Adjustment of LED screen brightness and full color RGB.

Many customers encounter some problems when using LED screens, and often ask how to adjust the brightness and color of the LED screen. After reading the detailed explanation below, I believe you will find the answer you want.
When manufacturing LED large screens, the first step is to select the LED display module according to the brightness index. Secondly, the brightness ratio of the selected product’s red, green, and blue colors is used to determine which color is the benchmark. Generally, the one with the lower brightness ratio is used as the brightness benchmark. When the benchmark has reached its maximum brightness, the other color (dual color) or two colors (full color) are adjusted.

When the display screen is dual color, in most cases, the working current of the red diode is adjusted based on green as the reference. Generally, the working current is reduced to balance the color yellow as the adjustment standard, which reduces the brightness of the entire display screen.
Adjusting the color of the display screen to the optimal balance state will reduce the brightness of the screen. If the display screen reaches the maximum brightness for each color in order to meet the brightness requirements, it loses color balance, for example, the yellow color of a dual color screen tends to be red or green.

The TTL output low level is about 0.4V. If used as a current input, the normal maximum input current is 35mA. When this current is exceeded, the output low level rises. As the current increases, the output low level continues to rise, indicating that the circuit still operates normally with an output voltage greater than 0.4V.
In the display scanning circuit, a working current of 20mA can meet the requirements for controlling the red color, as the brightness of the red LED is relatively high; The working current of green LED should be higher than 20mA, and the current should be between 30-50mA. At this time, the output voltage of 74HC595 also needs to increase. The reason is that 74HC595 has output resistance and is a non-linear change.
The scanning circuit operates in a dynamic scanning and static driving manner. The scanning frequency of LED display screens is limited by the structure of the display module. Each module has 8 x 8 LEDs, and the row data of the entire LED display module is connected in series. Updating the data once takes a longer time. When the scanning frequency is 100Hz, the brightness of the entire screen will decrease. If the scanning frequency of the screen is reduced, the display brightness will decrease. Experimental results have shown that the relationship between scanning frequency and color is relatively small.
After designing and analyzing the dual color LED screen, the technical parameters of the circuit were effectively adjusted, resulting in a relatively good display effect.
It has been proven that analyzing the technical characteristics of a circuit in a reasonable manner and keeping it in the optimal working state can achieve the desired display effect.