Short History of LED Lighting


48 points | by blast 14 days ago


  • ChuckMcM 13 days ago

    Okay, that was useless.

    Summary: LED Lighting is now called Solid State Lighting (SSL) and improving lighting efficiency is no longer and issue. So other ways to differentiate are being sought.

    While that could be a good launch paragraph into an interesting article, that is where it stops.

    • wombatmobile 13 days ago

      Yeah, the fact that LED bulbs can change color and be connected to networks and sensors means they can exhibit behaviour. I thought TFA was going to discuss automation or integration.

    • falcolas 13 days ago

      What blows me away is that you can now get a watch which is constantly illuminated by LEDs and they're claiming "up to 3+ years" of battery life.

      LEDs are slick.

      • remilee 13 days ago

        Shouldnt be "history of led" should be future lol

      • tyingq 13 days ago

        They talk a lot about the blue LED, but don't mention one reason that it's important.

        What's important is white LEDS, probably the most used color. There isn't really a white LED. They are either three LEDS (R/G/B), or a blue led with some phosphor coating.

        • milesvp 13 days ago

          So true. I'd love a miracle material that doesn't require a phosphor coating to get full spectrum lighting. Maybe some meta-material will come out in the next decade...

          Meanwhile, these guys keep popping up when I search for LED spectrograms. They seem to have good phosphor coatings for their LEDs. It's certainly one of the better spectrograms I've seen for an LED lightbulb.

          • sephamorr 13 days ago

            One answer is to stack 3 LEDs on the die, each tuned to the center wavelength of human photo-receptors. Existing RGB LEDs emulating "white" suffer from shadowing effects where shadows have a color based on the parallax between the red, green, and blue elements in the light bulb. This is no longer an issue if you co-locate the emitters.

            • lathiat 13 days ago

              This works for direct illumination (eg an LCD screen) but fails for reflected light (eg a light).

              This video from Technology Connections helps explain

              • jrwoodruff 13 days ago

                Technology Connections is the bomb. I think I've watched all of his videos at this point, highly recommend his channel.

            • MayeulC 13 days ago

              Not sure you want full spectrum lighting, that would likely reduce the perceived luminosity (not sure about this? How much do rods contribute to it?).

              For more efficient color conversion, try quantum dots. You could likely replace phosphor coating with it.

          • contingencies 13 days ago

            What's interesting to me is that LEDs were apparently a Russo-Japanese invention yet the industry is now completely dominated by China. LED lightshows of an evening are a very late naughties China thing, every town has one these days, hell almost every building has one. Makes for interesting skylines, but no doubt terrible for ambient light pollution, insect life, etc.

            • mattgrice 13 days ago

              China dominates most electronic industries, few of which were invented there. Interesting that you say LEDs are a Russo-Japanese invention because all colors of LED were first commercialized in the US. The high-brightness blue LED was discovered in the US but commercialized by a Japanese company.

              • sephamorr 13 days ago

                When Shuji Nakamura developed the high-brightness blue LED, he was working at Nichia, in Japan. He's now at UCSB.

            • wombatmobile 14 days ago

              I installed Lifx bulbs in the main living area of my house. They are controlled by wifi through an ios app that can change the color and intensity of each bulb. I schedule sleep mode at 10.30pm and normal intensity at sunrise.

              If I want to override the schedule at night I just turn the wall switch off/on and the bulbs wake up.

              I like these wifi LED lights. They are the most reliable aspect of my life.

              • ponker 13 days ago

                I think that most people vastly underestimate how important lighting is to a living space. I frankly think that a $500K house with great lighting feels like a much bigger, higher-end $1 million house.

                Get lots of high-CRI lighting, at daylight and warm white color temperatures, have them automatically shift from blue to red on a daily basis. If you can't do a permanent installation, get those 5-arm floor lamps.

                • ponker 13 days ago

                  Ydz- you replied this comment with a very useful comment that is “dead” either because you were downvoted (impossible) or because the megalomaniacs who run this site consider you persona non grata.

                  • contingencies 13 days ago
                    • ydz 13 days ago

                      While it's usually okay to assume that a light source with a high CRI offers better looking light than one with a lower CRI, that assumption can be incorrect.

                      CRI is a measurement of color fidelity, i.e. how closely a light source renders a specific color as compared to a reference light source, which is either daylight or an incandescent lamp, depending on the correlated color temperature of the light source we're measuring.

                      One problem is that CRI is measured by evaluating color fidelity over only 8 color samples, mostly pastels. Some argue that 8 sample don't have enough coverage, esp. when it comes to reds, which are important for rendering skin tones. The missing red color samples is the reason why folks started using R9 as a metric in addition to CRI.

                      Another problem is that high color fidelity in a light source is not always positively correlated with user preference. For example, there have been light sources developed to render colors in a more saturated way than daylight or incandescent light, which gives them a low CRI but users preferred them to higher CRI lights.

                      The solution has already been proposed: TM-30, which is a new standard that measures both color fidelity, Cf, and color gamut, Cg (essentially color saturation), and also uses 99 color samples instead of CRI's 8. You can read more about TM-30 in the paper here:

                      Or in this product page if you want a more concise explanation:

                      The catch is that TM-30 has not been widely adopted, and CRI is still being used, probably because industry folks find TM-30 to be too mathy and hard to understand.

                      Source: I'm a former lighting professional turned software developer.

                    • adzm 13 days ago

                      The Nobel Prize was awarded to them in 2014 fwiw, not 2004.

                      • wombatmobile 13 days ago

                        TFA actually says "So significant was this discovery that in 2004, the trio would receive the Nobel price in Physics."