That technology was Microsoft's Wrist.NET line of watches. These watches were only slightly larger than normal (although my special-edition Dick Tracy model stuck out obviously and made for fascinating conversations) and were capable of checking email, receiving IMs, checking the news, weather, sports, and stock reports, giving local movie times, and a laundry list of other life-related tasks. They could even tell time. In typical Microsoft fashion, the watches were actually built by third-party manufacturers such as Fossil and Suunto. All of them were more-or-less equals, but Fossils' stood out from the crowd (in my mind) for one key feature: the watches could be charged without wires.This was not only handy - they had the battery life of an average cell phone - but just downright COOL in my book. It seemed magical that somehow electricity was being transfered from one place to another, and the only parts touching were made of PLASTIC.
Well, I'm older now and we've come a long way in the last 6 years. Wireless charging is now finally becoming more common, and while many people are still completely unaware of the technology, multi-purpose wireless charging pads are for sale at pretty much all major stores these days for a fairly reasonable price. Also, the vast majority of modern battery-powered toothbrushes are charged wirelessly.There's still a looming question, though: How does it work?!
The answer is "Magnetic induction."
The principles of magnetic induction are actually quite simple and have been known for decades. Think back to high-school physics for a moment. One of the experiments every student does at some point in their education involves magnets and electricity (or simply "electromagnetism"). The basics of the experiment are that if you pass a magnet back-and-forth through a coiled wire, electricity is generated in the wire. This happens because as the magnetic field passes through the coiled wire, it excites the electrons in the metal and they move accordingly.
The reason that this experiment is always done with copper wire is copper has a very high conductivity. High conductivity means that electrons can easily and freely pass though a material, which in turn means that more electricity can pass through the wire and more can be generated by the magnetic field.
The opposite of all of this is also true. If electricity is run through a coil of wire, the wire will generate a magnetic field.
So, when one coil of wire is fed electricity and another identical coil of wire is very near and oriented in the same direction, both effects happen at once. The electricity in the first coil (which would be the coil of wire inside of the charger) generates a magnetic field. This magnetic field meets with another coil of wire (the one attached to the battery in whatever's being charged) and the invisible action of the pulsating magnetic field from the first coil generates an electric charge in the second coil, thus charging the battery without any wires in between the two.
 |
| Depiction of both concepts used separately (a and b), then in tandem (c). |
This all happens not only without wires, but silently, invisibly, and rapidly. In fact, the only way to verify that the watch or toothbrush or cell phone is "plugged in" is to check and see if the charging light has turned on. It's a good thing those lights exist, too, or we'd otherwise be completely ignorant of anything happening whatsoever.
=========================
Magnetic induction is actually only one form of wireless charging, but it is the most commonly used. It operates at low frequencies and low voltages and only works over extremely short distances, but is also much cheaper, more practical, and easier to manufacture than other methods currently available. Fujitsu announced just today that they have developed a new form of wireless energy transfer using magnetic resonance. It will allow users to simply be within a few meters of a charging station (in any direction) for their devices to begin automatically charging. This particular technology is slated for a 2012 release.
========================================
No comments:
Post a Comment