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Breakthrough In LED Construction Increases Efficiency By 57 Percent
Zothecula writes: With LEDs being the preferred long-lasting, low-energy method for replacing less efficient forms of lighting, their uptake has dramatically increased over the past few years. However, despite their luminous outputs having increased steadily over that time, they still fall behind more conventional forms of lighting in terms of brightness. Researchers at Princeton University claim to have come up with a way to change all that by using nanotechnology to increase the output of organic LEDs by 57 percent.
All they've changed is how they contain it to limit the amount of light lose to absorption. I mean, to the user of LEDs the distinction is pretty irrelevant, but if you were wondering how you could improve on such a fundamental electrical component, that's how.
The article explains that the light extraction is increased from 3% to 60%. This is a factor of 20 increase in light output. So compared to a "normal" LED, this new technology is actually 2000% more efficient.
There is a company that makes lightdims, which are like tinting stickers that you can put over LEDs to dim them (block some of the light). They come in different strengths, even blackout.
I use them on the computers and other electronics in my bedroom since the LEDs collectively put out so much light it's hard to sleep.
...because it doesn't pay very well to sell you something that'll last forever, whether it's an Oled screen or LED bulb.
:(
It's no coincidence that the CFLs die off after 1-2 years albeit they're supposed to last 10-20 years with normal usage. My first Philips 11w CFLs that I bought 20 years ago, still glows like mad and simply refuse to die. That is back when the CFLs was new, and cost like 40 bucks just for ONE bulb, but hey...it's actually worth the money, it still is my best bulb.
With LED's, it's a walk in the park for the industry to make them last less, all you need to do for your LED to last less than specified, is to OVERDRIVE them just a little, a little higher current and the LED's will die rapidly, they should be able to make the new LED lamps last just out the warranty period (that in most countries AFAIK is around 3-6 months), or cheap enough to avoid the warranty altogether.
There is nothing wrong with the LED's themselves, (we're talking the components...DIODES...not the whole circuit with drivers and all), I ordered strong RGB leds from China many MANY years ago, they're still glowing on my homemade alarm-systems so strong that I can use them as night-lights, yes...4 years later 24H day use...they still glow enough to lit up an entire room. And I just used Ohms law + 1% resistor values to calculate the right resistor value for my circuits. You can pretty much BET the manufacturers will "miscalculate" these values, or make the drivers for the stronger LED's last MUCH less in order to keep pumping out new ones for the consumers to waste and waste.
I'd rather pay a proper price for my LED lamps - and keep our environment safe from this mad overproduction that now has escalated totally out of hands.
What this world is coming to - is for you and me to decide.
The real breakthrough in LED lighting is getting rid of electrolytic capacitors in the power supply. Those are currently the components with the shortest life. See "Elimination of an Electrolytic Capacitor in AC/DC Light-Emitting Diode (LED) Driver With High Input Power Factor and Constant Output Current" Variations on that technology are now going into production LED lighting units. This should push unit lifetimes up from 20,000 hours to that of the LEDs, 40,000 or so. (Provided the quality of the LEDs doesn't slip.)
Because people wanted to be "trendy" and "futuristic" and thus started putting blue LEDs (which only came out two decades ago) in their equipment. Red was dull and boring (being done way back in the 60s) as was yellow. Green as we know it today (rather than a sickly yellow-puke-green) was a mid-90's invention. Blue LEDs came out in the mid-late 90s.
So since they were so recent and popular, people stuck them on everything to show they were progressive.
A friend wanted to replace his landscape bulbs with LEDs, the flicker was horrible.
We added a bridge rectifier and the 120 hz flicker was less offensive.
So, we added a capacitor, the flicker was gone and the LEDs were much brighter.
I noticed they were also becoming warm so I measured the voltage which was now over 18vdc.
I suddenly recalled that a load resistor was always added when I used to make linear power supplies, a few years ago.
Can't remember the formula I used to use but google found a nice article about this:
http://mysite.du.edu/~etuttle/...
No brain, no pain.
Really what you're getting at is that red light doesn't destroy scotopic vision (ie night adapted vision) because the rod cells respond very little to red light. Notice I said respond very little, a bright enough red light will still have an impact. Using somewhat dim red light allows you to see things yet still retain your night vision. Even a brief moment of other light colors (ie white, blue, etc) will result in losing the night adapted vision which can take up to 30 minutes to fully recover.
That might qualify for the only time I didn't find Bob Saget infuriatingly annoying.
Better known as 318230.
Nope.
(Note: I use electronics and data processing terms as an analogy.)
The way your optic nerve pre-processes images before sending the signal onward to the brain causes you to see things at about 13 FPS, per object, asynchronously, with interpolation. What that means is that your optic nerve pre-processes "objects", typically by high-contrast divisions (this is the mechanism that camo tricks). After that, it updates "fields" corresponding to those objects projected against the optic nerve at a rate of ~13 times per second. It does this on a ~6.8 Hz clock (doubled, so 13.6 FPS, actually) embedded into the cells of the optic nerve itself. It polls the retina per field-clock, asynchronously, updating field assignments as it processes each result (different-contrast areas are pruned around the edges of fields and lumped into adjacent fields). Then the object data bundles are forwarded to the brain's optic processing center as they're completed.
Once in the brain, interpolated data is invented based on balance and motion data from other sensors. Thus, "motion blur". This is not the same as persistence of vision, which is essentially "burn-in" on the retinal cells.
The reason you see flickering is entirely different. The eye doesn't just sit there and gather light. It actively scans across things laterally. This scanning is done on that same ~6.8Hz clock. So the "frames" observed are frame-left and frame-right, alternating. This also feeds into the interpolation calculations.
Since LED's are tiny pinpoint light sources with a very high contrast gradient to anything around them, they can "escape" the interpolation post-processing done by the brain by falling outside of the re-fielding threshold during the object pre-processing done in the optic nerve. But, in order for re-fielding to work, it has to have something to compare to. That's going to be the burnt-in image from the previous frame. Re-fielding compares the fading burn-in with the current active signal. If your eyes have poor persistence, then you're going to have more re-fielding threshold misses, and thus more flickering problems.
The reason this doesn't happen to everyone all the time is because 1) everyone's eyes are a little different, especially the thresholds and timings used in re-fielding, and 2) LED's are engineered to work without visible flicker for most people.
I wouldn't be surprised if blue at night were murderous if our eyes are indeed compenssting by adjusting towards higher blue sensitivity near dawn or dusk when there's not much blue in the incident light.
If you came to that conclusion on your own, I'd congratulate you on (possibly) being extremely perceptive, but also surprised that you weren't aware that it's already been widely reported in the past few years that, yes, blue light is apparently very bad news from the point of view of being sleep-inhibiting:-
Example story
Blue light presumably being far more of an issue in recent years due to (a) the increase in use of electronics and (b) the blue LED fad. (*)
I've seen an alarm clock with blue numbers- presumably because blue LEDs are cool!!!!!!11111- which struck me as an absolutely horrible idea. As did a ******* blue-coloured baby nightlight (because even baby deserves to be kept awake by fashionable blue LEDs. Sheesh.)
(*) FWIW, the blue LED fad seems to have died down in the past couple of years, and white LEDs are the new hotness. Which is a good thing from an aesthetic point of view (**) but I suspect those white LEDs still contain a lot of blue. Especially the more bluish-white ones which may well just be blue ones with phosphor coating (as some "white" LEDs apparently are).
(**) Nothing against blue LEDs as a concept, it's great that they were invented. What I hate is their gratuitous use- or rather, misuse- in consumer goods, both because they're overused and the novelty wore off long ago, but also because they're far more distracting in context than red ones ever were.
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While it seems like a good idea to have a low voltage circuit, there some unfortunate realities that have to be taken into consideration. Mainly you need much thicker wiring to keep your resistive losses low. It's actually cheaper to have a transformer in the light fixture itself than it is to run heavy guage wire everywhere. https://en.wikipedia.org/wiki/...
So lets pretend that we've just completed writing this code, as opposed to having just completed sabotaging it -Altera