Writing Power Optimization Method for Rewritable Optical Media

For rewritable optical media, overwriting repeatability is a very important index of performance. In HD DVD-re-recordable (RW) media, the direct overwrite (DOW) margin becomes narrower than that in conventional rewritable media, because the recording density becomes high. Therefore, it is difficult to obtain sufficient DOW characteristics by conventional writing power control methods. In this study, we investigate the degradation factor of DOW characteristics in HD DVD-RW media and develop a new writing power optimization method, which involves detection of changes in space level alter DOW. As a result of optimizing writing power of HD DVD-RW media by this new method, the partial response signal-to-noise ratio (PRSNR) after 1000 DOW cycles is about 24 in commercial drives, and it is much more improved than that obtained by conventional methods. Accordingly, it is possible to realize optical disk drives with high recording performance for rewritable optical media.