Forming prerecorded optical disc substrate in high speed moulding process

摘要

A substrate for an optical disc, especially compact discs or CDs, the pre-recorded, moulded substrate is formed from a molten resin using a die carrying projections. These have predetermined shape and unusually, are sized excessively, in comparison to the pits to be formed in the substrate. Preferably, the moulded substrate satisfies the standards for optical discs or plates. The projections have height H; the pits have depth d. The ratio H/d is 1.3 to 1.8. The moulding tool temperature is 40-70 deg C and the resin is cooled for 1.5-2.5 s.