Color IQ

As I mentioned earlier, the technology at the heart of the Philips 276E6 monitor is QD Vision's Color IQ quantum dot technology. To gain a better understanding of how this differs from other quantum dot implementations currently used in the market, I spoke with QD Vision's Chief Marketing Officer John Volkmann.

Quantum dots are a type of semiconducting nanocrystal. They're typically made of cadmium selenide or indium phosphide, and when used in displays they have a diameter less than ten nanometers. What makes them interesting is that they exhibit a property known as photoluminescence, which means that they emit light after absorbing photons.

In LCD displays this property is highly desirable, as it means that you're able to place an array of quantum dots between the backlight and the color filters to reduce the frequency of the light emitted by the blue backlighting. By altering the diameter of the quantum dots you can control the frequency and wavelength of the light that is emitted, which allows for the emission of specific red, blue, and green wavelengths at the required intensity to cover your target color gamut. Smaller quantum dots on the scale of one or two nanometers emit wavelengths of light in the blue part of the visible spectrum, while larger quantum dots with a diameter of six or seven nanometers emit red light.

A question you may have is why this is actually necessary. I mentioned above that quantum dots are typically used to convert blue light into red and green light, and the use of blue LEDs for backlighting is not unique to quantum dot displays. Almost all modern LCD displays use LED backlighting, and the majority of them use what is commonly referred to as WLED backlighting. In truth, these "white" LEDs are really blue LEDs paired with a yellow phosphor, and through this process wavelengths of blue, green, and red light are produced. Unfortunately, there is still a very significant blue bias in the final output, and the intensity of the desired red and green wavelengths is relatively low. Because of this, these displays are limited in the range of green and red colors they can reproduce, and to date most monitors of this type have been limited to roughly 99% of the sRGB color gamut.

To produce a wider color gamut with LED backlights alone, vendors have employed the use of different technologies. The most prominent is GB-r backlighting, which pairs green and blue LEDs with a red phosphor to allow for green and red light of a greater intensity. Unfortunately, such designs have shown to be quite expensive, and this has kept wide gamut displays priced well outside what is affordable for the average consumer. An even smaller group of displays has employed full RGB backlighting, but due to cost this did not see much adoption by any display vendor.

The cost-related issues of RGB and GB-r backlighting is the problem that QD Vision hopes to solve with their Color IQ technology. Color IQ's appeal is that it works with standard edge-lit displays, and it takes advantage of the blue LED backlighting that those displays employ. Most quantum dot technologies require the use of expensive full-array backlighting because they use a thin film layer with quantum dots embedded throughout it which sits between the backlighting array and the color filter layer. In contrast, Color IQ uses small glass cylinders that sit in front of the blue LEDs at the edge of the display. According to QD Vision, the cost of a film-based solution for a display around the size of a 50" television can cost around $100, while their quantum dot solution for edge-lit displays will only cost around $20.

With QD Vision's current technology the cylinders with quantum dots sit between the blue LEDs and the light guide plate that distributes the light across the panel. With such an implementation one can expect displays that closely cover the Adobe RGB and DCI-P3 color gamuts depending on exactly how the quantum dots are tuned. According to QD Vision, quantum dot technologies perform best when the quantum dot array is as close to the backlight as possible. Within the next few years they hope to be able to deliver a "chiplet" solution, which consists of a quantum dot matrix mounted in a bead of glass right atop the LEDs. Moving beyond that will be integrating the quantum dot matrix right into the LEDs themselves. Right now such solutions are infeasible due to heat degradation, but they will be necessary as we move toward full coverage of the Rec. 2020 color gamut.

Philips 276E6: The First Color IQ Desktop Monitor Contrast, Brightness, and Gamut
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  • ImSpartacus - Thursday, April 28, 2016 - link

    Fascinating read. Intuitively, I didn't anticipate a downside to a wide gamut monitor, so that's interesting to learn about.

    Though, honestly, as a layman, I have little use for something with that much potential. Cheap Korean panels, hooooooooo!
    Reply
  • nathanddrews - Thursday, April 28, 2016 - link

    This is only the beginning. With the advent of Rec. 2020 HDR monitors, we are looking at an even more complex calibration system. Even now, HDR televisions effectively have no way to calibrate to a standard. Supposedly Microsoft is working on a W10 update to improve color support for 10-bit and HDR... but without a sincere, ground-up overhaul of color handling, I don't think it will amount to much.

    Gotta keep the hope, though. I really want to play some HDR games on OLED.
    Reply
  • Michael Bay - Thursday, April 28, 2016 - link

    I dread the day my insider preview build will mention color profiling. Bugs will be atrocious! Reply
  • crimsonson - Thursday, April 28, 2016 - link

    Dolby and SMPTE have offered each a standard for HDR. Reply
  • nathanddrews - Friday, April 29, 2016 - link

    Both of which have no good calibration method yet. Ideally, the unit would come pre-calibrated for both dark and bright environments, HDR10 and DV. Of course, if the player and TV could talk to each other to constrain the nit levels to the calibrated display output... I would be in heaven. Reply
  • BrokenCrayons - Thursday, April 28, 2016 - link

    Yup, monitors that attempt to display colors accurately or at higher resolutions seem like sort of a pain in the backside to deal with. Certainly, there's good reasons for them, but I'm perfectly happy using bottom-feeder 1366x768 screens for the moment. Higher resolutions aren't important and neither is color accuracy. It's great to see the technology maturing, but you could stick me with a smeary old passive matrix LCD panel from a mid-90s era laptop and it'd be fine. Reply
  • Solandri - Monday, May 02, 2016 - link

    As someone old enough to remember the loss of color gamut moving from CRTs to LCDs, I can't wait for sRGB to die so we can move to a more realistic color gamut like Adobe RGB (which is fairly close to the NTSC standard used for CRTs).

    The color profile problem is only a problem when displaying pictures with a certain color profile on a screen with a different color profile. The problem goes away if everyone uses the same default color profile.

    Unfortunately for 20 years now, the default has been the atrocious sRGB. Decades from now, photos and movies shot in this era will be notable for their lack of color saturation, because they were made for the sRGB color space. I quit shooting JPEGs with my DSLR precisely for this reason - my camera's RAW photos cover Adobe RGB space, so by shooting as JPEG I was throwing away a lot of color information.
    Reply
  • willis936 - Thursday, April 28, 2016 - link

    Excellent write up. Lots of info for getting people up to speed on color management. Reply
  • Michael Bay - Thursday, April 28, 2016 - link

    First in was Mami, and now R;N. Animoo certainly conquered AT in these couple of years. Reply
  • Jacerie - Thursday, April 28, 2016 - link

    There's a typo in the title. Quantum is spelled with a U not an O. Reply

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