CN1109621A - Magnetoresistive head and magnetic disc apparatus - Google Patents

Magnetoresistive head and magnetic disc apparatus Download PDF

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Publication number
CN1109621A
CN1109621A CN 94115634 CN94115634A CN1109621A CN 1109621 A CN1109621 A CN 1109621A CN 94115634 CN94115634 CN 94115634 CN 94115634 A CN94115634 A CN 94115634A CN 1109621 A CN1109621 A CN 1109621A
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CN
China
Prior art keywords
temperature
magnetoresistance element
temperature change
magnetoresistive head
layer
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Pending
Application number
CN 94115634
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Chinese (zh)
Inventor
濑尾洋右
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Hitachi Ltd
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Hitachi Ltd
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Publication of CN1109621A publication Critical patent/CN1109621A/en
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    • 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
    • G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
    • 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
    • G11B5/455—Arrangements for functional testing of heads; Measuring arrangements for heads

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Magnetic Heads (AREA)
  • Recording Or Reproducing By Magnetic Means (AREA)

Abstract

A magnetoresistive head is provided, in which a bias layer 5 in the vicinity of a magnetoresistive element is also used as a temperature detector for detecting the temperature change of the magnetoresistive element, and a signal thus detected is outputted through electrodes. The level of the signal is corrected appropriately and subtracted from the output signal of the magnetoresistive element. In this way, the thermal asperity is removed from the output signal of the magnetoresistive element.

Description

Magnetoresistive head and magnetic disc apparatus
The present invention relates to a kind of magnetoresistive head (MR head), perhaps more particularly relate to a kind of MR head that can remove the MR head output fluctuation (thermal fluctuation thermal asperity) that causes owing to temperature variation such as the frictional heat that when this MR head contacts with magnetic recording media, occurs.
Adopt a MR head that the MR element reproduces, be proposed device as the recording density that increases disk.The resistance of this MR element changes along with magnetic field, and the traditional induction head height of its reproduction (playback) remolding sensitivity.Under reproduction mode, a constant electric current is added on this MR element, the resistance variations when changing to detect voltage.Can not write on this MR head, thereby write with one that inductive head combines actually and as a MR-induction composite head (hereinafter referred to as magnetic head or MR/IND head).
As shown in Figure 5, this magnetic head can directly contact with medium, or by since jut on the dish or the dust that causes of dust and with the medium indirect contact.At contact point, frictional heat has caused rapid temperature to rise.Under near contact point is positioned at the MR element the situation, the resistance of known MR element will be with temperature change, thereby causes the output fluctuation.This output fluctuation is called as thermal fluctuation (thermal asperity).An example that has shown this thermal fluctuation among Fig. 7.In this way, thermal fluctuation 72 is rendered as the form that is added on the data-signal 71.
In JP-A-2-154310 and JP-A-2-54403, announce the conventional art of removing thermal fluctuation.The former is by disposing two MR elements in a different manner, thereby removes thermal fluctuation by Differential Detection.
In a kind of method in back, detect positive envelope 73 and negative envelope 74 Fig. 7 from the detection signal that is superimposed with thermal fluctuation; Thermal fluctuation detects from these envelopes.So the thermal fluctuation that obtains is used to thermal fluctuation is separated from the signal that comprises thermal fluctuation.
The problem of last method is to require and two track widths that the MR element is corresponding, thereby structurally is difficult to reduce track width.
Though it is unrestricted that back one method reduces track width, its signal Processing needs the long time, thereby is difficult to read within the predetermined time the address signal of magnetic track and determines whether the address of so reading is the address that will visit.Therefore, a kind of possible solution is to be used in the circuit of removing thermal fluctuation to avoid connecting under general state, but makes this circuit connection again when detecting the data error that may cause thermal fluctuation turn over a circle when medium after, thereby except that denoising.Yet this method can not be handled in real time, thereby reduces the flow of data.In addition, thermal fluctuation experience sharply change or the situation of the frequency approach signal frequency of thermal fluctuation under, just can not obtain correct envelope.As a result, input signal can not be proofreaied and correct completely, thereby often causes data error.
Purpose of the present invention provides a kind of MR head and a kind of disk unit, has wherein removed thermal fluctuation under the situation that does not limit width in real time.
According to the present invention, a kind of magnetoresistive head is provided, and it comprises that a magnetoresistance element that is used to utilize magnetoresistance effect to detect magnetic field, one are arranged near this magnetoresistance element and are used to detect the Temperature Detector of the information relevant with the temperature change of this magnetoresistance element and are used to export this detected temperatures and changes the device of information as output.
Consider that this Temperature Detector is set near this fact of magnetoresistance element, the temperature of Temperature Detector is substantially equal to the temperature of magnetoresistance element.The resistance of this Temperature Detector is according to temperature variation, and this resistance changes and because the ratio that changes over that the temperature change of magnetoresistance element causes.As a result, by the output of suitable amplification Temperature Detector and the output of magnetoresistance element, just can obtain poor between these two outputs.In this way, realized a kind of temperature compensation, from the output of magnetoresistance element, to eliminate the influence of temperature change.
Fig. 1 is a circuit diagram, is used to explain the temperature compensation according to MR head of the present invention;
Fig. 2 has shown the structure of MR head according to an embodiment of the invention;
Fig. 3 has shown the structure of MR head according to another embodiment of the invention;
Fig. 4 has shown the structure of MR head according to still another embodiment of the invention;
Fig. 5 is used to explain magnetic head and coils the mode that contacts;
Fig. 6 has shown a kind of structure of disc apparatus;
Fig. 7 is used to illustrate the reproducing signal that has obtained when having produced thermal fluctuation.
Below in conjunction with Fig. 1 and 2 one embodiment of the present of invention are described.
Fig. 2 has shown an example according to the structure of a kind of magnetic head of the present invention.For the sake of simplicity, only shown the magnetoresistance element part relevant with the present invention.This figure is the displayed record head not, also show be used to make MR element 7 avoid detecting the position beyond the position that will read from MR element 7 magnetic field go up shielding device or the like.
This magnetic head comprises a separate layer 2, a following screen layer 3 and a separate layer 4, be formed on the slide unit 1, be used for magnetic head and a biasing layer 5 and a MR layer (MR element) 7 on it being installed by a separate layer 6 that constitutes by insulation or high-resistance material.Separate layer 2 is used to improve the tack between slide unit 1 and the following screen layer 3.Following screen layer 3 and last shielding device (not shown) are used to prevent that MR element 7 from detecting the magnetic field of the position in addition, position that will read from MR element 7.Separate layer 4 is carrying out the magnetic isolation between screen layer 3 and the biasing layer 5 down.Biasing layer 5 is used for a bias magnetic field is added to the MR element with predetermined direction.Be added to this magnetic field on the MR element 7 by providing electric current to produce to biasing layer 5.This bias magnetic field has the effect of the sensitivity of optimizing MR element 7.Separate layer 6 be used to make biasing layer 5 and MR element 7 each other electricity separate so that the electric current that flows through is wherein controlled.Have the magnetic domain control layer 8 that is used to reduce the Barkhausen noise on the MR element 7, be used for and be arranged on electrode 10A, the 10B of the end of MR layer 7 from the layer 9 of the angle limits track width produced.Electrode 10B links to each other with MR layer 7 by the magnetic domain control layer 8 that is used as conductor.
According to this embodiment, biasing layer 5 is used as the layer of the temperature change that is used to detect the MR head.It is 5 to 50nm thick that separate layer 6 between MR layer 7 and biasing layer 5 is approximately, and the temperature of MR layer 7 is considered to identical with the temperature cardinal principle of biasing layer 5.In order to provide electric current to MR layer 7 and biasing layer 5 respectively, be provided with electrode in the end of biasing layer 5.The shared lead-in wire of electrode 10A of electrode and MR layer 7 is to reduce the number of lead-in wire.The benefit of electric current is provided to setover layer 5 and MR layer 7 respectively, is the control of being convenient to bias current.
In this structure, biasing layer 5, MR layer 7, magnetic domain control layer 8 and electrode 10 usefulness conductive materials are made.Separate layer 6 can be formed by high-resistance metal, and the most handy nonconductive material becomes.In addition, separate layer 6 also can be made without material.Biasing layer 5 can be one the shunt bias that provides electric current to produce magnetic field by to a conductor is provided, also can be one wherein electric current be provided for the soft adjacent layer (SAL) of a soft magnetic material.Under any situation in these two kinds, biasing layer 5 all can be used as the temperature detection layer.
An example of the configuration of the circuit that is used to remove thermal fluctuation is described now in conjunction with Fig. 1.In Fig. 1, equivalent electrical circuit of MR 30 usefulness represents, and with Fig. 2 in components identical use respectively with Fig. 2 in identical label represent.
In Fig. 1, this circuit is subjected to the driving of a steady current.MR layer 7 detects magnetic signal and thermal fluctuation, and biasing layer 5 detects because change rather than the magnetic signal that thermal fluctuation causes.When a constant electric current is provided for MR layer 7 and biasing layer 5, on MR layer 7 and biasing layer 5, has observed respectively and changed corresponding voltage with resistance.The alternating component of these voltages is amplified by differential amplifier 20 and 20 ' respectively.Subsequently for different with the change speed of temperature of the electric current of corrects bias layer 5 and MR layer 7 and resistance, with amplifier 21 they regulated, and they are input to differential amplifier 22.At amplifier 22, from the signal of MR layer 7 with come the signal of automatic biasing layer 5 to obtain the difference amplification,, prevent that simultaneously the magnetic signal that MR layer 7 detects from unnecessary variation taking place to remove thermal fluctuation.
Except above-mentioned constant current driven method, also can adopt the constant voltage driving method that electric current is replaced difference and amplify.
This temperature detection layer can be set on the MR head of any kind that can constitute in various manners.In conjunction with Fig. 3 and 4, another embodiment of the present invention will be described.
Fig. 3 and 4 has shown the magnetic head of seeing from magnetic head one side that contacts with dish.Fig. 3 has shown the temperature detection layer 12 that is provided with respectively with biasing layer 5, and this temperature detection layer 12 is set under the separate layer 11 of traditional MR head.An electrode 10C is used to temperature detection layer 12, and shared by MR element 7 and 5 on biasing layer at the electrode 10A of a relative side.
Fig. 4 has shown the MR head that also comprises a temperature detection layer 12 except the element of traditional MR head (magnetic domain control layer of making such as separate layer 23 and wall 13, with insulating material 8).As under the situation of Fig. 3, the MR head comprises the electrode 10C that is used for temperature detection layer 12 and the electrode 10A shared with MR element 7.
As mentioned above, main point of the present invention is that a temperature detection layer is provided near the MR layer, and embodiment is not subjected to the restriction of structure, layout, material, processing of head or the like.
Fig. 6 has shown the general structure that comprises according to the disk unit of MR head of the present invention and thermal fluctuation compensating circuit.Be included in the R/W prime amplifier/thermal fluctuation compensator-amplifier unit 63 in conjunction with the described thermal fluctuation compensating circuit of Fig. 1.Below the concise and to the point operation of describing disk unit.MR/IND head is driven along panel surface by a voice coil motor (VCM) 62, to write or sense data on the target location on the disk 68.For data read operation, thermal fluctuation is removed from the reproduction output of MR/IND 61 by a R/W prime amplifier/thermal fluctuation compensator-amplifier unit 63.Under the corresponding situation of signal in the data field of reproducing signal after thermal fluctuation is removed and disk 68, this signal is added on R/W channel and the discriminator circuit 64 therein.Therein under the situation of this signal corresponding to the signal in the servo signal area on disk 68, it is added on the position signalling detuner 65, thereby makes a stature positioner 66 carry out the operation of following the tracks of such as searching or the road of MR/IND 61 according to this signal.
In this disk unit, thermal fluctuation is removed from the output signal of MR head.Thereby can prevent because position control maloperation and the data error that thermal fluctuation causes.
As can be seen from the foregoing description, according to the present invention, utilize the output of temperature-detecting device, the thermal fluctuation that is superimposed upon on the data-signal has been removed in real time, thereby has improved the throughput of data.In addition, even when sharp-pointed thermal fluctuation having occurred, data also can obtain suitable compensation, thereby improve the reliability of data.
In addition, though the relatively poor dish of flatness is also handled owing to the thermal fluctuation that is produced is used as defective disc with contacting of MR head is more frequent, makes it possible to use those up to the present to be considered to the dish of defective disc according to thermal fluctuation removing method of the present invention and MR head.

Claims (7)

1, a kind of magnetoresistive head, it has and is used to utilize magnetoresistance effect to detect the magnetoresistance element in magnetic field, it is characterized in that
Be used to detect the temperature-detecting device of the temperature change of magnetoresistance element; And
Be used to export the device of the information of the temperature change that is detected by described temperature-detecting device.
2, according to the magnetoresistive head of claim 1, it is characterized in that
Described temperature-detecting device is to be made by the material that has with the resistance of temperature change, and
The resistance that described output unit is exported this temperature-detecting device with the form of the signal identical with the output type of magnetoresistance element changes information.
3, according to the magnetoresistive head of claim 1, it is characterized in that
Described temperature-detecting device also plays a part to be used for a bias magnetic field is added to biasing layer on the magnetoresistance element, and
Described output unit provides electric current to this biasing layer.
4, according to the magnetoresistive head of claim 2, it is characterized in that
Described magnetoresistance element and described temperature-detecting device are electrically insulated from each other.
5, a kind of disk unit is characterized in that
A magnetoresistive head, it comprises the device of the temperature change that is used to detect a magnetoresistance element and is used to export the device of the information of this temperature change; And
Be used for removing from the output signal of magnetoresistance element the device of thermal fluctuation according to this temperature change information.
6, according to the disk unit of claim 5, it is characterized in that
The described temperature-detecting device that is used for magnetoresistive head is to be made with the material of temperature change by its resistance, and the described output unit output signal identical with the output signal type of magnetoresistance element; And
The described device that is used to remove thermal fluctuation along with the change speed of temperature and the output signal level of temperature-detecting device and magnetoresistance element compensate, and is eliminated thermal fluctuation by the difference of getting these two compensating signals to the resistance of magnetoresistance element and temperature-detecting device.
7, a kind of method that is used for eliminating from the output of magnetoresistive head thermal fluctuation is characterized in that following steps:
Detect the temperature change of a magnetoresistance element of this magnetoresistive head;
Obtain the information of this temperature change aspect independently with the output of this magnetoresistance element; And
From the output of magnetoresistance element, eliminate the influence of temperature change by the information of utilizing this temperature change aspect.
CN 94115634 1993-09-01 1994-08-31 Magnetoresistive head and magnetic disc apparatus Pending CN1109621A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP217256/93 1993-09-01
JP21725693A JPH0773417A (en) 1993-09-01 1993-09-01 Magneto-resistance effect type magnetic head and magnetic disk device

Publications (1)

Publication Number Publication Date
CN1109621A true CN1109621A (en) 1995-10-04

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CN 94115634 Pending CN1109621A (en) 1993-09-01 1994-08-31 Magnetoresistive head and magnetic disc apparatus

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JP (1) JPH0773417A (en)
CN (1) CN1109621A (en)
GB (1) GB2281654A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1296895C (en) * 2003-09-02 2007-01-24 株式会社东芝 Magnetic recording/reproducing apparatus

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2747822A1 (en) * 1996-04-17 1997-10-24 Philips Electronics Nv MAGNETIC INFORMATION READING SYSTEM WITH THERMAL ASPERITY DETECTOR
US5880899A (en) * 1997-02-25 1999-03-09 International Business Machines Corporation Removal of raised irregularities on a data storage disk with controlled abrasion by a magnetoresistive head
DE10342260B4 (en) 2003-09-11 2014-11-20 Meas Deutschland Gmbh Magnetoresistive sensor in the form of a half or full bridge circuit

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2012095A (en) * 1978-01-03 1979-07-18 Burroughs Corp Cancellation of thermal noise in magnetoresistive heads

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1296895C (en) * 2003-09-02 2007-01-24 株式会社东芝 Magnetic recording/reproducing apparatus

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Publication number Publication date
JPH0773417A (en) 1995-03-17
GB9417000D0 (en) 1994-10-19
GB2281654A (en) 1995-03-08

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