Chikashi Inokuchi

Compatability test for phase-change erasable and WORM media in a multifunction drive

We have presented configuration of the multifunction drive, interchangeability test, and reliability test consisting of temperature test and reading many cycles test. The multifunction drive could be realized by adding laser power control block and the polarity switch of reading amplifier without changing the WORMs head on a current WORM drive. Interchangeability test results showed having good interchangeability among multifunction drives or among WORM drives, and also the multifunction drive had full compatibility with current WORM drive on the current WORM disk. Reliability test results for the multifunction drive using a PCE disk and a WORM disk showed that writing sensitivities of both disks were much less dependent ont he temperature and the drive had stable writing characteristics in environments from 5 degree(s)C to 50 degree(s)C, and furthermore no error bit was observed while reading the most inner track of each disk 10 million cycles with the read power of 1.8 mW being 20% up to normal one at 6.1 m/s of disk velocity.

Recording laser power control method based on wobble signal amplitude detection

The DVD-RAM, now a world standard among rewritable high-capacity optical disks, is expected to have wide applications in the PC and AV fields. However, when a recording and reproducing optical disk’s surface is soiled with fingerprints or dust, generally some writing error can be happened. As a solution to this problem, this paper presents the method for controlling recording laser power to improve recording reliability.