Patent ID: 6424602
Filing Date: 2002-07-23
Classification: G11B

Abstract:
A magneto-optical reproducing apparatus for reproducing information recorded on a magneto-optical medium comprising a transparent substrate and a first magnetic layer, a second magnetic layer and a third magnetic layer sequentially laminated on the transparent substrate in that order, where each of the first magnetic layer, the second magnetic layer and the third magnetic layer comprises a magnetic film and has a domain wall coercivity, a domain wall displaceability and a Curie temperature characteristic, and where the first magnetic layer has a smaller domain wall coercivity and greater domain wall displaceability at ambient temperature and temperature close to ambient temperature than the third magnetic layer, and the second magnetic layer has a Curie temperature lower than the first magnetic layer and the third magnetic layer, the apparatus comprising:an optical system that irradiates the medium with a light beam, where a spot size of the light beam is greater than a pitch of the medium, and where domain walls of a magnetic domain for information formed on the medium are displaced by the irradiation with the light beam; a photosensor that detects a change in a polarization direction of reflected light of the light beam and outputs a reproduction signal; a differentiating circuit that differentiates with respect to time the reproduction signal output from the photosensor; and a binarizing circuit that generates a binary signal by comparing the signal differentiated in the differentiating circuit with a prescribed threshold value.