| 摘要 |
PURPOSE:To improve the reliability of writing and reading operation by performing adaptive control over the light quantity power of write laser light to and that of read laser from a write and read area according to a radial position on a disk. CONSTITUTION:A switching circuit 19 is switched to the side of a contact a2 in, for example, playback mode with a switching control signal and initial data is read out of a recording area and stored in a memory 23. In a readout operation state, switching circuits 19 and 27 are switched to sides of contacts a2 and b2 with the switching control signal to supply a readout output RD to a light quantity power control circuit 17 and a setting circuit 28 is controlled with a setting signal 13 obtained from the initial data stored in the memory 23, so that a comparing circuit 18 generates a control signal S5 which controls the control circuit 17 so that the light quantity power varies according to a constant curve as laser light scans on the innermost diameter part, intermediate part, and outermost diameter part of the write and read area. Consequently, the reliability of writing and reading operation is further improved. |
