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Chemists discover how blue light speeds blindness

phys.org

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Re: Chemists discover how blue light speeds blindness

#271

Post by ScottBurson »

Really surprised there's no discussion here about the ubiquitousness of black-on-bright-white color schemes in apps (including this text box I'm typing into right now, though for the most part, HN uses a soft beige tint for its background; but it's still dark-on-light). It's really quite unnecessary. For code editing I have a light-on-dark Emacs color scheme, which is much easier on the eyes.

Yes, Macs have a setting to invert the color palette, but that's not useful to me — a lot of my windows are dark; I don't want them inverted, and it makes images unintelligible. What I really want is something that doesn't screw with images, but detects dark-on-light text and maps the colors in such a way as to preserve contrast and even hue.

Re: Chemists discover how blue light speeds blindness

#272

Post by abledon »

copperx wrote: post #242
wpasc wrote: post #156

Earlier quoted context omitted.

Thank you for your input, but I mostly want to thank you for f.lux. It has been one of my favorite things for a long time. It's silly how long it's taken companies to provide a native blue light filter and your product just kicks ass. If you guys ever wanted to figure out your app on a smart TV (or apple TV), I know there'd be a lot of thankful people! Also, I'd love to contribute to the ongoing dev of f.lux (I don't…

I just want to remind everyone that LED backlights emit blue light that isn't eliminated by f.lux or similar utilities.

So if a new macbook pro has:

"15.4-inch (diagonal) LED-backlit display with IPS technology; 2880-by-1800 native resolution at 220 pixels per inch with support for millions of colours"

What possible laptop alternatives are out there that are better for eyes?

Re: Chemists discover how blue light speeds blindness

#273

Post by foo101 »

What would be the right daytime setting in f.lux to reduce the harmful effects of blue light?

The default daytime setting under recommended colors in f.lux is 6500K. I tend to use a daytime setting of 5500K. Is 5500K good enough to reduce the harmful effects of blue light or do I need to go even lower?

Re: Chemists discover how blue light speeds blindness

#274

Post by asadkn »

ScottBurson wrote: post #271

Really surprised there's no discussion here about the ubiquitousness of black-on-bright-white color schemes in apps (including this text box I'm typing into right now, though for the most part, HN uses a soft beige tint for its background; but it's still dark-on-light). It's really quite unnecessary. For code editing I have a light-on-dark Emacs color scheme, which is much easier on the eyes. Yes, Macs have a setting…

For many of us with astigmatism, the trend to default to dark schemes would be quite troubling. They're painfully uncomfortable irrelevant of contrast. There's fuzzing and "halation".

It took me a long time to figure out the why. I love dark layouts in terms of aesthetics, but I cannot use them.

Without being biased, from what I have read so far, the research seems favorable for dark-on-light as long as proper room lighting is achieved and monitor brightness and contrast is adjusted for it. In poor light conditions, the inverse seems to be true.

While there's a reason for current defaults, everything should be optimized for and have options for both black and dark schemes.

Re: Chemists discover how blue light speeds blindness

#275

Post by chrisper »

sc00ty wrote: post #226
chrisper wrote: post #210

Earlier quoted context omitted.

Any reason why you are not just buying a Philips wake up light? I have one and it's great. Especially during darker months

How long have you been using yours? I have been using one for about 3 years. Initially it worked great, but it seems the light just doesn't do it anymore and the alarm sounds are what eventually wake me up.

About a year. But I am having similar experiences.

Re: Chemists discover how blue light speeds blindness

#276

Post by foo101 »

astrodust wrote: post #189
dqpb wrote: post #141

Earlier quoted context omitted.

On the contrary in fact, I find gazing at the blue sky to be calming and enjoyable, and find it promotes diffuse thinking, which can greatly speed up problem solving.

Some people like the smell of ozone. Ozone doesn't have a smell. What you actually smell is your nose burning. Ozone is a very aggressive oxidizer. Looking directly at the sun is also a super bad idea.

> Ozone doesn't have a smell.

This does not sound right. This is what I see on Wikipedia which is also exactly what I was taught in high school:

> It is a pale blue gas with a distinctively pungent smell.

Source: https://en.wikipedia.org/wiki/Ozone

Re: Chemists discover how blue light speeds blindness

#277

Post by oblib »

I bought a monitor a couple years ago that has a "Low Blue Light" feature you can turn on/off.

At first I didn't like it. It kind of dulls the screen down and makes things look greener. But after using it for a couple months, along with a couple other monitors on my desk, my eyes were getting tired so I turned the feature on and used it for a few days to see if I could get used to it.

When I switched it back off afterwards I was pretty shocked at how much more my eyes were instantly stressed. I turned it back on and have left it on since. I also turned the blue down on my other two monitors. And I can feel the difference when I set them back to their defaults too.

I don't think I'd like it for TV, though I might get used to it as well, but for coding and surfing the web it works for me.

Re: Chemists discover how blue light speeds blindness

#278

Post by wingerlang »

dsr_ wrote: post #177
_nkoa wrote: post #32

Earlier quoted context omitted.

Because of the way your eyes work. If it is bright, your pupil will be shrunk, to not be blinded by the luminosity. When it is dark, your pupil will be opened wide up. It is this principle that camera apertures are based on. Now if you have your pupil wide open in a completely dark environment and put a 100% brightness screen at ~10cm of your eyes, what do you expect will happen ? Our eyes are made for nature, that m…

... but I don't put a 100% brightness screen in front of my eyes at night. Do people really do that? Don't they know how to adjust brightness? Indoors, I use about 30% brightness. As the day gets dimmer, that slides down to about 25%. If I'm reading something in bed, I start at about 10% and as my eyes adapt, go down to 1%. When I'm finding it hard to keep my eyes open, I take that as my signal to go to sleep. Am I r…

Some people do it, yes. My girlfriend used to have her phone at 100%. Personally I use f.lux and the lowest setting.

Re: Chemists discover how blue light speeds blindness

#279

Post by bb88 »

mafuyu wrote: post #249
bb88 wrote: post #238

Earlier quoted context omitted.

So those cyan LED's have a forward voltage drop of 3.2-3.6 volts. So you'd be looking at a 32V-36V 350ma power supply or thereabouts to hook them up in series. If it were me, I'd probably run everything in parallel just to keep the voltages lower, and be able to use readily available power adapters. Aliexpress has a PWM controlled constant current driver that takes 5-35V in and outputs 350ma max [1]. 10 of them are $…

Just tested with my power supply, and the minimum V_on seems to be about 2.7V. So if I want to drive all 10 in series, I'll need 30V+. If I had three banks in a 4,3,3 configuration, I could get away with a 12V power supply as well, which would be nice since I already have a bunch of 12V 5A wall warts. I already got the board you linked, supposedly configured for 700 mA. Haven't tested yet. The datasheet for the part…

So note the I/V curve on the diode [3]. The minimum on at 2.7V is probably going to be the "knee" voltage. Sending 1A through the led will be a higher voltage.

The easiest way to test it is to get a multimeter, and put 1A through the led, then measure the voltage across the diode, and that will be the voltage you're targeting. (or you can just use one of the 700ma current regulators for a good estimate, placing the enable to ground.)

Also keep in mind that those current regulators are buck converters and they're not 100% efficient (no regulator is, really). So you're going to want to add 20-30% more power at a minimum on top of the load you're planning on driving with it.

And if you're going to drive 12V of LED's, expect to need 15-18V to drive the buck converter. That's because of the way buck converters work.

The feedback voltage on that chip is a fixed 1.2V and that's used as an internal voltage reference (I guess because they didn't add one into the chip).

They have a circuit diagram for that part, and it looks like CS and Rcs are the most important things on that sheet. CS is the "Current Sense" that measures the voltage across the current sense resistor (Rcs). They give the formula for Calculating Rcs to get to 1A (ILED = 0.155 / Rcs), and I get .15 ohm for Rcs at 1A.

Then you can either replace it with another sense resistor with something like this [2], or an appropriate length of copper wire [1] to give you the correct resistance.

As far as the PWM/enable inversion goes, just invert it in software. 100% full duty cycle would be off and 0% would be on. If you have a Raspberry PI laying around you can easily set one of the pins to PWM to test out your inverter code [4].

I'm going down a similar path to build a UV light box for exposing PCB's and the like.

Best of luck!

[1] http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/wirega.htm...

[2] https://www.mouser.com/ProductDetail/Bourns/CRM2512-FX-R150E...

[3] https://www.electronics-tutorials.ws/blog/i-v-characteristic...

[4] https://circuitdigest.com/microcontroller-projects/raspberry...

Re: Chemists discover how blue light speeds blindness

#280

Post by ScottBurson »

asadkn wrote: post #274
ScottBurson wrote: post #271

Really surprised there's no discussion here about the ubiquitousness of black-on-bright-white color schemes in apps (including this text box I'm typing into right now, though for the most part, HN uses a soft beige tint for its background; but it's still dark-on-light). It's really quite unnecessary. For code editing I have a light-on-dark Emacs color scheme, which is much easier on the eyes. Yes, Macs have a setting…

For many of us with astigmatism, the trend to default to dark schemes would be quite troubling. They're painfully uncomfortable irrelevant of contrast. There's fuzzing and "halation". It took me a long time to figure out the why. I love dark layouts in terms of aesthetics, but I cannot use them. Without being biased, from what I have read so far, the research seems favorable for dark-on-light as long as proper room l…

Fair enough; I don't mind other people using whatever they prefer, as long as I have an option for light-on-dark.

I wonder, though, what the real problem is that you have with dark themes. It could be related to the combination of wide-gamut monitor blacklights and high-index plastic eyeglass lenses. I wrote something about this here: http://scottlburson2.blogspot.com/2016/01/lcd-backlights-and...

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