Harumitsu Miyashita

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.

Optical disk recording system of 25-GB capacity

A new in-groove format with Saw-Tooth wobble (STW) for blue laser and high NA system is proposed. The STW is designed in order to satisfy for high reliability of the addressing, continuous generation of system clock and easy linking of write data. The format efficiency is high, and moreover, it is confirmed capability for not only single-layer but also dual-layer phase change optical disk. In the conditions of the disk diameter of 120mm, track pitch of 0.32 micrometers and data bit length of 0.116micrometers /bit, the user capacity per layer is achieved 25G-bytes using D8-15 codec and PR(3443)ML channel. The bottom jitter of 9.4 percent by level-slice and the bit-error-rate of 6.0E-6 after PRML are obtained. In addition, the wide stress margins, as the radial/tangential tilt and the defocus tolerances, demonstrate to be enough to realize consumer optical disk systems of the next generation.

High-Density Recording on a Phase-Change Rewritable Disk using a 405 nm Blue Laser Diode

The possibility of a 28 GB capacity/layer has been studied using a blue laser diode and high-NA objective lens. Under the conditions of the disk diameter of 120 mm, cover layer thickness of 0.1 mm, track pitch of 0.32 µm and data bit length of 0.104 µm/bit, a low bit error rate (ber) of 10-5 was obtained in both modulations of D8-15 and RLL(1,7) with partial response maximum likelihood (PRML). A wide tilt margin comparable to that in the case of DVD-RAM was obtained in RLL(1,7).

New Prml for Asymmetrical Signals in High-Density Optical Disks

The partial response maximum-likelihood (PRML) signal processing technique is effective for high-density recording media. However, asymmetry in the playback signal, which is caused not only by inter-symbol interference, but also by mismatched recording power in phase-change optical disks, markedly degrades the quality of PRML signal processing. In this paper, we propose an adaptive equalizer with a LMS algorithm for asymmetrical signals. We show the improved results in recording and playback experiments.

High-density recording on a dual-layer phase change disk using partial response maximum likelihood method

The possibility of obtaining 50 GB capacity/side has been studied using a blue laser diode, a high-NA objective lens and a dual-layer phase change disk. Using the partial response maximum likelihood method (PRML), which is a superior method of decreasing bit errors at a high linear density, we have obtained a low bit error rate less than 3×10-5, wide radial and tangential tilt margins, and wide power margins in both recording layers of a dual-layer disk.