Detailed explanation of key components of LED display LED lamp beads

The most important part of a full-color display is the lamp bead. There are three reasons: first, LEDs are the key components used in the largest number of full-color screens, and thousands to tens of thousands of LEDs are used per square meter; second, LEDs are the main body that determines the optical display performance of the entire screen, directly affecting the audience. Evaluation of the display screen; Third, LEDs account for the largest proportion of the overall cost of the display screen, ranging from 30% to 70%. How to identify the advantages and disadvantages of LED display lamp beads 1: Look at the solder joints.

The LED light strips produced by regular LED light strip manufacturers are produced by SMT chip technology, solder paste and reflow soldering process. Two: Look at the quality of FPC. FPC is divided into two types: copper clad and rolled copper. The copper foil of the copper clad plate is protruding. If you look closely, you can see it from the connection between the pad and the FPC.

Three: Look at the cleanliness of the surface of the LED strip. If the LED light strip produced by SMT process is used, the surface cleanliness is very good, and no impurities and stains can be seen. Four: Look at the chip and production process used in LED lights. You can’t tell the difference with your eyes. You need to use aging equipment and testing equipment. Time, you go to measure the LED brightness of several manufacturers to see which LED has the smallest attenuation of luminous intensity, and the quality with the smallest attenuation is the best.

What are the effects of LED lamp beads on the LED display? At present, most of the outdoor display screens use elliptical LEDs with a horizontal viewing angle of 100°; and a vertical viewing angle of 50°; indoor displays use SMD LEDs with a horizontal and vertical viewing angle of 120°; Due to its particularity, the display screen on the highway generally chooses 30°; a circular LED with a viewing angle is enough.

Display screens on some high-rise buildings have higher requirements for vertical viewing angles. The viewing angle and brightness are contradictory, and a large viewing angle will inevitably reduce the brightness. The choice of viewing angle needs to be determined according to the specific use.

2. Brightness LED brightness is the determining factor of display brightness. The higher the brightness of the LED, the larger the margin of the current used, which is good for saving power consumption and maintaining the stability of the LED. 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.

Generally, a 100-degree LED should be selected to ensure a sufficient viewing angle for the display. For displays with different dot pitches and different viewing distances, a balance point should be found in brightness, angle and price. 3. Failure rate Since the full-color display screen is composed of tens of thousands or even hundreds of thousands of red, green and blue LED pixels, 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 the LED display screen should not be higher than 3/10,000 (referring to the failure caused by the LED lamp bead itself) from the beginning of assembly to the aging of 72 hours before shipment. 4. Antistatic ability LED is a semiconductor device, which is sensitive to static electricity and can easily cause electrostatic failure. Therefore, antistatic ability is very important to the life of the display screen. Generally speaking, the failure voltage of LED human body electrostatic mode test should not be lower than 2000V.

5. Lifespan The theoretical life of LED devices is 100,000 hours, which is much longer than the working life of other components of the LED display. Therefore, as long as the quality of the LED devices is guaranteed, the working current is appropriate, the heat dissipation design of the PCB is reasonable, and the production process of the display is rigorous, the LED device is a display One of the most durable parts in the screen machine. LED devices account for 70% of the price of LED displays, so LED devices can determine the quality of LED displays. my country is not only a big producer of LED devices, but also a gathering place for LED display manufacturing.

The high-tech requirements of LED displays are the future development trend. The high-quality requirements of LED displays are not only about the direction of LED display manufacturers, but also implicated in the development of LED display device manufacturers. From the gate of LED devices, promote China's transformation from a big LED display manufacturing country to a powerful LED display manufacturing country. 6. Attenuation characteristics After working for a long time, the brightness of the LED display will decrease and the color of the display will be inconsistent, mainly due to the attenuation of the brightness of the LED device.

The attenuation of LED brightness will reduce the brightness of the entire screen of the display screen. The inconsistency of red, green, and blue LED brightness attenuation will cause inconsistency in the color of the LED display, which is what we often call the phenomenon of the display screen being spent. High-quality LED devices can well control the brightness attenuation.

According to the standard of 20mA at room temperature for 1000 hours, the attenuation of red should be less than 2%, and the attenuation of blue and green should be less than 10%. Therefore, blue and green LEDs should not use 20mA current when designing the display screen. % of rated current. The attenuation characteristics are not only related to the characteristics of the red, green, and blue LEDs themselves, but also the current used, the heat dissipation design of the PCB board, and the ambient temperature of the display screen all affect the attenuation. 7. Size The size of the LED device affects the pixel distance of the LED display, that is, the resolution.

The 5mm oval light is mainly used for outdoor displays above P16, the 3mm oval light is mainly used for P12.5, P12, P10 outdoor displays, and the 3528 SMD LED is mainly used for P6, P8 indoor displays. 5050 SMD LEDs are mainly used for P16, P12.5 and other semi-outdoor display screens. Under the premise of keeping the dot pitch constant, increasing the size of the LED device can increase the display area and reduce the graininess, but the contrast will be reduced due to the reduction of the black area area; on the contrary, the reduction in the size of the LED will reduce the display area and increase the graininess , the area of ​​the black area increases, increasing the contrast. 8. Consistency The full-color display screen is composed of countless red, green, and blue LED pixels. The brightness and wavelength consistency of each color LED determine the brightness consistency and white balance consistency of the entire display screen. , Chromaticity consistency.

Generally speaking, display manufacturers require device suppliers to provide LEDs with a wavelength range of 5nm and a brightness range of 1:1.3. These indicators can be achieved by device suppliers through grading by spectroscopic and color separation machines. Voltage consistency is generally not required. Since the LED is angled, the full-color LED display also has angle directionality, that is, its brightness will increase or decrease when viewed from different angles.

In this way, the angular consistency of the red, green, and blue LEDs will seriously affect the consistency of the white balance at different angles, and directly affect the fidelity of the video color of the display screen. To achieve the matching consistency of the brightness changes of the red, green, and blue LEDs at different angles, it is necessary to strictly carry out scientific design in the packaging lens design and raw material selection, which depends on the technical level of the packaging supplier. No matter how good the white balance is in the normal direction of the display, if the angle consistency of the LEDs is not good, the white balance effect of the whole screen at different angles will be bad.

The angle consistency characteristics of LED lamp beads can be measured by LED angle comprehensive tester, which is especially important for medium and high-end display screens. .