Like other items, LED display screens inevitably encounter problems and precautions of one kind or another in use. When using a full-color LED large screen, these eight problems may cause difficulties or affect the use of the large screen, and can extend its service life.
Heat dissipation design
LED will generate heat when it is working, and high temperature will affect the attenuation speed and stability of the LED. Therefore, the heat dissipation design of the PCB board and the ventilation and heat dissipation design of the cabinet will affect the performance of the LED.
Mixed lights
The LEDs of the same color and different brightness levels need to be mixed, or inserted according to the light insertion diagram designed according to the discrete law, to ensure the consistency of the brightness of each color on the entire screen. If there is a problem in this process, the local brightness of the large screen will be inconsistent, which will directly affect the display effect of the large LED screen.
LED display
Design current value
The nominal current of the LED is 20mA. Generally, it is recommended that the maximum use current be no more than 80 percent of the nominal value. Especially for large screens with small dot pitch, the current value should be lowered due to poor heat dissipation conditions. According to experience, due to the inconsistency of the attenuation speed of the red, green, and blue LEDs, the current value of the blue and green LEDs should be reduced in a targeted manner to maintain the consistency of the white balance after the large screen is used for a long time.
Drive circuit design
The arrangement of the driver IC on the driver circuit board on the large screen module will also affect the brightness of the LED. Since the output current of the driver IC is transmitted too far on the PCB board, the voltage drop of the transmission path will be too large, affecting the normal operating voltage of the LED and causing its brightness to decrease. We often find that the brightness of the LEDs around the large screen module is lower than in the middle, which is the reason. Therefore, to ensure the uniformity of the brightness of the large screen, it is necessary to design the driver circuit distribution diagram.
Control the verticality of the light
For in-line LEDs, there must be sufficient process technology to ensure that the LED is perpendicular to the PCB board when passing the furnace. Any deviation will affect the brightness consistency of the LED that has been set, and color blocks with inconsistent brightness will appear.
LED display
Welding control
When the LED is not bright on the large LED screen, there is often more than 50 percent probability that it is caused by various types of virtual soldering, such as LED pin soldering, IC pin soldering, pin header soldering, etc. The improvement of these problems needs to strictly improve the process and strengthen the quality inspection to solve. The vibration test before leaving the factory is also a good inspection method.
Wave soldering temperature and time
It is necessary to strictly control the temperature and time of wave front welding. The recommended preheating temperature is 100 degree ±5 degree , and the highest temperature should not exceed 120 degree , and the preheating temperature must rise smoothly. The welding temperature is 245 degree ±5 degree . It is recommended that the time should not exceed 3 seconds, and do not vibrate or shock the LED after the furnace, until it returns to normal temperature. The temperature parameters of the wave soldering machine should be checked regularly. This is determined by the characteristics of the LED. Overheating or fluctuating temperature will directly damage the LED or cause hidden quality problems, especially for small-sized round and oval LEDs such as 3mm.
anti-static
LED large screen assembly factories should have good anti-static measures. Dedicated anti-static ground, anti-static floor, anti-static soldering iron, anti-static table mat, anti-static ring, anti-static clothing, humidity control, equipment grounding (especially cutting machine), etc. are all basic requirements, and should be checked regularly with a static meter .
