WO1999013459A1 - Reader for a low-flying magnetoresistive sensor - Google Patents
Reader for a low-flying magnetoresistive sensor Download PDFInfo
- Publication number
- WO1999013459A1 WO1999013459A1 PCT/US1998/018385 US9818385W WO9913459A1 WO 1999013459 A1 WO1999013459 A1 WO 1999013459A1 US 9818385 W US9818385 W US 9818385W WO 9913459 A1 WO9913459 A1 WO 9913459A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- reader
- magnetoresistive
- magnetic
- read
- disc
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/127—Structure or manufacture of heads, e.g. inductive
- G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
- G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
- G11B5/3903—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects using magnetic thin film layers or their effects, the films being part of integrated structures
- G11B5/3906—Details related to the use of magnetic thin film layers or to their effects
- G11B5/3945—Heads comprising more than one sensitive element
- G11B5/3948—Heads comprising more than one sensitive element the sensitive elements being active read-out elements
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/127—Structure or manufacture of heads, e.g. inductive
- G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
- G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
- G11B5/3903—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects using magnetic thin film layers or their effects, the films being part of integrated structures
- G11B5/3906—Details related to the use of magnetic thin film layers or to their effects
- G11B5/3945—Heads comprising more than one sensitive element
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/488—Disposition of heads
- G11B5/4886—Disposition of heads relative to rotating disc
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/49—Fixed mounting or arrangements, e.g. one head per track
- G11B5/4907—Details for scanning
- G11B5/4915—Structure of specially adapted heads
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
- G11B33/10—Indicating arrangements; Warning arrangements
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/012—Recording on, or reproducing or erasing from, magnetic disks
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
Definitions
- the present invention relates generally to a magnetoresistive head for use in a magnetoresistive read device.
- the present invention is a magnetoresistive reader which both identifies thermal asperities and cancels out the effects of thermal asperities during a read function.
- a magnetoresistive reader portion of a magnetic read head retrieves magnetically-encoded information that is stored on a magnetic medium or disc.
- the magnetoresistive reader is typically formed of several layers that include a top shield, a bottom shield, a read element, a bias layer, and a spacer layer.
- the read element, bias layer, and spacer layer are positioned between a top and bottom shields.
- the read element is fabricated from a magnetoresistive composition, typically a ferromagnetic material such as nickel-iron (NiFe).
- NiFe nickel-iron
- the read element is fabricated on the read head such that the easy axis is transverse to the direction of disc rotation and parallel to the plane of the disc. Magnetic flux from the disc's surface causes rotation of the magnetization vector of the read element, which in turn causes a change in electrical resistivity of the read element.
- the change in resistivity of the read element can be detected by passing a sense current through the read element and measuring a voltage across the read element. External circuitry then converts the voltage information into an appropriate format and manipulates that information as necessary.
- the magnetoresistive reader Due to the low-flying nature of a read head, i.e. the read head is positioned extremely close to a rotating disc, the magnetoresistive reader is susceptible to disc projections or mechanical asperities, which interfere with the read process. Asperities on the disc can come into direct contact with a magnetoresistive read element. When a magnetoresistive read element contacts a mechanical asperity on a disc, the read element undergoes factional heating and the resistance of the magnetoresistive sensor changes accordingly. This event has been termed a "thermal asperity". A signal spike, having a duration of 1-3 microseconds, will result. During this period, the read element is unable to read.
- Another situation which may inhibit or alter the magnetoresistive reader from properly reading the information stored on a disc stems from the disc having a warped surface, rather than a perfectly planar surface.
- the magnetoresistive read element is biased causing it to be hot relative to its surroundings.
- the sensor flies very close to the disc which acts as a large heat sink.
- the proximity of the read element to the disc changes the rate of cooling of the read element and thereby changes the resistive properties of the read element. Dynamic changes in flying height, disc and head modulation, and near contact with asperities can all lead to baseline shifts in the resistance of the read element, thereby inhibiting its reading capabilities.
- the present invention is a reader of a magnetoresistive head.
- the reader includes a dual strip sensor which comprises a magnetoresistive read element for reading information from a magnetic media and a non-magnetic element.
- a spacer is positioned between the magnetoresistive read element and the non-magnetic element.
- a plurality of electrical contacts connect the magnetoresistive read element and the non-magnetic element to external circuitry.
- a non-magnetic element has a size and shape identical to the magnetoresistive read element.
- a non-magnetic sensor uses a material with a high thermal coefficient of resistivity. During a read operation, a non-magnetic element signal is then subtracted from the magnetoresistive read element signal. With this implementation, the nonmagnetic sensor resistance and magnetic properties do not need to be specifically controlled.
- the non-magnetic element is a wide detection element. By having a wide detection element, several tracks can be scanned for mechanical asperities and the locations of the mechanical asperities can be mapped out so that no information is stored in these locations. In addition, the non-magnetic element would physically protrude beyond the magnetoresistive element. Therefore, even the location of mechanical asperities which would not physically touch the read element, but would, due to their close proximity to the magnetoresistive read element, thermally affect the read process can be identified.
- Figure 1 is a layered diagram of a prior art reader.
- Figure 2 is a graph representing the signal which is read from a prior art reader of Figure 1.
- Figure 3 is a layered diagram of a reader incorporating the present invention.
- Figure 4 is a layer diagram of a portion of a reader incorporating the present invention.
- Figure 5 A is a graph representing the signal read from the magnetoresistive element of Figure 3.
- Figure 5B is a graph representing the signal read from the non- magnetic element of a reader of Figure 3.
- Figure 5C is a graph representing the output signal of the reader of Figure 3.
- Figure 6 is a layered diagram depicting a magnetoresistive element and a non-magnetic element of a first embodiment of the present invention.
- Figure 7 is a layered diagram as viewed from the air bearing surface of the first embodiment of the present invention.
- Figure 8 is a layered diagram depicting a magnetoresistive element and a non-magnetic element of a second embodiment of the present invention.
- Figure 9 is a layered diagram as viewed from the air bearing surface of a second embodiment of the present invention.
- Figure 10 is a layered diagram depicting a magnetoresistive element and a non-magnetic element of a third embodiment of the present invention.
- FIG 1 is a layered diagram of prior art reader 50 as viewed from an air bearing surface of the reader.
- Prior art reader 50 includes bottom shield 52, insulating layer or half-gap 54, magnetoresistive layer 56, spacer 58, bias layer 60, permanent magnet 62 and 64, electrical contacts 66 and 68, insulating layer or half-gap 70, and top shield 72.
- Magnetoresistive layer 56 has multiple regions including passive regions 56A and 56B separated by active region 56C.
- Active region 56C is defined as a region of magnetoresistive layer 56 between permanent magnets 62 and 64.
- Active region 56C is the region of magnetoresistive layer 56 which reads information from a track of a magnetic storage medium or disc.
- prior art reader 50 is positioned adjacent a rotating disc.
- the information on the disc causes a change in resistivity of active region 56C of magnetoresistive layer 56.
- a current is passed through magnetoresistive layer 56 via electrical contact 66 and 68 and the voltage across magnetoresistive layer 56 is measured.
- External circuitry then manipulates the information as necessary.
- Prior art reader 50 suffers from two specific situations which may inhibit or alter it from properly reading the information stored on a disc.
- the first situation is due to the low-flying nature of a read head incorporating prior art reader 50.
- the read head is positioned extremely close to a rotating disc.
- prior art reader 50 is susceptible to disc projections or mechanical asperities which interfere with the read process. Asperities on the disc can come in direct contact with active region 56C of magnetoresistive layer 56.
- active region 56C contacts a mechanical asperity on a disc active region 56C undergoes frictional heating and the resistance of magnetoresistive sensor changes accordingly. This event is called "thermal asperity".
- a signal spike having a duration of 1-3 microseconds, will result. During this period, prior art reader 50 is unable to read information from the disc.
- a second situation which may alter or inhibit it from properly reading information from the disc stems from a disc having a warped surface, rather than a perfectly planar surface.
- Magnetoresistive layer 56 is biased causing it to be hot relative to its surroundings.
- Prior art reader 50 flies very close to the disc which acts as a large heat sink.
- the proximity of active region 56C to the disc changes the rate of cooling of magnetoresistive layer 56 and thereby changes the resistive properties of magnetoresistive layer 56.
- Dynamic changes is flying height, disc and head modulation, and near contact with asperities can all lead to unwanted baseline shifts in the resistance of the read element, thereby effecting its reading capability.
- FIG 2 is a graph depicting signal 74 which is read from prior art reader 50 of Figure 1.
- Signal 74 is a typical signal, which includes wave portions 74A and spike portion 74B.
- Wave portions 74 A indicate that prior art reader 50 was positioned adjacent a disc which had a warped surface rather than a perfectly planar surface. The peaks of wave portion 74 A correspond to a time when the warped of the disc almost came into contact with prior art reader 50.
- spike portion 74B corresponds to a time when prior art reader 50 came in direct contact with a portion of the disc, perhaps due to disc projections or mechanical asperities.
- Spike portion 74B represents a thermal asperity.
- Wave portion 74A and spike portion 74B represent portions of a read signal in which the read signal is either inaccurate or unreadable, respectively. Wave portions 74 A and spike portion 74B represent denigrations in the reading capability of prior art reader 50. The present invention addresses these problems of improperly reading information from a disc.
- FIG 3 is a layered diagram of reader 150 as viewed from an air bearing surface of the reader incorporating the present invention.
- Reader 150 includes the bottom shield 152, insulating layer 154, non-magnetic layer 153, spacer 155, magnetoresistive layer 156, spacer 158, bias layer 160, permanent magnets 162 and 164, electrical contacts 166, 167, and 168, insulating layer 170, and top shield 172. Insulating layers 154 and 170 are also known as half-gaps.
- Elements or layers of reader 150 which are similar to elements or layers of prior art reader 50 are labeled similarly, with the addition of a 1 in front of the number.
- bottom shield 152 of reader 150 is identical to bottom shield 52 of prior reader 50.
- Non-magnetic layer 153 and magnetoresistive element 156 each have an active region width in the range of 0.1 microns to 4.0 microns.
- Non-magnetic layer 153 is formed from any material having a high thermal coefficient of resistivity, such as nickel or aluminum.
- Spacer layer 155 provides separation between magnetoresistive layer 156 and non-magnetic layer 153.
- Prior art dual strip magnetoresistive heads have been fabricated with each sensor formed from a magnetoresistive property. These dual strip magnetoresistive heads have shown to effectively cancel out the thermal asperity affects since the sensors are approximately the same temperature at any given time. However, fabrication and yield issues are considerable with this more complex design since the two magnetoresistive sensors must carefully be aligned, and the resistances and magnetic response must be an identical match to achieve the proper function.
- FIG. 4 is a layered diagram of a portion of reader 150 incorporating the present invention.
- Figure 4 focuses on the dual strip nature of reader 150 and includes non-magnetic layer 153, spacer 155, magnetoresistive layer 156, and electrical contacts 166, 167, and 168.
- Adjacent layers, such as spacer 158 and bias layer 160 which are fabricated adjacent magnetoresistive layer 156 have been removed for clarity. Since this a view from the air bearing surface of reader 150, a track of rotating disc would rotate past magnetoresistive layer 156 and non-magnetic layer 153 at virtually the same time and in the same number. Thus, the signals read from magnetoresistive layer 156 and nonmagnetic layer 153 would be similar in that each signal would include spike portions if the disc would come in contact with magnetoresistive layer 156 and non-magnetic layer 153 and would include wave portions when the distance between reader 150 and the disc would vary. However, the signal from magnetoresistive layer 156 would include additional information relating to the information stored on the disc. Non-magnetic layer 153 would not read this information.
- Figures 5A and 5B represent a typical signal read from magnetoresistive layer 156 and non-magnetic layer 153, respectively. As you can see, the signal shown in Figure 5 A is identical to the signal shown in Figure 2 read by prior art reader 50.
- the signal of magnetic layer 153 shown in Figure 5B mimics the signal of magnetoresistive layer 156 shown in Figure 5 A except that it does not include the signal representing information which was stored on a disc.
- Figure 5C is a signal representing a desired output signal from reader 150.
- This output signal reader is achieved by simply canceling the signal of non-magnetic layer 153 shown in Figure 5B from the signal of magnetoresistive layer 156 shown in Figure 5 A.
- representations of unwanted thermal asperities and thermal compensation have been canceled thereby producing the desired output signal representing information stored on the disc.
- Another issue which the present invention addresses is the issue of mapping out mechanical projections or asperities on a disc prior to writing data to the disc. It is desirous that, the mechanical projections or asperities of a disc are located and recorded so that no data is rewritten to these defective sites or regions.
- implementing such an approach requires a long time for each data head to scan an entire disc surface. This must be done is quarter track width to get complete and the disc is scanned radially in 40-50 micron steps.
- Magnetoresistive read elements vary in width from 1.0 microns to 4.0 microns and include 2.5 microns in mature products and 2 microns or less in current or future products. Due to the width of these elements, it will require a drive to spend a significant amount of time, such as 8-12 hours, searching for the defects. In addition, existing magnetoresistive read elements are most reliable when a low amount of current is supplied to the element. However, the more current that is passed into the element, the greater the probability of detecting asperities. Thus, there is a trade-off of prior art magnetoresistive heads between reliable reading and proper detection of asperities.
- FIG 6 is a layered diagram of magnetoresistive sensor 200 depicting magnetoresistive element 202 and non-magnetic element 204 of a first alternate embodiment of the present invention.
- magnetoresistive sensor 200 includes magnetoresistive element 202, nonmagnetic element 204, write gap 206, Sendust layer 208, and shields 210, 212, 214, and 216.
- Figure 6 also shows disc 218 which would be rotating under magnetoresistive sensor 200.
- Figure 7 is a layered diagram as viewed from the air-bearing surface of magnetoresistive sensor 200 shown in Figure 6.
- non-magnetic element 204 is a wide resistive element formed from any non-magnetic material which is susceptible to heat transfer, such as nickel or aluminum.
- magnetoresistive sensor 200 shown in Figures 6 and 7 utilizes a wide resistive element, as compared to magnetoresistive element 202, for non-magnetic element 204 as an asperity sensor.
- a wide element used for non-magnetic element 204 significantly cuts down on the amount of time used to scan locations of all tracks of a disc and to detect and map out all thermal asperities.
- the use of a non-magnetic material can be used whether or not the magnetic media is DC erased. No information will be stored at these locations.
- a higher biased current can be provided through a non-magnetic element 204 which would improve the sensitivity to asperities during a mapping process.
- non-magnetic element 204 as compared to a magnetic element, would be in the range of 10- 100 microns which would allow a disc surface to be scanned very quickly.
- the width of magnetoresistive element 202 is in the range of 0.1 to 4.0 microns.
- Figures 8 and 9 represent layered diagrams depicting a second alternate embodiment of the present invention.
- Figures 8 and 9 depict magnetoresistive element 202 and non-magnetic element 204 positioned between shields 210 and 212. The advantage of this approach is that additional shields are not necessary.
- Figure 10 depicts a layered diagram showing a third alternate embodiment of the present invention. While this third alternate embodiment of magnetoresistive sensor is very similar to that shown in Figures 6 and 7, magnetoresistive element 202 is positioned on recession 220. Therefore, nonmagnetic element 204 is in closer proximity to disc 218 than magnetoresistive element 202. Thus, non-magnetic element 204 would have the capability of detecting mechanical asperities which would not come in contact with magnetoresistive element 202, however would effect the reading capabilities due to heat transfer. With all of the embodiments shown in Figures 6-10, the magnetoresistive element and the non-magnetic layer or element are connected to external circuitry via electrical contacts, such as contacts 166, 167, and 168.
- electrical contacts such as contacts 166, 167, and 168.
- the present invention is magnetoresistive read head which provides the dual purposes of effectively canceling out any thermal asperity affects during a read operation and which can scan an entire disc surface relatively quickly in order to map out any mechanical asperities on the disc and record the locations of the defective sites so that no data is written to these regions.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020007002399A KR20010023744A (en) | 1997-09-08 | 1998-09-04 | Reader for a low-flying magnetoresistive sensor |
DE19882654T DE19882654T1 (en) | 1997-09-08 | 1998-09-04 | Reading device for a low-flying magnetoresistive sensor |
JP2000511155A JP4125479B2 (en) | 1997-09-08 | 1998-09-04 | Low flying magnetoresistive sensor reader |
GB0001556A GB2343055A (en) | 1997-09-08 | 1998-09-04 | Reader for a low-flying magnetoresistive sensor |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US5823797P | 1997-09-08 | 1997-09-08 | |
US60/058,237 | 1997-09-08 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1999013459A1 true WO1999013459A1 (en) | 1999-03-18 |
Family
ID=22015541
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/018384 WO1999013457A2 (en) | 1997-09-08 | 1998-09-04 | Reader for a low-flying magnetoresistive sensor |
PCT/US1998/018385 WO1999013459A1 (en) | 1997-09-08 | 1998-09-04 | Reader for a low-flying magnetoresistive sensor |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/018384 WO1999013457A2 (en) | 1997-09-08 | 1998-09-04 | Reader for a low-flying magnetoresistive sensor |
Country Status (6)
Country | Link |
---|---|
JP (1) | JP4125479B2 (en) |
KR (1) | KR20010023744A (en) |
CN (1) | CN1197054C (en) |
DE (1) | DE19882654T1 (en) |
GB (1) | GB2343055A (en) |
WO (2) | WO1999013457A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6502997B1 (en) | 1999-03-10 | 2003-01-07 | Samsung Electronics Co., Ltd. | Connector and cable having transducer and receiver for optical transmission |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH079760U (en) * | 1993-07-19 | 1995-02-10 | 有限会社大和技研 | Unity band |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5270892A (en) * | 1992-06-05 | 1993-12-14 | Hewlett-Packard Company | Conductor configuration for magnetoresistive transducers |
JPH08287444A (en) * | 1995-04-18 | 1996-11-01 | Hitachi Ltd | Magnetic disk device |
US5793207A (en) * | 1996-10-09 | 1998-08-11 | International Business Machines Corporation | Disk drive with a thermal asperity reduction circuitry using a spin valve sensor |
-
1998
- 1998-09-04 JP JP2000511155A patent/JP4125479B2/en not_active Expired - Fee Related
- 1998-09-04 DE DE19882654T patent/DE19882654T1/en not_active Withdrawn
- 1998-09-04 KR KR1020007002399A patent/KR20010023744A/en not_active Application Discontinuation
- 1998-09-04 WO PCT/US1998/018384 patent/WO1999013457A2/en not_active Application Discontinuation
- 1998-09-04 CN CNB988088916A patent/CN1197054C/en not_active Expired - Fee Related
- 1998-09-04 WO PCT/US1998/018385 patent/WO1999013459A1/en not_active Application Discontinuation
- 1998-09-04 GB GB0001556A patent/GB2343055A/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5270892A (en) * | 1992-06-05 | 1993-12-14 | Hewlett-Packard Company | Conductor configuration for magnetoresistive transducers |
JPH08287444A (en) * | 1995-04-18 | 1996-11-01 | Hitachi Ltd | Magnetic disk device |
US5793207A (en) * | 1996-10-09 | 1998-08-11 | International Business Machines Corporation | Disk drive with a thermal asperity reduction circuitry using a spin valve sensor |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6502997B1 (en) | 1999-03-10 | 2003-01-07 | Samsung Electronics Co., Ltd. | Connector and cable having transducer and receiver for optical transmission |
Also Published As
Publication number | Publication date |
---|---|
WO1999013457A2 (en) | 1999-03-18 |
JP2001516119A (en) | 2001-09-25 |
GB2343055A (en) | 2000-04-26 |
KR20010023744A (en) | 2001-03-26 |
DE19882654T1 (en) | 2000-08-24 |
GB0001556D0 (en) | 2000-03-15 |
JP4125479B2 (en) | 2008-07-30 |
CN1269903A (en) | 2000-10-11 |
CN1197054C (en) | 2005-04-13 |
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