LED display 8 fatal factors you know
Time:2018-10-31
Views:177
LED display, like other things, inevitably encountered in the use of this or that problem and matters needing attention.When using full-color LED big screen, it may cause difficulties or affect the use of big screen because of eight problems, and can extend its service life.
1. Heat dissipation design
The LED will get hot when working, and the high temperature will affect the attenuation speed and stability of the LED. Therefore, the heat dissipation design of PCB plate and the ventilation and heat dissipation design of the box will affect the performance of the LED.
2, mixed light
The LED with the same color and different brightness levels needs to be mixed with the light, or the light is inserted according to the plug-in light diagram designed according to the discrete law to ensure the consistency of the brightness of each color on the screen.If there is a problem in this process, the local brightness of the large screen will be inconsistent, which directly affects the display effect of the LED large screen.
3. Design current value
The nominal current of LED is 20mA. It is generally recommended that the maximum operating current of LED should not exceed 80% of the nominal value, especially for large screens with small point spacing. Due to poor heat dissipation conditions, the current value should also be reduced.According to experience, due to the inconsistency of the attenuation speed of red, green and blue leds, the current value of blue and green leds is reduced to maintain the consistency of white balance after long use of the large screen.
4. Drive circuit design
The layout of the driving circuit board driving IC on the large screen module will also affect the brightness of LED.As the transmission distance of driving IC output current on the PCB board is too far, the voltage drop in the transmission path will be too large, which affects the normal operating voltage of LED and leads to its brightness reduction.We often find that the LED brightness around the large screen module is a little lower than in the middle, which is the reason.Therefore, to ensure the consistency of the screen brightness, drive circuit distribution should be designed.
Control the perpendicularity of the lamp
For the straight through LED, there should be sufficient technology to ensure that the LED is perpendicular to the PCB.Any deviation will affect the brightness consistency of the already set LED, and there will be color blocks with different brightness.
6. Virtual welding control
When the LED does not light up, there is always more than 50% probability that the LED will be caused by various types of virtual welding, such as LED pin virtual welding, IC pin virtual welding, and pin virtual welding.The improvement of these problems requires strict improvement of process and quality inspection.The vibration test before delivery is also a good test method.
7. Temperature and time of wave crest welding
Must strictly control the wave crest welding temperature and furnace time, recommended for: preheat temperature 100 ℃ + / - 5 ℃, the highest do not exceed 120 ℃, and the requirement of preheating temperature increasing is smooth, the welding temperature is 245 ℃ + 5 ℃, welding time suggest no more than 3 seconds, after furnace vibration or shock LED of avoid by all means, until the normal temperature state.Temperature parameters of wave soldering machine should be tested regularly, which is determined by the characteristics of LED. Overheating or fluctuating temperature will directly damage the LED or cause the LED quality hazard, especially for small size like 3mm round and oval LED.
8. Anti-static
There should be good anti - static measures in the large - screen LED assembly plant.Special anti-static ground, anti-static floor, anti-static soldering iron, anti-static radio pad, anti-static ring, anti-static clothing, humidity control, equipment grounding (especially the cutting machine) are the basic requirements, and should be tested regularly with static electricity.
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