| 摘要 |
PURPOSE:To prevent the deflection of an optical disc surface and to realize accurate recording and reproduction, by placing concentrically a deflection correcting disc having higher rigidity than that of the optical disc in contact on the optical disc and tightening the rotation center together to rotate the two in one body. CONSTITUTION:There is a minute gap corresponding to the deflection of the optical disc 1 on the contact surface between the optical disc 1 fixed to a spindle 4 and the surface deflection correcting disc 3, and the air in the gap is exhausted toward the outside with the centrifugal force in rotating the disc. Further, the rotation center of the inner circumference of the optical disc 1 and the deflection correcting disc 3 is adhered closely with a disc fitting section of the spindle 4 and a tightening ring 11 and no air is supplied to the said gap. Thus, the inside of the gap is at a negative pressure in rotation and an external force for adherling both the discs closely is exerted. Thus, the optical disc 1 having low rigidity is adhered closely to the deflection correcting disc 3 having the higher rigidity and the warp of the optical disc 1 is reduced remarkably. |
