Samsung, LG Debate on TV Refresh Rate
By Kim Yoo-chul
Staff Reporter
Improving picture quality for fast-moving scenes has been critical for LCD television makers, as the chief weakness of LCD screens is that they tend to blur when displaying motions.
Recently, makers have created televisions that have 240Hz refresh rates, which are four times faster than the screens used in most LCD televisions today.
However, there are debates whether the new models are worth the wait.
Refresh rates refer to how many times a frame is drawn each second, and although it's hard to question the difference between a 60Hz picture and a 240Hz picture, there are differing opinions on whether the difference is worth paying the premium for.
Now, a recent study by researchers at the University of California, San Diego (UCSD) claims that 240Hz televisions could indeed be a smarter buy than previously thought.
Televisions using 120Hz and 240Hz scans were shown to have distinctive differences in on-screen quality, the researchers said.
Clearly, Samsung Electronics, the world's largest television maker, would love to shove the report in the face of its bitter industry rival, LG Electronics, as it has been a chief backer of 240Hz televisions.
LG, on the other hand, had been claiming that 120Hz refresh rates coupled with scanning backlight technologies are just as good.
"120-Hz LCD TV with backlight scanning should not be referred as 240-Hz LCD TV to clarify the difference of the systems," Stanley H. Chan and Truong Q. Nguyen said in a study tilted "Comparisons of 240-Hz LCDs," which was recently submitted to the IEEE International Conference on Acoustics, Speech and Signal Processing.
Samsung and its Japanese rival Sony are the only two LCD television makers in the world to deliver 240Hz models.
LG, along with other makers such as Toshiba and Vizio, are using what some industry watchers claim as "pseudo" 240Hz, or flashing backlights behind 120Hz panels to achieve similar effects to a doubled refresh rate.
Although this technology provides a cheaper alternative for television makers, the UCSD researchers claim that pictures from true 240Hz televisions are definitely sharper.
True 240Hz LCD televisions currently require the use of two motion compensation-motion estimation (MCME) chips that help generate the interpolated frames used to enhance low frame rate video, and this also drives up the cost of the television sets.
On the other hand, pseudo 240Hz models use MCME chips to achieve 120Hz, but instead of doubling the interpolation, have backlights flash on and off at a rapid rate to achieve the "240Hz effect."
Despite the difference, LG has failed to make the distinction and continues to promote its televisions as though they were 240Hz models.
"A 120-Hz LCD TV should have liquid crystals with only 120-Hz response time. Therefore, the exponential decay function should fall slower than a 240-Hz liquid crystal," the study said.
An LG Electronics spokesman disagreed, saying, "LG's scanning-backlight method has completely eliminated the reason to cause blur images on screens as the technology is a 240Hz live scanning way to realize 240 frames per second."
He added that the complete elimination of blur images is more important than rate technology.
LG officials say its 240-Hz LCD TVs with scanning-backlight have sold over 90,000 units since their introduction in March.