Magneto-optical drive targeted at DVD-RAM applications..........
eet.com
Fujitsu, Sony partner on 1.3-Gbyte MO
drive technology
By Yoshiko Hara
EE Times
(11/06/98, 2:10 p.m. EDT)
TOKYO — Fujitsu Ltd. and Sony Corp. have jointly developed a
3.5-inch magneto-optical (MO) disk system that implements
magnetically induced super-resolution technology to obtain a capacity
of 1.3 Gbytes. That's the largest ever achieved for a 3.5-inch drive, the
partners said.
Lifting the capacity to gigabyte level and increasing the data-transfer
rate by about 25 percent, to 5.92 Mbytes/second, the two companies
intend to qualify the MO system as multimedia-ready data storage for
PCs.
Named Gigamo, the system stays with a conventional optical head to
provide read and write compatibility with preceding generations at
128, 230, 540 and 640 Mbytes. But the capacity is twice that of the
640-Mbyte MO generation.
"There are various rewritable formats, but MO is the best suited for
PC-storage applications," said Takeshi Maruyama, executive senior
vice president of Fujitsu.
Indeed, "MO is now widely accepted, especially in Japan," said
Hiroshi Makino, vice president of Sony's Recording Media & Energy
Co. "About 28.2 million MO disks are expected to ship this year, and
the volume is the evidence of the wide acceptance."
Fujitsu plans to ship the Gigamo drive next spring and Sony will
provide the MO disk simultaneously. Sony's collaboration, however, is
limited to disks and will not extend to the hardware.
About 1 million units of MO drives were sold in Japan and about half a
million units were sold outside of Japan last year, according to Koich
Ogawa, general manager in charge of optical business at Fujitsu's
Storage Product Division. This year's projection is 1.4 million units in
Japan and 0.6 million overseas.
"In Japan, the MO systems have penetrated and now we can offer
Atapi [AT Attachment Packet Interface] type drives, targeting the PC
built-in market," said Ogawa. "But the U.S. market is heavily price
oriented and, frankly speaking, it is difficult to draw the future of MO
there." Ogawa suggested the company was considering a U.S.
introduction for Gigamo, but has not yet drawn up full plans.
The key to Gigamo's capacity is magnetically induced super-resolution
(MSR) technology. In an MO system, the laser beam can cut marks
that are smaller than the beam spot by making use of the difference in
the temperature of the disk surface in that spot. But readout resolution
is limited by the beam's spot size. The diameter is about 0.6 micron for
MO drives, including Gigamo. MSR technology makes it possible to
read out a bit that's smaller than the beam spot by masking the
adjacent bit that would otherwise be in the way.
MSR is based on Sony's high-resolution technology called Irister (IRIS
Thermal Eclipse Reading), developed in 1991. Fujitsu's
double-masking technology was combined with Irister to resolve
precise control issues of magnetic-field intensity, a bottleneck for
practical application.
Gigamo has the same cartridge size, disk diameter and disk thickness
as existing MO systems standardized by the International Standards
Organization. But to realize the doubled capacity, track pitch was
narrowed to 0.9 micron (from 1.1 microns), the minimum mark length
to 0.38 micron (instead of 0.64) and bit length to 0.29 micron (rather
than 0.49).
Recording starts from the outer track to increase transfer rate. In
conventional MO it begins at the inner track.
"Their real target may be to beat DVD-RAM before its takeoff," said
Hiroshi Motohashi, president of Trend Concept, a market-research
company specializing in peripherals. "Fujitsu has only MO as a
large-capacity storage drive, and Sony's DVD+RW is behind
schedule."
Gigamo is supported by MO drive venders Olympus and Konica, and
by media venders Hitachi-Maxell, Kyocera, Mitsubishi Chemical,
Philips/PDO Teijin and Toso. |
