| 摘要 |
PURPOSE:To adjust quickly a magnet for a bias magnetic field to an optimum magnetized state by converting and setting a difference value in a magnetizing operation of the previous time of a target bias magnetic field, to a magnetizing set value, from a magnetizing quantity per unit set value, and executing the magnetizing operation. CONSTITUTION:Magnetization is executed by voltage V1. Subsequently, a direct current value supplied to a bias magnetic field adjusting coil is varied, whether a magnetic bubble memory is operated correctly or not is checked at every stage, and a lower limit value LH1 of a bias magnetic field in a magnetized state is measured. Subsequently, a lower limit value LH2 of the bias magnetic field is measured by increasing the demagnetizing voltage from V1, and demagnetizing a permanent magnet by the demagnetizing voltage V2. From the lower limit value of the bias magnetic field derived by the magnetizing operation of said two times, a variation amount alpha of the lower limit value per unit demagnetizing voltage is derived, also demagnetizing voltage Vn+1 in magnetization of the next time is derived by substituting alpha in the expression, and the magnetizing operation is executed. Subsequently, a lower limit value LH3 of the bias magnetic field is derived, and a difference to a target bias magnetic field lower limit value TH0 is converged to a prescribed value or below. |
