Attenuation of a pitch mode for actuator assemblies having multiple degrees of freedom

An apparatus, in one embodiment, includes: a pivot assembly pivotably supporting a head carriage assembly, a motor coupled to the head carriage assembly for rotatably positioning the head carriage assembly about an axis of skew which extends perpendicular to a plane defined by an intended direction of media movement across the head carriage assembly and a direction of fine motion of the head carriage assembly, the fine motion direction being oriented perpendicular to the intended direction of media movement, a linear assembly supporting the pivot assembly and the head carriage assembly, the linear assembly being configured to move along the fine motion direction, and a first flexure extending between the head carriage assembly and the linear assembly, the first flexure permitting the rotatable positioning of the head carriage assembly about the axis of skew, the first flexure resisting pitching movement of the head carriage assembly relative to the linear assembly.

BACKGROUND

The present invention relates to data storage systems, and more particularly, this invention relates to improved controllability of actuator assemblies having multiple degrees of freedom.

In magnetic storage systems, magnetic transducers read data from and write data onto magnetic recording media. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. In a tape drive system, the drive moves the magnetic tape over the surface of the tape head at high speed. Moreover, read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.

An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track and linear bit density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.

BRIEF SUMMARY

An apparatus, according to one embodiment, includes: a pivot assembly pivotably supporting a head carriage assembly, a motor coupled to the head carriage assembly for rotatably positioning the head carriage assembly about an axis of skew which extends perpendicular to a plane defined by an intended direction of media movement across the head carriage assembly and a direction of fine motion of the head carriage assembly, the fine motion direction being oriented perpendicular to the intended direction of media movement, a linear assembly supporting the pivot assembly and the head carriage assembly, the linear assembly being configured to move along the fine motion direction, and a first flexure extending between the head carriage assembly and the linear assembly, the first flexure permitting the rotatable positioning of the head carriage assembly about the axis of skew, the first flexure resisting pitching movement of the head carriage assembly relative to the linear assembly.

An apparatus, according to another embodiment, includes: a pivot assembly pivotably supporting a head carriage assembly, a motor coupled to the head carriage assembly for rotatably positioning the head carriage assembly about an axis of skew which extends perpendicular to a plane defined by an intended direction of tape movement across the head carriage assembly and a direction of fine motion of the head carriage assembly, the fine motion direction being oriented perpendicular to the intended direction of tape movement, a linear assembly supporting the pivot assembly and the head carriage assembly, the linear assembly being configured to move along the fine motion direction, a first flexure extending between the head carriage assembly and the linear assembly, the first flexure permitting the rotatable positioning of the head carriage assembly about the axis of skew, the first flexure resisting pitching movement of the head carriage assembly relative to the linear assembly, a magnetic head mounted to the head carriage assembly, a drive mechanism for passing a magnetic tape over the magnetic head, and a controller electrically coupled to the motor.

Any of these embodiments may be implemented in a magnetic data storage system such as a tape drive system, which may include a magnetic head, a drive mechanism for passing a magnetic medium (e.g., recording tape) over the magnetic head, and a controller electrically coupled to the magnetic head.

DETAILED DESCRIPTION

The following description discloses several preferred embodiments of magnetic storage systems, as well as operation and/or component parts thereof.

In one general embodiment, an apparatus includes: a pivot assembly pivotably supporting a head carriage assembly, a motor coupled to the head carriage assembly for rotatably positioning the head carriage assembly about an axis of skew which extends perpendicular to a plane defined by an intended direction of media movement across the head carriage assembly and a direction of fine motion of the head carriage assembly, the fine motion direction being oriented perpendicular to the intended direction of media movement, a linear assembly supporting the pivot assembly and the head carriage assembly, the linear assembly being configured to move along the fine motion direction, and a first flexure extending between the head carriage assembly and the linear assembly, the first flexure permitting the rotatable positioning of the head carriage assembly about the axis of skew, the first flexure resisting pitching movement of the head carriage assembly relative to the linear assembly.

In another general embodiment, an apparatus includes: a pivot assembly pivotably supporting a head carriage assembly, a motor coupled to the head carriage assembly for rotatably positioning the head carriage assembly about an axis of skew which extends perpendicular to a plane defined by an intended direction of tape movement across the head carriage assembly and a direction of fine motion of the head carriage assembly, the fine motion direction being oriented perpendicular to the intended direction of tape movement, a linear assembly supporting the pivot assembly and the head carriage assembly, the linear assembly being configured to move along the fine motion direction, a first flexure extending between the head carriage assembly and the linear assembly, the first flexure permitting the rotatable positioning of the head carriage assembly about the axis of skew, the first flexure resisting pitching movement of the head carriage assembly relative to the linear assembly, a magnetic head mounted to the head carriage assembly, a drive mechanism for passing a magnetic tape over the magnetic head, and a controller electrically coupled to the motor.

FIG. 1Aillustrates a simplified tape drive100of a tape-based data storage system, which may be employed in the context of the present invention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may be implemented in the context of any type of tape drive system.

As shown, a tape supply cartridge120and a take-up reel121are provided to support a tape122. One or more of the reels may form part of a removable cartridge and are not necessarily part of the drive100. The tape drive, such as that illustrated inFIG. 1A, may further include drive motor(s) to drive the tape supply cartridge120and the take-up reel121to move the tape122over a tape head126of any type. Such head may include an array of readers, writers, or both.

Guides125guide the tape122across the tape head126. Such tape head126is in turn coupled to a controller128via a cable130. The controller128, may be or include a processor and/or any logic for controlling any subsystem of the drive100. For example, the controller128typically controls head functions such as servo following, data writing, data reading, etc. The controller128may include at least one servo channel and at least one data channel, each of which include data flow processing logic configured to process and/or store information to be written to and/or read from the tape122. The controller128may operate under logic known in the art, as well as any logic disclosed herein, and thus may be considered as a processor for any of the descriptions of tape drives included herein, in various embodiments. The controller128may be coupled to a memory136of any known type, which may store instructions executable by the controller128. Moreover, the controller128may be configured and/or programmable to perform or control some or all of the methodology presented herein. Thus, the controller128may be considered to be configured to perform various operations by way of logic programmed into one or more chips, modules, and/or blocks; software, firmware, and/or other instructions being available to one or more processors; etc., and combinations thereof.

The cable130may include read/write circuits which transmit data to the head126to be recorded on the tape122and which receive data read by the head126from the tape122. Moreover, an actuator assembly132controls a position of the head126relative to the tape122. The actuator assembly132may include a coarse actuator, fine actuator, worm screw, etc. depending on the desired embodiment. According to some exemplary embodiments, the actuator assembly132may include one or more components which enable multiple degrees of freedom for the head126relative to the tape122, as will be described in further detail below, e.g., seeFIGS. 8A-8C.

Referring still toFIG. 1A, an interface134may also be provided for communication between the tape drive100and a host (integral or external) to send and receive the data and for controlling the operation of the tape drive100and communicating the status of the tape drive100to the host, all as will be understood by those of skill in the art.

FIG. 1Billustrates an exemplary tape cartridge150according to one embodiment. Such tape cartridge150may be used with a system such as that shown inFIG. 1A. As shown, the tape cartridge150includes a housing152, a tape122in the housing152, and a nonvolatile memory156coupled to the housing152. In some approaches, the nonvolatile memory156may be embedded inside the housing152, as shown inFIG. 1B. In more approaches, the nonvolatile memory156may be attached to the inside or outside of the housing152without modification of the housing152. For example, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory156may be a Flash memory device, ROM device, etc., embedded into or coupled to the inside or outside of the tape cartridge150. The nonvolatile memory is accessible by the tape drive and the tape operating software (the driver software), and/or other device.

By way of example,FIG. 2illustrates a side view of a flat-lapped, bi-directional, two-module magnetic tape head200which may be implemented in the context of the present invention. As shown, the head includes a pair of bases202, each equipped with a module204, and fixed at a small angle α with respect to each other. The bases may be “U-beams” that are adhesively coupled together. Each module204includes a substrate204A and a closure204B with a thin film portion, commonly referred to as a “gap” in which the readers and/or writers206are formed. In use, a tape208is moved over the modules204along a media (tape) bearing surface209in the manner shown for reading and writing data on the tape208using the readers and writers. The wrap angle θ of the tape208at edges going onto and exiting the flat media support surfaces209are usually between about 0.1 degree and about 3 degrees.

The substrates204A are typically constructed of a wear resistant material, such as a ceramic. The closures204B made of the same or similar ceramic as the substrates204A.

The readers and writers may be arranged in a piggyback or merged configuration. An illustrative piggybacked configuration comprises a (magnetically inductive) writer transducer on top of (or below) a (magnetically shielded) reader transducer (e.g., a magnetoresistive reader, etc.), wherein the poles of the writer and the shields of the reader are generally separated. An illustrative merged configuration comprises one reader shield in the same physical layer as one writer pole (hence, “merged”). The readers and writers may also be arranged in an interleaved configuration. Alternatively, each array of channels may be readers or writers only. Any of these arrays may contain one or more servo track readers for reading servo data on the medium.

FIG. 2Aillustrates the tape bearing surface209of one of the modules204taken from Line2A ofFIG. 2. A representative tape208is shown in dashed lines. The module204is preferably long enough to be able to support the tape as the head steps between data bands.

In this example, the tape208includes 4 to 22 data bands, e.g., with 16 data bands and 17 servo tracks210, as shown inFIG. 2Aon a one-half inch wide tape208. The data bands are defined between servo tracks210. Each data band may include a number of data tracks, for example 1024 data tracks (not shown). During read/write operations, the readers and/or writers206are positioned to specific track positions within one of the data bands. Outer readers, sometimes called servo readers, read the servo tracks210. The servo signals are in turn used to keep the readers and/or writers206aligned with a particular set of tracks during the read/write operations.

FIG. 2Bdepicts a plurality of readers and/or writers206formed in a gap218on the module204in Circle2B ofFIG. 2A. As shown, the array of readers and writers206includes, for example, 16 writers214, 16 readers216and two servo readers212, though the number of elements may vary. Illustrative embodiments include 8, 16, 32, 40, and 64 active readers and/or writers206per array, and alternatively interleaved designs having odd numbers of reader or writers such as 17, 25, 33, etc. An illustrative embodiment includes 32 readers per array and/or 32 writers per array, where the actual number of transducer elements could be greater, e.g., 33, 34, etc. This allows the tape to travel more slowly, thereby reducing speed-induced tracking and mechanical difficulties and/or execute fewer “wraps” to fill or read the tape. While the readers and writers may be arranged in a piggyback configuration as shown inFIG. 2B, the readers216and writers214may also be arranged in an interleaved configuration. Alternatively, each array of readers and/or writers206may be readers or writers only, and the arrays may contain one or more servo readers212. As noted by considering FIGS.2and2A-B together, each module204may include a complementary set of readers and/or writers206for such things as bi-directional reading and writing, read-while-write capability, backward compatibility, etc.

FIG. 2Cshows a partial tape bearing surface view of complimentary modules of a magnetic tape head200according to one embodiment. In this embodiment, each module has a plurality of read/write (R/W) pairs in a piggyback configuration formed on a common substrate204A and an optional electrically insulative layer236. The writers, exemplified by the write transducer214and the readers, exemplified by the read transducer216, are aligned parallel to an intended direction of movement of a tape medium thereacross to form an R/W pair, exemplified by the R/W pair222. Note that the intended direction of tape movement is also referred to herein as an “intended direction of tape travel” and sometimes referred to herein as the direction of tape travel; accordingly such terms may be used interchangeably. Such direction of tape travel may be inferred from the design of the system, e.g., by examining the guides; observing the actual direction of tape travel relative to the reference point; etc. Moreover, in a system operable for bi-direction reading and/or writing, the direction of tape travel in both directions is typically parallel and thus both directions may be considered equivalent to each other.

Several R/W pairs222may be present, such as 8, 16, 32 pairs, etc. The R/W pairs222as shown are linearly aligned in a direction generally perpendicular to a direction of tape travel thereacross. However, the pairs may also be aligned diagonally, etc. Servo readers212are positioned on the outside of the array of R/W pairs, the function of which is well known.

Generally, the magnetic tape medium moves in either a forward or reverse direction as indicated by arrow220. The magnetic tape medium and head assembly200operate in a transducing relationship in the manner well-known in the art. The piggybacked MR head assembly200includes two thin-film modules224and226of generally identical construction.

Modules224and226are joined together with a space present between closures204B thereof (partially shown) to form a single physical unit to provide read-while-write capability by activating the writer of the leading module and reader of the trailing module aligned with the writer of the leading module parallel to the direction of tape travel relative thereto. When a module224,226of a piggyback head200is constructed, layers are formed in the gap218created above an electrically conductive substrate204A (partially shown), e.g., of AlTiC, in generally the following order for the R/W pairs222: an insulating layer236, a first shield232typically of an iron alloy such as NiFe (—), CZT or Al—Fe—Si (Sendust), a sensor234for sensing a data track on a magnetic medium, a second shield238typically of a nickel-iron alloy (e.g., ˜80/20 NiFe, also known as permalloy), first and second writer pole tips228,230, and a coil (not shown). The sensor may be of any known type, including those based on MR, GMR, AMR, tunneling magnetoresistance (TMR), etc.

The first and second writer poles228,230may be fabricated from high magnetic moment materials such as ˜45/55 NiFe. Note that these materials are provided by way of example only, and other materials may be used. Additional layers such as insulation between the shields and/or pole tips and an insulation layer surrounding the sensor may be present. Illustrative materials for the insulation include alumina and other oxides, insulative polymers, etc.

The configuration of the tape head126according to one embodiment includes multiple modules, preferably three or more. In a write-read-write (W-R-W) head, outer modules for writing flank one or more inner modules for reading. Referring toFIG. 3, depicting a W-R-W configuration, the outer modules252,256each include one or more arrays of writers260. The inner module254ofFIG. 3includes one or more arrays of readers258in a similar configuration. Variations of a multi-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-R head, etc. In yet other variations, one or more of the modules may have read/write pairs of transducers. Moreover, more than three modules may be present. In further approaches, two outer modules may flank two or more inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. For simplicity, a W-R-W head is used primarily herein to exemplify embodiments of the present invention. One skilled in the art apprised with the teachings herein will appreciate how permutations of the present invention would apply to configurations other than a W-R-W configuration.

FIG. 5illustrates a magnetic head126according to one embodiment of the present invention that includes first, second and third modules302,304,306each having a tape bearing surface308,310,312respectively, which may be flat, contoured, etc. Note that while the term “tape bearing surface” appears to imply that the surface facing the tape315is in physical contact with the tape bearing surface, this is not necessarily the case. Rather, only a portion of the tape may be in contact with the tape bearing surface, constantly or intermittently, with other portions of the tape riding (or “flying”) above the tape bearing surface on a layer of air, sometimes referred to as an “air bearing”. The first module302will be referred to as the “leading” module as it is the first module encountered by the tape in a three module design for tape moving in the indicated direction. The third module306will be referred to as the “trailing” module. The trailing module follows the middle module and is the last module seen by the tape in a three module design. The leading and trailing modules302,306are referred to collectively as outer modules. Also note that the outer modules302,306will alternate as leading modules, depending on the direction of travel of the tape315.

In one embodiment, the tape bearing surfaces308,310,312of the first, second and third modules302,304,306lie on about parallel planes (which is meant to include parallel and nearly parallel planes, e.g., between parallel and tangential as inFIG. 6), and the tape bearing surface310of the second module304is above the tape bearing surfaces308,312of the first and third modules302,306. As described below, this has the effect of creating the desired wrap angle α2of the tape relative to the tape bearing surface310of the second module304.

Where the tape bearing surfaces308,310,312lie along parallel or nearly parallel yet offset planes, intuitively, the tape should peel off of the tape bearing surface308of the leading module302. However, the vacuum created by the skiving edge318of the leading module302has been found by experimentation to be sufficient to keep the tape adhered to the tape bearing surface308of the leading module302. The trailing edge320of the leading module302(the end from which the tape leaves the leading module302) is the approximate reference point which defines the wrap angle α2over the tape bearing surface310of the second module304. The tape stays in close proximity to the tape bearing surface until close to the trailing edge320of the leading module302. Accordingly, read and/or write elements322may be located near the trailing edges of the outer modules302,306. These embodiments are particularly adapted for write-read-write applications.

A benefit of this and other embodiments described herein is that, because the outer modules302,306are fixed at a determined offset from the second module304, the inner wrap angle α2is fixed when the modules302,304,306are coupled together or are otherwise fixed into a head. The inner wrap angle α2is approximately tan−1(δ/W) where δ is the height difference between the planes of the tape bearing surfaces308,310and W is the width between the opposing ends of the tape bearing surfaces308,310. An illustrative inner wrap angle α2is in a range of about 0.3° to about 1.1°, though can be any angle required by the design.

Beneficially, the inner wrap angle α2on the side of the module304receiving the tape (leading edge) will be larger than the inner wrap angle α3on the trailing edge, as the tape315rides above the trailing module306. This difference is generally beneficial as a smaller α3tends to oppose what has heretofore been a steeper exiting effective wrap angle.

Note that the tape bearing surfaces308,312of the outer modules302,306are positioned to achieve a negative wrap angle at the trailing edge320of the leading module302. This is generally beneficial in helping to reduce friction due to contact with the trailing edge320, provided that proper consideration is given to the location of the crowbar region that forms in the tape where it peels off the head. This negative wrap angle also reduces flutter and scrubbing damage to the elements on the leading module302. Further, at the trailing module306, the tape315flies over the tape bearing surface312so there is virtually no wear on the elements when tape is moving in this direction. Particularly, the tape315entrains air and so will not significantly ride on the tape bearing surface312of the third module306(some contact may occur). This is permissible, because the leading module302is writing while the trailing module306is idle.

Writing and reading functions are performed by different modules at any given time. In one embodiment, the second module304includes a plurality of data and optional servo readers331and no writers. The first and third modules302,306include a plurality of writers322and no data readers, with the exception that the outer modules302,306may include optional servo readers. The servo readers may be used to position the head during reading and/or writing operations. The servo reader(s) on each module are typically located towards the end of the array of readers or writers.

By having only readers or side by side writers and servo readers in the gap between the substrate and closure, the gap length can be substantially reduced. Typical heads have piggybacked readers and writers, where the writer is formed above each reader. A typical gap is 20-35 microns. However, irregularities on the tape may tend to droop into the gap and create gap erosion. Thus, the smaller the gap is the better. The smaller gap enabled herein exhibits fewer wear related problems.

In some embodiments, the second module304has a closure, while the first and third modules302,306do not have a closure. Where there is no closure, preferably a hard coating is added to the module. One preferred coating is diamond-like carbon (DLC).

In the embodiment shown inFIG. 5, the first, second, and third modules302,304,306each have a closure332,334,336, which extends the tape bearing surface of the associated module, thereby effectively positioning the read/write elements away from the edge of the tape bearing surface. The closure332on the second module304can be a ceramic closure of a type typically found on tape heads. The closures334,336of the first and third modules302,306, however, may be shorter than the closure332of the second module304as measured parallel to a direction of tape travel over the respective module. This enables positioning the modules closer together. One way to produce shorter closures334,336is to lap the standard ceramic closures of the second module304an additional amount. Another way is to plate or deposit thin film closures above the elements during thin film processing. For example, a thin film closure of a hard material such as Sendust or nickel-iron alloy (e.g.,45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures334,336or no closures on the outer modules302,306, the write-to-read gap spacing can be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% less than commonly-used LTO tape head spacing. The open space between the modules302,304,306can still be set to approximately 0.5 to 0.6 mm, which in some embodiments is ideal for stabilizing tape motion over the second module304.

Depending on tape tension and stiffness, it may be desirable to angle the tape bearing surfaces of the outer modules relative to the tape bearing surface of the second module.FIG. 6illustrates an embodiment where the modules302,304,306are in a tangent or nearly tangent (angled) configuration. Particularly, the tape bearing surfaces of the outer modules302,306are about parallel to the tape at the desired wrap angle α2of the second module304. In other words, the planes of the tape bearing surfaces308,312of the outer modules302,306are oriented at about the desired wrap angle α2of the tape315relative to the second module304. The tape will also pop off of the trailing module306in this embodiment, thereby reducing wear on the elements in the trailing module306. These embodiments are particularly useful for write-read-write applications. Additional aspects of these embodiments are similar to those given above.

Typically, the tape wrap angles may be set about midway between the embodiments shown inFIGS. 5 and 6.

FIG. 7illustrates an embodiment where the modules302,304,306are in an overwrap configuration. Particularly, the tape bearing surfaces308,312of the outer modules302,306are angled slightly more than the tape315when set at the desired wrap angle α2relative to the second module304. In this embodiment, the tape does not pop off of the trailing module, allowing it to be used for writing or reading. Accordingly, the leading and middle modules can both perform reading and/or writing functions while the trailing module can read any just-written data. Thus, these embodiments are preferred for write-read-write, read-write-read, and write-write-read applications. In the latter embodiments, closures should be wider than the tape canopies for ensuring read capability. The wider closures may require a wider gap-to-gap separation. Therefore a preferred embodiment has a write-read-write configuration, which may use shortened closures that thus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown inFIGS. 6 and 7are similar to those given above.

A 32 channel version of a multi-module head126may use cables350having leads on the same or smaller pitch as current 16 channel piggyback LTO modules, or alternatively the connections on the module may be organ-keyboarded for a 50% reduction in cable span. Over-under, writing pair unshielded cables may be used for the writers, which may have integrated servo readers.

The outer wrap angles α1may be set in the drive, such as by guides of any type known in the art, such as adjustable rollers, slides, etc. or alternatively by outriggers, which are integral to the head. For example, rollers having an offset axis may be used to set the wrap angles. The offset axis creates an orbital arc of rotation, allowing precise alignment of the wrap angle α1.

To assemble any of the embodiments described above, conventional u-beam assembly can be used. Accordingly, the mass of the resultant head may be maintained or even reduced relative to heads of previous generations. In other approaches, the modules may be constructed as a unitary body. Those skilled in the art, armed with the present teachings, will appreciate that other known methods of manufacturing such heads may be adapted for use in constructing such heads. Moreover, unless otherwise specified, processes and materials of types known in the art may be adapted for use in various embodiments in conformance with the teachings herein, as would become apparent to one skilled in the art upon reading the present disclosure.

As previously mentioned, actuator assemblies according to various embodiments may have multiple degrees of freedom. Such actuators may be able to selectively adjust the orientation and/or position of a magnetic head with respect to a magnetic medium during operation thereof. Accordingly, actuator assemblies having control over multiple degrees of freedom may be able to compensate for various operational conditions, e.g., tape skew, tape shifting, etc.

However, conventional products having multiple degrees of freedom experience an undesirable pitching motion during operation which degrades readback quality and inhibits track following performance.

In sharp contrast, various embodiments described herein introduce a number of configurations which reduce pitching motion and thereby desirably improve performance.

FIGS. 8A-8Cdepict an apparatus800, in accordance with one embodiment. As an option, the present apparatus800may be implemented in conjunction with features from any other embodiment listed herein, such as those described with reference to the other FIGS., such asFIGS. 1A-7. However, such apparatus800and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative embodiments listed herein. Further, the apparatus800presented herein may be used in any desired environment. ThusFIGS. 8A-8C(and the other FIGS.) may be deemed to include any possible permutation.

Referring now toFIGS. 8A-8C, the apparatus800includes a pivot assembly802which is coupled to a head carriage assembly804. The pivot assembly802is preferably coupled to the head carriage assembly804such that the pivot assembly802pivotably supports the head carriage assembly804and head module812, e.g., via a pivot pin806. The pivot pin806may implement a bushing-pin configuration, as would be appreciated by one skilled in the art upon reading the present description.

Accordingly the head carriage assembly804may be able to rotate about an axis of skew, which is illustrated as extending through about the axis of the pivot pin806. Specifically, the axis of skew extends perpendicular to a plane defined by an intended direction of media movement807across the head carriage assembly804and a fine motion direction810of the head carriage assembly804. The direction of fine motion (fine motion direction810) is oriented about perpendicular to the intended direction of media movement807such that a position of the head carriage assembly804relative to the data tracks of a magnetic tape being passed thereover may be adjusted as desired, e.g., to compensate for shifting of the tape during operation.

Apparatus800additionally includes a motor808coupled to the head carriage assembly804which may be used to rotatably position the head carriage assembly804about the axis of skew. Thus, the motor808may be used to selectively rotate the head carriage assembly804about the axis of skew, thereby inducing a relative motion between the head carriage assembly804and the linear assembly814(described below). This ability to selectively rotate the head carriage assembly804about the axis of skew allows for the apparatus800to compensate for tape skew experienced during operation, e.g., while tape is being passed over the head module812.

In addition to being able to rotatably position the head carriage assembly804about the axis of skew, the motor808may also be used to move the head carriage assembly804in the fine motion direction810. Accordingly, apparatus800includes a linear assembly814which is configured to move along the fine motion direction810. Fine motion flexure824ensures that the linear assembly814travels in the fine motion direction810by restricting motion in alternate directions, e.g., along the direction of tape travel807.

The linear assembly814may additionally support the pivot pin806. Thus, the motor808may be used to selectively position the head carriage assembly804in the fine motion direction810as desired. Moreover, the linear assembly814is preferably coupled to the head carriage assembly804(e.g., via pivot pin806) such that the linear assembly814carries along the head carriage assembly804during movement in the fine motion direction810(described in further detail below). Accordingly, the motor808may enable the apparatus800to perform track following in addition to skew compensation during operation, preferably such that tape shifting may be overcome while reading from and/or writing to tape being passed over the head module812.

According to an example, which is in no way intended to limit the invention, the motor808may be an electromagnetic motor, e.g., such as a Lorentz force motor, a voice coil motor, etc. As will be appreciated by one skilled in the art upon reading the description, movement may be induced upon applying a current to each of the coils805of the electromagnetic motor. Thus, appropriate selection of the current to apply to each of the coils of the electromagnetic motor may induce a movement of the head carriage assembly804about the axis of skew, e.g., for positioning the head carriage assembly relative to the intended direction of media movement807. Moreover, appropriate selection of the current to apply to each of the coils may induce a movement of the head carriage assembly804in the fine motion direction810, e.g., for track following. It follows that the apparatus800may be selectively positioned both in the fine motion direction810and about the axis of skew.

Looking to the embodiment illustrated inFIGS. 8A-8C, the motor808includes two independently operable coils805. The coils805are positioned relative to field generators822such that the force generated by currents passing through the coils805when energized controls the position of the assembly, as would be appreciated by one skilled in the art upon reading the present description. The illustrative field generators822shown have a plurality of hard magnets823. As a result, the coils805of motor808are capable of inducing movement in a common direction and/or in opposite directions by controlling the direction and magnitude of the current through each of the coils805.

By using the coils805to induce movement in a common direction, the motor808is able to cause the head carriage assembly804to translate linearly along the fine motion direction810. Similarly, by using the coils805to induce movement in a single direction but in unequal amounts, or in opposite (e.g., antiparallel) directions, the motor808is able to cause a rotation of the head carriage assembly804about the axis of rotation, e.g., at the pivot pin806. Accordingly, current(s) may be applied to the coils805of motor808in different combinations, in terms of magnitude and/or direction, to induce different movements of the head carriage assembly804and/or linear assembly814.

It should be noted that although the motor808is depicted in the present embodiment as being used to enable selective movement of the head carriage assembly804in the fine motion direction810as well as rotatably position the head carriage assembly804about the axis of skew, different types of motor configurations may be used to enable the respective movement in different embodiments. For example, according to alternative approaches, a first motor may be used to selectively move the head carriage assembly804in the fine motion direction810while a second motor may be used to rotatably position the head carriage assembly804about the axis of skew.

Referring still toFIGS. 8A-8C, the linear assembly814is illustrated in the present embodiment as supporting the pivot assembly802and the head carriage assembly804, e.g., by being coupled thereto via pivot pin806extending therebetween. Thus, as the linear assembly814moves along the fine motion direction810, the pivot assembly802and the head carriage assembly804move as well. As previously mentioned, the linear assembly814, the pivot assembly802and the head carriage assembly804effectively move as a single piece in the fine motion direction810.

Additionally, first and second flexures816,818extend between the head carriage assembly804and the linear assembly814. Flexures816,818as seen inFIGS. 8A-8C, or in accordance with any of the other embodiments described and/or suggested herein, are included to prevent an undesirable pitching motion from occurring during reading from and/or writing to a tape which may be traveling over the head module812. Pitching motion occurs when at least a portion of the apparatus moves in a pivoting fashion about an axis of the apparatus oriented along direction807.

Pitching may occur as a result of the pivot pin806serving as the only component coupling the head carriage assembly804and the remainder of the apparatus800, e.g., the linear assembly814. Various attempts to redesign the pivot pin806itself to overcome this pitching motion proved to be unrealistic, e.g., due to spatial constraints in the apparatus800. However, by implementing the flexures816,818as disclosed herein, the pitching motion, which again is undesirable for head track following performance, is attenuated, as will be described in further detail below. As a result, the bandwidth potential of the apparatus800is increased, because of the resulting better track following performance achieved when pitching is attenuated.

With continued reference toFIGS. 8A-8C, the longitudinal axes820of the flexures816,818extend from the head carriage assembly804to the linear assembly814in a direction generally parallel to the axis of skew, e.g., within about 15 degrees from being parallel with the axis of skew. First ends of the flexures816,818are preferably coupled to the head carriage assembly804while second ends of the flexures816,818are coupled to the linear assembly814. It should be noted that the term “ends” is in no way intended to limit the invention. According to alternate approaches, portions of the first and/or second flexures816,818may extend beyond the points of contact with the head carriage assembly804and/or the linear assembly814, e.g., depending on available space. Moreover, although the flexures816,818are illustrated in the present embodiment as being coupled to the head carriage assembly804and the linear assembly814using bolts826, the flexures816,818may be coupled to the head carriage assembly804and/or the linear assembly814using any of the approaches described below, e.g., see description ofFIGS. 9A-9B.

As described above, it is preferred that the motor808is able to rotatably position the head carriage assembly804about the axis of skew. Thus, although the head carriage assembly804and the linear assembly814are coupled together by the flexures816,818, the ability to selectively rotate the head carriage assembly804about the axis of skew is preserved. Accordingly, the flexures816,818are preferably able to permit the rotatable positioning of the head carriage assembly804about the axis of skew.

Looking toFIGS. 9A-9B, detailed views of a flexure900are shown, in accordance with one embodiment. As an option, the present flexure900may be implemented in conjunction with features from any other embodiment listed herein, such as those described with reference to the other FIGS., such asFIGS. 8A-8C. Specifically,FIGS. 9A-9Billustrate detailed views of a flexure as presented in the embodiment ofFIGS. 8A-8C. Accordingly, various components ofFIGS. 9A-9Bhave common numbering with those ofFIGS. 8A-8C.

However, such flexure900and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative embodiments listed herein. Further, the flexure900presented herein may be used in any desired environment. ThusFIGS. 9A-9B(and the other FIGS.) may be deemed to include any possible permutation.

Flexure900is shown as having a rectangular cross section taken perpendicular to a longitudinal axis thereof. Moreover, a dimension of the cross section is greater (e.g., longer) in the fine motion direction810than the intended direction of media movement807. A first mounting point904may be used to couple the flexure900to a head carriage assembly as seen inFIGS. 8A-8C, while a second mounting point906may be used to couple the flexure900to a linear assembly, again as seen inFIGS. 8A-8C. However, referring still toFIGS. 9A-9B, the aforementioned orientation of the flexure900is in no way intended to limit the invention. According to other approaches, the first mounting point904may be used to couple the flexure900to a linear assembly while the second mounting point906is used to couple the flexure900to a head carriage assembly.

According to various approaches, the flexure900may be coupled to another component using different components and/or processes. Accordingly, the flexure900may be coupled to a head carriage assembly and/or linear assembly using bolts, screws, tongue and groove joints, clips, clamp, spot welding, soldering, known coupling components and/or processes, etc., depending on the desired embodiment. It follows that, depending on the fashion which the flexure900is to be coupled to a head carriage assembly and/or linear assembly, the mounting points904,906may be varied. For example, the mounting points904,906are depicted as being circular holes inFIGS. 9A-9Bwhich may correspond to using a bolt, screw, etc. to couple the flexure to the head carriage assembly and/or linear assembly. However, according to other examples, one or more of the mounting points904,906may be a tongue, groove, clamp, etc., depending on the manner in which the flexure900may be coupled to a head carriage assembly and/or linear assembly.

The shape of flexure900preserves the ability to rotatably position the head carriage assembly804about the axis of skew without being over-constrained after implementing the flexure900in an apparatus. Referring still toFIGS. 9A-9B, the flexure900is depicted as having a generally “L-shaped” profile. This allows for the first and second mounting points904,906to be offset from each other in the fine motion direction810(also referred to herein as a “vertical offset”). In other words, the centers of the first and second mounting points904,906do not align in a direction parallel to the longitudinal axis820of the flexure900. The vertical offset between mounting points904,906causes torque in the flexure when opposite forces are applied to the flexure900at the mounting points904,906. For example, when rotatably positioning the head carriage assembly of an apparatus about an axis of skew as described above, opposite forces will be applied to the flexure900at the mounting points904,906, thereby introducing torque.

Thus, depending on the dimensions and/or properties of the flexure900, torque applied to the flexure900may cause torsional deformation of the flexure900. The vertical offset allows for the skew motion to occur without causing a high tension condition when the head carriage assembly804is rotated about the axis of skew.

Moreover, the first and second mounting points904,906are also offset from each other in a direction perpendicular to the fine motion direction810(also referred to herein as a “horizontal offset”). The greater the value of the horizontal offset, the more susceptible the flexure is to torsional deformation. However, the horizontal offset is preferably low enough to prevent flexing (e.g., deformation) of the flexure900in the fine motion direction810. It follows that the horizontal offset and vertical offset may be adjusted based on the desired embodiment, e.g., depending on flexure dimensions, materials, etc. However, vertical and/or horizontal offsets of one or more flexures may be constrained by the availability of space in a corresponding tape drive. For example, the hump along the top edge of the flexure900inFIGS. 9A-9Bmay be included in a given embodiment in an attempt to gain vertical height. Accordingly, it should be noted that according to different embodiments, variations of the design (e.g., profile) of the flexure900illustrated inFIGS. 9A-9Bmay be used.

Referring again toFIGS. 8A-8C, the flexures816,818are preferably able to permit the rotatable positioning of the head carriage assembly804about the axis of skew. Thus, by selecting the dimensions and/or properties of the flexures816,818, a desired amount of deformation may be induced as a result of applying forces on the flexures816,818. Specifically, the motor808may cause the head carriage assembly804to rotate about the axis of skew while the linear assembly814is kept stationary. The relative rotation of the head carriage assembly804with respect to the linear assembly814causes opposite forces to be applied on the flexures816,818at the mounting points (e.g., seen inFIGS. 9A-9B), resulting in the flexures816,818experiencing a torsional force (e.g., torque) which causes them to torsionally deform. Accordingly, the flexures816,818are desirably able to permit the rotatable positioning of the head carriage assembly804about the axis of skew.

It follows that the flexures816,818may be resiliently deformable, e.g., such that any deformation of the flexures816,818is fully recoverable when the forces are no longer being applied. According to an exemplary embodiment, which is in no way intended to limit the invention, the flexures816,818may include steel having a thickness of about 0.1 mm. However, in other embodiments, one or more of the flexures816,818may include plastics, metals, or other materials capable of withstanding prolonged, repetitive motion while maintaining structural integrity, and/or laminates thereof.

However, it is also desirable that the flexures816,818are able to resist pitching movement of the head carriage assembly804relative to the linear assembly814, thereby preserving the track following abilities of the linear assembly814in the fine motion direction810. As described above with reference toFIGS. 9A-9B, flexures816,818ofFIGS. 8A-8Care presented herein as having a rectangular cross section taken perpendicular to a longitudinal axis thereof. Moreover, a dimension of the cross section is greater (e.g., longer) in the fine motion direction810than the intended direction of media movement807. Accordingly, the flexures816,818are effectively constrained from deforming in the fine motion direction810. In other words, the length of the flexure along its longitudinal axis820enables the flexure to effectively resist any pitching motion, as the motion is working against the cross section of the flexure900, which is resilient in nature. Moreover, it follows that the design of the flexure in the current embodiment allows for skew motion to occur with minimal resistance. The first and second flexures816,818may be coupled to the head carriage assembly804and/or the linear assembly814using any approach which preserves the ability of the flexures816,818to permit the rotatable positioning of the head carriage assembly804about the axis of skew, and resist the pitching movement of the head carriage assembly804relative to the linear assembly814. Accordingly, the first and second flexures816,818may be coupled to the head carriage assembly804and/or the linear assembly814using bolts, screws, tongue and groove joints, clips, etc., depending on the desired embodiment.

It is desirable that the first and second flexures816,818are positioned symmetrically relative to each other about the axis of skew, e.g., as shown inFIGS. 8A-8C. Positioning the flexures816,818symmetrically relative to each other about the axis of skew allows for improved rotational performance of the head carriage assembly804. Thus, it is preferred that embodiments including two or more flexures implement symmetry among the flexures, e.g., about an axis of rotation, but in no way required. For example, two or more flexures may be asymmetrically positioned relative to an axis of rotation to increase a resistance of motion in a given direction (e.g., motion in the pitch direction). Moreover, although it is preferred that flexures816,818include the same materials, dimensions, properties, etc., in some approaches, certain aspects of the flexures816,818may differ.

Although apparatus800is depicted as including two flexures inFIGS. 8A-8C, the number of flexures that may be added to a given embodiment is in no way limited thereto. According to various embodiments, apparatus800may include one, two, three, four, multiple, etc. flexures. However, depending on the number of flexures included in a given embodiment, it again desirable, but in no way required, that the flexures are positioned symmetrically relative to each other about the axis of skew, as would be appreciated by one skilled in the art upon reading the present description.

The number of flexures included in a given embodiment may affect the desired properties of the flexures, e.g., such as thickness, length, material composition, etc. For example, the desired flexure properties for embodiments having two flexures (e.g., as seen inFIGS. 8A-8C) may include flexures that are more rigid than flexure properties desired for embodiments having four or six flexures. The more flexures used in a given embodiment, the more resistant the combined flexure effect is to torsion. Specifically, adjusting the properties of the flexures utilizes a correlation between the rigidity along the longitudinal axis of a flexure, and the flexure's resistance to torsion. Thus, by adjusting the flexure properties in different embodiments, the combined effect of two flexures may be about the same as the combined effect of a different number of flexures in another embodiment.

Performance results for embodiments with and without flexures as disclosed herein are illustrated in the graphs1000,1050ofFIGS. 10A-10B. Specifically, graphs1000,1050depict transfer functions which illustrate the performance of two different apparatuses resulting from inducing motion in the fine motion direction. During the fine motion, the motion of a point of interest on the apparatuses was recorded and plotted with respect to frequency.

As an actuator assembly undergoes a dynamic high-frequency mode, e.g., during operation, the head experiences a pitching motion once a certain frequency has been reached. By implementing flexures as disclosed herein, the operating frequency which induces such pitching motion is increased, thereby improving performance. Accordingly, the transfer functions of graphs1000,1050illustrate the improvements achieved by the different embodiments disclosed herein having flexures over those without flexures.

Looking specifically, to graph1000, gain is plotted with respect to frequency. As shown, the hump (indicated by the leftmost arrow) represents the initiation of a pitching motion which occurs at just under a frequency of about 3 kHz for the case which does not include flexures. This pitching mode becomes the limiting mode in the compensator and hence restricts achievable bandwidth. However, with the implementation of flexures, the hump (indicated by the rightmost arrow) is pushed up to a higher frequency of about 3.5 kHz. Thus, graph1000illustrates the attenuation of pitching motion by implementing flexures as described above. Moreover, this increase in the operable frequency range is helpful for increasing the achievable bandwidth of the system. The improvements shown in the data of graph1000are also apparent in the phase vs. frequency plot of graph1050.

Again, by implementing flexures as described in the various embodiments herein, the onset of pitching motion is only experienced at frequencies higher than achievable using conventional products. Thus, pitching motion has a reduced impact on the anticipated bandwidth of embodiments implementing flexures as described herein.

It follows that various embodiments described herein are desirably able to resist pitching motion of magnetic heads without inhibiting the skew motion of the heads by implementing flexures which are resilient in the in-plane direction of the flexures, yet having an extent of torsional freedom, thereby allowing for skew motion to occur. It should also be noted that although many of the embodiments herein are described in terms of magnetic tape, similar and/or the same results may be achieved by implementing flexures with actuators of different media and/or applications to achieve the reduction of pitching motion thereof. Thus, the various embodiments described herein are in no way limited to implementations which include magnetic tape.