Yasumori Hino

Signal Qualification Method for Partial-Response Maximum-Likelihood Read/Write Channel

The partial-response maximum-likelihood (PRML) signal processing technique is effective for high-density recording media. However, there are few omit evaluation methods for qualifying the played-back signal using a simple measurement tool such as a jitter meter. We propose a simpler PRML qualification method, the so-called maximum-likelihood sequence error (MLSE) detection method. In this paper, we show the validity of the new method for dual-layer Blu-ray Disc read channel and, furthermore, show the method for optimizing the write channel.

Physical Characteristics and Format of a Two-Inch-Diameter Magneto-Optical Disk System with 3 GB Capacity

Recording at a high density four times that of a current digital versatile disk random access memory (DVD-RAM) has been achieved by applying the domain wall displacement detection (DWDD) technology using a conventional optical head with the same wavelength of 660 nm and numerical aperture (NA) of 0.60 as those the DVD head. It has been confirmed by using an alternating sampled servo, laser annealing of the inter track area and partial response maximum likelihood (PRML) that a recording density of 15 Gbit/inch2 with a track pitch of 540 nm and bit length of 80 nm has sufficient system margins. A newly developed 1-bit-distributed address format has achieved a redundancy of 23%. Furthermore, the edge shift compensation technique has reduced the recording magnetic field. These indicate that a capacity of 3 GB on a two-inch-diameter disk is now available for mobile use. If applied to a digital video camera, one hour or more of moving-picture-experts-group-2 (MPEG2) video contents can be recorded at a bit rate of 6 Mbps.

One-Path Calibration Method of Write Strategy using Simultaneous Linear Equations

Write strategy optimization is desirable for expanding system margins. However, this process is very complex and time-consuming. We propose one-path calibration method of write strategy using simultaneous linear equations for Blu-ray disc. In this method, write pulse compensation on mark deviation is expressed clearly by two simple linear equations. Experimental results using these linear equations show that the write strategy is optimized after only one-path test recording. Thus, with the new method, it is possible to reduce the number of test recordings and to save test recording areas.