A new LCD backlighting technology from material science company, Nanosys Inc, delivers the promises of OLED displays at LCD prices.

QDEF - A Stepping Stone or Alternative to OLED?

Jeff Yurek - Nanosys Inc

Filed Under - Video Systems - Flat Panel LCD and Plasma Screens

Who are Nanosys?

Nanosys is an advanced materials architect. We design and build new materials at the molecular level to improve products like tablets, TVs and even electric vehicles. Our products enable stand-out electronics using known, viable manufacturing processes. Our ability to engineer new materials allows us to create products with performance capabilities far surpassing today’s standards like TVs with lifelike color and batteries that last all day.

What is QDEF?

QDEF is a new kind of backlight technology that’s going to enable a new generation of LED backlit TVs that have OLED-like performance at only a fraction of the cost.

Display performance is all about light- how much can I generate, how efficiently, how wide a range of colors, and how much resolution can I pack in? QDEF gives LCD makers a way to tune the spectrum of light in the backlight and dramatically improve picture quality. It does this with millions of tiny nanoscrystal phosphors, called “quantum dots.” These “dots” emit light at a very precise wavelength and can be controlled by their size. We use a mix of different color emitting dots to create the perfect backlight for your LCD. The result is richer, more saturated color that’s more true to life.

Jeff Yurek from Nanosys describes QDEF in detail in this article.

[Ed] For more detail on LCD display anatomy, see Bill Hammack’s excellent video.

What are the advantages of QDEF over today’s backlit LED displays?

QDEF is also an LED-based LCD technology but there are some key differences and advantages compared to today’s LED TV’s.

A standard LCD backlight creates white light using a technology called YAG (yttrium aluminum garnet) phosphor. YAG produces a two-color spectrum, dominated by blue and accompanied by a broad, yellow component. It lacks a strong red and green element and this results in poor color performance.

QDEF creates a pure white backlight that is designed specifically for LCD displays. This light, made up only of narrow spectral peaks in red, blue and green wavelengths, allows for wide color gamut performance when mixing these primary colors at the pixel level. It does this with great efficiency, so it doesn’t sacrifice the brightness of the display.

As you can see in the comparison below, the 47 inch HDTV on the left has been modified with Nanosys’ QDEF technology. It shows a much wider range of colors, note the difference in the greens here.

 

QDEF seems to be a viable alternative to OLED. What technical advantages and disadvantages does QDEF have over OLED?

QDEF offers the same high color gamut performance as OLED, while also offering a brighter, more energy efficient display. Unlike OLED, QDEF displays can be made for very large sizes.

Color Purity

Both OLED and QDEF are able to reproduce greater than 100 percent of the NTSC color gamut. In our experience, (see measurements below) QDEF can deliver more, especially in terms of red. This means that QDEF can offer more coverage, not just area, of more of the industry standard high gamut formats like Adobe RGB, DCI-P3 and NTSC.

[Ed] For more detail on color gamut, see our previous article

Efficiency

This is a difficult comparison to make since LCD and OLED are such different technologies. OLED is emissive, meaning each pixel is also a light source, and so the amount of power it consumes is dependent on content. For example, if a pixel is black, it is consuming no power while a white pixel can consume a significant amount of power due to the inefficiencies in the underlying material system, particularly in terms of blue, which is only 4-6 percent efficient. This “zero power consumption for black” is a really nice story, but in practice, it’s not very useful since we don’t spend a lot of time looking at black screens. Screens with white backgrounds, like most of the web (i.e., Google), or e-book reading are much more challenging for OLED. QDEF is an LCD technology, so it relies on a backlight that stays on all the time. This sounds less efficient at first glance but QDEF is able to improve the efficiency of the system by tuning the spectrum of the light in the backlight to match the color filters. This means less wasted light because you are only generating light that you will see and much more color for the same amount of power input. Compare the iPhone 4 LCD and Nexus OLED display power consumption in Displaymate’s Shootout

Reliability and Lifespan

Nanosys spent a significant amount of time designing and testing QDEF to ensure it is of the highest quality and reliability. More than 100 patents have gone into the design of QDEF, and it has been tested to meet industry standard lifetimes for TV’s (ie, 50,000 hours or more). OLED has historically been limited by the performance of its blue component and the mismatch between red, green and blue lifetimes can lead to issues over the life of the display.

Brightness

QDEF displays are as bright as LCDs. In tests that Nanosys has conducted using QDEF in an iPad, we were able to match the iPad’s brightness without needing extra power.  OLED displays have to work harder to achieve the same level of brightness as LCD displays, which translates directly to higher power consumption.  In order to maintain the same level of brightness with a less efficient OLED display, the device can use a lot of power.

Size

QDEF’s manufacturing process scales very easily; it can be made as large as the very biggest LCDs on the market today. So while 55” was a big announcement for OLED at CES, QDEF is ready to enable better color at 65” and beyond- today.

PPI

QDEF is compatible with all LCD resolutions- i.e. 300+ ppi and above.

Contrast Ratio and Black Level

QDEF doesn’t affect the “black” level of LCD displays. That said, I give a lot of QDEF display demos and it’s not uncommon for people to say they think the contrast ratio is better with QDEF. I believe it may have something to do with the Helmholtz Kohlrousch or HK effect, which says that intensely saturated colors increase our perception of the brightness of that color. This means that images tend to ‘pop’ a little more than a meter reading might suggest they would. I’ll also add that I was at CEDIA this year and saw some newer LCD TVs with local dimming technology that had stunning blacks. In one demo, you could not tell which TV was on in a pitch dark room. So I think we’re getting to a point with state-of-the art LCDs where contrast ratio is less of a differentiator for OLED.

How have you overcome the problem of thermal stability normally associated with quantum dots?

Nanosys has invested about a decade of R&D into QDEF to ensure it is of the highest quality and reliability. More than 100 patents have gone into the design of QDEF, and it has been tested to meet industry standard lifetimes for TV’s (i.e., 50,000 hours or more).

From a manufacturing perspective, what is cost implication of modifying an existing production line with QDEF vs. building an entirely new production line for OLED?

A manufacturer will incur virtually no cost to switch to QDEF displays. They simply swap out the diffuser sheet they are currently using for a QDEF sheet and exchange the white YAG phosphor LEDs to cheaper blue LEDs. Everything else remains the same. For OLED, a manufacturer must invest hundreds of millions to build an entire new fab for a completely different technology.

What is the cost of a QDEF display vs. a comparable size OLED display?

Nanosys is aiming to deliver QDEF to the manufacturer on a cost neutral basis. We can do this because display makers will be able to use cheaper blue LEDs, offsetting the cost of QDEF. The final consumer pricing will ultimately be decided by the brands when they go to market. In terms of OLED, we’ve heard that the 55” panels everyone saw at CES this year will hit the market at around the $8,000 mark. Given that you can pick up a 65” LCD for less than half of that price, I think there will be a significant price advantage for QDEF even if brands decide to position it as a premium product relative to other LCDs.

When will commercial QDEF displays be available?

Nanosys has delivered thousands of square feet of QDEF to our customers in anticipation of scaling up production of commercial products in the very near future. We cannot speak to the schedule our customers hold for when and where those products will be available.

Why do I need a wider-gamut display on my TV when the best content I can get is limited to Rec.709?

When HD TVs first started rolling off assembly lines, there was very little HD content available but the market responded pretty quickly. The content creation pipeline from TV stations, to sports broadcasts, to Hollywood started to upgrade their capture capabilities to take advantage of the extra resolution. We also s saw “upscaling” DVD players right away. While these DVD players couldn’t make up new data, they could scale the image to fill the screen and make for an improved experience from the library of DVDs that you already owned and had potentially invested a lot in.

I think we’ll see something very similar with color. There are some great color ‘upscaling’ technologies that are starting to emerge that increase the saturation of your rec 709 content on the fly without blowing out flesh tones. So the red Ferrari in the car chase seen really pops but the main characters look just right.

Finally, Hollywood has been capturing film in high color gamut formats for years but have to throw much of it out in post-production in order to match the color performance of your TV. Producers are leaving the best color on the cutting room floor. Color movie film, for example, has much more color saturation than the rec 709 on a Blu-ray disc. This means Hollywood can go back to the vaults and remaster decades of content so that it looks like it looked on the big screen on your TV.

[Ed] Don't know what Rec. 709 is? See our previous article

What impact will high color gamut displays have for consumers at home?

High color displays will allow for consumers to enjoy more visceral, more impactful, and truer to life content. Current home TVs are only able to display 30 to 40 percent of the visual color spectrum, and mobile devices are only capable of displaying 20 to 30 percent. This means the user is missing a large component of the visual experience. High color performance displays will make our digital viewing experience of movies and videogames more lifelike. Filmmakers and video game developers will be able to more accurately bring their creative vision to life.

 

About Jeff

Jeff Yurek is the Product Marketing Manager at Nanosys, a Palo Alto, Calif. based advanced materials company. He develops long-term marketing and communications strategies for the company, and also handles day-to-day public relations, investor relations, and marketing communications. As Nanosys’ resident color expert, Jeff also manages the “dot color” blog and shares his insights on color quality and display technology.  Prior to joining Nanosys in 2009, Jeff worked as the Chief Engineer at a recording studio in the northeast and successfully developed audio engineering solutions for clients as diverse as Joe Perry of Aerosmith, CBS Records and Harmonix (makers of the RockBand video game).

 

 

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