Teruo Furukawa

High density recording method for magneto-optical disk

A recording and reproducing method using a new modulation code has been developed to increase the capacity of optical disk drives. For two recording and reproducing methods that use the new code and the 4/15 modulation code, respectively, the detection jitter and the bit error rate at various recording densities are described. Experimental results using a 130-mm magnetooptical disk drive show that recording with the new code greatly increases the linear bit density of the disk drives. >

Pit phase compensating method for sample servo optical disk drive

A novel recording-reproducing method has been developed to eliminate the phase deviation of reproduced data signals from magnetooptical (MO) pits from the demodulation clock for sampled-servo-format rewritable optical disk drives. The magnitude of the phase shift was found by simulation and confirmed by experiments. The phase error required to keep demodulation error rate below a specific value was also found. The method consists of writing extra MO domains in the leading segment of a sector to be recorded before data are recorded. The domains are reproduced to determine the adequate amount of phase compensation when data are read. An evaluation of the proposed recording-reproducing method showed that the pit phase compensation method is effective for use in MO disk drives. >