Original video frames (1 and 2) at 60 frames per second, aren't enough to fill 120Hz and 240Hz LCDs. Duplicating the original frames is one method. Alternately, frames can be interpolated to fill the gaps. In this example, the TV's processor creates frame 1a from the difference between 1 and 2. This (along with 2a, 3a, etc.) makes up the difference between 60Hz video and 120Hz TVs.
(Credit: Geoffrey Morrison/CNET )
With 120Hz, 240Hz, and even 600Hz, refresh rate gets a lot of attention in the marketing of new HDTVs.
What it is and how it works is interesting, but why it exists is even more so. And it can have a profound effect on the picture quality of your HDTV.
Curious?
Let's start with the basics. Television is a series of images, shown rapidly enough that your brain sees it as motion.
In the US, our electricity runs at 60Hz, so it's only natural that our TVs run at the same rate (elsewhere, 50Hz is common). This is largely a holdover from the CRT days, but our entire system is based on it, so there's no use changing it.
What this means is that modern HDTVs show 60 images per second (60Hz).
Upping the frame rate A few years ago, LCDs hit the market with higher refresh rates. These started at 120Hz, though now you'll see 240Hz and beyond. In this case, higher is indeed better, but to understand why it's... [Read more]
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