DE2506426A1 - RECORDING DEVICE FOR STORING AND REPLAYING DATA - Google Patents

Description

PfIN. 7310 22-1-1975

/: - PHM- ^ 310

a ■ ^ Zt TPja'h-r

fi-svorrlcJitixng for Sfjoiolierung · and playback of data ".

The invention relates to a AufzelcTri-

nung.svorri.clj.tung "with a magnetizable data carrier cooperating magnetic ¥ and.lerelemeat.

To f; eiclimmg-ßvorricli tung · of this type are iiiagiiotisc liue Scbol lioaspoicher ( "flowing ^ netic di.ic files ¹ '.) Can be used in doncn langnotischo glass panes in the Rtn 3ch: O'i: i bo3i and data readout magne tisolie Vandlerol (iiüentc (magnetic head ei) work together,

To design a magnetic disk with a very high Datondä r-lite, int a ¥ and3, erelenient necessary not only for there ;? Au.-slf very sclMulyr data-

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PHN. 7310 22-1-1975

tracks, but also for reading very close together lying tracks is suitable. The latter means that the other element is read out with the help of a servo system must be kept centered on the middle of the read track, which is large when using conventional magnetic heads Problems.

The invention aims to provide a simple solution to these problems. The recording device according to the invention is characterized in that the lfandlerelement by a plate made of magnetizable em Material with a · preferred magnetization right perpendicular to the plane of the platelet containing a single-walled magnetic domain while on the platelet a detector for detecting changes in the field pattern of the data carrier brought about! "Changes in the size of the Domain and means are attached, with the help of which the position of the domain in the platelet can be corrected.

A single-walled magnetic domain, which is located in a Doiiiänenplattc, which with respect to the magnotized Disk is moved, is caused by the magnetic field the surface of the wearer influences: the size or location a single-walled magnetic domain depends on the field that thaws the domain, and is therefore affected by the field pattern of the data carrier; -; modulated.

Since magnetic domains are very Hein.31. (•;.!>. Can expand a cross section of 1 λιπϊ), it is

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possible., data carrier with a "large data diclite." read out.

The particular aspect of the recording device according to the invention now resides in; the possibility of that through the regulated movement of the domain in the domain plate a simple but very precise fine control of the position of the readout element with respect to the track to be read out can be obtained. The movement of the domain can have an angle the relative direction of movement of the data carrier, to center the domain on the track; it's too much possible to move the domain in the relative direction of movement of the data carrier, do with changes in speed Getting corrected.

A disadvantage of using magnetizable

Data carriers in ΑνΓ ζ e: i chnuiigs vor directions is that it is difficult to transfer the data they contain directly (by contact taping) to another data carrier, but data carriers in the form of disks are also known where the data (eg a video program) in the form of blocks b>: w. There are dimples of variable length in a spiral or concentric circle track (so-called "Yideolangspielplatte": see Dutch patent application 7-102.863). The application of this data - with the help of photolithographic techniques - is relatively simple, while such a carrier is used because of its relief structure

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suitable as a die from which copies can be made by means of a pressing process. Reading out the data such a carrier that takes place optically must, however, gives rise to certain problems. So it becomes a relatively intricate one for the exact focus required optical system, while with a spiral data track to obtain the desired slope at Following this track an extremely high level of accuracy is required (see e.g. the Dutch patent application 7.IO3.234). .

The present invention further aims to provide a recording device with a data carrier which can be read out using simple means as well as copied in a simple manner. For this purpose, the recording device contains a data carrier, in the surface of which there are mechanical deformations which are representative of the stored data, ¹ while the carrier consists of a layer of a magnetizable material or is provided with such a layer, which material is in one to the surface is permanently magnetized in the perpendicular direction.

Due to the presence of level differences (blocks or pits) in the surface of the carrier on the surface of the magnetized in the manner described above Data carrier has a magnetic field pattern that corresponds to the stored data. The magnetic field that a

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The transducer element scans when it is moved across the carrier, now changes depending on in the surface applied level differences. The advantage is that (magnetic) Copies can be made, e.g. by making impressions in magnetizable material by means of a pressing process are made from a motherboard and a magnetic field is applied to the copies obtained during pressing. One Another possibility is to make impressions in non-magnetizable material, these with a coating magnetisable material to be provided and this coating eventually to magnetize. The copies made in this way can be converted with the aid of the transducer element described above, which can follow the data track very precisely, can be read out. (An additional benefit is that that the optically attached data can still be read out optically).

Preferably the detector consists of two

parallel "detection elements made of magnetoresistive material, which are made on the plate on both sides of a groove that forms an angle with the direction of movement of the plate with respect to the carrier, the magnetic Domain is movable along the groove, while the magnetic domain in the plate made of magnetizable material as Function of an error signal obtained from a comparison of the Signals of the two detection elements is derived, moving

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bear is.

The invention is explained in more detail below, for example with reference to the drawing. Show it:

Fig. 1 shows a recording apparatus having a Data carrier and a transducer element according to the invention, and

FIG. 2 is a plan view of the transducer element according to FIG.

A plate made of magnetizable material 1, in which a single-walled magnetic domain 2 (so-called "bubble") is generated (FIG. 1), is brought into contact with a disk k with a data-carrying magnetic field pattern or is brought into contact with this disk at a small distance, in such a way that the illustrated X-direction is directed towards the center point of the disk h. A preload field H (in the + X direction) with a field strength sufficient to maintain the "bubble" 2 in the plate 1, which can be generated in a manner known per se, stands vertically on the plate 1. The disk h is provided with a data track 9 in the form of a spiral or made up of concentric circles. This track can be obtained, for example, by applying a photoresist to a disk made of magnetizable material, which is exposed intermittently during variable periods corresponding to the data by rotating the disk with respect to a point light source, in particular a laser. Thereafter, after developing the photoresist and applying a photo-etching process, one becomes off

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mechanical deformations existing track preserved. By doing the disk then evenly in a direction perpendicular to the surface! is magnetized, the in Fig,

1, in which a relatively strong field is present in the pane at certain points (8.8 ") and a relatively weak field at the other points (8 ·). These fields, together with the bias field H, determine the size of the "Bubble" 2 at a certain point above the disk surface. The size of the "bubble" 2 is modulated when the disk h is rotated 5 '(FIG. Z) gives an indication of the size of the "bubble" and thus of the data currently located in the track 9 under the "bubble" 2. When the "bubble"

2 exactly follows the track 9, the signal of the detector 5 is the same as that of the detector 5 '. If the "bubble" 2 deviates from such a track, there is a difference between the signals of the detectors 5 and 5'. The "Bubble'i plate 1 is now set up in such a way that the" Bubble "2 is fixed to a groove 6 in the plate surface, is determined by the ratio of the currents X ₁ and i" through the conductors 3 and 3 '"Bubble" ^ will be fixed at the point at which there is a minimal field between the conductors 3 and 3 '. The extent to which the "Bubble" 2 is fixed at a particular point in the groove 6 is determined by

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determines the absolute values of the currents X ₁ and i_. These values are set in such a way that the position of the "bubble" can easily be readjusted. This takes place in that the ratio of the currents X ₁ and i_ is changed until the difference signal of the detectors 5 and 5 'is again equal to zero. In this way, precise tracking of the track to be detected is obtained. For this purpose, the groove 6 is so long that it takes up some tracks. The track is roughly followed by regulating the movement of the arm 7 to which the plate 1 is attached.

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Claims (1)

PUN. 7310 23-1-1975 PATENT CLAIMS ; 1.) Recording device with one with one magnetizable data carrier cooperating magnetic transducer element, characterized in that the transducer element by a plate made of a magnetizable material with a preferred direction of magnetization perpendicular to the plane of the platelet containing a single-walled magnetic domain while on the platelet a detector for detecting changes in size brought about by changes in the field pattern of the data carrier the magnetic domain and means are attached, with the help of which the position of the domain is corrected in the platelet can be. 2. Device according to claim 1, characterized net that the domain in the platelet is movable along a straight line which forms an angle with the relative direction of movement of the data carrier with respect to the disc includes to the disc during playback on the Keep track centered. 3. Device according to claim 1, characterized in that the domain in the small plate can be moved along a straight line which coincides with the relative direction of movement of the data carrier with respect to the small plate in order to correct changes in speed during playback.
H. Device according to claim 2 or 3 »characterized by 509836/06 77 PHN. 7310 23-1-1975 indicates that the domain is along a groove in the surface of the plate is movable under the action of the adjustment of the currents through two conductors, which are each at one end of the groove parallel to each other and at an angle to the axis of the groove. 5. The device according to claim h, characterized in that along the long sides of the groove and at equal intervals between these sides, two detection elements parallel to one another are mounted on the plate, which together form the detector. 6. Apparatus according to claim 5 »characterized in that that the detection elements are made of magnetoresistive material. 7. The device according to claim 5, characterized in that the setting of the currents through the conductors is derived from a circuit which ^{compares the signals 5 of} the two detection elements with one another. 8. The device according to claim 1 ·, characterized by a data carrier, in the surface of which mechanical Deformations representative of the stored data are applied, while the data carrier consists of a: Layer consists of a magnetizable material or is provided with such a layer, which material in is permanently magnetized in a direction perpendicular to the surface. 509836/0677