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Fujitsu Eyes Wireless Gadget Charging For 2012 158

Posted by timothy
from the don't-cross-the-streams dept.
angry tapir writes "Researchers at Fujitsu Laboratories have developed a wireless charging system that they say can simultaneously charge a variety of portable gadgets over a distance of several centimeters without the need for cables. The system, which will be detailed at a technical conference in Japan this week, could begin appearing in mobile phones and other products as soon as 2012, the company said. Fujitsu's system is based on magnetic resonance in which power can be wirelessly sent between two coils that are tuned to resonate at the same frequency."
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Fujitsu Eyes Wireless Gadget Charging For 2012

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  • Efficiency (Score:2, Insightful)

    by jaxxa (1580613)
    I believe the standard question is what is the efficiency?
    • Re:Efficiency (Score:5, Informative)

      by Anonymous Coward on Monday September 13, 2010 @01:11AM (#33558562)

      You could read the article. The efficiency is 85% at 15cm, and much higher at closer distances, since the efficiency drops off with the cube of the distance.

      • by Sycraft-fu (314770) on Monday September 13, 2010 @02:24AM (#33558828)

        Funny, since the concern not long ago was making wall warts more efficient (switching ones did a good job on that) and working on reducing "leaky" devices like TVs and monitors that don't turn fully off (my NEC has a hard off switch for that reason). But now we can lose any and all those gains with an inefficient transfer system.

        Yay.

        They'll have to forgive me if I wish to stick with my nice, efficient, wired connections.

        • by Twinbee (767046)

          It won't cost that much more, especially with 85% efficiency @ 15cm.

          I'm prepared to go down to as much as 10% efficiency or maybe worse so that I can sit at the other side of the room if I want to.

          And TV standbys if done properly probably cost around 5p per year. Not a fortune.

          • by Deluge (94014)

            "And TV standbys if done properly probably cost around 5p per year. Not a fortune."

            Right. The problem is the hundreds of millions of these leaky devices combining to drain a significant amount of power, not your personal cost of 5p.

            • by Twinbee (767046) on Monday September 13, 2010 @06:29AM (#33559648) Homepage

              Okay, we'll sort out that out after the 456,917,831 other things which waste more time/energy/money. The top 100 are several orders of magnitude more important than this.

              It's really a drop in the ocean. It's the equivalent of spending 5 minutes trying to cut open a can of shaving cream to get the last little bit.

              I used to go a little OTT on saving paper, or closing the fridge door ASAP, until I realised that the ink is orders of magnitude more expensive, and that the worry (no matter how little) of keeping the fridge closed is not worth the relatively small amount of money lost each year.

              We don't live forever. Let's make life more convenient whilst yes, picking the sensible low and/or middle hanging fruit for energy savers.

              • by GooberToo (74388)

                It's really a drop in the ocean.

                You need some help with math. A drop in the ocean times hundreds of millions of people times multiples per day is a lot of water. And that's exactly why so much energy is wasted. Energy prices would almost drop in half in the US if people with your math skills would pull their head from their tail.

                The amount of energy wasted on transformers left plugging into a wall is simply staggering and is the exact opposite of "a drop in the ocean." Now add to this an extra 5-15% waste when items actually are charging

                • Re: (Score:3, Insightful)

                  by Twinbee (767046)

                  I'm sorry, but 5p per year per household *is* miniscule - there's no denying that. 5p x population seems like a lot, but then you need to divide it by the population again to see that 5p per year really is just that - 5p. If there were a quadrillion people in the world, then we can make 5p x quadrillion sound like a stupid sum - that doesn't mean it counts. It's all proportional to the much bigger energy drainers.

                  Talking about such trivial energy wastage as though it's important is doing the damage in my op

          • by GooberToo (74388)

            It won't cost that much more, especially with 85% efficiency @ 15cm.

            That's likely the transmission efficiency. Add to that the transformer's efficiency. Likely, a realistic, fully encompassing number is something like 70% efficiency, if that.

            Why anyone would be excited about creating yet more power burden and demands, pointlessly, is beyond me.

        • Re: (Score:3, Interesting)

          by interkin3tic (1469267)

          Funny, since the concern not long ago was making wall warts more efficient (switching ones did a good job on that) and working on reducing "leaky" devices like TVs and monitors that don't turn fully off (my NEC has a hard off switch for that reason). But now we can lose any and all those gains with an inefficient transfer system.

          Why would you need your desktop computer or TV to have wireless power? I'd expect this would be useful mainly for mobile devices or things that for some reason or another need power but can't have a battery or wires. The "powerpad" that's out right now which is technically wireless is marketed as a convinient charging station for your cell phone, handheld gaming systems, camera ETC. With that, you have to set the thing right on top of the charging station, but 15 cm isn't that far either, it's probably n

          • by TheLink (130905)

            but 15 cm isn't that far either, it's probably not going to replace all cords anytime soon.

            There'd be a limit to distance (and power output), otherwise more people would be getting free power from their neighbours whether intentionally or not.

            And people would be complaining that the stuff is making them ill, filing lawsuits etc.

            • by c6gunner (950153)

              And people would be complaining that the stuff is making them ill, filing lawsuits etc.

              They'll do that, anyway. If you stop product development out of a fear that crazy people will sure you, you'll never develop anything.

          • by scdeimos (632778)

            GP didn't say that they wanted wireless-powered TV's and monitors.

            I believe GP was commenting on how much power is wasted in "standby mode" on such devices. For example, HDTV panels are often reported to consume less than 1-watt on standby but if you ask them to cache program info then parts of the system are active to monitor the DVB broadcast stream, often consuming 20-watts (or more).

            • Re: (Score:3, Insightful)

              by Sycraft-fu (314770)

              Also there's been a push, in the EU in particular, to have real, zero power draw off modes. I don't know that it is a big deal, but I see their point. A bit of draw might not be much, but when you have a lot of devices and it happens all the time, it adds up.

              I'm not sure that it is worth worrying a ton about, however in general efficiency makes sense when possible. Currently wired connections have as close to zero loss as you can get. There is a tiny bit of loss for the resistance of the wires and a bit of

              • It's a temporary problem anyway, born of our (again temporary) dependence upon power sources that are very expensive, and ultimately limited - petroleum, gas, etc. We will switch to practically unlimited sources of power - we have to - and as we do, the issue of vampire power will go away. Solar, with storage; nuclear; etc. Petroleum power is convenient because its easy, but given the other sources, it's also stupid, because petroleum is also a resource for things we can't replace.

                • by dave420 (699308)
                  No, it's just common sense. Waste is still waste, and is never a good thing.
                  • by mpeskett (1221084)

                    GP's point is that waste is only something to worry about when you also have scarcity.

                    Whilst there will always be some sort of finite limit to the power supply, electricity could be made so cheap to produce that it's not worth worrying about saving it, at which point waste becomes something of a non-issue.

                    It might still be "not a good thing", but it could become an acceptable evil if the cost of the waste really was minimal.

                    • by TheLink (130905)

                      GP's point is that waste is only something to worry about when you also have scarcity.

                      Waste can still be a problem if there is totally no scarcity, since waste heat will become an issue if everyone can use as much energy as they want. The Earth may even start glowing red/white hot (everyone would be having heat pumps etc, facing out to space) :). While you certainly could still live under such conditions (lots of energy to throw at the problem), it would be a rather ugly situation.

                      As for "standby waste" power, the "stand by" power draw of the modern "energy star" stuff is already tiny enough

                  • Waste is still waste, and is never a good thing.

                    Not true. Strictly speaking, heat is "wasted" energy. It has its uses.

                    Outside of mathematics, statements containing the word "never" are rarely true. ;)

                  • by fyngyrz (762201)

                    Waste is still waste, and is never a good thing.

                    Waste doesn't have to be a good thing. It only needs to become irrelevant. Then it's not a bad thing, either; the fact is, problems only arise when waste is a bad thing. Your assertion of "never" is incorrect.

                    If there is more than enough power for our needs, and there is no penalty for using more or less power, then we are in an altogether good place.

              • by Joce640k (829181)

                I want to know how much desk space my eight charging pads will take up (one for each device - you can bet they won't be compatible).

                Oh, wait, I see the point now! Once you have a SONY charging pad you'll prefer to buy another more SONY products because buying a competitor will mean you lose another six inches of desk space - it's the memory stick con in disguise!

                • by Stooshie (993666)
                  " ... I want to know how much desk space my eight charging pads will take up (one for each device - you can bet they won't be compatible). ... "

                  Erm, the summary says: " ... can simultaneously charge a variety of portable gadgets ... "
                  • by Joce640k (829181)

                    ...just not from any other manufacturer, hence the need for more.

                    (And probably not even a Fujitsu gadget two years from now - just you wait and see!)

                • by hitmark (640295)

                  Time for me to stand up in church and confess my heretical nature: "government regulation".

          • by Stooshie (993666)
            " ... Why would you need your desktop computer or TV to have wireless power? ... "

            Because I have a computer, a laptop, my wife's laptop, a tv, a sky box, a DVD player, a video player (Yes we do still have one) and a standard lamp all competing for socket space.
            • Because I have a computer, a laptop, my wife's laptop, a tv, a sky box, a DVD player, a video player (Yes we do still have one) and a standard lamp all competing for socket space.

              Are they all going to be within a 15 cm radius of each other? Because otherwise this wouldn't help, it's only 85% efficient at 15 cm and drops off from there, if they're going to be any further, this won't really help. Not to mention, I really doubt anyone is going to be making VCR players that can be powered wirelessly.

        • by Joce640k (829181)

          You sound poor.

      • by rossdee (243626)

        "The efficiency is 85% at 15cm, and much higher at closer distances, since the efficiency drops off with the cube of the distance."

        So at 7.5cm it would be (8 x 85%) = 680% efficient? Thats cool feed that energy back into the charger enough times and the worlds energy problems are solved...

    • Re: (Score:3, Interesting)

      by siddesu (698447)

      With "Fujitsu" as the maker, the standard question is "how much skin will they want from me".

      It will be small, efficient and maybe even work, but it won't be cheap enough to make sense to buy.

      At least the Japanese model.

      / Yes, I have a few Loox notebooks.

  • by jabithew (1340853) on Monday September 13, 2010 @01:20AM (#33558594)

    It would be nice if we could standardise this stuff. There are a few recharging matts* knocking around for sale at the moment, but all the systems are incompatible. Manufacturers won't build this into mobile phones etc. unless it's their own system or a standard.

    Just when we're finally converging around USB as a standard charger, it looks like we're going to have half a dozen wireless charging systems (one for Fujitsu, one for Apple...).

    *I do know that this isn't one of those, but it will still need infrastructure on the charged side.

    • by AHuxley (892839)
      Yes a portable gadget would be cool, anyone can charge with wires, no wires now.
    • by aXis100 (690904)

      at worst, a wireless adaptor that plugs into USB (could be embedded into a protective case) would work well enough.

      • by hitmark (640295)

        I have seen both cases and replacement batteries as variant solutions for older gear.

    • Re: (Score:3, Informative)

      by Aldanga (1757414)

      There definitely needs to be a set standard. I suspect IEEE or another such organization will eventually step up and figure out an agreeable standard.

      However, the technology hasn't advanced to the point where it's exactly realistic for most people, or even truly usable. Unless there is a significant breakthrough in the near future, such standardization will probably not happen anytime soon.

    • Re: (Score:3, Insightful)

      by Ihmhi (1206036)

      It would be nice if we could standardise this stuff.

      The hopes of that ever happening died the day a cell phone manufacturing executive realized how much money he could make with proprietary $30 chargers.

      • by Joce640k (829181)

        The replacement/extra batteries are even worse than the chargers.

        (I think the biannual "exploding battery turned out to be a Chinese fake!" stories are paid for by cell phone manufacturers...)

        • by Hadlock (143607)

          Paid for? Try "rigged and planted" by cell phone manufacturers. You'll note energizer, duracell and rayovac haven't jumped into the aftermarket cell phone battery ring....

    • by Joce640k (829181)

      This was announced *because* USB is becoming dangerously close to a standard for charging.

  • by TheNarrator (200498) on Monday September 13, 2010 @01:24AM (#33558614)

    Is it me, or are people having a hard time believing the technology actually exists?

    Two Companies Already Have Products:

    http://www.powercastco.com/ [powercastco.com]
    http://www.witricity.com/ [witricity.com]

    NY Times Covered this stuff in 2007

    http://www.nytimes.com/2007/12/09/magazine/09wirelessenergy.html?_r=1&ref=magazine [nytimes.com]

    Here's CNET demoing powercast's tech in 2007!
    http://cnettv.cnet.com/powercast/9742-1_53-25606.html [cnet.com]

    You can buy full blown evaluation boards online that powercast manufactures that implement wireless electricity:

    http://www.futureelectronics.com/en/technologies/development-tools/rf-wireless/Pages/9660812-P1110-EVB.aspx [futureelectronics.com]

    Why is everyone having such a hard time with this concept?

    • by OBeardedOne (700849) on Monday September 13, 2010 @01:57AM (#33558738) Homepage

      I thought wireless power looked fantastic until I took a closer look at what you are actually getting. You can't just chuck your phone on the wireless charger pad and have it magically charge the phone. You need to either add a special "sleave" to the product you want to charge wirelessly or actually plug the product into the charge pad using various adapters which completely negates any real benefit from "wireless" power.

      So for gadgets that currently are not "wireless power" enabled the tech kinda sucks and it is being overhyped in a major way - at least based on the product packaging and in-store displays that I've seen. It will be interesting to see if it takes off when manufacturers find a way to seamlessly incorporate this into new devices

      • by OBeardedOne (700849) on Monday September 13, 2010 @02:31AM (#33558842) Homepage

        As a follow on to my earlier post, this is the clincher for the tech - from the article:

        "Fujitsu's system couples a coil with a capacitor in receiving devices. The size of the device determines the size of coil it can accommodate and that in turn affects the capacitance."

        So the bigger the coil in the receiving device the better. That aint going to go down so well for mobile phones, ipods etc where the size of the battery/power supply is absolutely crucial to the success of the product i.e. smaller is better. If it doesn't make sense for the mobile market then it won't be anything more than a niche product for the foreseeable future. Particularly when the benefit hardly comes close to outweighing the cost - really, how hard is it to plug a phone in?

        • I would agree with you, but then again I've lost the charging cable for several phones in the past. When companies refuse to standardise their connections (MicroUSB on all mobile phones please. Support charging by USB. That is all.) you get stuck with a very pretty paperweight, or the cost of a proprietary cable.

          Now, I only buy phones with MicroUSB connections. If I didn't need to worry about that for charging (this wireless charging tech), then I wouldn't need a cable at all. I can connect over Wireless L
        • by Joce640k (829181)

          really, how hard is it to plug a phone in?

          Much too hard, apparently - read the comments.

          • by Stooshie (993666)
            Plugging it in is easy. That is not the benefit of this device, however. It's the "wireless" bit that is the benefit.

            Have you looked behind your TV unit or computer desk recently?
        • by Stooshie (993666)
          The bigger the coil refers to the number of loops, not actually the physical size (although there is a relationship, obviously).

          If it was possible to make the wires thinner, that would work.
        • by Shotgun (30919)

          So the bigger the coil in the receiving device the better. That aint going to go down so well for mobile phones, ipods etc where the size of the battery/power supply is absolutely crucial to the success of the product i.e. smaller is better.

          The wires of the coil only need to carry micro-amps, and can therefore be extremely thin. I could see the coil being made of stainless steel and being cast into the case of the device. The case would be reinforced slightly by the coil, and it would add less weight than providing for the current external connector.

      • The power is not transmitted via an electric toothbrush type induction coil. It's transmitted through magnetic resonance which is an entirely different physical process that lets the transmission work when the charger and the device to be charged are not touching.

        Watch the CNET video I linked to above and notice how utterly mystified the presenter is that the Christmas tree light branch lights are lit up and the device has no embedded power source and is not physically touching or adjacent to the power sou

        • Re: (Score:3, Interesting)

          > magnetic resonance which is an entirely different physical process

          Hmmm. You're going to have to explain to me, a physicist, exactly what you think the difference between magnetic induction and magnetic resonance is, aside from the name. I'm all ears.

          • by GaryOlson (737642)
            Magnetic induction you induce the electrons to a higher energy state with voltage coupons and customer rewards points. Magnetic resonance the charging device creates a catchy phrase which it repeats with high frequency across many mediums till the mobile device can't help but resonant the catch phrase subconsciously thus increasing its energy state. That's what the marketing dept tells me....
          • Re: (Score:3, Informative)

            by Muad'Dave (255648)

            I modded you up, then thought about it for a sec. I think they're talking about using evanescent waves [wikipedia.org] instead of classical mutual inductance. Evanescent waves separate the near field and far field [wikipedia.org] when modeling antennas, btw.

            Here's an article [witricpower.com] that's heavy on buzzwords but may explain it.

    • by Mike McTernan (260224) on Monday September 13, 2010 @02:20AM (#33558814) Homepage

      Splashpower started in 2001: http://en.wikipedia.org/wiki/Splashpower [wikipedia.org]

      I actually saw one of their demonstrations and it was cool. The pad was just a slightly thick mousepad like device, and you could put multiple phones of different types on it at the same time and at any orientation. They had modified battery modules to contain their own chip which did the inductive pick up and regulation. They said their goal was to get the chip built into devices by default, although unless the chip was very cheap, I suspect this would have been difficult to include in cost sensitive mobile phones and iPods.

    • Why is everyone having such a hard time with this concept?

      IDK, especially since I already have one in my home. It's a flat "pad" that plugs into the wall. You lay a Wii controller on the pad, and it charges the controller without plugging it in to anything. Sounds like this is the same technology referenced in the article.

  • by dbIII (701233) on Monday September 13, 2010 @02:02AM (#33558760)
    I'm hoping that charging everthing from USB beats it to the punch. There are already piles of cheap car apaptors, wall warts, solar etc in addition to PCs and powered hubs. One octopus-like charger with leads going in all directions beats a long power strip with a lot of wide transformer plugs. About the only downside is slow charging speeds due to low current, but a lot of the time that doesn't matter.
    Building half a transformer into all of these gadgets adds weight, cost and complexity in addition to the power transfer being lossy.
    • by Sycraft-fu (314770) on Monday September 13, 2010 @02:19AM (#33558808)

      A lot of devices use USB charging already so a lot of people have a charger (or more than one). It also has the advantage that any computer is a charger by default, so even if you don't have a dedicated charging unit, you can still charge your device. I charge my phone off my laptop when I travel, so I only have to bring the laptop's cord. Also, USB is a nice, standard data interface. Means that in the event the device needs data, you don't need another port.

      My smartphone, my Logitech remote, our camera at work, and so on all charge from, and communicate by, USB and it is really nice.

      To me, wireless charging seems stupid since it is extremely range limited. You can't have wireless charging as in "I have a charger in my kitchen and devices everywhere in the house charge." The pesky inverse square law bites that in the ass. It is something where they have to be close to touching. Ok well that just means instead of plugging in your device, you instead plug in a charger, and then set your device on it. Oh yay, that is so much better... Or not.

      We just have to accept the fact that wires are here to stay for many things, power being the biggest one. You can't effectively convey power over anything other than an extremely short distance without a wire. Makes all wireless charging very silly if you asked me.

      I mean think about it in relation to data. The reason I have a wireless AP is because that one AP lets me use my laptop anywhere in my house. I can roam around and get data at the same rate no matter what. That makes it worth having. However say rather than that, it was a little unit that had to connect to wired Ethernet and your laptop had to sit right next to it to get data. You could move an inch or two at most before losing signal. Would you bother? I wouldn't, I'd just connect the wire directly. It wouldn't save me any hassle to have to set the laptop right next to something connected to a wire over just connecting the wire itself.

      • For me, wired connection is not really that great.

        If you plug in/unplug device daily (charging smartphone), you are going to see damage and suddenly you notice that you have to apply some pressue on side to make sure connection is made.. Not to mention that there is danger of prying connector loose from board - something you do not want to happen.

        Wireless means there is going to be less mechanical damage. Thingie is going to have a bit increased lifespan. That seems worth it.

        • Well I have a pretty long history using electronic devices, including things like cellphones that you charge daily. Currently the total number of failed power connections I've seen due to regular mechanical wear is zero.

          I really do not believe this is a big deal.

      • by Stooshie (993666)
        " ... We just have to accept the fact that wires are here to stay for many things ... "

        We just have to accept the fact that square wheels are here to stay for many things

        There, fixed that for ya!
        • Ummm no. We have the round wheels right now. This is the square wheel that people ware trying to make roll well because they think it is cool, not because it works.

          See there is this little thing, called the laws of physics, might have heard of it, that starts to get in the way here. You cannot have wireless power over any large distance without severe loss. Not possible. For it to be possible, we would have to discover that our current understanding of physics is incomplete, and then apply those new theorie

    • by Twinbee (767046)

      My laptop power transformer is pretty light, and to me it would be worth the extra weight to allow me to rid the ubiquitous wire.

    • by Joce640k (829181)

      The standalone USB chargers have higher current, as do many of the newer PCs.

  • by iamacat (583406) on Monday September 13, 2010 @02:24AM (#33558826)

    In this day and age when we want to save energy, not mess up our environment, communications and bodies by leaking it to unwanted places? Standardize on USB charges instead and wire clutter will be kept to a minimum. I see important uses in implanted medical devices, waterproof equipment and other cases when direct physical access to the device is impractical. But for cell phones/laptops this is positively silly.

    • by Joce640k (829181)

      Yep. I could understand people getting excited if it charged the phone as you walk around the house or via the cell tower or something. This just gives you 10cm of extra distance, you still have to put your phone on it and leave it there to charge. If you're really too lazy to insert a plug (about three seconds) then a dock is just as simple and takes up less desk space.

      But that's not what it's about. It's about appearance. Messing around with wires and plugs makes you sound like a poor person.

    • by couchslug (175151)

      How dare you disturb my fantasy of Uncluttered Shiny!

      There can't be any health risks for a technology this cool. :P

    • I see important uses in implanted medical devices, waterproof equipment and other cases when direct physical access to the device is impractical. But for cell phones/laptops this is positively silly.

      These actually use alternating current (fields), not direct current, so it's constantly alternating between positive and negative.

  • by Twinbee (767046) on Monday September 13, 2010 @03:41AM (#33559046) Homepage

    In other related news, they've kept up a model helicopter in the air by transferring power by laser:

    http://www.brahmand.com/news/Mini-helicopter-flies-using-laser-power/4824/3/13.html [brahmand.com]

    Because of the inverse cube law for wireless power transfer, I think we'll ultimately be using this kind of laser technology in future, fitted to house ceilings and street lamps. If blocking obstacles become an issue, then the receiving device can also send a purely informational laser back to the source to make sure that it's okay to beam the power laser at it, and in this case the initial source power laser can be instantly shut off, similar to those 'SawStop' table saws that shut off in milliseconds if the hand gets in the way to prevent loss of fingers.

    • by drinkypoo (153816)

      Because of the inverse cube law for wireless power transfer,

      That only applies for broadcast, this is [almost] unicasting. Last I checked the technology used phased arrays.

      If blocking obstacles become an issue, then the receiving device can also send a purely informational laser back to the source to make sure that it's okay to beam the power laser at it, and in this case the initial source power laser can be instantly shut off, similar to those 'SawStop' table saws that shut off in milliseconds if the hand gets in the way to prevent loss of fingers.

      Even if laser power made sense (which it does not) this is not the way you would do it. You would add a data stream to the power laser, just as the signal on a sawstop system is gathered from the blade itself and not from a separate sensor. Data stream is affected, then power is being interrupted. It's either that or basically surrounding the power beam with the informational beam, or an array ther

  • by kieran (20691) on Monday September 13, 2010 @04:30AM (#33559256)

    It's about time we started seeing waterproof phones and e-readers, and if the power is wireless and communication is wireless, there shouldn't be many more barriers to this.

  • That's lame... now if they used a laser, ...

  • Magnetic resonance (Score:3, Interesting)

    by kurt555gs (309278) <kurt555gs@ovi. c o m> on Monday September 13, 2010 @06:35AM (#33559670) Homepage

    People that live near high tension towers have put up coils to suck up stray power for years. The power companies frown on this, but my feeling is that it makes up for shortening peoples lives because of living next to these things.

    • feeling is that it makes up for shortening peoples lives because of living next to these things.

      You know that was debunked years ago, right? The original studies had massive flaws, and one researcher even admitted years later that he fudged results. Large scale studies since then have been conclusively negative.

  • Won't be long before someone will complain it is causing them headaches or some other medical problem.

  • by Ancient_Hacker (751168) on Monday September 13, 2010 @07:21AM (#33559876)

    This is a well-trodden area-- explored by many folks, starting with Tesla. Unfortunately there are several very basic phisical showbunglers if not showstoppers.
    Issues that are fundamental to electromagnetic radiation:

    (1) If you send out EM waves, the efficiency of the antennas is like 1% at low frequencies, wasting 99.99% of the power. If you use microwave frequencies, the antennas are much more efficient, but so is your body's ability to absorb the stuff, which is not a good thing.

    (2) If you try this near-field coupled resonator thing (first tried in 1886), you son find out it has very limited range, and you need coils as large as the distance to be spanned, and the power drops off as the square of the distance when near, as the cube of the distance a little bit farther away.

    These are basic Maxwell's equation impediments that are unlikely to ever be overcome.

     

    • by Shotgun (30919)

      Moderators, this is not informative, unless you did not know that ignorance prevails.

      1) this is called a "transformer". There have been a few in use since Westinghouse ran Thomas Edison out of the power production business. Some experienced power plant engineers think they're actually useful at 60Hz, and are a little more efficient than 1%.

      2) that is why the charger is a pad that you lay the mobile device on when the device needs charging. The coupling distance is very short when THEY ARE IN PHYSICAL CO

  • What do I need wireless charging eyes? I already have two wired ones, and they work perfectly.
  • by famebait (450028)
    I never thought I'd see a resonance cascade, let alone create one.
  • I saw this same concept demo'd on the TED podcast by an american company over a year ago: http://blog.ted.com/2009/08/25/wireless_electr/ [ted.com]

Every nonzero finite dimensional inner product space has an orthonormal basis. It makes sense, when you don't think about it.

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