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2, the design of the current value of the LED nominal current of 20mA, generally recommended that the maximum use of current is not more than 80% of the nominal value, especially for small dot spacing display, due to poor heat dissipation conditions, but also should reduce the current value . According to experience, due to the inconsistencies in the attenuation speeds of the red, green, and blue LEDs, the current values ​​of the blue and green LEDs are purposely reduced to maintain the consistency of the white balance after the display has been used for a long time.
3, heat dissipation design LED will work when the heat, the temperature will affect the LED decay speed and stability, so the PCB board cooling design, ventilation and heat dissipation design of the box will affect the performance of the LED.
4. Driver circuit design The arrangement of the driver circuit board driver IC on the display module also affects the brightness of the LED. Because the output current of the driver IC is too far from the PCB, the voltage drop of the transmission path will be too large, which will affect the LED's normal operating voltage and cause its brightness to decrease. We often find that the brightness of the LED around the display module is lower than in the middle, which is the reason. Therefore, to ensure the consistency of the display brightness, it is necessary to design the drive circuit distribution map.
5, mixed lights of the same color with a different brightness of the LED lights need to mix, or in accordance with the discrete rules of the plug-in lamp design to insert the lights, in order to ensure the consistency of the brightness of the entire screen for each color. If there is a problem in this process, there will be inconsistencies in the local brightness of the display screen, directly affecting the display effect of the LED display.
6. Control the verticality of the lamp For the in-line LED, there must be enough technology to ensure that the LED is perpendicular to the PCB board. Any deviation will affect the brightness consistency of the LED that has been set, and the color patches with inconsistent brightness appear.
7, over wave soldering temperature and time must be strictly controlled wave front welding temperature and furnace time, it is recommended as follows: preheat temperature 100 °C ± 5 °C, the maximum does not exceed 120 °C, and the preheating temperature rise requires a smooth, welding temperature For 245 °C ± 5 °C, welding time is recommended not to exceed 3 seconds, after the furnace avoid vibration or shock LED, until the return to normal temperature. Wave soldering machine temperature parameters should be regularly tested, which is determined by the characteristics of the LED, overheating or fluctuating temperature will directly damage the LED or cause LED quality problems, especially for small size such as 3mm round and oval LED.
8ã€Cold-welded control LED display When the LED is off, there are often more than 50% of the probability of various types of false welds, such as LED pin virtual welding, IC pin virtual welding, row pin mother mother welding Wait. Improvements in these issues need to be strictly improved and enhanced quality inspections to solve. The factory vibration test is also a good test method.
Points for attention in designing full-color LED display screens
LED display screen and other items, in use will inevitably encounter such or that problems and precautions 1, anti-static LED display assembly plant should have good anti-static measures. Special 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) are all basic requirements, and should be regularly tested with a static instrument. .