Magneto-optic recording system with overwrite capability

Abstract

An overwritable magneto-optic recording system has a recording medium with a substrate, a recording magnetic film and a reproducing magnetic film deposited on the substrate. The reproducing magnetic film has a Curie temperature lower than that of the recording magnetic film, and coercive force Hc higher than that of the recording magnetic film. In a write process, a magnetic head writes data magnetically on the recording magnetic film, then, in a transfer process, an optical head (which is positioned downstream along the relative movement of the recording medium and the optical head) heats the recording medium higher than the Curie temperature of the reproducing magnetic film so that the reproducing magnetic film loses its magnetic property. During the cooling period after heating, recorded bits in the recording magnetic film are transferred to the reproducing magnetic film which restores its magnetic property. In the reproducing process, the optical head irradiates the reproducing magnetic film by a polarized coherent beam, and the data is reproduced on the principle that the polarization of the reflected beam depends upon the recorded data based on the Kerr effect. Thus, the high speed recording defined by a magnetic recording, and high density recording defined by an optical recording are obtained. Overwrite is possible merely by writing data by the magnetic head as in the case of the write process.