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: A device for centering a record disc with respect to a turntable, in which the disc is successively radially centered and axially positioned relative to the turntable, which device includes a centering shaft engageable with the disc to effect preliminary radial centering thereof, is additionally provided with further radial centering elements mounted to engage a disc after it has engaged the shaft and to undergo yieldable movement relative to the turntable in the axial direction of the disc under the influence of its engagement with the disc for effecting final radial centering of the disc, and a magnetic attracting unit operatively associated with the disc and the turntable for axially positioning the disc after it has been finally radially centered.

Abstract: A playback instrument for a record disc, the instrument including a turntable for supporting the disc to be played on which the disc is centered by means of a central bore, is provided with two annular, concentrically disposed, radially spaced flat bearing surfaces mounted on the turntable for the disc, the surfaces forming a rigid support, one bearing surface being disposed in the vicinity of the location of the center of such disc and the other bearing surface being disposed radially to the outside of the one surface at a distance from the location of the center of such disc, and disc holding components provided for exerting on such disc an attracting force of such magnitude as to cause the disc to contact the bearing surfaces over the entire area thereof.

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 rigid polyvinyl chloride foil with modified impact resistance and free from plasticizer especially suitable for the manufacture of audio-visual information carriers with stamped spiral grooves from which the information is played back by pressure scanning. The foil is characterized by a special combination of properties such as flow, reduction in length, toughness, surface resistance, elasticity, peak-to-valley height and surface deposit.

Abstract: In the production of disc recordings, the label portion therefor is formed by tracing a pattern of essentially circular grooves or arrays of dots and groove or dot-free areas in the location of the label portion, the grooved areas contrasting visually with the groove-free areas and the pattern being such that one type of area, preferably the groove-free areas, forms the legible characters and patterns to appear in the label portion.

Abstract: A grinding foil which is to be used for grinding a record cutting or playback stylus is manufactured by providing a surface layer of a plastic foil with indentations for accommodating a grinding agent in granular form, filling the indentations with such grinding agent, and thermoplastically deforming the surface layer to smooth the foil surface and to bond the grinding agent into the surface layer.