Patent ID: 7277364

Claim:
A magneto-optical recording medium device for at least reproducing information from a magneto-optical recording medium, comprising: an optical head irradiating a light beam onto the magneto-optical recording medium; and a bias magnetic field generator applying a bias magnetic field to the magneto-optical recording medium, wherein a peak position of the bias magnetic field applied by the bias magnetic field generator deviates from the center of a light beam spot irradiated onto the magneto-optical recording medium in a predetermined direction; wherein the bias magnetic field generator is structured of an electromagnet which includes a yoke extending along the radius direction of the magneto-optical recording medium and a coil wound around the yoke; wherein a cross section of the yoke in the radius direction is left-right asymmetric on the magneto-optical recording medium; and wherein the bias magnetic field generator is positioned so that the center position of the yoke in the approximate track direction coincides with the center position of the light beam spot in the approximate track direction.