Sony HDTV Technology: Highlights

Sony HDTV: 200 Hz - Theory
With 200 hertz, Sony hopes to continue its glorious reputation in the HDTV sector. In their European development center in Stuttgart, the Sony engineers tinkered with optimizing the system for liquid-crystal displays (LCDs) until 2008. This was supposed to eliminate the weaknesses - in particular, the frequent motion-blur - of LCDs that use older Sony HDTV technology. But 200-hertz doesn't achieve this alone: In comparison to those of early models, the liquid crystals in modern panels react much more quickly.

The so-called "Motionflow" system actually generates 200 frames per second. That's no easy task - TV channels (or video recorders) deliver just 25 frames per second. To complicate things further, the 25 pictures do not arrive intact, but as 50 "interlaced" images. The more-detailed explanation is that a TV camera divides an image into horizontal lines. First, it samples all of the odd-numbered lines - that is, the first, third, fifth, and so on. These lines form the first interlaced image. The second interlaced image consists of all the even-numbered lines - 2, 4, 6, and so on. Between the capturing of these two interlaced images, one 50th of a second has elapsed - a rolling football, for example, therefore appears at different positions in the first and second images.

On old CRT TVs, this so-called "interlacing" method poses no problems - the electron gun writes the image onto the phosphor layer in the same way as the camera supplies it. Liquid-crystal displays, on the other hand, write the complete image sequentially ("progressive") from the top of the screen to the bottom - the first line, crucially, is followed by the second.

Anyone who's ever watched videos on computer monitors (which are also progressive) will know the resulting problem: Edges of moving objects fray, and the picture is almost impossible to enjoy. So, regardless of whether an HDTV displays 50, 100, or 200 hertz, it must first remove the interlacing (in a process known as "de-interlacing"), and repair the frayed edges. Finding the appropriate calculations for all types of image is a fine art.

The 50 smoothed-out images now have to convert into 200 separate frames - Sony HDTV LCDs running at this frame rate must therefore generate artificial intermediate motion phases. The required process is called "motion interpolation" and means the TV's electronics must guess - in almost real-time - where a football will be, for example, between two frames. This is no major problem if the ball is rolling calmly across the grass. If, however, a player runs up and kicks it in the opposite direction, things get trickier for the 100- or 200-hz technology: On the one hand, the picture can no longer move in the old direction, and, on the other, the ball cannot be allowed to degrade into pixel noise - both of which are common faults in older TVs with motion interpolation.

Sony HDTV: 200 Hz - Quality
Enough of the theory: Televisions.com has already tried out Sony's latest 200-hertz kit in the KDL-40 Z 5500. We felt that with video-based material - sports, other TV broadcasts, or camcorder recordings - Sony's 200-hz produces fluid motion better than any similar system. With film material, however, the effects are less beneficial: The TV removes the typical movie judder that many home-theater fans enjoy. If you switch off 200-hz Motionflow, the movie appears blurry, instead of showing judder - other TVs can do this better. Put simply, Sony's 200-hertz Motionflow is ideal for sports fans, but movie fans should focus on other models.

Sony's Z5800 series, released this autumn, uses 200-hertz technology to give "the smoothest, sharpest fast-action scenes".

The 200-hertz Sony LCD TVs kick-started an arms race in the TV sector: 200-hz logos now adorn the brochures of many manufacturers. Almost all of the rivals, however, only generate 100 intermediate images and display black frames between them, in an attempt to improve contrast.

Televisions.com's tip for 200 Hz:
Customers shouldn't let themselves be impressed too much by big-sounding numbers: No single technology is responsible for producing a great picture; instead, the picture relies on the combination of many details, carefully tuned to one another. Even among TVs running at just 50 hertz, there are some excellent candidates - as well as, of course, mediocre ones. Still, you have to hand it to the Sony HDTV LCDs: Their 200-hz Motionflow is extremely sophisticated.

Sony HDTV: Local Dimming
Although Sony isn't the only company currently using this technology, it was one of the pioneers: Sony HDTV models began appearing with Local Dimming in 2008. This technology divides the screen into more than one hundred sectors, each of which is illuminated by light-emitting diodes that vary in intensity depending on the picture content in that area - independently of the other sectors. Dark sections of the picture are therefore supposed to appear a deep black - and not the milky gray frequently seen on other LCDs.

Currently, Sony only has two Local Dimming models in its selection: the KDL-55 X 4500 and the KDL-46 X 4500 (for details, see the model overview above). In the Televisions.com test, the KDL-55 X 4500 impressed - even many plasma TVs cannot conjure up as dark a black as this Sony LCD. For the last drop of perfection, however, the TV could do with more independent sectors: If the 55 X 4500 displays a starry night sky, for example, the screen once again looks gray.

Sony HDTV: Wireless HDMI
With the release of the EX series, also in 2008, we met the first Sony HDTV LCDs to use wireless transmission of all picture and sound signals to the screen. However fascinating the idea of a screen that needs nothing but a power cable might be, the picture quality failed to impress at Televisions.com.

A nice idea: Sony's EX1 series bundles all of the TV's connectivity into a separate box, which then communicates with the TV wirelessly - but it's a shame about the poor picture quality. Pictured here is the box from the Sony KDL-40 EX1.

The following were involved in producing this article on Sony HDTV technology:

Author(s): Karl-Gerhard Haas
Editor in Chief: Florian Friedrich
Photos: Manufacturers and AV T.O.P. Messtechnik GmbH
Last updated: September 2009