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Apple investigating improved LED backlights with more accurate colors

post #1 of 34
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Apple is exploring new ways of arranging light-emitting diode (LED) backlights on LCD displays, in a way that could improve color accuracy and allow wider viewing angles.

A new patent application made public by the U.S. Patent and Trademark Office this week describes potential techniques for arranging LED backlights in new ways, and reducing color shift caused by chromaticity (or color quality) variations with LED lighting. Discovered by AppleInsider, the application first filed in February of 2010 is entitled "Backlight Unit Color Compensation Techniques."

In the application, apple notes that LED lighting has replaced fluorescent lighting (CCFLs) to provide backlights for liquid crystal displays. LED has a number of advantages over CCFLs, including higher light output, improved efficiency, lower power consumption, reduced heat, and longer operational battery life.

But due to the manner in which certain LEDs are fabricated, viewing angles -- particularly with phosphor-coated LEDs -- can be poor. Variations in chromaticity can negatively affect the color uniformity of the display, resulting in an inaccurate picture.

The application explains that though LED light is white, it can have a bluer tint at relatively short distances. As the light travels further from the phosphor layer, it becomes more yellow.



Apple's solution would address the issues associated with edge-lit backlights for LCD displays by utilizing a "light guide" Coupled with a "light-extracting surface area," it could compensate for color shift issues found with current edge-lit displays, like those found in Apple's MacBook Pro notebooks.



A light guide would be "configured to provide for propogation of light received from a light source from a first lateral edge to a second opposite lateral edge. A portion of the received light is allowed to reach the second lateral edge and is retro-propagated back towards the first lateral edge. Multiple light-extracting elements are provided to extract and mix the propagating and retro-propagating light, such that the light emitted from the light guide exhibits improved color uniformity."



The application makes mention of using the backlighting technique in any of Apple's products with LCD displays, including the iPhone, entire line of MacBook notebooks, or the iMac. The proposed invention is credited to Chenhua You of San Jose, Calif., and Shengmin Wang of Hsinchu City, Taiwan.
post #2 of 34
Not going for OLED technology?
post #3 of 34
With current viewing angles almost at 180 degrees, is there any more room to go, really? Maybe the are thinking of transparent displays, like the Tom Cruise movie Minority Report
post #4 of 34
Can someone please link to the patent application. With something this complex I'm sure many readers would be interested in more detail than a one sentence description. I Googled around for a few minutes, though, unsuccessfully. Why would the author omit such a crucial piece of information?

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post #5 of 34
Quote:
Originally Posted by QuadESL63 View Post

Not going for OLED technology?

Given the apparent pricing of the larger displays, it's probably not ready yet. Nothing larger than what you'd find in a phone or camera is remotely affordable.
post #6 of 34
I forget how spoiled we are with Apple’s displays. Not that they have the only nice displays around, but I was just playing with a RIM PlayBook and Galaxy Tab at Best Buy (home of the no-iPads-in-stock) and... wow. For about the same price as an iPad, those 7” screens are absurdly small (yet thick and bulky and non-pocketable); and their poor viewing angle gave them a metallic shimmer straight out of 2009.

Quote:
Originally Posted by QuadESL63 View Post

Not going for OLED technology?

Nothing about this says that Apple isn’t also interested in OLED; but AFAIK, OLED’s problems (like color shift over time and usage in sunlight) have not yet been solved at any size, much less at large sizes. LED backlit enhanced IPS seems to be the best display that’s practical now, and that’s what Apple uses. Maybe this patent could improve on that! But Apple patents their inventions whether they’re going to ship them or not. A patent really tells us little about their plans.
post #7 of 34
Correct me if I'm wrong, but wouldn't RGB LEDs solve this problem? The really nice LED backlit displays don't use phosphor-coated white LEDs (which have a poor color gamut), but RGB LEDs, which pretty well match a good CCFL in color gamut.
post #8 of 34
Quote:
Originally Posted by Thefinaleofseem View Post

Correct me if I'm wrong, but wouldn't RGB LEDs solve this problem? The really nice LED backlit displays don't use phosphor-coated white LEDs (which have a poor color gamut), but RGB LEDs, which pretty well match a good CCFL in color gamut.

Yeah, I just read up on it in Wikipedia. That is the type of display I would like.

http://en.wikipedia.org/wiki/Backlight#LED_backlights

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post #9 of 34
Quote:
Originally Posted by Hal 9000 View Post

With current viewing angles almost at 180 degrees, is there any more room to go, really? Maybe the are thinking of transparent displays, like the Tom Cruise movie Minority Report

They are talking about improving the image quality *within* the viewing angles not necessarily making the viewing angles broader.

Some of us have eyes good enough to see the gradients produced by the current system as well as the shifts in colours when the viewing angles change.
post #10 of 34
Quote:
As the light travels further from the phosphor layer, it becomes more yellow.

Some explanations for this surprising effect?

1. Apple as universal presence? Clearly the flaw in Apple's design is that by building their phosphor layer billions of light years from the viewer, red shift has become a significant problem. Another problem is that they had to build the phosphor layers billions of years ago.

2. If we discount time-travel and/or god-like powers, then more likely the flaw is that by placing their phosphors in orbit, the blue light gets scattered by Earth's atmosphere.

3. Abandon science! The magic elves that make LCD displays work have released their yellow gremlins to torment the blue fairies of LED land.

[before people pounce on me, I do realize that the author just chose unfortunate wording]
post #11 of 34
Quote:
Originally Posted by mstone View Post

Can someone please link to the patent application. With something this complex I'm sure many readers would be interested in more detail than a one sentence description. I Googled around for a few minutes, though, unsuccessfully. Why would the author omit such a crucial piece of information?

Almost all of AppleInsider's patent articles are basically just short re-phrasings of reports from Patently Apple.

I don't see this particular article there at the moment, but if you want detailed coverage of Apple's patent moves it's the best and only site of it's kind.
post #12 of 34
They ought to do something. Their current LED backlit displays have a poor color gamut (~72%?), and poor "color quality" (uneven distribution of color intensity across the spectrum). Even the Cinema Display doesn't do that well in testing, especially compared to CCFL backlit LCDs like the higher end models from Dell (>100% gamut, even color quality).
post #13 of 34
Quote:
Originally Posted by QuadESL63 View Post

Not going for OLED technology?

I don't understand the obsession for OLED.

Currently, its a worse technology (with more potential, but its nowhere near) at a higher price. It does nothing but sound great in a feature list.
post #14 of 34
Quote:
Originally Posted by mstone View Post

Can someone please link to the patent application. With something this complex I'm sure many readers would be interested in more detail than a one sentence description. I Googled around for a few minutes, though, unsuccessfully. Why would the author omit such a crucial piece of information?

Here is the patent --

http://goo.gl/TMYmM

Noted here --

http://goo.gl/aqc73
post #15 of 34
Quote:
Originally Posted by djdj View Post

They ought to do something. Their current LED backlit displays have a poor color gamut (~72%?), and poor "color quality" (uneven distribution of color intensity across the spectrum). Even the Cinema Display doesn't do that well in testing, especially compared to CCFL backlit LCDs like the higher end models from Dell (>100% gamut, even color quality).

Remember the "6 bit is good enough, nobody will notice" from the Apple crowd? Good to see that Apple is trying to improve, rather than listening to those guys.
post #16 of 34
Quote:
Originally Posted by Thefinaleofseem View Post

Correct me if I'm wrong, but wouldn't RGB LEDs solve this problem? The really nice LED backlit displays don't use phosphor-coated white LEDs (which have a poor color gamut), but RGB LEDs, which pretty well match a good CCFL in color gamut.

Some LED backlit screens also support localized dimming to provide greater contrast and truer blacks. They can turn off the LEDs in different parts of the screen. So if you have an image with an area of black, you won't see a faint white cast that is typical of LCD panels.

LED edge-lit displays do not support localized dimming. However, LED edge-lit displays have the advantage of being thinner than LED backlit displays.
post #17 of 34
Quote:
Originally Posted by Prof. Peabody View Post

Almost all of AppleInsider's patent articles are basically just short re-phrasings of reports from Patently Apple.

I don't see this particular article there at the moment, but if you want detailed coverage of Apple's patent moves it's the best and only site of it's kind.

That's an always informative site, but they really need to do something about typographically distinguishing between their own editorial comment and the text of Apple's actual patent filings. As you scan down any particular article you can kind of discern the difference, but they seem to go out of their way to make it hard.
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post #18 of 34
I compared the screen in my Samsung Omnia 7 to my friend's iPhone 4. His screen is definitely higher resolution, but overall I think the image was better on my phone because its OLED screen displays the most incredible black levels and the colours are also much more vibrant.

Something else we noticed was that the black bezel on the front of iPhone 4 is also not actually completely black. The black around my Omnia 7 is much, much deeper black and despite this the screen edges are still virtually unnoticeable when a black image is displayed. Did Apple deliberately not use a true black for the bezel of the phone because it knew the screen wasn't capable of keeping up with it?
post #19 of 34
Quote:
Originally Posted by neiltc13 View Post

I compared the screen in my Samsung Omnia 7 to my friend's iPhone 4. His screen is definitely higher resolution, but overall I think the image was better on my phone because its OLED screen displays the most incredible black levels and the colours are also much more vibrant.

Something else we noticed was that the black bezel on the front of iPhone 4 is also not actually completely black. The black around my Omnia 7 is much, much deeper black and despite this the screen edges are still virtually unnoticeable when a black image is displayed. Did Apple deliberately not use a true black for the bezel of the phone because it knew the screen wasn't capable of keeping up with it?

"More vibrant" might be eye catching, but it isn't necessarily desirable if the colors are being misrepresented. Apple seems to have put more effort into accurate displays over punchy displays.

It's analogous to making audio gear with booming bass and sizzling treble at the expense of a balanced frequency range. Might be "exciting" when listening in store, but ends up being irrupting and fatiguing over the long haul.

You also have to look at the actual dynamic range of the screen-- deeper blacks get you part of the way there, but often come at the expense of being able to accurately depict white levels as they get close to clipping. My impression is the the LCD tech Apple is using actually gives you a better useful range over OLEDs deep blacks but compromised whites.
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post #20 of 34
Quote:
Originally Posted by Haggar View Post

Some LED backlit screens also support localized dimming to provide greater contrast and truer blacks. They can turn off the LEDs in different parts of the screen. So if you have an image with an area of black, you won't see a faint white cast that is typical of LCD panels.

LED edge-lit displays do not support localized dimming. However, LED edge-lit displays have the advantage of being thinner than LED backlit displays.

Thin is very important to Apple!

This patent is a bit silly as it sounds like Apple has patented the mirror. Sometimes I'm not very impressed with Apples patents but I guess they have no choice.
post #21 of 34
Quote:
Originally Posted by neiltc13 View Post

I compared the screen in my Samsung Omnia 7 to my friend's iPhone 4. His screen is definitely higher resolution, but overall I think the image was better on my phone because its OLED screen displays the most incredible black levels and the colours are also much more vibrant.

Something else we noticed was that the black bezel on the front of iPhone 4 is also not actually completely black. The black around my Omnia 7 is much, much deeper black and despite this the screen edges are still virtually unnoticeable when a black image is displayed. Did Apple deliberately not use a true black for the bezel of the phone because it knew the screen wasn't capable of keeping up with it?

Yeah, very much this. I read about that when LED displays first came out and was very much looking forward to it, but it seems to be a feature rare on laptops due to the extra thickness and appears to be largely relegated to high end displays on desktops. Bah. I want a decent LCD without shimmery blacks and I'd like to not sell a kidney to get it.
post #22 of 34
Quote:
Originally Posted by wizard69 View Post

Thin is very important to Apple!

This patent is a bit silly as it sounds like Apple has patented the mirror. Sometimes I'm not very impressed with Apples patents but I guess they have no choice.

It's not describing a mirror. Besides, screen backlights already have a mirror-like foil, which is easily found just by disassembling an LCD panel.
post #23 of 34
Quote:
Originally Posted by Haggar View Post

Remember the "6 bit is good enough, nobody will notice" from the Apple crowd? Good to see that Apple is trying to improve, rather than listening to those guys.

I don't remember thinking 6-bit was OK. Six-bit is cutting corners.

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post #24 of 34
Quote:
Originally Posted by Suddenly Newton View Post

I don't remember thinking 6-bit was OK. Six-bit is cutting corners.

I agree. For a while, it seemed like it had to be that way for portable devices. For example, I hadn't seen a laptop or hand held device with IPS screens before iPad and iPhone 4.
post #25 of 34
Quote:
Originally Posted by Suddenly Newton View Post

I don't remember thinking 6-bit was OK. Six-bit is cutting corners.

Yeah, maybe Haggar could provide a link to some "6 bit is good enough" talk?

We get a lot of this, claiming that "Apple people" are forever insisting that everything is perfect just as it is, that Apple need not change or improve anything ever, but I never see citations of anyone actually saying that. It just seems to be an article of faith with some folks.
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post #26 of 34
Am I the only one that thinks the first patent drawing looks like something from Aperture Labs?
post #27 of 34
Quote:
Originally Posted by Suddenly Newton View Post

I don't remember thinking 6-bit was OK. Six-bit is cutting corners.

Here is where it started:

http://arstechnica.com/apple/news/20...o-displays.ars

Apple's marketing claimed "millions of colors" on 6 bit screens that were physically incapable of producing "millions of colors". As you can see from those comments, Apple defenders dismissed the issue.
post #28 of 34
Quote:
Originally Posted by AppleInsider View Post

But due to the manner in which certain LEDs are fabricated, viewing angles -- particularly with phosphor-coated LEDs -- can be poor. Variations in chromaticity can negatively affect the color uniformity of the display, resulting in an inaccurate picture.

The FTC really ought to look into people calling these phosphor-coated LEDs "LED lights". An LED light should be a combination of red, green, and blue LEDs that add up to (some color temperature of) white.

These phospor-coated things are fluorescent lights excited by a blue LED instead of a mercury-vapor tube, and therefore no more efficient than fluorescent and just as subject to "tired phosphor" longevity issues. False advertising, in my opinion.
post #29 of 34
First they need to fix the backlight bleed issues on the iPad 2. Waiting for the official launch in my country soon so I can RMA my iPad 2. Though I can't imagine living without my iPad 2 for more than 2 days (a bit sad, but, meh whatever).
post #30 of 34
Quote:
Originally Posted by Unicron View Post

Am I the only one that thinks the first patent drawing looks like something from Aperture Labs?

Ha Ha Awesome. Just put a small diagram of a cake somewhere on that and it will be complete.
post #31 of 34
Quote:
Originally Posted by Haggar View Post

Here is where it started:

http://arstechnica.com/apple/news/20...o-displays.ars

Apple's marketing claimed "millions of colors" on 6 bit screens that were physically incapable of producing "millions of colors". As you can see from those comments, Apple defenders dismissed the issue.

Actually, I see one person defending Apple. Everything else ranges from mild disappointed to pissed.

And this was all three years ago, when 6 bit laptop screens were the norm. So it's not so much about claiming that 6 bit is plenty good, just that Apple is providing the best screen available and perhaps overstating its capabilities, which is quite different.

And: really? You're grumpy about a discussion that happened three years ago?
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post #32 of 34
Quote:
Originally Posted by Haggar View Post

Here is where it started:

http://arstechnica.com/apple/news/20...o-displays.ars

Apple's marketing claimed "millions of colors" on 6 bit screens that were physically incapable of producing "millions of colors". As you can see from those comments, Apple defenders dismissed the issue.

FFS. It produced millions of colors through dithering, it still produces 16+ million colors, just not as nice as a true 8 bit display. It's an industry-wide practice that was needed to make the best of a bad situation in laptops. You're singling out Apple when there weren't any other companies selling true 8 bit displays in laptops, except maybe for niche applications.

Quote:
Originally Posted by Mac-sochist View Post

The FTC really ought to look into people calling these phosphor-coated LEDs "LED lights". An LED light should be a combination of red, green, and blue LEDs that add up to (some color temperature of) white.

These phospor-coated things are fluorescent lights excited by a blue LED instead of a mercury-vapor tube, and therefore no more efficient than fluorescent and just as subject to "tired phosphor" longevity issues. False advertising, in my opinion.

To say it's no more efficient just because of the phosphor conversion isn't completely true. You have to account for the inefficiency the CCFL ballast, and the original generation of the blue/UV light isn't the same process, LED for one vs. a vapor arc in the other.
post #33 of 34
Quote:
Originally Posted by QuadESL63 View Post

Not going for OLED technology?

I don't think OLED will ever be practical enough for larger, more permanent displays. Too many compromises with the largest being the shorter life of the blue elements that cause color shifting over time as the blue "wears out" first.

I expect quantum dot LED to take over - not just for displays, but for general lighting.
post #34 of 34
Quote:
Originally Posted by addicted44 View Post

It does nothing but sound great in a feature list.

And that's where the interest in it comes from
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