| 摘要 |
PURPOSE:To deform characters and graphic patterns through a copying by forming pit patterns for characters or graphic patterns having such a size that they are visibly recognized on a recording surface by the difference in optical reflectivity and making the line width to be less than 0.5mm. CONSTITUTION:Visibly recognizable characters and graphic patterns are displayed on the signal surface of a CD-ROM 4 of an original disk. These characters and graphic patterns are either a linear shaped pattern 21 or a character pattern 211. These patterns 21 and 211 are recognized as pattern regions. For a CD-ROM, data are modulated by an EFM system commonly used for a music CD and are recorded on a signal surface using a CLV system or a CAV system. Visualy recognizable characters and graphic patterns are formed by using the difference in optical reflectivity of a pit section and a non-pit section. A CD reproducing device is capable of perfectly reproducing data even though a disk has a scratch having a 1.7mm width. Therefore, the line widths of the patterns 21 and 211 are made less than 1.7mm. Thus, the recognition of an original optical disk among copied disks is easily accomplished by the presence or the absence of the characters and graphic patterns. |
