| 摘要 |
PURPOSE:To obtain easily an optical disk which is free from a recording/ reproduction error despite the large number of using times, by engaging an outer circumferential spacer with a circular substrate, and also forming a project ed part at the outer end part of the substrate surface at the side opposite to a hollow part. CONSTITUTION:A projection is formed at the outer end part by an engagement type outer spacer 10 in order to prevent the rubbing on a surface 11. Thus this optical disk has no flaw despite the large number of using times, therefore, no recording/reproduction error of information occurs. In addition, said projec tion part is unified with the spacer 10, reduction of cost and easy production are realized at the optical disk. |
