Refresh Rates

[Stiganator]

Here is my problem. I want a thin monitor. LCD's are the only thin monitor, so I check out the specs and I see like 8 different refresh rates. THe way I understand it LCD is ALWAYS faster than CRT in refresh. Correct me if I am wrong. Explain to me what to look for in a good LCD.


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[CTho9305]

I'm not sure what you mean by LCD refresh rates... but an important thing is response time - how quickly pixels can switch on/off. If it is too slow, you'll see major blurring/streaking in games.

 

[jthsmak]

pretty sure LCDs dont refresh top to bottom like CRTs.

 

[Gosharkss]

LCD monitors do NOT flicker like CRT monitors.

CRT monitors use an electron beam that scans the inside of the picture tube. On the inside face of the tube, red, green and blue phosphor dots emit light when struck by the electron beam. Once lit, the luminance of the phosphor starts to degrade until the beam comes back around to refresh it. This is known as the refresh rate.

LCD monitors use a matrix of cells 1024 x 768 for a 15?, 1280 x 1024 for an 18?. LCD monitors use a back light to create the luminance and is always on. Each cell has three transistors that let current flow through liquid crystal. One for red, one for blue and one for green. When the transistor is on, it allows light to pass. Think of it as a light valve. Colors are produced on LCD monitors using polarized filters. When the transistor turns on, it stays on, for the full cycle or refresh time, thus the amount of light output stays constant. No flicker no matter what the refresh rates.

 

[zephyrprime]

<< Correct me if I am wrong >>


You're wrong. LCD's usually have lower refresh rates than CRTs but the thing is, it doesn't matter. CRT's only need high refresh rates because they have relatively short phospor persistance. That is, after the pixel on a TV has been lit by the electron beam, it quickly becomes dim. So, to counteract the dimming, the electron beam has to come by light the pixel again many times per second.

On the other hand, modern LCDs monitors are active matrix LCDs have dedicated transisters that control the signal applied to each pixel at all times. So, LCD pixels don't dim and a high refresh rate is completely unnecessary. In the world of LCDs, high refresh rates are obsolete. The only thing is, you want a refresh rate that supplies enough frames per second to get smoothly animated gaming

I think 60 is enough but if you're a real stickler for smooth animation they go for a higher rate.

What matters far more than refresh rates for LCD quality is pixel switching speed. Look for something around 50ms. Higher values will give you the blurry/ghosty effect that LCDs exhibit when playing video or games. Actually, even 50ms isn't so great but unfortunately, current tech does not allow for much faster. (although that will change within the year as a new lcd technology that addresses this issue is released.)

Now the confucing thing is manufacturers usually link their fast switching speed lcds with higher refresh rates. Thus, a high refresh rate on a lcd will usually be an indicator for fast switching. Confusing!