In recent years, the application of small pixel pitch LED displays has become increasingly popular. With the unique advantages of display effects, their applications range from ordinary meeting rooms, monitoring rooms, exhibition and display applications, to national conference centers, monitoring centers, CCTV, and large-scale events.
However, as a new technology and high-precision device, user demand is accompanied by stability considerations in addition to excellent display performance.
Therefore, when small pixel pitch LED is used as the main screen of the venue, its stability assessment is of paramount importance, and the first and foremost thing is that the screen should not be black.
1. The Reasons That Cause the Screen Black
Due to this demand, we can thoroughly analyze the causes of black screen to fundamentally eliminate the hidden dangers of black screen and truly achieve never black screen. The display screen is an electronic device, and the internal control card chip is FPGA.
There is no operating system. Therefore, the causes of black screen can be classified into two major categories, one is device failure, and the other is cable failure.
(1) Device Failure
Equipment failures mainly occur in two devices, the receiving card and the power supply.
A: Receiving Card
There are many devices on the receiving card. An ordinary receiving card combines two-gigabit network communication interfaces, a 120P light board driver interface, SDRAM, FLASH, etc. With over 10000 solder joints, the LED is a perceptual load, resulting in a relatively complex working environment.
Some manufacturers sacrifice internal heat dissipation space in pursuit of ultra-thin, using mini cards and other devices.
Their electronic devices have many contacts, a complex electromagnetic environment, and a high internal thermal environment, resulting in reduced working stability. An occasional capacitor failure may cause abnormal screen display.
B: Power Supply
LED display screens are inductive loads, and the output load varies with the screen, which has a significant impact on internal devices. In addition, there is a large amount of internal capacitance in switching power supplies.
However, some manufacturers use switching power supplies with automatic fan cooling in order to reduce operating costs.
Due to the short service life of both capacitors and fans, they have become one of the most common causes of switching power supply failures, and the black screen failures caused by power failures rank first among the entire device equipment.
Cable failures are mainly divided into external connecting cables, such as those that provide power and signal to the screen, and internal cable failures, such as internal DC power cables, internal gray flat cables, etc.
A: External Cables
The signal cable has the highest failure rate and the greatest impact among external cables.
The conventional signal cable used for display screens is a cat5e cable, which is difficult to ensure the stability of signal communication due to factors such as material construction.
Especially, the 2-end crystal head butt joint has poor vibration resistance.
B: Internal Cable
The internal cables are mainly gray flat cables, as shown in the following picture. The gray wire is mostly made by cold pressing, and after multiple plugging and unplugging, the contact is extremely prone to poor contact, and even the gray wire breaks.
Therefore, internal cable failures are the highest occurrence rate of all cable connection failures.
2. Strategies to Solve The Screen Black
(1): No Receiving Card
Compared to the traditional receiver card design, our company adopts a receiver card-free scheme to highly integrate the product,
As shown in the above figure, a dedicated chip with higher integration is designed on the adapter board.The chip internally integrates gigabit network communication, FPGA, SRAM, FLASH, MCU, etc. in conventional receiving cards.
The original 7 ICs have now been changed to 1 IC, with a high degree of integration, reducing solder joint connections by 80%, reducing the failure rate of electronic devices from the front end, thereby improving system stability.
(2)：No Data Cable
Compared to the flat cable connection, there is no connecting cable inside. And all transmission is conducted through PCBs and connectors, avoiding hidden dangers such as multiple plugs and pull fatigue of the cable, and poor contact caused by conventional cold pressing from the design side.
(3): Dual Power Backup
Among device failures, switching power supply failures are the first, so dual power backup is commonly used in high-end applications. At the same time, the switching power supply designed by our company has an automatic current sharing function.
Two power supplies are output at half capacity at the same time, which can reduce the workload of the power supply, extend the service life of the power supply, and avoid the power grid impact caused by cold switching of the power supply, resulting in display jitters or third harmonic waves that cause equipment restart.
At the same time, the software terminal can monitor the status of the power supply in real-time, and can also be quickly replaced during maintenance to eliminate faults.
UNIT Full-Function Rental LED Display
(4): Loop Design
According to the level and cost budget of on-site signal stability requirements, our products can complete four levels of backup. The two most important levels of backup are dual interface, dual loop, and dual interface, four loop.
Dual interface and dual circuit are generally used in television stations, while the dual interface and four circuits are used for live broadcasting, national level on-site meetings, etc.
As shown in the picture above, two independent signal loops are formed by dual signals, which can ensure that if one set of loops fails, the other set of loops can be immediately switched over, with a switching time of<0.1 ms.
For some TV stations that require power interface hot standby locations, power connectors can be added to achieve a dual power supply and dual signal display.
At the splicer end, two independent duplicate signals can be output to two transmission boxes through a backup board card.