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The 8 indicators of LED index determine the quality of your display

Led lamp is the bargaining chip for many businesses, LED lamp market mixed, product quality uneven. LED lamp beads is the most important part of the LED display. Among the many accessories, it is the most important part. The quality of the LED lamp beads directly affects the quality of the LED display.


1.Angle of view

The viewing angle of the LED display is determined by the viewing angle of the LED lamp. At present, most of the LED display screens use elliptical LEDs with  horizontal viewing angle of 100° and vertical viewing angle of 50°. For the indoor display screens use the SMD LED with horizontal and vertical viewing angle of 170°. The display screen on the freeway generally uses a round LED with viewing angle of 30° for its particularity. Some high-rise displays require a higher vertical viewing angle. The viewing angle and brightness are mutually contradictory, and large viewing angle will inevitably reduce the brightness. The choice of viewing angle needs to be decided according to the specific purpose.


           


2.Brightness

LED brightness is an important determinant of display brightness. The higher the brightness of the LED, the greater the remaining amount of current used, which is good for saving power and keeping the LED stable. The LED has different angle values. In the case that the chip brightness is fixed, the smaller the angle is, the brighter of LED is, but the smaller the viewing angle of the display screen is. For display screens with different pixel pitch and different viewing distance, a balance should be found in brightness, angle, and price.



3.Inefficiency

Since full-color display consists of tens or hundreds of thousands of pixels consisting of red, green and blue LEDs, the failure of any color LED will affect the overall visual effect of the display. In general, according to industry experience, the failure rate of LED display from starts to assemble to aging for 72 hours before shipment should not exceed  3/10000 (refer to the failure caused by the LED lamp itself).



4.Anti-static ability

LED is a semiconductor device, which is sensitive to static electricity and can easily cause static electricity failure. Therefore, anti-static ability is very important for the life of the display. In general, the human body electrostatic model test LED failure voltage should not be less than 2000V.


5.Lifespan

The theoretical life of the LED device is 100,000 hours, which is far greater than the working life of other components of the LED display. Therefore, as long as the quality of the LED device is guaranteed, the operating current is appropriate, the PCB heat dissipation design is reasonable, and the display production process is rigorous, LED devices will be one of the most durable parts of the display screen.

    LED devices can determine the quality of the LED display. China is a big producer of LED devices and a gathering place for LED display screens. LED display high-tech requirements are the future development trend, LED display high-quality requirements, not only about the direction of LED display manufacturers, but also implicated the development of LED display device manufacturers.

       



6.Attenuation characteristics

After the LED display is working for a long time, there will be a phenomenon that the brightness is decreased and the display color is inconsistent, which is mainly caused by the brightness attenuation of the LED device. Attenuation of the LED brightness will cause the display screen to have reduced brightness. The inconsistency of the brightness attenuation of red, green, and blue LEDs can cause inconsistencies in the color of the LED display. High-quality LED devices can well control the brightness attenuation. According to 1000 hours normal temperature light 20mA standard, red attenuation should be less than 2%, blue, green attenuation should be less than 10%, so blue, green LED display screen design do not try to use 20mA current, preferably only 70% to 80 % of rated current.

    In addition to the attenuation characteristics of red, green, and blue LEDs, the usage of current, PCB board heat dissipation design, and the work temperature of the LED display all affect attenuation.




7.Size

The size of the LED device affects the pixel distance of the LED display, ie the resolution. The 5mm elliptical lamp is mainly used for outdoor display of P16 and above. The 3mm elliptical lamp is mainly used for outdoor display of P12.5, P12, P10. The 2020 type of patch LED is mainly used for indoor display of P2, P3, etc. Under the premise of constant pixel pitch, the LED device increases in size, which can increase the display area and reduce the sense of particle. However, since the area of the black area is reduced, the contrast is reduced; on the contrary, the LED size is reduced, the display area is reduced, and the sense of particle is increased. The area of the black area increases, increasing the contrast.

8. Consistency

The LED display is composed of numerous pixels composed of red, green and blue LEDs. The consistency of the brightness and wavelength of each LED determines the brightness uniformity, white balance consistency and color consistency of the entire display.In general, display manufacturers require device supplier to provide LEDs with wavelength range of 5nm and brightness range of 1:1.3. These specifications can be graded achieved by device supplier using a spectrophotometric separator. Voltage consistency is generally not required.

   

The consistency of the angle 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 consistent matching of brightness changes of red, green, and blue LEDs at different angles, it is necessary to make science design the encapsulation lens design and raw material selection, which is depending on the encapsulation supplier’s technical level. Even if  normal direction white balance of the screen better , if LED angle consistency is not good, the whole screen different angles of the white balance effect will be bad. The LED lamp angle consistency characteristics can be measured with an LED angle comprehensive tester, which is particularly important for medium and high-end displays.


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