Unlike the commonly used electronic products that are viewed at close range, such as mobile phone screens, laptop screens, etc., LED displays are suitable for long-distance viewing. For the same LED screen product, the viewing distance will determine whether the display effect that the viewer sees is clear or not.
The theoretical resolution of the human eye is 20 arc seconds, but due to the distribution of photoreceptor cells and their own defects, the actual resolution of visible light is 1 arc minute, and objects wider than 1 arc minute are blended with the background.
For example, let’s calculate the “point distance limit” that the human eye can see at 1 meter. You can simply understand it as the smallest point diameter or the smallest straight line diameter that your eyes can see at 1 meter ( smaller than the above size, then they will dissolve into the background), or it can also be understood as the minimum distance that can separate two small points (line diameters), if it is smaller than the above distance, then they will dissolve into a point or a straight line.
1 arc minute = 1/60 degree = (2π/360) / 60 = 0.000291 radians Therefore, the minimum point distance that can be seen at 1 meter (approximately equal to the arc length): arc length = arc * radius = 0.000291*1000mm = 0.291 mm Now let’s do the actual calculation. Let’s use a 16:9 high-definition (resolution 1920×1080) flat-panel TV screen to illustrate:
1 meter distance corresponds to 25.237 inches
2 meters distance corresponds to 50 inches
3 meters distance corresponds to 75 inches
4 meters distance corresponds to 100 inches
5 meters distance corresponds to 125 inches
The reverse deduction of the formula is the formula for calculating the best viewing distance in terms of the viewing distance of the LED display.
The best viewing distance is defined as: in the normal direction of the front of the screen, the minimum distance between the two closest adjacent pixel light-emitting points cannot be distinguished. It means that you can watch high-definition images in the visible area greater than the optimal viewing distance. At this time, you will not feel the graininess of the screen, because the resolution limit of your eyes has been reached.
The resolution of the human eye mentioned above is 1 arc minute, which is obtained by testing the black bars on a white paper under very ideal conditions (sunny and bright enough, and no reflection), and it is obtained by people with particularly good eyes. In fact, the average person’s eyes are not that good, and the results will be biased if this experiment is done under dim light, the human eye is highly sensitive to this pattern, which will be 3 to 5 times more sensitive to the white dots on a black background.
In addition, for a point light source in the dark (if the brightness of the point light source is the same, for example, double star observation in astronomy), the resolution of the best person can reach 2 arc minutes, and the resolution of the average person in this case is 3- 5 cents. If the viewer is nearsighted, the resolution of distant objects will be lower.
Therefore, we calculate the ideal situation (according to greater than 1 angular minute), people standing in the area between S1 and S2 can watch all the images without losing information, and the best viewing distance is at the golden section point Sr. Perfect balance between distance and vision.
1 minute of arc＝1/60 degree＝(2π/360)/60＝0.000291 radian; usually take the value of 0.000294 radian, 1/0.000294=3400, get the formu
:
Minimum sight distance S1=3400H; whe
:
Maximum viewing distance S2=3400P; P(mm)——LED pixel pit
;
Optimum viewing distance Sr = 1+0.618(S2 -S1); H(mm)——three-color LED particle spaci
;
From this it can be deduced th
t:
The theoretical resolution of the human eye is 20 arc seconds, but due to the distribution of photoreceptor cells and their own defects, the actual resolution of visible light is 1 arc minute, and objects wider than 1 arc minute are blended with the backgrou
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