Factors affecting the use of LED display
LED display and other items, in the use of unavoidable encounter problems of one kind or another. In the use of LED display, may be due to heat dissipation design, mixed lamp eight problems, resulting in difficulties or affect the use of LED display. In order to make the later use of LED display efficiency stability, the first thing to do is to prevent its aging. The following is a detailed explanation of the factors affecting the use of LED display and do a good job of preventing LED display aging points. Do you know the drive and control method of LED display?
There are 8 factors affecting the use of LED display
1. Heat dissipation design
Beijing LED display manufacturers said LED work will heat, the temperature is too high will affect LED decay speed and stability, so PCB board cooling design, ventilation and cooling design of the box will affect the performance of LED.
2. Mixed lights
Leds of the same color with different brightness levels need to be mixed or inserted in accordance with the discrete law of the design of the plug-in diagram, so as to ensure the consistency of the brightness of each color in the whole screen. If there is a problem in this process, there will be inconsistency in the local brightness of the large screen, which directly affects the display effect of the led screen.
3, design the current value
LED nominal current is 20mA, it is generally recommended that the maximum use current is not more than 80% of the nominal value, especially for the point spacing is very small large screen, due to poor heat dissipation conditions, should also reduce the current value. As a rule of thumb, due to the inconsistency of decay rate of red, green and blue LED, the current value of blue and green LED is reduced in order to maintain the consistency of white balance after long use of large screen.
4. Drive circuit design
The driver IC layout of the driver circuit board on the large screen module will also affect the brightness of the LED. Because the transmission distance of the output current of the driving IC on the PCB board is too far, the voltage drop of the transmission path will be too large, which will affect the normal working voltage of the LED and lead to the reduction of its brightness. This is why we often find that the leds around large screen modules are less bright than in the middle. Therefore, to ensure the consistency of large screen brightness, it is necessary to design a good driver circuit distribution diagram.
5. Control the verticality of the lamp
For the in-line LED, there should be enough process technology to ensure that the LED is perpendicular to the PCB board during the furnace. Any deviation will affect the LED brightness consistency that has been set, resulting in inconsistent color blocks.
6. Virtual welding control
led large screen screen in the LED is not bright, often more than 50% probability for various types of virtual welding caused, such as LED pin welding, IC pin welding, pin row female virtual welding. To solve these problems, we need to improve the process strictly and strengthen the quality inspection. The vibration test before leaving the factory is also a good inspection method.
7. Temperature and time of over-wave soldering
LED display manufacturers say that it is necessary to strictly control the temperature of wave front welding and the furnace time, the recommendation is: preheating temperature 100℃±5℃, the maximum is not more than 120℃, and the preheating temperature rise is required to be stable, the welding temperature is 245℃±5℃, the welding time is not more than 3 seconds, after the furnace do not vibration or impact LED, until the normal temperature is restored. The temperature parameters of wave welding machine should be tested regularly, which is determined by the characteristics of LED. Overheating or fluctuating temperature will directly damage LED or cause hidden dangers of LED quality, especially for small size such as 3mm round and oval LED.
8, anti-static
led screen assembly factory should have good anti-static measures. Special anti-static ground, anti-static floor, anti-static soldering iron, anti-static station mat, anti-static ring, anti-static clothes, humidity control, equipment grounding (especially the foot cutting machine) are the basic requirements, and should be tested regularly with electrostatic instrument.
Do a good job of LED screen aging points
Aging is an important guarantee of the reliability of electronic products, and is the last indispensable step of product production. LEDj display products can improve performance after aging and help stabilize performance in later use. LED display aging test is a very important link in product quality control, but it is often ignored in many times, unable to carry out correct and effective aging.
LED display aging test is a countermeasure taken according to the characteristics of the product’s failure rate curve, namely bath curve, to improve the reliability of the product. However, this method is not necessary, after all, aging test is at the cost of sacrificing the life of a single LED display product.
LED display aging modes include constant current aging and constant voltage aging. A constant current source is one in which the current is constant at all times. If you have frequency, it’s not constant current. That’s alternating current or pulsating current. Ac or pulsating current sources can be designed to be constant RMS, but such sources cannot be called “constant current sources”.
LED display manufacturers say constant current aging is the most consistent with LED display current working characteristics, is the most scientific LED display aging way; Overcurrent impact aging is also one of the latest aging methods used by manufacturers, through the use of frequency adjustable, current adjustable constant current source for such aging, in order to judge the quality life expectancy of LED display in a short time, and can pick out a lot of conventional aging can not pick out the hidden dangers of LED display.
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