Toshiba Focuses on Mobile Devices
Toshiba Corp of Japan is now placing keen development emphasis on mobile devices and audio-visual (AV) equipment. "We're going to ship products this year --lots of products," said Tetsuya Mizoguchi, president and CEO of Toshiba Corp's Mobile Communications Company.
Methanol Design
In the area of fuel cells for mobile devices, Toshiba demonstrated its "GENIO e" personal digital assistant (PDA) (see Fig). This was the first time that the firm had shown its prototype in operation. Similar fuel cells are also under development at NEC Corp and Hitachi Ltd, both of Japan, but there are few reports of any designs offering an output capable of driving a PDA for a specific period of time. Toshiba's Mizoguchi believes that "2005 is too late" for commercialization, and plans to ship as soon as possible.
The prototype fuel cell is a direct methanol design, where the fuel electrode is directly immersed in a methanol/water fuel mixture. A 10ml fill of methanol generates electricity for two to three hours. Output is about 4V, but an internal voltage booster is used to boost fuel cell voltage of 2V.
Power density is high, at 30mW/cm2, and the cell is capable of supplying a constant average power of 5W. The power density is increased by using a pump to disperse the methanol/water fuel mixture onto the electrode while spraying.
The device has a tank for a 98% concentration of methanol, and a separate water tank. A solution of 3-5% methanol is created internally and pumped to the fuel electrode. A resin board with fluid channels on the surface is used to ensure uniform dispersal of the fuel mixture over the entire electrode.
The electrode material uses a proprietary catalyst developed by Toshiba. Normally these catalysts are Pt-based with Ru, but Toshiba has modified both the component ratios and additional new materials.
The fuel cell is capable of outputting a constant current for a long period of time, but is ill-suited to quickly producing the large currents needed to start up personal computers (PC), for example. This is why the PDA internal Li-polymer rechargeable batteries are used to start up the PDA. As one development engineer said, "When we actually commercialize this, we'll have to add some sort of auxiliary power source, maybe a double-layer capacitor."
Perpendicular Recording
A hard disk drive (HDD) using perpendicular magnetic recording has been prototyped for use in notebook PCs, and was demonstrated for the first time in a commercial PC. The HDD areal recording density is 35 Gbits/inch2. The drive has a single 2.5-inch platter and two heads, with a capacity of 20 Gbytes.
Toshiba has already prototyped a model with an areal recording density of 52 Gbits/inch2, also with one platter and two heads, for a capacity of 30 Gbytes. Both designs use single recording heads with high saturation-magnetic flux density, and giant magnetoresistive (GMR) heads for playback. The media is a two-recording layer design made for perpendicular recording, with playback voltage said to be double that of the conventional longitudinal recording scheme.
Information about product specifications and expected shipping dates has not been released, but according to a source in development, "We are now evaluating reliability under various temperature and magnetic field conditions. Evaluations are being made of the assembled HDD, not of individual components."
When the limits of longitudinal magnetic recording are reached to areal recording density of 100 Gbits/inch2, the firm will commercialize the new drives. If the pace of increase in areal recording density remains as it is, this means some time in 2003.
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