You must log in or register to comment.

undefined7196 t1_j7lndaj wrote

The creators of the bright blue led won the Nobel prize in physics for it as it allowed us to create white light LEDs that are now the most energy efficient form of illumination for homes and saves countless billions of dollars in energy costs.


4Blu t1_j7m197x wrote

I was at UCSB when Nakamura won. He was apparently pretty stoked he didn’t have to teach anymore.


Regan-Spor t1_j7nrcp9 wrote

Now I have someone to blame for the white light headlights I see on cars.


Salami-Vice t1_j7o0pto wrote

Also allowed for the phosphorus converted amber (PC Amber). A bit lighter in tone than a regular amber which is very orangy. Thermally stable like a white, losing only 10-15% of its lumen output at operating temps vs the regular amber which would see 50% loss. Game changer for emergency lighting.


positivecynik t1_j7ln9pe wrote

This is really specifically wild for me to stumble onto here. Let me explain. In the early 90s, a few of us in the clubs were into the whole "cyberpunk" movement that was pretty new back then.

Some club denizens went as far as to create electronic apparel, with an LED or two, and one guy even made a skin temp sensor and connected it to an LED bar graph, so the more he exerted himself the higher his temp would show on his arm.

Anyway.... everyone has either red or green or yellow. I wanted a blue. Couldn't find one.

Internet was pretty limited back then, so a lot of shopping in parts stores, catalogs. Etc....

We finally found a supplier in China that manufactured blue LEDs, but we'd have to buy like 250,000. Somehow this dude gets a hold of exactly 5 of them. He worked a deal with a store who ordered the he quantity and let him buy 5.

Craziest thing, the turn on voltage for the ones We used was 6V. So, strapping 4 AAA batteries somewhere on you would give you 6V.

These blue LEDs from China needed 5V.

Took a while, but we figured out that rechargeable batteries output 1.25V, so we used 4 of those to achieve the 5V turn on voltage. The whole thing took about a year while we figured it out.

Haven't thought about it in 30 years. Then I run across this random article telling me exactly why what I tried to do 30 years ago was so difficult.



Thelgow t1_j7luawl wrote

Funny you should mention rechargeable batteries. A while back, 14 years or so ago, I was dabbling with electronics and wanted to swap my xbox360 controller and front panel led's from Green to something else, like purple. I ordered a bunch of purples, blues, reds, etc. I wire up the purples to the controller. Nothing. And these were so small, if the soldering iron stayed on it for more than 2 seconds it literally would disappear in a puff of smoke.

Apparently I'm telling this out of order but it helps. I did the red ring on the 360 front panel with the purples fine, so I know theyre good. I replace the purples with blues and it lights right up. I put purple back, no dice. I'm fiddling around and I forget how but I plug the charging wire into the controller direct and I get flashbanged by purple lights. Similar to your story I found out the rechargables had less voltage. So the red ring front panel is hardwired and getting full juice, but wireless, no dice. Pop in the usb charger and yeah it would light up. Also confirmed regular AA's would work, but I already had all these battery packs so I wanted to stay with the lower voltage.

So I opted for a blue/red/blue/red X pattern and left the purples for the front panel. Cool side effect was that as the batteries died the blue led's would get dimmer and dimmer until you just had 2 bright red led's and then the controller would just die. I think this may be a reason they favor red for emergency systems as it seems to require less power.


strangr_legnd_martyr t1_j7lzy1d wrote

Red LEDs do require less power. The forward voltage on a red LED is about 1.8V at 20mA. The forward voltage on a blue LED is about 3.6V. That's 36mW of power for red vs 72mW of power for blue.

Blue light has more energy than red light (higher frequency/shorter wavelength).

I think they generally favor red over blue for emergency systems, though, because red light has less effect on low-light vision. So if the power goes out, your red-lit emergency signs don't blind you in the dark.


Thelgow t1_j7m0bd7 wrote

That too because lord knows what happens when the tape falls off my optical to rca adapter. Why this thing has a Batman spotlight built into it, I'll never know.


Ok-disaster2022 t1_j7mdka0 wrote

However there's an issue with emergency signage. Red is the color of danger, stop, while green is safe, go. Exit signs in areas of low literacy are green and green are becoming more common in the US to be more inclusive of people who can't read.


Marzgog t1_j7qj8dt wrote

My country has among the highest rates of literacy in the world and our exit signs are green. I don’t think inclusivity has anything to do with exit signs going green, it’s just one of those universal standards in the making.


KentDarkmere t1_j7lqpf5 wrote

I think I would of just used a resistor in parallel with the led


nocrashing t1_j7lxfkk wrote

Series but yeah


Admetus t1_j7opryj wrote

Also wouldn't the internal resistance of the batteries mean those blue LEDs were drawing less than 5V? 🤔


ItDoesntMatter59 t1_j7mws9q wrote

You are supposed to use a current limiting resistor. LEDS dont last long with excess current which you will get without one


shalafi71 t1_j7ntsek wrote

I was arguing with a (much smarter) friend about resistors one day. He insisted that if you got the voltage right, you didn't need one. "Dude, LEDs pull amps until they burn, sometimes instantly. You have to either get stupid lucky with current and voltage or you have to use a resistor."

To this day he doesn't believe me. "Dude, take a $1 store light apart, there's a resistor soldered onto the hot lead. Every. Time. Why would China put unneeded parts in there?!"


TrumpterOFyvie t1_j7lomvz wrote

I hate blue LED's. My eyes can't focus on them properly. If you show me a red LED ticker alongside a blue one, the red letters are pin sharp to me and the blue letters are blurred as if I'm not wearing glasses.


Splice1138 t1_j7m56uj wrote

You might be a more extreme case, but human eyes can't focus on blue light as well, period. I know this first hand (and second, and third) from calibrating three tube RGB projectors back before LCD/DLP.

I also read about it being used in image compression. If you split an image into R, G, and B channels, you can save the B at half resolution and the difference is nearly imperceptible to human eyes, whereas it is easily seen if you do that with R or G.


Ok-disaster2022 t1_j7mdrk1 wrote

It's frustrating that the headlights from heall are more blue tinted, so no only ate they brighter, but the person using them can't see as well, so they make them even brighter.


Couldbehuman t1_j7mv5wo wrote

>I also read about it being used in image compression. If you split an image into R, G, and B channels, you can save the B at half resolution and the difference is nearly imperceptible to human eyes, whereas it is easily seen if you do that with R or G.

Never heard of chroma subsampling happening in RGB, generally that's converted to something like YUV which is a Y channel of luminance (about 58% derived from the green channel) and two UV chrominance channels. Both channels of chrominance are then subsampled horizontally by 50%, reducing 1/3 of your original data without even getting to the compression stage. Pretty much all compressed video you ever watch has the chrominance subsampled 50% vertically as well, meaning you've cut the original data size in half.

Point is, not just blue getting subsampled, and since that's what everyone is constantly watching it's pretty safe to say it turned out alright.


Splice1138 t1_j7n8hfi wrote

The page I read it on might have been simplifying things, not saying that's exactly how it's implemented. I do know if you play around with subsampling RGB chanels via Photoshop, for example, blue is the least noticeable, red somewhat, green very noticeable.


gk99 t1_j7n356x wrote

There's a movie theater where I live that chose to make its menu all bright blue LEDs and it's almost literally impossible to read.


WillTFB t1_j7m36pp wrote

Wonder what the science behind this is


planoavid t1_j7m6nu8 wrote

The lens and cornea of the human eye absorbs shorter wavelengths (blue) better than longer wavelengths (red) so less blue lights reach the retina.

The cones the retina uses to see longer wavelengths are active over a wider array of wavelengths vs the blue cone.

So it is easier for your eye to sense longer wavelengths of light than the blue light.


ozyx7 t1_j7oeneq wrote

Eyes evolved to be most receptive to things of interest.

Things in nature that are green are very interesting. For example, plants. It's probably important to be able to focus on those, especially if you're arboreal.

Things in nature that are yellow or red are also interesting. For example, fruits, blood, and poisonous things.

Things in nature that are blue are much less common. By far, the most prevalent blue thing we encounter is the sky, and that isn't something that we need to focus on.


AtraposJM t1_j7xrlta wrote

Not sure this is true but I have a degree in graphic design and I had a teacher tell me that men see yellows and greens a little bit better than women do because when hunting they'd have to see movement in grass etc. Was told to be aware of over correcting for yellows and greens when colour correcting photos and things.


pebbleinflation t1_j7lsoj0 wrote

I remember the late 90s, when electronics started being plastered in blue LEDs, for a "futuristic" look. Usually combined with silver coloured plastic.


nolo_me t1_j7mp2hy wrote

My idea of classy is still stuck on brushed alu and blue LEDs.


rockmsedrik t1_j7lnoor wrote

Blue LEDs have replaced amber tone activity lights in most electronics, and the disturbance to sleep patterns is evident in everyone’s behaviors globally. I have to tape over nearly every LED on every piece of electronics to tone it down enough. Otherwise it illuminates an entire area if the lights are turned off.

Blue LEDs are the scourge to sleep.


TrumpterOFyvie t1_j7loq1p wrote

Just get a nice pillowy sleep mask. Absolute pitch black heaven.


rockmsedrik t1_j7lp6ee wrote

If you wake up to go to the bathroom, sleep disturbed. Gotta turn off and black out those blue lights. Sleep masks are nice, but only helps while you have it on.


leoleosuper t1_j7niqac wrote

Learn how to go to the bathroom without sight. Helps a lot.


rockmsedrik t1_j7njjtm wrote

Ah yes, the touch-n-feel method, I too have stubbed my toe a few too many times!


RockItGuyDC t1_j7mnjkg wrote

I understand that it's not always possible for everyone, but this is exactly why I have zero electronics in my bedroom (aside from my phone charging on my bedside table, but that doesn't have an always on LED).

That plus blackout curtains have really improved my sleep!


rockmsedrik t1_j7n1326 wrote

Agreed, best to have forms of RF away from sleep spaces, current situation has a single room for both work and sleep, so black out curtness, sound absorbing wall blankets, and blacking out all BLUE LED's on things. Even the RED LEDs on power strips are too bright now. Have to tape over them as well.

Thankful to Lévoit Air purifiers for having the option to TURN OFF the LED panel. Also thankful to Govee humidifier for having a "LED panel brightness, and schedule on and off" settings.

More electronics need to think about the brightness in dark rooms. Light pollution is a ongoing battle.


zed857 t1_j7m37rh wrote

Connect that stuff to a power strip with an on/off switch and turn the whole lot off when you go to bed. Apart from your phone charger it's not like you'll be using those other electronics when you're sleeping.


rockmsedrik t1_j7mhh8p wrote

For the few of us that lack a separate office for our equipment, some of us need to live in one room, I use my computers to render video, and to render 3-D projects while I sleep, it’s crazy that I have to black out all the LEDs just to keep them quiet.


wufnu t1_j7m5dw1 wrote

First bright blue LED I ever saw was on the PS2. I got a week to play with it pre-release due to work. Before and after gaming sessions at night, that piercing blue light felt like the goddamned future.


nomoregroundhogs t1_j7mt05z wrote

Same. Among certain specific geek circles it was a huge deal at the time that the PS2 had a blue LED.


nVr78 t1_j7lsgyr wrote

Interesting.. so what you’re saying is that people back then could fall asleep immediately, even right after using their iPhones?


shodan13 t1_j7myr8f wrote

Fucking quantum physics man.


Jaksmack t1_j7m0gsb wrote

In 98 or 99, blue LED's we're still so expensive that I bought 1 to replace the green LED on my PC's power light. I was going to put them all over the PC case, but instead went with some cold cathode tubes.. the tubes and power supply was still cheaper than buying 1 LED. If I remember right, the LED's were like 25$ each..


Morall_tach t1_j7lsoj4 wrote

I remember when red LEDs first became affordable and widespread, we used them on our boat to read charts in the dark without ruining night vision. But the gap between those first cheap red ones and LED screens or bright white ones for headlamps and flashlights seemed like it took forever.


the_hell_you_say t1_j7o1cy1 wrote

I was working the night shift in an electronics lab around the time when blue LEDs became cheap. I took apart my desk phone and replaced the red "you have voicemail" LED with a blue one. I always left voicemail in my inbox after that.


Vanish_7 t1_j7o8kf1 wrote

(*looks around at BattleStation, currently 100% enveloped by blue LED light*)

Hmm. Glad that shit got worked out.


rainwulf t1_j7tf6a9 wrote

I remember during a school trip to the science museum (i am 45 now) they had LEDs of all the colours at the time, and the blue one was like "woa"


sysable t1_j7lu94h wrote

They were extremely expensive when they first became available. The blue LED power indicator in a preamp added $200.00 to the cost (including markup) according to the design engineer.


____Theo____ t1_j7nd2j0 wrote

Always wondered why my 1983 VW van’s instrument cluster has different colored LEDs for various indicators, but a white lightbulb with a blue cap for the high beam indicator.


AKADriver t1_j7nord6 wrote

I'm surprised it has LEDs. The indicators that look like red LEDs in my '93 Nissan are all tiny bulbs, even though red LEDs had existed for a while.


OccamsMallet t1_j7oanvo wrote

I remember buying blue LED Christmas lights back in the day ... they were so expensive but looked so cool. Now they are stuck in throw-away plastic signs.


SeraxOfTolos t1_j7lmiix wrote

Blue light was so rare, we didn't have glasses