For CRT displays, the electron beam is scanned point by point from the upper left corner of the screen to the right, forming a horizontal line: "knife up to the right end" and then back to the left end of the next horizontal line, repeating the process above: when the beam completes scanning at the lower right corner, a frame is formed. Thereafter, the electron beam returns to the starting point in the upper left corner to start the next scan. This method is also known as a progressive scan display. The completion of a frame of the time spent on the countdown called vertical scan frequency, also known as the refresh frequency (i.e. field frequency), such as 60Hz, 75Hz, etc. The greater the refresh rate, the greater the screen. The greater the refresh rate, the less likely the screen flicker, if the refresh rate is above 75Hz, the user is not easy to feel the screen flicker.

For the LCD, because of its working principle and CRT display is completely different, LCD is not like CRT display to launch the electron beam, there is no need to set the refresh rate indicators, but the output signal of the graphics card and the refresh rate of the signal, so LCD manufacturers in order to compatible with the graphics card, had to set a refresh rate indicators.

The graphics card can be compared to the human brain, the LCD compared to the human hands and feet, LCD is very mechanical, the graphics card let it do what it does, the graphics card output a 60Hz refresh rate signal, LCD will also do the same. In fact, the LCD refresh is not a single pixel, but the whole screen, this refresh is actually meaningless, even if the LCD refresh rate is working at 1 Hz also does not matter, the picture and work at 60Hz are the same. This is also why the LCD refresh rate is king in 60Hz and works in 75Hz feel the same reason. Perhaps only when CRTs are completely obsolete, LCDs and graphics cards will have no refresh rate specifications.

Some may ask: most of the LCD at 60Hz refresh rate can achieve the best picture quality, why not lock the refresh rate at 60Hz, but to have 60 ~ 75Hz selection range? In fact, this is related to the use of flexibility and compatibility issues. As the LCD trying to replace the CRT monitor market position, and most of today's graphics cards are still designed to CRT monitors, higher flexibility and compatibility will help LCD cut into and quickly capture the market.

There may be some people who will ask: why my LCD refresh rate when working at 60Hz and working at 75Hz when the picture will be very different? The LCD is only in the analog refresh, but it is also true that at 15 times per second to refresh the entire screen, when the LCD can not withstand the 75Hz refresh rate signal, the picture will be blurred. At this point, you should set the graphics card's refresh rate at 60Hz, a refresh rate that any LCD can withstand.

60Hz refresh rate and 75Hz refresh rate is no difference, why must the refresh rate set high? In fact, the important indicator of LCD is the response time rather than the refresh rate, LCD manufacturer's propaganda, all say how fast the response time, not how high the refresh rate. Therefore, the refresh rate is not LCD's main performance indicators.

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The refresh rate of TFT liquid crystal display