| 摘要 |
PURPOSE:To suppress oscillation amplitude by specifying the outside diameter of an inner peripheral side spacer to >=45mm, the adhesive region between an optical disk substrate and the inner peripheral side spacer to >=45mm and below the outside diameter of the spacer and the length of an unadhered parts for air venting to <=10mm. CONSTITUTION:The outside diameter X of the inner peripheral side spacer 1 is specified to >=45mm and two sheets of the upper and lower optical disk substrates 2 are stuck to each other via the spacer 1 and the outer peripheral side spacer 3. The assurance of the adhesive region of the substrate 2 and the spacer 1 at >=45mm and the size approximately equal to the outside diameter X is more preferable for production. The length Y in the unadhered parts 4 for air venting is acceptably <=10mm and is generally more preferably about 3 to 5mm. Further, the unadhered parts 4 are so provided as to exist in the positions symmetrical with the A surface side and the B surface side. The resonance frequency decreases drastically when the length Y of the unadhered parts 4 exceeds 10mm. The oscillation amplitude of the disk is suppressed to a low level in this way. |
