If phone calls and web pages can be beamed through the air to portable devices, then why not electrical power, too It is a question many consumers and device manufacturers have been asking themselves for some time. But to seasoned observers of the electronics industry, the promise of wireless recharging sounds depressingly familiar. In 2004 Splashpower, a British technology firm, was citing “very p” interest from consumer-electronics firms for its wireless charging pad. Based on the principle of electromagnetic induction (EMI) that Faraday had discovered in the 19th century, the company’s “Splashpad” contained a coil that generated a magnetic field when a current flowed through it. When a mobile device containing a corresponding coil was brought near the pad, the process was reversed as the magnetic field generated a current in the second coil, charging the device’ s battery without the use of wires. Unfortunately, although Faraday’s principles of electromagnetic induction have stood the test of time, Splashpower has not — it was declared bankrupt last year without having launched a single product.
Thanks to its simplicity .and measurability, electromagnetic induction is still the technology of choice among many of the remaining companies in the wireless-charging arena. But, as Splashpower found, turning the theory into profitable practice is not straightforward. But lately there have been some promising developments.
The first is the formation in December 2008 of the Wireless Power Consortium, a body dedicated to establishing a common standard for inductive wireless charging, and thus promoting its adoption. The new consortium’s members include big consumer-electronics firms, such as Philips and Sanyo, as well as Texas Instruments, a chipmaker.
Fierce competition between manufacturers of mobile devices is also accelerating the introduction of wireless charging. The star of this year’s Consumer Electronics Show held in Las Vegas was the Pre, a smart-phone from Palm. The Pre has an optional charging pad, called the Touchstone, which uses electromagnetic induction to charge the device wirelessly.
As wireless-charging equipment based on electromagnetic induction heads towards the market, a number of alternative technologies are also being developed. PowerBeam, a start-up based in Silicon Valley, uses lasers to beam power from one place to another.
It now seems to be a matter of when, rather than if, wireless charging enters the mainstream. And if those in the field do find themselves languishing in the disillusionment, they could take some encouragement from Faraday himself. He observed that “nothing is too wonderful to be true if it be consistent with the laws of nature.” Not even a wirelessly rechargeable iPhone.
What’s the difference between the technology of Splashpower and that of PowerBeam（）
A.Splashpower lies on the principle of EMI and PowerBeam doesn’t
B. Splashpower uses coils to cause EMI and PowerBeam uses lasers
C.Splashpower went bankrupt and PowerBeam grows prosperous
D. PowerBeam uses a special charging pad and Splashpower doesn’t