| 摘要 |
PURPOSE:To prevent the increase of the birefringence of a disk carrier substrate by putting or applying a rubber elastic matter between a hub which fixes an optical disk to a disk driving device and a surface where the hub has a contact with an optical disk substrate. CONSTITUTION:The two recording media having the record layers formed on each substrate are put together by an adhesive or an ultrasonic welding process so that the record layers are set opposite to each other via spacers 6 and 6'. In such a constitution, the optical disk of an air sandwich structure containing hubs is obtained. The rubber elastic matters 8 and 8' are put or applied between the surfaces where the hubs 2 and 2' which fix an optical disk to a disk driving device have contacts with optical disk substrates 4 and 4'. Thus the elastic matters 8 and 8' are provided between hubs 2/2' and substrates 4/4' in order to reduce the stress produced by the heat expansion. As the rubber elastic matter silicone rubber, urethane rubber, neoprene rubber etc., are used. Thus it is possible to prevent the deterioration of performance of the optical disk owing to the attachment of hubs without substantially increas ing the birefringence of the disk. |
