Michael Nadeau
Optical phase change has promised the most as a rewritable medium, but high hardware and medium costs have kept it out of the mainstream. Matsushita hopes to change that. At Comdex, its Panasonic Communications and Systems Co. (Secaucus, NJ) showed a hybrid quad-speed CD-ROM reader/phase-change read-write device that it refers to as PD (phase-change dual). The half-height drive uses the same laser mechanism to read CD-ROMs and to read and write phase-change cartridges. The one-sided phase-change discs can hold up to 650 MB of uncompressed data, and a PD drive delivers a claimed average read rate for the phase-change disc of 870 Kbps.
The laser mechanism is surprisingly simple for a hybrid device (see the fig
ure), especially when you consider the differences between phase-change and CD-ROM media. Tracks on a CD-ROM, for example, are arranged in a spiral. Phase change, on the other hand, uses the same concentric track arrangement as your hard drive.
The Matsushita device automatically senses which type of medium is in the unit and handles it accordingly. The loading mechanism had to be redesigned, because the phase-change medium is enclosed and the CD-ROM medium is not.
According to Rich Harada, Panasonic's national marketing manager for optical drive products, the most difficult part of the design process was to develop a more sensitive phase-change medium that was also cheaper. This allowed the use of a smaller, less powerful laser.However, the new medium is incompatible with all other current phase-change drives.
Panasonic expects a complete PD drive kit to retail for less than $1000 and appear sometime this quarter. Plasmon Data, which collaborated with Matsushita on developing the medium,
says the price for the medium could go under $50 per disc in quantity. Plasmon has already announced a commercial PD drive that's called the PD2000e. NEC Technologies has said it will use PD drives in a line of multimedia PCs to be sold in Japan. Harada says that several U.S. manufacturers will make similar announcements early this year.
Will PD fly? Its pricing is attractive for a removable high-capacity storage device. The phase-change medium is faster and more durable than tape and much cheaper than removable hard drives. Both Panasonic and Plasmon say they will first target traditional users of removable storage, in areas such as prepress and imaging.
Bob Katzive, an analyst with Disk/Trend (Mountain View, CA), thinks PD may succeed in the mass market. ``The optical industry in the past, except for CD-ROM, has shown the ability to shoot itself in the foot. [PD] may be the way to break out of this pattern.''
The PD laser mechanism
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The PD laser mechanism is similar to that of a standard CD-ROM drive. A key difference is the use of a polarized hologram, which improves the efficiency of the laser while reading phase-change discs.
Significant Enterprise Data-Storage-Device Developments
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Rewritable Drive Integrates Two Optical Technologies
