| 摘要 |
PURPOSE:To avoid an error due to the damage of a disk, a drop-out, etc. and to attain the satisfactory tracking servo by sampling and synthesizing the output amplitude given from a detector which delivers a phase difference component signal to obtain a tracking error signal. CONSTITUTION:The output of a 4-split photodetector 11 is turned into two phase difference component signals S1 and S2 by a phase difference component signal generating circuit 12 consisting of two adders which obtain the sum of each diagonal component and then led to both input terminals of a phase difference detector 13 as well as correspondingly to an input terminal of each of multipliers 14 and 15 respectively. Here the corresponding multiplications are performed between signals S1 and S2, and these signals are supplied to both input terminals of an adder/subtractor 16 via LPFF1 and F2. In such a way, a multiplication is carried out with the amplitude component to prevent the generation of a wrong tracking error signal. |
