Slashdot Mirror
UCLA Engineers Create Energy-Generating LCD Screen
An anonymous reader writes "Engineers at UCLA have developed technology that allows gadgets like smartphones and laptops to convert sunlight, ambient light, and their own backlight into energy. Equipping LCD-enhanced devices with so-called polarizing organic photovoltaics will recoup battery loads of lost power, and enable smartphone users to scour Yelp, scan Twitter, and update their Facebook page without fear of draining the charge before a real communication crisis arises."
it isn't perpetual motion... it is energy recapture. You really think that all the light generated by the LCD backlight is
1) transmitted through to your eye
2) used at 100% efficiency
I think you have a good point. Anything that captures the photons by necessity is going to filter said light and therefore what reaches you is going to appear darker for that "setting" than it would without the filter. It is highly, highly, HIGHLY unlikely that there is somehow a way to get more energy out of "recouping" the backlight through that filter than would have been reserved simply by running the battery at the lower light level that corresponds to the diminished level of light reaching the user.
"Stratigraphically the origin of agriculture and thermonuclear destruction will appear essentially simultaneous" -- Lee
Except it's doubling as a polarizing filter which is fundametally needed by LCDs and hence you already have the energy loss.
LCDs work by creating a whole bunch of light, and then filtering out the light that isn't needed. That's why black isn't truly black on LCD screens -- the backlight is still on, the screen is just filtering out as much light as it can. If they have a way to recapture that light, which otherwise goes to waste, then it will provide substantial energy savings, especially considering that the screen often consumes as much energy as the rest of the phone combined.
LCD forms images when the crystals align in a particular way to block the backlight. Now in addition to forming an image, those crystals blocking photos are tapped to recoup a charge.
As soon as I read the (crappy) summary, I knew there would be posts like this:)
The way LCDs work is that you have a constant back-light (halogen, LED, whatever), and then the LCD matrix blocks light for pixels that should be dark, while allowing light to pass for pixels that should be bright. This modifies the LCD itself to have photovoltaic properties, thus recapturing (some of) the energy from blocked photons in dark pixels, rather than wasting it as heat.
Couldn't they also invent a device that convert the kinetic energy of the wrist while in front of the computer screen?
The only way converting backlight to energy works is by stealing photons (effectively dimming the display), and putting it through a level of inefficiency.
You're assuming they're stealing it from the final output. What they've actually done is replace the standard polarizing filter that LCDs use with their own filter that captures the filtered photons. Those photons are already being lost by design , so capturing them is entirely beneficial. For a quick car analogy, think of it as a flywheel for your LCD. You're going to be doing something that consumes energy anyway, and most of that energy would be wasted otherwise, so you might as well make a point of capturing some of it for your use. Plus, the article indicates that as much as 75% of the energy is lost to polarization, so there's plenty of light to grab there.
Sure. It won't be as fast as charging it from a power strip that is plugged into itself, but it should do fine when out and about.
Kid-proof tablet..
Really? So when I have the backlight fixed at 100%, and display a screen of all black except for one white pixel, that pixel will be very, very bright? I don't see that effect on either of the LCDs in front of me (one TN, one IPS).
Or are you saying that the brightness of the pixels on one side of the screen affect the brightness of those on the other half? I don't see that, either.
Perhaps neighboring pixels? Nope - can't say I've seen that happening.
So. [citation needed], if you don't mind.
Kid-proof tablet..
Because it also captures ambient light from external sources into energy. (Outdoors, energy from sunlight would vastly outweigh anything recaptured from the backlight). Perhaps you could make an e-reader that *never* needs recharging under typical usage patterns. The Kindle already lasts a long time, but dispensing with the charging apparatus altogether would be pretty cool.
i don't think it will uninstall itunes
This is a joke. I am joking. Joke joke joke.
It would be more efficient to only light the pixels that need lighting, like say, OLED. Need more work in that dept.
But I guess recovering some amount of power is superior to not recovering anything, it's just never going to be as efficient as using less power in the first place.
Sent from my PDP-11
You could put a puny calculator solar charger on a Kindle and it would keep it powered forever. I have no idea why there's no solar powered e-readers in the US market. I saw a Korean prototype once, but why not in the West befuddles me.
Come on. You can't power a phone from the energy of the phone's own display. That would be like living off your own...*OK--that is so gross I can't even make the joke in a feeble attempt at /. Karma* Wait, I just made the joke, while not making the joke andapologizing for not making it. I guess you can make something from nothing.
Skepticism withdrawn.
If you can't control how much dimming these provide by capturing photons, on an individual basis, then your point is moot.
You can control that. This is a polarizing filter, just like the one that's there now. The polarizing filter is there to filter out the light that has had it's polarization rotated by the LCD layer. LCD layers themselves are very transparent, they do not block light themselves. They get polarized light, rotate the polarization and send it through another polarization layer. If the polarization of the light is rotated (the LCD layer is "on") the light is absorbed by the filter (or just a part of it. Depending on how much it's rotated). The difference between this new polarization layer and the old one is that the old one absorbs the light and converts it to heat. The new one converts some of it to electricity.
See the wikipedia page
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.
But I guess recovering some amount of power is superior to not recovering anything, it's just never going to be as efficient as using less power in the first place.
Were it not for the added entropy from generating heat, recapturing energy from the display would be exactly as efficient as using less energy in the first place. However if they implement this technology well, they could have it capturing energy from external sources as well as the screen. Efficiency wouldn't need to be terribly high for it to actually extend battery life better than decreased expediture would. It could even go as far as to recharge your device provided your device saw enough downtime.
So while it would also be a good idea to cut down the inital energy expediture, don't underestimate the potential of this technology. I can see this one going places.
Cool post bro, highfive \o