For a full-color LED display, LED lamp beads are the most critical component, and the quality of the LED lamp beads plays an important role in determining the quality of the LED display. First of all, the number of LED lamp beads used in the entire full-color LED display is very large. There may be thousands or even tens of thousands of LED lamp beads per square meter. Secondly, the parameters of the LED lamp beads directly determine the display of the full-color LED display. The performance, color saturation, and clarity of the camera.
The important indicators of the quality of LED lamp beads are as follows:
1. The viewing angle of the LED display
The viewing angle of the LED display is determined by the viewing angle of the LED lamp beads. At present, most outdoor displays 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°. Because of its particularity, a circular LED with a viewing angle of 30° is generally sufficient for the display on the highway. Some high-rise display screens have higher requirements for vertical viewing angles. The viewing angle and brightness are contradictory. Large viewing angles will inevitably reduce the brightness, so the choice of viewing angle needs to be determined according to the specific purpose.
2. The size of the LED display
The size of the LED device affects the pixel point distance of the LED display screen, that is, the resolution. 5mm oval lights are mainly used for outdoor displays above P16, 3mm oval lights are mainly used for outdoor displays of P12.5, P12, P10, and 3528 SMD LEDs are mainly used for indoor displays of P6 and P8. 2020-type SMD LEDs are mainly used for indoor displays such as P2 and P3. Under the premise that the dot pitch is constant, the size of the LED device can increase, which can increase the display area and reduce the graininess, but because the black area is reduced, the contrast will be reduced. On the contrary, the LED size is reduced, the display area is reduced, and the graininess is increased. , The area of the black area increases, increasing the contrast.
3. Brightness of full-color LED display
The brightness of the LED lamp beads determines the brightness of the full-color LED display. The higher the brightness of the LED lamp beads, the greater the margin of the use current, which is good for saving power consumption and keeping the LED lamp beads stable. LED lamp beads 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, LED lamp beads of 100 degrees -110 degrees should be selected to ensure that the full-color LED display has sufficient viewing angle.
4. The failure rate of full-color LED display
The LED display is composed of tens of thousands or even hundreds of thousands of groups of red, green and blue LED lamp beads. The failure rate of the lamp beads will not exceed one ten thousandth even if they are aged for 72 hours.
5. Attenuation characteristics of full-color LED display
The brightness of the LED lamp beads will slowly decay as the use time increases. The decay speed of the brightness of the LED lamp bead is related to the LED chip, auxiliary materials, and packaging technology to a certain extent. Generally speaking, after 1000 hours, 20 mA normal temperature lighting test, the attenuation of red LED lamp beads should be less than 7%, and the attenuation of blue and green LED lamp beads should be less than 10%. The consistency of red, green and blue attenuation is correct The white balance of the full-color LED display will have a great impact in the future, which will affect the display fidelity of the display.
6. The antistatic ability of the LED display
As LED lamp beads are semiconductor devices, they are sensitive to static electricity and can easily cause static failure, so the antistatic ability is very important to the life of the LED display. Generally speaking, the failure voltage of the human body electrostatic mode test of LED lamp beads should not be lower than 2000V.
7. The life of the LED display
The theoretical life of the LED device is 100,000 hours, which is much longer than the working life of other parts 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 display screen production process is rigorous, the LED device will be the entire display screen. One of the most durable parts in the machine.
8. The consistency of the LED display
The full-color display is composed of countless red, green, and blue LEDs. The brightness and wavelength consistency of each color LED determines the brightness consistency, white balance consistency and chromaticity of the entire display. Sex. Generally speaking, display screen 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 spectroscopy machine. The consistency of voltage is generally not required.
Since the LED is angled, the full-color LED display also has angular directionality, that is, when viewed from different angles, its brightness will increase or decrease. In this way, the angle 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 package lens design and raw material selection, which depends on the technical level of the package supplier. No matter how good the directional white balance is, if the LED angle consistency 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 with a comprehensive LED angle tester, which is particularly important for medium and high-end displays.
