Pioneer Corp. and TDK Corp. have jointly developed a write-once read-many-times optical disc, with the hopes that the technology will be included in the "Blu-Ray Disc" specification.

In the development of the Blu-ray Disc specification, only the specification of the rewritable single-sided single-layer disc has been virtually completed. The specification for the single-sided double-layer rewritable madia, read-only media and write-once media has yet to be completed. Pioneer and TDK plan to propose that their new technology be incorporated in the Blu-ray Disc specification for the write-once media.

The prototype disc has a recording capacity of 23.3GB and 25GB in a single layer on one side. Its maximum data transmission speed is 72Mbps, which is twice as fast as the standard data transmission speed of 36Mbps.

The results of the tests using prototype recording/playback equipment showed that the disc's quality is sufficient for commercial use. According to the companies, TDK has confirmed in its laboratory that the disc enables a maximum transmission speed of 140Mbps, which is about four times faster than the standard speed.

The two companies have yet to reveal details of the recording film, except that it is metallic and that the recording power on the disc is between 4.5mW and 6mW. The disc's tracking method, track pitch and recording bit length comply with the existing Blu-ray Disc specification, the companies said.