Metal mold device for molding a disc substrate

A metal mold device for molding a substrate comprising:

• a first metal mold,
• a second metal mold mounted facing said first metal mold, one of the first metal mold and the second metal mold being movable toward and away from the other of said first metal mold and said second metal mold, the second metal mold defining a mold cavity between it and said first metal mold,
• a stamper mounted on said first metal mold and arranged within said mold cavity,
• a sprue bushing having a resin injection port for guiding the molten resin therethrough, said sprue bushing being mounted on said first metal mold for facing said injection port within said mold cavity via a mid part of said first metal mold, said sprue bushing being engaged with the central aperture in said stamper for positioning said stamper,
• holding means for holding an outer rim of the stamper with respect to the first metal mold, and
• stamper attraction means mounted in the metal mold on which said sprue bushing is mounted for holding said stamper by attraction.

A metal mold device for molding a disc substrate having a bottomed centering aperture and a reference loading plane for disc rotating and driving means, said reference loading plane being substantially parallel to the planar region on which a reproducing light beam is incident, said reference loading plane being projected from said planar region, comprising

• a first metal mold,
• a second metal mold mounted facing said first metal mold, one of the first metal mold and the second metal mold being movable toward and away from the other of said first metal mold and said second metal mold, the second metal mold defining a mold cavity between it and said first metal mold,
• a stamper having a central aperture, mounted on said first metal mold, and arranged within said mold cavity,
• mounting means for mounting said stamper on said first metal mold,
• a first member mounted on the second metal mold for forming said bottomed centering hole,
• a second member arranged inwardly of said first member on the same axis as said first member, said second member being movable relative to the second metal mold for forming said through-hole, and
• a sprue bushing having a resin injection port for guiding the molten resin therethrough, said sprue bushing being mounted on said first metal mold for facing said injection port within said mold cavity via a mid part of said first metal mold, said sprue bushing being engaged with the central aperture in said stamper for positioning said stamper.