LED lamp beads on the LED screen influence of quality
LED lamp beads are the bargaining chip for many businesses to survive, and the product quality is uneven. The LED lamp bead is the most important part of the LED display. Among many accessories, it is the most important part. The quality of the LED lamp bead directly affects the quality of the LED display.
1. Perspective
The viewing angle of the LED display depends on the viewing angle of the LED lamp beads. At present, most LED displays use elliptical LEDs with a horizontal viewing angle of 100° and a vertical viewing angle of 50°. Due to its particularity, the display screen on the highway generally uses a circular LED with a viewing angle of 30°. Displays on some tall buildings require higher 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 an important determinant of display brightness. The higher the brightness of the LED, the greater the margin of the current used, which is good for saving power consumption and keeping the LED stable. 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. 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 is composed of tens of thousands or even hundreds of thousands of pixels composed of three types of red, green, and blue LEDs, the failure of any color LED will affect the overall visual effect of the display. Generally speaking, according to industry experience, the failure rate of LED display should not be higher than 3/10,000 (referring to the failure caused by the LED lamp bead itself) before the LED display starts to be assembled and aged for 72 hours before shipment.
4. Antistatic ability
LED is a semiconductor device, which is sensitive to static electricity and can easily lead to static electricity failure. Therefore, the anti-static 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 the LED device 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 device is guaranteed, the working current is suitable, the PCB heat dissipation design is reasonable, and the production process of the display is rigorous, the LED device will be the entire display. One of the most durable parts in a machine.
LED devices can determine the quality of the LED display. my country is not only a big producer of LED devices, but also a gathering place for LED display production. The high-tech requirements of LED display are the future development trend. The high-quality requirements of LED display are not only about the trend of LED display manufacturers, but also the development of LED display device manufacturers.
6. Attenuation characteristics
After the LED display works for a long time, there will be a phenomenon that the brightness decreases and the color of the display is inconsistent, which is mainly caused by the brightness attenuation of the LED device. The attenuation of LED brightness will reduce the brightness of the entire display screen. The inconsistency of the brightness attenuation of the red, green and blue LEDs will cause the inconsistency of the color of the LED display, which is the phenomenon that we often say that the display is spent. High-quality LED devices can well control the magnitude of brightness attenuation. According to the standard of 20mA lighting for 1000 hours at room temperature, the red attenuation should be less than 2%, and the blue and green attenuation should be less than 10%. Therefore, the blue and green LEDs should not use 20mA current when designing the display screen, and it is best to use only 70% to 80%. % of rated current.
In addition to the attenuation characteristics related to the characteristics of the red, green and blue LEDs themselves, 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. 5mm elliptical lights are mainly used for outdoor displays above P16, 3mm elliptical lights are mainly used for P12.5, P12, P10 outdoor displays, 2020 type SMD LEDs are mainly used for P2, P3 and other indoor displays. Under the premise that the dot pitch remains unchanged, the size of the LED device increases, which can increase the display area and reduce the graininess. However, due to the reduction of the black area, the contrast ratio will be reduced; on the contrary, the size of the LED will decrease, reducing the display area and increasing the graininess. , the black area increases, increasing the contrast.
8. Consistency
The LED display screen is composed of pixels composed of numerous red, green and blue LEDs. The consistency of the brightness and wavelength of each color LED determines the brightness consistency, white balance consistency and chromaticity consistency of the entire display screen. . 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 the device supplier through a spectroscopic color separation machine. The consistency of voltage is generally not required.
The angle consistency of red, green, and blue LEDs will seriously affect the consistency of white balance at different angles, and directly affect the fidelity of video color on the display. 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 design of the packaging lens and the selection of raw materials, which depends on the technical level of the packaging supplier. No matter how good the normal direction white balance is, if the LED angle consistency is not good, the white balance effect of different angles of the whole screen 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.
