Playback instrument for an information carrier disc

Claim 1

In a playback instrument for a record disc provided with a center region and with recorded information located exclusively in a second region enclosing the center region, the instrument including a turntable for supporting the disc to be played, on which the disc is centered by means of a central bore, the improvement comprising means defining two annular, concentrically disposed, radially spaced flat bearing surfaces mounted on said turntable for the disc with the portion of said turntable between said surfaces being recessed below said surfaces, said surfaces forming a rigid support, one said bearing surface being disposed in the vicinity of the location of the center of such disc and the other said bearing surface being disposed radially to the outside of said one surface at a distance from the location of the center of such disc to contact the radial outer portion of the center region of the disc, and disc holding means provided for exerting on such disc a magnetic attracting force of such magnitude as to cause the disc to contact said bearing surfaces over the entire area thereof, and wherein said turntable comprises a disc centering pin having a conical surface dimensioned for engaging the central bore of the disc and said one bearing surface is spaced radially from said pin, said conical surface protruding beyond said bearing surfaces to such an extent as to cause a record disc placed on said turntable to be slightly curved, when the disc is in contact with said bearing surfaces, in the region of the disc which is radially enclosed by said one bearing surface to produce a spring force in the disc which acts to center the disc on said centering pin.