| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optimum laser power irrespective of an inclination of a record medium by controlling the power of laser beams irradiated to the record medium in accordance with a rotational angle of the record medium. SOLUTION: An MPU 14 forms a test pattern to set a read power when a record medium is inserted or for every predetermined time, and stores the pattern in a buffer memory 20. The MPU 14 erases a sector N to be tested, writes a test pattern in the sector N, turns a laser spot power to a default value, reads the test pattern from the sector N, compares with the test pattern stored in the buffer memory 20, calculates an error rate and stores in a memory therein. A minimum error rate is selected and stored in a read power set table 14a in the MPU 14 for setting a read power offset value of the sector N. The process is repeated for every sector and offset values are set in the table 14a. The read power is controlled by these offset values to read data. |
