Abstract: Method and apparatus for producing a mechanically reproducible recording in a metal disk record by operating an electrically excited cutting stylus to cut a modulated groove in the record, orienting the cutting stylus to be driven at a tracking angle of less than 5.degree., and electronically compensating recording distortions caused by this tracking angle.

Abstract: A device for removing a chip produced during cutting of information into a record carrier, particularly a metallic record carrier, wherein the cut chip is removed by means of suction air and the magnitude or pressure of this suction air is controlled in dependence on the depth recording component of the recording.

Abstract: A disc-shaped information carrier produced by thermoplastic deformation comprising a pressed mass including a co-polymer of vinyl chloride having additives incorporated therein. The carrier has hygroscopic properties and relief-like surface portions which are sufficiently yielding to permit pressure scanning.

Abstract: Process for manufacturing a record carrier having a cuttable copper layer, wherein a copper layer is precipitated onto a substrate in an electrochemical bath and a desired Vickers hardness in the precipitated copper layer is obtained by controlling the concentration of brightener additives. The copper layer is precipitated in a recrystallizable phase, and the recording is cut while the copper layer is in its recrystallizable phase.

Abstract: Apparatus for recording an information signal on a metallic record carrier. The information is impressed on the carrier by cutting a groove therein by means of a stylus, the groove being characterized at each point by a slope or modulation pitch angle. The stylus has a longitudinal axis, a leading edge substantially parallel to this axis and a trailing edge. The angle between the longitudinal axis of the stylus and a normal to the surface of the record carrier is greater than 10.degree. and not more than a value which would make the angle between the trailing edge of the stylus and the surface of the record carrier less than the maximum modulation pitch angle. The stylus is movably attached to a fixed structure by a mounting member and is electromagnetically excited by a driving member to shape the grooves in the record carrier in accordance with the information signal.

Abstract: In an apparatus for forming a groove which is modulated to present an information track in a signal record carrier having a copper surface portion by cutting such groove into the copper surface portion by means of a cutting stylus, the stylus is formed to present, during cutting, a rake angle of between 10.degree. and 20.degree., and the copper constituting the surface portion into which the groove is cut has a Vickers hardness of between 110 and 300, and preferably between 120-220.

Abstract: A method for producing a record copy disc by cutting a spiral groove into an original provided with a centering formation centered relative to the spiral groove, electrochemically transferring the groove pattern from the original to a master and forming the copy disc from the master, the step of transferring is performed so as to reproduce the centering formation electrochemically on the master, and the step of forming the copy disc is performed so as to form a centering formation on the copy disc from the reproduced centering formation on the master.

Abstract: A process for producing and operating an electroplating bath in which there appears NH.sub.4.sup.+ ions which impair the quality of the bath comprising adding salts of a hexanitrocobaltate-III complex to the bath to bring about precipitation of the NH.sub.4.sup.+ ions.