In recent years, the application of small-pitch led display has become more and more popular. With the unique advantages of display effects, its application places range from down to ordinary conference rooms, monitoring rooms, exhibition display applications, to national conference centers, monitoring centers, and CCTV. And large events. For example, last year's G20 meeting, Tianjin National Games, the small-pitch led display is everywhere.

       As a new technology and high-precision equipment, the user needs to remove the excellent display effect, but also with stability considerations, because once the black screen of the main venue, it will have a major international impact, even political influence, such as the Tianjin National Games. The 5 ring changes to 4 rings. Therefore, when the small-pitch LED is used as the main screen of the venue, its stability assessment is among the most important. The first one is that it cannot be black.

Analysis of the black screen of never black screen

       Because of this demand, we thoroughly analyze the reasons for the black screen, in order to fundamentally eliminate the hidden danger of the black screen, and truly never black screen. The display is an electronic device, the internal control card chip is an FPGA, and there is no operating system, so the cause of the black screen can be classified into two major parts, one is a device failure, and the other is a cable failure.

      1. Equipment failure / receiving card

      There are many devices on the receiving card. One ordinary receiving card is composed of two Gigabit network communication interfaces, 120P light board driving interface, SDRAM, FLASH, etc. The soldering point is more than 10,000 points, because the LED is an inductive load, resulting in its The working environment is more complicated. Some manufacturers sacrifice internal heat dissipation space in pursuit of ultra-thin, use mini card, etc., their electronic devices have many contacts, the electromagnetic environment is complex, and the internal high thermal environment leads to a decrease in working stability. A sporadic capacitor failure may cause a screen. The display is not normal.

Receiving card front and back pictures

      1. Equipment failure / power switch failure

       The led display is an inductive load, and the output load varies with the screen, which has a large impact on internal devices, and the internal capacitance of the switching power supply is large, and some manufacturers use a switching power supply with automatic fan cooling in order to reduce the use cost. Since both capacitors and fans have a short lifetime, they are the most common cause of switching power supply failures, and black screen failures caused by power failures in the entire device are at the top of the list.

       2. Cable failure / external cable

       Cable faults are mainly divided into external connection cables, such as cables that provide power and signals to the screen, and internal cable faults, such as internal DC power lines, internal gray lines, and so on.

       Among the external cables, the signal cable has the highest failure rate and the greatest impact. The signal cable used in the display screen is cat5e cable. It is difficult to ensure the stability of signal communication due to material construction and other factors, especially the 2-end crystal head docking, and the vibration resistance is relatively poor.

       The internal cables are mainly gray cables, as shown below. Most of the gray wire is made by cold pressing. After repeated insertion and removal, the contacts are easily contacted badly, and even the gray wire is broken. Therefore, the internal cable failure is the highest among all cable connection failures.

Never black screen response strategy

       The above analysis of several reasons for the black screen, we will prescribe the right medicine, from the design side to shield the above problems, fulfill the commitment to customers and users - never black screen.

     Never one of the black screen weapon: no receiving card

       Compared with the traditional receiving card design, our company designs a non-receiving card solution and integrates the products highly.

As shown in the figure above, a more integrated dedicated chip is designed on the transfer board. The chip integrates Gigabit network communication, FPGA, SRAM, FLASH, MCU, etc. in the conventional receiving card. The original 7 ICs are now changed to 1 IC, which is highly integrated and reduces solder joint connection by 80%. Reduce the failure rate of electronic devices, thereby improving system stability.

    Never black screen weapon 2: no cable, connector hard connection

       Compared with the previous cable connection, there is no connection cable inside, and all transmissions are carried out through the PCB and the connector. From the design end, the multiple insertion and removal fatigue of the cable and the contact failure caused by the conventional cold pressure are avoided. Hidden dangers.

    Never black screen weapon three: dual power supply

       As mentioned above, in the case of device failure, the switching power supply failure is the first, so dual-power backup is generally used for high-end applications. Therefore, the designed switching power supply has an automatic current sharing function, that is, two power supplies are simultaneously output at half time, which can reduce the working load of the power supply, prolong the service life of the power supply, and avoid the impact of the power grid caused by the cold switching of the power supply, and the display is brought about. The jitter or third harmonic causes the device to restart, and the power status can be monitored in real time on the software side, and can be quickly replaced during maintenance to eliminate the fault.

Never black screen weapon four: loop design

        Four levels of backup can be done according to the level of the site's signal stability requirements and cost budget. The most important of these two levels of backup, one is dual interface, dual circuit, one is dual interface four circuit. The dual interface dual loop is generally used for TV stations, while the dual interface four loops are used for live broadcast, national level on-site conferences, etc.

     Dual interface dual circuit with never black screen loop design

As shown in the figure above, the dual signals form two independent signal loops, which ensures that when one loop fails, the other loop can be switched immediately, and the switching time is <0.1ms. For some TV stations that require power interface hot standby, you can increase the power connector to achieve dual power supply, dual signal on the screen, and output 2 independent copy signals to the 2 send boxes through the backup board at the splicer end.

Never interface black screen loop design dual interface four circuit

As shown in the signal wiring diagram above, this backup level is the most advanced, that is, the four input ports of the signal, as long as one is normal, it can work normally. The main screen of the Guangzhou Asian Games venue adopts this backup mode. Of course, this backup method will increase the cost of the front-end equipment, which is usually more than 4 times higher than the conventional configuration.

        Conclusion

        There is no best, only better, and the road to technology is never ending. Bright color adheres to the characteristics of professional, special research and perseverance, and constantly works on led display products; through in-depth contact with customers, we continuously develop small-pitch products that meet market demand. And through the advantages of technology precipitation, the LED display is gradually extended to a wider application market, with technical strength to eliminate customer worries and create maximum value for customers.

Source: LED big screen network