Like other items, led display screens will inevitably encounter problems and precautions of one kind or another during use. When using a full-color LED large screen, there may be eight problems that may cause difficulties or affect the use of the large screen and prolong its service life.
1. Thermal design
LEDs generate heat during operation, and excessive temperature will affect the attenuation speed and stability of LEDs. 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 LEDs. the
2. Mixed lights
LEDs of the same color with different brightness levels need to be mixed, or inserted according to a discrete pattern designed to ensure the consistency of the brightness of each color on the entire screen. If there is a problem in this process, there will be inconsistent local brightness of the large screen, which will directly affect the display effect of the LED large screen.
3. Design current value
The nominal current of the LED is 20mA, and it is generally recommended that the maximum operating current should not exceed 80% of the nominal value. Especially for large screens with small dot pitches, the current value should be reduced due to poor heat dissipation conditions. According to experience, due to the inconsistency of the attenuation speed of 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.
4. Drive circuit design
The layout 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 over a long distance on the PCB, the voltage drop of the transmission path will be too large, which will affect the normal working voltage of the LED and reduce its brightness. We often find that the LED brightness around the large screen module is lower than that in the middle, which is the reason. Therefore, in order to ensure the consistency of the brightness of the large screen, it is necessary to design the distribution diagram of the driving circuit.
5. Control the verticality of the lamp
For in-line LEDs, there must be sufficient process technology to ensure that the LEDs are perpendicular to the PCB board during the furnace. Any deviation will affect the brightness consistency of the LEDs that have been set, and color blocks with inconsistent brightness will appear.
6. False welding control
When the led screen does not light up, there is a probability of more than 50% that it is caused by various types of solder joints, such as solder joints of LED pins, IC pins, pin headers, etc. The improvement of these problems needs to be solved by strictly improving the process and strengthening the quality inspection. The vibration test before leaving the factory is also a good inspection method.
7. Temperature and time of wave soldering
The temperature and furnace passing time of wave front welding must be strictly controlled. The suggestion is: the preheating temperature is 100°C±5°C, the maximum is not more than 120°C, and the rise of the preheating temperature is required to be stable. It is recommended that the time should not exceed 3 seconds. Do not vibrate or impact the LED after the furnace is over until it returns to normal temperature. The temperature parameters of the wave soldering machine should be checked regularly, which is determined by the characteristics of the led video wall design. Overheating or fluctuating temperature will directly damage the LED or cause hidden dangers to the quality of the LED, especially for small-sized round and oval LEDs such as 3mm.
8. Anti-static
The LED large screen assembly factory should have good anti-static measures. Special anti-static floor, anti-static floor, anti-static soldering iron, anti-static table mat, anti-static ring, anti-static clothing, humidity control, equipment grounding (especially the cutting machine), etc. .
