IMPROVED HIGH-DENSITY PHASE-CHANGE RECORDING

By using a simple write strategy we have found that a wide range of li near velocities can be covered for direct overwrite in high-density ph ase-change recording. This is especially advantageous for data recordi ng where the application of constant angular velocity facilitates fast seek and short random-access times. In the case of repeated overwriti ng, material flow will limit the number of cycles, particularly if a f ixed pseudo-random data pattern is used: We studied how a random bit s hift can reduce this problem and found that a relatively large shift o f up to 100 bytes was required. Using these techniques in an optimized disc structure we achieved more than 100,000 overwrite cycles on a 2. 6 Gbyte 12 cm phase-change disc.