Patent ID: 7940485

Claim:
A magnetic reproducing apparatus for reproducing a magnetic data, comprising: a magnetic disk having a plurality of tracks on which recording bits are sequentially recorded at regular intervals, each of the recording bits generating a magnetic field; a rotating part rotating the magnetic disk; and a magnetic head having a spin-torque oscillator which reads a change of the magnetic field generated from the recording bits depending on the rotation of the magnetic disk, and generates an output signal having an oscillation frequency which is sequentially changed depending on the rotating magnetic disk, the magnetic data recorded on the magnetic disk being reproduced from the output signal, wherein the following equation is satisfied:  ω 0 ⁢ T - Round ⁡ [ ω 0 ⁢ T π ] ⁢ π  < arccos ⁡ ( 10 G 20 ⁢ 1 - ⅇ - πΔ ⁢ ⁢ fT ) ⁢ ⁢ and ⁢ ⁢  ( ω 0 + Δω shift ) ⁢ T - Round ⁡ [ ( ω 0 + Δω shift ) ⁢ T π ] ⁢ π  ⁢ < arccos ⁡ ( 10 G 20 ⁢ 1 - ⅇ - πΔ ⁢ ⁢ fT ) ( 1 ) where ω o indicates an oscillation frequency of the spin-torque oscillator, Δω shift the frequency shift of the spin-torque oscillator produced by the magnetic field from the magnetic disk, Δf the full-width at half maximum of an oscillation spectrum of the spin-torque oscillator, T a read signal period which corresponds to a time period required for reading one recording bit, Round(X) a function that expresses an integral number closest to a given number X and is replaced by an integral number closest to the given number X in Equation 1, and G a constant greater than the signal-to-noise ratio of a desired read output signal of the spin-torque oscillator.