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Response Time: 120Hz

What about 120Hz then? Subjectively, RTC artifacts disappeared when I changed the refresh rate, but why?

The response time does not change much. The average is 3.3 milliseconds (GtG), which is only 0.1 less than at 60Hz. This difference may be just due to measurement inaccuracies.

The RTC error in percent is somewhat lower: an average of 7.3% and a maximum of 40%. This is better than at 60Hz but not much different.

The RTC error relaxation time is the answer. The diagram is made to the same scale as for the 60Hz refresh rate so that you could easily see the difference. The average relaxation time was 15.2 milliseconds but now is only 6.6 milliseconds. It means that the RTC errors are not just lower but also vanish from the screen faster!

I want to illustrate this with a series of pictures showing the movement of a black square along a gray background at 60Hz and 120Hz refresh rates. The square is moving from left to right and its movement is captured each 8.3 milliseconds – the picture update period at a refresh rate of 120Hz.

When the square moves to a new position, there is a bright spot in its previous position due to the error of the too aggressively configured RTC mechanism. The next frame forces this spot to disappear (let’s assume, to disappear fully, although this is not always so in practice), but as the square has already moved again, there appears a new bright spot in a new position. Therefore, there is always a white trail (RTC artifact) following the square.

Now take note that the interval between the two positions of the square is twice smaller at 120Hz than at 60Hz. Thus, the square moves by only half the distance, and the bright spot is only half the width!

And as I have found out in my test, the white spot also disappears quicker at 120Hz. As a result, the perceptible intensity of the artifacts is lowered not two but fourfold!

I won’t claim that this effect will be seen on all 120Hz monitors (hopefully, there will be more of them soon), but the SyncMaster 2233RZ shows what benefits the new technology can provide even without any stereo glasses.

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