Abstract: A magneto-optical recording medium includes a first magnetic layer which becomes an in-plane magnetization film at room temperature, and a perpendicular magnetization film at a temperature between room temperature and the Curie temperature of the layer, a second magnetic layer which has a Curie temperature lower than the Curie temperature of the first magnetic layer, remains a perpendicular magnetization film from room temperature to its Curie temperature, and is stacked on the first magnetic layer, and a third magnetic layer which is arranged between the first and second magnetic layers and has a Curie temperature lower than the Curie temperatures of the first and second magnetic layers. The first magnetic layer is magnetostatically coupled with the second magnetic layer in a region where the temperature of the third magnetic layer has reached the Curie temperature or more. An information reproduction method of reproducing information from the medium is also disclosed.

Abstract: In an optical information recording/reproducing apparatus, while a magnetooptical recording medium formed by stacking at least a recording layer, which consists of a perpendicular magnetization film for magnetically holding information, and a reproducing layer is rotated at a fixed angular velocity, a laser beam is applied to the medium from the reproducing layer thereby reproducing information held by the recording layer by transferring the information to the reproducing layer. First, information which indicates a relation of an optimum intensity of the laser beam in reproduction with respect to a radial position on the recording medium, previously recorded on the recording medium, is reproduced. Then, the intensity of the laser beam is adjusted on the basis of the information indicating the relation of the optimum intensity of the laser beam with respect to the radial position on the recording medium.

Abstract: In an automatic gain control device, an error signal generated based on output signals from a divided sensor is inputted to an operational amplifier. A sum signal of the output signals from the divided sensor is inputted to a multiplier. The error signal is divided by the sum signal by negatively feeding back an output signal from the operational amplifier to the operational amplifier via the multiplier. Two predetermined voltages are alternately applied to the multiplier in a state in which the sum signal is 0. The amplitudes of output signals from the automatic gain control device corresponding to the two voltages are detected. Input offsets of the operational amplifier and the multiplier are cancelled by calculating the input offsets of the operational amplifier and the multiplier on the basis of the detected amplitudes of the signals, the two predetermined voltages, and a gain of the multiplier.

Abstract: An information recording and/or reproducing apparatus comprises a head section to record and/or reproduce information onto/from an information recording medium having a shape other than a circular shape, holding device for holding the information recording medium and rotating the medium, moving device for moving the holding device in a predetermined direction, detecting device for detecting a rotating position of the information recording medium held to the holding device, and control device for controlling movable guide device in correspondence to a signal from the detecting device.