Sommario
What's Led Display Brightness?
LED display is consisted by led lamp, hence the brightness of the led display is consisted by all led lamps’ brightness. The brightness unit is cd/m2 , hence the brightness of the led display can be calculated as below:
Brightness = Single pixel brightness * pixel pitch density of the led display
Pixel pitch density = 1000/pixel pitch * 1000/pixel pitch
While as the the pixel is consisted by red, green and blue led lamp. And each led lamp has its own brightness specs. So which specs should we use? Actually the brightness of the led display often refer to led display white balance brightness. To achieve white balance, the red light : green light : blue light ratio should be 3:6:1. Then from the led lamp’s spec we can know the maximum white brightness for single pixels.
single pixel maximum white brightness = min(red lamp brightness/3 , green lamp brightness/6, blue lamp brightness/1) *10
Now as most led display is using multi-pixel scan technology. Then the formula need to change as below:
Brightness = Single pixel brightness * pixel pitch density of the led display / Scan rate
Normally the led display would have mask to protect the led display or coating with glue, those would affect the light pass rate. Hence the formula need to change as below ( normally we take the light loss as 10%)
Brightness = Single pixel brightness * pixel pitch density of the led display / Scan rate * light remain rate
For example, in led lamp manufacturer’s website, we can have the led lamp’s spec data. Here we take Nationstar’s RS-1515MBAM for instance. You can find the spec sheet in this link: https://www.nationstar.com/en/goods/357.html
From the spec, we would know that Red lamp would output 55mcd brightness with 8mA current input, Green lamp would output 170mcd brightness with 5mA current input, and Blue lamp would output 17mcd with 3mA current input.
Then for a pixel pitch 1.875mm with 32scan rate, if using this lamp, this max brightness can be
Brightness = min(55/3,170/6,17)*10*284444/32/1000=1511cd/m2
The formula above is the theory of the brightness of the led display. On the condition that it did not exceed the power supplier’s loading ability, and the heat dissipation is good enough.
Led Screen Power Consumption
The power consumption of the led display is the sum up power consumption of every pixels. We assume that the brightness of the led lamp has a linear relation with the input current. From the led lamp’s specs above. and take pixel pitch 1.875mm, scan rate 32 for example.
Red lamp would output 55mcd brightness with 8mA current input,
Green lamp would output 170mcd brightness with 5mA current input,
Blue lamp would output 17mcd with 3mA current input.
And the Max white brightness for single pixel is min(55/3, 170/6,17)*10, Hence we would know the red led lamp would give 3*17 = 51mcd, green lamp would give 17*6 = 102mcd. then we would know
Red lamp’s current is 51/55*8 = 7.41mA
Green lamp’s current is 102/170*5 = 3mA
Blue lamp’s current is 3mA
As normally the power supplier’s voltage is 4.6V, Hence the wattage for single pixel is
single pixel wattage = 4.6*(7.41+3+3)=61.686mW
Then the total wattage = single pixel wattage * pixel density/scan rate = 61.686 * 284444/32/1000 = 548.32W/sqm
This is in theory, while as the power supplier only has around 80% efficiency, hence when you do the design you need to use 848.32/0.8 = 685.4W/sqm
High Brightness Led Screen
Outdoor and semi outdoor led display always need high brightness so that the screen can be readable under direct sunlight expose. Normally for semi-outdoor led display, the brightness need to be over 4500nit, For outdoor led display, especially for the led display that installed in highway sometimes need high brightness of over 10000nit.
Solutions of high brightness led screen
1: Increase the power supplier
2: Common cathode lamp solution
3: Using high brightness led lamp or gold wire led lamp
4: Use led lamp with lens
5: Increase the contrast ratio by using darker mask and lamp (you can find Xinying lamp in the link here with darker coating: https://en.sinyopto.com/product/108.html)
Solution of led display light pollution
Led display light pollution has become a problem especial for outdoor led display, as the outdoor led display need to have a high brightness under sunlight expose. But when it get dark, the high brightness of the led display becomes light pollution. So how to solve this?
1: We can use a ambient light sensor, that the led display’s brightness can change accordingly to the ambient light.
2: We can set a time table of different brightness setting for the led display.
We Tepixel offer customized turnkey solutions for different led display projects. from TV studio led display, Conference room led display, shopping mall led display to other kind of creative led display. Welcome to contact us for more informations
