Abstract: It is possible to obtain a disk substrate in which an edge of a center hole is free of flash. The disk substrate (23) in which the center hole (24) is provided with a straight portion (24a) and a tapered portion (24b), and an edge on the side of a signal transfer surface (22) of the tapered portion (24b) is provided with an R surface or C surface (24c), a mold apparatus optimum for molding the disk substrate (23), and a disk taking-out apparatus.

Abstract: A method of producing an information recording medium having enhanced planarity with high productivity, comprising steps of processing a surface of a disk substrate by satin-like finishing, heating and pressing the disk substrate through compression using a stamper having relief shapes so as to transfer the relief shapes to at least one satin-like finished surface of the disk substrate, forming a recording layer on the relief shape surface of the disk substrate, and forming a coating layer on the recording layer, and a production apparatus for the information recording medium, and an information recording medium produced by the method of producing.

Abstract: It is possible to obtain a disk substrate in which an edge of a center hole is free of flash. The disk substrate (23) in which the center hole (24) is provided with a straight portion (24a) and a tapered portion (24b), and an edge on the side of a signal transfer surface (22) of the tapered portion (24b) is provided with an R surface or C surface (24c), a mold apparatus optimum for molding the disk substrate (23), and a disk taking-out apparatus.

Abstract: A recording medium for information signals including a substrate, a signal recording layer provided on one major surface of the substrate and a clamp member having a positioning unit at its center portion and formed of a material that can be magnetically attracted by a magnet. The clamp member is unified to the center portion of the substrate so that the surface of the clamp member will be flush with the substrate surface.

Abstract: It is possible to obtain a disk substrate in which an edge of a center hole is free of flash. The disk substrate (23) in which the center hole (24) is provided with a straight portion (24a) and a tapered portion (24b), and an edge on the side of a signal transfer surface (22) of the tapered portion (24b) is provided with an R surface or C surface (24c), a mold apparatus optimum for molding the disk substrate (23), and a disk taking-out apparatus.

Abstract: A method of producing an information recording medium having enhanced planarity with high productivity, comprising steps of processing a surface of a disk substrate by satin-like finishing, heating and pressing the disk substrate through compression using a stamper having relief shapes so as to transfer the relief shapes to at least one satin-like finished surface of the disk substrate, forming a recording layer on the relief shape surface of the disk substrate, and forming a coating layer on the recording layer, and a production apparatus for the information recording medium, and an information recording medium produced by the method of producing.

Abstract: A recording medium for information signals including a substrate, a signal recording layer provided on one major surface of the substrate and a clamp member having a positioning unit at its center portion and formed of a material that can be magnetically attracted by a magnet. The clamp member is unified to the center portion of the substrate so that the surface of the clamp member will be flush with the substrate surface.

Abstract: An optical disc molding apparatus is able to mold an optical disc in which the occurrence of swollen portions of trumpet shape on the upper and lower surfaces of on the outer peripheral portion of a disc base may be minimized and in which a burr may be prevented from being produced on the outer peripheral portion of the disc base. In the optical disc molding apparatus having a ring (6) for molding an outer diameter portion of a disc base and holding a stamper (5) for transfer a signal pit, a holding surface of the ring (6) for holding the stamper (5) is formed as the concave and convex surfaces comprising a plurality of concentric land portions (21) and a plurality of concentric groove portions (22). The outer peripheral surface of the stamper (5) is held by each land portion (21) with a pressure.

Abstract: An optical disc molding apparatus is able to mold an optical disc in which the occurrence of swollen portions of trumpet shape on the upper and lower surfaces of on the outer peripheral portion of a disc base may be minimized and in which a burr may be prevented from being produced on the outer peripheral portion of the disc base. In the optical disc molding apparatus having a ring (6) for molding an outer diameter portion of a disc base and holding a stamper (5) for transfer a signal pit, a holding surface of the ring (6) for holding the stamper (5) is formed as the concave and convex surfaces comprising a plurality of concentric land portions (21) and a plurality of concentric groove portions (22). The outer peripheral surface of the stamper (5) is held by each land portion (21) with a pressure.