Talk about the influence of LED lamp beads on LED display?
LED lamp beads are a very important part of LED display screens, so what impact will different lamp beads have on the display screen? The impact of LED lamp beads on the LED display is mainly manifested in the following aspects:
1. Perspective
The viewing angle of the LED display depends on the viewing angle of the LED lamp beads. 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°; while 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 an important determinant 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 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. 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 lead to static failure. Therefore, the 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 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 appropriate, the PCB heat dissipation design is reasonable, and the production process of the display is rigorous, the LED device will be the entire display screen. One of the most durable parts in the 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 the LED display screen works for a long time, the brightness will decrease and the color of the display screen will be 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 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. 2020 SMD LEDs are mainly used for indoor display screens such as P2 and P3. On 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 will be reduced; on the contrary, the LED size is reduced, the display area is reduced, and the graininess increases. , 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, white balance consistency, and chromaticity consistency of the entire display screen. sex. 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 poor. 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.
