1, perspective
Led display depends on the perspective of LED lamp beads perspective. At present, most of the outdoor display screen selection angle of 100 °, vertical viewing angle of 50 °; oval LED, indoor display is selected vertical and vertical are 120 °; patch LED. Expressway on the display because of its special nature of the general selection of 30 °; angle of the circular LED is enough. Some high-rise display on the vertical viewing angle requirements are higher. Perspective and brightness are contradictory, a large perspective will inevitably reduce the brightness. The choice of perspective needs to be determined according to the specific purpose.
2, brightness
LED brightness is an important determinant of the brightness of the display. LED brightness is higher, the greater the use of current margin, to save power, to maintain stability of the LED is good. LED has a different angle value, the chip brightness has been set in the case, the smaller the angle, LED is brighter, but the smaller the viewing angle of the display. Generally should choose 100 degrees of LED to ensure that the display screen enough angle. For a different point spacing and different line of sight of the display, should be in brightness, angle and price to find a balance point.
3, failure rate
As the full color display by the tens of thousands or even hundreds of thousands of groups of red, green and blue LED composed of three pixels, any color LED failure will affect the overall visual effects of the display. In general, according to industry experience, in the led display began to assembly 72 hours before the failure of the failure rate should not be higher than three ten thousandths (referring to the LED lamp itself caused by the failure).
4, anti-static ability
LED is a semiconductor device, sensitive to static electricity, easily lead to electrostatic failure, so the anti-static capacity of the display life is essential. In general, LED body electrostatic mode test failure voltage should not be less than 2000V.
5, life expectancy
LED device theoretical life of 100,000 hours, much larger than the other parts of the LED display service life, so as long as the LED device quality assurance, working current, PCB cooling design is reasonable, the display production process rigorous, LED devices will be the entire screen One of the most durable parts of the machine.
LED devices accounted for 70% of the proportion of the price of the display screen, so that LED devices can determine the quality of the advantages of led display. China is the production of LED devices power, but also led display system to do the gathering. led display of high-tech requirements is the future development trend, led display of high-quality requirements, not only on the direction of led display manufacturers, but also implicated in the development of LED display device manufacturers. From the LED device gatekeeper, to promote China by the led display manufacturing power to the production of power led display changes.
6, attenuation characteristics
Led display after a long period of time will appear after the decline in brightness and display color inconsistencies, mainly due to the brightness of LED devices caused by attenuation. LED brightness attenuation will cause the display screen brightness reduction. Red, green, blue LED brightness attenuation of the inconsistency will lead to LED display color inconsistencies, that is, we often said that the display took the phenomenon. High-quality LED devices can be very good control of brightness attenuation. According to 1000 hours at room temperature lit 20mA standard, red attenuation should be less than 2%, blue, green attenuation should be less than 10%, so blue, green LED design in the display as far as possible not to use 20mA current, preferably only 70% to 80 % Of the rated current.
In addition to the characteristics of red, green and blue LED itself, the use of current, PCB board thermal design, display the use of ambient temperature, etc. are affected by attenuation.
7, size
LED device size led display pixel pixel distance, that is, resolution. 5mm oval lamp is mainly used for P16 outdoor display, 3mm oval lamp is mainly used for P12.5, P12, P10 outdoor display, 3528 SMD LED is mainly used for P6, P8 indoor display, 2020 SMD LED is mainly used for P2, P3 and other indoor display. In the premise of the same pitch, LED device size increases, can increase the display area, reduce the grainy, but because the black area decreased, will reduce the contrast; the contrary, LED size decreases, reducing the display area, grain increased , Black area increased, increasing the contrast.
8, consistency
Full color display is composed of countless red, green, blue LED composed of pixels, each color LED brightness, wavelength consistency determines the brightness of the entire display consistency, white balance consistency, consistent color Sex. In general, the display manufacturer requires the device supplier to provide 5nm wavelength range and 1: 1.3 brightness range of the LED, these indicators can be device suppliers through the classification of color separation machine to achieve. The consistency of the voltage is generally not required.
As the LED is angular, so full-color LED display also has the angle of direction, that is, in different angles, the brightness is increasing or decreasing. In this way, the consistency of the red, green and blue colors of the LED will seriously affect the consistency of the white balance at different angles, directly affecting the fidelity of the video color of the display. To achieve red, green and blue LED at different angles when the brightness of the matching consistency, the need for packaging lens design, raw material selection on the rigorous scientific design, depending on the packaging supplier's technical level. Normal direction white balance no matter how good the display, if the LED angle consistency is not good, the whole screen different angles of the white balance effect will be bad. LED lamp beads angle consistency characteristics can be measured using LED angle tester, for high-end display is particularly important.