| 摘要 |
PROBLEM TO BE SOLVED: To calculate the deterioration with time of the quality of data recorded on an optical disk in a short time, and to calculate a preservable time of the recorded data.SOLUTION: When user data U are recorded on a data area 200 of an optical disk 101, a test signal T including a component in which a signal level is smaller than a reference value is recorded on a test area 210. Then, the test signal T is reproduced from the test area when a predetermined time has passed, to calculate the quality degradation of the user data U from the evaluation result. Alternatively, every time when the user data U are recorded and reproduced on/from the data area 200, the test signal T is recorded and reproduced repeatedly on/from the test area 210. Then, the test signal T is reproduced from the test area at predetermined timing to calculate the quality deterioration of the user data U from the evaluation result. |
