Eight parameters to pay attention to when applying LED beads in the display field

LED beads, as the most expensive and widely used component in LED display screens, play a dominant role in the quality of LED displays. Today we will introduce to you why LED beads are the most critical component of LED display screens, and how to distinguish the advantages and disadvantages of LED beads?

The most critical component of a full-color LED display screen is the LED beads. There are three reasons:

Firstly, LED is the most commonly used key component in a full color screen, with thousands to tens of thousands of LEDs per square meter used;

Secondly, LED is the main determinant of the overall optical display performance, directly affecting the audience's evaluation of the display screen;

Thirdly, LED accounts for the largest proportion of the overall cost of display screens, ranging from 30% to 70%.

How to distinguish the quality of LED display screen beads?

1、 Look at the solder joints. Legitimate LED strip manufacturers produce LED strips using SMT mounting technology, solder paste, and reflow soldering technology

2、 Check the quality of FPC. FPC is divided into two types: deposited copper and rolled copper. The copper foil on the copper plate is protruding, which can be seen from the connection between the solder pad and FPC upon closer inspection

3、 Check the cleanliness of the surface of the LED strip. If the LED strip produced by SMT process is used, its surface cleanliness is very good, and no impurities or stains are visible

4、 The chips and production processes used for LED lights cannot be distinguished with the eyes. Aging equipment and testing equipment should be used. If you put several manufacturers of LEDs on an aging tester and age them with high current for 24 hours or longer, you can measure the brightness of several manufacturers of LEDs and see which one has the smallest attenuation of luminous intensity, and the quality with the smallest attenuation is the best.

What are the effects of LED beads on LED display screens

1. Perspective

The perspective of an LED display screen is determined by the perspective of the LED beads. Currently, most outdoor display screens use a horizontal viewing angle of 100 ° Vertical viewing angle of 50 °; The elliptical LED is used, and the indoor display screen is selected with a horizontal and vertical angle of 120 °; SMT LED. The display screen on highways is generally selected at 30 ° due to its particularity; A circular LED with a viewing angle is sufficient. Some display screens on high-rise buildings require a higher vertical viewing angle. The perspective and brightness are contradictory to each other, and a large perspective will inevitably reduce brightness. The choice of perspective needs to be determined based on the specific purpose.

2. Brightness

LED brightness is an important determinant of display screen brightness. The higher the brightness of the LED, the greater the margin of current usage, which is beneficial for saving power consumption and maintaining LED stability. LEDs have different angle values. When the brightness of the chip is fixed, the smaller the angle, the brighter the LED, but the smaller the viewing angle of the display screen. Generally, 100 degree LED should be selected to ensure sufficient viewing angle of the display screen. A balance should be found between brightness, angle, and price for displays with different point spacing and line of sight.

3. Inefficiency

Due to the fact that a full-color display screen consists of tens of thousands or even hundreds of thousands of pixels composed of red, green, and blue LEDs, the failure of any color LED will affect the overall visual effect of the display screen. Generally speaking, according to industry experience, the failure rate of LED display screens should not exceed 0.03% (referring to the failure caused by the LED beads themselves) before shipment after 72 hours of aging.

4. Antistatic ability

LED is a semiconductor device that is sensitive to static electricity and is prone to electrostatic failure. Therefore, anti-static ability is crucial for the lifespan of display screens. Generally speaking, the failure voltage of LED's human electrostatic mode test should not be lower than 2000V.

5. Lifespan

The theoretical lifespan of LED devices is 100000 hours, which is much longer than the working lifespan of other components of LED display screens. Therefore, as long as the quality of LED devices is guaranteed, the working current is appropriate, the PCB heat dissipation design is reasonable, and the production process of display screens is rigorous, LED devices will be one of the most durable components in the entire display screen.

LED devices account for 70% of the price of LED displays, so LED devices can determine the quality of LED displays. China is not only a major producer of LED devices, but also a gathering place for the production of LED display screens. The high-tech requirements of LED display screens are the future development trend, and the high-quality requirements of LED display screens not only affect the direction of LED display screen manufacturers, but also affect the development of LED display screen device manufacturers. From controlling LED devices, promote China's transformation from a major producer of LED displays to a strong producer of LED displays.

6. Attenuation characteristics

After long-term operation, LED display screens may experience a decrease in brightness and inconsistent display colors, mainly due to the brightness attenuation of LED devices. The attenuation of LED brightness will cause a decrease in the overall brightness of the display screen. The inconsistency in the brightness attenuation amplitude of red, green, and blue LEDs can cause color inconsistency in LED display screens, which is commonly known as the phenomenon of display screen distortion. High quality LED devices can effectively control the amplitude of brightness attenuation. According to the standard of 20mA when lit at room temperature for 1000 hours, the red attenuation should be less than 2%, and the blue and green attenuation should be less than 10%. Therefore, when designing the display screen for blue and green LEDs, it is best not to use 20mA current and only use 70% to 80% of the rated current.

The attenuation characteristics are not only related to the characteristics of red, green, and blue LEDs themselves, but also affected by factors such as current usage, PCB board heat dissipation design, and display screen ambient temperature.

7. Size

The size of LED devices affects the pixel distance, i.e. resolution, of LED display screens. The 5mm elliptical light is mainly used for outdoor display screens above P16, the 3mm elliptical light is mainly used for outdoor display screens at P12.5, P12, and P10, the 3528 type SMT LED is mainly used for indoor display screens at P6 and P8, and the 2020 type SMT LED is mainly used for indoor display screens such as P2 and P3. Under the premise of constant point spacing, increasing the size of LED devices can increase the display area and reduce the graininess. However, due to the reduction of black area, the contrast will be reduced; On the contrary, the decrease in LED size reduces the display area, increases the graininess, increases the black area, and increases contrast.

8. Consistency

A full-color display screen is composed of countless pixels composed of red, green, and blue LEDs. The consistency of brightness and wavelength of each color LED determines the brightness consistency and white balance consistency of the entire display screen.