Molding die apparatus, method for molding disc substrate, and disc-shaped recording medium

A disc molding apparatus comprising:

• a stationary die, a movable die, including a molding surface and an outer circumferential ring for together molding a disc-shaped recording medium;
• the stationary die having a molding surface for forming the surface of the disc opposite the moveable die;
• and
• the outer circumference ring being for molding the outer circumference of the disc;
• the outer circumference ring being movable along forward and backward directions in parallel with a direction of movement of the movable die relative to the stationary die;
• characterized in that the outer circumference ring has a retaining surface, when a disc is molded, parallel to the said molding surface of the movable die for forming an outer circumferential surface of the disc parallel to and at the same level as the said molding surface, which outer circumference surface is a continuous or discontinuous ring and an edge surface extending at a single angle transversely from the retaining surface to the surface of stationary die to form the transverse edge of the molded disc from the retaining surface to the surface of the stationary die.