Random seed scrambling method for high density phase change optical discs

Repeatedly rewriting the same channel bit pattern at the same location on a phase-change optical disc usually causes the media to deteriorate. To prevent this, the random bit shift of 128-bit and the free polarity of NRZI-converted pulses were introduced into the DVD-RAM system. However, these measures cause difficulty in the timing control at writing starts and. complication of the control of circuits. So in this paper, a new scrambling method, the Random Seed Scrambling Method is proposed. In this method, the data is scrambled using a different seed each time the data is written, so the different data is over-written at the location each time. The method of random seed scrambling has a unique characteristic that the seed is not necessary to de-scramble the scrambled data. By using this method, the amount of the high density phase-change optical disc wear is reduced.