METHOD OF MANUFACTURING AN OPTICALLY READABLE DISC RECORD

摘要

A disc-shaped information carrier (1) is formed by welding two injection-moulded plastics discs concentrically to each other (1A, 1B), which discs are manufactured by means of a method comprising the manufacture of a matrix (9), which matrix is formed with recesses (6) which form projections (5A, 5B) on the disc during injection-moulding and which are fused to the facing disc during welding. Said recesses are formed in the matrix by pressing an indenter pin (7) having a pointed end (8) into the matrix surface, to form locally pit-shaped recesses each surrounded by a ridge (11) of displaced material, which ridge has a volume which is substantially equal to the volume of the pit-shaped recess, so that during injection-moulding the disc is provided with a corresponding pin-shaped projection which is surrounded by a groove (12) which can receive the volume of that part of the pin which is melted during welding.