| 摘要 |
PURPOSE:To attain the tracking control easily and with high accuracy by deforming the boundary between both side walls of a groove for recording track and recording tracking detection signals f1 and f2 independently of each other. CONSTITUTION:The half-width bits 8a and 8b which are modulated by tracking detection signals f1 and f2 are formed on the side walls 7a and 7b of a groove 4 provided for recording track. In a reproduction mode a reading laser beam 6 is irradiated to the entire bottom area of the groove 4. Then the reproduction signal A is supplied to the band pass filters BPF11 and 12 having pass frequencies F1 and F2 respectively. Thus the signals f1 and f2 are extracted. Then a tracking error signal TE is obtained from the difference of wave detection outputs. |
