Several factors that lead to the inconsistency of the brightness of the full-color LED display

Many customers will encounter a problem: the brightness of the full-color LED display is inconsistent. Today, the editor will summarize the factors that cause the inconsistency of the brightness of the full-color display. 1. Full-color LED display drive components The drive components are generally constant current drive chips, such as MBl5026. These chips contain 16 constant current drive outputs, which can be used to set the current output value. The error of each output of the same chip is controlled within 3%, and the output error of different chips is controlled within 6%. 2. The light-emitting element of the full-color LED display screen is the LED light-emitting tube, and the brightness inconsistency is inevitable during the production process. However, the countermeasures taken by LED display manufacturers are to perform classification after the production is completed. The smaller the brightness difference between two adjacent levels, the better the consistency, but the lower the yield and the higher the inventory, the more serious it will cause. Therefore, all full-color LED display manufacturers control the brightness difference between two adjacent files at about 20%. It is normal for the brightness error of 25% between the pixels of the LED display to appear. If the LED tube used is not the same grade and type of product, the brightness error will rise to more than 40%. How to solve the color difference of LED electronic display? The first method: using the visual inertia of the human eye, the pulse width modulation method is used to achieve gray scale control, which is to periodically change the light pulse width (that is, the duty cycle), as long as the period of repeated lighting is short enough (that is, refresh The frequency is high enough), the human eye can't feel the luminous pixels shaking. Because pulse width modulation is more suitable for digital control, today when microcomputers are generally used to provide and indoor LED display content, almost all full-color LED displays use pulse width modulation to control gray levels. The second method is to change the current flowing through the full-color LED display. Generally, the continuous working current of the LED tube is about 20 mA. Except for the saturation of the red LED, the brightness of the other LEDs is basically proportional to the current flowing. .