You might have noticed a new spec in LCD TV ads recently: 240Hz. In an August 2 Best Buy circular, for instance, the promo copy for Sony's XBR9 LCD sets says: "240Hz gives you extra-clear fast-action movies and sports," and a pitch for Samsung's B8000 LCD sets says 240Hz makes "fast-action movies and sports look smoother and more precise."
240Hz is an extension of 120Hz technology, which has been touted for some time. Both are an attempt to address a traditional weakness of LCD sets—motion blur during fast-moving scenes. 120Hz technology, which doubles a TV’s usual 60Hz frame rate, is now common on all but the smallest and least expensive set. When implemented well, this frame doubling does minimize the appearance of motion blur on scenes with fast-moving action.
As you may have guessed, 240Hz takes it one step further. But not all 240Hz sets offer comparable anti-blurring reduction. That’s because there are two different approaches to 240Hz technology.
For example, some manufacturers, most notably Samsung and Sony, use "true" 240Hz technology that actually quadruples the TV's frame rate by inserting three extra interpolated video frames into the video stream. Others—including LG, Toshiba, and Vizio—combine a 120Hz refresh rate with a scanning, or flashing, backlight to achieve a 240Hz-like effect.
We've now tested enough LCD TV models to say that those sets that use "true" 240Hz technology are the most effective at minimizing motion blur, to the point where it's no longer a problem. In general, sets that use quasi-240Hz technology do offer an improvement over standard 120Hz technology, but fall short of the motion-blur reduction we've seen with true 240Hz sets.
On the model pages in our latest LCD TV Ratings (available to subscribers), we identify the type of 240Hz technology these sets employ. And in the Ratings themselves, under the "Frame Rate" box at the top of the listings, those sets with quasi-240Hz technology are identified with quotation marks ("240Hz") to differentiate them from true 240Hz sets.
Stay tuned for additional reports on anti-blur technologies as we review more sets with this feature. Hopefully, we’ll soon be able to discuss the effectiveness of these technologies by brand. —James K. Willcox