LED display screen is widely used, such as in led wall advertising, which has the characteristics of clear picture, long life, low energy consumption and so on. If the display screen on the LED advertising wall is not properly designed, it will affect the future use. This paper summarizes five factors that affect the LED display screen:
When led wall advertising equipment works, it will generate heat. Too high temperature will affect the attenuation speed and stability of LED. Therefore, the design of heat dissipation of PCB board and the design of ventilation and heat dissipation of box will affect the performance of LED.
The LEDs with the same color and different brightness levels need to be mixed or inserted according to the lamp inserting diagram designed according to the discrete law to ensure the consistency of the brightness of each color on the whole 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.
The nominal current of LED is 20mA. Generally, it is recommended that the maximum current should not exceed 80% of the nominal value. Especially for the large screen with small point spacing, due to the 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 purposely reduced to maintain the consistency of white balance after the large screen is used for a long time.
The layout of the driving circuit board driving IC on the large screen module of the led wall advertising will also affect the brightness of the LED. Because the driving IC output current is too far away from the PCB, the transmission path voltage drop 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, to ensure the consistency of the brightness of the large screen, it is necessary to design the distribution diagram of the driving circuit.
The temperature and time of wave front welding must be strictly controlled. It is suggested that the preheating temperature should be 100 ℃± 5 ℃, and the maximum temperature should not exceed 120 ℃, and the preheating temperature should rise steadily. The welding temperature should be 245 ℃± 5 ℃, and the welding time should not exceed 3 seconds. After passing through the furnace, it is forbidden to vibrate or impact the LED until the normal temperature is restored. The temperature parameters of the wave soldering machine should be tested regularly, which is determined by the characteristics of the LED. The overheated or fluctuating temperature will directly damage the LED or cause the potential quality hazard of the LED, especially for the small size such as 3mm Round and Oval LED.