Abstract: Disk-shaped magnetic recording media essentially consisting of a flexible substrate, a thin ferromagnetic metal film applied to one or both sides and a protective or antifriction layer present on this metal film and essentially consisting of carbon, a process for the production of these recording media and information stores containing these recording media.

Abstract: A method and an arrangement for reducing wear in magnetic storage means having magnetic disks, in particular having flexible media, become effective when predetermined maximum waiting times of the heads on the same track or the same tracks have elapsed. The heads HD are moved away from the waiting tracks in accordance with the predetermined control scheme, may be moved in waiting areas of the magnetic surface, and are moved back to the waiting position.

Abstract: Magnetic recording media consist of a flexible disk-shaped nonmagnetic base, a cobalt/chromium layer applied thereto and suitable for vertical recording, and a friction-reducing layer of amorphous carbon present on this alloy layer.

Abstract: In a protective jacket for disk-shaped recording media, for example magnetic films, fixed magnetic disks, grammophone disks or video disks, the fleece covering in the jacket is fastened close to the outer edges of the jacket and close to the contour lines of the openings by means of heat welded points a short distance apart and in the region inbetween at a distance apart which is several times as large. As a result of the cushions thus formed, a more advantageous cleaning effect is achieved.

Abstract: A positioning device, comprising a cylindrical guide element and a guide surface, is so designed that an angle of less than 90.degree., especially of from 1.degree. to 80.degree., is formed between an axis at right angles to the direction of movement of the guide element over the guide surface and the axis of rotation of the guide element, in the plane containing these two axes. The peripheral surface of the guide element can be grooved or convex. The novel positioning device can be used with advantage in any type of recording/playback apparatus for disk records.

Abstract: A method and an arrangement for detecting error signals in a magnetic disk drive apparatus uses a test disk which has a plurality of test tracks distributed over the recording area and containing special test signals, a distinction being made between orientation, adjustment and azimuth bursts. Based on the normal position of the recording tracks of the magnetic disk, the spacing of the test tracks could depend on the type of step motor if such a motor is used in the positioning device. By special control, hysteresis errors can be measured in addition to tracking errors, eccentricity errors and azimuth errors.An advantageous use is for all types of disk drives, preferably FlexyDisk drives.

Abstract: A process for the preparation of a magnetic recording medium by dispersing pulverulent magnetic material in a binder mixture which is dissolved in an organic solvent and essentially consists of an elastomeric polyurethane and a high molecular weight hydroxyl-containing polymer, with addition of dispersing assistants and conventional additives, applying a layer of the dispersion, to which a diisocyanate and/or polyisocyanate has first been added, to a base material and the solidifying the layer and crosslinking the binder matrix, wherein the diisocyanate and/or polyisocyanate is added to the dispersion and, before applying the dispersion to the base, from 15 to 55% of the NCO groups present react with the hydroxyl-containing polymer of the binder mixture.

Abstract: Magnetic recording media possessing a thin magnetic layer are produced by dispersing finely divided magnetically anisotropic material and conventional additives in a solution of a polymeric binder in an organic solvent, applying a layer of the dispersion to a non-magnetizable base by means of a knife-coater, then, if required, orienting the magnetically anisotropic material by means of a magnetic field and drying the applied layer, a high molecular weight organic compound which acts as a thickener being added to the magnetic dispersion.

Abstract: Magnetic recording media which have a thin backing coating and consist of a non-magnetic flexible base and a magnetic layer which is applied to one side of the base and comprises magnetic material finely dispersed in an organic binder are produced by applying a dispersion of finely divided non-magnetizable conductive and non-conductive solids and conventional additives in a solution of a polymeric binder in an organic solvent to that side of the base which is opposite the magnetic layer by means of a knife-coater, and then drying the layer, a high molecular weight organic compound which acts as a thickener being added to the backing coating dispersion.

Abstract: A method and apparatus for burnishing the surface of magnetic recording media, wherein there is relative movement between the surface to be burnished and the abrasive member, and the abrasive member is urged against the said surface, the pressure applied being increased over a period of time or at a plurality of locations, and then being reduced again.

Abstract: A process for authenticating recording media which are to be safeguarded against falsification and which possess a layer of exchange-anisotropic magnetic material, by determining the residual recording which is left over, because of the exchange anisotropy of the magnetic material, from a recording of a sequence of signals after exposure of the material to a specific temperature cycle and, subsequently, to a magnetic AC field which decreases to zero, and an apparatus for carrying out the said process.

Abstract: A drive apparatus for a recording disk, particularly a flexible magnetic disk in an envelope, comprising a rotatable clamping member which can be caused to engage one another, after the recording disk has been introduced therebetween, to clamp the disk for rotation thereof, in position between clamping surfaces of the two members. The clamping member is of axially expandable design and a resilient element is interposed between the face of the clamping member and the bottom of the recessed member so that the clamping member, prior to completion of its stroke and prior to its radial expansion, is engaged by the spring element. In this manner the spring element centers the position of the clamping member with respect to the recessed member and thereby insures clamping of the disk in its centered position.

Abstract: A process for authenticating recording media which are to be safeguarded against falsification and which possess discrete regions of an exchange-anisotropic magnetic material, by comparison of the polarity of a residual magnetization which is left over, because of the exchange anisotropy of the magnetic material, from a predetermined initial magnetization after exposure of the material to a specific temperature cycle and, subsequently, to a magnetic AC field which decreases to zero, with the polarity of a residual magnetization formed in the same way from an opposite initial magnetization, and an apparatus for carrying out the said process.

Abstract: A magnetic head positioning servo arrangement for a system for recording or reproducing information on a flexible magnetic recording medium, the position of the head being adjustable, relative to the magnetic tracks of the recording medium, by means of an actuator, and each magnetic track being provided with at least one reference signal which, when sensed, provides information about the momentary position of the head and, in the case of mistracking, generates in a comparator circuit a control signal for the actuator which moves the magnetic head back over the center of the track, the reference signal consisting of at least one pair of pulse sequences which are recorded asymmetrically with respect to the center of the track and which, when sensed, produce increasing or decreasing signal pulses.

Abstract: A magnetic recording medium comprising a non-magnetic base and a magnetizable layer which is applied to at least one side thereof and comprises magnetic particles finely dispersed in a polymeric binder and additives, the surface of the magnetizable layer being provided with a coating of a perfluoropolyether oil mixture as a lubricant.

Abstract: Magnetic recording media comprising a non-magnetic base and, applied thereto, a firmly adhering magnetic coating based on a finely divided magnetic pigment dispersed in a binder which contains at least 50 percent by weight of a special polyurethane elastomer, namely a thermoplastic polyurethane which is soluble in tetrahydrofuran, is free from isocyanate groups and has been manufactured from (A) 1 mole of a hydroxyl-containing polyester having a molecular weight of from 700 to 2,500, (B) from 0.3 to 3 moles of a linear aliphatic diol of 2 to 10 carbon atoms, (C) from 0.05 to 0.4 mole of a triol of 3 to 10 carbon atoms, and (D) from 1.35 to 4.7 moles of a diisocyanate of 6 to 30 carbon atoms, the amount of NCO groups being approximately equivalent to the amount of OH groups of the sum of components (A) to (C).

Abstract: A device for compensating for an inequality between the d.c. magnetic fields set up by the two oppositely acting windings, respectively, of the magnetic heads of a data storage device, particularly a disc memory, and a data storage apparatus including such a device, the device comprising means for generating a compensating direct current and feeding this current at the appropriate time to a predetermined one of the two windings of the magnetic heads. The magnitude of the compensating direct current is advantageously adjusted in dependence on the instantaneous magnitude of the write current.

Abstract: The invention concerns a system for recording and/or reproducing data signals on a magnetic recording medium, more particularly a new improved transducer locating system. The magnetic transducer is provided with an air gap for the data track and a second air gap for the reference track which latter is formed on a recording medium as a transition line between regions of varying magnetization and arranged within, or laterally of, the data track. As the transducer deviates from its desired track position, a correction signal is produced which is fed to a locating device to which the transducer is fitted, in order to adjust the position of the transducer.

Abstract: The invention relates to a magnetic disc for track adjustment and amplitude control having at least one control track with magnetic control signals, this track being arranged in the central region of the recording area, and the control signals consisting of two different signals. The invention also relates to the geometric arrangement of the control signals in the track, their number, their amplitude, their frequency and their duration.

Abstract: Magnetic recording media comprising a base and, applied thereto, at least one firmly adhering magnetic layer based on magnetic particles dispersed in a mixture of organic binders, wherein at least the uppermost magnetic layer additionally contains non-magnetic particles of precipitated silica having a primary particle diameter of from 0.02 to 0.1.mu., a secondary particle diameter of from 2 to 4.mu. and a pH of from 5 to 8.As a result of the incorporation of such a precipitated silica into the magnetic layer, the coefficient of friction between the latter and metals remains uniformly low even after prolonged use, and no stick-slip motion occurs.