| 摘要 |
PURPOSE:To improve the protection function of a protection layer of a substrate for a single plate type optical recording medium by providing the outermost peripheral part of the substrate with the level difference or roundness. CONSTITUTION:The level difference 4 or roundness 51 are provided for the outer peripheral part of the substrate for the optical recording medium 1. It is preferred that the level difference 4 is 0.03-0.4mm from the recording layer surface 3, the width 7 of the level difference is 0.2-0.7mm, and the tilt angle 8 of a substrate outer peripheral side face 6 and the level difference face 5 is 20-70 degrees. The radius 53 of roundness 51 is desirable to be 0.2-1.0mm. Thus, the protection layer can easily, overall and partly infiltrate the outer peripheral side face of the substrate with a spin coating method so that the protection layer hardly breaks away and the protection function is improved. |
