Method of providing a substrate of an optically readable information disc with an optically detectable structure.

摘要

© The invention relates inter alia to a method of providing a substrate with a centred optically detectable structure, such as a servo structure on a transport substrate of an optical information disc, which method uses a mould (1) having a base (1A) carrying a mould structure (2) which is covered with a reproduction layer (4), for example of a transparent radiation-curable resin, which after curing is detached from the mould together with the substrate. In its centre the base (1A) of the mould is provided with base-centring means (7) relative to which the mould structure is centred accurately. Before it is placed on the mould a substrate (3) is provided with a disc hub (8) comprising separate disc-centring means (9) which serve to centre the finished information disc (17) on the drive spindle (27) of a drive apparatus. The intermediate product comprising the substrate (3) and the disc hub (8) is centred on the base (1A) of the mould by cooperation between the base-centring means (17) and the disc-centring means (9). This may be effected by the use of an auxiliary centring means (12) which is in contact with a wall (14) of a central centring hole (11) in the disc hub (8) and with a wall (13) of a central centring recess (10) in the base (1A). Thus, the reproduction layer is cured in the position which is thus centred without any play, after which the substrate together with the disc hub is detached from the mould without the centring of the servo track on the substrate being disturbed.