LG's 240Hz LCDs flash backlights really fast

The least-expensive models of LCD in LG's 2009 lineup with a 240Hz refresh rate, the LH55 series utilizes a scanning backlight to get the extra Hz.

David Katzmaier Editorial Director -- Personal Tech
David reviews TVs and leads the Personal Tech team at CNET, covering mobile, software, computing, streaming and home entertainment. We provide helpful, expert reviews, advice and videos on what gadget or service to buy and how to get the most out of it.
Expertise A 20-year CNET veteran, David has been reviewing TVs since the days of CRT, rear-projection and plasma. Prior to CNET he worked at Sound & Vision magazine and eTown.com. He is known to two people on Twitter as the Cormac McCarthy of consumer electronics. Credentials
  • Although still awaiting his Oscar for Best Picture Reviewer, David does hold certifications from the Imaging Science Foundation and the National Institutes of Standards and Technology on display calibration and evaluation.
David Katzmaier
2 min read

LG's LH55 lineup features 240Hz with scanning backlight technology. LG

Now that 240Hz technology is appearing in TVs from most major manufacturers at CES, LG is interested in touting its own version, a so-called scanning backlight that, according to the company, outperforms other 240Hz methods.

The four-model LH55 series, LG's baseline 240Hz models, includes the 37-inch 37LH55, the 42-inch 42LH55, the 47-inch 47LH55 and the 55-inch 55LH55. The 37-inch set is the smallest 240Hz model we've hard of so far. They will ship in March, although pricing wasn't announced.

Compared with standard 120Hz LCDs, 240Hz models supposedly deliver smoother images and even better motion blur reduction. We've only tested one such TV so far, the Sony KDL-52XBR7, and it did indeed produce less motion blur, according to test patterns. As usual, however, the difference was nearly impossible to spot compared with normal 120Hz models with standard program material.

LG first introduced me to its scanning backlight technology at a private demo in December, where it compared a so-equipped LG model directly with the Sony. I found it difficult to tell the difference once the TVs were comparably adjusted, but that was with LG's test patterns and setup. I'll perform a more thorough evaluation once I have some comparable models in the lab, but at first sniff, the two 240Hz technologies seem to produce very similar results.

That doesn't stop LG from taking pains to differentiate its scanning backlights, which is the same method used by Vizio and Toshiba. According to LG, the system improves upon the so-called MEMC system used by Sony and Samsung because it requires fewer processing steps. LG's backlight flashes on and off extremely quickly, whereas the MEMC system achieves 240Hz the old-fashioned way: by interpolating three frames from the single frames on the 60Hz source material. The latter, according to LG, requires two processing boards, uses more power and is less cost-effective.

Like most LG HDTVs these models offer extensive picture controls, including the same 10-point IRE system and full color management controls we liked on the company's 2008 models. A new "picture wizard" is available as well, which employs a series of onscreen test patterns to ease user calibration. LG points out the power saving capabilities of LED technology, and the LH90 series also offers a "smart" room lighting sensor that also helps improve efficiency and automatically adjust the picture.

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