Does LED lighting count as a dodgy technology? - Page 1
Forum section: electronics / general

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 24, 2019, 05:12:53 am
content: I'm sure that some of the tech involved people at the eevblog forum know that LED lighting bothers some people's eyes. And there have been studies showing that LED lighting can actually irreversibly damage the eyes. So do you think that LED lighting should be included in the category of dodgy technology? Maybe this will come off as a provocative topic, since LED lighting has more and more become the norm and we're all using it to some degree.I have been looking at a screen most of the day searching for lighting solutions for a bench. My eyes are toast.

author: james_s
author_rank: Super Contributor
timestamp: September 24, 2019, 05:17:50 am
content: LED lighting dodgy? It's the entire future of lighting and has already displaced nearly everything else. Good quality LED lighting is available that can rival any other artificial light source out there and even a lot of the low cost stuff has gotten quite good. It is efficient and long lasting too, I fully retrofitted my house to LED back in 2011-2013 and the only failures I've had in that whole time were a couple of bulbs I used in fully enclosed fixtures despite the fact they warned not to. There's nothing dodgy about LED, it's mainstream, in 2019 outside of certain specialized applications there's no reason to consider anything else.

author: Halcyon
author_rank: Unknown
timestamp: September 24, 2019, 05:24:50 am
content: Quote from: scatterandfocus on September 24, 2019, 05:12:53 amDon't look directly into bright or UV light sources, LED or otherwise as they can damage the eyes.

author: Kjelt
author_rank: Super Contributor
timestamp: September 24, 2019, 10:22:07 am
content: Nothing dodgy about the tech in it self.Perhaps some companies make dodgy lighting with small spectrum solutions or bad diffusors or low quality electronics, but that is not the tech it self it is the implementation.The only thing bad about LED lighting are the white outdoor luminaires that proven disturb wildlife.You can also say why wildlife should live in the vicinity of outdoor luminaires.

author: SeanB
author_rank: Super Contributor
timestamp: September 24, 2019, 12:24:13 pm
content: Not a dodgy tech, just dodgy implementation to cut cost as much as possible, and sadly the big names are also doing this to compete, making them with a similar lifetime to the incandescent lamp they are replacing. You should be able to have the LED fixtures have a lifetime in the order of decades, like the discharge lamps are capable of, with almost no loss in efficiency, but the desire to cut a cent of the price of all parts means that the actual LED units themselves are run at high current, hight heat, and thus at a lower efficiency, and with a much shorter operational life, while you can easily derate properly and use the same parts to get light output equivalent, but with a lifetime in decades. Just will cost double the price, and will use marginally less power as well, so long term you will have a lower TCO, but the only thing seen is the initial price, not the long term cost of short life, frequent replacement and higher power use.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2019, 01:05:08 pm
content: Quote from: scatterandfocus on September 24, 2019, 05:12:53 amHave your eyes really been affected, or are you just tired after a long day?

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 24, 2019, 01:26:29 pm
content: Quote from: coppice on September 24, 2019, 01:05:08 pmSince the advent of LED backlit computer displays, my eyes have been affected, and it seems permanent. I am easily prone to eye fatigue and strain, since. It seems to have gotten worse since LED lighting became the norm. I still use halogen bulbs at home in areas where light quality matters most, but I don't have any say elsewhere. I also have some 90+ CRI Cree bulbs at home (daylight and soft white) that are used in less critical areas, but when I try to use them in areas where I do lots of reading, they do bother my eyes over time. I have tried the high CRI GE bulbs too. 'High CRI' is a bit deceptive though, as CRI rating is a very small sample set of the full spectrum. LED lighting (even the highest quality) still has high peaks at a few bands. Also, only looking at CRI neverminds the effects of power switching schemes. I should probably try some Yuji bulbs, but it is hard to swallow those prices when the situation might turn out to be very much the same as the Cree and GE bulbs. And when looking at videos demonstrating Yuji lighting, I haven't noticed a great difference from the Cree and GE bulbs sold at local stores at much lower prices.Obviously not everyone is affected in the same way as I am. But I am far from alone too, as evidenced by so many blue-light blocking technologies available today, as well as manufacturers responding to blue-light and PWM complaints. And the rising demand for high CRI LED lighting says something about the situation.

author: Gyro
author_rank: Super Contributor
timestamp: September 24, 2019, 01:31:52 pm
content: Quote from: scatterandfocus on September 24, 2019, 05:12:53 amI'm not quite sure what you're asking. If it's looking at the LED backlit screen all day that has strained your eyes then that's an old problem, it was the same (or much worse) with CRT monitors. That's why employers are required to allow you time away from the screen to look at more distant objects. What you do at home is down to you of course. EDIT: I certainly developed eye problems in CRT days.If you're talking about LED lighting in general, then LEDs are efficient light sources and all light sources need to be applied properly for comfort. Don't stare at the filaments of incandescent lamps, there is far more IR energy, worst case you could burn your retinas or long term, develop 'glassblowers' cataracts from strong IR sources, or UV from unfiltered Halogen lamps come to that.LEDs (apart from powerful IR ones or UV ones) are pretty benign and certainly not 'dodgy'.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 24, 2019, 01:37:53 pm
content: Quote from: Gyro on September 24, 2019, 01:31:52 pmI have been using computer displays across the various display technology periods, as many others my age and older have. CRT, CFL, and LED. This isn't something that just happened yesterday.

author: dferyance
author_rank: Regular Contributor
timestamp: September 24, 2019, 01:52:48 pm
content: I had a few co-workers who insisted the florescent lighting gave them headaches. They convinced HR to essentially have the lights off in the office -- which applied to everyone. This wasn't that long ago so they were modern electronic ballasts where your eyes cannot pickup any flicker. Funny thing is, I get frequent headaches too but I don't jump at blaming the type of light bulb. If anything, I feel that sitting in a dark room looking at a bright monitor is uncomfortable. Humans are very prone to confirmation bias so we end up with essentially superstitious beliefs. So LED lights are bad and florescent lights are bad... maybe some people will think incandescent lights and candle lights are bad too.What I don't like with LED is that many fixtures now come with the LEDs as non-replaceable. I guess people find it convenient but both the LEDs and the electronics have a lifespan and can fail. I much prefer LED bulbs with the Edison screw that can be replaced.

author: Gyro
author_rank: Super Contributor
timestamp: September 24, 2019, 01:54:31 pm
content: Quote from: scatterandfocus on September 24, 2019, 01:37:53 pmSo yourQuotecomment is irrelevant to the discussion then? I'm sure you can understand how your OP could be confusing.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 24, 2019, 01:57:53 pm
content: Here is an old article on the issues of LED lighting:https://www.ledsmagazine.com/smart-lighting-iot/smart-cities/article/16699866/light-and-human-health-led-risks-highlightedHere is a forum based around the discussion of the negative effects of LED lighting:https://ledstrain.org/Keep in mind that it isn't a science oriented forum. It's mostly a bunch of users of LED displays who have been affected by it and who are trying to find solutions.Here is an interview of a researcher on the effects of LED displays on retinal cells:https://www.news-medical.net/news/20170330/Could-light-from-LED-screens-cause-irreversible-eye-damage.aspxObviously she is trying to pimp a specific blue-light blocking product, such is the world today.Here is a news bit mentioning a study on the effects of LED lighting on the eyes:Obviously, take all of this as a kick off point for further inquiry, not as definitive sources for information on the topic.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 24, 2019, 02:05:04 pm
content: Quote from: dferyance on September 24, 2019, 01:52:48 pmAt work most of the lights are fluorescent. And they do bother my eyes when reading under them. About 5 minutes at a time is all I can handle before my eyes hurt. A major part of that is that the lights are all overhead, directly over work areas. When I move off to the side, just out from under a light fixture, my eyes aren't bothered as much. But I didn't have this issue until after using LED displays for some years. I have been working under fluorescent lights since I was a kid in school and all of my adult wokrng life, as well as using CFL displays for some years. It seems to me that since using LED displays over more recent years my eyes have become more sensitive to artificial light intensity, where I much prefer dimmer reading lighting. It is supposed to be the other way around, where we need more light intensity for the same tasks as we age. And when I read outdoors in the shade, I am not affected at all (same as ever), which is where I do most of my reading and computing on a laptop, as weather allows.

author: Gyro
author_rank: Super Contributor
timestamp: September 24, 2019, 02:09:35 pm
content: I picked up an old Meiji direct view spectroscope of ebay a while back. The first thing I did (obviously) was to point it at various light sources.I first tried the fluorescent tube lights in the garage and kitchen and was unsurprised to find a collection of very narrow spectral lines, the same with various compact fluorescent ones.I tried the same thing with various white LEDs (bulbs and individual). I was expecting to see a strong blue component from the die and some compensating warming lines from the phosphor coating. In fact I found that the spectrum looked very smooth, with no obvious gaps or spikes. I found that really surprising.Daylight was pretty similar (obviously not able to accurately judge the colour temperature difference) with the exception of the fine black Fraunhofer lines.P.S. Filament lamps were boringly predictable, with a rolling off in the blue.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 24, 2019, 02:16:28 pm
content: Quote from: Gyro on September 24, 2019, 01:54:31 pmJust to be clear, I never once got eye fatigue from CRT or CFL displays. But I sure did get red and dry eyes from CRT's back in the day. I first got eye strain from an LED display (my first LED display, on a laptop), and I have been prone to eye fatigue ever since. I cut myself off well before eye strain can set in. And I have noticed that with some LED displays I can't read from them for more than a few minutes before my eyes begin to be bothered.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 24, 2019, 02:50:35 pm
content: Quote from: Gyro on September 24, 2019, 02:09:35 pmNow I want a spectrometer for my test gear kit. Thanks?

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2019, 03:00:49 pm
content: Quote from: Gyro on September 24, 2019, 02:09:35 pmA fluorescent lamp should give you a broad spectrum from the phophor and narrow lines from the mercury discharge. They use a glass which damps the UV lines from the mercury, but they still come through pretty strong when measured on a spectrometer. There have always been questions about the long term safety of those soft UV lines.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 24, 2019, 03:42:01 pm
content: Quote from: scatterandfocus on September 24, 2019, 02:50:35 pmLooking at spectrometers, now I ran into Theremino and Physicsopenlab. That stuff looks fascinating and could too easily take over all of a person's free time.

author: Gyro
author_rank: Super Contributor
timestamp: September 24, 2019, 05:09:22 pm
content: Quote from: coppice on September 24, 2019, 03:00:49 pmIt's a shame I can't capture a sensible photo through the small eyepiece. Yes, I was expecting a much more continuous spectrum - ok the lines aren't really thin, as you would see from single element lines but what I see is a band of Red, a narrower band of Yellow, one of green, and a broad band of blue, going into Violet. There are large empty gaps between them though.The Garage lamp is a relatively old, Argon (low temperature start) Philips 8ft 125W one, but the kitchen one was a relatively new (tube replaced within the last 5 years) 40W circular fluorescent. The colour bands were pretty much identical.I've since replaced the kitchen one with a nice GE LED dome fixture, and again what I see is a continuous spectrum. It's difficult by eye to distinguish theabsolutebrightnesses of every part of the spectrum but the thing is that it is a continuous spectrum with no gaps. That's what surprised me.The filament lamps (actually eco-halogen bulb replacements) have a continuous spectrum (which I would of course expect). There is blue present but no Violet, again as you would expect from the filament temperature.There are a few modern spectroscopes to be found on ebay, and probably educational suppliers, together with various designs on the web using CDs as diffraction gratings.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2019, 05:40:10 pm
content: Quote from: Gyro on September 24, 2019, 05:09:22 pmPhotos are useless for this kind of thing. You just capture the spectral response of the camera. You need to use a sensor with a flat spectral response. A lot of professional work is done with something like a rotatable diffraction grating shining through a narrow slit, onto a photomultiplier tube. Photomultiplier tubes can have a very flat response. Then you can sweep the visible band by rotating the diffraction grating, and get an accurate spectral plot of the source light.Quote from: Gyro on September 24, 2019, 05:09:22 pmI 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.Quote from: Gyro on September 24, 2019, 05:09:22 pmThe light from fluorescent lamps and white LEDs both come from similar kinds of phosphor. The spectra produced are not radically different in nature. You should expect a continuous, if rather uneven, spectrum, regardless of which colour lamp you choose.

author: james_s
author_rank: Super Contributor
timestamp: September 24, 2019, 05:58:16 pm
content: Quote from: dferyance on September 24, 2019, 01:52:48 pmI find the opposite is true for me, sitting in a bright room is uncomfortable, I like to work in subdued lighting, the actual lighting technology is irrelevant.Some LED backlit monitors use PWM dimming at a relatively low frequency of a few hundred Hz and that gives me a splitting headache. With better monitors this is not an issue at all.

author: Gyro
author_rank: Super Contributor
timestamp: September 24, 2019, 06:03:05 pm
content: Quote from: coppice on September 24, 2019, 05:40:10 pmThat's what I thought but I've been back and checked. No problems with the spectroscope though, as I said, it is clean enough to distinguish Fraunhofer lines (when it's not bucketing down with rain!).I just remembered another florescent source - the shop diplay lighting fixture that I used above my workbench before switching to a pair of Lidl LED batten fittings. It uses a pair of Osram whitedaylight(purchased by me, not specials) PL11 U shaped compact tubes. Again discrete Red, dirty Yellow, Green, then Cyan with a sharp transition to Blue and dull Violet with largish gaps between). There is one very sharp bright violet line at the top end, presumably the Mercury line. Any other lines must be hidden by the phosphors.Needless to say, the Lidl centre isle LED battens have a nice continuous spectrum!Edit:QuoteMaybe 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).

author: Kean
author_rank: Unknown
timestamp: September 24, 2019, 06:13:18 pm
content: If I was the OP, I'd be visiting my optometrist rather than sitting in front of a computer and posting on a forum.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 24, 2019, 06:22:31 pm
content: Quote from: Kean on September 24, 2019, 06:13:18 pmBeen there done that. He told me that there is nothing wrong with my vision that he is able to test, but that if I would like, he can prescribe me some blue-light blocking lenses with a slight magnification for computer use....wich are basically Gunnars or other brand.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2019, 06:54:50 pm
content: Quote from: Gyro on September 24, 2019, 06:03:05 pmMost 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 athttps://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.

author: Kjelt
author_rank: Super Contributor
timestamp: September 24, 2019, 08:19:11 pm
content: 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.

author: Gyro
author_rank: Super Contributor
timestamp: September 24, 2019, 08:31:10 pm
content: Quote from: coppice on September 24, 2019, 06:54:50 pmI 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).

author: Marco
author_rank: Super Contributor
timestamp: September 25, 2019, 12:01:46 am
content: Quote from: dferyance on September 24, 2019, 01:52:48 pmAt 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.

author: coppice
author_rank: Super Contributor
timestamp: September 25, 2019, 12:25:56 am
content: Quote from: Marco on September 25, 2019, 12:01:46 amThere 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.

author: james_s
author_rank: Super Contributor
timestamp: September 25, 2019, 01:34:00 am
content: Quote from: coppice on September 25, 2019, 12:25:56 amIt'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.

author: james_s
author_rank: Super Contributor
timestamp: September 25, 2019, 01:36:46 am
content: Quote from: coppice on September 24, 2019, 06:54:50 pmThe 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.

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: September 25, 2019, 03:13:39 am
content: Quote from: scatterandfocus on September 24, 2019, 05:12:53 amIf you are after high-quality LED lamps (bulbs), have a look at the the lamps made for the Californian market, with CRI at least 90 and R9 (red test colour sample score) of at least 50.Data sheets don't always list the R9 score, but the test results at energystar.gov show it, e.g.https://www.homedepot.com/p/Cree-40W-Equivalent-Bright-White-3000K-A19-Dimmable-Exceptional-Light-Quality-LED-Light-Bulb-2-Pack-TA19-04530MDFH25-12DE26-1-12/304473199https://www.energystar.gov/productfinder/product/certified-light-bulbs/details/2313947There 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

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 25, 2019, 04:59:08 pm
content: Quote from: thermistor-guy on September 25, 2019, 03:13:39 amDoes anyone manufacture bulbs using violet LED's and 3 phosphors?

author: Kilrah
author_rank: Unknown
timestamp: September 25, 2019, 05:16:52 pm
content: Quote from: Kjelt on September 24, 2019, 08:19:11 pmI 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.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 25, 2019, 08:38:37 pm
content: 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.

author: Kjelt
author_rank: Super Contributor
timestamp: September 25, 2019, 10:18:02 pm
content: You should never look directly in too bright light sources, be it incandescent, led, lasers or the sun.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 25, 2019, 10:29:22 pm
content: I started a new thread over here to hopefully get some experiences with higher quality LED lighting:https://www.eevblog.com/forum/reviews/workbench-lighting-211958/

author: james_s
author_rank: Super Contributor
timestamp: September 26, 2019, 12:19:24 am
content: Quote from: SiliconWizard on September 25, 2019, 08:38:37 pmYou 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.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 26, 2019, 03:21:56 am
content: Quote from: james_s on September 26, 2019, 12:19:24 amWe are both staring into LED's right now.

author: Sceptre
author_rank: Regular Contributor
timestamp: September 26, 2019, 03:25:38 am
content: Quote from: scatterandfocus on September 25, 2019, 04:59:08 pmThe technology is called TRI-R and was developed by Toshiba Materials:https://www.toshiba-tmat.co.jp/en/tri-r/about/index.htmlSeoul 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=sunlikeKnema offers modules with SunLike LEDs:https://www.knema.com/high-cri-for-the-best-color.htmlSome 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

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 26, 2019, 04:30:34 am
content: Quote from: Sceptre on September 26, 2019, 03:25:38 amThanks for that.I noticed this on Knema's site:Eye Safe High CRI SunLike LED LightingI have noticed lots of manufacturers involving LED's using similar terms in recent years such ashealthy, 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.

author: james_s
author_rank: Super Contributor
timestamp: September 26, 2019, 04:37:00 am
content: 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?

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 26, 2019, 05:02:14 am
content: Also, if previous and currently implemented LED tech is so safe, what is this all about?https://smartvisionlights.com/wp-content/uploads/pdf/IEC_62471_summary.pdf

author: Kilrah
author_rank: Unknown
timestamp: September 26, 2019, 08:18:34 am
content: The same as with any other light source, nothing's specific to LEDs in there.

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 26, 2019, 09:38:09 am
content: Pst kid, you want to see some confirmation bias?

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 26, 2019, 02:14:51 pm
content: Quote from: Kilrah on September 26, 2019, 08:18:34 amIt really is specific to LED's. It is in the title and the first sentence:QuoteQuoteI have a hard time imagining how anyone could think otherwise.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 26, 2019, 02:36:12 pm
content: Quote from: Mr. Scram on September 26, 2019, 09:38:09 amAdmittedly, 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.

author: Kilrah
author_rank: Unknown
timestamp: September 26, 2019, 04:20:43 pm
content: Quote from: scatterandfocus on September 26, 2019, 02:14:51 pmRead 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.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 26, 2019, 04:45:48 pm
content: Quote from: Kilrah on September 26, 2019, 04:20:43 pmIs there some place to download that whitepaper without a pay wall?

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 26, 2019, 06:36:21 pm
content: Quote from: scatterandfocus on September 26, 2019, 02:36:12 pmYou 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.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 26, 2019, 07:30:17 pm
content: Quote from: Mr. Scram on September 26, 2019, 06:36:21 pmMeh. I think my personal experiences go hand in hand with varous industries addressing the issues of LED. Every major eyeglass lens manufacturer is making blue-light blocking lenses. Every major monitor manufacturer is including blue-light reduction and flicker reduction technologies. Every operating system is including blue-light reduction software. Every major bulb manufacturer is making reduced blue-light reduced bulbs and flicker free bulbs. And on and on. And most of the industries are claiming to address eye-care issues, not sleep deprivation. I guess these industries also have 'confirmation bias', and goes right along with my own and so many other people.

author: Marco
author_rank: Super Contributor
timestamp: September 26, 2019, 08:58:22 pm
content: Flicker free bulbs were always available, the only thing which has changed is that all the shitty bulbs have now made it worth using it as a marketing bullet point.As for the rest, yes the public is by and large irrational and the manufacturers will respond to that rationally. Give the people what they want ... they want super warm high CRI light sources with lousy lm/W, the market will provide.

author: rrinker
author_rank: Super Contributor
timestamp: September 26, 2019, 09:17:14 pm
content: Most new(er) devices including desktop operating systems and displays themselves, have a "night mode" which reduces the blue portion of the spectrum. If I am alone in the office at work, I keep the lights off over m area, and use the night mode on my displays. I use the night mode on my handheld devices almost constantly - I'm not doing photo editing where I need accurate colors, I want the easiest on the eye setting. Seems to help. I never noticed the one effect of the bluish light keeping me from sleeping at night, but especially in a darkened room, the night mode causes less eyestrain. This is not the same issue as the UV leaking out, but a bright white/bluish LED backlighting I would say definitely causes more eye strain than a more reddish hue.

author: Kilrah
author_rank: Unknown
timestamp: September 26, 2019, 09:40:34 pm
content: Quote from: scatterandfocus on September 26, 2019, 07:30:17 pmThey go with what people will buy, which makes them money. Whether people buy for a valid or completely made up/placebo reason doesn't matter.

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 26, 2019, 11:17:33 pm
content: Quote from: scatterandfocus on September 26, 2019, 07:30:17 pmI appreciated how determined you are to dig the confirmation hole ever deeper.Blue light concerns are about our bodies taking cues from colour temperatures and blue light messing with sleeping patterns as it is recognised as daylight. If blue light causes your perceived issues regular daylight should trigger it too.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 27, 2019, 12:56:11 pm
content: Quote from: rrinker on September 26, 2019, 09:17:14 pmMost display manufacturers include a 'Reader' mode which shifts the color balance toward a warmer white.I think they aren't trying to put anyone to sleep while reading. But yes, most operating systems do call it something like 'Night' mode. But if you search for 'night mode' for any operating system, you will see most recommendations for using it mentioning preventing eye pain or eye strain. This isn't an issue that I just made up out of thin air. It is a very common and well discussed issue to do with computer displays since some years ago.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 27, 2019, 12:57:53 pm
content: Quote from: Mr. Scram on September 26, 2019, 11:17:33 pmYou sound like you want to argue with someone for the sake of arguing. Carry on I suppose.

author: fourtytwo42
author_rank: Super Contributor
timestamp: September 27, 2019, 06:11:14 pm
content: I think with regard to dodgy LED lighting the OP may be thinking of a regular poster on this and other fora who's posts often contain the phrase "OUR CONTRACTOR"Said posters subjects are nearly always related to an apparently dodgy company putting together dodgy LED lighting products based upon the advice of other members of various foraThese products are apparently LED streetlamps so I would definitely avoid being anywhere near them

author: james_s
author_rank: Super Contributor
timestamp: September 27, 2019, 06:17:21 pm
content: Did you come here seeking information or is this another one of those posts we see occasionally where someone comes in to spout some conspiracy theory or other nonsense veiled as a question about the topic?There is nothing dangerous or dodgy about LED lighting. Some is better than others, some can cause eye strain, but unless you are really trying by staring directly into a bright light source you're not going to actually damage your eyes. Blue light may well trigger your body to wake up when you should be preparing to sleep but that is not specific to LED.

author: Buriedcode
author_rank: Super Contributor
timestamp: September 27, 2019, 08:07:06 pm
content: Quote from: scatterandfocus on September 26, 2019, 07:30:17 pmYou must remember, the consumer industry doesn't always do things because there is good evidence for it. Cosmetics and dietary supplements are good examples here - it is what consumersthinkthey should do that drives the industry. Unfortunately these ideas are used as evidence that it is valid, so it becomes a circular argument. Banning a certain chemical from cosmetics, so advertisers can say "now without xyz" which leads people to assume its bad because - why else would they remove it?The blue light thing, as far as I'm aware came about because of three semi-related things.Firstly, as LEDs got brighter, the amount of blue light coming from the cheaper higher colour temperature dies became significant. This was mostly because of the brightness rather than the blue light itself, it is just unfiltered, there is a pretty strong blue line in white LED's, where-as the rest of the spectrum is spread out. Modern white LED's tend to have a much less pronounced peak here.Secondly, the discovery that we have cells in our eyes that seems to respond to blue light and are associated with circadian rhythms. This is why you often read about "screen time and disturbed sleep". I couldn't actually find any reasonable studies of this (please link if you found some) apart from news sites making claims. It has been assumed but not confirmed that it actually disrupts sleep, because the few studies I found used "screen time" (which involves web browsing, reading, interacting) or blue light (which isn't what screens emit) rather than just a blank white LED backlight. Here, someone has made the leap that blue light disrupts sleep -> white LED's emit blue light -> phone screens use white LED's as backlights (except the OLEDs!) -> ergo, phone = bad sleep.Thirdly, the relatively recent discovery that prolonged exposure to bright blue light can damage the eye. Again, it seems the media has assumed that "blue light" means "any white LED source, because they emit blue.. right?". It isn't really a fair test to expose retinal cells, in a dish, to strong blue single wavelength light, then assume that a phone screen will do the same to cells in the eye itself. But thats not what was originally claimed.I have no doubt that very bright LED sources can damage the eye, cause eye strain, and headaches. But so can all other light sources if the intensity is sufficient. I also don't know about the "blue light in white LED's affecting sleep" because I haven't found a reasonable study to actually test it.One tip for the OP - turn the brightness down. Most of the tablets, phones and laptops I've used over the past 10 years have become increasingly brighter on their default settings, significantly so. I recently set my phone brightness to 10% (Huawei TFT) and got used to it in about a day. At night, if I use it in low light levels I can get away with even lower that that. Also, "night mode" is handy on some browsers, since many websites still insist on having white backgrounds. If in doubt, don't change anything, and measure the light intensity yourself - then use those numbers for comparison when you reduce the brightness.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 28, 2019, 05:00:51 am
content: "Reduced blue light" is just marketing speak for "warm white".As for screen flicker, wouldn't there be more complaints back when 60Hz CRTs were the norm? Modern LCDs that flicker do so at 120Hz or more in order to reduce motion blur by hiding the times when the pixels are transitioning. (In 3D mode, that gets cut to 60Hz by the glasses which does flicker quite bad. Hence why 240Hz is a common target for high end 3D displays, giving a very acceptable 120Hz in 3D mode.)

author: james_s
author_rank: Super Contributor
timestamp: September 28, 2019, 05:30:04 am
content: CRT phosphors have a bit of persistence that helps but even so I could never tolerate 60Hz refresh, I always used 72-75Hz. LED backlights with PWM dimming often bother me much more.

author: Kilrah
author_rank: Unknown
timestamp: September 28, 2019, 10:10:39 am
content: Fluorescent lamps have flickered more than a decently designed LED lamp for decades and people were OK with that...

author: james_s
author_rank: Super Contributor
timestamp: September 28, 2019, 10:30:59 pm
content: Fluorescent phosphors also have some persistance, more so than LEDs so that could come into play. I was not bothered by fluorescent lamps and most LED lighting doesn't bother me but the stuff that flickers at line frequency does. It feels like a much more sharp strobing than the flicker of old iron ballast fluorescent lights.

author: coppice
author_rank: Super Contributor
timestamp: September 28, 2019, 10:46:01 pm
content: Quote from: james_s on September 28, 2019, 10:30:59 pmThe phosphors used in fluorescent tubes and LEDs have very little persistence. When either of these lamps is driven directly from the mains cycles, and you follow their light output through the mains cycles, they go pretty much down to zero output 100 or 120 times a second.

author: james_s
author_rank: Super Contributor
timestamp: September 28, 2019, 10:54:54 pm
content: Quote from: coppice on September 28, 2019, 10:46:01 pmPerhaps the LEDs go down to zero through a larger portion of the cycle? I don't know, I haven't actually measured. I just know that I can very much see the flicker on some LED bulbs while most others are just fine and don't visibly flicker at all. I've always bought one to evaluate first before buying more if I like the one I got.

author: coppice
author_rank: Super Contributor
timestamp: September 28, 2019, 11:03:01 pm
content: Quote from: james_s on September 28, 2019, 10:54:54 pmSome LED lamps are certainly off for a significant part of the cycle, as they won't turn on until the voltage has risen far from zero, so this may be a factor. Don't discount the effects of size. Most LED lamps have a much more intense output, as their radiating area is small. That intensity seems to affect how much a light source appears to pulse. Hopefully we will move away from screw in LEDs, towards structures with more space for better control electronics, and the flicker will go away.

author: maginnovision
author_rank: Super Contributor
timestamp: September 28, 2019, 11:21:36 pm
content: I'd love to have some LED sconces all in one units.

author: james_s
author_rank: Super Contributor
timestamp: September 28, 2019, 11:29:42 pm
content: They make them.I think that is the future of LED lighting, obviously retrofit lamps will be widely available for the foreseeable future but I'm confident that we will see more and more integrated light fixtures with no user replaceable parts. It will result in a lot of completely new light fixture designs that do not need to be built around the form factors of available lamps. Most of the lighting in newly built homes and commercial structures will be integrated LED designs rather than incandescent or fluorescent fixtures with LED lamps, it's already going that way.

author: coppice
author_rank: Super Contributor
timestamp: September 28, 2019, 11:45:09 pm
content: Quote from: maginnovision on September 28, 2019, 11:21:36 pmThere are a lot of these around, especially for designs introducing interesting form factors. Some are great, like large flat units for kitchen ceilings, that really spread the light out, and minimise shadows. The snag is they aren't designed to be user serviceable, and the parts don't follow standards, so they are hard to exchange. Hopefully this will change, but right now most failures require complete replacement, and a physically identical unit will probably not be available when you need one.

author: maginnovision
author_rank: Super Contributor
timestamp: September 29, 2019, 12:48:07 am
content: They're also fairly dim from my limited searching right now. In my office I use two sconces and each one has two 2500 lumen 5000K triglow led bulbs. Pretty sure none that I've seen will be able to light this room well enough. I'll have to keep looking.

author: Electro Detective
author_rank: Super Contributor
timestamp: September 29, 2019, 01:16:42 am
content: To avoid the possibility of copping a 'dodgy technology'financial hit,I'm sorta going old school and asap losing the 'previous dodgy technology' crappy circular fluoro light in the kitchen (dim, buzzing, hypnotic disco light, random RCD tripping POS)and getting a similar shaped fitting, that takes a pair of standard (buy anywhere/CHEAP) ES screw or BC bayonet LEDs in a warm white vibe, 10+ watts each,covered over with an aesthetics friendly oyster styled diffuser.A fitting like this I could care less about a 12 month replacement warranty offered with the latest integrated LED units that apparently 'last a long time..'which is hard to believe as they haven't been around a 'long time' yetMy choice above will 'last a long time' based on sheer simplicity, redundancy (2 LEDs), easy swap out, simple fault diagnosisand heaps cheaper to buy and a simple quick swap out for our local sparky to grab some cash on his/her way homeIf LEDs become dodgy technology, I can always chuck in a pair of 60 watt old school light globes, till the next 'technology' come along.I've already dumped those annoying squiggly and tubular shaped light saversand replaced with nicer LEDsLight fittings should be seen and not heard,or something like that

author: james_s
author_rank: Super Contributor
timestamp: September 29, 2019, 02:01:40 am
content: I did some quick tests tonight using a small PV cell connected to a scope and got some actual data, because engineers love data. This is not perfect, I was lazy so I didn't worry too much about ambient light but it remained constant throughout the test and was not a major contributor. I corrected for it in the first shot and then stopped doing that so for the generic integrated LED fixture use your imagination to add about a 1V DC offset.Anyway despite the flaws I still think this is interesting. Of the random light sources I had laying around the cheap integrated LED fixture is the only one that I noted to exhibit bothersome strobing and the resulting waveform illustrates why this is, the light output falls sharply to near zero where it spends a significant portion of each cycle before snapping on to nearly full brightness. Somewhere I have some LED filament bulbs that behave very similarly and I've seen a lot of low cost domestic LED fixtures that do the same. It is unusual in that the driver it uses is linear, there are no reactive components. The fluorescent lamp which is an older tube with a halophosphate type daylight phosphor on a simple choke ballast has nice smooth 120Hz bumps in the light output but doesn't fall to anywhere near zero between cycles. The other lamps have a bit of either 120Hz or high frequency ripple but no visible flicker. The amplitude was low enough that the frequency measurement on the scope can't really be trusted and I didn't feel like fussing around to capture that since it has no visible effect that I can see anyway.I can further investigate the properties of any of these various sources later if anyone is interested.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 30, 2019, 12:17:14 am
content: Well it is good to see that at least some discussion happened.How I see it, the reason why LED's end up causing eye strain and eye fatigue (especially in displays) is that they have a strong blue component (even edging on ultraviolet)l, intensity of the overall light, and PWM dimming. People who don't understand this often say that turning down the brightness of a display should be good enough. Well, it really isn't. One reason that merely turning down the brightness doesn't often work is because displays use PWM dimming, which tires the eyes. At full brightness, a PWM dimmed display can actually be easier on the eyes, especially if it isn't a very bright display to begin with, because at full brightness the backlight is steady. But manufacturers were in a race for ever brighter displays (and still are to some degree), neverminding the negative effects of PWM when these super bright displays are dimmed. As someone mentioned above, CRT's did flicker at low frequencies, but there was also a smoothing effect involved, rather than a sharp-edged off/on flicker. LED's respond very fast, and so the effects of PWM can be much harder on the eyes. Manufacturers have been addressing this by pushing the PWM frequency far up and calling their monitors flicker-free. Well, at least we don't see the flicker, but some of us can still feel the uncomfortable effects of it. And combine that with the strong blue component of LED displays, and it's not a good situation for eye comfort and eye health. Blue light having a shorter wave length than the rest of the visible spectrum is more easily able to penetrate the eyes. This isn't the same situation with sunlight because there isn't a huge dip just below the blue spectrum with sunlight as there is with LED, and the top of the red spectrum isn't suddenly chopped off as it is with LED light. Also, LED and other natural light aren't nearly as diffused as natural light, and LED in particular can have a hard glare to it, along with the heavy blue component and along with the PWM. Also, the strong blue light spectrum is very much analogous to listening to loud high frequencies. And PWM dimming is very analogous to listening to square waves, where there is a high frequency switching taking place that is in addition to the high frequency blue light spectrum. Neither are a pleasant experience, for the eyes or the ears. Oddly, some people seem less bothered by it all.Something that I have found in my experience of trying to continue to use computers regularly since LED backlighting became the norm is that VA panels are actually somewhat easier on the eyes than other display types. It isn't perfect, but it is more comfortable. I think this has to do with VA panels being capable of blocking more of the backlight (VA panels typically have much greater contrast) and VA panel pixels having significantly slower response times that TN, IPS, or OLED, which may be smoothing the on/off switching of the LED backlight.Any way, whether anyone here agrees with it or not, some people (aye!) have been permanently affected by LED backlighting, for whatever reasons. And once that happens, our eyes become more sensitive to LED lighting in general. It's a repetitive stress injury, the same as any other, where the eyes have been worked too hard. Getting away from LED lighting altogether definitely does help, but in the long run it is impractical. There is no conspiracy here. I'm here to discuss electronics issues the same as anyone else. I have no motives other than learning from and adding to the collective wisdom of members of a forum, the same as any other forum.

author: Electro Detective
author_rank: Super Contributor
timestamp: September 30, 2019, 10:21:23 am
content: No contest to the above OP commentThat said, if you want products that are 'easier' on the eyes, you have to shop around and try what's on offer till you hit on a goodie,and don't lose those purchase receiptsNot all LED lights, monitors, plasma displays, CRT products etc are equal in quality or how one's eyes perceive the imagesi.e. been there already

author: Buriedcode
author_rank: Super Contributor
timestamp: September 30, 2019, 12:53:48 pm
content: So, wait, you're saying your eyes started having problems since LED lighting was introduced in.. monitors? Or as general lighting? How do you know this isn't co-incidental, related to age, or perhaps you need a new prescription for your glasses? Or of course, the fact almost everything is brighter these days? As several have mentioned in this thread, when trying to work out something as subjective as eye discomfort, it is important to to no jump to conclusions such as "it must be PWM" without confirming that the source of the discomfort is actually using PWM. Or claiming that there's significant UV emitted, without testing the source?You seem to have bundled together the "Strong emission of blue light" which is likely no more than CCFL sources, and relatively low frequency PWM dimming. Again, no-one is disputing that strong blue light, or low frequency PWM dimming can't negatively affect the eye, but you're assuming that these two things are related and common, without anything to back it up.I think almost everyone in this thread has seem the "flicker" or low frequency PWM's LED's, especially when turning ones gaze quickly, or in the case of car brake lights (which must be at 200Hz or something stupid). But I haven't seen this is display backlights. I'm sure they must use PWM, but I'll have to measure the frequency.Sorry to keep banging on with the same themes, but you seem to have skipped over what others have said and just re-stated that you think its all "blue light and PWM". Also..Quote from: scatterandfocus on September 30, 2019, 12:17:14 amWho? And how does it make the eye more sensitive to LED lighting?

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 30, 2019, 01:47:17 pm
content: Lumping together blue light and flicker even after you're told they're two very different things screams having heard a thing that one time and attaching all kinds of far reaching conclusions to it. Move along, nothing to see here except proof that the scientific method is key to end up with something other than cargo cult nonsense.

author: Kjelt
author_rank: Super Contributor
timestamp: September 30, 2019, 08:24:36 pm
content: This kindof things always occur with the introduction of new tech.I remember a discussion twenty years ago about the electronic fluorescent energy saving bulbs.There were people that really accused the bulb manufacturers of including mind psyche influencing electronics into the bulb that manipulated the people so they would be more compliant to government

author: Electro Detective
author_rank: Super Contributor
timestamp: September 30, 2019, 10:40:52 pm
content: Those electronic fluorescent energy saving bulbs were and still are sub standard lighting, hard on the eyes, tiring to work under,did the manufacturers evaluate a few in their mansions first, before shipping the eyesoreware out to retailers to flog to the connedsumers?They are apparently not land fill friendly either, which means they will appear in animal/peoples food and drink sometime in the futureThe latest LEDs are miles better in all respects, especially if you can no longer afford the superior halogen lighting bills

author: james_s
author_rank: Super Contributor
timestamp: September 30, 2019, 11:55:59 pm
content: I replaced almost all of my incandescent lamps with CFL in the late 90s and they seemed fine to me. LED is certainly superior though even just for the instant on and not minding short cycles.

author: coppice
author_rank: Super Contributor
timestamp: October 01, 2019, 12:53:16 am
content: Quote from: Electro Detective on September 30, 2019, 10:40:52 pmElectronic fluorescent energy saving bulbs are not just one thing. There are ones with bizarre colour rendering, and ones with very good colour rendering. There are ones that pulse at 100Hz/120Hz. and ones that operate from DC, with electronic handling of the negative resistance.

author: Electro Detective
author_rank: Super Contributor
timestamp: October 01, 2019, 10:00:17 am
content: All the ones I've come across over the years are poor quality light, be they blue-ish or yellow-ish light,high or low output = bad news for the eyes and attention span all roundSit and work under those for a few hours,and then compare with LEDs or halogen the next day, for twice as long a period, and you'll ditch all the electronic fluorescent energy saving bulbs in a heartbeat.I haven't done the bench homework yet for power draw, but strongly suspect LEDs are not too far off the 'energy saving' deal of fluorescents

author: Kjelt
author_rank: Super Contributor
timestamp: October 01, 2019, 10:20:58 am
content: LEDs are nowadays more energy efficient than fluorescent.The bad rap comes from cheap drivers (in both cases). For professional lighting a driver contains many components, BOM over $12 a piece, that is good led driver.The rest is asking for compromises, low lifetime, flicker due to PWM <1MHz with dimming or PWM <500Hz without dimming, etc. etc.When the world changed from incandescent to LED the thing to aim for was a change of fixtures, so fixtures that had leds integrated but also a good qualiy driver.However as it turns out consumers want the cheapest solutions, the fixtures and even the old fashioned E27 lampholder they were accustomed to over the years.The whole consumption society changed from good quality to cheap replace within 4 years, so yeah you get what you pay for.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: October 01, 2019, 03:35:36 pm
content: Quote from: Buriedcode on September 30, 2019, 12:53:48 pmQuote from: Mr. Scram on September 30, 2019, 01:47:17 pmFor computer displays, I have tinkered around with PWM frequencies and blue light reduction through software. I'm not lumping them together. It is being assumed that I am lumping them together to carry an argument. Arguments based on assumptions don't make for constructive discussion. Rather, they make for guaranteed back and forth bickering. Where something isn't clear, it is always better to ask questions rather than to cast arguments based on personal assumptions. Let's keep it civil and constructive.What I have found in my admittedly limited tinkering is that for altering PWM frequencies using software (which definitely has major limitations), there isn't any major difference to my eyes once the PWM frequency is high enough not to see visible flickering (PWM lines). With visible flickering, a display is terrible on my eyes, but upping the frequency to get out of that range isn't that much more comfortable, dependent on individual displays. I suspect here that altering PWM brightness through software is much too limited in the frequency range. And the issue is probably as much to do with the shape of the dimming waveform as the frequency, or at least it is likely a factor. There are also the issues of polarization and diffusion. And on altering overall color balance, I have found that moving toward a warmer overall color (more yellow) can be very helpful, but it also depends on what else the individual display is doing overall. It is very touchy stuff dialing in a display for long term use, to my eyes. And some displays are just unusable no matter what. At this point, not knowing alot about what is going on in displays electronically and optically, I am very interested in finding out more. And it is one of my motivations in learning electronics. This year I bought some displays of different types (IPS, TN, VA) and experimented with them to find out what I could (within my technical limitations) and compared them to other displays that I already have. One other issue that came up during that was the sharpness of text on a display, in addition to the PWM, blue light, and other issues mentioned above. Going to measures for sharpening text, such as turning off anti-aliasing, can be very helpful. And higher resolution (4K) can be very helpful. But all of the issues are part of a bigger picture, where addressing any one of them alone is not a magic bullet for eye fatigue.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: October 01, 2019, 03:41:36 pm
content: Quote from: Electro Detective on September 30, 2019, 10:40:52 pmIt seems to me that if some technology is physically uncomfortable, it would be good to know why it is the case. The general mindset around lighting and displays today seems to buy to just buy more until we find something that is least uncomfortable, neverminding finding out something about why. It would be a very good thing have some electronics knowledgeable people hacking on lighting and displays, toward the goal of better eye comfort.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: October 01, 2019, 03:45:54 pm
content: Quote from: coppice on October 01, 2019, 12:53:16 amQuote from: Kjelt on October 01, 2019, 10:20:58 amHow does a person buying lighting products today make a distinction between these aspects of fluorescent and LED lighting? What should a person be looking for specifically?

author: Kjelt
author_rank: Super Contributor
timestamp: October 01, 2019, 04:08:32 pm
content: Best you can do is buy the quality dimmable drivers yourself ($30-$75 each)To be honest buying led bulbs you buy the low cost stuff where everything was cost down.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: October 01, 2019, 05:57:44 pm
content: Quote from: Kjelt on October 01, 2019, 04:08:32 pmAny recommendations for a DC supply and dimmer?

author: scatterandfocus
author_rank: Regular Contributor
timestamp: October 01, 2019, 07:09:08 pm
content: I also wonder what might be any complications in adding DC power and dimming to a computer monitor.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 01, 2019, 07:30:59 pm
content: "Arguments based on assumptions don't make for constructive discussion."Glad you're finally coming to that realisation. Time to shutter the thread?

author: Gyro
author_rank: Super Contributor
timestamp: October 01, 2019, 07:58:15 pm
content: Quote from: scatterandfocus on October 01, 2019, 03:35:36 pmWait, you can't alter the LED PWM frequency in software, that's a hardware function of the LED driver chip. Youcanalter the LCD refresh rate in s/w but not the backlight PWM frequency.Altering the backlight brightness will change the LED PWMduty cyclebut not the frequency.Blue light reduction, likewise, is a change to the colour palette and/or contrast of the LCD, not the backlight colour.

author: james_s
author_rank: Super Contributor
timestamp: October 01, 2019, 11:52:23 pm
content: Seems like I read that there are some laptops that do allow the PWM frequency to be configured in software but I don't recall the details. In my case it was some new desktop monitors they got at a former job that had terrible PWM flicker. The laptops I have now both at home and at work are LED backlit and don't bother me a bit so YMMV.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: October 02, 2019, 05:27:58 am
content: Quote from: Gyro on October 01, 2019, 07:58:15 pmI don't know if you are a Linux user or not, but there are commandline tools for adjusting PWM on Linux. Maybe there is something out there for Windows and Mac OS too. See for example:https://aur.archlinux.org/packages/intelpwm-udevThe backlight has to go through the panel, so adjusting color of the display definitely does have an effect. You can see this most noticeably by displaying a white page and adjusting colors, but it is very obvious even on a black page. The backlight will always bleed through to some degree, even with VA panels which have considerably higher contrast ratio than IPS and TN panels. Anyway, most displays that I have seen are way too blue by default. I see blue screens everywhere I go. Computers, tv's, information screens, cash register displays, and on and on. Once you see it you can't unsee it.I remember well over a decade now, blue LED indicators were trending in audio gear. Many users complained of the harsh and glaring light, and manufacturers stopped using them. They looked aesthetically nice initially, but they weren't so nice to the eyes. A very common thing for gear using blue LED's was to cover them with black electrical tape. Oddly, a single blue LED on a piece of audio gear was unacceptable to many buyers of audio gear. But still today, blue LED's are used as the main backlighting for most displays, even though many users have eye discomfort from them. Having a loud high frequency peak in audio wouldn't be acceptable by anyone for audio gear. It would be deemed as uncomfortable to listen to. But we have the optical equivalent in LED lighting with a strong blue band dominating the light output, especially with computer displays. That is why manufacturers have turned to more yellow and dimmer LED lights. And I agree with anyone who says that the yellow'ish LED lights aren't so great. But it seems to be one way or the other so far with LED lighting. If this were audio we are talking about, the yellowing would be the equivalent of rolling off the highest frequencies so that we are only hearing the midrange. It wouldn't be as uncomfortable to listen to as with a strong high frequency peak, but it also isn't good quality audio, the same as heavily yellowed blue LED's isn't good quality light.

author: ebastler
author_rank: Super Contributor
timestamp: October 02, 2019, 06:11:27 am
content: Quote from: scatterandfocus on October 02, 2019, 05:27:58 amPersonally I don't notice a problem with the various LCD monitors I use. But it seems that it's not too uncommon for users to perceive eye strain from the blue light. My optician offers glasses with a blue filter which are specifically targeted at computer users. The tint is supposedly subtle enough to not get in the way during other activities (and many people use a dedicated pair of glasses for the medium-distance viewing of computer screens anyway). Maybe worth a try for you if you are sensitive to the blue component in the spectrum?

author: Buriedcode
author_rank: Super Contributor
timestamp: October 02, 2019, 02:17:05 pm
content: Quote from: scatterandfocus on October 02, 2019, 05:27:58 amThat appears to be for laptops. This makes sense as laptops have aggressive power saving schemes so will adjust the backlight dynamically (like tablets and phones). It will do nothing for external desktop monitors. I was under the impression you were complaining about all displays.Quote from: scatterandfocus on October 02, 2019, 05:27:58 amWhat exactly are you talking about here? Are we still talking about the PWM "flicker" of the backlight? Or the amount of blue light a display emits? Or is it that the "flicker" seems to affect you more depending on the colour of the display? A black page will hardly emit any light. Unless the display is very old, contrast ratios of 1000:1 are pretty common, which is achieved not only by having much brighter displays (because of more efficient LED's and lightpipes) but also better polarisers. If you notice "flicker" when the display is off (but the backlight on), your monitor is either faulty or very old.Quote from: scatterandfocus on October 02, 2019, 05:27:58 amAgain, are you talking about the colour temperature of the displays? I rarely see "blue" displays anymore, since it was never a good background colour. Just because something looks like its "cool white" (which by definition has more blue in it than warm white) doesn't necessarily mean it actually hassignificantlymore blue in it, or that its blue line is a sharp peak. As I mentioned before, displays are much brighter these days. Not only that, but your perception changes based on what you're used to. If you have "warm white" lighting everywhere, then cool white lighting or displays seem much harsher.Quote from: scatterandfocus on October 02, 2019, 05:27:58 amYes the blue LED craze was awful. They eyes have trouble focusing on it so it was often blury and glaring. Thank god they banned them on the front of trucks (at least in the UK). But this isn't the same as talking about white LED backlights. White LEDs have a much less pronounced blue peak, and they are not point sources - lighting uses point sources, but a great deal of engineering has gone into making lightpipes that convert point sources into even panels.. I'm not sure why you're comparing bright blue LEDs to white LEDs.Quote from: scatterandfocus on October 02, 2019, 05:27:58 amThe audio analogy isn't that great, because if we hear a source with a loud frequency component, our ears "EQ" that to be flatter, so if we listen to bass-heavy music, then "normal" music will sound quite tinny afterwards. Our eyes (well, brains) DO adjust colour perception, but not quite in the same way. You seem to think we become more "sensitive" to it, when in reality its the opposite, our brain will adjust to it to reduce it. Also, as soon as audio gets mentioned in a discussion it goes into the realm of subjective preference and the whole value pseudoscience that inevitably followsQuote from: scatterandfocus on October 02, 2019, 05:27:58 amSo, how do you know that ALL the white LED backlights you've seen have a strong blue line in them? I'm not claiming you don't have problems with glaring displays, just that you are doing a lot of hand waving to convince yourself and others that its all about LED's emitting lots of blue light, and the flicker from displays, when there are many MANY things that can contribute/cause eye problems.I'm not sure you're going to convince many people that LED backlights, or LED lighting is worse quality without something to back it up. Measurements, part numbers of devices/displays/bulbs, spectra (which admittedly, isn't easy to get!), scope captures of the PWM if displays etc..

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 02, 2019, 02:21:47 pm
content: Quote from: ebastler on October 02, 2019, 06:11:27 amI personally don't know. It's really hard to tell actually, short of doing experiments with and without filters, and see if it makes any real difference for a particular person in the long run.I would tend to think that the external lighting of the room you're in is more important than whatever your monitor emits. So that, unless you work in very low light condition, I'm not sure it makes a big difference. But that's just an opinion and experience, not a fact.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 02, 2019, 03:20:02 pm
content: Quote from: ebastler on October 02, 2019, 06:11:27 amAgain eye strain isn't the issue with blue light. Disruption of the circadian rhythm is as it mimics daylight to a degree your body can respond to it.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: October 02, 2019, 03:54:19 pm
content: Quote from: SiliconWizard on October 02, 2019, 02:21:47 pmAmbient light definitely is a big factor for me. Most of my computer use these days tends to be outside on a shaded porch with a laptop. And it definitely does help for eye comfort in comparison to indoors. My hunch as to why is that the color spectrum from the LED backlit display is being balanced out to some degree by the natural ambient light. I intuit this from experience in mixing audio. In an audio mix, is is desirable to have a balanced frequency spectrum with no major peaks or dips that make the overall audio sound odd or uncomfortable to listen to. If you take a 'peaky' audio source and mix it in with a fuller spectrum audio source, it can be much more acceptable to listen to.And what I have seen in spectrum graphs of 'white' LED's (blue LED's with phosphor coatings) is that they tend to either have a too high blue peak (cool LED light) followed by a big dip, or a too low blue peak (warm LED light).For some very expensive LED backlit displays (I have an old one here), the backlight uses red, green, and blue LED's in order to provide better control over the light spectrum. But using an RGB backlight is considerably more expensive than using a so-called 'white' LED backlight (blue LED with phosphors coating), which is why they aren't more widely used in computer displays. RGB backlighting more directly addresses the issue of achieving a full light spectrum at the source of the problem, where 'white' LED backlighting attempts to address the issue after the fact. Using phosphor coatings for achieving 'white' LED light seems to me to be a lot like using psychoacoustic effects to create the perception of audio frequencies which aren't really present. See for example:https://en.wikipedia.org/wiki/Psychoacoustics#Missing_fundamentalIt isn't exactly analogous to how 'white' light is being achieved using blue LED's, but if you look at a datasheet for a blue LED (for example:https://www.mouser.com/datasheet/2/427/tlhb44k2m1-1315895.pdf) you will see that there is huge blue peak between 400-450nm which is being optically filtered to achieve a fuller light color spectrum for a 'white' LED. It does seem very analogous to filtering an audio tweeter (by whatever means) to try and achieve a full range sound. And it isn't a high quality means for achieving a full spectrum of light anymore than filtering a tweeter is a high quality means for achieving a full spectrum of audio. In audio, we try to achieve the closest representation of the final sound at the source and use filtering after the fact for minor adjustments, because using filtering causes undesirable phase issues around the bands which are being altered. But with 'white' LED light (blue LED with phosphor coating), filtering is being used as the primary means for achieving a final spectrum of light from a low spectrum source. That seems very backward and shoddy to me. But it is cheap.To try and more clearly illustrate what I am saying here, consider this: If we begin with a 3-way speaker which has individual drivers for bass, midrange, and treble, we can get a good full spectrum of sound, which requires some filtering to better balance what is coming out of the speaker (crossovers and eq). If we instead switch off the bass and midrange drivers and only use the tweeter, using heavy filtering as the primary means for trying to achieve a full range speaker sound, the result will be poor. But that is the situation for achieving 'white' light using a blue LED. We don't have a bass driver (red LED) or a midrange driver (green LED) to work with, so we are using heavy eq (phosphors) to achieve something toward a full range sound. One problem with doing that is that the higher frequencies are going to be most dominant and the low frequencies largely missing (even after extreme filtering). We can further filter away the highest frequencies, but the overall spectrum is still going to be much more narrow than when using all the drivers in a 3-way speaker. And the overall volume (output intensity) is going to be much lower than when using a 3-way speaker, requiring using multiple tweeters (blue LED's) to achieve the desirable volume. And further, there is gong to be major phasing issues across the spectrum. So then it seems to me that the situation for using 'white' LED's is very much like using say, a single driver laptop speaker, instead of a proper 3-way speaker. The 3-way speaker is going to much better give a fuller spectrum, higher volume of that fuller spectrum, and much less phase issues than when using a single small driver to achieve a full spectrum.Apologies for the many edits.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 02, 2019, 10:08:47 pm
content: Yeah, to sum it up a bit, ambient light is a big factor here when using displays in general.And yes, white LEDs tends to have a spectrum that's closer to sunlight (except for the UVs, apparently most LEDs emit very little, or almost no UV at all) than your typical incandescent bulb, so yes it can cause issues to the circadian rhythm at night time.Humans beings are not the sole "victims" of this. At places they put outdoors public LED lighting, you can notice that birds can get bonkers and start singing in the middle of the night. I've noticed it in my area. Sure the spectrum is not the only problem; brightness is often way too high.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: October 03, 2019, 05:13:30 am
content: I haven't had any sleep issues from using LED backlit displays or LED lighting. Maybe some people do, but I never heard of it in person happening to anyone. I have asked around at work before to find out who gets eye discomfort from computer displays (all the displays at work are LED). Literally everyone I asked said that they either get bothering discomfort or eye pain from working with them, but maybe it would have been the same for CRT's or CFL backlit displays. And a couple of people told me that they are bothered by the fluorescent lights, too. The fluorescent lights at work do bother my eyes some, but not nearly as much as using LED backlit displays.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: October 03, 2019, 06:28:35 am
content: A few links on the topic at hand:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3948029/https://www.ama-assn.org/press-center/press-releases/ama-adopts-guidance-reduce-harm-high-intensity-street-lightshttps://www.anses.fr/fr/node/79974