Several customers have asked me recently about refresh rates on LCD TVs. They wanted to know if the extra cost for 120/240 Hz refresh rates is worth the money, would they see the difference.
The short answer is no, you won’t see an improvement. In fact, if you already have a TV with this feature, turn it off! The higher refresh rates just add annoying artifacts to the image. If I calibrate your LCD flat panel TV, I will turn off the higher refresh rate as a matter of course.
Why would the manufacturers of LCD TVs add a feature that makes the image worse? This goes back to the early days of LCD technology. The early liquid crystals used in video equipment had a very slow switching time. For relatively static images this was OK. For video, anything that changed or moved rapidly would appear to blur. The competitors to LCD used this as a knock against LCD TVs. (By the way, this applies to all the variants of LCD, like LCOS, D-ILA, etc.)
Over time, the technology of LCD improved to the point where the grey to grey switching times can now keep up with the 60 Hz video refresh rate of progressive scan TV. However the perception of LCD motion blur hung around, so the LCD TV companies added 120 Hz refresh rates as a gimmick. Now we have a feature war and 240 Hz refresh rate is available on some LCD TVs. Expect even higher refresh rates to follow!
The best reviews I have seen by the most professional reviewers on LCD TVs agree that this gimmick is a step backwards. Testing has shown that 60 Hz is more than fast enough to prevent the human eye from seeing motion blur. After all, refresh rate of film used in most movie theaters today is only 24 Hz, and that has been the industry standard. Do you see motion blur in a movie theater? Interlaced scan updates at 30 Hz (480i, 1080i) and this is what most HDTVs are driven with. Progressive scan is 60 Hz (480p, 720p, and 1080p) and no source material has a higher refresh rate.
So how does a TV get to 120 Hz or 240 Hz when the source material only has 30 Hz or 60 Hz? Where do the extra frames come from? A video processor in the TV interpolates or “guesses” at what video information should be in those extra frames. This is a very complex process and requires expensive hardware to accomplish effectively. A professional quality video processor that could do this would more than double the cost of an LCD TV! So the commodity grade video processors in massed produced LCD TVs use gimmicks and tricks to create these extra frames to keep the cost of the hardware down. Unfortunately they don’t do a very good job and the end result is an image that suffers from artifacts.
My recommendation is to compare other features to make your decision and ignore the refresh rate specification. If you do happen to buy a TV with higher refresh rates, be sure to turn that off in the Picture Menu. If your TV has a 24 Hz refresh rate, use that for watching movies on Blu-ray players that output 24 Hz. That way you get frame for frame what was on the original film and this will look better than the 2-3 pull down used to convert 24 Hz film to 60 Hz video.
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