|Use tips of LEDs for full color display video panels|
A good method of use and environment is also very important for the long-term maintenance of high-quality LEDs:
The display assembly factory should have good anti-static measures. Special anti-static grounding, anti-static floor, anti-static soldering iron, anti-static mat, anti-static ring, anti-static clothing, humidity control, equipment grounding (especially cutting machine) are basic requirements, and should be regularly tested by static electricity meter. .
2, wave soldering temperature and time
The temperature of the wave front welding and the furnace time must be strictly controlled. The recommended temperature is: preheating temperature 100 °C ± 5 °C, maximum not exceeding 120 °C, and the preheating temperature rise is required to be stable, the welding temperature is 245 °C ± 5 °C, welding The time is recommended not to exceed 3 seconds. After the furnace is over, avoid vibrating or impacting the LED until it returns to normal temperature. The temperature parameters of the wave soldering machine should be regularly checked. This is determined by the characteristics of the LED. Overheating or fluctuating temperature will directly damage the LED or cause LED quality hazard, especially for small and thin LEDs such as 3mm.
3, design current value
The nominal current of the LED is 20mA. It is generally recommended that the maximum current used is not more than 80% of the nominal value. Especially for displays with small dot pitch, the current value should be reduced due to poor heat dissipation conditions. According to experience, due to the inconsistency of the red, green and blue LED attenuation speed, the current values of the blue and green LEDs are specifically reduced to maintain the consistency of the white balance after the display is used for a long time.
4, mixed lights
LEDs of the same color with different brightness levels need to be mixed with lights, or inserted into the light pattern according to the discrete pattern to ensure the consistency of the brightness of each color of the whole screen. If there is a problem in this process, the local brightness of the display will be inconsistent, which will directly affect the display effect of the LED display factory.
5, control the verticality of the lamp
For in-line LEDs, there must be enough process technology to ensure that the LEDs are perpendicular to the PCB. Any deviation will affect the brightness consistency of the already set LEDs, and the color blocks with inconsistent brightness will appear.
6, heat dissipation design
When the LED works, it will generate heat. If the temperature is too high, it 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.
7, virtual welding control
When the LED display does not light up, there are often more than 50% probability of various types of virtual soldering, such as LED pin soldering, IC pin soldering, pin rowing and soldering. Improvements in these problems require rigorous improvements in the process and enhanced quality inspections. The vibration test before leaving the factory is also a good test method.
8, drive circuit design
The arrangement of the driver board drivers on the display module also affects the brightness of the LEDs. Since the output current of the driver is too far away on the PCB, the voltage drop of the transmission path is too large, which affects the normal operating voltage of the LED and causes its brightness to decrease. We often find that the brightness of the LEDs around the display module is lower than the middle, which is why. Therefore, to ensure the consistency of the display brightness, it is necessary to design the drive circuit distribution map.