EP0167570A1 - Milieu d'enregistrement magnetique et appareil et procede pour suivre une piste de celui-ci - Google Patents

Milieu d'enregistrement magnetique et appareil et procede pour suivre une piste de celui-ci

Info

Publication number
EP0167570A1
EP0167570A1 EP85900434A EP85900434A EP0167570A1 EP 0167570 A1 EP0167570 A1 EP 0167570A1 EP 85900434 A EP85900434 A EP 85900434A EP 85900434 A EP85900434 A EP 85900434A EP 0167570 A1 EP0167570 A1 EP 0167570A1
Authority
EP
European Patent Office
Prior art keywords
light
read
record medium
write head
guidelines
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Withdrawn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
EP85900434A
Other languages
German (de)
English (en)
Inventor
Ronald Leigh Barnes
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.)
NCR Voyix Corp
Original Assignee
NCR Corp
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 NCR Corp filed Critical NCR Corp
Publication of EP0167570A1 publication Critical patent/EP0167570A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B13/00—Recording simultaneously or selectively by methods covered by different main groups among G11B3/00, G11B5/00, G11B7/00 and G11B9/00; Record carriers therefor not otherwise provided for; Reproducing therefrom not otherwise provided for
    • G11B13/04—Recording simultaneously or selectively by methods covered by different main groups among G11B3/00, G11B5/00, G11B7/00 and G11B9/00; Record carriers therefor not otherwise provided for; Reproducing therefrom not otherwise provided for magnetically or by magnetisation and optically or by radiation, for changing or sensing optical properties
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
    • G11B23/38—Visual features other than those contained in record tracks or represented by sprocket holes the visual signals being auxiliary signals
    • G11B23/42—Marks for indexing, speed-controlling, synchronising, or timing
    • 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
    • G11B5/59677—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 with optical servo tracking

Definitions

  • the present invention relates to a magnetic record medium and to an apparatus having a read/write head for magnetically reading data from, or writing data on, said medium.
  • the invention relates to a magnetic disk carrying a plurality of data tracks thereon, and to an apparatus and method for tracking a specified track on the magnetic disk.
  • a problem arising with magnetic disks carrying a large amount of information in densely packed magnetic tracks is that it is rather difficult to ensure proper positioning of the read/write head to a desired track and to ensure accurate tracking once the selected track has been found.
  • a flexible magnetic disk memory system in which the magnetic disk includes alternate data sectors and positioning sectors for recording data information and positioning information respectively. Holes are punched in the magnetic disk and arranged such that when light shines through the hole to a light sensor in the disk drive, the positioning sectors are located under a read/write head in the disk drive, and cir ⁇ cuitry is included to locate the read/write head over a specified data track during the time that the posi ⁇ tioning sector is under the read/write head. Data from the corresponding data track is then retrieved from the magnetic disk memory from that data track during the time that the data sector of the magnetic disk memory is passing under the read/write head.
  • a "Winchester* magnetic disk drive in which both data and servo track information is magnetically recorded on the magnetic disk of the drive.
  • Read/write heads and a servo head are provided for separately reading the magnetic information recorded on the disk, and a servo positioning mechanism is included to position the read/write heads over a specified data track responsive to servo track information read by the servo head.
  • a magnetic shield is provided to prevent interference between data signals and servo track position signals.
  • a disadvantage of the above described arrangements is that data information and positioning information occupy different surface areas of the disk, whereby the space available for data information is greatly reduced.
  • a magnetic record medium for use with an apparatus having a read/write head for magnetically reading data from, or writing data on, said medium, which medium includes a substrate and magnetic materi ⁇ al disposed on said substrate for carrying a plurality of data tracks thereon, characterized by a plurality of optical guidelines recorded on said record medium, one guideline being associated with each data track, said guidelines being useable by said apparatus for positioning said read/write head adjacent a selected one of said guidelines and for tracking the said guideline.
  • a method of positioning a read/write head adjacent a record medium for reading or writing data thereon characterized by the steps of placing optical guidelines on said record medium; illuminating said optical guidelines with light source means; detecting light reflecting from one of said optical guidelines; positioning said read/write head over the record medium in read/write relationship with a selected one of a plurality of data tracks on the record medium in response to the detection of the reflected light; and magnetically reading and writing data on one of a plurality of data tracks on the record medium wherein each of the data tracks is associated with one of said optical guidelines.
  • the magnetic record medium is a disk having said optical guidelines in the form of concentric circles thereon.
  • Each guideline may be intermittently inter- rupted to provide line segments of different lengths representing a code which identifies the respective guideline and the magnetic track associated therewith.
  • Fig. 1 is an illustration of a magnetic disk and a read/write head in a disk drive of the present invention
  • Fig. 2 is a partial cross-sectional view of the disk and read/write head of Fig. 1 taken along lines 2-2;
  • Fig. 3 is an illustration of a portion of a single guideline optically recorded on the disk of Fig. 1 and Fig. 2;
  • Fig. 4 presents a block diagram of a disk" drive utilizing one embodiment of the present inven- tion
  • Fig. 5 is a plot of the light intensity reflected from a guideline optically recorded on the disk of the present invention
  • Fig. 6 is a cross-sectional view of another embodiment of a lightpipe usable in the light detector system of the present invention.
  • Figs. 7-10 are other embodiments of a portion of the optical system usable with the present inven ⁇ tion for illuminating and viewing the optical guide ⁇ lines.
  • Fig. 1 is an illustration of a magnetic disk and a read/write head of a disk drive utilizing the present invention.
  • the illustrated disk 10 may be one of a number of recording media upon which data may be recorded, and is in the illustrated embodiment a magnetic disk usable in a "Winchester” disk drive, well-known in the art.
  • the disk 10 is rotated very rapidly about its central hub 12 to "fly" the disk under a read/write head 14 in an aerodynamic- ally stable condition such that data may be magneti ⁇ cally written on or read from the disk.
  • This tech ⁇ nique is well-known in the art and will not be further described.
  • the read/write head 14 includes a magnetic element 16 for reading or writing data on the disk 10, and includes a lead 18 for transmitting the data electronically as is known.
  • the disk 10 has recorded on its surface a series of optical guidelines 20 which are usable, as will be explained, to position the read/write head 14 over a desired track of magnetical ⁇ ly recorded data on the disk 10.
  • the guidelines 20 which form concentric rings around the disk 10, are approximately 5 microns wide and are spaced in a density of approximately 5,000 per inch.
  • Each guide- line 20 is periodically interrupted as at 22 in such a manner as to contain an individual code for each guideline.
  • each guideline 20 serves to be used by the read/write head 14 to position the read/write head over a .desired track of data, but the coding contained in each guideline 20 identifies the data track to which data is being written, or from which data is being read.
  • the disk drive may contain a plurality of disks stacked vertically one above the other and rotated simultaneously about the hub, as is well-known in the art. In that event, a like number of read/write heads will be positioned adjacent the recording surfaces of the disks, and electronic means will be included in the disk drive to read data from any desired track from any one of the disks in the stack. Also, in a system having a plurality of disks, each read/write head contains an optical system for detecting optical guidelines recorded on each of the disks in the system.
  • the read/write head 14 includes an optical system 24 for detecting the guidelines 20.
  • a light source such as clad illumination fibers, is provided to illuminate the surface of the disk 10, and an optical lightpipe, for instance a graded index fiber, 28 is provided for transmitting optical data to a proper detection circuit, as will be explained.
  • an optical lightpipe for instance a graded index fiber, 28 is provided for transmitting optical data to a proper detection circuit, as will be explained.
  • the guidelines 20 and the detector therefor may be for radiation of any wavelength, and is not to be limited to the visual spectrum of light.
  • Fig. 2 is an illustration of a portion of the read/write head 14 and the magnetic disk 10 taken along line 2-2 of Fig. 1.
  • the magnetic disk 10 in ⁇ cludes an aluminum substrate 30 on which the optical guidelines 20 hav been recorded.
  • the optical guide ⁇ lines are formed by recording alternate light and dark concentric circles on the aluminum substrate 30.
  • the light portions 32 in the preferred embodiment are sensed by the optical system 24 by light reflection as will be described. It will be understood that the dark portions 34 could optionally be used by a suit- able detection means instead of the light portions 32 as used herein.
  • a layer of magnetic recording materi ⁇ al 36 is deposited over the recorded guidelines as shown, and a suitable protective coating layer 38 is provided over the entire surface of the disk 10. It will be understood that the protective layer 38 and the magnetic recording material layer 36 must be sufficiently transparent to allow easy detection of the recorded guidelines 20. In the case of certain magnetic recording material which is opaque, the guidelines 20 can alternately be recorded on the surface of the disk, as may be required. Even though the system shown in Figs. 2 and 4 shows the optical system 24 arranged to read optical guidelines 20 on the same side of the disk 10 as the magnetically recorded data, the optical system 24 may be arranged such that the optical guidelines 20 are recorded on and read from the reverse side of the disk from the magnetically recorded
  • the optical system 24 extends through the read/write head 14 providing an optical path there ⁇ through, and includes the lightpipe 28 positioned axially through the center of the optical system 24 as shown.
  • the individual fibers of the illumination fibers 26 are distributed such as at 40 to be evenly positioned around the end 42 of the detector lightpipe 28 as shown.
  • the illumination fibers 26 thus arranged provide an even illumination about the periphery of the lightpipe end 42, which illumination is transmitted downwardly onto the sur ⁇ face of the disk 10 to evenly . illuminate the light portions 32 of the guideline 20 directly under the lightpipe 28.
  • the ends of the light fibers 26 and the end 42 of the lightpipe 28 may be shaped and polished to focus the light on the surface of the disk 10.
  • the light beam 46 re ⁇ flected from an individual guideline 20 is focused on a spot approximately 5 microns in diameter such that when the read/write head is properly positioned over a guideline 20, the spot upon which the reflected light beam 46 is focused will be completely contained within the width of the light portions 32 of a single guideline 20.
  • a conventional magnetic read/write element 16 is placed in the head 14 for magnetically writing to and reading from the disk 10.
  • the read/write head 14 is placed a sufficient distance above the "flying" magnetic disk that magnetic lines of flux 50 form a magnetic circuit between the magnet- ic recording material layer 36 and the magnetic ele ⁇ ment 16 to access data recorded therein as controlled by proper electronic signals over line 18.
  • the func ⁇ tion of the magnetic element 16 and the magnetic reading and recording of data is conventional and well-understood in the art, and will not be explained further herein.
  • each guideline 20 is formed by the light reflecting portion 32 recorded on the surface of the magnetic disk 10, and is bordered by dark portions 34.
  • the disk 10 is moved past the read/write head 14 as shown by the arrow 52.
  • the spot 54 is the spot previously mentioned upon which the reflected light beam 46 of Fig. 2 is focused.
  • the read/write head 14 is positioned to locate the spot 54 entirely within the light por ⁇ tion 32 of the guideline 20.
  • the read/write head as moved in either the radially inward or outward direc ⁇ tion as shown by double headed arrow 56 in Figs. 2, 3, 4 and 6.
  • the read/write head 14 is positioned over a disk 10 for magnetically reading and writing data recorded thereon as previously de ⁇ scribed from appropriate electronic data circuitry 59 in the disk drive in a conventional manner.
  • the positioning of the read/write head 14 in the radial direction, as shown by arrow 56, is accom ⁇ plished by a conventional servo mechanism including a servo motor 60 and a servo control circuit 62.
  • a light source such as a laser or a light emitting diode (LED) source 63 is provided which directs light through an illumination conduit 64 to provide illumi- nation on the surface of the magnetic disk 10.
  • the illumination source 63 is powered by an appropriate illumination power circuit 66 , dependent upon the type of light source 63 that is used.
  • the illumina ⁇ tion conduit 64 may be composed of fibers arranged similar to those of Fig. 2, or may extend directly through the read/write head 14 and be terminated by a lens 66 which focuses illumination on the surface of the disk 10 such that light reflected from a guideline 20 is directed into the detector lightpipe 70 in the same manner as discussed in connection with Fig. 2..
  • the lightpipe 70 may be a graded index fiber as dis ⁇ cussed in connection with lightpipe 28 of Fig. 2.
  • the optical path from the lightpipe 70 to a detector circuit may be any one of a number of known arrange- ments, and is shown diagrammatically as a mirror 72 which reflects light 74 from the lightpipe 70 to an optical detector 76.
  • the optical detector 76 may be any one of a number of photodetectors known in the art which pro- Jerusalem an electrical signal responsive to being struck by light.
  • the photodetector 76 features a pair of detector units 80 and 82.
  • the detector unit 80 is connected by conductor 84 to an amplifier 86 which is • in turn connected to the servo control circuit 62.
  • the detector unit 82 is connected by a conductor 88 to an amplifier 90 which is also connected to the servo control circuit 62.
  • the electrical signal coming from amplifier 86 is compared to the electrical signal coming from amplifier 90 to give an error signal which is used in a conventional manner by the servo control circuit 62 to transmit correction signals over conduc ⁇ tor 92 to the servo motor 60 to make adjustments in the positioning of the read/write head 14.
  • the detector unit 80 is connected to a summing circuit 94 by a conductor 96 , and the detector element 82 is connected to the summing circuit 94 by a conductor 98.
  • the output of summing circuit 94 is fed to a decoding circuit 100 which decodes the inter it- tent portions 22 of the guideline 20 shown in Fig. 1, for determining which guideline the read/write head 14 is positioned over.
  • the track identification of the track being read is fed to the servo control circuit 62 by conduc- tor 102 as shown.
  • a desired track identification is also supplied to the servo control circuit 62 from the magnetic disk circuitry or an appropriate computer processor over a conductor 104 for comparison with the track identification supplied by track decoding cir- cuit 100. If the track identification from conductor 102 and 104 are not identical, or a new desired track identification is received over conductor 104, the servo control circuit 62 generates appropriate control signals over conductor 92 to the servo motor 60 to reposition the read/write head 14 over the desired track. The electrical signals from amplifiers 86 and 90 are then used as previously described to hold the read/write head 14 over the desired data track.
  • Fig. 5 is a plot of the light intensity 110 across the width of the light reflecting portion 32 of one of the guidelines 20.
  • the light intensity 110 is highest at the very center of the light reflecting area 32 as shown at axis 112 of Fig. 5.
  • the light intensity 110 drops off as shown with the distance in either direction from the center of light reflecting area 32 as represented by "d" in Fig. 5.
  • the spot 54 upon which the optical system is focused is arranged to fall, when aligned properly, on desired points on the light intensity curve 110 such as the one-half intensity points 118 and 120. Thus, if the spot 54 is positioned in the exact center of 32 as shown in Fig.
  • each detector unit 80 and 82 will be equal to the shaded area under each half of the curve 110 from the center line 112 to the points 118 and 120 respectively. If the read/write head 14 drifts with relationship to the magnetic disk 10, and the spot 54 is no longer centered in area 32, the light received by each detector will no longer be equal. For instance, if the spot 54 wanders such that its center is displaced from the center of the area 32, the light received by the detector units 80 and 82 will no longer be equal. Thus, referring back to Fig.
  • a divided lightpipe 120 shown in Fig. 6 may be substi ⁇ tuted for the lightpipe 70 of Fig. 4 or the lightpipe 28 of Fig. 2.
  • the lightpipe 120 is divided, providing a first light conduit 122 and a separate second light conduit 124 over which light signals may be transmit- ted.
  • the lightpipe 120 is oriented in the read/write head 14 such that the servo motor moves the lightpipe 120 in the direction of the arrow 56.
  • Figs. 7-10 are other embodiments of the illumination and viewing portion of optical systems usable with the present invention.
  • a single lightpipe is used to both illuminate and view the surface of the disk 10.
  • a single lightpipe 130 is used which is a step index optical fiber which both conducts illumination light to the surface of the disk 10, and which returns light re ⁇ flected from the disk 10 to the optical sensors dis- cussed earlier.
  • a lens 132 is provided to focus the light on a spot 54 as discussed in connection with Fig. 3.
  • the lightpipe for conducting light reflected from the disk 10 to the sensors discussed in connection with Fig. 4 includes a step index optical fiber 140 whose end 142 is optically connected to a length of graded index fiber 144.
  • the graded index fiber 144 acts as a lens to focus the view of the lightpipe on a spot as previously discussed.
  • Fig. 9 illustrates a lightpipe which has a central core 150 made up of a graded index optical fiber, and which is clad by a layer of step index optical fiber 152.
  • An illuminating source 154 powered by an appropriate power source 156, is optically connected to the layer 152 for illuminating the layer 152, which in turn illuminates the surface of the disk 10.
  • the graded index fiber optic core 150 focuses the view of the lightpipe on a spot on the disk 10 as previously discussed.
  • Fig. 10 illustrates an overfilled aperture in which a beam of light is used to both illuminate the disk 10, and to view light reflected from the disk 10 carrying, the image of guidelines recorded thereon.
  • a read/write head 160 similar to the read/write head 14 shown in Fig. 1, has an aperture 162 axially there ⁇ through.
  • a light beam 164 is directed through the aperture to illuminate the disk 10, and a lens 166 is centered in the aperture 162 to focus the view of the light beam on a spot on the disk 10 as previously described.
  • a lens 166 is centered in the aperture 162 to focus the view of the light beam on a spot on the disk 10 as previously described.
  • a mirror such as the mirror 72 shown in Fig. 4 must be accurately aligned with the aper ⁇ ture to direct light reflected from the disk 10 to sensors as described in connection with Fig. 4.

Landscapes

  • Moving Of The Head To Find And Align With The Track (AREA)

Abstract

Appareil et procédé pour positionner de manière sélective une tête de lecture et d'écriture (14) près d'un milieu d'enregistrement (10) sur lequel des lignes de guidage optique (20) ont été enregistrées pour l'écriture ou la lecture magnétique de données sur l'une des nombreuses pistes de données. Chaque piste de données est associée à l'une des lignes de guidage optique (20) et peut comporter un code optique d'identification. L'appareil comporte une source de lumière (26) pour éclairer le milieu d'enregistrement (10) proche de la tête de lecture et d'écriture (14), ainsi qu'un système de détection de lumière (28) pour détecter la lumière réfléchie (46) par l'une des lignes de guidage optique (20). Un servo-mécanisme (60) ajuste la position de la tête de lecture et d'écriture (14) en réponse à la lumière réfléchie (46) détectée par le système de détection de lumière (28). Comme l'information de piste est enregistrée optiquement sur le milieu d'enregistrement (10), cela permet une détection optique, qui est plus précise et n'interfère pas avec la fonction de lecture et d'écriture magnétiques de la tête (14), le milieu étant capable de porter plus d'informations de données enregistrées magnétiquement que des milieux conventionnels de la même taille.
EP85900434A 1983-12-27 1984-12-19 Milieu d'enregistrement magnetique et appareil et procede pour suivre une piste de celui-ci Withdrawn EP0167570A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US56612483A 1983-12-27 1983-12-27
US566124 1983-12-27

Publications (1)

Publication Number Publication Date
EP0167570A1 true EP0167570A1 (fr) 1986-01-15

Family

ID=24261593

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85900434A Withdrawn EP0167570A1 (fr) 1983-12-27 1984-12-19 Milieu d'enregistrement magnetique et appareil et procede pour suivre une piste de celui-ci

Country Status (3)

Country Link
EP (1) EP0167570A1 (fr)
JP (1) JPS61500877A (fr)
WO (1) WO1985002933A1 (fr)

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Also Published As

Publication number Publication date
WO1985002933A1 (fr) 1985-07-04
JPS61500877A (ja) 1986-05-01

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