Abstract: A magneto-optical disk system includes a magneto-optical disk and a disk drive. The magneto-optical disk drives provides a function of controlling the shape of a recorded domain by using a short wavelength laser beam and a test recording and a function of recording a using a pulse train. The magneto-optical disk has a laminated layer structure capable of obtaining a high S/N ratio and stabilizing a heat conduction. The magneto-optical disk drive with the recorded domain shape control function using a short wavelength laser beam and a test recording and with the pulse train recording record function is organically coupled with the magneto-optical disk having the laminated layer structure with a stabilized heat conduction to make the disk and the disk drive have an integrity therebetween, providing a magneto-optical disk having a recording capacity four times as large as the first generation magneto-optical disk system.

Abstract: A magneto-optical disk recording control method using the mark length recording method wherein the marks and gap regions between marks are recorded on the surface of the disk by maintaining a constant temperature distribution during the recording. The laser is driven to a non-recording level in gap regions between marks that exceed a base recording level used for reproduction of the marks. When a mark is recorded, the laser power is increased to a recording power level and after the mark has been recorded, the laser power level is reduced to the base power level, followed by being raised to the gap recording level. Control of the laser is performed by superposing a plurality of pulse trains that are synchronized with respect to a clock having a cycle T. The pulse trains are derived from the code train to be recorded and have pulses with a duration that is an integral multiple of (1/2)T.

Abstract: A signal processing method for recording and playing back recorded data with decreased detection errors originating from residual marks characteristic of an overwrite medium is performed by 8/9 modulating input data, and by inverting the polarity of the modulated data string at each "1" bit to produce a DC-free recording pulse. The thus-recorded signal is played back through a playback equalizer 8 before being converted by an A/D converter 9 into digitized amplitude data. The digitized data are processed to determine an identification level, which identification level is stored as well as used to determine displacement quantities for quantized bits derived from the analog playback signal. The number of "1" bits is counted by a counter 20, and an error in the number of "1" bits is detected by a comparator 21.

Abstract: A tape recorder of the present invention comprises a pair of feed and take-up spools for winding a tape as recording media, a rotatable drum rotated to wind and run the tape between the pair of spools over the drum surface helically, a head for recording, reproducing or erasing signals on the tape wound over said drum surface, and control means for controlling the relative positional relationship between the head and the tape wound over the drum surface based on an error signal such that said signals are stably recorded, reproduced or erased along a desired track, the control means having means for holding the error signal during the period in which the tape is discontinued over a drum surface.

Abstract: An optical tape apparatus having improved focus and tracking control. An optical head records, reproduces, or rewrites data on an optical tape by helically scanning the tape with a laser beam. A guide plate is disposed between the optical head and the tape to prevent the beam from becoming unfocused due to fluctuation of the tape cuased by an air film between the optical head and the tape. The optical head contains a semiconductor laser and an optical system exhibiting chromatic aberration for directing the laser beam onto the tape. The optical system includes a condenser lens for focusing the beam onto the tape. Fine focus control is achieved by changing the wavelength of the laser beam by directing part of the beam reflected from the tape back to the laser, thereby changing the focal point of the beam by virtue of the chromatic aberration of the optical system.