People can be very susceptive to some lighting phenomena.
Most known are the rainbow artifacts with dlp projection systems where after a white lightsource a colorwheel with multiple (order of 7) colors rotate for a digital mirror device (DLP) to create an RGB color picture.
Some people get headaches after a few minutes and they continually see rainbows others have no issue at all, until they shake their heads and the rainbows appear.
I spent a summer holiday when at school doing detailed spectral response measurements of fluorescent tubes in a lab at Thorn Lighting. I never found a tube with any discontinuity in the spectrum.
Maybe it's an artifact of moving to more modern Tri-phosphor coatings in the quest for increased efficiency? (Just picking up on the Thorn reference).
Most of the phosphors I worked with in the 70s at Thorn already used multiple rare earths. One of my tasks was to measure sample tubes of various colours off the production line, to check that their phosphor mixes were staying in spec. Supply a few truck loads of off colour tubes to a clothing chain, they get massive returns of the "it didn't look this colour when I tried it on in the shop" kind, and people lose their jobs. Look at the example rare earth spectrum at https://en.wikipedia.org/wiki/Fluorescent_lamp . There are no gaps in that. Each of the rare earth phosphors has quite a wide spectral spread, and they overlap.
I dunno then. It's hard to see how a spectroscope can lie.
EDIT: Although that gappy Red, dirty Yellow, Green, Blue, Violet looks very familiar...
https://en.wikipedia.org/wiki/Fluorescent_lamp#/media/File:Fluorescent_lamp_spectrum.jpgEDIT1: Just tried the CD trick and it clearly shows up the gaps in the florescent spectrum, it's a bit fuzzy due to the lack of a slit but it's good enough if you get the angle right. Time to compare your Fluorescent and LED spectrums folks (assuming you haven't all gone HDD).
I much prefer LED bulbs with the Edison screw that can be replaced.
At least the integral designs generally come with proper switchers, not flickery capacitive/resistive troopers.
As I've said before the EU should have standardized a low voltage DC socket and used their own buildings to jumpstart the market. They should have done that long ago, but even now it would still help.
I much prefer LED bulbs with the Edison screw that can be replaced.
At least the integral designs generally come with proper switchers, not flickery capacitive/resistive troopers.
As I've said before the EU should have standardized a low voltage DC socket and used their own buildings to jumpstart the market. They should have done that long ago, but even now it would still help.
There certainly needs to be a change in the way lamps are built. Its more than just a matter of using a proper power supply. Most screw in LED bulbs get too hot to be reliable, because they have so little space for radiating away the heat. They need more area to spread out the heat, especially if the bulb is to be in an enclosed luminaire.
There certainly needs to be a change in the way lamps are built. Its more than just a matter of using a proper power supply. Most screw in LED bulbs get too hot to be reliable, because they have so little space for radiating away the heat. They need more area to spread out the heat, especially if the bulb is to be in an enclosed luminaire.
It's not ideal, but being able to fit in the millions of existing fixtures justifies the engineering compromises necessary to make an LED "bulb", which really are not so bad in many cases. I still have Philips and EcoSmart LED bulbs I bought in 2011-2012 that have been in dusk till dawn service ever since and still look the same as the day they were installed.
The other changes are happening in the form of new integrated LED light fixtures that have no bulb. Like anything else, these range in quality from excellent commercial grade stuff to garbage you can get for a few dollars.
Most of the phosphors I worked with in the 70s at Thorn already used multiple rare earths. One of my tasks was to measure sample tubes of various colours off the production line, to check that their phosphor mixes were staying in spec. Supply a few truck loads of off colour tubes to a clothing chain, they get massive returns of the "it didn't look this colour when I tried it on in the shop" kind, and people lose their jobs. Look at the example rare earth spectrum at https://en.wikipedia.org/wiki/Fluorescent_lamp . There are no gaps in that. Each of the rare earth phosphors has quite a wide spectral spread, and they overlap.
The rare earth phosphors were instrumental in making compact fluorescent lamps and white LEDs. The old halophosphate phosphors could not tolerate being driven as hard as required in a small lamp. Even the big T12 lamps deteriorated somewhat quickly in VHO (1500mA) and to a lesser extent HO (800mA) types.
There is a relatively new (but expensive) white LED technology that uses a violet LED (410 nm) plus three phosphors. The light generated is very close to natural daylight. Museums, art galleries, and luxury stores use them. I have heard that some professional athletes are experimenting with this lighting at home, since it seems to promote better sleep:
https://journals.sagepub.com/doi/full/10.1177/1477153519828419
Does anyone manufacture bulbs using violet LED's and 3 phosphors?
Most known are the rainbow artifacts with dlp projection systems where after a white lightsource a colorwheel with multiple (order of 7) colors rotate for a digital mirror device (DLP) to create an RGB color picture.
Some people get headaches after a few minutes and they continually see rainbows others have no issue at all, until they shake their heads and the rainbows appear.
I used to hate the early DLPs for that, but they have since managed to increase the color switching frequency enough for it not to matter anymore, I use a DLP projector in my room and I only very occasionally see a slight color banding if I like flip myself around fast in my bed. On old ones just moving eyes from a part of the image to another was enough to make it very visible.
Just a thought - not properly filtered LED lighting is not dodgy, it's just crap that could be potentially dangerous.
The mere fact that in some cases, you should not look at it directly is insane. If you're dealing with lasers, that's good sense and perfectly understandable. If you're dealing with indoors lighting, that's just stupid and irresponsible from manufacturers. Just fucking add filters. Commodity lighting was not meant as a weapon last I checked.
As to outdoors lighting, their brightness and wide spectrum is a delight for surveillance cameras.
You should never look directly in too bright light sources, be it incandescent, led, lasers or the sun.
Just a thought - not properly filtered LED lighting is not dodgy, it's just crap that could be potentially dangerous.
The mere fact that in some cases, you should not look at it directly is insane. If you're dealing with lasers, that's good sense and perfectly understandable. If you're dealing with indoors lighting, that's just stupid and irresponsible from manufacturers.
You can damage your eyes by staring directly into an old fashioned incandescent penlight if you work at it. Or the filament of an ordinary domestic incandescent bulb. It's not going to instantly burn your retina if you glance at it and neither will the LED but you don't want to stare into it.
Just a thought - not properly filtered LED lighting is not dodgy, it's just crap that could be potentially dangerous.
The mere fact that in some cases, you should not look at it directly is insane. If you're dealing with lasers, that's good sense and perfectly understandable. If you're dealing with indoors lighting, that's just stupid and irresponsible from manufacturers.
You can damage your eyes by staring directly into an old fashioned incandescent penlight if you work at it. Or the filament of an ordinary domestic incandescent bulb. It's not going to instantly burn your retina if you glance at it and neither will the LED but you don't want to stare into it.
We are both staring into LED's right now.
Does anyone manufacture bulbs using violet LED's and 3 phosphors?
The technology is called TRI-R and was developed by Toshiba Materials:
https://www.toshiba-tmat.co.jp/en/tri-r/about/index.html
Seoul Semiconductor manufactures SunLike LEDs using this technology:
http://www.seoulsemicon.co.kr/en/technology/Sunlike/
DigiKey carries SunLike LEDs and COBs:
https://www.digikey.com/products/en?keywords=sunlike
Knema offers modules with SunLike LEDs:
https://www.knema.com/high-cri-for-the-best-color.html
Some LED bulbs on Amazon use the word 'sunlike', but no confirmation that they are SunLike LEDs. There's a press release about Seoul making a deal with Mimi Lighting, but no sign of actual products from Mimi (they might be Korean-only).
Sceptre
Thanks for that.
I noticed this on Knema's site:
Eye Safe High CRI SunLike LED Lighting
I have noticed lots of manufacturers involving LED's using similar terms in recent years such as
healthy, eye-care, eye-health, low blue-light, flicker-free, and so on. So I have to wonder, if current and previous LED tech is so safe, why all the marketing toward safer LED technologies? And why have so many people such as myself experienced eye strain, eye fatigue, and/or general eye discomfort from using LED displays and lighting? And for many people who get so-called 'computer eye syndrome', it seems that once you get it you have it for good, meaning that you will be much more prone to eye issues from that point on. There is obviously an eye risk issue being addressed in the industry, yet no one admits that there was ever a problem, even though addressing the problem is a roundabout way of admitting the problem.
To me, it does seem that LED tech is dodgy to a degree.
There is some evidence suggesting that blue light tends to wake a person up and interfere with sleep. Largely the eye-safe marketing is just that though, marketing. LED bulbs are a fairly mature technology and the price has fallen dramatically. How do you get people to go out and buy new more expensive bulbs?
The same as with any other light source, nothing's specific to LEDs in there.
Pst kid, you want to see some confirmation bias?
The same as with any other light source, nothing's specific to LEDs in there.
It really is specific to LED's. It is in the title and the first sentence:
IEC/EN 62471 for LED Lighting Products
Standards for Eye and Skin Safety
As LEDs become widely used in many LED lights, assessment of the unique “Blue Light” hazard is critical
I have a hard time imagining how anyone could think otherwise.
Pst kid, you want to see some confirmation bias?
Admittedly, I do have a bias here, which has been developed through personal experiences with LED technologies. The first experience that I can remember was with LED flashlights years ago. No one wanted one of those things pointed at their eyes. The reaction to LED flashlights was much stronger than with traditional filament flashlights. The light from them was intense, very blue, and had lots of glare. The same was true with LED headlights. When those things came around, everyone complained about seeing them on the road. It was uncomfortable to the eyes and blinding to everything else on the road when those things were coming at you in the opposite lane. Then I got a laptop using LED backlighting, coming from a laptop that used a CFL backlit display and a desktop that used a CRT monitor. I never had any issues with the latter, other than sometimes getting red and dry eyes from the CRT after spending long hours in front of it. But within a year or two of using the LED backlit display, I got a wicked case of eye strain that physically made me feel sick, with aching eyes and feeling like I had the flu. I never had eye strain before that point, so I didn't really understand what was going on. After that, I got more cases of eye fatigue, but having experienced full-on eye strain, I knew enough to get away from the display before eye strain set in. As the years rolled on, I began seeing lots of mentions of blue-light and PWM eye hazards related to LED displays. And LED lighting became mainstream, followed by lots of people talking about feeling uncomfortable with LED lighting and potential hazards of LED lighting. At some point it began to be more difficult and more expensive to find the same range of incandescent/halogen bulbs (and CFL bulbs looked bad to me), and I decided to try LED lighting at home. But I still haven't found LED lighting that I feel comfortable with for reading and other tasks. It seems ok for me in less critical areas, such as hallways and porches. So yes, I do have a bias from these personal experiences with LED technologies. But I am still willing to explore newer LED technologies to see if there is something out there which might work for me, because LED lighting has obvious benefits of power efficiency and potentially lower cost over time.
It really is specific to LED's. It is in the title and the first sentence:
Read the doc.
IEC/EN 62471 is generic and has been there for ages, they just added that it obviously also applied to LEDs.
The same safety measures apply to all light sources (laser treated separately). Nothing new.
It really is specific to LED's. It is in the title and the first sentence:
Read the doc.
IEC/EN 62471 is generic and has been there for ages, they just added that it obviously also applied to LEDs.
The same safety measures apply to all light sources (laser treated separately). Nothing new.
Is there some place to download that whitepaper without a pay wall?
Admittedly, I do have a bias here, which has been developed through personal experiences with LED technologies. The first experience that I can remember was with LED flashlights years ago. No one wanted one of those things pointed at their eyes. The reaction to LED flashlights was much stronger than with traditional filament flashlights. The light from them was intense, very blue, and had lots of glare. The same was true with LED headlights. When those things came around, everyone complained about seeing them on the road. It was uncomfortable to the eyes and blinding to everything else on the road when those things were coming at you in the opposite lane. Then I got a laptop using LED backlighting, coming from a laptop that used a CFL backlit display and a desktop that used a CRT monitor. I never had any issues with the latter, other than sometimes getting red and dry eyes from the CRT after spending long hours in front of it. But within a year or two of using the LED backlit display, I got a wicked case of eye strain that physically made me feel sick, with aching eyes and feeling like I had the flu. I never had eye strain before that point, so I didn't really understand what was going on. After that, I got more cases of eye fatigue, but having experienced full-on eye strain, I knew enough to get away from the display before eye strain set in. As the years rolled on, I began seeing lots of mentions of blue-light and PWM eye hazards related to LED displays. And LED lighting became mainstream, followed by lots of people talking about feeling uncomfortable with LED lighting and potential hazards of LED lighting. At some point it began to be more difficult and more expensive to find the same range of incandescent/halogen bulbs (and CFL bulbs looked bad to me), and I decided to try LED lighting at home. But I still haven't found LED lighting that I feel comfortable with for reading and other tasks. It seems ok for me in less critical areas, such as hallways and porches. So yes, I do have a bias from these personal experiences with LED technologies. But I am still willing to explore newer LED technologies to see if there is something out there which might work for me, because LED lighting has obvious benefits of power efficiency and potentially lower cost over time.
You once loosely connected two phenomena and since that time you see the perceived issue pop up in various places? That could be the textbook definition of confirmation bias. It sounds a lot like the people who suffer greatly from electromagnetic radiation from real and imaginary sources.