US 5,870,372 A · Adaptive equalizer of recorded information reproducing apparatus

Abstract

To provide an adaptive equalizer of a recorded information reproducing apparatus capable of securing a desired waveform equalizing accuracy with a small circuit scale. The adaptive equalizer includes first delay means for delaying a read sample read and sampled from an optical recording medium by the first delay time shown below and successively outputting the resulting value, second delay means for further delaying the value output from the first delay means by the second delay time shown below and successively outputting the resulting value, third delay means for further delaying the value output from the second delay means by the second delay time and successively outputting the resulting value, fourth delay means for delaying the value output from the third delay means by the first delay time and successively outputting the resulting value, and an equalizer executes adaptive operations based on the read sample output from the first delay means and fourth delay means, input read sample, and a read sample output from the third delay means. {0.6*(.lambda./NA)/V.sub.L }<first delay time+second delay time<{1.0*(.lambda./NA)/V.sub.L } {0.3*(.lambda./NA)/V.sub.L }<second delay time<{0.6*(.lambda./NA)/V.sub.L } . .lambda.: a read beam wavelength V.sub.L : a read linear velocity NA: a numerical aperture of a objective lens

Claims6

Dependent claims

An adaptive equalizer of a recorded information reproducing apparatus provided with a pickup for receiving reflected light when a read beam having a wavelength .lambda. is applied to the recording surface of an optical recording medium through an objective lens having a numerical aperture NA at a read linear velocity V.sub.L and converting the reflected light into electric signal to obtain read signal and an A/D converter for successively sampling said read signal to obtain read sample, the equalizer comprising:

first delay means for delaying said read sample by a predetermined first delay time and successively outputting said read sample;
second delay means for further delaying the value output from said first delay means by a predetermined second delay time and successively outputting the resulting value;
third delay means for further delaying the value output from said second delay means by said second delay time and successively outputting the resulting value;
fourth delay means for further delaying the value output from said third delay means by said first delay time and successively outputting the resulting value;
skew-direction detection means for detecting the direction of a tangential skew occurring between said optical recording medium and said read beam and outputting a skew-direction signal showing the detected skew direction;
selection means for selecting either a first combination or second combination depending on said skew-direction signal, said first combination comprising the value output from said first delay means and the value output from said fourth delay means, said second combination comprising said read sample and the value output from said third delay means;
error operation means for computing the difference between an equalized read sample and a predetermined reference value as an error value;
and
adaptive operation means for computing said equalized read sample by executing adaptive operations based on said error value and the value of the combination selected by said selection means and outputting said equalized read sample;
wherein said first delay time and said second delay time satisfy the following inequalities respectively:
{0.6*(.lambda./NA)/V.sub.L }<said first delay time+said second delay time<{1.0*(.lambda./NA)/V.sub.L }
{0.3*(.lambda./NA)/V.sub.L }<said second delay time<{0.6*(.lambda./NA)/V.sub.L }.

9 more elements

first delay means for delaying said read sample by a predetermined first delay time and successively outputting the resulting value;
second delay means for further delaying the value output from said first delay means by a predetermined second delay time and successively outputting the resulting value;
third delay means for further delaying the value output from said second delay means by said second delay time and successively outputting the resulting value;
fourth delay means for further delaying the value output from said third delay means by said first delay time and successively outputting the resulting value;
first weighting and addition means for weighting and adding said read sample and the value output from said third delay means;
second weighting and addition means for weighting and adding the value output from said first delay means and the value output from said fourth delay means;
error operation means for computing the difference between an equalized read sample and a predetermined reference value as an error value;
and
adaptive operation means for computing said equalized read sample by executing adaptive operations based on the weighted and added values obtained by said first and second weighting and addition means and said error value;
wherein said first delay time and said second delay time satisfy the following inequalities respectively:
{0.6*(.lambda./NA)/V.sub.L }<said first delay time+said second delay time<{1.0*(.lambda./NA)/V.sub.L }
{0.3*(.lambda./NA)/V.sub.L }<said second delay time<{0.6*(.lambda./NA)/V.sub.L }.

9 more elements

Dependencies are inferred from the claim text.

Adaptive equalizer of recorded information reproducing apparatus

Life of this patent

Adaptive equalizer of recorded information reproducing apparatus

Life of this patent

Abstract

Claims6