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 head arm mounting device for one or more scanning heads in recording/playback apparatus for disk records, especially flexible magnetic disks, includes a pivot shaft for the head arm, this shaft being held in a mount, with the aid of spring means, in a manner such that it has no axial play, and producing, in conjunction with the head arm loading spring, a head loading force which is constant and essentially independent of the head arm deflection. The mounting device consists essentially of a mount and a pivot shaft, either of which may be associated with a spring. A one-piece frame-shaped member with an integral spring constitutes an optimum mount. In an advantageous embodiment, means are provided for finely adjusting the force exerted by the head arm loading spring, and for compensating for tolerances in the spring force of the loading spring in the quantity production of disk drive apparatus.

Abstract: A carriage for a scanning head in recording and/or playback apparatus for disk records, a first rod-shaped guide member being provided for the support and longitudinal guidance of the carriage, and a second rod-shaped guide member being provided for the transverse support of the carriage, wherein the carriage possesses at least one prism-shaped aperture for said first rod-shaped guide member, and at least one leaf spring presses the carriage against the rod-shaped guide members.

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: In a method of electrodepositing a palladium/nickel alloy coating upon a substrate wherein the coating is plated onto the substrate by electrodeposition from a bath containing 5 to 30 g per liter of palladium and 5 to 30 g per liter of nickel and having a palladium-nickel ratio such that the coating contains 30 to 90% by weight of palladium, the improvement which comprises providing in the bath during the eletrodeposition of the coating at least one sulfonyl urea compound capable of improving the corrision resistance of the coating.

Abstract: A method of electrodepositing a palladium/nickel alloy coating upon a substrate wherein the coating is plated onto the substrate by electrodeposition from a bath containing 5 to 30 g per liter of palladium and 5 to 30 g per liter of nickel and having a palladium-nickel ratio such that the coating contains 30 to 90% by weight of palladium. The bath is provided during the electrodeposition of the coating with at least one acetylene amine or amino alcohol capable of improving the brightness and mechanical properties of the coating.

Abstract: In a method of electrodepositing a palladium/nickel alloy coating upon a substrate wherein said coating is plated onto said substrate by electrodeposition from a bath containing 5 to 30 g per liter of palladium and 5 to 30 g per liter of nickel and having a palladium-nickel ratio such that the coating contains 30 to 90% by weight of palladium, the improvement which comprises providing in said bath during the electrodeposition of said coating at least one acetylene alcohol or acetylene alcohol ether capable of improving the brightness and mechanical properties of said coating.

Abstract: A pressure device for flexible recording media, especially those contained in cartridges, which comprises a rigid member provided with a resilient pad, which member, secured to a pivoted lever, is located in front of the write/read area of the scanning head relative to the direction of rotation of the recording medium, and presses the recording medium against a platen, wherein the rigid member is connected to the pivoted lever via a universal joint.

Abstract: Positioner for the scanning head, mounted on a carriage, in a recording and/or playback apparatus for disk records, with a cable extending between the carriage and the drive motor, and a spring as counterforce, which positioner comprises a pulley, mounted on the carriage, and two pulleys of different diameter which are mounted on the shaft of the drive motor and to which the beginning and end of the cable are fixed, the pulley system operating on the differential pulley principle, so that greater accuracy of positioning is achieved and less torque has to be produced by the motor.

Abstract: A device, provided on a recording/reproducing apparatus, for adjusting and fixing a detecting means relative to the index mark on a recording disc, which device comprises a holding device for the detecting means, the position of which can be altered and which can be aligned and fixed relative to the index mark, the holding device consisting of a slidably mounted member made of a suitable material and having at least one elongated hole, and of a spring which exerts a biassing force on the slidably mounted member which moves on an arcuate path.

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: A process for the chemical coating of synthetic-resin bodies with nickel or copper utilizing an activation step in which the bath comprises:0.1 to 20 g gelatin or gum arabic as the protective colloid, 1 to 5 g tartaric acid or citric acid, 1 to 5 g sulfuric acid or hydrochloric acid, 0.1 to 5 g palladium sulfate, 1 to 20 g maleic acid or 1 to 6 g fumaric acid as poly basic carboxylic acids, and water to a volume of 1 liter. The subsequent treatment with the chemical plating bath is carried out without an intervening acceleration treatment.