| 摘要 |
PURPOSE:To reduce the birefringence generated in a substrate and to improve the reliability of an optical disk device by fixing the optical disk substrate and an engagement positioning member only in the central hole part of the substrate. CONSTITUTION:The optical disk substrate 1 and the engagement positioning member 2 are fixed without using a whole contact surface as usual, fixed only by the central hole part of the substrate 1 and the cylindrical part of the positioning member 2. Thus, the stress on the optical disk substrate 1 in case of solidifying of the adhensive and thermal expansion caused by the temperature change of usage environment is reduced, and the occurrence of birefringence can be reduced. Consequently, the deterioration of a signal does not occur and a reading error is also hard by generated, whereby the reliability of the optical disk can remarkably be improved. |
