TOKYO Three Japanese companies have proposed a compact magneto-optical disk format for digital still camera storage in hopes of breaking new ground for the the disk-format system in Japan, where it faces pressure from disk formats such as writable CDs and Zip disks.
Olympus Optical Co. Ltd., Sanyo Electric Co. Ltd. and Hitachi Maxell Ltd. have jointly developed a 50-mm-diameter, 730-Mbyte MO disk system dubbed the iD (intelligent, image disk) format. They have proposed that the new format be used as the next-generation storage medium for digital still cameras.
The 50-mm MO disk system is based on the 6-Gbyte Advanced Storage Magneto Optical (AS-MO) disk format, which has the largest capacity among the already announced 12-cm-diameter rewritable media, including DVD-RAM.
AS-MO is based on Magnetically Induced Super Resolution (MSR) technology. Generally, a laser beam cuts marks smaller than the beam spot by making use of the difference in temperature in the spot on the disk surface. But readout resolution is limited to the beam-spot size. MSR technology enables the disk system to read data spots smaller than a laser beam spot size by masking adjacent spots using both the laser beam and a magnetic field.
The disk has two layers for an MSR disk system a recording layer and a layer that functions as a mask for reading out. With Central Aperture Detection MSR, which is used for AS-MO, a laser beam heats a spot on a disk, and the magnetization at the center of the spot with the highest temperature is transcribed to the magnetic layer. This transcribed magnetization is then read out as 1 bit. It works like a window that allows the extraction of only 1 bit of the recording layer.
The AS-MO disk specification was published in April 1998 by the Advanced Storage Technical Conference (ASTC), which consists of 15 companies. Founding members were Fujitsu Ltd., Hitachi Ltd., Hitachi Maxell, Imation Corp., Olympus Optical, Philips Electronics N.V., Sanyo, Sharp Corp. and Sony Corp. No company has started selling AS-MO systems yet.
The 50-mm iD disk has about one-eighth the disk space of the 12-cm AS-MO disk. "The 50-mm diameter is a trade-off between the capacity and compactness. We wanted to have at least the capacity of CDs," said Kenji Torasawa, general manager of the Sanyo Hyper Media Research Center, which claims to have made significant contributions to the development of AS-MO.
The three iD promoters worked to optimize the AS-MO disk for digital still cameras. The iD disk, for example, uses more sensitive material to react to a low-power laser and magnetic head.
"We developed the iD disk for the digital still camera. Consideration of low power consumption was very important," Torasawa said.
Sanyo recently announced it has adopted IBM's microdrive for a new digital still camera. Sanyo, a major supplier of digital still cameras to other OEMs, is pursuing a digital camera that can shoot both moving and still images. For this purpose, the company has been looking toward larger-capacity storage.
For now, IBM's microdrive is the practical solution, said Sanyo when it announced the new camera in June. But the drive costs 58,000 yen (about $480) in Japan, which is too expensive to be used as a removable medium. So most users have to move image data from the microdrive to some other storage medium. "Images in iD disks can be stored as is without moving data because the iD disk is an inexpensive MO disk," said a Sanyo spokesman.
Olympus expects that "the iD disk system will bring new applications that a conventional digital still camera could not offer," said a company spokesman. He listed applications such as digital albums and the creation of high-quality picture archives that include audio. He noted, however, that iD disks do not aim to replace all the flash cards currently used for digital still cameras.
Olympus and Sanyo both plan to introduce digital still cameras with iD drives by next summer.
Though the iD format is based on the AS-MO format, not all members of the ASTC camp support iD. But iD proponents said they are inviting more companies to join their group. Camera manufacturers Konica, Kyocera, Minolta, Nikon and Ricoh said they support the format.
Sanyo and Hitachi Maxell are also joint-development partners of MAMMOS (Magnetic Amplifying Magneto-Optical System) technology, which enables the doubling of MO-disk recording capacity.
The iD format proponents expect that with the use of a blue laser, capacity can be expanded about fivefold to 3.6 to 3.7 Gbytes in the future.