| 摘要 |
<p>The apparatus and method is used for recording optical information on an optical disk and reproducing the optical information therefrom by the use of an optical beam. The system is especially adapted to eliminate crosstalk from nearby tracks even when the position of the beam spot fluctuates with respect to a desired track and even when the size of a beam spot incident to the desired track is varied. The apparatus particularly comprises a frequency characteristic converter which receives output signals from a photodetector array (11). The photodetector array (11), for example, comprises 3 photodetectors (100, 101, 102) receiving input beams (130, 131 and 132). The photodetector (100) is associated with a desired track for reproducing a signal, whereas photodetectors (101, 102) are associated with neighbouring tracks for reproducing a replica of crosstalk. The frequency characteristic convertor (12) further comprises transversal filter means (110, 111, 112), each capable of controlling a frequency characteristic, an adder (120), a reference signal generator (121), an error detector (122), a filter control circuit (123) for controlling the filters (110, 111, 112), a timing control circuit (124), a decision circuit (125), a switch (126) and an output terminal (133). The output of the photodetector (100) adapted to reproduce a signal is fed to the timing control circuit (124), which detects the beginning of a preamble signal written in the track beforehand and delivers a control signal to the reference signal generator (121) and switch (126). When the timing control circuit (124) detects the end of the preamble signal, it delivers a control signal to the reference signal generator (121) and switch (126). The characteristic control for the transversal filters (110, 111, 112) is sequentially performed on the basis of the preamble signal and the corresponding reference signal and on the basis of an input signal and an output signal of the decision circuit (125).</p> |
