The present invention relates to data storage systems, and more particularly, this invention relates to magnetic heads for tape drives, and coatings to prevent corrosion thereon.
In magnetic storage systems, data is read from and written onto magnetic recording media utilizing magnetic transducers commonly. 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. 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 lead to increasing the track 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.
In a tape drive system, magnetic tape is moved over the surface of the tape head at high speed. This movement generally must skive off the air between the tape and the tape bearing surface (TBS) of the head in order to achieve a low spacing between the head sensor and the magnetic coating on the tape. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial to minimize signal amplitude decrease from Wallace spacing losses, which increase with increased magnetic recording flux densities. Thus the TBS is in contact with the tape so that the read element is in near contact with the tape to provide effective coupling of the magnetic field from the tape to the read element. The Wallace spacing is, among other factors, due to asperities on the tape and to erosion of the sensor due to wear. Build up of non-magnetic material between the sensor and the tape magnetic coating can also cause Wallace spacing. Corrosion or oxidation initiated at the TBS of the sensor or the protective poles surrounding the sensor can also lead to Wallace spacing losses.
Further, the AMR, GMR, TMR, etc. sensors usable in tape heads all have a propensity for corrosion. Corrosion or oxidation of the sensor at the TBS can result in surface oxidation of the sensor metals which result in an increase in the spacing between the magnetically active portion of the sensor and the magnetic coating on the tape. High level corrosion can completely destroy the magnetic response of the sensor. One proposed solution is to recess the sensor and apply a hard protective overcoat, e.g., of alumina. However, such materials are in contact with the tape, and tend to wear away, thereby leaving the sensor unprotected. The methods of depositing the hard protective coatings require large expensive tools which preclude the reapplication of a hard coating once it has been worn off. Further, such recession results in Wallace spacing signal losses, which are exacerbated the higher the density of the recorded data on the media.
For tape heads, sensors can be recessed and flux guided, but flux guides have not worked well due to head processing difficulty and to spacing loss.
Alternatively, GMR heads may be fabricated using materials that have improved corrosion resistance, but these materials may not provide optimal magnetic performance (amplitude in particular).
Head-media stiction is usually addressed by making the media rougher, but this may adversely affect the signal-to-noise ratio and thus detection capability and ultimately areal density.
A magnetic storage system according to one embodiment includes a magnetic head having a removable organic coating thereon in an amount sufficient for reducing exposure of the head to oxidation promoting materials.
A kit according to one embodiment includes a drive having a magnetic head, and a tape having an applicator portion for applying an organic coating to the magnetic head for reducing exposure of the head to oxidation promoting materials.
Other aspects, advantages and embodiments of the present invention will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrate by way of example the principles of the invention.
The following description is made for the purpose of illustrating the general principles of the present invention and is not meant to limit the inventive concepts claimed herein. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations.
Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation including meanings implied from the specification as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc.
The following description discloses several preferred embodiments of tape-based storage systems, as well as operation and/or component parts thereof.
In one general embodiment, a method for protecting a magnetic head comprises applying an organic coating to a magnetic head for reducing exposure of the head to oxidation promoting materials, and storing the magnetic head.
In another general embodiment, a method for protecting a magnetic head of a magnetic storage system comprises applying an organic coating to a magnetic head for reducing exposure of the head to oxidation promoting or corrosive materials, the organic coating being applied to the magnetic head after the head is installed in the magnetic storage system. The coating also reduces the exposure of the head to moisture (H2O) which is an essential molecule to promote corrosion.
In another general embodiment, a method comprises fabricating a tape having an applicator portion for applying an organic coating to a magnetic head for reducing exposure of the head to oxidation promoting or corrosive materials, applying the organic coating to the applicator portion of the tape, and applying a lubricant to a data portion of the tape.
In yet another general embodiment, a method comprises fabricating a tape having a data portion and a cleaning portion for removing an organic coating from a magnetic head.
As shown, a tape supply cartridge 120 and a take-up reel 121 are provided to support a tape 122. One or more of the reels may form part of a removable cassette and are not necessarily part of the system 100. The tape drive, such as that illustrated in
Guides 125 guide the tape 122 across the tape head 126. Such tape head 126 is in turn coupled to a controller assembly 128 via a cable 130. The controller 128 typically controls head functions such as servo following, writing, reading, etc. The cable 130 may include read/write circuits to transmit data to the head 126 to be recorded on the tape 122 and to receive data read by the head 126 from the tape 122. An actuator 132 controls position of the head 126 relative to the tape 122.
An interface may also be provided for communication between the tape drive and a host (integral or external) to send and receive the data and for controlling the operation of the tape drive and communicating the status of the tape drive to the host, all as will be understood by those of skill in the art.
By way of example,
The substrates 204A are typically constructed of a wear resistant material, such as a ceramic. The closures 204B made of the same or similar ceramic as the substrates 204A.
The readers and writers may be arranged in a piggyback configuration. 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 readers.
In this example, the tape 208 includes 12-22 data bands, e.g., with 16 data bands and 17 servo tracks 210, as shown in
Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. The R/W pairs 222 as 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 readers 212 are 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 arrow 220. The magnetic tape medium and head assembly 200 operate in a transducing relationship in the manner well-known in the art. The piggybacked MR head assembly 200 includes two thin-film modules 224 and 226 of generally identical construction.
Modules 224 and 226 are joined together with a space present between closures 204B 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 module 224, 226 of a piggyback head 200 is constructed, layers are formed in the gap 218 created above an electrically conductive substrate 204A (partially shown), e.g., of AlTiC, in generally the following order for the R/W pairs 222: an insulating layer 236, a first shield 232 typically of an iron alloy such as NiFe (permalloy), CZT or Al—Fe—Si (Sendust), a sensor 234 for sensing a data track on a magnetic medium, a second shield 238 typically of a nickel-iron alloy (e.g., 80/20 Permalloy), first and second writer pole tips 228, 230, and a coil (not shown).
The first and second writer poles 228, 230 may be fabricated from high magnetic moment materials such as 45/55 NiFe. Magnetoresistive (MR) sensors, such as AMR, GMR and TMR are multi-layer metals, which include, among other metals and alloys: NiFe alloys, Cu, Ru, Co, CoFe alloys, PtMn alloys, IrMn alloys, as well as others. 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.
Referring now to
In operation 302, an organic coating is applied to a magnetic head for reducing exposure of the head to oxidation promoting materials, such as water, oxygen, chlorine, bromine, sulfur, sulfides, dihydrogen sulfide, sulfur dioxide, nitrogen dioxide, and other corrosive contaminants.
The coating may be formed of virtually any protective material. Illustrative materials of which the coating may be comprised include squalane, butyl stearate, paraffins, polyvinyl chlorides, polyfluorinated films, polyvinylidene fluorides, fatty acid esters, polyurethanes, etc.
In another embodiment, the coating may comprise a tape lubricant, which may be applied separately or come from a portion of the tape such as the leading portion, trailing portion, or middle portion of the tape. In such an embodiment, the amount of tape lubricant present on the portion of the tape is preferably in excess of what is present on the other portion(s) of the tape so as to apply an amount effective to minimize or prevent corrosion.
As alluded to above, the coating may be applied to the magnetic head by a tape. In one approach, the tape may have a portion that is designed to apply the coating as it is run over the head, preferably while the tape is engaged with the head in a tape drive system, feeding the tape from a tape supply cartridge, possibly shown as tape supply cartridge 120 in
In another approach, the tape that applies the coating to the magnetic head may include an applicator portion and a data portion.
In another approach, the coating is applied to the magnetic head, and after a period of inactivity. Prior to using the magnetic head, the coating is preferably removed. Removal of the coating prior to use on tape, though may not be necessary, as the tape may rub the coating off and the additional magnetic spacing between the sensor and the magnetic coating of the tape may be low enough as to not substantially degrade the performance of the head. This can be useful, for example, if the magnetic head will be stored, shipped, or subject to conditions that might include oxidization promoting or corrosive materials, such as water, oxygen, chlorine, and other contaminants, etc. Prior to use, the coating may be removed by a cleaning portion on a tape which is adapted to remove the coating. By “removed” what is meant is that a significant portion of the coating is detached from the head, such as at least 10%, at least 25%, at least 50%, etc, Further, the coating may be completely removed. Once the coating is removed, the head may be used to read and write magnetic data to the tape. After operation of the magnetic head is suspended, another coating may be applied by running a tape across the head, the tape including an applicator portion. Alternatively, other approaches for applying the coating may be used.
In yet another approach, the tape includes a cleaning portion and a data portion.
In another approach, the magnetic tape 710 may comprise a cleaning portion 706 for removing a coating from a head, an applicator portion 704 for applying a coating to a head, and a data portion 708, as shown in
Another approach may use an applicator to apply the coating, such as a brush, stamp pad, web, nonwoven material, dropper, injector, etc. The applicator may be comprised of any suitable material. Illustrative materials include fabric, impregnated rubber, foam, etc.
In another embodiment, as shown in
In another embodiment, the applicator which is present in a drive in which the magnetic head resides presses against the magnetic head without substantial wiping. For example, the applicator stamps the magnetic head with a minimum amount of wiping, e.g., wipes less than ½ the width of the tape bearing surface measured perpendicular to the direction of media travel thereacross.
In operation 304, the magnetic head is stored. The head may be stored for many reasons such as prior to assembly in a tape drive system, after assembly and before shipment, after shipment but before use, etc. The coating may also be applied to the magnetic head during building or during packaging (e.g., for shipping, storage, or sale), or during both building and packaging of a drive in which the magnetic head resides to protect the head from corrosion promoting materials.
In operation 402, a magnetic head is installed in a magnetic storage system.
In operation 404, an organic coating is applied to a magnetic head for reducing exposure of the head to oxidation promoting materials such as water, oxygen, contaminants, etc.
In one particularly preferred embodiment, the coating may be comprised of a material selected from a group consisting of squalane, butyl stearate, a paraffin, a polyvinyl chloride, a polyfluorinated film, a polyvinylidene fluoride, a fatty acid ester, and a polyurethane.
In another embodiment, the coating may comprise a tape lubricant, which may be applied separately or come from a portion of a tape such as the leading portion, trailing portion, or middle portion of the tape.
In operation 502, a tape is fabricated having an applicator portion for applying an organic coating to a magnetic head for reducing exposure of the head to oxidation promoting materials such as water, oxygen, contaminants, etc.
In operation 504, the organic coating is applied to the applicator portion of the tape. This organic coating is then capable of being applied to a head to protect the head from oxidation promoting materials.
In operation 506, a lubricant is applied to a data portion of the tape. This lubricant can enable the data portion of the tape to run more smoothly over a head.
In one particularly preferred embodiment, the coating may be comprised of a material selected from a group consisting of squalane, butyl stearate, a paraffin, a polyvinyl chloride, a polyfluorinated film, a polyvinylidene fluoride, a fatty acid ester, and a polyurethane.
In another approach, the tape may include at least one of a data portion, an applicator portion, and a cleaning portion.
In another embodiment, the lubricant has a different composition than the coating.
In operation 602, a tape is fabricated having a data portion and a cleaning portion for removing an organic coating from a magnetic head.
In one embodiment, the tape is a data tape which has an extended leader portion that can rub the coating off the head prior to using the tape as a data tape.
In another embodiment, the ape is a special tape with a leader specially designed to remove the coating from the head when the tape is loaded onto the tape drive system. In this embodiment, the tape may then have an applicator portion which can reapply the coating to the head when the tape is unloaded from the tape drive system. A tape may have both a cleaning leader portion and an applicator portion to remove the coating from a head when loaded, and reapply the coating to a head when unloaded.
In one example, the guide mechanism 804 includes at least one guide 812 that moves away from the head 802 to create the relative spacing between the tape 806 and the head 802 as indicated by the arrows.
Preferably, the applicator 808 does not contact the tape 806 during coating application to the head 802, though contact might occur in some embodiments. Non-contact embodiments are preferred so as to avoid any applicator-induced damage to the tape 806 that could otherwise occur. The tape surface is susceptible to scratching damage, and so the tape head 802 is fabricated with smooth surfaces, and generally no abrupt discontinuities that might scratch the tape 806. It follows that an object (not part of the guide mechanism) engaging the tape 806 should also be at least as smooth as the head 802. In addition, there is less chance of debris being transferred from the applicator 808 to the tape 806 if there is no contact therewith.
In
While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
This application is a divisional of U.S. patent application Ser. No. 13/647,210 filed Oct. 8, 2012, now U.S. Pat. No. 9,159,341 which is a divisional of U.S. patent application Ser. No. 12/115,449 filed May 5, 2008, now U.S. Pat. No. 8,318,242 which are herein incorporated by reference.
Number | Name | Date | Kind |
---|---|---|---|
3827699 | Waugh | Aug 1974 | A |
4167725 | Shimizu et al. | Sep 1979 | A |
4422119 | Kawakami et al. | Dec 1983 | A |
4467382 | Huisman | Aug 1984 | A |
4522885 | Funahashi | Jun 1985 | A |
4928189 | Siddiq | May 1990 | A |
5023738 | Prenosil | Jun 1991 | A |
5023739 | Shinohara et al. | Jun 1991 | A |
5188747 | Kai et al. | Feb 1993 | A |
5327315 | Nouchi et al. | Jul 1994 | A |
5431833 | Kondo et al. | Jul 1995 | A |
5591481 | Takahashi et al. | Jan 1997 | A |
6067212 | Poorman | May 2000 | A |
6166881 | Anderson et al. | Dec 2000 | A |
6215618 | Anderson et al. | Apr 2001 | B1 |
6587307 | Raymond et al. | Jul 2003 | B1 |
6940692 | Dai et al. | Sep 2005 | B2 |
7551385 | Biskeborn et al. | Jun 2009 | B2 |
7656602 | Iben et al. | Feb 2010 | B2 |
8291388 | Golan et al. | Oct 2012 | B2 |
8318242 | Bradshaw et al. | Nov 2012 | B2 |
9159341 | Bradshaw et al. | Oct 2015 | B2 |
20040018388 | Kitamura et al. | Jan 2004 | A1 |
20060292402 | Ide | Dec 2006 | A1 |
20090273857 | Iben et al. | Nov 2009 | A1 |
20090274836 | Bradshaw et al. | Nov 2009 | A1 |
20130027811 | Bradshaw et al. | Jan 2013 | A1 |
20150380028 | Bradshaw et al. | Dec 2015 | A1 |
Number | Date | Country |
---|---|---|
360147916 | Aug 1985 | JP |
04298841 | Oct 1992 | JP |
09251607 | Sep 1997 | JP |
2000011342 | Jan 2000 | JP |
Entry |
---|
Final Office Action from U.S. Appl. No. 13/647,210, dated Mar. 23, 2015. |
Bradshaw et al., U.S. Appl. No. 14/846,713, filed Sep. 4, 2015. |
Non-Final Office Action from U.S. Appl. No. 14/846,713, dated Nov. 4, 2015. |
Non-Final Office Action from U.S. Appl. No. 13/647,210, dated Oct. 8, 2014. |
Notice of Allowance from U.S. Appl. No. 12/166,132, dated Sep. 15, 2009. |
Notice of Allowance from U.S. Appl. No. 12/115,449, dated Jul. 18, 2012. |
Non-Final Office Action from U.S. Appl. No. 12/115,449, dated Apr. 5, 2012. |
Non-Final Office Action from U.S. Appl. No. 12/115,449, dated Sep. 19, 2011. |
Bradshaw et al., U.S. Appl. No. 13/647,210, filed Oct. 8, 2012. |
Bradshaw et al., U.S. Appl. No. 12/115,449, filed May 5, 2008. |
Iben et al., U.S. Appl. No. 12/166,132, filed Jul. 1, 2008. |
Statement of Relevance of Non-Translated Foreign Documents: JP09251607 and JP04298841. |
Notice of Allowance from U.S. Appl. No. 13/647,210, dated Jun. 5, 2015. |
Statement of Relevance of Non-Translated Foreign Document: JPS60147916. |
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20150103441 A1 | Apr 2015 | US |
Number | Date | Country | |
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Parent | 13647210 | Oct 2012 | US |
Child | 14576090 | US | |
Parent | 12115449 | May 2008 | US |
Child | 13647210 | US |