Patent ID: 7052269

Claim:
A die assembly, for molding optical disc substrates, that comprises an outer circumferential stamper holder having: a stamper holding portion that holds an outer circumferential edge portion of a stamper disposed on a specular plate; and an inner circumferential portion that defines an outer circumferential end of a molding cavity, wherein the inner circumferential portion of said outer circumferential stamper holder is provided with a projecting portion having an acute cross-section that consists of a smooth surface projecting into said molding cavity toward said stamper holding portion, wherein an acute cross-sectional angle of said projecting portion is 30–60°, an amount of projection of said projecting portion from the outermost circumference of said molding cavity is 0.2–1 mm, and a curvature radius of a smoothly formed surface of said inner circumferential portion is 0.1–0.8 mm.