A Japanese university has shown a prototype 1-inch hard drive that packs data on the disk surface more densely than existing hard drives.

The density with which information can be packed onto the disk is particularly important in the tiny hard drives used in handheld electronic devices such as digital music players.

The prototype 10GB drive packs data with an areal density - the number of bits per unit of disk surface area - of 138Gb per square inch, said Yoshihisa Nakamura, who heads the project at Tohoku University's Research Institute of Electrical Communications. His laboratory developed the prototype drive as part of a project to increase the storage capacity of handheld electronics devices.

The Perpendicular promise

The prototype drive uses perpendicular recording technology to achieve its higher areal density, Nakamura said. The technology works by standing the magnetic fields that represent data bits upright. In commercially available drives, those fields lay flat on the surface of the disk. Standing these fields upright means they take up less space, enabling more data to be crammed on the disk.

Many hard drive manufacturers are experimenting with perpendicular technologies. Seagate has already revealed such devices, which it says could form the foundation for very high capacity portable drives in future.

"For one-inch [drives], 138Gbit areal density is a world record. Somebody may have a higher density in a lab somewhere, but they haven't shown them," Nakamura said.

Japan's Hitachi Global Storage Technologies (HGST), Fujitsu and Toshiba worked with Nakamura to develop the prototype, he said.

HGST is considering commercializing the drive, although the company has not said when, he said.

30GB iPod minis will be possible

Nakamura said his lab should be able to boost the areal density of 1-inch disks to about 500Gbits per square inch in 2007. This could enable 1-inch drives to have capacities as high as 30GB a few years from now, he said. Currently, the highest-capacity 1-inch drives on sale store a maximum of 6GB of data.