Abstract: There is provided an intermediate for an optical recording medium, which can be uniformly coated with resin by the spin coating method without using a resin coating-assisting member, and allows formation of a central mounting hole without burrs. The intermediate comprises a hollow cylindrical protruding portion protruding from one surface on which functional layers are formed and a circular recess formed in a central portion of the other surface and having a diameter equal to that of the central mounting hole, and a temporary central hole formed to extend through a central portion of the recess and having a diameter smaller than that of the recess. The protruding portion has an outer diameter smaller than the diameter of the mounting hole and an inner diameter not smaller than the diameter of the temporary central hole, and has a central axis thereof substantially aligned with a center of the temporary central hole.

Abstract: There is provided a mold component which makes it possible to mold a substrate for an optical recording medium which enables a functional layer having a uniform thickness to be formed thereon without using a resin-coating assisting member. A stamper holder holds a stamper thereon, and has a generally hollow cylindrical shape. An insertion hole formed through a central portion of the stamper has a diameter which is larger than an outer diameter of a cavity-side end of the stamper holder at a higher temperature of the holder than a normal temperature, and is slightly smaller than the outer diameter at the normal temperature of the holder. The cavity-side end inserted into the insertion hole at the higher temperature of the stamper is grasped by a rim of the insertion hole which is reduced in diameter at the normal temperature of the stamper.

Abstract: A disc-shaped substrate for a disc-shaped optical recording medium is accurately and stably positioned and held during a sputtering process. A non-sputtering surface of the disc-shaped substrate opposite to a sputtering surface has a circular recess formed at a center thereof. A carrier, on which the disc-shaped substrate is supported during the sputtering process, has a projective member for fitting into the circular recess to accurately position and hold the disc-shaped substrate during the sputtering process.

Abstract: A method for manufacturing a disc-shaped optical recording medium is provided, according to which a disc-shaped substrate with no central hole is accurately and stable positioned, when the substrate is spin-coated. A circular recess is formed in the center of a non-coated surface opposite to the surface to be coated of the disc-shaped substrate in the spin-coating step, and a ring-shaped raised rim to fit with the circular recess is provided on the side of a substrate holding portion supporting the disc-shaped substrate during spin-coating. The ring-shaped raised rim is fitted with the circular recess, so that the disc-shaped substrate is accurately positioned and held during the spin-coating step.

Abstract: A method for manufacturing a disc-shaped substrate material for an optical disc with a center hole is provided so as to form a resin layer with a uniform thickness distribution in a simple process. A stamper 10 is held to a movable metal mold 34 by suction means 36 in a cavity 31 in a mold assembly 30. The stamper 10 includes a through hole 10A with a diameter smaller than that of a center hole of an optical disc. When a disc-shaped substrate material 12 formed by injection molding is solidified, and the movable metal mold 34 is separated from a fixed metal mold 32, release means 38 is protruded from the through hole 10A so as to push the disc-shaped substrate material 12 for release.

Abstract: An optical recording disk includes on a substrate 2, a dye recording layer 3, a lower reflective lamina 4, an upper reflective lamina 5, and a protective coat 6. The lower reflective lamina 4 is formed of Au, Pt, Ag, Al or an alloy thereof and the upper reflective lamina 5 is of a stainless steel composition or an alloy containing 30 wt % or more of Cu and at least one element selected from the group consisting of Zn, Ti, V, Ta, Cr, Mo, W, Mn, Fe, Co, Rh, Ni, Pd, Pt, Ag, Au, Al, Sn, Si, Pb, Cd, Hg, Ca, In, As, Sb, Bi, Se, Te, Ge, N and O. The disk is well reliable and less costly.

Abstract: In an optical recording medium comprising a recording layer on a substrate, a reflective layer in the form of a Cu-Ag or Cu-Au alloy thin film is formed on the recording layer. The Cu-Ag alloy contains 5-40 atom% of Ag and the Cu-Au alloy contains 5-99 atom% of Au. The reflective layer has enough high reflectivity, corrosion resistance, and hardness to provide optical recording medium with improved eye pattern, minimized jitter and minimized error rate.

Abstract: In preparing an optical recording disk by spin coating a dye-containing solution to an annular substrate to form a recording layer thereon, a circular channel is preformed in the substrate in proximity to the inner peripheral edge of the substrate for defining an inner boundary of the recording layer. Then the recording layer is free of corrugations near its inner boundary, leading to improved adhesion of an overlying protective film and a minimal variation in reflectivity.

Abstract: A method for manufacturing a tape guide cylinder of small thickness from metal sheet by combination of drawing processing technique, flange processing technique, piercing technique, trimming technique, curling technique and optionally burring technique of metal working processing is disclosed. The tape guide cylinder produced has flange-like inward portions or inwardly bent portions at both ends of the cylinder which fit on cylinder attaching shaft of a cassette case, respectively. Therefore, the inward portions or inwardly bent portions contribute the reduction of the thickness of the cylinder body and thus the reduction of the material used for the production of a tape guide cylinder.

Abstract: A process for preparing a tape guide cylinder is disclosed, which includes the steps of deep-drawing a sheet metal material progressively to form an elongated cylinder with a bottom, subjecting the resulting cylinder to flange-machining to form a flange at its open end, thereafter removing the bottom of the cylinder, subsequently trimming the flange from the cylinder, and finally subjecting the resulting cylinder at either of its ends to a beat-machining for finishing the shape of the elongated cylinder.The tape guide cylinder thus prepared may further be subjected at its circumference, to a precision finish for providing an outer diameter of less than 6 mm but more than 5.2 mm.

Abstract: An optical recording disk wherein information is written and reproduced through the application of recording and reading laser beams is assembled by preparing a pair of circular substrates which each are provided with a plurality of studs or spikes on outer and/or inner circumferential band, forming a recording layer of dye on each substrate, and joining the substrates together through the studs by ultrasonic sealing or adhesive bonding such that the recording layers face one another via an interior space.