After several years of development, LED display screens seem to be a mature industry at first glance. In fact, both domestic and foreign manufacturers still have a long way to go, especially for outdoor large screens. After two years of operation, most of the products have It is difficult to maintain within the user’s expectations.　　

Why is this so?

1.First of all, there is a big misunderstanding. Most people think that LED and IC, the main materials of the screen, have a lifespan of 100,000 hours. They operate at 365 days/year and 24 hours/day. The service life is more than 11 years, so most customers Only care about using well-known LEDs and ICs. In fact, these two are only necessary conditions, not sufficient conditions, because the reasonable use of red, green, and blue lamps is more important to the display screen. For lamps of different colors, it is necessary to make them work in the best condition. A good display will be even more important. The reasonable adjustment of IC also helps to overcome the unreasonable wiring problem of PCB. It’s like a car with a good engine and circuit control does not necessarily become a good car. The key factor here is this:

Because LEDs and ICs are semiconductor devices, they are critical to the environmental conditions, preferably at room temperature around 25°C, and their working mechanism is the best. But in fact, a large outdoor screen will be used in different temperature environments, which may be above 60°C in summer and below -20°C in winter. When the manufacturer produces products, the test condition is 25℃, and different products are classified into different grades. The actual operating conditions are 60℃ or -20℃. At this time, the working efficiency and performance of LED and IC are inconsistent, which may originally belong to the first grade. The screen will become multi-speed, the brightness will be inconsistent, and the screen will naturally become blurred.

This is because under different temperature conditions, the brightness attenuation and decline of the red, green, and blue lights are different. At 25°C, the white balance is normal, but at 60°C, the three colors of LEDs The brightness of the screen has been reduced, and the attenuation value is inconsistent, so the brightness of the whole screen will be reduced and the color cast phenomenon will occur, and the quality of the whole screen will be reduced. And IC? The operating temperature range of IC is -40℃—85℃. The temperature inside the box increases due to the high outside temperature. If the temperature inside the box exceeds 85°C, the IC will work unstable due to the high temperature, or the temperature drift will cause the current between channels or the difference between chips to be too large. Causes the screen to flower.

2. LED display power is also very important. Because the power supply has different working stability, output voltage value and load capacity under different temperature conditions, because it is responsible for the logistics support, its support ability directly affects the quality of the screen.

3.The design of the LED cabinet is also very important for the display screen. On the one hand, it has a circuit protection function, and on the other hand, it is a safety function. At the same time, it also has a dust-proof and waterproof function. But the more important thing is whether the design of the thermal circuit system for ventilation and heat dissipation is good. With the extension of the boot time and the increase of the outside temperature, the thermal drift of the components will increase, which will cause the image quality to deteriorate.

These factors are all interrelated, and will affect the quality and life of the display. Therefore, when selecting screens, customers must also observe and analyze them thoroughly and make correct judgments.

The impact of temperature on the large screen is not only that. Assume that the customer has purchased a large screen with a width of 10 meters and a height of 6 meters (60 square meters). Although the total area is not large, the internal composition is each unit box. The temperature is not necessarily balanced, and the temperature in the cabinet is also affected by air convection and the temperature is inconsistent, resulting in different temperatures between the unit cabinets or inside the unit cabinets, resulting in inconsistent working efficiency of semiconductor devices, which manifests as LED lights. The brightness is inconsistent, and it looks like a “flower” screen. Don’t underestimate the outdoor temperature. Just think about the example of boiled eggs in the car in summer. What’s more, the LED display still has to illuminate under the sun exposure in summer. (The emitted light must be stronger than the sun’s light to be effective), its luminescence will inevitably generate heat, these are all influencing factors.

It is not only fragile and delicate semiconductor devices such as LEDs and ICs that fight against hot and cold temperatures, but also solid ABS, masks, iron boxes, connectors, and various soldering points. The masks are exposed to the sun and wet after the rain. Under the multiple impacts of air, some deformations will be caused by up to 2-3mm. In addition, UV radiation will also change the color of the mask plate. In this way, under various climate changes a year, the mask plate itself seen by the audience will change color. Spot plate, deformation will block the luminous angle of the luminous tube and produce dark areas; deformation will also affect the curvature of the PCB board, resulting in weak solder joints, resulting in virtual soldering, which makes the LED light up and off. In addition, due to the moisture and oxidation of the air, the oxidized contact surface of the connector is reduced. With the subtle effects of vibration and deformation, the micron-level plating of the connector does not form a close contact, which causes the signal or power supply to be interrupted, and the large screen fails.

　Deformation and mechanical fatigue will also affect the iron box and the outer frame, resulting in unevenness of the screen, the module and the iron box cannot fit tightly, and some other consequences such as water leakage.

Therefore, to choose a good large screen, you must choose a good lamp in the first line, durable and adaptable, and must not be underestimated in the assessment of other materials and processes. Just like a car, a repair shop of several people can also be pieced together. A car, a factory of tens of thousands of people is also assembling a car, but the number of kilometers and the guarantee factor of the car should be far different. The waterproof and anti-deformation, processing technology of the outdoor screen is the same as that of the key accessories.

In addition to considering the quality of major components such as LEDs and ICs, pre-communication with the seller is also very important. It not only directly affects the quality, success or failure of the entire project, but also often allows users to allocate resources more reasonably, avoid unnecessary waste, loss and hidden dangers, and even increase considerable profits.

Manufacturers should also take the initiative to provide users with simulation solutions or suggestions on actual needs and operability, etc., to help customers analyze and plan rationally, and make the most cost-effective solution in order to become a reliable partner for users. The communication items generally include the following points:

1.be clear about your needs, investment budget and the best expected effect;

2.Indicate the needs of the project and the future development plan in detail, and ask the seller to provide the best implementation plan, even the expandable functions of the project and the expansion of the budget and plan, so as to avoid unnecessary problems caused by the project’s unsuitability for future development needs Waste of resources;

3.Provide or require the manufacturer to analyze data on the installation and application environment of the project, predict and propose preventive and resolution measures for possible incidents, and then make a comprehensive assessment of the entire project plan;

4.Different LED production processes, screen assembly processes, and installation technology experience will directly affect the construction period, cost, safety performance, display effect and quality, service life and maintenance costs of the entire project. Therefore, it must be understood from the manufacturer or multiple aspects beforehand. Compare the performance characteristics of all aspects of products and projects, and choose the most suitable plan for your needs;

5.To understand the strength, integrity, service content and quality of the manufacturer, these are the basis and guarantee for a good and long-term cooperation in the project.

At present, LED full-colour displays generally use (R) red lights for Guanglei and (G, B) green and blue lights for Silan. The high-end die brands unanimously recognized in the industry are CREE, AXT and Japan’s Nichia. Our company can also use the high-end die to produce full-colour LED displays according to customer requirements.
1. CREE: American chip, it has good stability, strong anti-static, etc. It has been unanimously recognized by peers in the use of outdoor display screens. The brightness of pure green tube is up to (1500mcd or more, wavelength: 522-527nm extracted) blue tube brightness (Above 300mcd, wavelength: extracted from 472-477nm)
The maximum to the minimum brightness of the CREE tube is 1:1.2, and the Nichia’s is 1:4, which is six times larger. The brightness difference of other tubes, such as the Taiwan tube, is even more significant, and the brightness balance effect of the CREE tube is due to the brightness. The ratio difference is small and better than other tubes. CREE’s wavelength error rate is plus or minus 0.5nm, while the Nichia wavelength error rate is plus or minus 4nm, which is 1.6 times higher. Other Taiwan tubes’ wavelength error rate exceeds plus or minus 4nm and is more significant than 1.6. Times. CREE adopts single-electrode packaging, which is the best anti-counterfeiting and no counterfeit products. However, Nichia tubes in the domestic market are not strong enough in anti-counterfeiting, and there are often fakes.
2. AXT: The AXT chip of the United States is divided by Dalian Lumei Company. Its brightness is high, and the stability is relatively good. This year, it has been used mostly in outdoor display screens among industry manufacturers. Our company uses a pure green tube with a brightness of more than 2000mcd, extracted from the wavelength of 523-528, and a blue tube with a brightness of more than 350mcd, and the wavelength: extracted from 622-627.
3. Taiwan Opto Lei and Guolian Red Tube are the most widely used in full-colour displays. The red tube’s brightness is above 650mcd, and the wavelength is extracted from 622-627.
4. The central wavelength of the LED display produced by our company is in the range of 5 nanometers, the led display chip size is 13mil or more than 14mil; the waterproof performance of the sealed box is IP65, the gray level is 256, the flatness is good, the white balance reaches 6000CD or more, The frame rate is above 60 Hz per second, and the refresh rate is 480 Hz per second. The above main performances have reached the industry-standard C level