Eight major influences of led beads on led display

- Jul 16, 2019-

Many customers understand that led lamp bead (also called led chip) is a very important core device of led display screen, which plays a crucial role in the performance. However, most people only know this concept, so what impact does led lamp bead have on led display screen? There are not many that can be clearly distinguished, so here is a detailed introduction to the eight major impacts of led beads on led display screen.


Eight major influences of led beads on led display screens


Perspective effect


The Angle of view of the LED display depends on the Angle of view of the LED bead. At present, most outdoor display screens use a horizontal viewing Angle of 100°. , vertical Angle of view 50°; Elliptic LED and indoor display screen are both 120° horizontally and vertically. The patch LED. Due to its particularity, the display screen on the expressway is generally selected at 30°; A circular LED with a view Angle is enough. Some tall buildings require more vertical viewing. Angle of view and brightness are mutually contradictory, large Angle of view will inevitably reduce brightness. The choice of perspective depends on the specific purpose.


Brightness influence


LED brightness is an important determinant of display brightness. The higher the LED brightness, the larger the allowance of using current, which is good for saving power consumption and keeping the LED stable. Leds have different Angle values. When the chip brightness is set, the smaller the Angle, the brighter the LED, but the smaller the viewing Angle of the display. Generally, 100 degree LED should be selected to ensure sufficient viewing Angle of the display screen. For screens with different distances and different line-of-sight, there should be a balance between brightness, Angle and price.


Failure rate comparison


Since the full-color display screen is composed of tens of thousands or even hundreds of thousands of pixels composed of red, green and blue leds, the failure of any color LED will affect the overall visual effect of the display screen. Generally speaking, according to the industry experience, the failure rate should not be more than 3/10000 before the LED display starts to be assembled and aging 72 hours before shipment (refers to the failure caused by the LED lamp bead itself).


Antistatic capacity


LED is a semiconductor device, which is sensitive to static electricity and easy to cause static electricity failure. Therefore, the anti-static ability is very important for the life of the display screen. Generally speaking, the failure voltage of LED body electrostatic mode test should not be lower than 2000V.


Led beads have a direct impact on led display life


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


LED devices account for 70% of the price of LED display, so LED devices can determine the quality of LED display. China is the leading manufacturer of LED devices and the gathering place of LED display screens. The high technical requirements of LED display are the future development trend. The high quality requirements of LED display are not only related to the trend of LED display manufacturers, but also related to the development of LED display device manufacturers. From LED devices to promote the transformation of China from a leading manufacturer of LED display screens to a leading manufacturer of LED displays.


Attenuation characteristic


LED display screen after a long time to work will appear brightness decline and display color inconsistent phenomenon, mainly due to LED device brightness attenuation. The attenuation of LED brightness will reduce the brightness of the whole display screen. The inconsistency of red, green and blue LED brightness attenuation amplitude will cause the inconsistency of LED display color, which is the phenomenon that we often say the display spends. High quality LED devices can control the brightness attenuation. According to the standard of lighting 20mA at room temperature for 1000 hours, the red attenuation should be less than 2%, and the blue and green attenuation should be less than 10%. Therefore, the blue and green LED should not use 20mA current when designing the display screen, and it is best to use only 70% to 80% of the rated current.


In addition to the red, green and blue LED characteristics, attenuation characteristics are affected by the use of current, PCB heat dissipation design, and display environment temperature.


size


The size of LED devices affects the pixel distance of LED display, namely the resolution. 5mm oval lamp is mainly used for outdoor display screen above P16, 3mm oval lamp is mainly used for outdoor display screen of P12.5, P12 and P10, type 3528 patch LED is mainly used for indoor display screen of P6 and P8, type 2020 patch LED is mainly used for indoor display screen of P2 and P3, etc. Under the premise of constant point spacing, the size of LED devices increases, which can increase the display area and reduce the graininess. However, due to the decrease of the black area, the contrast will be reduced. On the contrary, LED size decreases, reducing display area, increasing graininess, increasing black area and increasing contrast.


Full screen consistency


The full-color display screen is composed of numerous red, green and blue LED pixels, and the brightness and wavelength consistency of each color LED determines the brightness consistency, white balance consistency and chroma consistency of the entire display screen. Generally speaking, display manufacturers require device suppliers to provide 5nm wavelength range and 1:1.3 brightness range of leds, which can be graded by device suppliers through spectral separators. Voltage consistency is generally not required.


Due to the Angle of LED, so the full color LED display screen also has the direction of visual Angle, the direct performance is at different angles of view, its brightness will increase or decrease. In this way, the Angle consistency of red, green and blue LED lamp beads will seriously affect the consistency of white balance at different angles, and directly affect the fidelity of LED display screen video color.


In order to achieve the matching consistency of red, green and blue led brightness changes at different angles, led display manufacturers need to carry out strict scientific design in packaging lens design and raw material selection, which depends on the technical level of packaging suppliers. If the Angle consistency of LED is not good, the white balance effect of the whole screen at different angles will be bad. The Angle consistency characteristic of LED lamp bead can be measured by LED Angle comprehensive tester, which is particularly important for the high-end LED display screen.