Moveable ramp for data storage device

A data storage device includes a ramp configured to support at least one head in the data storage device, and a movement mechanism coupled to the ramp and configured to move the ramp from a first position to a second position by at least one of expansion or contraction of at least a portion of the movement mechanism. The data storage device further includes a ramp motion control module operably coupled to the movement mechanism. The ramp motion control module is configured to provide the movement mechanism with a first control signal that causes the movement mechanism to move the ramp from the first position to the second position. The data storage device additionally includes a latch configured to hold the ramp.

SUMMARY

In one embodiment, a data storage device is provided. The data storage device includes a ramp configured to support at least one head in the data storage device, and a movement mechanism coupled to the ramp and configured to move the ramp from a first position to a second position by at least one of expansion or contraction of at least a portion of the movement mechanism. The data storage device further includes a ramp motion control module operably coupled to the movement mechanism. The ramp motion control module is configured to provide the movement mechanism with a first control signal that causes the movement mechanism to move the ramp from the first position to the second position. The data storage device additionally includes a latch configured to hold the ramp.

In another embodiment, a method of operating a ramp that is configured to support a head in a data storage device is provided. The method includes moving the ramp from a first position to a second position. The method also includes selectively releasing the ramp from the second position at different speeds corresponding to different operating conditions in the data storage device.

In yet another embodiment, a data storage system in provided. The data storage system includes a ramp configured to support at least one head in the data storage system. The ramp has a plurality of positions in the data storage system. The data storage system also includes a latch configured to hold the ramp in at least two of the plurality of positions.

Other features and benefits that characterize embodiments of the disclosure will be apparent upon reading the following detailed description and review of the associated drawings.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the disclosure relate to a moveable head-support ramp for use in a data storage device (e.g., a hard disc drive (HDD)).

In general, in order to keep read/write heads from landing on one or more discs in the HDD when, for example, power is removed from the HDD, and to prevent the heads from colliding with outer edges of the discs during load and unload operations, a head-support ramp is provided adjacent to an outer diameter (OD) of the disc or discs. In a traditional HDD, the ramp is placed over portions of the disc surfaces near the OD such that the heads can easily move on and off the discs straight from/onto the ramp. Such ramps, which remain stationary during HDD operation in traditional HDDs, take space on the discs and reduce the area for recording, thereby leading to loss of storage capacity per HDD, about 5% loss in capacity in some cases.

To address this above-noted problem, embodiments of the disclosure employ a retractable ramp that moves completely off the disc(s), or nearly off the disc(s), when the OD area is to be accessed, thereby enabling data recording to be carried out on substantially entire surfaces of the disc(s). Details regarding the different embodiments are provided below in connection withFIGS.1A-6.

FIG.1Ashows an illustrative operating environment in which certain embodiments disclosed herein may be incorporated. The operating environment shown inFIG.1Ais for illustration purposes only. Embodiments of the present disclosure are not limited to any particular operating environment such as the operating environment shown inFIG.1A. Embodiments of the present disclosure are illustratively practiced within any number of different types of operating environments.

It will be understood that, when an element is referred to as being “connected,” “coupled,” or “attached” to another element, it can be directly connected, coupled or attached to the other element, or it can be indirectly connected, coupled, or attached to the other element where intervening or intermediate elements may be present. In contrast, if an element is referred to as being “directly connected,” “directly coupled” or “directly attached” to another element, there are no intervening elements present. Drawings illustrating direct connections, couplings or attachments between elements also include embodiments, in which the elements are indirectly connected, coupled or attached to each other.

FIG.1Ais a schematic illustration of a data storage device100including data storage media, heads for reading data from and/or writing data to the data storage media and a retractable ramp for supporting the heads. In data storage device100, heads102may be positioned over storage media104to read data from and/or write data to the data storage media104. In the embodiment shown inFIG.1A, the data storage media104are rotatable data storage discs, with each disc104having opposing surfaces that serve as data storage surfaces. It should be noted that, in some embodiments, a single disc may be employed instead of multiple discs. For read and write operations, a spindle motor106(illustrated schematically) rotates the media104as illustrated by arrow107and an actuator mechanism110positions the heads102relative to data tracks114on the rotating media104between an inner diameter (ID)108and an outer diameter (OD)109. Both the spindle motor106and actuator mechanism110are connected to and operated through drive circuitry112(schematically shown). Each head102is coupled to the actuator mechanism110through a suspension assembly which includes a load beam120connected to an actuator arm122of the mechanism110for example through a swage connection. The actuator mechanism110is rotationally coupled to a frame or deck (not shown) through a bearing124to rotate about axis126. Rotation of the actuator mechanism110moves the heads102in a cross-track direction as illustrated by arrow130. Each of the heads102includes one or more transducer elements (not shown) coupled to head circuitry132through flex circuit134.

As indicated above, in general, in order to keep read/write heads102from landing on discs104in a data storage device100when, for example, power is removed from the data storage device100, and to prevent the heads102from colliding with outer edges of the discs104during load and unload operations, a head-support ramp136is provided adjacent to the OD109of the discs104. As can be seen inFIG.1A, ramp136includes tapers144that have edges146that are located over portions of the disc surfaces near the OD109to enable the heads102to easily move on/off the discs from/to main portions148of tapers144where lifts or lift tabs149, which extend beyond heads102, rest when the heads102are in a “parked” position.

When, for example, heads102are in the parked position and data storage device100receives a command from a host (not shown) to access one or more disc104surfaces, actuator mechanism110rotates about axis126to move the heads102toward the disc104surfaces. Such movement of the actuator mechanism110causes the lifts or lift tabs149to move towards the discs104by following surfaces of the tapers144towards the edges146. When the heads102reach the edges146, they establish bearings (e.g., air bearings) on the disc104surfaces and are then able to access the disc104surfaces for reading and/or writing to complete executing the command received from the host.

The process of moving the heads102from the ramp136to the disc104surfaces, which is referred to as a head load (or simply a load) operation, occurs smoothly when the edges146of the tapers144are located over portions of the disc surfaces near the OD109. Similarly, the process of moving the heads102from the disc104surfaces to the ramp136, which is referred to as a head unload (or simply an unload) operation, takes place smoothly when the when the edges146of the tapers144are located over portions of the disc surfaces near the OD109. The heads102may be unloaded when, for example, the data storage device100no longer needs to access the disc104surfaces. Portions of the disc104surfaces over which the edges146of the tapers144are positioned during head load and unload operations are referred to as load/unload zones and are denoted by reference numeral150inFIG.1A.

As indicated above, not recording data in the load/unload zones may amount to a loss of about 5% storage capacity of the data storage device100. To avoid such a loss in capacity, data storage device100employs a retraction mechanism (or movement mechanism)152that is attached to ramp136and is operable to retract ramp136, such that edges146of tapers144are withdrawn from the OD109region to no longer substantially overlap the load/unload zones144after the heads102are properly loaded and supported by, for example, the air bearings, thereby making the load/unload zones150accessible for data storage/retrieval.FIG.1Bshows ramp136in a retracted position and the load/unload region being accessed by the heads102. Details regarding example retraction mechanisms are provided further below.

In some embodiments, in addition to retracting ramp136to allow for recording data in load/unload zone150during operation of data storage as shown inFIG.1B, ramp136may also be retracted when the heads102are in the parked position on ramp136. The retraction of the ramp136when the heads102are in the parked position enables up and down movement of heads102. Reasons why up and down movement of the heads102is used is some embodiments and a description of one such embodiment are provided below.

In some embodiments, a number of heads102is less than a number of disc104surfaces. For example, data storage device100ofFIGS.1A and1Bincludes 4 discs, with a total of 8 data storage surfaces, and 4 heads102. Each of the 4 heads102is coupled to the actuator mechanism110through a suspension assembly which includes load beam120connected to an actuator arm122. The actuator mechanism110, the load beams120and the actuator arms122with the heads102and lift tabs149are collectively referred to as a head stack assembly (HSA). The HSA, which is denoted by reference numeral138, may be moved along axis126between an upper position and a lower position with the help of an elevator140, which is schematically shown inFIG.1A. In the upper position shown inFIGS.1A and1B, the 4 heads interact with data storage surfaces of discs104A and104B. In the lower position (not shown), the same 4 heads interact with data storage surfaces of discs104C and104D.

In order to enable the up/down movement of the HSA138, head-support ramp136is designed to be retractable away from the OD109to permit the upward/downward movement of the ramp and HSA138without contacting the data storage media104. In order to move the HSA138from either the upper position to the lower position or from the lower position to the upper position, the HSA138is first rotated about axis126until lift tabs149of the HSA138are supported on ramp136when the edges146of the tapers144are located over portions of the disc surfaces near the OD109. Then, the ramp136, with the lift tabs149of the HSA138thereon, is retracted away from the discs104by the retraction mechanism152. Once the ramp136supporting the heads102is retraced as shown inFIG.1C, the HSA138and the ramp136may be moved up/down in unison by the elevator140. In the position shown inFIG.1C, the HSA138and the ramp136may be moved down in unison for the heads102to be able to access data storage surfaces of discs104C and104D. Details regarding one embodiment of elevator140are provided below in connection withFIG.2.

FIG.2illustrates an embodiment of an elevator200for the ramp136and the HSA138, allowing them to move in unison. Elevator200includes an upper portion201and a lower portion202. In one embodiment, each of portions201and202has a flexible first end230and a flexible second end232. In general, one or both portions201and202may be either flexible or floating. The HSA138and ramp136are positioned between the upper portion201and the lower portion202and are connected together via a base220of elevator200, thereby enabling the HSA138and the ramp136to be moved together. In one embodiment, the elevator base220may be driven up and down by a coil and a magnet (not shown) with hard stops at both ends that limit the extent of upward and downward movement of the HSA138and the ramp136. In general, any suitable driving mechanism may be used to move elevator200up and down.

In the embodiment illustrated inFIG.2, the upper limit comprises a stopper250arranged with the ramp136. The flexible first end230of the upper portion201reaches the stopper250of the ramp136and halts the upward movement. In the downward direction, the movement may be stopped by the base220reaching the flexible first end230of the lower portion202which halts the progression of the downward movement. This arrangement may be pre-assembled before being placed into a form factor for a disc drive.

In some embodiments, when a number of heads102is less than a number of disc104surfaces, and the discs104are closely spaced, at least some of the discs104may be moved up/down by retractable ramp136to enable read/write operations to be carried out. Such an embodiment is shown inFIGS.3A-3C, which are described below.

FIGS.3A-3Cillustrate an embodiment where a data storage device300may increase volumetric capacity (relative to a data storage device such as100ofFIG.1A) by allowing discs104to translate vertically, thereby permitting a decrease in relative disc spacing of at least some of the discs104to a distance that is small enough to be insufficient to accommodate an arm and head. In the embodiment ofFIGS.3A-3C, one up head (e.g., a head that interacts with upper surfaces of discs104) and one down head (e.g., a head that interacts with lower surface of discs104) may be employed to interact with discs104A-104G. In the interest of simplification, the up and down heads are not shown inFIGS.3A-3C. For example, in order to accommodate the down head to carry out a read/write operation to the lower surface of disc104E, ramp136is first moved in a horizontal or X-direction as shown by arrow302inFIG.3A. Once the edge146of ramp136reaches the position below disc104E as shown inFIG.1A, disc104E may be moved in an upward direction along a Z-axis. Up/down movement along the Z-axis is denoted by reference numeral304, and the extent of upward movement by disc104E is denoted by reference numeral306. The upward movement may be carried out by, for example, elevator140shown inFIG.1A, which may lift the ramp136, which, in turn, lifts disc104E. Once disc104E is moved to the position shown inFIG.3B, the down head may be accommodated for a read/write operation to the lower surface of disc104E. After the down head is loaded, the ramp136may be retracted to the position shown inFIG.3C(in direction308) for the down head to be able to read/write from/to load/unload zone as described above in connection withFIG.1A.

FIGS.4A-4Care diagrammatic illustrations of portions of a data storage device400that employs a retractable ramp in accordance with one embodiment.FIG.4Ais a top view of a portion of data storage device400without a ramp retraction control module ofFIG.4Binstalled, andFIG.4Cis a top view of the portion of the data storage device400with the ramp retraction control module ofFIG.4Binstalled.

Referring toFIG.4A, ramp402is shown in a retracted position where an edge404of the ramp402is only over a small portion of load/unload zone150. It should be noted that, in embodiments in which the ramp402is moved up/down in addition to being retractable, the edge404of ramp402is withdrawn past OD109to prevent the ramp402from contacting (or colliding with) the disc104during the up/down motion. As can be seen inFIG.4A, the ramp402is held in the retracted position by latch406. Latch406has a fixed end408, which may be attached to any suitable portion of the data storage device400, and a moveable end410that has a protrusion412that is configured to engage a corresponding protrusion414of the ramp402when the ramp402is retracted.

In the embodiment shown inFIG.4A, shape memory alloy (SMA) wires are employed to carry out the ramp402retraction. In general, a SMA wire may be in an expanded state at room temperature (e.g., between about 15 degrees Celsius (° C.) and about 25° C.). To cause the SMA wire to contract, an electrical current may be supplied to the SMA wire to heat the wire. The heating of the wire above room temperature causes the wire to contract. It should be noted that SMA wires are only one example of a retraction/manipulation mechanism and other suitable retraction/manipulation mechanisms may be used in other embodiments. As can be seen inFIG.4A, a first end of a first SMA wire (or wires)416is connected to ramp402, and a first end of a second SMA wire (or wires)418is connected to latch mechanism406at moveable end410. More particularly, the first end of the second SMA wire418is connected to an outer portion of the moveable end410of the latch mechanism406, with the protrusion414being on the opposite (or inner) side of moveable end410. Second ends of SMA wires416and418are connected to pins420, with one of the pins420serving as a common (or ground) connection pin. Portions of the SMA wires416and418proximate to the pins420are hidden inFIG.4A.

Referring toFIG.4B, a ramp retraction control module (or ramp motion control module)421is shown. The ramp retraction control module421includes a control chip422and pads424that are coupled to the control chip422. The coupling between the control chip422and the pads424is hidden inFIG.4B. Control chip422is configured to selectively provide power (e.g., current) to SMA wires416and418when the ramp retraction control module421is installed in data storage device400in a manner shown inFIG.4C. Here, the pads424are in contact with the pins420.

To move the ramp402to the retracted position shown inFIGS.4A and4B, control chip422supplies power (e.g., current) to SMA wire416, which responsively contracts as a result of a temperature rise caused by the current. The contraction of SMA wire416causes ramp402to retract. Withdrawal of the ramp402takes place until protrusion412on ramp402engages with corresponding protrusion414on latch406. In order to facilitate the engagement of412and414, control chip422may supply power (e.g., current) to SMA wire418substantially concurrently with current being supplied to SMA wire416. This causes SMA wire418to contract, which, in turn, causes the latch406to bend backwards near end410. The backward bending of the latch406brings protrusion414to a position where it is capable of engaging with protrusion412when latch406straightens from its bent position. Thus, with latch406in the retracted position, current supply to SMA wire418is terminated, which causes SMA wire418to expand. Expansion of the SMA wire418cause latch406to straighten, which, in turn, causes protrusion414to engage protrusion412. When protrusions412and414are engaged, supply of current to SMA wire416may be terminated by the control chip422because ramp416is now held in the retraced position by latch406.

To carry out a “quick release” of the ramp402from the retracted position to its non-retraced position (not shown inFIGS.4A-4C), control chip422provides power (e.g., current) to SMA wire418, which responsively contracts. The contraction of SMA wire418causes the latch406to bend backwards, which, in turn, results in protrusion414disengaging from protrusion412, thereby causing ramp402to return back to its non-retracted position. The quick release may be carried out when an emergency condition occurs (e.g., a loss of main power supply) in the data storage device400. The quick release may be carried out using backup or residual power in the data storage device400. A normal release of the ramp402by the latch406may be carried out during normal operation of data storage device400under normal power supply conditions. Both normal and quick release operations are described below in connection withFIGS.5A and5B.

FIGS.5A and5Bare flowcharts of methods of operating a retractable ramp and a latch mechanism in different data storage device operating modes.FIG.5Ais a flowchart of a basic retraction and latching method500when the data storage device is operating in a normal or standard mode. The normal or standard operation mode is denoted by reference numeral502. At504, a determination is made as to whether read/write operations are to be carried out in a load/unload zone of the data storage device. If no such operations are to be carried out, control returns to502. If read/operations are to be carried out in the load/unload zone, control passes to506. At506, power is provided to the retraction mechanism coupled to the ramp and to the latch (e.g., the retraction mechanism is energized). As described above in connection withFIGS.4A-4C, when power is supplied to the retraction mechanism coupled to the ramp (e.g., the SMA wire), the SMA wire contracts, thereby move the ramp to its retraced position. Supplying power to the SMA wire coupled to the latch causes the latch to bend backwards. Thus, the operations carried out at506cause the ramp to retract and the latch to bend backwards substantially simultaneously. At508, power to the latching mechanism is terminated (e.g., the SMA coupled to the latch no longer receives power or is de-energized). This results in the latch engaging the ramp, thereby causing the ramp to be held in the retracted position independently of whether power is provided to the SMA wire connected to the ramp. Thus, power to the SMA wire connected to the ramp is terminated at510.

At512, use of the load/unload zone for the read/write operations is monitored. Once it determined that load/unload zone is no longer to be used, control passes to514. At514, power is provided to the ramp retraction mechanism (e.g., power is provided to the SMA wire connected to the ramp). Thereafter, at516, power is provided to the latch mechanism (e.g., power is provided to the SMA coupled to the latch). This causes the latch to disengage from the ramp. At518, power to the ramp retraction mechanism is terminated (e.g., the power provided to the SMA wire connected to the ramp is terminated). This causes the SMA wire connected to the ramp to expand, thereby returning the ramp to its non-retracted position. After a predetermined wait period shown at520, the power to the latching mechanism is terminated (e.g., power is provided to the SMA coupled to the latch is terminated) at522, thereby returning the latch to the non-bent position.

FIG.5Bis flowchart of a method550that adds emergency data storage device shutdown-related operations to method500ofFIG.5A. In the interest of brevity, a description of502-522is not repeated in connection withFIG.5B. In method550, in addition to monitoring the use of the load/unload zone for the read/write operations at512when the ramp is in a retracted position, at552, monitoring is carried out for abnormal events taking place in the data storage device that may cause an emergency shutdown. Upon detection of an emergency shutdown (e.g., from a signal sent by a drive controller (not shown) to ramp retraction control module421) at552, control passes to554where power is provided to the latch mechanism (e.g., power is provided to the SMA wire coupled to the latch). This results in a “quick release” of the ramp, thereby causing a rapid return of the ramp to its un-retracted position for the heads to be loaded onto the ramp. Once the heads are loaded onto the ramp, the data storage device may be safely shut down.

FIG.6is a flowchart of a method600that may be carried out in a data storage device that includes a retractable ramp and an elevator for moving the ramp along a z-axis direction. In the interest of brevity, a description of502-522,552and554is not repeated. At602, a determination is made as to whether read/write operations are to be carried out at a different level (e.g., on one or more disc surfaces that may not be accessed without moving the head(s) in a z-direction to reach the surface(s) of interest). If it is determined, at602, that a level switch is to be carried out, the HSA is moved to the ramp at604. Thereafter, at606, a flag is set in a suitable memory within the data storage device to indicate that the HSA is to be moved to a different level. Thereafter, the ramp is retracted and latched in accordance with506-510described earlier in connection withFIG.5A. At512, use of the load/unload zone for the read/write operations is monitored. When it is determined, at512, that load/unload zone is no longer to be used, control passes to608. At608, a determination is made as to whether the switch level flag is set. If the switch level flag is found to be set, control passes to610where the elevator is operated to move the HSA and the ramp to the new level. The switch level flag is then reset at612.

It should be noted that the method embodiments described above may be carried out by drive circuitry112, head circuitry132, ramp136, latch mechanism406, retraction mechanism152(e.g., ramp retraction control module421), elevator140, etc. Portions of drive circuitry112, head circuitry132and ramp retraction control module421may together constitute a controller that carries out at least some control operations in the method embodiments described above.

In the above-described embodiments, the retraction mechanism employs a SMA wire the contracts when it is energized. The SMA wire is only one example of an element that may be used to carry out the retraction of the ramp. In general, any retraction mechanism that moves the ramp between non-retracted and retracted positions by expansion and/or contraction may be employed. The expansion and/or contraction may act in a manner similar to a muscle that can change length by contracting and/or stretching. Thus, the ramp retraction mechanism may also be viewed as a muscle-based system. In general, any suitable expansion/contraction system may be employed in different embodiments. For example, some alternate embodiments may employ piezoelectric elements to enable the retraction of the ramp.

In the above-described embodiments, the movement of the ramp (e.g., ramp402ofFIGS.4A-4C) is described as taking place from a non-retracted position to a retracted position, and then back to the non-retracted position. Also, the description ofFIGS.4A-4Cindicates that latch406is activated to hold the ramp402in the retracted position, and to release the ramp402to allow for movement of the ramp402back to the non-retracted position. However, in alternate embodiments, the latch406and other elements that enable latching may be configured to hold the ramp402in a number of different positions. One such embodiment is described below in connection withFIG.7.

FIG.7is a diagrammatic illustration of a portion of a data storage device700that employs a moveable ramp402in accordance with one embodiment. In the interest of brevity, elements ofFIG.7that are similar to previously-described elements included inFIGS.4A-4Care not described again in connection withFIG.7. As can be seen inFIG.7, multiple protrusions (e.g.,412A,412B and412C) are included on ramp402to selectively engage with protrusion414on latch406. In one embodiment, different levels of power (e.g., current) or times of power application or a combination of both may be provided by control chip422to SMA wire416to move the ramp402to different positions. For example, to move/bring ramp402to a first position, either no power (e.g., current) or a first level of power may be provided to SMA wire416. In the first position of the ramp402, latch406may be configured to engage with protrusion412A. To move ramp402to a second position, a second level of power (e.g., current), which may be higher than the first level of power, may be provided to SMA wire416. In the second position of the ramp402, latch406may be configured to engage with protrusion412B. To move ramp402to a third position, a third level of power (e.g., current), which may be higher than the first and second levels of power, may be provided to SMA wire416. In the third position of the ramp402, latch406may be configured to engage with protrusion412C.

As described above in connection withFIGS.4A-4C, control chip422may supply power (e.g., current) to SMA wire418to cause SMA wire418to contract, which, in turn, causes the latch406to bend backwards near end410. The backward bending of the latch406brings latch protrusion414to a position where it is capable of engaging with ramp protrusion412A,412B or412C when latch406straightens from its bent position. Thus, with latch406in the first, second or third positions, current supply to SMA wire418may be terminated, which causes SMA wire418to expand. Expansion of the SMA wire418causes latch406to straighten, which, in turn, causes latch protrusion414to engage ramp protrusion412A,412B or412C. When ramp protrusion412A,412B or412C and latch protrusion414are engaged, supply of current to the SMA wire416may be terminated by the control chip422because ramp402is now held in a suitable position by latch406engaging412A,412B or412C. The latch406may be released in any suitable manner (e.g., as described above in connection withFIGS.4A-6).

In different embodiments, latch406may be configured to hold the ramp402in a retracted position, a non-retracted position, one or more intermediate positions between the retracted and non-retracted positions, one or more rotary positions if the ramp402is rotatable, etc. In general, latch406may be configured to hold the ramp402in any suitable position. It should be noted that different types of latches may be employed in different embodiments. For example, in an alternate embodiment, the latch may be a clamp-like system where, rather than catching on a hook/protrusion, the latch holds/clamps on to the ramp402in an engaged position, and may be released from the engaged position. The latching mechanism may be SMR-based, piezo-based or may use any other suitable form of actuation including magnetic actuation. If magnetic actuation is employed for the latch, magnetic shielding may be utilized to protect the head from magnetic fields from the magnetic actuation system.