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Comment by tigershark | Hacker News Reader

Why would you use an e-ink display for videos? The main advantage is the low power consumption because it needs power only to refresh, using it for a video it will negate that advantage and draw much more power than a traditional display with an awful image quality...

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Not the OP, but the main reason I want an e-ink display (for programming, which may include animations) is so that I can do it in full sunlight. I work remotely and often work in public places. Working on a park bench, for example, is normally impossible, unless it happens to be cloudy and I'm in a shady place. I'm just hoping e-ink becomes a mainstream thing before I retire.

The new MacBook Pro screen work in full sunlight - it's just about being bright enough.

Another option is to place the back of a plastic screen towards the sun, using it as a backlight.

Have you seen an e-ink display?

It is about contrast, not brightness.

You need brightness too. I have both e-ink and MBP screens - both work in the sun.

Just to give some numbers:

e-ink has a contrast ratio of about 20:1 with 40% reflectance. A sunny day is 10000 - 30000 nits, giving at least 4000 nits of brightness.

The 2018 MPB screen has a 1500:1 contrast ratio and about 500 nits of brightness.

So if e-ink is really easier to read in the sun (which I think) then brightness is much more important.

It's not that simple. I cannot explain the physics/physiology of it with any authority, but as someone who suffers from severe strain and headaches with LED (and some CCFL) backlighting I can you it's feeling like something to do with direct vs reflected lighting vs some brightness or contrast metric. Looking at E-Ink or print on paper in a variety if lighting is generally fine (as long as it's bright enough for a normal person to read..obv too dark and different strain occurs)...but an LED backlit LCD even on low settings (so maybe 10% of those 500 nits) results in problems. Stare at a lightbulb vs staring at a white wall that bulb is shining on for a simple illustration. I don't believe it's polarisation either since wearing polarized sunglasses doesn't result in strain and just like an LCD polarizes the light that reaches your eyes, so do the glasses.

That's a very power-intensive way of doing it. Sunlight is about 120 watts per square meter[0]. My 14-inch laptop (a Thinkpad T430) display has an area of 0.0543 square meters, so in full sunlight it is illuminated by 6.5 watts of light.

White LEDs are currently approximately 25% efficient (and have a limit of 44%)[1], so my LCD display needs to use 26 watts of electricity to be as bright as direct sunlight landing on it.

My laptop's backlight can't actually do that, but if it could, it would exhaust 70 watt-hour battery in less than 3 hours, without accounting for any power used by the CPU, network card, RAM, or hard drive.

[0] https://en.wikipedia.org/wiki/Sunlight

[1] https://en.wikipedia.org/wiki/Luminous_efficacy#Examples_2

1. Currently, I use it for writing code and reading papers. However, I still want the monitor to be a good enough drop-in monitor for things I need to occasionally do. For example, I need to switch to a browser window to check what was that error I'm getting.

2. Visual snow syndrome: Many had their first experience of visual snow after staring into the screen for too long. People who believe in that is the cause of visual snow would want a screen that does not emit light.

How well does it fare for those tasks (code and papers)? I'd very much like to have such a screen but the price tags of what I've seen so far is probihitive…

What exactly about emitted light is a problem? Light doesn't carry a memory of how it was generated, so it must be some difference in some measurable property, e.g. brightness/contrast/color spectrum/flicker/polarization, or the way these change at different viewing angles. If you know which attributes are important then you might be able to match them with an emissive display.

Emissive displays don’t generally match the brightness of their surroundings; even with automatic adjustment, most are physically incapable of being as bright as a newspaper in daylight, and many cannot be as dim as a newspaper lit only by one of those small book-reading lights without being switched off entirely.

There’s also the spikey spectrum, which looks the same consciously but I’ve seen claims [1] that is messes with our circadian rhythm.

[1] I lack the skill to tell if this is real science or neo-mystic woo.

I found this command that works, so far, on all my Linux laptops, to give much greater control over backlight intensity.

  sudo su -c "echo 200 >/sys/class/backlight/intel_backlight/brightness"

Replace 200 with another number for different brightness.

Haven't found a Windows nor MacOS equivalent though.

I've used it a fair bit in conjunction with Redshift to get a screen that's reasonable for reading ebooks in low light.

I'd buy an e-ink laptop tomorrow if there was one.

>Emissive displays don’t generally match the brightness of their surroundings

How so? You can set any brightness you want to match the environment. Usage under direct sunlight is one edge case e-paper is clearly better at, and any usage with poor environmental lighting is detrimental to your eyes itself, regardless of technology.

I'm really sceptical about the entire "E Ink is better for your eyes" thing until I see some serious studies. People managed to ruin their eyesight centuries before computer screens. There's just too many factors at play here, from genetics to typography.

It’s not that they don’t auto adjust. It’s that they’re physically incapable of the range of light intensity we encounter in a normal day. For example, full afternoon sunlight is something like 150,000 lux, but normal house lighting is ~200(in a good scenario as high as 500-1000). The same is true on the other end of the scale.

I think most people are forgetting that LED backlights are controlled usually using PWM which flickers, fast, but still flickers. I haven't found any research about how it might affect humans. I suspect it would be better if no-flicker current-controlled LED backlight was used instead of PWM.

According to notebookcheck only about half the devices they tested use PWM:

https://www.notebookcheck.net/Why-Pulse-Width-Modulation-PWM...

It seems to be well known that it for low frequency PWM it causes headaches for some people, so I would expect that there is at least some research in that direction. That said, it seems to only be a problem for few people and only for very low frequencies.

Staring directly at a light source strains the eyes more than watching reflected light.

By what mechanism of action? It can't possibly be true in general: e.g. staring at the reflection of the sun in a mirror strains the eyes more than staring at a candle.

A reflection of the sun on a mirror is a reflection of a very strong light source through a perfectly reflective medium.. A book or an e-ink screen is still ultimately sunlight, but it has scattered (which is reflection too) while passing through the atmosphere many times before reaching what you are looking at.

Could this be some unknown effect of polarized light vs. non-polarized?

So it's a question of total light intensity, not of being reflected or "direct" (whatever that means).

I don't think so myself because I don't have pain in full sunlight reading print or E-Ink which is much brighter "nits" than an LED backlight produces ....but even low settings on an LED backlit computer hurt. There is in my opinion a difference between looking into a light source and looking at things that are visible due to reflected light like E-Ink, paper, the objects around us even if I cannot quantify it with scientific explanation.

This makes no sense to me. There is only one kind of light and it has just so many parameters: basically, the distribution of intensities along the spectrum. If reflected and emitted light have the same intensities there is no physical way to distinguish them.

Ok. Regardless of the intuition, staring into a light source feels different to everyone I have ever known that staring at normal objects reflecting light, like paper etc. Someone above claimed that reflected daylight was a lot more nits than a laptop could put out so I was going with the idea that this is true. I can look at paper in bright daylight with no eye strain. I cannot look at most LCDs even at low brightness without bad eye strain. It's not PWM in my case as I have ruled that out. Its much worse on LED displays. Fact remains that staring at backlit stuff gives people eye strain in ways printed or reflective never does and it seems logical that staring at the direct light source is a part of this.

I know its not scientifically measuring nits/lumens etc but stare into even a low wattage (15w etc) light bulb for a few min and see how it leaves you feeling...seeing spots etc. Then stare at a newspaper or book or E-Reader under a 250w lightbulb or even brighter sunlight outside...and notice how you do NOT have that same problem. Even with a much brighter light source there is something different about how/how much actually enters your eye. I'd love an answer as this is a major life problem for me.

I think the difference may be in the contrast between the letters. A printed paper under the sun is very bright, but the black letters absorb most of the light and they are very dark and easy to tell apart. For a bright computer monitor, both the black and the white pixels are very bright, forcing the eye to strain itself to distinguish between two very bright intensities, which is difficult. Does it add up?

I am sure contrast is a variable but overall this still doesn't seem to solve the issue for me. A faint grey pencil on paper is not straining, but even the best contrast displays like OLED are very straining. It's literally again the light shining at you and the entire thing you are looking at being a light source that I believe is the problem. I don't see sparkles or glows or any of those sorts of things looking at printed text or reflective tech...but I do see it when an LCD display is backlit. Even the blackest black on an LCD, on a white background, has an illuminated feel vs a printed/flat feel. The only time reflective tech/paper bothers me is if there isn't enough light to see normally as with anyone. LCD's, esp most LED ones, it's nearly all the time.

If I look at a matte LCD display (glossy doesn't work in this example due to reflection) in bright sunlight there is a narrow window of display brightness where the things are bright enough to be readable but the sunlight overwhelms the "lit" effect and it appears sort of like you would expect color E-ink too...more flat and printed like the display is now reflective rather than backlit..but it's a very narrow sweet spot that's hard to maintain and I cannot seem to replicate well with artificial lighting inside as it takes a lot more than a 60w bulb even directed right at the display and glare starts to become a factor with a more concentrated light source vs ambient, indirect light from outside. Brightness too low and it's unreadable due to contrast, too high and you get the glow again. To me the root problem is the backlighting somehow...possible combined with dithering or other rendering games that cause even static images to be moving as far as the eye is concerned. But it's not a common enough issue for industry to care about, and as with most things, until individuals suffer from something themselves, they often refuse to believe it's an issue for others.

If I had to guess it is probably a few things.

Firstly staring directly at a light source means that you are seeing most the rays directly. The only attenuation you will receive will be scattering from the medium - presumably air which will be low.

Seeing it from a second surface adds more effects - the surface may have absorb some of the light. Any real surface is also not going to have perfect reflectivity (everything from scattering, internal diffraction and destructive interference could occur). In short there will be loads of secondary/tertiary effects causing attenuation. Someone also mentioned polarisation, I also wonder about interaction between reflective surfaces which could cause additional attenuation via interference but the physics of waves has never been a strong point.

The other major factor is the physiology of the eye - we evolved from a world that didn't have abundant light sources and it's hard to know the effect of focusing on a source of light that differs from the ambient profile.

I was under the impression that Visual Snow was a symptop of anxiety?

anxiety is a symptom of an underlying nervous system dis-order. so staring at a screen for long periods of time is hard on an organisms nervous system (to remain in place for so long without movement). So visual snow and anxiety both stem from the underlying structure being at dis-ease.

Visual snow could also be to to flickering from PWM, or more likely temporal/spatial dithering (a leading theory in LED LCD based eyestrain but as yet unproven as the cause). Even a white background on a monitor, even a static image, isn't just static white...it's constant flickering of pixels to make a certain "white" and to smooth moving images as well. Whatever the ultimate cause it's not normal or healthy to stare at emitted light most of the day and most of us do...add flickering and other visual tricks displays use and it's no wonder eyestrain exists. Nobody would stare at a 300 nit lightbulb for hours and call that reasonable, but that's what backlit LCD displays are. I didn't have a problem for most of my life, and still don't with books under proper lighting, but now I have a severe one with LCDs that and cannot find a definitive answer or fix and frankly it's crushing a last chance I have to be somewhat independent and survive.

> I use it for writing code and reading papers.

Does it look good with white text on black background ?

It does not look good, and black causes ghosting.

Visual snow was a thing years before computer monitor existed.

> The main advantage is the low power consumption

No?

The main advantage is that it's easier on the eyes

People keep saying eInk is better than reflective black and white LCD, such as that found on calculators.

I’m unconvinced, but (obviously) to test this I would have to actually get a monitor sized black and white reflective display, and I can’t find any of those — largest I have found so far is 320x240 for about £200

I haven't seen a reflective black and white LCD matrix that didn't suck. Think TI-82 calculators.

That being said the segmented LCDs like those found in 4 function calculators and wrist watches usually look fantastic.

I had a TI-83. Yes, the resolution was terrible by modern standards. The contrast was fine until the batteries started to die.

If I didn’t already have way too much on my personal to-do list, I’d be interested in converting an LCD with a backlight into a reflective one. I assume it’s not possible with all models, but also that it is possible with some.

IMO you do not have to go that far for graphical reflective LCD that didn't suck: TI-89 has one. Also LCDs in Psion handhelds were quite reasonable.

I can't find my TI-89 to compare but I have a TI-85 and TI-83 from the late 90s and the newer 83 has a noticably better screen so you're probably right. I recall being impressed by the TI-92's screen but I sold mine long ago so I have no basis for comparison.

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