Abstract: A mold is for molding DVD discs to be joined together, back-to-back, to make a single disc. The mold includes a movable moldhalf and a stationary moldhalf. On one of the half-molds an inserting block extends a small distance into the mold cavity, so that the central part of the cavity is thinner than the outer part. The inner part and the outer part correspond approximately to the outer information band and the inner portion of the disc which is grasped. The mold is preferably used in a method using first a lower compression force during resin injection and then an increased force.

Abstract: A process of manufacturing the optical discs by injection molding includes compulsive forced cooling of the molded discs, carried out after sputtering to shorten the cooling time in the mold, in consideration of keeping the replication errors in the pits on the molded discs. The process also includes metallizing the surface of the molded discs by sputtering (to make laser beams reflect). UV resin coating for protecting the metallized surface of the discs, and inspecting the pits for replication of information signals quality.

Abstract: In a mold for molding data discs having a stationary cylindrical member and a movable cylindrical member fixed to a stationary moldhalf and movable moldhalf respectively, in each of which a stationary mirror plate and a movable mirror plate are fixed, an outer peripheral ring is set on the outer peripheral surface of the movable mirror plate, having a protrusion in the lower portion of a small inner peripheral surface of the outer peripheral ring for preventing leakage of air blowing into a cavity to release the discs from the stamper.

Abstract: A mold for molding digital data discs has interchangeable stampers. An outer peripheral stamper retainer and a mirror block with a convex portion allow interchange without dismounting the mold. The outer stamper peripheral retainer has a plurality of arcuate slots connected or disconnected to a plurality of rods provided with a stationary half-mold and to a corresponding plurality of holder bushings and a mirror block with a convex portion whose diameter fits an inner diameter of the outer stamper peripheral retainer. The outer stamper peripheral retainer and the mirror block correspond in size with a disc to be molded.

Abstract: A mold for molding disk substrata is capable of changing a set position of a stamper plate on a mold cavity. A pair of mirror plates are respectively for forming the surface of a disc cavity or for back stay of stamper plate. The set position of mounting the stamper plate is capable of being performed due to changing selectively the set position of the mirror plate. An inner stamper holder and stamper plate are held on the mirror plate by vacuum force to admit setting operations to ease.

Abstract: A central aperture of a molded disc being severed by protruding of the gate cutter and also a molded disc being released from a cavity by blowing of air from the passage provided between an inner periphery of the central stamper holder and an outer periphery of the bushing into the cavity, the molten resin with which the protruded gate cutter is surrounded, is pressed by the first protrusion of an ejector sleeve for preventing occurrence of a round corner D formed along the edge of the central aperture and for preventing generating of the clouds on the surface of the information area of the disc.

Abstract: A vacuum hot platen press for pressing laminated boards includes a seal cover assembly for keeping the internal process chamber airtight. The seal cover assembly is fixed in an airtight manner to a cylinder plate located below the platens, through which the pressure cylinders extend in an airtight manner. The upper end of the cover assembly is in sliding airtight contact with the tensile strength members of the press. The sliding contact prevents elongation of the tensile members under pressing force, or vacuum forces on the cover assembly, from causing distortion or breakage.

Abstract: An injection mold for disc molding such as in the manufacture of video or audio discs. The mold has a stamper removably clamped to one mold half by a rotating stamper holding ring. Both mold halves contain a plurality of clamping pins which selectively engage and hold slots in the holding ring. By rotating the holding ring, disengagement of the ring with the pins of the mold half carrying the stamper occurs simultaneously with engagement of the ring with the pins of the other mold half. Thereby, the stamper is released and may then be replaced.