Apple investigating improved LED backlights with more accurate colors
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.
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.
Comments
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.
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.
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
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.
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]
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.
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.
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
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.
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.
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.
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?
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.
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.
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.