3 ms·
>Sadly like Moore's law, LEDs aren't getting much better anymore. The best LEDs are now remarkably close to the theoretical maximum luminous efficacy. We're no
by jdietrich 10y ago
>Sadly like Moore's law, LEDs aren't getting much better anymore.
The best LEDs are now remarkably close to the theoretical maximum luminous efficacy. We're now bottlenecked by batteries and the limits of sanity.
Specialist diving companies will happily sell you a 60w, 6300 lumen flashlight. It's not a big market, but it exists. To run a light like that you need a massive external battery pack tethered with an umbilical, because it'll eat through the entire capacity of an 18650 cell in under 10 minutes. That's no problem for divers, because a properly designed battery pack is close to neutrally buoyant; it's a major inconvenience for people on the surface.
1000 lumens is Good Enough for 99% of users of handheld flashlights. There really aren't that many people who need to throw a beam for half a kilometre or light up a football stadium with a flashlight.
- jwr 10y ago> The best LEDs are now remarkably close to the theoretical maximum luminous efficacy. Do you have any pointers/references where I could read up on this? I'm designing home lighting with power leds and finding that despite all the hype, it's quite difficult to beat the efficiency of TL5 HE fluorescent tubes with LEDs. I also noticed that while the output in lm/W has been increasing, it seems to increase very slowly these last few years.
- jdietrich 10y agoDepending on acceptable bandpass and desired color temperature, a white light has a maximum luminous efficacy of 250–370 lm/W. Nichia currently offer a white LED that achieves 210 lm/W at >80 CRI. Cree have high-flux LEDs capable of ~200 lm/W at >70 CRI. There's room for improvement, but nothing revolutionary. Cree had a prototype device achieving 303 lm/W in 2014, but it isn't currently commercially viable. Lower efficiency LEDs still make up a large proportion of the market for simple reasons of cost. https://arxiv.org/pdf/1309.7039.pdf https://arxiv.org/pdf/1309.7039.pdf https://www.nichia.co.jp/specification/products/led/NF2W757G-F1-E.pdf https://www.nichia.co.jp/specification/products/led/NF2W757G... http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/Data%20and%20Binning/ds%20XPL.pdf http://www.cree.com/~/media/Files/Cree/LED%20Components%20an... http://www.cree.com/News-and-Events/Cree-News/Press-Releases/2014/March/300LPW-LED-barrier http://www.cree.com/News-and-Events/Cree-News/Press-Releases...
- jwr 10y agoThank you — this is much-appreciated information and interesting reading.
- Bartweiss 10y ago> There really aren't that many people who need to throw a beam for half a kilometre or light up a football stadium with a flashlight. And for most people, a product that can do that is substantially worse than one that can't. If you want a flashlight to play tag, walk the dog, or wander your house in a power outage, you probably can't use a dive-strength light. We're finally hitting the point where even modest, internal-battery flashlights can be so powerful that they're painful to look at, and for most people you don't want to go any brighter than that.
- Dylan16807 10y agoThat's not a major problem. It's trivial to let it click to a different brightness, and then the battery will last all day.
- apk17 10y agoI wish. Flashlights tend to have all sorts of strange UIs, just like television firmware are just exploring the possible ways of being annoying. None of mine have both a way of getting full power fast /and/ deterministically turning it on on the lowest setting. (Except for the one that only has 'very bright' and where I first wondered why there is no rebound when I turn it on.)