EP0829081A1 - Magnetic head with uninterrupted flux guide - Google Patents

Magnetic head with uninterrupted flux guide

Info

Publication number
EP0829081A1
EP0829081A1 EP97905357A EP97905357A EP0829081A1 EP 0829081 A1 EP0829081 A1 EP 0829081A1 EP 97905357 A EP97905357 A EP 97905357A EP 97905357 A EP97905357 A EP 97905357A EP 0829081 A1 EP0829081 A1 EP 0829081A1
Authority
EP
European Patent Office
Prior art keywords
magnetic head
magnetic
head
flux guide
multichannel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97905357A
Other languages
German (de)
French (fr)
Inventor
Jacobus Josephus Maria Ruigrok
Gerardus Henricus Johannes Somers
Hans Willem Van Kesteren
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
OnStream Inc
Original Assignee
Koninklijke Philips Electronics NV
Philips Electronics NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics NV, Philips Electronics NV filed Critical Koninklijke Philips Electronics NV
Publication of EP0829081A1 publication Critical patent/EP0829081A1/en
Withdrawn legal-status Critical Current

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
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3109—Details
    • G11B5/313—Disposition of layers
    • G11B5/3143—Disposition of layers including additional layers for improving the electromagnetic transducing properties of the basic structure, e.g. for flux coupling, guiding or shielding
    • 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
    • G11B5/54—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 with provision for moving the head into or out of its operative position or across tracks
    • G11B5/55—Track change, selection or acquisition by displacement of the head
    • G11B5/5521—Track change, selection or acquisition by displacement of the head across disk tracks
    • 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
    • G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • 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
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • 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
    • G11B5/58—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 with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B5/596—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 with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on disks
    • G11B5/59683—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 with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on disks for magnetoresistive heads
    • 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

Definitions

  • the invention relates to a magnetic head having a head face extending in a first direction in which a magnetic information medium is relatively movable with respect to the magnetic head, and in a second direction transverse to the first direction, and comprising a head structure with a transducing element having an effective dimension extending parallel to the second direction, and a flux guide extending in the second direction and in a third direction transverse to the first and the second direction and reaching as far as the head face, which flux guide can be magnetically coupled to the transducing element and has a first dimension in the second direction and a second dimension in the third direction.
  • the invention also relates to a multichannel magnetic head having a head face extending in a first direction in which a magnetic information medium is relatively movable with respect to the magnetic head, and in a second direction transverse to the first direction, and comprising a head structure having transducing elements which, viewed in the first direction, are juxtaposed, and flux guides which, viewed in the second direction, are juxtaposed and extend at least in the second direction and in a third direction transverse to the first and the second direction, and reach as far as the head face.
  • a magnetic head manufactured in thin-film technology is known from NL-A 8902884 (PHN 13.144), which magnetic head has a head face and comprises a substrate provided with a multilayer structure.
  • the multilayer structure comprises a plurality of coplanar soft-magnetic layers which are spatially separated from each other and reach as far as the head face for magnetic cooperation with a magnetic record carrier.
  • the multilayer structure is also provided with transducing elements which are magnetically coupled to said layers, i.e. magnetoresistive or inductive elements. Each transducing element has an effective portion within which changes of magnetization are detected or induced during operation.
  • the track density achievable upon writing and admissible upon reading is limited, because the known magnetic head has a limited channel density due to the presence of the configuration of magnetically conducting layers which are spaced apart.
  • Relatively complicated structuring techniques are required for structuring these layers and hence for defining a read or write channel, necessitating a given minimum distance between the layers.
  • the magnetic head according to the invention is characterized in that the flux guide has a relative magnetic permeability in the second direction, which is smaller than that in the third direction, the first dimension being larger than the second dimension and being larger than the effective dimension of die transducing element.
  • One aspect of the invention is based on the recognition that a stable magnetic head having an accurately defined read or write width can be realized in a relatively simple manner when using an uninterrupted flux guide in combination with a suitable magnetic anisotropy in the flux guide.
  • the magnetic head according to the invention has a favourable signal-to-noise ratio which, to a considerable extent, is due to the magnetic stability of the flux guide used.
  • the first dimension is preferably at least approximately twice as large as the second dimension. It has been found that an eminently defined read or write channel is feasible at a relatively low magnetic permeability of the flux guide in the second direction, preferably lower than 100, notably at a permeability which is at least a factor of 10 smaller than the magnetic permeability in the third direction.
  • a practical embodiment of the magnetic head according to the invention is characterized in that the flux guide has a relative magnetic permeability in the third direction, which is at least a factor of 25 larger than the relative permeability in the second direction.
  • the magnetic head according to the invention is a thin-film magnetic head and may be provided with an inductive transducing element or a magnetoresistive transducing element and, dependent on its usage, it may be a single write head or read head. It is alternatively possible to implement the magnetic head as a multichannel magnetic head, i.e. with several discrete channels. In each of these implementations, the magnetic head is applicable in video, data, audio or multimedia systems. Both as a write head, a read head and as a write/read head, the magnetic head is suitable for cooperation with a magnetic information or recording medium such as a magnetic tape or a magnetic disc.
  • the magnetic head according to the invention is also eminently suitable as a sensor.
  • Suitable materials for the flux guide are, for example, an NiFe alloy, an amo ⁇ hous CoNbZr alloy or nanocrystalline iron alloys such as an FeTaN alloy or an FeNbSiN alloy. It has been found that said iron alloys, such as Fe ⁇ g Ta I0 2 ⁇ 0 2 N 13 0 ⁇ ) or
  • Fe ⁇ 9 Nb 10 o ⁇ o 2 Si 2 2 ⁇ 0 3 N 109 ⁇ 1 0 have the desired anisotropic permeability from very low to very high frequencies, i.e. far below 1 kHz and far above 10 MHz.
  • the permeability may be measured in known manner on a flat film on, for example, a disc-shaped substrate.
  • the extent of anisotropy can be determined at preferably high frequencies, in which case the movement of the domain walls is sufficiently limited.
  • the magnetic head according to the invention is preferably characterized in that the flux guide is interrupted in the third direction for forming a gap which is bridged by the magnetoresistive element.
  • a practical embodiment of the magnetic according to the invention is characterized in that the first dimension of the flux guide is at least 40% larger than the effective dimension of the transducing element.
  • the stability of the magnetic head, used as a read head is found to be considerably better than that of the known read heads.
  • the invention also relates to a magnetic head which is characterized by the presence of several flux guides of the type defined, which, viewed in the first direction, are juxtaposed, each flux guide magnetically cooperating with a transducing element.
  • Each flux guide has a magnetic or relative magnetic permeability preferably in the third direction which is at least a factor of 10 larger than the magnetic, or relative magnetic permeability in the second direction.
  • the multichannel magnetic head according to the invention is characterized in that the flux guides can be magnetically coupled to at least several transducing elements and are uninterrupted in the second direction, at least one of the flux guides having a relative magnetic permeability in the second direction, which is smaller than that in the third direction.
  • One aspect of the invention is based on the recognition that the large number of individual, spaced flux guides required when using a suitable magnetic anisotropy in state-of-the-art multichannel heads can be replaced by a limited number of shared flux guides.
  • the anisotropy ensures the desired channel separations. Due to the magnetic permeability in the third direction, magnetic flux presented to the anisotropic flux guides is mainly guided in that direction. Consequently, the flux guides do not need to be structured in the second direction, which yields technological advantages because fewer and less complicated manufacturing steps are required than are necessary during manufacture of the known magnetic head.
  • a common, non-magnetic transducing gap may extend between the two flux guides, while the required channel separations are entirely created by magnetic anisotropy. Due to the simple multilayer head structure, in which there is hardly any relief, a simple structuring technology is required to manufacture the multichannel magnetic head which is of die thin-film type. It has been found that usable channel separations are feasible at a relatively low magnetic permeability of the flux guides in the second direction, preferably lower than 100, notably at a permeability which is at least a factor of 10 smaller than the magnetic permeability in me third direction.
  • the relative permeability in the second direction is chosen to be smaller with respect to the relative permeability in the third direction, the definition of the channel separations increases and higher channel densities are possible.
  • flux guides are preferred in which the relative permeability in the third direction is at least a factor of 25 larger than the relative permeability in the second direction. It has been found that the permeability in the first direction only plays a minor role due to the small dimension of the flux guides in this direction.
  • An additional, but important advantage of the use of anisotropic flux guides in the multichannel magnetic head according to the invention is that there is a small risk of unwanted movements of domain walls in the flux guides due to the fact that the flux guides are continued in the second direction, so that they have a satisfactory magnetic stability and thus do not cause any or hardly any Barkhausen noise.
  • the multichannel magnetic head according to the invention may be provided with inductive transducing elements and/or magnetoresistive transducing elements and. dependent on its usage, it may be a multichannel write head, a multichannel read head, a multichannel combined write/read head or a servohead.
  • the multichannel magnetic head is applicable in video, data, audio or multimedia systems.
  • the " multichannel magnetic head is eminently suitable for cooperation with a magnetic information or recording medium having a high track density, in which a track width is possible which is equal to the track pitch.
  • the multichannel magnetic head according to the invention has the specific advantage that spread of flux on adjacent tracks can be prevented, even at a very high track density.
  • Suitable materials for the flux guide are, for example, an NiFe alloy, an amorphous CoNbZr alloy or nanocrystalline iron alloys such as an FeTaN alloy or an FeNbSiN alloy. It has been found that said iron alloys, such as Fe ⁇ 8 Ta 102 ⁇ 0 2 N 13 0 ⁇ , u or Fe 9 Nb, 0 o ⁇ o 2 S1 2 2 ⁇ 03 N 109 ⁇ 1 0 have the desired anisotropic permeability from very low to very high frequencies, i.e. far below 1 kHz and far above 10 MHz.
  • An embodiment of the multichannel magnetic head according to the invention is characterized in that two flux guides have a relative magnetic permeability in the second direction, which is smaller than that in the third direction. In this embodiment, the previously mentioned channel separations are even better defined.
  • An embodiment of the multichannel magnetic head according to the invention is characterized in that at least one flux guide extends opposite at least several transducing elements.
  • this flux guide may be present entirely or only partly opposite a plurality of transducing elements.
  • the relevant flux guide extends preferably opposite all juxtaposed transducing elements or opposite a coherent group of transducing elements.
  • An embodiment of the multichannel magnetic head according to the invention is characterized by the presence of an electrically conducting strip extending in the second direction and having taps for forming individual inductive elements.
  • the strip may be made of a metal such as copper or gold.
  • An embodiment of the multichannel magnetic head according to the invention is characterized by the presence of a soft-magnetic strip extending in the second direction and having taps for forming individual magnetoresistive elements.
  • the strip may be made of, for example, an NiFe alloy.
  • the strip may also be made of a multilayer of NiFe, Cu and FeMn, constituting a giant magnetoresistive element of the spin-valve type. FeMn constitutes an anti ⁇ ferromagnetic (AF) layer.
  • An Ni oxide may alternatively be used for the last-mentioned layer.
  • the invention also relates to a device for storing information in and/or reading information from a magnetic information or recording medium such as a magnetic tape, a magnetic disc or a magnetic card, using a magnetic head or a multichannel magnetic head.
  • a magnetic information or recording medium such as a magnetic tape, a magnetic disc or a magnetic card
  • the device according to the invention is provided with the magnetic head according to the invention or the multichannel magnetic head according to the invention, and is also provided with means for mutually displacing the magnetic head, or the multichannel magnetic head, and the information medium.
  • Said heads may be of the magnetoresistive type for reading information, or of the inductive type for writing and/or reading information. Combined magnetoresistive/inductive heads are alternatively possible.
  • Fig. 1 is a diagrammatic cross-section of a first embodiment of the multichannel magnetic head according to the invention
  • Fig. 2 is a diagrammatic plan view of the first embodiment
  • Fig. 3 is a diagrammatic cross-section of a second embodiment of the multichannel magnetic head
  • Fig. 4 is a diagrammatic plan view of the second embodiment
  • Fig. 5 is a diagrammatic cross-section of the second embodiment, taken on the line V-V in Fig. 3
  • Fig. 6 is a diagrammatic cross-section of a third embodiment of the multichannel magnetic head
  • Fig. 7 is a diagrammatic plan view of the third embodiment
  • Fig. 8 shows diagrammatically an embodiment of the device according to the invention
  • Fig. 9 shows diagrammatically an embodiment of a magnetic tape cassette suitable for cooperation with the device shown in Fig. 8,
  • Fig. 10 is a diagrammatic cross-section of an embodiment of the magnetic head, particularly a single magnetic head, according to the invention.
  • Fig. 1 1 is a diagrammatic cross-section of the embodiment shown in Fig. 10, taken on the line XI-XI in Fig. 10.
  • the multichannel magnetic head according to the invention is a thin-film magnetic head and has a head face 1 for cooperation with a magnetic information medium, i.e. a magnetic tape 3 in this embodiment.
  • the head face 1 extends in two directions, a first direction x of which corresponds to the direction of movement of the magnetic tape 3, and a second direction y pe ⁇ endicular to the first direction x.
  • the multichannel magnetic head has a head structure which is provided with a non-magnetic substrate 5 of Al 2 O 3 /TiC and a thin-film structure in mis embodiment.
  • the thin-film structure comprises a plurality of inductive transducing elements 7 which, viewed in the first direction x, are juxtaposed or, viewed in the y direction, are located one behind the other.
  • the transducing elements 7 form part of one electrically conducting gold strip 9 extending in the second direction y and having taps 9a for forming individually controllable or measurable transducing elements.
  • the thin-film structure also comprises two uninterrupted flux guides 11 and 13 extending as far as the head face 1 and forming magnetic circuits for the transducing elements 7 located between the flux guides 11 and 13. Bodi flux guides 11 and 13 have such a magnetic anisotropy that their magnetic permeability ⁇ .
  • each flux guide 11 and 13 can be considered as a collection of integrated flux guides, the number of which corresponds to the number of transducing elements 7 and the anisotropy ensuring the desired channel separations.
  • the flux guides 11 and 13 are formed from an FeTaN alloy in this embodiment, in which the presence of the anisotropy is obtained by applying a suitable magnetic field during deposition of said material. If an NiFe alloy instead of an FeTaN alloy is used, said factor may have a value of minimally 25.
  • the magnetic permeability in this direction plays an insignificant role.
  • the flux guides 11 and 13 bound a non-magnetic transducing gap 15 adjoining the head face 1.
  • the transducing gap 15 is formed from SiO 2 , Al 2 O 3 or another non-magnetic material.
  • the multichannel magnetic head has a head face 101 extending in a first direction x, which corresponds to the longitudinal direction of a magnetic tape moving along the magnetic head during operation, and in which direction the magnetic tape 103 is movable relative to the magnetic head, and a second direction y, pe ⁇ endicular to the first direction x. which corresponds to the transverse direction of the magnetic tape 103.
  • the flux guide 111 which is provided on a non-magnetic substrate 105, is uninterrupted in the second direction y.
  • the flux guide 113a, 113b is interrupted in a third direction z pe ⁇ endicular to the directions x and y, which third direction corresponds to the direction of thickness of the magnetic tape 103, while a space or gap 114 of a non ⁇ magnetic material extends between the two flux guide parts 113a and 113b.
  • the gap 114 is bridged by a soft-magnetic strip 109 of, for example an NiFe alloy, extending in the second direction y.
  • the strip 109 is provided with taps 109a for forming the individually measurable magnetoresistive elements 107.
  • d e flux guides 111 and 113a, 113b are made of an FeNbSiN alloy and both have a relative permeability ⁇ ⁇ in the third direction z, which is many times larger, i.e. 100 to 1000 times larger, than the relative permeability ⁇ in the second direction y.
  • a soft- magnetic substrate for example of an NiZn ferrite may alternatively be used.
  • FIG. 5 the magnetic head according to the invention, shown in Figs. 3 and 4, is shown in operation.
  • a plurality of magnetic tracks 103a in which audio, video and/or data information is stored, is present on the magnetic tape 1.
  • the magnetic flux coming from the several tracks 103a is guided to the magnetoresistive elements 107 via the anisotropic flux guide 1 13a, 113b, particularly the flux guide part 113a, the flux mainly flowing in the z direction due to the presence of anisotropy.
  • Fig. 5 shows diagrammatically a slightly diverging flux guide pattern 115 occurring in the flux guide part 113a.
  • the extent of divergence, and hence the quality of the channel separations achieved, is dependent on the difference between the permeability ⁇ n and the permeability ⁇ .
  • the multichannel magnetic head is a sensor-in-gap head (SIG head).
  • a head face 201 extends in a first direction x and a second direction y, the direction x corresponding to the direction in which a magnetic information medium is relatively movable with respect to the multichannel magnetic head.
  • the multichannel magnetic head comprises a head structure which is provided with a magnetic substrate 205 functioning as a flux guide, a flux guide 213, and transducing elements, particularly magnetoresistive sensors 207, extending between the substrate 205 and the flux guide 213.
  • the transducing elements 207, the substrate 205 as well as the flux guide 213 adjoin the head face 201.
  • Insulating material 202 such as quartz, is present between the substrate 205 and the flux guide 213, between the substrate 205 and the transducing elements 207, and between the transducing elements 207 and the flux guide 213.
  • the substrate 205 and the flux guide 213 are made of an amo ⁇ hous CoNbZr alloy and extend uninterruptedly in the direction y along several transducing elements 207.
  • both the magnetic substrate 205 and the flux guide 213 have a relative permeability ⁇ n which is many times larger, at least 100 times, than the relative permeability ⁇ ,,, in the direction y.
  • the transducing elements 207 may be separate elements or, as in this embodiment, integrated elements of one strip 209 of a magnetoresistive material such as NiFe.
  • the strip 209 has taps 209a for individually measuring the transducing elements 207.
  • the invention is not limited to the multichannel magnetic heads shown.
  • the measures used may be successfully applied in various types of multichannel magnetic heads, particularly read heads, write heads and read/write heads, irrespective of the number of channels.
  • the device according to the invention is suitable for writing and/or reading a magnetic tape 603 which, in this embodiment, is present in a cassette 601 shown in Fig. 9.
  • the device has a housing 501 with a frame 503.
  • the housing 501 accommodates, inter alia, a drive motor 505 for driving a drive roll 507 and a multichannel magnetic head 511 according to the invention which is secured to a sub-frame 509 in this embodiment, which sub-frame is movable along a guide shaft 515 by means of a drive motor 513.
  • the device also has a guide 517 for sliding the cassette 601 into and out of the housing 501.
  • the cassette 601 may be used, for example, for storing information in a digital form.
  • the cassette has two take-up reels 605 and 607 between which a part of the magnetic tape 603 is present.
  • the part of the magnetic tape 603 present between the two reels is guided along two stationary tape guides 609 and 611 in this embodiment and moves along a capstan 613.
  • An endless drive belt 615 moving along the capstan 613, the reels 605 and 607 and two belt guides 617 and 619 is present in the cassette 601.
  • the magnetic head 511 engages a recess 621 in the cassette and is in contact with the magnetic tape 603.
  • the drive roll 507 is in contact with the capstan 613 via which the magnetic tape 603 is longitudinally movable from one to the other reel.
  • the device shown is a data storage device, the device according to the invention is not limited thereto.
  • the device may alternatively be an audio and/or video device.
  • the information medium may not only be a magnetic tape but also a magnetic disc or a magnetic card.
  • the magnetic head according to the invention is built up by means of a thin- film technique and has a head face 701 for cooperation with a magnetic information medium such as a magnetic tape 703.
  • the head face 701 extends in two directions, a first direction x corresponding to the direction of movement of the magnetic tape 703 and a second direction y being pe ⁇ endicular to the first direction x and corresponding to the transverse direction of the magnetic tape 703.
  • the magnetic head has a head structure which, in this embodiment, is provided with a non-magnetic substrate 705 of, for example, Al 2 O 3 /TiC on which a min-film structure is provided.
  • a thin-film structure comprises a magnetoresistive element 707 and a magnetic yoke comprising two flux guides 711 and 713a, 713b.
  • An electrically insulating non-magnetic insulation layer 710 of, for example, quartz is present between the flux guide 711 which is provided on the non-magnetic substrate 705, in which an insulation may be present or not present between the substrate 705 and the flux guide 711, and the flux guides 713a, 713b.
  • the magnetic head may be implemented without a flux guide 711. This is done, for example, when die substrate 705 is made of a magnetic material such as a ferrite, for example, NiZn ferrite and thus functions as a flux guide.
  • the flux guide 713a, 713b is interrupted in a direction z pe ⁇ endicular to the directions x and y, which direction z corresponds to the normal on the head face 701 , while a gap 714 filled with a non-magnetic material such as quartz is present between the two flux guide parts 713a, 713b.
  • the gap 714 is bridged by an insulation layer 712 and the previously mentioned magnetoresistive element 707.
  • the element 707 is constituted by a thin layer 709 of, for example, an NiFe alloy, which layer 709 is connected at end parts 709a to electrically conducting supply and return layers 709b.
  • the part of the layer 709 extending between the end parts 709a forms the effective part of the magnetoresistive element 707 with an effective dimension 1.
  • One of the flux guides 71 1 or 713a, 713b, but preferably both flux guides 71 1 and 713a, 713b have a relative permeability ⁇ ra in the third direction z which is many times larger, for example, 100-to 1000 times larger than the relative permeability ⁇ dress. in the second direction y and a dimension which is considerably larger than the effective dimension 1 of the magnetoresistive element 707 in the second direction y, while flux guide parts are present on both sides of the element 707.
  • said dimension in the second direction y is at least 40% larger than the effective dimension 1. Due to this measure, a narrow, but stable magnetic head having a transducing gap is realized in a simple manner.
  • the measure may also be used in me magnetic head unit which is provided with several magnetic heads extending side by side of the type as shown in Figs. 10 and 1 1.
  • the measure may further be used in a magnetic head in which the magnetoresistive element adjoins the head face, as is shown in Fig. 1.
  • the magnetic head according to me invention and its variants shown in Figs. 10 and 11 are particularly suitable for cooperation wim media having information tracks of small track wid ⁇ hs, for example track wid ⁇ is of less than approximately 30 microns, because the dimension of the flux guide or flux guides in the second direction is always larger than the dimension in the third direction, which has a favourable effect on the magnetic stability of the magnetic head.
  • the magnetic head shown is suitable, for example, for use in a device as shown in Fig. 8.
  • the multichannel head 511 shown in mis Figure is then replaced by the above-described magnetic head according to the invention.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Magnetic Heads (AREA)

Abstract

Multichannel magnetic head having a head face (101) extending in a first direction (x) in which a magnetic information medium is relatively movable with respect to the magnetic head, and in a second direction (y) transverse to the first direction. Viewed in the first direction, a head structure comprises juxtaposed transducing elements (107) and a flux guide (113a, 113b) extending in the second direction and in a third direction (z) transverse to the first direction (x) and the second direction (y) and reaching as far as the head face. The flux guide, which is uninterrupted in the second direction, is located opposite the transudcting elements and has a relative magnetic permeability (νry) in the second direction, which is smaller than that in the third direction, so that channel separations are formed.

Description

Magnetic head with uninterrupted flux guide.
The invention relates to a magnetic head having a head face extending in a first direction in which a magnetic information medium is relatively movable with respect to the magnetic head, and in a second direction transverse to the first direction, and comprising a head structure with a transducing element having an effective dimension extending parallel to the second direction, and a flux guide extending in the second direction and in a third direction transverse to the first and the second direction and reaching as far as the head face, which flux guide can be magnetically coupled to the transducing element and has a first dimension in the second direction and a second dimension in the third direction. The invention also relates to a multichannel magnetic head having a head face extending in a first direction in which a magnetic information medium is relatively movable with respect to the magnetic head, and in a second direction transverse to the first direction, and comprising a head structure having transducing elements which, viewed in the first direction, are juxtaposed, and flux guides which, viewed in the second direction, are juxtaposed and extend at least in the second direction and in a third direction transverse to the first and the second direction, and reach as far as the head face.
A magnetic head manufactured in thin-film technology is known from NL-A 8902884 (PHN 13.144), which magnetic head has a head face and comprises a substrate provided with a multilayer structure. The multilayer structure comprises a plurality of coplanar soft-magnetic layers which are spatially separated from each other and reach as far as the head face for magnetic cooperation with a magnetic record carrier. The multilayer structure is also provided with transducing elements which are magnetically coupled to said layers, i.e. magnetoresistive or inductive elements. Each transducing element has an effective portion within which changes of magnetization are detected or induced during operation. Although relatively narrow information tracks can be written and/or read with the known magnetic head, the track density achievable upon writing and admissible upon reading is limited, because the known magnetic head has a limited channel density due to the presence of the configuration of magnetically conducting layers which are spaced apart. Relatively complicated structuring techniques are required for structuring these layers and hence for defining a read or write channel, necessitating a given minimum distance between the layers.
It is an object of the invention to provide a magnetically stable magnetic head having a relatively narrow read or write channel and realized in a simple manner. Moreover, a high channel density is envisaged when using a multichannel magnetic head.
The magnetic head according to the invention is characterized in that the flux guide has a relative magnetic permeability in the second direction, which is smaller than that in the third direction, the first dimension being larger than the second dimension and being larger than the effective dimension of die transducing element.
One aspect of the invention is based on the recognition that a stable magnetic head having an accurately defined read or write width can be realized in a relatively simple manner when using an uninterrupted flux guide in combination with a suitable magnetic anisotropy in the flux guide. The magnetic head according to the invention has a favourable signal-to-noise ratio which, to a considerable extent, is due to the magnetic stability of the flux guide used. In a practical embodiment, the first dimension is preferably at least approximately twice as large as the second dimension. It has been found that an eminently defined read or write channel is feasible at a relatively low magnetic permeability of the flux guide in the second direction, preferably lower than 100, notably at a permeability which is at least a factor of 10 smaller than the magnetic permeability in the third direction.
A practical embodiment of the magnetic head according to the invention is characterized in that the flux guide has a relative magnetic permeability in the third direction, which is at least a factor of 25 larger than the relative permeability in the second direction.
The magnetic head according to the invention is a thin-film magnetic head and may be provided with an inductive transducing element or a magnetoresistive transducing element and, dependent on its usage, it may be a single write head or read head. It is alternatively possible to implement the magnetic head as a multichannel magnetic head, i.e. with several discrete channels. In each of these implementations, the magnetic head is applicable in video, data, audio or multimedia systems. Both as a write head, a read head and as a write/read head, the magnetic head is suitable for cooperation with a magnetic information or recording medium such as a magnetic tape or a magnetic disc. The magnetic head according to the invention is also eminently suitable as a sensor.
Suitable materials for the flux guide are, for example, an NiFe alloy, an amoφhous CoNbZr alloy or nanocrystalline iron alloys such as an FeTaN alloy or an FeNbSiN alloy. It has been found that said iron alloys, such as Fe^ gTaI0 2 ± 0 2N13 0 ± ) or
Fe^ 9Nb10 o ± o 2Si2 2 ± 0 3N109 ± 1 0 have the desired anisotropic permeability from very low to very high frequencies, i.e. far below 1 kHz and far above 10 MHz.
The permeability may be measured in known manner on a flat film on, for example, a disc-shaped substrate. For example, when using a self-induction measurement in the easy and hard axis directions, the extent of anisotropy can be determined at preferably high frequencies, in which case the movement of the domain walls is sufficiently limited.
If a magnetoresistive transducing element is provided, the magnetic head according to the invention is preferably characterized in that the flux guide is interrupted in the third direction for forming a gap which is bridged by the magnetoresistive element. A practical embodiment of the magnetic according to the invention is characterized in that the first dimension of the flux guide is at least 40% larger than the effective dimension of the transducing element. Statistically, the stability of the magnetic head, used as a read head, is found to be considerably better than that of the known read heads. The invention also relates to a magnetic head which is characterized by the presence of several flux guides of the type defined, which, viewed in the first direction, are juxtaposed, each flux guide magnetically cooperating with a transducing element.
The effects and advantages described elsewhere in this Patent Application are also applicable to this magnetic head according to the invention. Each flux guide has a magnetic or relative magnetic permeability preferably in the third direction which is at least a factor of 10 larger than the magnetic, or relative magnetic permeability in the second direction.
The multichannel magnetic head according to the invention is characterized in that the flux guides can be magnetically coupled to at least several transducing elements and are uninterrupted in the second direction, at least one of the flux guides having a relative magnetic permeability in the second direction, which is smaller than that in the third direction.
One aspect of the invention is based on the recognition that the large number of individual, spaced flux guides required when using a suitable magnetic anisotropy in state-of-the-art multichannel heads can be replaced by a limited number of shared flux guides. In the flux guides present in the multichannel magnetic head according to the invention, the anisotropy ensures the desired channel separations. Due to the magnetic permeability in the third direction, magnetic flux presented to the anisotropic flux guides is mainly guided in that direction. Consequently, the flux guides do not need to be structured in the second direction, which yields technological advantages because fewer and less complicated manufacturing steps are required than are necessary during manufacture of the known magnetic head.
In the multichannel magnetic head according to the invention, in which each flux guide is uninterrupted in the second direction, a common, non-magnetic transducing gap may extend between the two flux guides, while the required channel separations are entirely created by magnetic anisotropy. Due to the simple multilayer head structure, in which there is hardly any relief, a simple structuring technology is required to manufacture the multichannel magnetic head which is of die thin-film type. It has been found that usable channel separations are feasible at a relatively low magnetic permeability of the flux guides in the second direction, preferably lower than 100, notably at a permeability which is at least a factor of 10 smaller than the magnetic permeability in me third direction.
As the relative permeability in the second direction is chosen to be smaller with respect to the relative permeability in the third direction, the definition of the channel separations increases and higher channel densities are possible. In a practical embodiment, flux guides are preferred in which the relative permeability in the third direction is at least a factor of 25 larger than the relative permeability in the second direction. It has been found that the permeability in the first direction only plays a minor role due to the small dimension of the flux guides in this direction. An additional, but important advantage of the use of anisotropic flux guides in the multichannel magnetic head according to the invention is that there is a small risk of unwanted movements of domain walls in the flux guides due to the fact that the flux guides are continued in the second direction, so that they have a satisfactory magnetic stability and thus do not cause any or hardly any Barkhausen noise.
The multichannel magnetic head according to the invention may be provided with inductive transducing elements and/or magnetoresistive transducing elements and. dependent on its usage, it may be a multichannel write head, a multichannel read head, a multichannel combined write/read head or a servohead. In each of these implementations, the multichannel magnetic head is applicable in video, data, audio or multimedia systems. Both as a write head and as a read head, the" multichannel magnetic head is eminently suitable for cooperation with a magnetic information or recording medium having a high track density, in which a track width is possible which is equal to the track pitch. As a write head, the multichannel magnetic head according to the invention has the specific advantage that spread of flux on adjacent tracks can be prevented, even at a very high track density.
Suitable materials for the flux guide are, for example, an NiFe alloy, an amorphous CoNbZr alloy or nanocrystalline iron alloys such as an FeTaN alloy or an FeNbSiN alloy. It has been found that said iron alloys, such as Fe^ 8Ta102 ± 0 2N13 0 ± , u or Fe 9Nb,0 o ± o 2S12 2 ± 03N109 ± 10 have the desired anisotropic permeability from very low to very high frequencies, i.e. far below 1 kHz and far above 10 MHz.
An embodiment of the multichannel magnetic head according to the invention is characterized in that two flux guides have a relative magnetic permeability in the second direction, which is smaller than that in the third direction. In this embodiment, the previously mentioned channel separations are even better defined.
An embodiment of the multichannel magnetic head according to the invention is characterized in that at least one flux guide extends opposite at least several transducing elements. Dependent on the implementation, this flux guide may be present entirely or only partly opposite a plurality of transducing elements. The relevant flux guide extends preferably opposite all juxtaposed transducing elements or opposite a coherent group of transducing elements.
An embodiment of the multichannel magnetic head according to the invention is characterized by the presence of an electrically conducting strip extending in the second direction and having taps for forming individual inductive elements. Such a configuration of inductive elements is space-saving and may be realized during manufacture by means of known techniques. The strip may be made of a metal such as copper or gold.
An embodiment of the multichannel magnetic head according to the invention is characterized by the presence of a soft-magnetic strip extending in the second direction and having taps for forming individual magnetoresistive elements. Such a configuration of magnetoresistive elements is space-saving and may be realized during manufacture by means of known techniques. The strip may be made of, for example, an NiFe alloy. The strip may also be made of a multilayer of NiFe, Cu and FeMn, constituting a giant magnetoresistive element of the spin-valve type. FeMn constitutes an anti¬ ferromagnetic (AF) layer. An Ni oxide may alternatively be used for the last-mentioned layer.
The invention also relates to a device for storing information in and/or reading information from a magnetic information or recording medium such as a magnetic tape, a magnetic disc or a magnetic card, using a magnetic head or a multichannel magnetic head.
The device according to the invention is provided with the magnetic head according to the invention or the multichannel magnetic head according to the invention, and is also provided with means for mutually displacing the magnetic head, or the multichannel magnetic head, and the information medium. Said heads may be of the magnetoresistive type for reading information, or of the inductive type for writing and/or reading information. Combined magnetoresistive/inductive heads are alternatively possible.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.
In the drawings:
Fig. 1 is a diagrammatic cross-section of a first embodiment of the multichannel magnetic head according to the invention,
Fig. 2 is a diagrammatic plan view of the first embodiment, Fig. 3 is a diagrammatic cross-section of a second embodiment of the multichannel magnetic head,
Fig. 4 is a diagrammatic plan view of the second embodiment,
Fig. 5 is a diagrammatic cross-section of the second embodiment, taken on the line V-V in Fig. 3, Fig. 6 is a diagrammatic cross-section of a third embodiment of the multichannel magnetic head,
Fig. 7 is a diagrammatic plan view of the third embodiment,
Fig. 8 shows diagrammatically an embodiment of the device according to the invention, Fig. 9 shows diagrammatically an embodiment of a magnetic tape cassette suitable for cooperation with the device shown in Fig. 8,
Fig. 10 is a diagrammatic cross-section of an embodiment of the magnetic head, particularly a single magnetic head, according to the invention, and
Fig. 1 1 is a diagrammatic cross-section of the embodiment shown in Fig. 10, taken on the line XI-XI in Fig. 10.
The multichannel magnetic head according to the invention, shown in Figs. 1 and 2, is a thin-film magnetic head and has a head face 1 for cooperation with a magnetic information medium, i.e. a magnetic tape 3 in this embodiment. The head face 1 extends in two directions, a first direction x of which corresponds to the direction of movement of the magnetic tape 3, and a second direction y peφendicular to the first direction x. The multichannel magnetic head has a head structure which is provided with a non-magnetic substrate 5 of Al2O3/TiC and a thin-film structure in mis embodiment. The thin-film structure comprises a plurality of inductive transducing elements 7 which, viewed in the first direction x, are juxtaposed or, viewed in the y direction, are located one behind the other. In this embodiment, the transducing elements 7 form part of one electrically conducting gold strip 9 extending in the second direction y and having taps 9a for forming individually controllable or measurable transducing elements. The thin-film structure also comprises two uninterrupted flux guides 11 and 13 extending as far as the head face 1 and forming magnetic circuits for the transducing elements 7 located between the flux guides 11 and 13. Bodi flux guides 11 and 13 have such a magnetic anisotropy that their magnetic permeability μ. in a third direction z, which is peφendicular to the directions x and y, is a factor of 100 or more larger than their magnetic permeability μ^ in the second direction y. Due to the anisotropy used, each flux guide 11 and 13 can be considered as a collection of integrated flux guides, the number of which corresponds to the number of transducing elements 7 and the anisotropy ensuring the desired channel separations. The flux guides 11 and 13 are formed from an FeTaN alloy in this embodiment, in which the presence of the anisotropy is obtained by applying a suitable magnetic field during deposition of said material. If an NiFe alloy instead of an FeTaN alloy is used, said factor may have a value of minimally 25.
For example, sputtering may be used as a deposition method. It is to be noted that, due to the small thickness of the flux guides 11 and 13 in the first direction x, the magnetic permeability in this direction plays an insignificant role. It is also to be noted that the flux guides 11 and 13 bound a non-magnetic transducing gap 15 adjoining the head face 1. Similarly as the insulation layers present between the strip 9 and the flux guides 1 1 and 13, the transducing gap 15 is formed from SiO2, Al2O3 or another non-magnetic material. The multichannel magnetic head according to the invention, shown in Figs. 3 and 4, is an YMR head in which magnetic yokes are formed by a first flux guide 111 , a second flux guide 1 13a, 113b and transducing elements 107 of the magnetoresistive type. The multichannel magnetic head has a head face 101 extending in a first direction x, which corresponds to the longitudinal direction of a magnetic tape moving along the magnetic head during operation, and in which direction the magnetic tape 103 is movable relative to the magnetic head, and a second direction y, peφendicular to the first direction x. which corresponds to the transverse direction of the magnetic tape 103. Similarly as the flux guide 113a, 113b, the flux guide 111, which is provided on a non-magnetic substrate 105, is uninterrupted in the second direction y. However, the flux guide 113a, 113b is interrupted in a third direction z peφendicular to the directions x and y, which third direction corresponds to the direction of thickness of the magnetic tape 103, while a space or gap 114 of a non¬ magnetic material extends between the two flux guide parts 113a and 113b. The gap 114 is bridged by a soft-magnetic strip 109 of, for example an NiFe alloy, extending in the second direction y. The strip 109 is provided with taps 109a for forming the individually measurable magnetoresistive elements 107.
In this embodiment, d e flux guides 111 and 113a, 113b are made of an FeNbSiN alloy and both have a relative permeability μπ in the third direction z, which is many times larger, i.e. 100 to 1000 times larger, than the relative permeability μ^ in the second direction y. Instead of the non-magnetic substrate 105 and the flux guide 111, a soft- magnetic substrate, for example of an NiZn ferrite may alternatively be used.
In Fig. 5, the magnetic head according to the invention, shown in Figs. 3 and 4, is shown in operation. A plurality of magnetic tracks 103a, in which audio, video and/or data information is stored, is present on the magnetic tape 1. The magnetic flux coming from the several tracks 103a is guided to the magnetoresistive elements 107 via the anisotropic flux guide 1 13a, 113b, particularly the flux guide part 113a, the flux mainly flowing in the z direction due to the presence of anisotropy. Fig. 5 shows diagrammatically a slightly diverging flux guide pattern 115 occurring in the flux guide part 113a. The extent of divergence, and hence the quality of the channel separations achieved, is dependent on the difference between the permeability μn and the permeability μ^. The larger μπ is with respect to μ^, the smaller the divergence and the shaφer the channel separations. In this way, high channel densities are achievable, so that closely juxtaposed magnetic tracks can be scanned.
The multichannel magnetic head according to the invention, shown in Figs. 6 and 7, is a sensor-in-gap head (SIG head). Related to an orthogonal system of axes, a head face 201 extends in a first direction x and a second direction y, the direction x corresponding to the direction in which a magnetic information medium is relatively movable with respect to the multichannel magnetic head. The multichannel magnetic head comprises a head structure which is provided with a magnetic substrate 205 functioning as a flux guide, a flux guide 213, and transducing elements, particularly magnetoresistive sensors 207, extending between the substrate 205 and the flux guide 213. The transducing elements 207, the substrate 205 as well as the flux guide 213 adjoin the head face 201. Insulating material 202, such as quartz, is present between the substrate 205 and the flux guide 213, between the substrate 205 and the transducing elements 207, and between the transducing elements 207 and the flux guide 213. In this embodiment, the substrate 205 and the flux guide 213 are made of an amoφhous CoNbZr alloy and extend uninterruptedly in the direction y along several transducing elements 207. In a third direction z related to said system of axes, both the magnetic substrate 205 and the flux guide 213 have a relative permeability μn which is many times larger, at least 100 times, than the relative permeability μ,,, in the direction y. The transducing elements 207 may be separate elements or, as in this embodiment, integrated elements of one strip 209 of a magnetoresistive material such as NiFe. The strip 209 has taps 209a for individually measuring the transducing elements 207.
The invention is not limited to the multichannel magnetic heads shown. The measures used may be successfully applied in various types of multichannel magnetic heads, particularly read heads, write heads and read/write heads, irrespective of the number of channels.
The device according to the invention, shown in Fig. 8, is suitable for writing and/or reading a magnetic tape 603 which, in this embodiment, is present in a cassette 601 shown in Fig. 9. The device has a housing 501 with a frame 503. The housing 501 accommodates, inter alia, a drive motor 505 for driving a drive roll 507 and a multichannel magnetic head 511 according to the invention which is secured to a sub-frame 509 in this embodiment, which sub-frame is movable along a guide shaft 515 by means of a drive motor 513. The device also has a guide 517 for sliding the cassette 601 into and out of the housing 501. The cassette 601 may be used, for example, for storing information in a digital form. The cassette has two take-up reels 605 and 607 between which a part of the magnetic tape 603 is present. The part of the magnetic tape 603 present between the two reels is guided along two stationary tape guides 609 and 611 in this embodiment and moves along a capstan 613. An endless drive belt 615 moving along the capstan 613, the reels 605 and 607 and two belt guides 617 and 619 is present in the cassette 601. In a state of operation, in which the cassette 601 -cooperates with the device 501 according to the invention, the magnetic head 511 engages a recess 621 in the cassette and is in contact with the magnetic tape 603. Simultaneously, the drive roll 507 is in contact with the capstan 613 via which the magnetic tape 603 is longitudinally movable from one to the other reel. Aldiough, in principle, the device shown is a data storage device, the device according to the invention is not limited thereto. The device may alternatively be an audio and/or video device. Moreover, the information medium may not only be a magnetic tape but also a magnetic disc or a magnetic card.
The magnetic head according to the invention, shown in Figs. 10 and 11 , is built up by means of a thin- film technique and has a head face 701 for cooperation with a magnetic information medium such as a magnetic tape 703. The head face 701 extends in two directions, a first direction x corresponding to the direction of movement of the magnetic tape 703 and a second direction y being peφendicular to the first direction x and corresponding to the transverse direction of the magnetic tape 703. The magnetic head has a head structure which, in this embodiment, is provided with a non-magnetic substrate 705 of, for example, Al2O3/TiC on which a min-film structure is provided. A thin-film structure comprises a magnetoresistive element 707 and a magnetic yoke comprising two flux guides 711 and 713a, 713b. An electrically insulating non-magnetic insulation layer 710 of, for example, quartz is present between the flux guide 711 which is provided on the non-magnetic substrate 705, in which an insulation may be present or not present between the substrate 705 and the flux guide 711, and the flux guides 713a, 713b. If desired, the magnetic head may be implemented without a flux guide 711. This is done, for example, when die substrate 705 is made of a magnetic material such as a ferrite, for example, NiZn ferrite and thus functions as a flux guide. The flux guide 713a, 713b is interrupted in a direction z peφendicular to the directions x and y, which direction z corresponds to the normal on the head face 701 , while a gap 714 filled with a non-magnetic material such as quartz is present between the two flux guide parts 713a, 713b. The gap 714 is bridged by an insulation layer 712 and the previously mentioned magnetoresistive element 707. The element 707 is constituted by a thin layer 709 of, for example, an NiFe alloy, which layer 709 is connected at end parts 709a to electrically conducting supply and return layers 709b. The part of the layer 709 extending between the end parts 709a forms the effective part of the magnetoresistive element 707 with an effective dimension 1.
One of the flux guides 71 1 or 713a, 713b, but preferably both flux guides 71 1 and 713a, 713b have a relative permeability μra in the third direction z which is many times larger, for example, 100-to 1000 times larger than the relative permeability μ„. in the second direction y and a dimension which is considerably larger than the effective dimension 1 of the magnetoresistive element 707 in the second direction y, while flux guide parts are present on both sides of the element 707. In this embodiment, said dimension in the second direction y is at least 40% larger than the effective dimension 1. Due to this measure, a narrow, but stable magnetic head having a transducing gap is realized in a simple manner. The measure may also be used in me magnetic head unit which is provided with several magnetic heads extending side by side of the type as shown in Figs. 10 and 1 1. The measure may further be used in a magnetic head in which the magnetoresistive element adjoins the head face, as is shown in Fig. 1.
The magnetic head according to me invention and its variants shown in Figs. 10 and 11 are particularly suitable for cooperation wim media having information tracks of small track widϋhs, for example track widύis of less than approximately 30 microns, because the dimension of the flux guide or flux guides in the second direction is always larger than the dimension in the third direction, which has a favourable effect on the magnetic stability of the magnetic head. The magnetic head shown is suitable, for example, for use in a device as shown in Fig. 8. The multichannel head 511 shown in mis Figure is then replaced by the above-described magnetic head according to the invention.

Claims

CLAIMS:
1. A magnetic head having a head face extending in a first direction in which a magnetic information medium is relatively movable with respect to the magnetic head, and in a second direction transverse to the first direction, and comprising a head structure with a transducing element having an effective dimension extending parallel to the second direction, and a flux guide extending in the second direction and in a third direction transverse to die first and the second direction and reaching as far as the head face, which flux guide can be magnetically coupled to the transducing element and has a first dimension in the second direction and a second dimension in the third direction, characterized in d at the flux guide has a relative magnetic permeability in the second direction, which is smaller than that in the third direction, die first dimension being larger than the second dimension and being larger than die effective dimension of the transducing element.
2. A magnetic head as claimed in Claim 1, characterized in that the first dimension is at least approximately twice as large as the second dimension.
3. A magnetic head as claimed in Claim 1 or 2, characterized in that the flux guide has a relative magnetic permeability in the third direction, which is at least a factor of 25 larger than the relative permeability in the second direction.
4. A magnetic head as claimed in Claim 1, 2 or 3, characterized in that the transducing element is an inductive element.
5. A magnetic head as claimed in Claim 1, 2 or 3, characterized in that the transducing element is a magnetoresistive element.
6. A magnetic head as claimed in Claim 5, characterized in mat the flux guide is interrupted in the third direction for forming a gap which is bridged by the magnetoresistive element.
7. A magnetic head as claimed in any one of the preceding Claims, characterized in that the first dimension of the flux guide is at least 40% larger than the effective dimension of the transducing element.
8. A magnetic head as claimed in any one of Claims 1 to 7, characterized by the presence of several flux guides which, viewed in the first direction, are juxtaposed, each flux guide being implemented as the flux guide as claimed in any one of Claims 1 to 7, and magnetically cooperating with ar transducing element.
9. A multichannel magnetic head having a head face extending in a first direction in which a magnetic information medium is relatively movable with respect to the magnetic head, and in a second direction transverse to the first direction, and compπsing a head structure having transducing elements which, viewed in the first direction, are juxtaposed, and flux guides which, viewed in the second direction, are juxtaposed and extend in the second direction and in a third direction transverse to the first and the second direction, and reach as far as the head face, characterized in that the flux guides can be magnetically coupled to at least several transducing elements and are uninterrupted in the second direction, at least one of the flux guides having a relative magnetic permeability in the second direction, which is smaller than that in the third direction.
10. A multichannel magnetic head as claimed in Claim 9, characterized in that two flux guides have a relative magnetic permeability in the second direction, which is smaller than mat in the third direction.
11. A multichannel magnetic head as claimed in Claim 9 or 10, characterized in that at least one flux guide extends opposite at least several transducing elements.
12. A multichannel magnetic head as claimed in Claim 9, 10, 11 , characterized in that the relative magnetic permeability in the third direction is at least a factor of 25 larger than the relative permeability in me second direction.
13. A multichannel magnetic head as claimed in Claim 9, 10, 1 1 or 12, characterized in mat the transducing elements are inductive elements.
14. A multichannel magnetic head as claimed in Claim 13, characterized by the presence of an electrically conducting strip extending in the second direction and having taps for forming individual inductive elements.
15. A multichannel magnetic head as claimed in Claim 9, 10, 1 1 or 12, characterized in that the transducing elements are magnetoresistive elements.
16. A multichannel magnetic head as claimed in Claim 15, characterized by the presence of a soft-magnetic strip extending in the second direction and having taps for forming individual magnetoresistive elements.
17. A device for storing information in and/or reading information from a magnetic information medium, comprising the magnetic head as claimed in any one of the preceding Claims 1 to 8 or the multichannel magnetic head as claimed in any one of the preceding Claims 9 to 16, and means for mutually displacing the magnetic head, or the multichannel magnetic head, and me information medium.
EP97905357A 1996-03-27 1997-03-14 Magnetic head with uninterrupted flux guide Withdrawn EP0829081A1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
EP96200828 1996-03-27
NL9620082 1996-03-27
EP96203031 1996-10-30
NL9620303 1996-10-30
PCT/IB1997/000258 WO1997036289A1 (en) 1996-03-27 1997-03-14 Magnetic head with uninterrupted flux guide

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JP2000067417A (en) 1998-07-31 2000-03-03 Koninkl Philips Electronics Nv Thin film magnetic head device
EP0989547A3 (en) * 1998-07-31 2005-09-28 Koninklijke Philips Electronics N.V. "Thin-film magnetic head device"

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NL8802960A (en) * 1988-12-01 1990-07-02 Philips Nv A system comprising a magnetic head and a movable magnetic data carrier, as well as a magnetic head and a magnetic data carrier suitable for use in the system.
EP0600549B1 (en) * 1992-12-01 1999-05-12 Koninklijke Philips Electronics N.V. Method of manufacturing a thin-film magnetic head and head obtained by the method
BE1007775A3 (en) * 1993-11-22 1995-10-17 Philips Electronics Nv MAGNETIC HEAD, PROVIDED WITH A HEAD SURFACE AND A THIN FILM STRUCTURE, AND METHOD FOR MANUFACTURING THE MAGNETIC HEAD.

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