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# LED display screen various parameters calculation method

Source： RUI JIN

2018-04-01 10:03:57

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LED display (LED panel): LED is a light emitting diode, the English abbreviation of light-emitting diodes, referred to as LED. It is a display mode that controls semiconductor light-emitting diodes. A flat panel display consists of a small number of LED module panels. Its approximate appearance is composed of a large number of light emitting diodes, usually red. Used to display text, graphics, images, animation, quotes, video, video signals and other information display screen.

First, the size of the display screen

1. Indoor display calculation
(1) Give the screen specific data (length, width, area).
a. Example: The specification of the screen to be made is a Φ5 (diameter of pixel) screen with a screen length of 5.8 meters and a width of 2.6 meters.
b. First of all, it is clear that the technical parameters of the Φ5 panel are 480×480 mm and the resolution of the cell board is 96×96. (The cell board specifications and resolutions of different manufacturers are inconsistent. We use the Rio Tinto cell board specification as Example) Resolution of the cell board resolution: 1 square Φ 5 screen pixels = 1000000 ÷ 5 ÷ 5 = 40000
Note: The 1000000 here is actually 1000×1000, 40000=200×200. That means there are 200 pixels in the length of 1000mm, then 480mm should have 480÷1000×200=96. So the resolution of the cell board is 96. ×96
c. Calculate the number of blocks used for the cell board. The number of panels used for screen length or width = the length or width of pre-made screens or wide-width unit boards; the number of boards used for screen length: 5.8 meters × 1000 ÷ 480 = 12.08 ≈ 12
The number of panels used for screen width: 2.6 meters × 1000 ÷ 480 = 5.41 ≈ 5
d. Calculate the actual screen size.
Actual screen length or width = length or width of the cell plate × screen length or width
Actual screen length: 480×12=5760mm or 5.760 meters Actual screen width: 480×5=2400mm or 2.4 meters e. Screen area: 5.760×2.4=13.824 (square meter)
Note: Usually, the size of the screen outside the screen is 5-10cm on each side based on the screen size.
f. Resolution of the screen = number of screens used × resolution of the unit board
Screen resolution = (12 × 5) × (96 × 96)
(2) Only the area of the screen is given, there is no length and width.
a. Example: To make a screen with an area of 9m2, the screen size is Φ5 (the diameter of the pixel).
b. If we only give the area, we have to count ourselves. It can be calculated as a ratio of 4:3 or 16:9 in length and width. This is a good picture. This is because the ratio of 4:3, 16:9 can directly broadcast television signals, with a 4:3 approximately square display and a 16:9 approximately rectangular display. (here 4:3 as an example)
c. The theoretical screen length is: length = square root of area ÷12 × 4 width = square root of area ÷12 × 3: length = 3.46m width = 2.60m
d. The length and width have been calculated. For the calculations below, see the example in (1).

2. Outdoor display calculation
(1) Give the screen specific data (length, width, area).
a. Example: To do P20 outdoor full color screen about 10 meters long, about 6 meters wide
b. First of all, the specification of the unit box (length and width of the box) is 1280 x 960mm and the resolution is 64 x 48.
c. Calculate the number of boxes.
Screen length or width of the box = pre-screen length or width of the unit box length or width
Number of cabinets for screen length: 10 meters × 1000 ÷ 1280 = 7.8123 ≈ 8
Number of cabinets for screen width: 6m×1000÷960=6.25≈6
d. Calculate the actual screen size.
Actual screen length or width = box (size) length or width × screen length or width of box
Actual screen length: 1280×8=10240mm or 10.24 meters
Actual screen width: 960×6=5760mm or 5.76 meters
e. The area of the screen: 10.24 x 5.76 = 158.9824 ≈ 158.98 (square meters)
f. Resolution of the screen = resolution of the box X width × width of the box box = (64 × 10) × (48 × 6)
(2) Only the area of the screen is given, there is no length and width.
a. Example: If you are a P20, the outdoor full color screen area is about 50 square meters.
b. If we only give the area, we have to count ourselves. It can be calculated as a ratio of 4:3 or 16:9 in length and width. This is a good picture. (here 4:3 as an example)
c. The theoretical screen length is: length = square root of area ÷ 12 × 4 width = square root of area ÷ 12 × 3 ie: length = 8.16m width = 6.12m
d. Approximate the length and width to find, the following calculation reference example (1).

Second, the formula for the current of the cell board is as follows

Cell Current = (Cell Total Pixels * Number of LEDs per Pixel * Individual LED Current Size / Number of Scans) Single LED Current Size Typically 0.005 to 0.02, typically 0.01 A Scan Number General Indoor 16 Scan Semi-outdoors are 8 sweeps or 16 sweeps. Outdoors are usually 4 sweeps, 2 sweeps, or static sweeps.
For example, if a 5.0 dual-color indoor unit board is full (fully lit), the total number of point streams is:
(32*64)*2*0.01/16=2.56 A
In other words, 40A power supply can take: 40/2.56 = 16 blocks
One square meter, power consumption is: 2.56A * 5V / (0.488 long * 0.244 high) = 107 watts / square meter
However, some LEDs may need to be calculated with a current of 0.02A or even higher, which will result in greater power consumption. This board has a slightly higher brightness but is very hot, burns out easily, and the lamp can quickly age. This is a very bad design. I hope you have not bought such a unit board.
For example, outdoor 4 sweep full color (2 red 1 green 1 blue) 8 * 16 dot matrix unit module, the current is:
(8*16)*4*0.015 /4=1.92A
In other words, 40A power supply can take: 40/1.92 = 21 blocks
One square meter, power consumption is: 1.92A*5V/(0.256 long * 0.128 high) = 292W/square meter
The approximate current of the luminous tube is selected here to be 0.015A because some pure green and blue luminous tubes have special currents. Moreover, because of the color matching problem, it is only possible to roughly estimate that the starting instantaneous current is about 1.5 times that during normal operation.

Third, the display screen brightness calculation method
Take a full-color screen as an example, usually the red, green and blue-white balance ratio is 3:4:1.
Red LED brightness: Brightness (CD)/M2 number of dots/M2×0.3 (white balance ratio is 30%) ÷2 Green LED brightness: Brightness (CD)/M2 / points/M2×0.6 (White balance ratio 60%) Blue LED Brightness: Brightness (CD)/M2/M2×0.1 (White Balance 10%)

(1) Known full-screen brightness for single tube brightness
For example, if the density is 2500 points per square meter, 2R1G1B, and the brightness requirement per square meter is 5000 cd/m2, then:
The brightness of the red LED lamp is: 5000÷2500×0.3÷2=0.3cd=300mcd The brightness of the green LED lamp is: 5000÷2500×0.6=1.2cd=1200mcd The brightness of the blue LED lamp is: 5000÷2500×0.1=0.2cd= The brightness of each pixel of 200mcd is: 0.3×2+1.2+0.2=2.0 cd=2000mcd

(2) It is known that the brightness of a single tube determines the brightness of the entire screen
For example: P31.25, Japan and Asia as an example.
HSM display main die specifications
Red
green
HSM-PH-A+ (Nichia)
180-440mcd
1020-2400 mcd
Because the white balance with the brightness ratio of red: green: blue = 3:6:1; the ratio of white balance with the green tube to match other tubes. So as follows:
From red:green=3:6, the brightness of the green tube is 2 times that of the red tube.
That is, the brightness of the red tube is: 2400 (blue) ÷ 2 = 1200mcd. Since the red, green, and blue four tubes, the red tube has two, so the brightness of a single red tube is: 1200 ÷ 2 = 600 mcd.
From green:blue = 6:1, the green tube is 6 times brighter than the blue tube.
That is, the brightness of the blue tube is: 2400 (blue) ÷ 6 = 400mcd, 1 luminescent pixel = 2 red tube + 1 green tube + 1 blue tube;
That is, the brightness of one pixel = 600 (red) × 2+2400 (green) + 400 (blue) = 3400 mcd = 3.4 cd/m2 brightness = brightness of a luminescent pixel × pixel density per square meter (number) = 3.4cd x 1024 (number of pixels) = 3482 cd. Calculated by 20% light loss, the actual luminous brightness should be: 27885.28 cd.

Fourth, length and height calculation method

Point spacing × number of points = long/high
Such as: PH16 length = 16 points × 1.6cm = 25.6cm Height = 8 points × 1.6cm = 12.8cm
PH10 length = 32 points × 1.0cm = 32cm height = 16 points × 1.0cm = 16cm;

Five, point spacing calculation method

The distance from the center of each pixel to each adjacent pixel;
Each pixel can be a LED light [eg PH10(1R)],
Two LED lights [such as: PH16 (2R)], three led lights [such as: PH16 (2R1G1B)],
The pitch of P16 is: 16MM; the pitch of P20 is: 20MM; the pitch of P12 is: 12MM

Sixth, LED display resolution calculation method

LED display resolution per squared = 1/pixel pitch (units of M)/pixel pitch (units of M)
For example: P16 per square resolution = 1/0.016/0.016 = 3906 DOT (dot)

Seven, LED display visual distance calculation method

RGB color mixing distance Trichromatic mixing to a single color distance:
LED full-color viewing distance = pixel pitch (mm) × 500/1000
The smallest viewing distance can show the distance of the smooth image:
LED display visible distance = pixel pitch (mm) × 1000/1000
The most suitable viewing distance can be seen by the viewer:
The best viewing distance of LED display = pixel pitch (mm) × 3000/1000
The farthest viewing distance:
LED display distance of the maximum distance = screen height (m) × 30 (times)

Eight, screen body module number calculation method

Total area ÷ Module length ÷ Module height = Number of modules used
Such as: 10 squares of PH16 outdoor monochrome LED display using the number of modules equal to:
10 square meters ÷ 0.256 meters ÷ 0.128 meters = 305.17678 ≈ 305
More accurate calculation method: length of use module number * height of use module number = total number of modules used
Such as: 5 meters long, 2 meters high PH16 monochrome led display module number:
Long use module number = 5 meters ÷ 0.256 meters = 19.5325 ≈ 20
High use module number = 2 meters ÷ 0.128 meters = 15.625 ≈ 16 pieces
Total number of modules used = 20 x 16 = 320

Nine, the LED display's perspective depends on the choice of LED lamp beads

Such as indoor surface mount lamps: SMD0603/0805:H:160 degrees V:120 degrees
SMD3528 viewing angle: H: 140 degrees V: 120 degrees
Outdoor plug-in lamp DIP: dip346/546: H: 110 degrees V: 50 degrees
LED luminous tube wavelength range:
Red: 625-630nm
Yellow-green: 568-572nm
Pure green: 520-530nm
Blue: 460-470nm
Yellow: 585-590nm led display calculation method | led electronic display power calculation | led power calculation method
The general brightness requirements are as follows:
(1) Indoor:>800CD/M2
(2) Semi-indoor: >2000CD/M2
(3) Outdoors (South facing north): >4000CD/M2
(4) Outdoors (facing south): >8000 CD/M2

Ten, red, green and blue in the white brightness requirements

The contribution of red, green, and blue in white color quality is not the same. The underlying reason is that the retinal membrane of the human eye causes different perceptions of light at different wavelengths. After a large number of experimental tests, the following approximate ratio is obtained for reference
Test design:
Simple red, green and blue brightness ratio: 3:6:1
Accurate red, green and blue brightness ratio: 3.0:5.9:1.1
What is the ratio of the length and width of the display?
Graphic screen: Determined according to the displayed content;
Video screen: generally 4:3 or close to 4:3; ideal ratio is 16:9.

Eleven, LED display screen scanning method

Scan mode: the ratio of the number of rows lit at the same time and the number of rows in the entire area within a certain display area.
Indoor single and double color is generally 1/16 scan,
Indoor full color is generally 1/8 scan,
Outdoor single color is generally 1/4 scan,
Outdoor full color is generally a static scan.
At present, the LED display screens in the market are static scanning and dynamic scanning. Static scanning is divided into static real pixels and static virtual. Dynamic scanning is also divided into dynamic real images and dynamic virtual; drive devices are generally made in China HC595, Taiwan MBI5026 Toshiba TB62726, generally has 1/2 sweep, 1/4 sweep, 1/8 sweep, 1/16 sweep.

Give a description:

A commonly used full-color module pixel is 16*8 (2R1G1B). If MBI5026 is used for driving, the module uses a total of:
16*8*(2+1+1)=512, MBI5026 is a 16-bit chip, 512/16=32
(1) If 32 MBI5026 chips are used, static virtual
(2) If 16 MBI5026 chips are used, dynamic 1/2 scan virtual
(3) If 8 MBI5026 chips are used, it is dynamic 1/4 sweep virtual
If there are two red lights on the board
(4) With 24 MBI5026 chips, static real pixels
(5) With 12 M