Patent ID: 7555205

Claim:
A defect management method for an optical disc on which main information is recorded by forming optically-readable recording marks, and on which sub information is recorded by superimposing the sub information on the main information, the optical disc defect management method comprising: a recording step of recording the main information in a recording area of the optical disc by forming the recording marks on the optical disc, and recording the sub information by superimposing the sub information on the main information, the sub information being recorded using phase modulation to displace edge positions of the recording marks; a verification step of judging whether or not the main information and the sub information have been recorded normally, every time a predetermined amount of main information and sub information are recorded, and when it is judged that at least one of the main information and the sub information has not been recorded normally, regarding the recording area as a defective area related to a recording of one of (i) the main information, (ii) the sub information, and (iii) the main information and the sub information; and a defective area management step of performing the following processes when it is judged in the verification step that at least one of the main information and the sub information has not been recorded normally: relocating and recording the sub information in a predetermined spare area of the optical disc; and registering, into a predetermined defect management area of the optical disc, information that associates the defective area with a replacement area inside the spare area to which the sub information in the defective area has been relocated.