Apple Files Patent For Hybrid OLED-QD Display Technology
The debate between display enthusiasts over OLED vs quantum dot technology as the future benchmark standard for television and mobile device picture quality might eventually be answered by Apple, if recent hybrid technology filed this week at the U.S. Patent and Trademark Office (USPTO) finds its way to market.
Apple is seeking to patent technology that melds the color and power-handling benefits of quantum dot technology with the fast response time and self-emissive nature of organic light emitting diode (OLED) technology, according to the USPTO documents first reported Thursday by website Apple Insider.
The concept is not unlike what executives with Samsung and quantum dot resource Nanosys have discussed as “electroluminescent quantum dot technology,” which is another way of saying self-emissive quantum dot technology.
This was once labeled QLED by now-defunct quantum dot developer QD Vision, but that company’s assets and the term have been acquired by Samsung. Interestingly, Apple’s patent application lists Jonathan Steckel, co-founder of QD Vision, as the lead on a list of the technology’s developers.
QLED now generically stands for “quantum dot light emitting diode” displays, and is more of an umbrella term for technologies that use quantum dots to create images.
Read more on Apple’s stab at hybrid OLED/quantum dot technology after the jump:
Making display jargon that much more impenetrable, Apple is naming this new hybrid technology: “Quantum Dot LED and OLED Integration for High Efficiency Displays.” It essentially fuses aspects of the QD and OLED technologies into a pixel group.
OLED display technology is notable for its superior black level characteristics that give images a deeper contrast ratio ranging from pure black to peak brightness levels surpassing 750 nits in current generation OLED TVs. This contributes to OLED’s rich color base. Quantum dots are spherical nano particles composed of various heavy metals that emit light when excited by an electrical charge. The size of the quantum dot determines the color wavelength it emits and the amount of photon stimulus it receives from the backlight determines the degree of brightness is gives off.
Quantum dots can receive a very high charge when excited by a light photon from a blue LED backlight without burning out or losing color vibrancy over long periods of time. Currently, quantum dots are encased in transparent films (or inside tiny cells) that are sandwiched inside an LCD panel stack to add color and brightness boosting characteristics. They also produce a large color volume with bright and pure saturated colors with very little white light diffusion. The QD film is placed between the LED backlight and LCD panel and color filters.
Unlike OLED technology, quantum dots currently do not give off their own light and are used in conjunction with the LED backlight to produce color and brightness rather than each individual pixel. However, various implementations that will apply QDs inside an LCD’s color filter are soon to appear from various manufacturers.
Because OLED screens are emissive, each individual pixel generates its own light source enabling brightness (or darkness) to be controlled from pure black to bright white by each pixel. This makes for highly accurate brightness levels with deep color and efficient power handling capability, which is ideal for battery powered mobile devices. However, OLED’s color volume isn’t as bright or as pure as new QD displays.
The downside to OLED technology is its higher cost to produce and difficulty to manufacture, particularly in very large screen sizes, although work is progressing on new inkjet printing systems that greatly improve OLED manufacturing efficiency over what is possible today.
Apple’s technology would use QDs that are self-emissive (or electroluminescent), instead of photoluminescent as they are in today’s LED-LCD TV screens. Light would be controllable at the pixel level instead of from the filter or backlight.
Apple’s technology is said to bring a number of advantages over current OLED technology, including peak brightness levels of up to 1,000 pixels per inch, longer life, better saturated greens, and still thinner displays. The technology would also have a response time that is closer to the speed of OLED displays, according to Apple Insider’s report.
Apple’s patent applications suggest that the technology still has some elements to work out in the mass production department, meaning that arrival of an Apple-made hybrid electroluminescent QD display in an Apple tablet, monitor or, perhaps, television might still be some time away, but the applications shows that Apple is very much in step with today’s cutting-edge display technologies for whatever products it might have in mind.
By Greg Tarr
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