| 摘要 |
PURPOSE:To set the initial permittivity of a demagnetizing apparatus to non- directionality by applying a revolving magnetic field obtained by supplying currents of different phases to a plurality of coils for generating magnetic fields of different directions to a magnetic unit. CONSTITUTION:A sinusoidal voltage from an oscillator 10 is input together with an exponential attenuation curve from an e<-taut> generator (where tau is an attenuation coefficient) 11 to a multiplier 12 to become a waveform of attenuation sinusoidal wave sinomegat.e<-taut>. Part of the output voltage of the multiplier 12 is advanced by 90 deg. by a 90 deg. phase unit 15 to become cosomegat.e<-taut>, a demagnetizing current is supplied through power amplifiers to coils Y1, Y2, thereby generating a magnetic field in an X-axis direction. A demagnetizing circuit 18 for supplying demagnetizing currents to the coils converts the attenuation sinusoidal wave into 3-phase AC currents by 120 deg. phase unit 20 and 240 deg. phase unit 21, which currents are adjusted at their levels by power amplifiers 19 and supplied to the coils. Thus, the initial permittivity of the magnetic unit becomes nondirectional. |
