An Apple patent application published on Thursday reveals the company is actively researching advanced quantum dot-enhanced displays, a next-generation technology that has the potential to reproduce highly accurate and vivid colors.

Source: USPTO

Apple's patent for a "Quantum dot-enhanced display having dichroic filter," published by the U.S. Patent and Trademark Office, offers a highly detailed look at both quantum dot tech and how it can be applied to portable devices like the iPhone.

Quantum dots (QDs) are technically nanocrystals - in some cases smaller than a virus - made from various semiconductor materials that exhibit special quantum mechanical characteristics. Of interest to display makers, as well as other industries in the optics field, are QDs' light-emitting properties. Specifically, the material can be "tuned," or manufactured, to emit very narrow spectrums of light.

According to the filing, the electronic properties of QDs are defined by their size and shape, meaning the colors emitted during excitation can be controlled through fabrication. Nanocrystal size and wavelength emission (more accurately bandgap energy) are inversely related, so the larger the QD, the smaller the emission frequency.

Applied to color, bigger dots will skew toward longer wavelengths like red, while smaller dots emit shorter, higher frequency wavelengths like violet. For example, a cadmium selenide quantum dot may be tuned to gradually reproducing the entire visible spectrum, ranging from approximately 460nm (blue) to 650nm (red). This ability to change color by varying nanocrystal size is unlike current phosphor- or organic-based LEDs, which emit light in a fixed spectrum.

In Apple's invention, as with other proposed implementations, a dichroic filter is disposed on a quantum dot-enhanced film (QDEF) in an red/blue/green (RGB) LCD display.

One embodiment calls for a non-QD light source that emits a blue light be combined with a light emitting layer of two QD groups, one red and one green. The layer, possibly a nano-film, is positioned above the first illumination source, thereby absorbing a portion of its blue light to emit red and green light. A second portion of the blue light is allowed to transmit through the QDEF.

The dichroic filter above the QDEF then reflects some of the transmitted blue light back down to be recycled, while allowing an even smaller portion through as white light.

In the embodiment discussed at length in patent application's body, the display also implements an LCD that controls passage of the aforementioned white light through color filters arranged in subpixels. This would provide extremely accurate color reproduction.

A less confusing way to imagine Apple's invention would be to follow light emitted by the LED backlight unit. First, a normal blue LED emits light that is sent to a light guide panel. The LGP evenly distributes the light to the back of an LCD panel with color filters arranged in subpixels.

At this point, instead of using phosphors to produce red and green light, the QDEF's quantum dots are brought to photoluminescence by the blue light, which consequently produces red and green light. The dichroic filter then reflects some of the blue light transmitted through the QDEF back to the QDEF, thereby increasing excitation and red/green output.

Color gamuts of QDEF displays compared to sRGB and Adobe RGB.

The filing goes on to explain how brightness can be boosted using prisms and other light forming techniques. Also noted in detail are candidate semiconductor materials from which QDs and QDEFs can be fabricated in a non-toxic manner.

It is unclear if or when Apple will use quantum dot technology in its devices, though the company has a history of delivering some of the best displays in the industry. Recently, however, the colors reproduced by the iPad mini with Retina display were found by one study to be less accurate than competing tablets, possibly leaving some room for improvement.

Apple's quantum dot-enhanced display patent application was first filed for in 2012 and credits Chenhua You as its inventor.

Sony is already using quantum dots in its high-end Full HD and 4K TVs to expand the color gamut from sRGB to x.v.color. But it only makes sense if the content is also encoded in a larger color gamut (nor movies, games or TV content is atm.), otherwise the sRGB colors will be "stretched" and become inaccurate.

Yes, john is right. We already seen this technology before and thank god, I have my Sony Bravia 4K ready television. There are rumors about iPhone 6 screen that it will come with a curved shaped screen

Sony is already using quantum dots in its high-end Full HD and 4K TVs to expand the color gamut from sRGB to x.v.color. But it only makes sense if the content is also encoded in a larger color gamut (nor movies, games or TV content is atm.), otherwise the sRGB colors will be "stretched" and become inaccurate.

It could make sense for Apple to use it in for example a 4K display for the Mac Pro or an iPad Pro. Wider color gamuts is mostly for professional use right now.

What do you mean by encoding? If Apple adds this display to their products as well as camera apps that can encode for this as well as starts encoding all their iTunes content for QD doesn't that give him a lead?

What do you mean by encoding? If Apple adds this display to their products as well as camera apps that can encode for this as well as starts encoding all their iTunes content for QD doesn't that give him a lead?

If you look at Apple history and they have a pretty good track record of betting on the right tech horse to move them forward. If there past correct decisions is any indication of why they are or are not using a particular technology in spite of all the so call experts who think this or that is better. You have to ask yourself, why Apple is not currently using all these various so call better display technologies if they are suppose to be the leader. Well maybe it is as simple as they may not work well, their reliability is still questionable. Apple already has had quality issues with proven technologies why would the risk putting million of a product into customer hands when they know it may not be ready.

Just because Samsung, Amazon or Google choose these new technologies does not mean they know something apple does not no or apple is falling behind. Those companies I would not characterize as bell weather companies when it come to quality and performance. All three of those do not care if they product do not work in a year, they actually preferred they not work since you will have to buy again which helps their next year profits.

At this point I am think there is something which is not quite right with these technologies which Apple is waiting to see how they improve with time. In the mean time they are shipping the best known product which will meet customer expectations.

Also keep in mind these company still are competing on specmanship, they trying to win over customer simply because they have a product with better spec, not that it brings any value to how you use the product, but they can see that have better specs or a longer list of features which no one uses but their list is longer.