The competition is shifting from past battles over image quality, screen thinness and so on, to energy efficiency, marking a dramatic change in liquid crystal display (LCD) television trends. We popped open one of the products leading this trend to take a closer look at the technologies used to slash power consumption.
New energy-efficient LCD TVs are hitting the shelves in large quantity in 2009. The TV accounts for about 10% of total power consumption in the home, and TV manufacturers recognizing that low-power products will be more competitive are engaged in an intense performance competition.
One of the LCD TVs at the cutting edge of the trend is the BRAVIA, from Sony Corp of Japan. The first model to have low power consumption emphasized as a key selling point was the KDL-32JE1, a 32-inch set released in July 2008. Power consumption was only 89W, a 34% reduction from the prior model, and Sony promoted the set as the "Number One power-saving model on the market by a wide margin." And in fact power consumption was dramatically lower than prior designs. The first 32-inch BRAVIA model, released in Oct 2005, drew 150W, while the 32-inch cathode ray tube (CRT) model of June 2000 drew 220W.
We picked up a Sony
KDL-32J5, a 32-inch set released in Feb 2009 as the successor to the
KDL-32JE1. The company claims this set's power consumption is 84W (max
luminance mode, all-white screen, max volume). Actual measurement of
terrestrial digital broadcasting in the standard mode was 56.45W (Fig
1).
We asked a few specialists, including engineers from TV and backlight manufacturers, to join us in disassembling the set to find out how Sony did it. We discovered that the whole Sony design concept was clearly built around slashing energy consumption. During the same disassembly session, we also took apart the DY-32SDDB LCD TV, a 32-inch set from Dynaconnective Co Ltd of Japan which is stirring up excitement because of its price tag of under Yen50,000.
No Conversion to DCWe discovered two power-saving techniques through our investigation, the first of which was evident as soon as we removed the back panel from the Sony 32-inch LCD TV: there were only two circuit boards (Fig 2).
One of the boards holds the power supply and backlight inverter circuitry, and the other is the signal processor. The engineer from the backlight manufacturer pointed out that most LCD TVs use separate boards for the power supply unit and the backlight inverter circuitry. This turned out to be the case in the Dynaconnective TV, in fact (Fig 6). The boards were integrated into one in the Sony set, though, and our suspicion is that this was done to improve power utilization efficiency.
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