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Do we need a high refresh rate LED screen???

REFRESH RATE is one of the main data on the specification sheet of an LED screen, do you really understand it? Does it matter?
info@doitvision.net, www.doitvision.com, 23rd, Mar, 2020

REFRESH RATE is a measure of how many times per second redraws the image on the screen. It is measured in Hertz which is commonly abbreviated as “Hz”.For example, a refresh rate of 1920Hz means the image is refreshed 1920 times in one second. Normally, people are confused with the frame rate(FPS or frames per second).

They are indeed very similar and both refer to the numbers of times a static image is displayed per second, but frame rate usually refer to the content itself whereas the refresh rate refer to the video signal or display.

Let’s focus on REFRESH RATE
Normally, we see on the datasheet of a LED screen, it shows 1920Hz or 3840Hz. Above 1920Hz we will consider as high refresh rate. which fits to most of the high-speed videos source.

Below with a picture showing a difference of the LED screens with low refresh & high refresh rate:

Do we need a high refresh rate LED screen??? 1

And in real application how bad a low refresh rate LED screen works as below.

Do we need a high refresh rate LED screen??? 2

Besides the flickering “Black scan lines”, low refresh rate also brings bad visual effects of:
1)Image & video trailing smear, looks like images tear off and unnatural transmitted

Do we need a high refresh rate LED screen??? 3

2)Showing “mosaics”, ghost effects and small blocks in different colors

Do we need a high refresh rate LED screen??? 4

3)Showing uneven color of small blocks and color is not pure white

Do we need a high refresh rate LED screen??? 5

Anyway, if the screen will not be shot by the camera, people will not see this differences by eyes.

How to increase the refresh rate?
1. Hardware, drive IC, adopting high refresh rate model
2. PCB design, change the scan mode, simply taking, use more quantity of the driver ic, increase the processing ability for the data buffering
3.Software, a good software like Novastar/Brompton will help a lot for the refresh rate

What driver IC we should use to get high refresh rate screen?
1.Commonly use, ICN2153, MBI5252, easily gets 3840Hz, but grayscale being affected by adjusting brightness

2.Better choice, MBI5153, ICND2055, with PWM. Not only getting high refresh rate, better grayscale. Adjusting the brightness, grayscale not affected.

Additionally, when checking the real refresh rate, we should use a DSLR Camera, use mechanical shutter to shot the screen taking pictures, set the shutter speed of 1000/2000/3000/4000 to see if there is “black scan lines”.

Do we need a high refresh rate LED screen??? 6

Do not only trust the number shows in the control software.
We found that in control software it shows 1920Hz, but with a DSLR camera, the real number is only 600Hz or even worse. The control system manufacturer plays marketing tricks on this numbers. Be in mind that, when selecting an LED screen with high refresh rate, a serious check on the PCB design, the use of driver IC are necessary.

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Kris Liang

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