Sharp, Sony Develop Disc for Portable Devices

TOKYO (03/23/2000) - Sharp Corp. and Sony Corp. today said they have developed a small, high-density magneto-optical (MO) disc for use in portable multimedia terminals.

The new system, which is based on a 50.8 millimeter disc, won't help terminal makers reduce the size of their units or save battery life -- both usually key concerns when designing new systems for use in mobile applications. If anything, the system will lead to a reduction in battery life and a larger product than those based on memory card systems -- but the new disc delivers one big advantage: a very large storage capacity.

A version based on a conventional red laser can store up to 1G byte of information, and engineers are already working on applying a shorter-wavelength blue laser, which will allow the capacity to be pushed up to 2G bytes per disc.

In contrast, much larger compact discs can hold 650M bytes of data and the first generation of DVD-ROM discs can hold 2.6G bytes. The largest of today's memory cards holds 64M bytes of memory, and 1G byte cards are expected to be more than a year away from commercialization.

The system is based on the MO removable media format that is commonly used in Japan and its reliability, which is superior to that of optical disc systems like CD-RW and DVD-RW, is why the companies chose it as a base for the new system, said Sony spokeswoman Aki Shimazu. To further increase reliability, the disc will be enclosed within a cartridge to make the entire media 54 square millimeters and 4 millimeters thick.

The two companies say support for the format, vital if it is to enter into widespread use, has already been pledged by a host of electronics companies including Casio Computer Co. Ltd., Fujitsu Ltd., IBM Japan Ltd., Mitsubishi Chemical Corp., Pioneer Corp., Royal Philips Electronics and TDK Corp.

Together they will promote the format and begin work on a future generation disc which utilizes a blue laser and a 65 millimeter-diameter disc to provide data storage capacity of 4G bytes.

The system is still under development and the spokeswoman declined to speculate on when it might be launched commercially.

Sharp Corp., in Tokyo, can be found online at and Sony Corp., also in Tokyo, can be found online at

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