Waveform equalizing circuit

Claim 2

A waveform equalizing circuit for use in a magnetic recording device for reproducing signals through a selected one of a plurality of head means for reproduction from a magnetic recording medium where signals are recorded, comprising: means for deriving a reproduced signal including means for calculating an output resolution from the signals reproduced from the selected one of said plurality of head means, and means for comparing the output from the calculating means with at least one predetermined value, means for attenuating the signal reproduced by the selected one of said plurality of head means by a predetermined amount, means for delaying the signal reproduced by the selected one of said plurality of head means by a predetermined amount, the predetermined amount in at least one of said attenuating means and said delaying means being made variable on the basis of the output from said reproduced signal deriving means, and differential means for receiving the signals passed through said attenuating means and said delaying means.

Claim 3

A waveform equalizing circuit according to claim 1, wherein said reproduced signal deriving means includes an A/D converter for sampling two signals having different predetermined frequencies from the reproduced signal and digitizing the two signals, said calculating means including a divider for calculating the output resolution in accordance with the two signals, and said comparing means including a comparator for comparing the output from the divider with the at least one predetermined value.

Claim 4

A waveform equalizing circuit according to claim 1, wherein said attenuating means comprises a plurality of attenuators having attenuation amounts different from one another, and means for selecting the attenuator having a predetermined attenuation amount from said plurality of attenuators on the basis of the output from said reproduced signal deriving means.

Claim 5

A waveform equalizing circuit according to claim 1, wherein said delaying means comprise a plurality of delay lines having delay amounts different from one another, and means for selecting the delay line having a predetermined delay amount from said plurality of delay lines on the basis of the output of the reproduced signal.

Claim 6

A waveform equalizing circuit according to claim 1, wherein the magnetic recording device is a magnetic disc device including a rotary magnetic disc wherein signals are recorded and reproduced from different tracks on the rotary magnetic disc.

Claim 7

A waveform equalizing circuit according to claim 5, further comprising means for producing a head selection signal for selection of one of said plurality of head means for reproduction.

Claim 8

A waveform equalizing circuit for use in a magnetic recording device for reproducing signals through a selected one of a plurality of head means for reproduction from a recording medium where signals are recorded and including means for producing a head selection signal for selection of one of said plurality of head means for reproduction, comprising: means for attenuating the signal reproduced by the selected one of said plurality of head means by a predetermined amount, said attenuating means including a plurality of attenuators to be selected on the basis of said head selection signal, means for delaying the signal reproduced by the selected one of said plurality of head means by a predetermined amount, said delaying means including at least one delay line to be selected on the basis of said head selection signal, the predetermined amount in at least one of said attenuating means and said delaying means being made variable on the basis of said head selection signal so that the predetermined amounts in said attenuating means and said delaying means are kept constant while the same head means selected by said head selection signal is used for reproduction to thereby compensate for variations in characteristics of different ones of said plurality of head means, and only one differential amplifier for receiving signals passed through the respective selected ones of said attenuating means and said delaying means.

Claim 9

A waveform equalizing circuit for use in a magnetic recording device for reproducing signals through a selected one of a plurality of head means for reproduction from a recording medium where signals are recorded and including means for producing a head selection signal for selection of one of said plurality of head means for reproduction, comprising: means for attenuating the signal reproduced by the selected one of said plurality of head means by a predetermined amount, said attenuating means including a plurality of attenuators to be selected on the basis of said head selection signal, means for delaying the signal reproduced by the selected one of said plurality of head means by a predetermined amount, said delaying means including at least one delay line to be selected on the basis of said head selection signal, the predetermined amount in at least one of said attenuating means and said delaying means being made variable on the basis of said head selection signal so that the predetermined amounts in said attenuating means and said delaying means are kept constant while the same head means selected by said head selection signal is used for reproduction to thereby compensate for variations in characteristics of different ones of said plurality of head means, and only one differential amplifier for receiving signals passed through the respective selected ones of said attenuating means and said delaying means.

Claim 10

A waveform equalizing circuit according to claim 7, wherein said plurality of attenuators have attenuation amounts different from one another, and means for selecting one attenuator having a predetermined attenuation amount from said plurality of attenuators on the basis of said head selection signal.

Claim 11

A waveform equalizing circuit according to claim 7, wherein said delaying means comprises a plurality of delay lines having delay amounts different from one another, and means for selecting one delay line having a predetermined delay amount from said plurality of delay lines on the basis of said head selection signal.

Claim 12

A waveform equalizing circuit according to claim 7, wherein the magnetic recording device is a magnetic disc device including a rotary magnetic disc wherein signals are recorded and reproduced from different tracks on the rotary magnetic disc.

Claim 13

A waveform equalizing circuit for use in a magnetic recording device for reproducing signals through a selected one of a plurality of head means for reproduction from a recording medium where signals are recorded and including means for producing a head selection signal for selection of one of said plurality of head means for reproduction, comprising: a plurality of attenuators having different amounts of attenuation from one another, each attenuator enabling attenuation of a signal reproduced by the selected one of said plurality of head means by a predetermined amount on the basis of said head selection signal; at least one delay line enabling delay of the signal reproduced by the selected one of said plurality of head means by a predetermined amount on the basis of said head selection signal; first switching means for selecting one of said plurality of attenuators; second switching means for selecting one of said at least one delay lines; and only one differential amplifier for receiving the signals passed through the respective selected ones of said attenuator selected by said first switching means and said delay line selected by said second switching means.

Claim 14

A waveform equalizing circuit for use in a magnetic recording device for reproducing signals through a selected one of a plurality of head means for reproduction from a recording medium where signals are recorded and including means for producing a head selection signal for selection of one of said plurality of head means for reproduction, comprising: a plurality of attenuators having different amounts of attenuation from one another, each attenuator enabling attenuation of a signal reproduced by the selected one of said plurality of head means by a predetermined amount on the basis of said head selection signal; at least one delay line enabling delay of the signal reproduced by the selected one of said plurality of head means by a predetermined amount on the basis of said head selection signal; first switching means for selecting one of said plurality of attenuators; second switching means for selecting one of said at least one delay lines; and only one differential amplifier for receiving the signals passed through the respective selected ones of said attenuator selected by said first switching means and said delay line selected by said second switching means.

Claim 15

A waveform equalizing circuit according to claim 11, wherein said first and second switching means are switched in response to said head selection signal.

Claim 16

A waveform equalizing circuit according to claim 11, wherein said first and second switching means are switched in response to an output from a reproduced signal deriving means including means for calculating an output resolution from the signals reproduced from the selected one of said plurality of head means and means for comparing the output from the calculating means with at least one predetermined value.

Claim 17

A waveform equalizing circuit according to claim 13, wherein said reproduced signal deriving means includes an A/D converter for sampling two signals having different predetermined frequencies from the reproduced signals and digitizing the two signals, said calculating means including a divider for calculating the output resolution in accordance with the two signals, and said comparing means including a comparator for comparing the output from the divider with the at least one predetermined value.

Claim 18

A waveform equalizing circuit according to claim 11, wherein the magnetic recording device is a magnetic disc device including a rotary magnetic disc wherein signals are recorded and reproduced from different tracks on the rotary magnetic disc.

Claim 19

A waveform equalizing circuit according to claim 11, wherein the different amounts of attenuation and delay are coordinated with the different ones of said plurality of head means so as to compensate for variations in characteristics of the different ones of said plurality of head means.