Sony KDL-55W900A 3D LCD HDTV Triluminos A New Breakthrough?
In 2009 Sony used the term Triluminos to refer to its first red, green, and blue LED backlit displays. It dropped the term somewhere on the road to 2013 (as it minimized but did not entirely eliminate its expensive-to-produce, fullarray LED backlit designs). But now it’s back, though today it refers to something quite different than mere tricolor LED backlighting.
Working with a company called QD Vision, Sony this year has incorporated that firm’s trademarked term Color IQ into its premium sets. Rather than using a full array of three-color LED clusters behind the screen, it uses edge-lit LEDs of a certain bandwidth to energize elements called quantum dots (the QD in QD Vision).
What are quantum dots? According to a ScienceDaily article, “A quantum dot is a semiconductor nanostructure that confines the motion of conduction band electrons, valence band holes, or excitons (bound pairs of conduction band electrons and valence band holes) in all three spatial directions.”
Got that? Neither do I. Put more simply, a quantum dot is an inorganic particle, millionths of a millimeter—or nanometers—in diameter, that emits light of a specific wavelength when energized. The actual wavelength depends on the size of the dot. In the KDL-55W900A, blue light from LEDs at the edges of the screen energizes the quantum dots, which are sized to emit either red or green light. Together with the blue LEDs, this produces the tricolored light required to illuminate the LCD panel.
While this may be a new way to generate backlighting (or more accurately in this case, edge lighting), this is still an LCD set. It’s the pixels in the LCD panel, not the quantum dots, that produce the actual image.
So what is the advantage of using quantum dots instead of using a display with red, green, and blue LED back or edge lighting? According to promotional material from Sony and QD Vision, it’s a wider range of colors—as much as 70 percent wider than the NTSC standard.
We’ve heard this song before, and most HDTV makers know the words and music by heart. But the verse they won’t sing addresses the fact that the NTSC standard to which they are referring, Rec. 709 for HD, is the standard in which all consumer HD source material, apart from some content from personal video cameras, are mastered. If you reproduce current consumer sources in a wider range of colors than Rec. 709 offers, you are simply distorting the source.
Sony recently announced, however, that it plans to release new Blu-rays encoded with xvYCC, a defined color extension to the HD standard that has been languishing in the wings for nearly a decade. The added xvYCC color information will be encoded separately on the disc and will be ignored by most sets. But in a set that can respond to it—including this KDL-55W900A—you will see a wider range of color that is, in theory, still true to the studio master. Much will depend, of course, on how accurately the xvYCC disc is mastered and how precisely the set decodes this new material. These new discs were not available to us at press time, but stay tuned!—TJN