| 摘要 |
PURPOSE:To correct satisfactorily deterioration of a high band frequency component of a reproducing signal and distortion of a recording pit, and to improve remarkably an eye aperture rate of a waveform by cascade-connecting a cos equalizer of a phase straight line and an asymmetrical transversal equalizer for correcting an asymmetrical waveform distortion. CONSTITUTION:As for a cos equalizer, its phase characteristic becomes a straight line, and this frequency characteristic compensates almost satisfactorily a frequency characteristic of an optical recording and reproducing system. A delay line 18 is provided with three intermediate taps of the first terminal, the second terminal and the third terminal whose delay time is t1, t2 and t3 (t1<t2<t3), respectively, and when an attenuation ratio K1 and K2 of voltage attenuating elements 20, 21 are set as K1>K2, the waveform is improved so that a rise time and a fall time of an equalization reproducing output 103 of a differential amplifier 19 become almost equal. Also, an eye aperture rate becomes the maximum by changing an attenuation ratio K of a voltage attenuating element 17 by control voltage 105 generated from a track address signal. Also, a variation of amplitude of the equalization reproducing output 103 by a value of the attenuation ratio K is corrected by changing the gain of a gain variable amplifier 14. |
