International Business Machines Corporation

David M Oldham

John Edward Kulakowski

Rodney Jerome Means

Morovat B Tayefeh

A magnetooptic recorder player provides for residual data checking and media defect checking. Media defect checking is effected by comparing the reflected light intensity of a modulated optical beam with the input data characteristics. A difference between the input data and the detected light intensities represents asperities in the record media. Residual data is checked by selectively gating MO detected signals during recording, which are intermediate the high intensity light beam pulses used for recording signals. Both the detected residual data and detected media asperities are counted for each addressable record storage area on the medium.

Checking media operations and recording during optical recording

In method of operating a magnetic recorder, magnetooptic, for example, the erasure direction for successive recording areas (sectors) are determined by the direction of magnetization of prior recording. When the erasure direction is reversed, the direction of remanent magnetiaztion indicating a 'non-erasure', record or information representing direction is also reversed. A mark is placed in each sector for identifying its erasure direction.

Method of recording using selective-erasure directions for magnetooptic

In a magnetooptic record member the erasure direction for successive recording areas (sectors) are determined by the direction of magnetization of prior recording. A mark is placed in each sector for identifying its erasure direction. The mark is preferably a sequence of longer ones, of one-half wavelengths appearing in the recorded information-bearing signals. The erasure and recording directions are reversed such that in the recording direction in a successive recording area equal to the erasure direction of a proceeding area. This selection is based upon the current direction of a magnetic steering field.

Magnetooptic recording member having selectively-reversed erasure

In a magnetic recorder, magnetooptic, for example, the erasure dircetion for successive recording areas (sectors) are determined by the direction of magnetization of prior recording. A mark is placed in each sector for identifying its erasure direction.

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Tucson, AZ, United States of America

David M Oldham