New LED Backlights For LCD Screens

stuffman64 writes: "LumiLeds has a new LED backlighting technology based on their Luxeon Star LEDs. It is meant to replace the power-hogging CCFL lights currently in use. Benefits include longer battery life for notebooks, less weight, and a larger color gamut (up to 130% of the NTSC standard). The release can be found here." I wish I could hook up one of their evaluation kits to my machine right now;) The same site has quite a lot of LED-related information throughout.

Comments

Hmm....

[sllort]

". The shade of red lipstick you purchased on the Internet and viewed on your LCD monitor will be the exact color red you receive in the mail. "

That's great. Exactly who is this press release for, anyway?

Re:Hmm....

[tim_maroney]

The shade of red lipstick you purchased on the Internet and viewed on your LCD monitor will be the exact color red you receive in the mail.

That would appear to be an actionably false claim. Color calibration can only go so far, especially when dealing with aspects of color that are not captured in current displays such as reflectance, and when mapping between different color gamuts.

Calibration also gives incorrect results when mapping between different kinds of color. Monitor color is additive, while real-world colors are usually subtractive.

Finally, color is heavily affected by ambient light conditions, to which monitors and real-world objects respond differently.

Calibration can reduce differences but it comes nowhere close to removing them.

Tim

Re:Hmm....

[srvivn21]

The shade of red lipstick you...[noticed] on your LCD monitor...

It's okay to love your LCD monitor, just don't looooove your LCD monitor...

Re:Hmm....

[TheTomcat]

The same is supposedly true of lighting conditions when VIEWING the monitor.

The design agency I used to work at spent a small fortune on upgrading their lighting to Pantone approved bulbs and tubes.

mini-version

[Erasei]

I think this would make a very cool addition to a mobile mp3 player. Instead of the little screens they have now, we can get some larger ones with better GUIs, due to much lower power usage.

Re:News?

[baptiste]

Who said /. had to only publish recent news? This is a really cool technology - news for geeks. I doubt many /. readers even knew these existed - so it IS news. That's why I'm an avid /. fan - not that they are one of the first with the 'latest' news (though they often are), but that they publish links to more obscure news/info I might never come upon in my daily net travels.

Argh, my eyes

[Jeffrey Baker]

Their power-saving plan works by alternating the duty cycle of their red, green, and blue LEDs at 1-65Hz. I can feel a headache coming on already.

Re:Argh, my eyes

[BeBoxer]

I think the LED's are inherently more efficent than the fluorescent lamps currently in use. They will certainly be more durable and probably cheaper in quantity too.

I'm not really sure what the color flashing is for. Maybe you could use a monochrome LCD and cycle it while changing the colors to produce a full-color effect? That might be a lot more efficient than the current color-filters which absorb a lot of light I'm sure.

Re:Argh, my eyes

[ErikTheRed]

I think it's to appeal to the people who ring their license plates and undersides of their cars with those annoying neon lights.

Re:Argh, my eyes

[ConceptJunkie]

Blue LED's are now plentiful, if a little costly, and are much brighter than other LED's you might have seen (some approach 10000mcd!). They were first developed in the early 90's by some Japanese guy whose name I am too lazy to look up.

You can buy awesome blue (also white) LED's from Radio Shack for about $3 or $4 a piece, cheaper from electronics sites on-line. Those babies are painfully bright... not your Daddy's LED's. I made a flashlight with a single white LED at the end of a piece of intercom wire with a 9v battery pack. I use it for looking around in computers and other cramped places, reading (much better than those Itty-Bitty Book Lights), and entertaining my kids.

Re:Argh, my eyes

[Salamander]

For those who don't feel like building their own flashlight, check out CMG's Infinity Task Light. The LED lasts forever, and it boasts 40+ hours of continuous use on a single AA battery. I use NiMH batteries, which work even longer. The light is bright and rock-steady. I have a blue-green one that is by far the best camping light I've found - whether for reading in a tent or for late-night walks.

Re:Argh, my eyes

[Pope Slackman]

Maybe you could use a monochrome LCD and cycle it while changing the colors to produce a full-color effect? That might be a lot more efficient than the current color-filters which absorb a lot of light I'm sure.

I was thinking that too. Not only could you get potentially better battery life, but 3x the resolution on current displays, since you don't need 3 subpixels for one color pixel.

C-X C-S

Re:Argh, my eyes

[rneches]

You are right, most people can't see changes that cycle faster than 30 or 40 Hz. However, it is possibible to perceive flicker that is much faster than that. For instance, all CRTs will eventually give me a headache, even if I can't actually see the beam rastering across the screen. At 60 Hz, I can easily see the flickering whenever I blink, move my head, or look at or away from the screen. If you can't see the raster as easily, try waiving your hand in front of the screen. The same effect occurs in films, wich operate at 24 frames a second. 24 FPS is more than good enough for most things, but if you happen to be looking near the edge of the screen when the camera pans, zooms or joggs, you will clearly see the flicker.

I drive my monitor at 85 Hz, and I can look at it for about three hours before it starts to get uncomfortable. I know it isn't because I have a crummy monitor, it's a nice 20" flat surface Trinitron, or because of florecent lights since I use indirect hallogen lighting in my office.

In comparison, I can use my laptop, which has a much smaller LCD screen, for as long as I can pay attention. When I turn down the brightness and use my anti-eyestrain fonts and themes, I can hack for 24 hours at a stretch. The reason is because LCD screens do not flicker - LCD screens do not draw the screen by flashing one pixel at a time. If you or a friend have a laptop, try putting it next to a CRT. Set the CRT to the highest refresh rate it can handle, and set the laptop to the lowest refresh rate it can handle (although, for the laptop, it really doesn't matter, and you may only have one choice anyway). Waive your hand in front of the CRT, and then in front of the LCD. You will notice a rather remarkable difference.

The biggest reason that CRTs bug people is because most places use overhead florecent lighting. In the United States, all florecent lights flicker at 60 Hz, and 50 Hz in Europe and a lot of other countries. Chances are, your CRT and the overhead lights will flicker out of phase with one another, causing a much lower frequency strobing effect. The effect may be very subtle, but it will still drive most people crazy, even if they can't see it directly.

If these new LED backlit LCDs have the same flicker that CRTs do, I'll happily stick to the older technology. For the average person who doesn't need a no-flicker screen for 30 hour hacking sessions, these new screens will be awsome.

Re:Argh, my eyes

[ConceptJunkie]

Thanks to his inventions we may soon kiss incandescent lights goodbye forever. The savings in both energy costs and reduced landfill would be enormous. There are LED replacements for incandescent bulbs now, but their cost is around $200. Some day, when the cost gets more reasonable, I plan on filling my house with them. I hope Dr. Nakamura gets everything he deserves. Hooray for science!

Re:Argh, my eyes

[jovlinger]

great idea; but it fails on the glacially slow refresh times for LCDs. Many people don't realise that when an LCD pixel turns on or off, the molecules in the pixel physically reconfigure themselves. It takes time for them to react to the... erm guessing here ... elecrical field applied to them.

However, TI had a display-on-a-chip (using mirrors mounted on micro-actuators, iirc) that used exactly this color cycling technique. As always, this was discussed on /. a while back.
But search is down, so I can't point you to the discussion. Make do with the original site instead:

http://www.dlp.com/dlp/default.asp

click on the "see how it works" for a flash animation. The "color" tab describes the process. With a physically spinning color disk. How oldskool!

Re:Argh, my eyes

[rneches]

If at 85 hz you still notice flicker, then you have a really hyper nervous system.

Well, I do have a hyper nervous system. ^_^

But as you (and the post I responded to) imply, the chemical reaction in your retina is not fast enough to directly perceive the flicker of a screen running at 80 or 85 Hz. However, you can indirectly perceive the flicker when it interfeares with other things, causing a strobing effect.

Also, the squeel from the flyback transformer buggs the hell out of me. My monitor is pretty decent in that respect - the transformer must somehow be dampened. But I can't stand the sound of televisions - I can hear that obnoxious squeel from across the street sometimes. I like your suggestion about using a TV tuner card - that's what I did in high school, although that was mainly because TV's were against the rules.

Re:Argh, my eyes

[ivan256]

The flourescent backlight of your LCD screen does definatly flicker(More acurately, the backlight flickers). The DC voltage of your laptop battery is put through an inverter to convert it to AC before powering the lamp. It's just so fast you don't notice it. A dell laptop I took apart once had an 80Hz cycle. I'm sure that they very from manufacturer to manufacturer though. I must say though that it is a different kind of flicker that that caused by redraw. It's more like the kind you'll see at a movie.

The LED backlights also have the same kind of flicker as your current LCD backlight. It's not a redraw kind of flicker, but an all-at-once kind of thing.

X-Mas Tree Lights

[Anonymous Coward]

Wish one of these companies would get a clue and do Christmas tree lights. Extreme low power, long life compared to current plugins (skip the plug-in and go with a straight built) and possibly programmable. Yeah a string might cost $30 but would be paid for in 1-2 seasons . Any of you looking at your Electrical cost?

Whoopee...

[Apotsy]

Maybe now LCDs can get their delta-E values for color accuracy under 6!

Then again, maybe not.

Automotive LEDs

[BigBlockMopar]

According to HP's Agilent optoelectronics spinoff, in the time it takes for the tungsten filaments in your car's brake lights to become red hot, at 75 MPH, your car would have travelled 25 feet.

I've already got some on my 1976 Dodge Ram. When the brake or turn signals go on, it looks like one of those new Cadillac Eldorados. :) Any news of newer and brighter LEDs is always welcomed. They affect our lives in myriad ways.

Re:Automotive LEDs

[GoRK]

Yes, please tell us more about how you did your lamp conversion. I'd be very interested in upgrading my tail lamps and other markers with LED's.

~GoRK

Re:Automotive LEDs

[BigBlockMopar]

I've been thinking about doing this to my Ranger - where did you pick up the LEDs, and are you using integrated 12V ones, or do you have a seperate regulator for them?
Yes, please tell us more about how you did your lamp conversion. I'd be very interested in upgrading my tail lamps and other markers with LED's.

The LEDs are 3,500MCD each, from Mode Electronics. I run a dozen of them.

Under the dashboard and connected to the brake pedal, I used a 7805 regulator to cut the voltage down to something predictable. The regulator also provides overload protection; that is, if the rest of the controller fails catastrophically, the main brake lights will still work.

In the truck's back end, there's a 555 timer IC with industrial temperature range capacitors and resistors doing the timing. The 555 sets about a 15% duty cycle, dumping 5V directly across each LED. The current through each diode is about 200mA. This is the limit of what they're designed to handle, and they get warm. :) A fairly large electrolytic capacitor takes up the slack in what the regulator can handle.

From the back end, the LEDs are every bit as bright as the main tail lights. And because of how I mounted them, they're essentially invisible until I touch the brake pedal.

It's really a slick setup.

Re:News?

[A Commentor]

But if it was really that big of a 'break-through' why haven't we seen laptops announced with it yet?

They claim:

LumiLeds is already working with LCD panel manufacturers for mass adoption and has targeted having LuxeonTM powered backlights on the market by the end of this year.

This doesn't really say much... Placement of the 'and' makes this sentence vague... is it 'LumiLeds and the LCD panel manufacturers target the end of the year' or 'LumiLeds target the end of the year... hum...

Seems like LumiLed's would have announce a partnership or firm agreement with a manufacturer by now if it was on target.

130% NTSC?

[jandrese]

Isn't that kind of like saying your new car has better acceleration than a diesal Rabbit? NTSC doesn't have particularly good color fidelity last time I checked. Besides, I'd try to avoid associating color performance with NTSC[1] as much as possible from a pure stigma point of view.

[1] Never The Same Color

Bright Blue LEDs

[ayden]

I have one of those blue LED key chainlights you can get at ThinkGeek.com. My friends and I have a new favorite saying:

DO NOT STARE INTO LASER WITH REMAINING EYE!

Re:LED backlighting a LCD

[Jeffrey Baker]

The 65Hz figure is from their datasheet.

Re:Automotive LEDs (OT)

[cr0sh]

I've been thinking about doing this to my Ranger - where did you pick up the LEDs, and are you using integrated 12V ones, or do you have a seperate regulator for them?

Some Canon digicams already use LED backlights

[phr1]

The S100/S110 and S300 Digital Elph digicams use white LED backlights. I'm not sure about the bigger models (G1, G2, Pro90IS). I have an S100 and the backlight is great. Good color, and none of the turn-on delay or flickering of fluorescent backlights. The LED's are at the edge of the screen, but the lighting is still pretty even. That may be because it's just a 2" digicam screen. I've been wondering for a while whether it would be a problem for bigger (laptop sized) screens.

Er, um, ok. well, sure.

[alhaz]

Most LCD monitors are probably far beyond 130% better than NTSC. No big deal. They don't call it "Never The Same Color" for nothing.

Being lower power than CCFL isn't impressive. I also would not want to buy a laptop that used a side-lighting system of any kind, be it fancy-dandy LED or CCFL, because side lighting systems simply can't illuminate the whole screen.

LED side-lights have been around a long, long, long, long, long time. They are lower voltage than ccfl or EL, but both ccfl and led draw more amps than electro-luminescent backlighting.

That being said, the reason not everything uses EL is because EL is *expensive. And sometimes it's not bright enough for the task. iPaqs appear to be CCFL side-lit, for instance, and are freakin bright. side-lighting works well on a pocket computer becaise the screen is small enough that it can be uniformly lit from the side.

LCD technology has been improving every day, getting brighter and lower power. Maybe they've figured out a way to run a lot of white LEDs on only a little power, and this may presumably save you the cost and space of implementing an inverter to drive an EL or CCFL.

But it sounds to me like the the major thing they're shooting for is cost savings. if you wanted bright on a real small screen you'd go CCFL, and if you wanted low power you'd go EL. this sounds like they've made LED side-lights better than they used to be, but I doubt they're as good as other technologies.

I'd have to see a CCFL side-lit device right next to one that's been retrofitted with one of these fancy new LED side-lights before I'd advocate it from a quality-of-experience perspective.

argh

[jbridge21]

All of these parameters that can be adjusted about the backlight... white point, brightness, color-cycling (ugh)....

I'd only be happy with one of these if all three of those were user-adjustable (and that includes turning off the last one).