US 6,556,367 B2Granted

Storage apparatus and position sensitivity setting method

AssigneeFujitsu Limited

InventorEisaku Takahashi

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Abstract

High-accuracy position signals are obtained by correcting nonlinear position sensitivities of two phase signals demodulated from two-phase servo information, into linear ones. A position sensitivity adjusting unit detects the signal level at the intersection of position signals N and Q having different phases by a predetermined track pitch which are demodulated from read signals of two-phase servo information buried and recorded in a disk medium and makes an adjustment of the gain of an AGC amplifier so that the intersection signal level coincides with a predetermined level. A sensitivity correcting unit corrects into linear position sensitivities the nonlinear position sensitivities approximated by sine functions or cosine functions relative to the actual track position X of the two position signals N and Q output from the AGC amplifier.

Claims9

Dependent claims

A storage apparatus comprising:

a position sensitivity adjusting unit which detects the signal level at the intersection of position signals N and Q having different phases φ by a predetermined track pitch (TP/n) which are demodulated from read signals of two-phase servo information buried and recorded in a disk medium, said position sensitivity adjusting unit making an adjustment of the gain of an AGC amplifier so that said intersection signal level coincides with a predetermined level;
and
a sensitivity correcting unit which corrects nonlinear position sensitivities relative to the actual track position X of two position signals N and Q output from said AGC amplifier, into linear position sensitivities,
wherein said sensitivity correcting unit approximates two position signals N and Q relative to the actual track position X output from said AGC amplifier by cosine functions
N=cos X
Q=cos (X−TP/n)
said sensitivity correcting unit defining linear functions of two position signals Na and Qa which are corrected relative to the actual track position X, as
Na=X
Qa=X−TP/n
to thereby obtain relational expressions of the two
N=cos Na
Q=cos Qa
said sensitivity correcting unit figuring out said corrected position signals Na and Qa from said relational expressions as
Na=cos−1 N
Qa=cos−1 Q
to thereby correct nonlinear position sensitivities into linear ones.

13 more elements

A storage apparatus comprising:

a position sensitivity adjusting unit which detects the signal level at the intersection of position signals N and Q having different phases Ø by a predetermined track pitch (TP/n) which are demodulated from read signals of two-phase servo information buried and recorded in a disk medium, said position sensitivity adjusting unit making an adjustment of the gain of an AGC amplifier so that said intersection signal level coincides with a predetermined level;
a sensitivity correcting unit which corrects nonlinear position sensitivities relative to the actual track position X of two position signals N and Q output from said AGC amplifier, into linear position sensitivities;
and
wherein said sensitivity correcting unit approximates two position signals N and Q relative to the actual track position X output from said AGC amplifier by sine functions
N=sin X
Q=sin (X−TP/n)
said sensitivity correcting unit defining linear functions of two position signals Na and Qa which are corrected relative to the actual track position X, as
Na=X
Qa=X−TP/n
to thereby obtain relational expressions of the two
N=sin Na
Q=sin Qa
said sensitivity correcting unit figuring out from said relational expressions said corrected position signals Na and Qa as
Na=sin−1 N
Qa=sin−1 Q
to thereby correct nonlinear position sensitivities into linear ones.

13 more elements

Dependencies are inferred from the claim text.