One interesting application for super-bright LED's is home theatre projectors. Until very recently such projectors used lamp modules (usually metal-halide) that typically have an operating lifespan of a few thousand hours at most. That's a very rough estimate. Failures can happen sooner and they occasionally implode. Also, brightness usually drops off gradually as lamps age. New lamp modules usually cost a few hundred dollars. These lamps also produce a large ammount of heat and require active cooling, which makes projectors noisy unless carefully designed for quiet operation. For these reasons, home theatre projectors probably remain more of a niche product than they might otherwise be.<p>LED based lamps are starting to show up in this market sector. Current LED-based projectors are mostly portable projectors that offer low brightness and poor image quality, but some home theatre models of decent quality are starting to appear. At present, they're expensive, less bright than most projectors based on traditional lamps, and still require fans for active cooling. However, as LED's become more power efficient and economical, these projectors will hopefully become brighter, passively cooled, and significantly cheaper.<p>Projectors are not appropriate in many environments, especially those with high ambient light levels, but LED's may help them make major inroads into the big-screen market.
Related: "Drowning in Light" from a few weeks ago: <a href="http://nautil.us/issue/11/light/drowning-in-light" rel="nofollow">http://nautil.us/issue/11/light/drowning-in-light</a> <a href="https://news.ycombinator.com/item?id=8344769" rel="nofollow">https://news.ycombinator.com/item?id=8344769</a><p>It makes the compelling argument that people are addicted to light. "Tsao calculates that, as a result, light represents a constant fraction of per capita gross domestic product (GDP) over time; the world has been spending 0.72 percent of its GDP for light for 300 years now. If there are other energy markets that show a constant percentage of GDP expenditure over time, Tsao doesn’t know of them."
Certain things are cheap in the rich world that are expensive in the 3rd world. Sewage, electricity, and water are so cheap in the 1st world, that we don't think about the cost.<p>The first time I saw 100% adoption of compact fluorescents was in Cambodia. They pay $.40/KWhr. That is insanely expensive (unless you live in Germany).<p>Lighting technology disproportionally benefits the poor rather than than the rich. Anyone that works on it is my hero. My family bought power for $.04 KW/hr, so I could study at night.
I'm genuinely curious whether new homes will start wiring lighting for DC to accommodate all these new LED bulbs? I just don't have a good sense whether its more efficient to transform AC to DC at a central hub in the home to distribute to all rooms, or more efficient to do it at the bulb itself.
One problem with current popular LED bulbs:<p>They emit more blue light than incandescent bulbs [1]. If people light their households with LED lights at night, it might shift their circadian rhythms [2]. Screwed up circadian rhythms can have all sorts of negative health/productivity effects.<p>[1] <a href="http://www.designingwithleds.com/measuring-light-quality-philips-cree-led-bulbs-spectrometer/" rel="nofollow">http://www.designingwithleds.com/measuring-light-quality-phi...</a>
[2] <a href="https://justgetflux.com/research.html" rel="nofollow">https://justgetflux.com/research.html</a>
Exponential growth is awesome! However, I was curious about the maximum theoretical lumens per watt to determine when the growth will fall flat. A current LED bulb gives about 60 lumens per watt. While an ideal monochromatic light source could give 683.[1] So it looks like there is _only_ one order of magnitude left in efficiency gains.<p>1: <a href="http://en.wikipedia.org/wiki/Luminous_efficacy" rel="nofollow">http://en.wikipedia.org/wiki/Luminous_efficacy</a>
He makes some dubious efficiency claims. It's true the colored LEDs have always been pretty efficient, but that's no use lighting your home. White LEDs have surpassed incandescent bulbs but still have a way to go to reach flourescent tubes and the grand-daddy of efficiency - gas discharge lamps.<p>One (the?) reason for low power levels is they generate so much heat and are difficult to cool. LEDs are still primarily heaters - useful in the winter.
Several years ago I designed 1,500 W LED-based light source using extremely tightly packed LED's. Thermal management was a huge challenge. It took over three months of constantly running FEA thermal tests as well as physical tests to zero-in on an innovative approach to cooling the array. Crazy project. The surface of the emitter was measured at over 60,000 candelas per square meter. You simply could not look at the thing directly, it was really dangerous, almost like working with lasers.