Matters needing attention in the use of full-color LED display

Like other items, full-color LED displays inevitably encounter problems and precautions during use:

1. Anti-static

Full color LED display 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 foot-cutting machine), etc. are basic requirements, and should be regularly tested with an electrostatic meter .

2. Design current value

The nominal current of the LED is 20mA. It is generally recommended that the maximum current of the LED should not exceed 80% of the nominal value. Especially for the display screen with a small dot pitch, the current value should be reduced due to poor heat dissipation conditions. According to experience, due to the inconsistency of the attenuation rate of the red, green, and blue LEDs, the current value of the blue and green LEDs is targeted to reduce the consistency of the white balance after the display is used for a long time.

3. Heat dissipation design

LEDs will generate heat during operation. Excessive temperature will affect the attenuation rate 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.

4. Drive circuit design

The arrangement of the driver ICs on the driver circuit board on the display module will also affect the brightness of the LED. Because the transmission distance of the driver IC output current on the PCB board is too far, the transmission path voltage drop will be too large, affecting the normal working voltage of the LED and causing its brightness to decrease. We often find that the LED brightness around the display module is lower than the middle, which is the reason. Therefore, to ensure the consistency of the brightness of the display screen, it is necessary to design a distribution diagram of the driving circuit.

5. Mixed lights

LEDs with different brightness files of the same color need to be mixed, or inserted according to the light insertion diagram designed by the discrete law to ensure the consistency of the brightness of each color of the entire screen. If there is a problem in this process, the local brightness of the display screen will be inconsistent, which directly affects the display effect of the LED display screen.

6. 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 when passing the furnace. Any deviation will affect the consistency of the LED brightness that has been set, and color patches with inconsistent brightness will appear.

7. Temperature and time of over-wave soldering

Strictly control the wave front welding temperature and furnace passing time. It is recommended that the preheating temperature be 100 ° C ± 5 ° C, and the maximum temperature should not exceed 120 ° C, and the preheating temperature rise should be stable. It is recommended that the time should not exceed 3 seconds. After passing the furnace, avoid vibration or impact on the LED until it returns to normal temperature. The temperature parameters of the wave soldering machine should be regularly checked, which is determined by the characteristics of the LED. Overheating or fluctuating temperature will directly damage the LED or cause hidden quality problems for the LED, especially for small and round LEDs such as 3mm.

8. Virtual welding control

When full-color LED displays are not lit, there is often more than 50% probability that they are caused by various types of virtual soldering, such as LED pin soldering, IC pin soldering, and pin header mother soldering. The improvement of these problems needs to be strictly improved the process and strengthened quality inspection to solve. The vibration test before leaving the factory is also a good inspection method.