlatching state, the latch stop140contacts the latch arm120of the latch lever110.

The latch stop140, as illustrated inFIG. 5, includes an inclined surface141inclined upward and a vertical surface143vertically and upward extending from the inclined surface141. The inclined surface141of the latch stop140contacts a contact end portion121of the latch arm120that constitutes the latch lever110, in the unlatching state as illustrated inFIGS. 2 and 3.

The inclined surface141of the latch stop140contacts and supports the latch lever110that receives a force to rotate in the unlatching direction (clockwise) by a magnetic force between the steel core135of the latch lever110and the magnets37aand37bof the VCM39. Accordingly, during the rotation in the unlatching direction (clockwise), the latch lever110contacts the inclined surface141of the latch stop140and ascends along the inclined surface141(refer toFIGS. 6A and 6B). Thus, the upper clearance C of the latch lever110is gradually decreased and finally removed. In other words, when the latch lever110rotates in the unlatching direction (clockwise), the latch stop140contacts and supports the latch lever110and ascends along the inclined surface141. Thus, the upper clearance C of the latch lever110is decreased, preferably removed completely.

Accordingly, in the latch device100according to the present exemplary embodiment, even when an external shock or vibration is applied to the HDD1in the unlatching state, the latch lever110is no longer shaken or vibrated in the vertical direction. Thus, the phenomenon in which an error is generated during the recording or reading operation of the HDD1due to an internal shock generated as the latch lever110is shaken in the vertical direction may be prevented. A detailed description thereof will be described with a description about the operation of the latch device100that will be described later.

The inclined surface141of the latch stop140is a flat surface. The inclination angle of the inclined surface141may be chosen by considering a frictional force between the contact end portion121of the latch arm120and the inclined surface141of the latch stop140so that the latch lever110may smoothly ascend along the inclined surface141to a position where the upper clearance C of the latch lever110is completely removed. According to an experiment, the inclined surface141of the latch stop140may have an inclination angle within a range of 15-25 degrees. Alternatively, the inclined surface141of the latch stop140may be curved. For example, when the inclined surface141of the latch stop140is curved inwardly toward the base40, the ascending position of the latch lever110may be more stably maintained.

In the operation of the latch device100according to the present exemplary embodiment, first, the operation to latch the actuator arm34is described with reference toFIG. 1. When the power of the HDD1is off and thus the rotation of the disk10is stopped, the actuator arm34is rotated clockwise, thereby parking the magnetic head mounted on the leading end portion of the actuator arm34may be parked on the ramp50. The rear end portion of the actuator arm34contacts the counterbalance130of the latch lever110. The latch lever110is pushed by the actuator arm34that rotates clockwise, to be rotated in the latch direction (counterclockwise) around the latch rotation axis150, and finally stopped at the position where the counterbalance130of the latch lever110is contacted and supported by the side wall41of the base40. Accordingly, the notch34aof the actuator arm34is caught by the hook formed on the latch arm120of the latch lever110so that the actuator arm34may maintain a latch state.

A steel core35that is a magnetic body formed of a SUS material is provided at the rear end portion of the actuator arm34. The steel core35of the actuator arm34provides torque to rotate the actuator arm34clockwise by the reciprocal action with the magnets37aand37bof the VCM39so that the latch state of the actuator arm34may be further stably maintained.

Next, the operation to unlatch the actuator arm34will be described with reference toFIGS. 2 through 6Aand6B. When the power of the HDD1is on and thus the disk10starts to rotate, the actuator arm34is rotated counterclockwise, overcoming the clockwise torque by the magnetic force acting between the steel core35provided at the rear end portion of the actuator arm34and the magnets37aand37b. In doing so, the latch lever110is released from the rear end portion of the actuator arm34and is rotated in the unlatching direction (clockwise) by the magnetic force acting between the steel core135of the counterbalance130of the latch lever110and the magnets37aand37b. Thus, the notch34aof the actuator arm34rotating counterclockwise and the hook formed in the latch arm120of the latch lever110are not interfered with each other.

The latch lever110rotates in the unlatching direction (clockwise) and contacts a position “a” on the inclined surface141of the latch stop140as illustrated inFIG. 6A. After contacting the position “a” on the inclined surface141of the latch stop140, the latch lever110continuously receives a force to rotate in the unlatching direction (clockwise) by the magnetic force between the steel core135of the latch lever110and the magnets37aand37bof the VCM39. Accordingly, the latch lever110ascends along the inclined surface141to a position “b” on the inclined surface141of the latch stop140as illustrated inFIG. 6B. The position “b” denotes a position where the upper clearance C of the latch lever110(refer toFIG. 5), that is, the clearance between the latch lever110and the top yoke38a, is removed. That is, the distance D between the position “a” and the position “b” is substantially the same as the upper clearance C of the latch lever110. At the position “b”, the latch lever110contacts the top yoke38afixedly installed on the base40so that the upward movement of the latch lever110may be prevented by the top yoke38a, thereby standing still without further ascending. According toFIG. 6B, at the position “b” where the upper clearance C of the latch lever110is removed, the latch arm120of the latch lever110is separated from the vertical surface143of the latch stop140. Alternatively, the latch arm120of the latch stop140may be configured to contact the vertical surface143of the latch stop140at the position “b” where the upper clearance C of the latch lever110is removed.

Finally, since the latch lever110rotating in the unlatching direction (clockwise) stands still in contact with the inclined surface141of the latch stop140at the position “b” where the upper clearance C of the latch lever110is removed, the unlatching operation of the latch device100according to an exemplary embodiment is completed.

Even when the latch device100according to the present exemplary embodiment stands still before the position “b” where the upper clearance C of the latch lever110is removed by failing to completely overcome the frictional force between the contact end portion121of the latch arm120and the inclined surface141of the latch stop140during the unlatching operation, the latch lever110continuously receives a force to rotate in the unlatching direction (clockwise). In this state, when an external shock or vibration is applied to the HDD1, the latch lever110may reach the position “b” by ascending along the inclined surface141of the latch stop140.

As described above, since the HDD1according to the present exemplary embodiment includes the latch stop140having the inclined surface141and the latch lever110that contacts the inclined surface141of the latch stop140and ascends along the inclined surface141during the rotation in the unlatching direction, the upper clearance C of the latch lever110is removed in the unlatching state of the latch device100. Thus, when an external shock or vibration is applied to the HDD1, the latch lever110is prevented from being shaken or vibrating in the vertical direction. Accordingly, the phenomenon, in which an error is generated during the recording operation or reading operation of the HDD1due to the internal shock that is generated as the latch lever110is shaken or vibrates in the vertical direction, may be prevented.

FIGS. 7A and 7Bare schematic views for explaining the operation of a latch device200according to another exemplary embodiment of the present inventive concept. Referring toFIGS. 7A and 7B, differences between the latch device200according to the present exemplary embodiment and the latch device100that is described above will be discussed.

The structure of the latch device200according to the present exemplary embodiment is substantially the same as that of the latch device100of the above-described exemplary embodiment, except for a latch arm210constituting a latch lever220. Thus, the same constituent elements have the same reference numerals, for which descriptions will be omitted herein.

Referring toFIGS. 7A and 7B, the latch device200according to the present exemplary embodiment includes the latch stop140protruding from the side wall41of the base40and a latch lever210pivotably installed on the base40. The latch stop140includes the inclined surface141inclined upward and the vertical surface143vertically extending from the upper end of the inclined surface141. The latch lever210includes a latch arm220having a contact end portion221that contacts the inclined surface141of the latch stop140in the unlatching state. The contact end portion221of the latch arm220has a chamfer surface221a. Although the chamfer surface221ais a flat surface as illustrated inFIGS. 7A and 7B, it may alternatively be a curved surface.

In the latch device200according to the present exemplary embodiment, since the chamfer surface221ais formed on the contact end portion221of the latch arm220that directly contacts the inclined surface141of the latch stop140, as the latch lever210contacts and ascends along the inclined surface141of the latch stop140during an unlatching operation, the latch lever210may smoothly ascend along the inclined surface141of the latch stop140during an unlatching operation to the position where the upper clearance of the latch lever210is removed.

Accordingly, according to the latch device200according to the present exemplary embodiment, during the unlatching operation, the latch lever210may be prevented from being stopped before the latch lever210arrives at the position where the upper clearance of the latch lever210is removed, not overcoming the friction force between the contact end portion221of the latch arm220and the inclined surface141of the latch top140.

FIGS. 8A and 8Bare schematic views explaining the operation of a latch device300according to another exemplary embodiment of the present inventive concept. Referring toFIGS. 8A and 8B, differences between the latch device300according to the present exemplary embodiment and the latch device100that is described above will be discussed.

The structure of the latch device300according to the present exemplary embodiment is substantially the same as that of the latch device100of the above-described exemplary embodiment, except for an inclined surface341constituting a latch stop340. Thus, the same constituent elements have the same reference numerals, for which descriptions will be omitted herein.

Referring toFIGS. 8A and 8B, the latch device300according to the present exemplary embodiment includes the latch stop340protruding from the side wall41of the base40and the latch lever110pivotably installed on the base40. The latch stop340includes the inclined surface341inclined upward and a vertical surface343vertically extending from the upper end of the inclined surface341. The latch lever110includes the latch arm120having the contact end portion121that contacts the inclined surface341of the latch stop340in the unlatching state. An accommodation groove341ain which the contact end portion121of the latch arm120is accommodated is formed in the inclined surface341of the latch stop340. The accommodation groove341ais formed on the inclined surface341at a position where the latch lever110ascends, that is, a position where the upper clearance of the latch lever110is removed, or a position adjacent thereto. Although in the present exemplary embodiment the accommodation groove341ahas a V shape suitable for the contact end portion121having an angled shape, the shape of the accommodation groove341amay be appropriately selected according to the shape of the contact end portion121.

In the latch device300according to the present exemplary embodiment, in the unlatching state, since the accommodation groove341awhere the latch lever110is accommodated is formed in the inclined surface341of the latch stop340that contacts and supports the latch lever110, the contact end portion121of the latch arm120is accommodated in the accommodation groove341aof the inclined surface341at the position where the latch lever110ascends, so that the ascending position of the latch lever110may be stably maintained in the unlatching state.

As described above, according to the present inventive concept, since the latch device includes the latch stop having the inclined surface and the latch lever that contacts the inclined surface of the latch stop and ascends along the inclined surface during the rotation in the unlatching direction, the upper clearance of the latch lever is removed in the unlatching state of the latch device. Thus, when an external shock or vibration is applied to the HDD, the latch lever is prevented from being shaken or vibrating in the vertical direction. Accordingly, the phenomenon, in which an error is generated during the recording operation or reading operation of the HDD due to the internal shock that is generated as the latch lever is shaken or vibrates in the vertical direction, may be prevented.

For example, although the above-described exemplary embodiments are all about the ramp loading type HDD in which a magnetic head is parked on a ramp installed outside a disk, the present inventive concept may be applied to the CSS type HDD in which the magnetic head is parked in a parking zone provided in the inner circumferential side of the disk in contact with the parking zone.